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7184 KiB

Open AccessArticle

Bactericidal Effect of Lauric Acid-Loaded PCL-PEG-PCL Nano-Sized Micelles on Skin Commensal Propionibacterium acnes

by Thi-Quynh-Mai Tran, Ming-Fa Hsieh, Keng-Lun Chang, Quoc-Hue Pho, Van-Cuong Nguyen, Ching-Yi Cheng and Chun-Ming Huang

Polymers 2016, 8(9), 321; https://doi.org/10.3390/polym8090321 - 27 Aug 2016

Cited by 28 | Viewed by 13476

Abstract

Acne is the over growth of the commensal bacteria Propionibacterium acnes (P. acnes) on human skin. Lauric acid (LA) has been investigated as an effective candidate to suppress the activity of P. acnes. Although LA is nearly insoluble in water, [...] Read more.

Acne is the over growth of the commensal bacteria Propionibacterium acnes (P. acnes) on human skin. Lauric acid (LA) has been investigated as an effective candidate to suppress the activity of P. acnes. Although LA is nearly insoluble in water, dimethyl sulfoxide (DMSO) has been reported to effectively solubilize LA. However, the toxicity of DMSO can limit the use of LA on the skin. In this study, LA-loaded poly(ɛ-caprolactone)-poly(ethylene glycol)-poly(ɛ-caprolactone) micelles (PCL-PEG-PCL) were developed to improve the bactericidal effect of free LA on P. acnes. The block copolymers mPEG-PCL and PCL-PEG-PCL with different molecular weights were synthesized and characterized using ¹H Nuclear Magnetic Resonance spectroscopy (¹H NMR), Fourier-transform infrared spectroscopy (FT-IR), Gel Permeation Chromatography (GPC), and Differential Scanning Calorimetry (DSC). In the presence of LA, mPEG-PCL diblock copolymers did not self-assemble into nano-sized micelles. On the contrary, the average particle sizes of the PCL-PEG-PCL micelles ranged from 50–198 nm for blank micelles and 27–89 nm for LA-loaded micelles. The drug loading content increased as the molecular weight of PCL-PEG-PCL polymer increased. Additionally, the minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC) of free LA were 20 and 80 μg/mL, respectively. The MICs and MBCs of the micelles decreased to 10 and 40 μg/mL, respectively. This study demonstrated that the LA-loaded micelles are a potential treatment for acne. Full article

(This article belongs to the Special Issue Functional Polymers for Medical Applications)

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3392 KiB

Open AccessArticle

An Osteoconductive Antibiotic Bone Eluting Putty with a Custom Polymer Matrix

by John Curley, Mohammad Raquibul Hasan, Jacob Larson, Benjamin D. Brooks, Qianhui Liu, Tanmay Jain, Abraham Joy and Amanda E. Brooks

Polymers 2016, 8(7), 247; https://doi.org/10.3390/polym8070247 - 30 Jun 2016

Cited by 4 | Viewed by 6919

Abstract

With the rising tide of antibiotic resistant bacteria, extending the longevity of the current antibiotic arsenal is becoming a necessity. Developing local, controlled release antibiotic strategies, particularly for difficult to penetrate tissues such as bone, may prove to be a better alternative. Previous [...] Read more.

With the rising tide of antibiotic resistant bacteria, extending the longevity of the current antibiotic arsenal is becoming a necessity. Developing local, controlled release antibiotic strategies, particularly for difficult to penetrate tissues such as bone, may prove to be a better alternative. Previous efforts to develop an osteoconductive local antibiotic release device for bone were created as solid molded composites; however, intimate contact with host bone was found to be critical to support host bone regrowth; thus, an osteocondconductive antibiotic releasing bone void filling putty was developed. Furthermore, a controlled releasing polymer matrix was refined using pendant-functionalized diols to provide tailorable pharmacokinetics. In vitro pharmacokinetic and bioactivity profiles were compared for a putty formulation with an analogous composition as its molded counterpart as well as four new pendant-functionalized polymers. A best-fit analysis of polymer composition in either small cylindrical disks or larger spheres revealed that the new pendant-functionalized polymers appear to release vancomycin via both diffusion and erosion regardless of the geometry of the putty. In silico simulations, a valuable technique for diffusion mediated controlled release models, will be used to confirm and optimize this property. Full article

(This article belongs to the Special Issue Functional Polymers for Medical Applications)

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3711 KiB

Open AccessArticle

Production and Characterization of a Novel, Electrospun, Tri-Layer Polycaprolactone Membrane for the Segregated Co-Culture of Bone and Soft Tissue

by Sasima Puwanun, Frazer J. Bye, Moira M. Ireland, Sheila MacNeil, Gwendolen C. Reilly and Nicola H. Green

Polymers 2016, 8(6), 221; https://doi.org/10.3390/polym8060221 - 07 Jun 2016

Cited by 6 | Viewed by 5493

Abstract

Composite tissue-engineered constructs combining bone and soft tissue have applications in regenerative medicine, particularly dentistry. This study generated a tri-layer, electrospun, poly-ε-caprolactone membrane, with two microfiber layers separated by a layer of nanofibers, for the spatially segregated culture of mesenchymal progenitor cells (MPCs) [...] Read more.

Composite tissue-engineered constructs combining bone and soft tissue have applications in regenerative medicine, particularly dentistry. This study generated a tri-layer, electrospun, poly-ε-caprolactone membrane, with two microfiber layers separated by a layer of nanofibers, for the spatially segregated culture of mesenchymal progenitor cells (MPCs) and fibroblasts. The two cell types were seeded on either side, and cell proliferation and spatial organization were investigated over several weeks. Calcium deposition by MPCs was detected using xylenol orange (XO) and the separation between fibroblasts and the calcified matrix was visualized by confocal laser scanning microscopy. SEM confirmed that the scaffold consisted of two layers of micron-diameter fibers with a thin layer of nano-diameter fibers in-between. Complete separation of cell types was maintained and calcified matrix was observed on only one side of the membrane. This novel tri-layer membrane is capable of supporting the formation of a bilayer of calcified and non-calcified connective tissue. Full article

(This article belongs to the Special Issue Functional Polymers for Medical Applications)

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3051 KiB

Open AccessArticle

Molecularly Imprinted Polymers for the Identification and Separation of Chiral Drugs and Biomolecules

by Sha Yang, Yonghui Wang, Yingda Jiang, Shuang Li and Wei Liu

Polymers 2016, 8(6), 216; https://doi.org/10.3390/polym8060216 - 03 Jun 2016

Cited by 78 | Viewed by 10701

Abstract

Molecularly imprinting polymers (MIPs) have been extensively applied in chromatography for the separation of chiral drugs. In this review, we mainly summarize recent developments of various MIPs used as chiral stationary phases (CSPs) in high performance liquid chromatography (HPLC), capillary electrochromatography (CEC), and [...] Read more.

Molecularly imprinting polymers (MIPs) have been extensively applied in chromatography for the separation of chiral drugs. In this review, we mainly summarize recent developments of various MIPs used as chiral stationary phases (CSPs) in high performance liquid chromatography (HPLC), capillary electrochromatography (CEC), and supercritical fluid chromatography (SFC). Among them, HPLC has the advantages of straightforward operation and high selectivity. However, the low separation efficiency, due to slow interaction kinetics and heavy peak broadening, is the main challenge for the application of MIPs in HPLC. On the other hand, CEC possesses both the high selectivity of HPLC and the high efficiency of capillary electrophoresis. In CEC, electroosmotic flow is formed across the entire column and reduces the heavy peak broadening observed in HPLC mode. SFC can modify the low interaction kinetics in HPLC when supercritical fluids are utilized as mobile phases. If SFC and MIP-based CSPs can be well combined, better separation performance can be achieved. Particles, monoliths and membrane are typical formats of MIPs. Traditional MIP particles produced by bulk polymerization have been replaced by MIP particles by surface imprinting technology, which are highly consistent in size and shape. Monolithic MIPs are prepared by in situ method in a column, greatly shortening the pre-preparation time. Some novel materials, such as magnetic nanoparticles, are integrated into the MIPs to enhance the controllability and efficiency of the polymerization. This review will be helpful to guide the preparation, development, and application of MIPs in chromatographic and electrophoretic enantioseparation. Full article

(This article belongs to the Special Issue Functional Polymers for Medical Applications)

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4153 KiB

Open AccessFeature PaperArticle

Engineering Porous Poly(lactic acid) Scaffolds with High Mechanical Performance via a Solid State Extrusion/Porogen Leaching Approach

by Hua-Mo Yin, Jing Qian, Jin Zhang, Zai-Fu Lin, Jian-Shu Li, Jia-Zhuang Xu and Zhong-Ming Li

Polymers 2016, 8(6), 213; https://doi.org/10.3390/polym8060213 - 31 May 2016

Cited by 54 | Viewed by 12358

Abstract

A knotty issue concerning the poor mechanical properties exists in the porogen leaching approach to porous scaffolds, despite its advantage in tuning pore structure. To address this hurdle, solid state extrusion (SSE) combined with porogen leaching was utilized to engineer porous scaffolds of [...] Read more.

A knotty issue concerning the poor mechanical properties exists in the porogen leaching approach to porous scaffolds, despite its advantage in tuning pore structure. To address this hurdle, solid state extrusion (SSE) combined with porogen leaching was utilized to engineer porous scaffolds of poly(lactic acid) (PLA). Advances introduced by poly(ethylene glycol) (PEG) caused the PLA ductile to be processed and, on the other hand, enabled the formation of interconnected pores. Thus, a well-interconnected porous architecture with high connectivity exceeding 97% and elevated porosity over 60% was obtained in the as-prepared PLA scaffolds with the composition of NaCl higher than 75.00 wt % and PEG beyond 1.25 wt %. More strikingly, the pore walls of macropores encompassed countless micropores and rough surface topography, in favor of transporting nutrients and metabolites as well as cell attachment. The prominent compressive modulus of the PLA scaffolds was in the range of 85.7–207.4 MPa, matching the normal modulus of human trabecular bone (50–250 MPa). By means of alkaline modification to improve hydrophilicity, biocompatible porous PLA scaffolds exhibited good cell attachment. These results suggest that the SSE/porogen leaching approach provides an eligible clue for fabricating porous scaffolds with high mechanical performance for use as artificial extracellular matrices. Full article

(This article belongs to the Special Issue Functional Polymers for Medical Applications)

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6657 KiB

Open AccessArticle

Synthesis of New Polyether Ether Ketone Derivatives with Silver Binding Site and Coordination Compounds of Their Monomers with Different Silver Salts

by Jérôme Girard, Nathalie Joset, Aurélien Crochet, Milène Tan, Anja Holzheu, Priscilla S. Brunetto and Katharina M. Fromm

Polymers 2016, 8(6), 208; https://doi.org/10.3390/polym8060208 - 30 May 2016

Cited by 5 | Viewed by 8831

Abstract

Polyether ether ketone (PEEK) is a well-known polymer used for implants and devices, especially spinal ones. To overcome the biomaterial related infection risks, 4-4′-difluorobenzophenone, the famous PEEK monomer, was modified in order to introduce binding sites for silver ions, which are [...] Read more.

Polyether ether ketone (PEEK) is a well-known polymer used for implants and devices, especially spinal ones. To overcome the biomaterial related infection risks, 4-4′-difluorobenzophenone, the famous PEEK monomer, was modified in order to introduce binding sites for silver ions, which are well known for their antimicrobial activity. The complexation of these new monomers with different silver salts was studied. Crystal structures of different intermediates were obtained with a linear coordination between two pyridine groups and the silver ions in all cases. The mechanical and thermal properties of different new polymers were characterized. The synthesized PEEKN5 polymers showed similar properties than the PEEK ones whereas the PEEKN7 polymers showed similar thermal properties but the mechanical properties are not as good as the ones of PEEK. To improve these properties, these polymers were complexed with silver nitrate in order to “cross-link” with silver ions. The presence of ionic silver in the polymer was then confirmed by thermogravimetric analysis (TGA) and X-ray powder diffraction (XRPD). Finally, a silver-based antimicrobial compound was successfully coated on the surface of PEEKN5. Full article

(This article belongs to the Special Issue Functional Polymers for Medical Applications)

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6133 KiB

Open AccessArticle

Differentiation of Dental Pulp Stem Cells on Gutta-Percha Scaffolds

by Liudi Zhang, Yingjie Yu, Christopher Joubert, George Bruder, Ying Liu, Chung-Chueh Chang, Marcia Simon, Stephen G. Walker and Miriam Rafailovich

Polymers 2016, 8(5), 193; https://doi.org/10.3390/polym8050193 - 13 May 2016

Cited by 18 | Viewed by 6396

Abstract

Advances in treatment of tooth injury have shown that tooth regeneration from the pulp was a viable alternative of root canal therapy. In this study, we demonstrated that Gutta-percha, nanocomposites primarily used for obturation of the canal, are not cytotoxic and can induce [...] Read more.

Advances in treatment of tooth injury have shown that tooth regeneration from the pulp was a viable alternative of root canal therapy. In this study, we demonstrated that Gutta-percha, nanocomposites primarily used for obturation of the canal, are not cytotoxic and can induce differentiation of dental pulp stem cells (DPSC) in the absence of soluble mediators. Flat scaffolds were obtained by spin coating Si wafers with three Gutta-percha compounds: GuttaCore™, ProTaper™, and Lexicon™. The images of annealed surfaces showed that the nanoparticles were encapsulated, forming surfaces with root mean square (RMS) roughness of 136–211 nm. Then, by culturing DPSC on these substrates we found that after some initial difficulty in adhesion, confluent tissues were formed after 21 days. Imaging of the polyisoprene (PI) surfaces showed that biomineral deposition only occurred when dexamethasone was present in the media. Spectra obtained from the minerals was consistent with that of hydroxyapatite (HA). In contrast, HA deposition was observed on all Gutta-percha scaffolds regardless of the presence or absence of dexamethasone, implying that surface roughness may be an enabling factor in the differentiation process. These results indicate that Gutta-percha nanocomposites may be good candidates for pulp regeneration therapy. Full article

(This article belongs to the Special Issue Functional Polymers for Medical Applications)

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10895 KiB

Open AccessArticle

Polyurethane/Polylactide-Blend Films Doped with Zinc Ions for the Growth and Expansion of Human Olfactory Ensheathing Cells (OECs) and Adipose-Derived Mesenchymal Stromal Stem Cells (ASCs) for Regenerative Medicine Applications

by Krzysztof Marycz, Monika Marędziak, Jakub Grzesiak, Dariusz Szarek, Anna Lis and Jadwiga Laska

Polymers 2016, 8(5), 175; https://doi.org/10.3390/polym8050175 - 30 Apr 2016

Cited by 11 | Viewed by 7788

Abstract

Polymeric biomaterials based on polyurethane and polylactide blends are promising candidates for regenerative medicine applications as biocompatible, bioresorbable carriers. In current research we showed that 80/20 polyurethane/polylactide blends (PU/PLDL) with confirmed biological properties in vitro may be further improved by the addition of [...] Read more.

Polymeric biomaterials based on polyurethane and polylactide blends are promising candidates for regenerative medicine applications as biocompatible, bioresorbable carriers. In current research we showed that 80/20 polyurethane/polylactide blends (PU/PLDL) with confirmed biological properties in vitro may be further improved by the addition of ZnO nanoparticles for the delivery of bioactive zinc oxide for cells. The PU/PLDL blends were doped with different concentrations of ZnO (0.001%, 0.01%, 0.05%) and undertaken for in vitro biological evaluation using human adipose stromal stem cells (ASCs) and olfactory ensheathing cells (OECs). The addition of 0.001% of ZnO to the biomaterials positively influenced the morphology, proliferation, and phenotype of cells cultured on the scaffolds. Moreover, the analysis of oxidative stress markers revealed that 0.001% of ZnO added to the material decreased the stress level in both cell lines. In addition, the levels of neural-specific genes were upregulated in OECs when cultured on sample 0.001 ZnO, while the apoptosis-related genes were downregulated in OECs and ASCs in the same group. Therefore, we showed that PU/PLDL blends doped with 0.001% of ZnO exert beneficial influence on ASCs and OECs in vitro and they may be considered for future applications in the field of regenerative medicine. Full article

(This article belongs to the Special Issue Functional Polymers for Medical Applications)

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5270 KiB

Open AccessArticle

Stereocomplex-Reinforced PEGylated Polylactide Micelle for Optimized Drug Delivery

by Chunsheng Feng, Meihua Piao and Di Li

Polymers 2016, 8(4), 165; https://doi.org/10.3390/polym8040165 - 22 Apr 2016

Cited by 18 | Viewed by 6402

Abstract

The instability of PEGylated polylactide micelles is a challenge for drug delivery. Stereocomplex interaction between racemic polylactide chains with different configurations provides an effective strategy to enhance the stability of micelles as the nanocarriers of drugs. In this work, a stereocomplex micelle (SCM) [...] Read more.

The instability of PEGylated polylactide micelles is a challenge for drug delivery. Stereocomplex interaction between racemic polylactide chains with different configurations provides an effective strategy to enhance the stability of micelles as the nanocarriers of drugs. In this work, a stereocomplex micelle (SCM) self-assembled from the amphiphilic triblock copolymers comprising poly(ethylene glycol) (PEG), and dextrorotatory and levorotatory polylactides (PDLA and PLLA) was applied for efficient drug delivery. The spherical SCM showed the smallest scale and the lowest critical micelle concentration (CMC) than the micelles with single components attributed to the stereocomplex interaction between PDLA and PLLA. 10-Hydroxycamptothecin (HCPT) as a model antitumor drug was loaded into micelles. Compared with the loading micelles from individual PDLA and PLLA, the HCPT-loaded SCM exhibited the highest drug loading efficiency (DLE) and the slowest drug release in phosphate-buffered saline (PBS) at pH 7.4, indicating its enhanced stability in circulation. More fascinatingly, the laden SCM was demonstrated to have the highest cellular uptake of HCPT and suppress malignant cells most effectively in comparison to the HCPT-loaded micelles from single copolymer. In summary, the stereocomplex-enhanced PLA–PEG–PLA micelle may be promising for optimized drug delivery in the clinic. Full article

(This article belongs to the Special Issue Functional Polymers for Medical Applications)

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10111 KiB

Open AccessFeature PaperArticle

The in Vitro and in Vivo Degradation of Cross-Linked Poly(trimethylene carbonate)-Based Networks

by Liqun Yang, Jianxin Li, Miao Li and Zhongwei Gu

Polymers 2016, 8(4), 151; https://doi.org/10.3390/polym8040151 - 19 Apr 2016

Cited by 30 | Viewed by 7651

Abstract

The degradation of the poly(trimethylene carbonate) (PTMC) and poly(trimethylene carbonate-co-ε-caprolactone) (P(TMC-co-CL)) networks cross-linked by 0.01 and 0.02 mol % 2,2′-bis(trimethylene carbonate-5-yl)-butylether (BTB) was carried out in the conditions of hydrolysis and enzymes in vitro and subcutaneous implantation in vivo [...] Read more.

The degradation of the poly(trimethylene carbonate) (PTMC) and poly(trimethylene carbonate-co-ε-caprolactone) (P(TMC-co-CL)) networks cross-linked by 0.01 and 0.02 mol % 2,2′-bis(trimethylene carbonate-5-yl)-butylether (BTB) was carried out in the conditions of hydrolysis and enzymes in vitro and subcutaneous implantation in vivo. The results showed that the cross-linked PTMC networks exhibited much faster degradation in enzymatic conditions in vitro and in vivo versus in a hydrolysis case due to the catalyst effect of enzymes; the weight loss and physical properties of the degraded networks were dependent on the BTB amount. The morphology observation in lipase and in vivo illustrated that enzymes played an important role in the surface erosion of cross-linked PTMC. The hydrolytic degradation rate of the cross-linked P(TMC-co-CL) networks increased with increasing ε-caprolactone (CL) content in composition due to the preferential cleavage of ester bonds. Cross-linking is an effective strategy to lower the degradation rate and enhance the form-stability of PTMC-based materials. Full article

(This article belongs to the Special Issue Functional Polymers for Medical Applications)

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3322 KiB

Open AccessArticle

pH-Triggered Sheddable Shielding System for Polycationic Gene Carriers

by Jialiang Xia, Huayu Tian, Jie Chen, Lin Lin, Zhaopei Guo, Bing Han, Hongyan Yang and Zongcai Feng

Polymers 2016, 8(4), 141; https://doi.org/10.3390/polym8040141 - 14 Apr 2016

Cited by 4 | Viewed by 5358

Abstract

For improving the therapeutic efficiency of tumors and decreasing undesirable side effects, ternary complexes were developed by coating pH-sensitive PEG-b-PLL-g-succinylsulfathiazole (hereafter abbreviated as PPSD) with DNA/PEI polyplexes via electrostatic interaction. PPSD can efficiently shield the surface charge of DNA/PEI. [...] Read more.

For improving the therapeutic efficiency of tumors and decreasing undesirable side effects, ternary complexes were developed by coating pH-sensitive PEG-b-PLL-g-succinylsulfathiazole (hereafter abbreviated as PPSD) with DNA/PEI polyplexes via electrostatic interaction. PPSD can efficiently shield the surface charge of DNA/PEI. The gene transfection efficiency of ternary complexes was lower than that of DNA/PEI at pH 7.4; however, it recovered to the same level as that of DNA/PEI at pH 6.0, attributed to the pH-triggered release of DNA/PEI from ternary complexes. Cell uptake results also exhibited the same trend as transfection at different pH values. The suitable ability for pH-triggered shielding/deshielding estimated that PPSD demonstrates potential as a shielding system for use in in vivo gene delivery. Full article

(This article belongs to the Special Issue Functional Polymers for Medical Applications)

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12033 KiB

Open AccessArticle

Structural Properties and Antifungal Activity against Candida albicans Biofilm of Different Composite Layers Based on Ag/Zn Doped Hydroxyapatite-Polydimethylsiloxanes

by Andreea Groza, Carmen Steluta Ciobanu, Cristina Liana Popa, Simona Liliana Iconaru, Patrick Chapon, Catalin Luculescu, Mihai Ganciu and Daniela Predoi

Polymers 2016, 8(4), 131; https://doi.org/10.3390/polym8040131 - 09 Apr 2016

Cited by 44 | Viewed by 10212

Abstract

Modern medicine is still struggling to find new and more effective methods for fighting off viruses, bacteria and fungi. Among the most dangerous and at times life-threatening fungi is Candida albicans. Our work is focused on surface and structural characterization of hydroxyapatite, [...] Read more.

Modern medicine is still struggling to find new and more effective methods for fighting off viruses, bacteria and fungi. Among the most dangerous and at times life-threatening fungi is Candida albicans. Our work is focused on surface and structural characterization of hydroxyapatite, silver doped hydroxyapatite and zinc doped hydroxyapatite deposited on a titanium substrate previously coated with polydimethylsiloxane (HAp-PDMS, Ag:HAp-PDMS, Zn:HAp-PDMS) by different techniques: Scanning Electron Microscopy (SEM), Glow Discharge Optical Emission Spectroscopy (GDOES) and Fourier Transform Infrared Spectroscopy (FTIR). The morphological studies revealed that the use of the PDMS polymer as an interlayer improves the quality of the coatings. The structural characterizations of the thin films revealed the basic constituents of both apatitic and PDMS structure. In addition, the GD depth profiles indicated the formation of a composite material as well as the successful embedding of the HAp, Zn:HAp and Ag:HAp into the polymer. On the other hand, in vitro evaluation of the antifungal properties of Ag:HAp-PDMS and Zn:HAp-PDMS demonstrated the fungicidal effects of Ag:HAp-PDMS and the potential antifungal effect of Zn:HAp-PDMS composite layers against C. albicans biofilm. The results acquired in this research complete previous research on the potential use of new complex materials produced by nanotechnology in biomedicine. Full article

(This article belongs to the Special Issue Functional Polymers for Medical Applications)

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7320 KiB

Open AccessArticle

A Thixotropic Polyglycerol Sebacate-Based Supramolecular Hydrogel as an Injectable Drug Delivery Matrix

by Hongye Ye, Cally Owh, Shan Jiang, Cavin Zhen Quan Ng, Daniel Wirawan and Xian Jun Loh

Polymers 2016, 8(4), 130; https://doi.org/10.3390/polym8040130 - 07 Apr 2016

Cited by 47 | Viewed by 8738

Abstract

We have developed a “self-healing” polyglycerol sebacate—polyethylene glycol methyl ether methacrylate (PGS-PEGMEMA)/α-Cyclodextrin (αCD) hydrogel which could be sheared into a liquid during injection and has the potential to quickly “heal” itself back into gel post-injection. This hydrogel was shown to be biocompatible and [...] Read more.

We have developed a “self-healing” polyglycerol sebacate—polyethylene glycol methyl ether methacrylate (PGS-PEGMEMA)/α-Cyclodextrin (αCD) hydrogel which could be sheared into a liquid during injection and has the potential to quickly “heal” itself back into gel post-injection. This hydrogel was shown to be biocompatible and biodegradable and therefore appropriate for use in vivo. Furthermore, the storage and loss moduli of the hydrogels could be tuned (by varying the concentration of αCD) between a fraction of a kPa to a few 100 kPa, a range that coincides with the moduli of cells and human soft tissues. This property would allow for this hydrogel to be used in vivo with maximal mechanical compatibility with human soft tissues. In vitro experiments showed that the hydrogel demonstrated a linear mass erosion profile and a biphasic drug (doxorubicin) release profile: Phase I was primarily driven by diffusion and Phase II was driven by hydrogel erosion. The diffusion mechanism was modeled with the First Order equation and the erosion mechanism with the Hopfenberg equation. This established fitting model could be used to predict releases with other drugs and estimate the composition of the hydrogel required to achieve a desired release rate. Full article

(This article belongs to the Special Issue Functional Polymers for Medical Applications)

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5088 KiB

Open AccessArticle

Fluorescent BAPAD Dendrimeric Antigens Are Efficiently Internalized by Human Dendritic Cells

by Pablo Mesa-Antunez, Daniel Collado, Yolanda Vida, Francisco Najera, Tahia Fernandez, Maria Jose Torres and Ezequiel Perez-Inestrosa

Polymers 2016, 8(4), 111; https://doi.org/10.3390/polym8040111 - 26 Mar 2016

Cited by 5 | Viewed by 5948

Abstract

A new fluorescent dendrimeric antigen (DeAn) based on a dendron with amoxicilloyl terminal groups was synthesized. The synthesis was carried out using a novel class of all-aliphatic polyamide dendrimer (BisAminoalkylPolyAmide Dendrimers, or BAPAD) involving the direct condensation of 3,3′-diazidopivalic acid as a building [...] Read more.

A new fluorescent dendrimeric antigen (DeAn) based on a dendron with amoxicilloyl terminal groups was synthesized. The synthesis was carried out using a novel class of all-aliphatic polyamide dendrimer (BisAminoalkylPolyAmide Dendrimers, or BAPAD) involving the direct condensation of 3,3′-diazidopivalic acid as a building block. Iterative azide reduction/amide formation increases the dendrimer generation. The BAPAD dendrimer was designed with a cystamine core. Reduction of the disulfide bond allows the incorporation of BAPAD dendrons into a 1,8-naphthalimide functionalized with a maleimide group. The fluorescence properties of DeAn were studied in PBS and compared with the properties of an equivalent dendron possessing amino-terminal groups. Both molecules shown high fluorescence quantum yields in PBS and could readily be visualized by fluorescence microscopy. DeAn was used as a synthetic antigen in a biomedical assay that tests their potential as an amoxicillin carrier in drug internalization by dendritic cells (DC) from tolerant and allergic patients. Cytometry data suggest that the dendrons are non-toxic and easily internalized by DCs, while confocal microscopy images indicate that the compounds are preferentially accumulated in the cytoplasm. These results indicate that BAPAD dendrons are good candidates for synthetic scaffolds for biomedical applications. Full article

(This article belongs to the Special Issue Functional Polymers for Medical Applications)

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Open AccessArticle

Interpenetration of Natural Polymer Aerogels by Supercritical Drying

by Lucia Baldino, Simona Concilio, Stefano Cardea and Ernesto Reverchon

Polymers 2016, 8(4), 106; https://doi.org/10.3390/polym8040106 - 24 Mar 2016

Cited by 70 | Viewed by 7659

Abstract

Natural polymers, such as alginate and gelatin, can be used to produce scaffolds for tissue engineering applications; but, their mechanical and biochemical performance should be improved. A possible solution to obtain this result, is the generation of multi-component scaffolds, by blending two or [...] Read more.

Natural polymers, such as alginate and gelatin, can be used to produce scaffolds for tissue engineering applications; but, their mechanical and biochemical performance should be improved. A possible solution to obtain this result, is the generation of multi-component scaffolds, by blending two or more polymers. One way to realize it, is the formation of an interpenetrating polymer network (IPN). In this work, the interpenetration of alginate and gelatin hydrogels has been successfully obtained and preserved by supercritical CO₂ (SC-CO₂) drying performed at 200 bar and 35 °C, using different blend compositions: from alginate/gelatin = 20:80 v/v to alginate/gelatin = 80:20 v/v. The process allowed modulation of morphology and mechanical properties of these blends. The overall result was made possible by the supercritical drying process that, working at zero surface tension, allows preserving the hydrogels nanostructure in the corresponding aerogels. Full article

(This article belongs to the Special Issue Functional Polymers for Medical Applications)

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1838 KiB

Open AccessFeature PaperArticle

l-Cystine-Crosslinked Polypeptide Nanogel as a Reduction-Responsive Excipient for Prostate Cancer Chemotherapy

by Liang He, Di Li, Zhongtang Wang, Weiguo Xu, Jixue Wang, Hui Guo, Chunxi Wang and Jianxun Ding

Polymers 2016, 8(2), 36; https://doi.org/10.3390/polym8020036 - 29 Jan 2016

Cited by 29 | Viewed by 7143

Abstract

Smart polymer nanogel-assisted drug delivery systems have attracted more and more attention in cancer chemotherapy because of their well-defined morphologies and pleiotropic functions in recent years. In this work, an l-cystine-crosslinked reduction-responsive polypeptide nanogel of methoxy poly(ethylene glycol)-poly(l-phenylalanine-co- [...] Read more.

Smart polymer nanogel-assisted drug delivery systems have attracted more and more attention in cancer chemotherapy because of their well-defined morphologies and pleiotropic functions in recent years. In this work, an l-cystine-crosslinked reduction-responsive polypeptide nanogel of methoxy poly(ethylene glycol)-poly(l-phenylalanine-co-l-cystine) (mPEG-P(LP-co-LC)) was employed as a smart excipient for RM-1 prostate cancer (PCa) chemotherapy. Doxorubicin (DOX), as a regular chemotherapy drug, was embedded in the nanogel. The loading nanogel marked as NG/DOX was shown to exhibit glutathione (GSH)-induced swelling and GSH-accelerated DOX release. Subsequently, NG/DOX showed efficient cellular uptake and proliferation inhibition. Furthermore, NG/DOX presented enhanced antitumor efficacy and security in an RM-1 PCa-grafted mouse model in vivo, indicating its great potential for clinical treatment. Full article

(This article belongs to the Special Issue Functional Polymers for Medical Applications)

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4075 KiB

Open AccessArticle

Reversible Self-Assembly of Backbone-Thermoresponsive Long Chain Hyperbranched Poly(N-Isopropyl Acrylamide)

by Ting-Ting Liu, Wei Tian, Yan-Li Song, Yang Bai, Peng-Li Wei, Hao Yao and Hong-Xia Yan

Polymers 2016, 8(2), 33; https://doi.org/10.3390/polym8020033 - 28 Jan 2016

Cited by 9 | Viewed by 5599

Abstract

In this paper, we mainly described the reversible self-assembly of a backbone-thermoresponsive, long-chain, hyperbranched poly(N-isopropyl acrylamide) (LCHBPNIPAM) in aqueous solution. Here, we revealed a reversible self-assembly behavior of LCHBPNIPAM aqueous solution derived from temperature. By controlling the temperature of LCHBPNIPAM aqueous [...] Read more.

In this paper, we mainly described the reversible self-assembly of a backbone-thermoresponsive, long-chain, hyperbranched poly(N-isopropyl acrylamide) (LCHBPNIPAM) in aqueous solution. Here, we revealed a reversible self-assembly behavior of LCHBPNIPAM aqueous solution derived from temperature. By controlling the temperature of LCHBPNIPAM aqueous solution, we tune the morphology of the LCHBPNIPAM self-assemblies. When the solution temperature increased from the room temperature to the lower critical solution temperature of PNIPAM segments, LCHBPNIPAM self-assembled from multi-compartment vesicles into solid micelles. The morphology of LCHBPNIPAM self-assemblies changed from solid micelles to multi-compartment vesicles again when the temperature decreased back to the room temperature. The size presented, at first, an increase, and then a decrease, tendency in the heating-cooling process. The above thermally-triggered self-assembly behavior of LCHBPNIPAM aqueous solution was investigated by dynamic/static light scattering, transmission electron microscopy, atomic force microscopy, fluorescence spectroscopy, ¹H nuclear magnetic resonance in D₂O, and attenuated total reflectance Fourier transform infrared spectroscopy. These results indicated that LCHBPNIPAM aqueous solution presents a reversible self-assembly process. The controlled release behaviors of doxorubicin from the vesicles and micelles formed by LCHBPNIPAM further proved the feasibility of these self-assemblies as the stimulus-responsive drug delivery system. Full article

(This article belongs to the Special Issue Functional Polymers for Medical Applications)

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9168 KiB

Open AccessArticle

Epirubicin-Complexed Polypeptide Micelle Effectively and Safely Treats Hepatocellular Carcinoma

by Qinglin Zhang, Jianxun Ding, Chenwei Lv, Weiguo Xu, Xun Sun and Xiangwei Meng

Polymers 2015, 7(11), 2410-2430; https://doi.org/10.3390/polym7111521 - 24 Nov 2015

Cited by 19 | Viewed by 9693

Abstract

Hepatocellular carcinoma (HCC) is the third leading cause of cancer-related mortality worldwide. Epirubicin (EPI) once acted as a main agent for HCC chemotherapy. However, the dosage-dependent side effects seriously limit its application in clinic. The purpose of this study is to develop an [...] Read more.

Hepatocellular carcinoma (HCC) is the third leading cause of cancer-related mortality worldwide. Epirubicin (EPI) once acted as a main agent for HCC chemotherapy. However, the dosage-dependent side effects seriously limit its application in clinic. The purpose of this study is to develop an effective nanocarrier to improve the efficacy and overcome the limitations of EPI. In this regard, the EPI-complexed micelle (i.e., mPEG-b-PGA/EPI) was prepared via the electrostatic interaction between the amino group in EPI and the carboxyl group in PGA segment of methoxy poly(ethylene glycol)-block-poly(l-glutamic acid) (mPEG-b-PGA), and the subsequent hydrophobic interaction among PGA/EPI complexes. The micelle appeared spherical with a diameter at around 90 nm and possessed a pH-sensitive release property of payload. The cytotoxicity and hemolysis assays in vitro, and the maximum tolerated dose tests in vivo confirmed that mPEG-b-PGA was a kind of safe material with excellent biocompatibility, while the drug-loaded micelle could obviously improve the tolerance of EPI. In addition, mPEG-b-PGA/EPI possessed significantly enhanced antitumor efficacy and security toward the H22-xenografted HCC murine model at macroscopic and microscopic levels compared with free EPI. All these results strongly indicate that mPEG-b-PGA/EPI may be a promising nanoplatform for EPI delivery in the chemotherapy of HCC. Full article

(This article belongs to the Special Issue Functional Polymers for Medical Applications)

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3608 KiB

Open AccessArticle

Amino Acid-Modified Polyethylenimines with Enhanced Gene Delivery Efficiency and Biocompatibility

by Qin-Fang Zhang, Chao-Ran Luan, Dong-Xiao Yin, Ji Zhang, Yan-Hong Liu, Qi Peng, Yong Xu and Xiao-Qi Yu

Polymers 2015, 7(11), 2316-2331; https://doi.org/10.3390/polym7111516 - 17 Nov 2015

Cited by 15 | Viewed by 7871

Abstract

The development of gene delivery vectors with high efficiency and biocompatibility is one of the key points of gene therapy. A series of polycations were prepared from polyethylenimine (PEI) with several amino acids or their analogs. The target polymers have different charge and [...] Read more.

The development of gene delivery vectors with high efficiency and biocompatibility is one of the key points of gene therapy. A series of polycations were prepared from polyethylenimine (PEI) with several amino acids or their analogs. The target polymers have different charge and hydrophilic/hydrophobic properties, which may affect their performance in the gene transfection process. Gel retardation and DLS assays showed that these polymers may condense DNA into nanoparticles with positive zeta potentials and proper sizes for cellular uptake. Luciferase reporter gene transfection results revealed their higher transfection efficiency than PEI; especially in the presence of serum, in which up to 23 times higher efficiency was achieved by employing glycolic acid-grafted PEI. Moreover, it was found that the degree of substitution on PEI has an apparent influence on the transfection, and the balance between electron-positive/negative groups largely affects the delivery process. The higher serum tolerance was also proven by BSA adsorption, flow cytometry and confocal microscopy assays. Results demonstrate that such type of polycations may serve as promising non-viral gene delivery vectors. Full article

(This article belongs to the Special Issue Functional Polymers for Medical Applications)

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3073 KiB

Open AccessArticle

Maleimide-Functionalized PEI600 Grafted Polyurethane: Synthesis, Nano-Complex Formation with DNA and Thiol-Conjugation of the Complexes for Dual DNA Transfection

by Wei-Chih Hung and Jong-Yuh Cherng

Polymers 2015, 7(10), 2131-2145; https://doi.org/10.3390/polym7101503 - 23 Oct 2015

Cited by 4 | Viewed by 7568

Abstract

A polyurethane (PU) grafted with small molecular weight polyethylenimine (PEI600) was synthesized. This PU-PEI600 can assemble DNA via electrostatic interactions into nano-sized polymer/DNA complexes. The complexes exhibited great transfection efficiency in delivering DNA along with a reduced cell toxicity comparing to commercial PEI25k [...] Read more.

A polyurethane (PU) grafted with small molecular weight polyethylenimine (PEI600) was synthesized. This PU-PEI600 can assemble DNA via electrostatic interactions into nano-sized polymer/DNA complexes. The complexes exhibited great transfection efficiency in delivering DNA along with a reduced cell toxicity comparing to commercial PEI25k (Mw ~25,000). In order to establish a system for concurrently delivering two different DNA or RNA molecules for cell reprogramming (e.g., induced pluripotent stem cells) or the necessity of multi-expression (e.g., double knock down), the PU-PEI600 was further functionalized with maleimide molecules. The novel PU-PEI600-maleimide would still effectively interact with assigned DNA and different functions of PU-PEI600-maleimide/DNA complexes were self-conjugated in presence of a dithiol molecule (1,6-hexanedithiol). In this study, two reporter genes (pEGFP-C2 and pLanRFP-N) were used and evidence of green/red fluorescence co-expression in cells was observed. This article brings a new concept and a practical method for a plurality of different DNA molecules that are more efficient to be concurrently delivered and co-expressed. This method is very helpful in studying cellular multi-regulation or in the treatment of disease with multiple gene defects in vivo. Full article

(This article belongs to the Special Issue Functional Polymers for Medical Applications)

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8113 KiB

Open AccessArticle

Comparative Efficacies of a 3D-Printed PCL/PLGA/β-TCP Membrane and a Titanium Membrane for Guided Bone Regeneration in Beagle Dogs

by Jin-Hyung Shim, Joo-Yun Won, Su-Jin Sung, Dong-Hyuk Lim, Won-Soo Yun, Young-Chan Jeon and Jung-Bo Huh

Polymers 2015, 7(10), 2061-2077; https://doi.org/10.3390/polym7101500 - 21 Oct 2015

Cited by 57 | Viewed by 11313

Abstract

This study was conducted to evaluate the effects of a 3D-printed resorbable polycaprolactone/poly(lactic-co-glycolic acid)/β-tricalcium phosphate (PCL/PLGA/β-TCP) membrane on bone regeneration and osseointegration in areas surrounding implants and to compare results with those of a non-resorbable titanium mesh membrane. After preparation of PCL/PLGA/β-TCP membranes [...] Read more.

This study was conducted to evaluate the effects of a 3D-printed resorbable polycaprolactone/poly(lactic-co-glycolic acid)/β-tricalcium phosphate (PCL/PLGA/β-TCP) membrane on bone regeneration and osseointegration in areas surrounding implants and to compare results with those of a non-resorbable titanium mesh membrane. After preparation of PCL/PLGA/β-TCP membranes using extrusion-based 3D printing technology; mechanical tensile testing and in vitro cell proliferation testing were performed. Implant surgery and guided bone regeneration were performed randomly in three groups (a no membrane group, a titanium membrane group, and a PCL/PLGA/β-TCP membrane group (n = 8 per group)). Histological and histometric analyses were conducted to evaluate effects on bone regeneration and osseointegration. Using the results of mechanical testing; a PCL/PLGA/β-TCP ratio of 2:6:2 was selected. The new bone areas (%) in buccal defects around implants were highest in the PCL/PLGA/β-TCP group and significantly higher than in the control group (p < 0.05). Bone-to-implant contact ratios (%) were also significantly higher in the PCL/PLGA/β-TCP and titanium groups than in the control group (p < 0.05). When the guided bone regeneration procedure was performed using the PCL/PLGA/β-TCP membrane; new bone formation around the implant and osseointegration were not inferior to those of the non-resorbable pre-formed titanium mesh membrane. Full article

(This article belongs to the Special Issue Functional Polymers for Medical Applications)

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1240 KiB

Open AccessArticle

Conjugation of ß-Adrenergic Antagonist Alprenolol to Implantable Polymer-Aescin Matrices for Local Delivery

by Ewa Oledzka, Dagmara Pachowska, Marcin Sobczak, Agnieszka Lis-Cieplak, Grzegorz Nalecz-Jawecki, Anna Zgadzaj and Waclaw Kolodziejski

Polymers 2015, 7(9), 1820-1836; https://doi.org/10.3390/polym7091484 - 18 Sep 2015

Cited by 5 | Viewed by 6801

Abstract

The sustained release of alprenolol, a ß-adrenergic antagonist, could be beneficial for the treatment of various heart diseases while reducing the side effects resulting from its continuous use. The novel and branched copolymers uniquely composed of biodegradable components (lactide and glycolide) have been [...] Read more.

The sustained release of alprenolol, a ß-adrenergic antagonist, could be beneficial for the treatment of various heart diseases while reducing the side effects resulting from its continuous use. The novel and branched copolymers uniquely composed of biodegradable components (lactide and glycolide) have been synthesized using natural and therapeutically-efficient ß-aescin-initiator, and consequently characterized to determine their structures and physicochemical properties. The obtained matrices were not cyto- and genotoxic towards bacterial luminescence, protozoan, and Salmonella typhimurium TA1535. The copolymers release the drug in vitro in a sustained manner and without burst release. The value of the drug released was strongly dependent on the copolymer composition and highly correlated with the hydrolytic matrices’ degradation results. Full article

(This article belongs to the Special Issue Functional Polymers for Medical Applications)

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Review

Jump to: Research

8660 KiB

Open AccessReview

Polyglycidol, Its Derivatives, and Polyglycidol-Containing Copolymers—Synthesis and Medical Applications

by Mateusz Gosecki, Mariusz Gadzinowski, Monika Gosecka, Teresa Basinska and Stanislaw Slomkowski

Polymers 2016, 8(6), 227; https://doi.org/10.3390/polym8060227 - 09 Jun 2016

Cited by 38 | Viewed by 13188

Abstract

Polyglycidol (or polyglycerol) is a biocompatible polymer with a main chain structure similar to that of poly(ethylene oxide) but with a –CH₂OH reactive side group in every structural unit. The hydroxyl groups in polyglycidol not only increase the hydrophilicity of this [...] Read more.

Polyglycidol (or polyglycerol) is a biocompatible polymer with a main chain structure similar to that of poly(ethylene oxide) but with a –CH₂OH reactive side group in every structural unit. The hydroxyl groups in polyglycidol not only increase the hydrophilicity of this polymer but also allow for its modification, leading to polymers with carboxyl, amine, and vinyl groups, as well as to polymers with bonded aliphatic chains, sugar moieties, and covalently immobilized bioactive compounds in particular proteins. The paper describes the current state of knowledge on the synthesis of polyglycidols with various topology (linear, branched, and star-like) and with various molar masses. We provide information on polyglycidol-rich surfaces with protein-repelling properties. We also describe methods for the synthesis of polyglycidol-containing copolymers and the preparation of nano- and microparticles that could be derived from these copolymers. The paper summarizes recent advances in the application of polyglycidol and polyglycidol-containing polymers as drug carriers, reagents for diagnostic systems, and elements of biosensors. Full article

(This article belongs to the Special Issue Functional Polymers for Medical Applications)

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1458 KiB

Open AccessReview

Polymers in Cartilage Defect Repair of the Knee: Current Status and Future Prospects

by Ralph M. Jeuken, Alex K. Roth, Ruud J. R. W. Peters, Corrinus C. Van Donkelaar, Jens C. Thies, Lodewijk W. Van Rhijn and Pieter J. Emans

Polymers 2016, 8(6), 219; https://doi.org/10.3390/polym8060219 - 04 Jun 2016

Cited by 68 | Viewed by 13263

Abstract

Cartilage defects in the knee are often seen in young and active patients. There is a need for effective joint preserving treatments in patients suffering from cartilage defects, as untreated defects often lead to osteoarthritis. Within the last two decades, tissue engineering based [...] Read more.

Cartilage defects in the knee are often seen in young and active patients. There is a need for effective joint preserving treatments in patients suffering from cartilage defects, as untreated defects often lead to osteoarthritis. Within the last two decades, tissue engineering based techniques using a wide variety of polymers, cell sources, and signaling molecules have been evaluated. We start this review with basic background information on cartilage structure, its intrinsic repair, and an overview of the cartilage repair treatments from a historical perspective. Next, we thoroughly discuss polymer construct components and their current use in commercially available constructs. Finally, we provide an in-depth discussion about construct considerations such as degradation rates, cell sources, mechanical properties, joint homeostasis, and non-degradable/hybrid resurfacing techniques. As future prospects in cartilage repair, we foresee developments in three areas: first, further optimization of degradable scaffolds towards more biomimetic grafts and improved joint environment. Second, we predict that patient-specific non-degradable resurfacing implants will become increasingly applied and will provide a feasible treatment for older patients or failed regenerative treatments. Third, we foresee an increase of interest in hybrid construct, which combines degradable with non-degradable materials. Full article

(This article belongs to the Special Issue Functional Polymers for Medical Applications)

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1381 KiB

Open AccessReview

Functionalized Polymers for Enhance Oral Bioavailability of Sensitive Molecules

by Yolanda Alvarado Pérez, Claudia Muro Urista, Javier Illescas Martínez, María Del Carmen Díaz Nava and Francisco A. Riera Rodríguez

Polymers 2016, 8(6), 214; https://doi.org/10.3390/polym8060214 - 02 Jun 2016

Cited by 25 | Viewed by 6515

Abstract

Currently, many sensitive molecules have been studied for effective oral administration. These substances are biologically active compounds that mainly suffer early degradation in the gastrointestinal tract (GIT) and physicochemical instability, inactivation and poor solubility and permeability. The sensibility of the biomolecules has limited [...] Read more.

Currently, many sensitive molecules have been studied for effective oral administration. These substances are biologically active compounds that mainly suffer early degradation in the gastrointestinal tract (GIT) and physicochemical instability, inactivation and poor solubility and permeability. The sensibility of the biomolecules has limited their oral administration in the body and today is an important research topic to achieve desired effects in medicine field. Under this perspective, various enhancement approaches have been studied as alternatives to increase their oral bioavailability. Some of these strategies include functionalized polymers to provide specific useful benefits as protection to the intestinal tract by preventing its degradation by stomach enzymes, to increase their absorption, permeability, stability, and to make a proper release in the GIT. Due to specific chemical groups, shapes and sizes, morphologies, mechanical properties, and degradation, recent advances in functionalized polymers have opened the door to great possibilities to improve the physicochemical characteristics of these biopharmaceuticals. Today, many biomolecules are found in basic studies, preclinical steps, and others are late stage clinical development. This review summarizes the contribution of functionalized polymers to enhance oral bioavailability of sensitive molecules and their application status in medicine for different diseases. Future trends of these polymers and their possible uses to achieve different formulation goals for oral delivery are also covered in this manuscript. Full article

(This article belongs to the Special Issue Functional Polymers for Medical Applications)

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3486 KiB

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Electro-Active Polymers (EAPs): A Promising Route to Design Bio-Organic/Bioinspired Platforms with on Demand Functionalities

by Vincenzo Guarino, Simona Zuppolini, Anna Borriello and Luigi Ambrosio

Polymers 2016, 8(5), 185; https://doi.org/10.3390/polym8050185 - 09 May 2016

Cited by 60 | Viewed by 10450

Abstract

Through recent discoveries and new knowledge among correlations between molecular biology and materials science, it is a growing interest to design new biomaterials able to interact—i.e., to influence, to guide or to detect—with cells and their surrounding microenvironments, in order to [...] Read more.

Through recent discoveries and new knowledge among correlations between molecular biology and materials science, it is a growing interest to design new biomaterials able to interact—i.e., to influence, to guide or to detect—with cells and their surrounding microenvironments, in order to better control biological phenomena. In this context, electro-active polymers (EAPs) are showing great promise as biomaterials acting as an interface between electronics and biology. This is ascribable to the highly tunability of chemical/physical properties which confer them different conductive properties for various applicative uses (i.e., molecular targeting, biosensors, biocompatible scaffolds). This review article is divided into three parts: the first one is an overview on EAPs to introduce basic conductivity mechanisms and their classification. The second one is focused on the description of most common processes used to manipulate EAPs in the form of two-dimensional (2D) and three-dimensional (3D) materials. The last part addresses their use in current applications in different biomedical research areas including tissue engineering, biosensors and molecular delivery. Full article

(This article belongs to the Special Issue Functional Polymers for Medical Applications)

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3756 KiB

Open AccessReview

Polymeric Biodegradable Stent Insertion in the Esophagus

by Kai Yang, Christopher Ling, Tianwen Yuan, Yueqi Zhu, Yingsheng Cheng and Wenguo Cui

Polymers 2016, 8(5), 158; https://doi.org/10.3390/polym8050158 - 26 Apr 2016

Cited by 10 | Viewed by 13246

Abstract

Esophageal stent insertion has been used as a well-accepted and effective alternative to manage and improve the quality of life for patients diagnosed with esophageal diseases and disorders. Current stents are either permanent or temporary and are fabricated from either metal or plastic. [...] Read more.

Esophageal stent insertion has been used as a well-accepted and effective alternative to manage and improve the quality of life for patients diagnosed with esophageal diseases and disorders. Current stents are either permanent or temporary and are fabricated from either metal or plastic. The partially covered self-expanding metal stent (SEMS) has a firm anchoring effect and prevent stent migration, however, the hyperplastic tissue reaction cause stent restenosis and make it difficult to remove. A fully covered SEMS and self-expanding plastic stent (SEPS) reduced reactive hyperplasia but has a high migration rate. The main advantage that polymeric biodegradable stents (BDSs) have over metal or plastic stents is that removal is not require and reduce the need for repeated stent insertion. But the slightly lower radial force of BDS may be its main shortcoming and a post-implant problem. Thus, strengthening support of BDS is a content of the research in the future. BDSs are often temporarily effective in esophageal stricture to relieve dysphagia. In the future, it can be expect that biodegradable drug-eluting stents (DES) will be available to treat benign esophageal stricture, perforations or leaks with additional use as palliative modalities for treating malignant esophageal stricture, as the bridge to surgery or to maintain luminal patency during neoadjuvant chemoradiation. Full article

(This article belongs to the Special Issue Functional Polymers for Medical Applications)

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1426 KiB

Open AccessReview

Biodegradable Polymer Membranes Applied in Guided Bone/Tissue Regeneration: A Review

by Jiaolong Wang, Lina Wang, Ziyu Zhou, Hanjian Lai, Pan Xu, Lan Liao and Junchao Wei

Polymers 2016, 8(4), 115; https://doi.org/10.3390/polym8040115 - 29 Mar 2016

Cited by 237 | Viewed by 21589

Abstract

Polymer membranes have been widely used in guided tissue regeneration (GTR) and guided bone regeneration (GBR). In this review, various commercially available membranes are described. Much attention is paid to the recent development of biodegradable polymers applied in GTR and GBR, and the [...] Read more.

Polymer membranes have been widely used in guided tissue regeneration (GTR) and guided bone regeneration (GBR). In this review, various commercially available membranes are described. Much attention is paid to the recent development of biodegradable polymers applied in GTR and GBR, and the important issues of biodegradable polymeric membranes, including their classification, latest experimental research and clinical applications, as well as their main challenges are addressed. Herein, natural polymers, synthetic polymers and their blends are all introduced. Pure polymer membranes are biodegradable and biocompatible, but they lack special properties such as antibacterial properties, osteoconductivity, and thus polymer membranes loaded with functional materials such as antibacterial agents and growth factors show many more advantages and have also been introduced in this review. Despite there still being complaints about polymer membranes, such as their low mechanical properties, uncontrollable degradation speed and some other drawbacks, these problems will undoubtedly be conquered and biodegradable polymers will have more applications in GTR and GBR. Full article

(This article belongs to the Special Issue Functional Polymers for Medical Applications)

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1566 KiB

Open AccessReview

Drug Delivery Systems Obtained from Silica Based Organic-Inorganic Hybrids

by João Augusto Oshiro Junior, Marina Paiva Abuçafy, Eloísa Berbel Manaia, Bruna Lallo da Silva, Bruna Galdorfini Chiari-Andréo and Leila Aparecida Chiavacci

Polymers 2016, 8(4), 91; https://doi.org/10.3390/polym8040091 - 24 Mar 2016

Cited by 44 | Viewed by 7686

Abstract

This is a review of hybrid materials based on silica as an inorganic phase used as drug delivery systems (DDS). Silica based DDS have shown effectivity when compared with traditional delivery systems. They present advantages such as: (a) ability to maintain the therapeutic [...] Read more.

This is a review of hybrid materials based on silica as an inorganic phase used as drug delivery systems (DDS). Silica based DDS have shown effectivity when compared with traditional delivery systems. They present advantages such as: (a) ability to maintain the therapeutic range with minor variations; (b) prevention of local and systemic toxic effects; (c) plasma concentrations increase of substances with a short half-life; and (d) reduction of the number of daily doses, which may increase patient adherence to the treatment. These advantages occur due to the physical, chemical and optical properties of these materials. Therefore, we discuss the properties and characteristics of them and we present some applications, using different approaches of DDS to ensure therapeutic effectiveness and side effects reduction such as implantable biomaterial, film-forming materials, stimuli-responsive systems and others. Full article

(This article belongs to the Special Issue Functional Polymers for Medical Applications)

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14623 KiB

Open AccessReview

Switchable Materials Containing Polyzwitterion Moieties

by Markéta Ilčíková, Ján Tkáč and Peter Kasák

Polymers 2015, 7(11), 2344-2370; https://doi.org/10.3390/polym7111518 - 20 Nov 2015

Cited by 68 | Viewed by 11719

Abstract

In recent decades, the design and construction of smart materials capable of switching into a polyzwitterionic state by an external trigger have been intensively pursued. Polyzwitterionic states have unique antifouling and surface properties and external triggers, such as pH, light, ions, electric field [...] Read more.

In recent decades, the design and construction of smart materials capable of switching into a polyzwitterionic state by an external trigger have been intensively pursued. Polyzwitterionic states have unique antifouling and surface properties and external triggers, such as pH, light, ions, electric field and CO₂, cause significant changes in materials with regard to overall charge, ionic strength and wettability. This survey highlights current progress in the irreversible as well as the reversible switching process involving polyzwitterionic moieties, which can, in turn, be applied to studying the interaction of various interfaces with biological species as protein, DNA, bacteria or platelets and also for advanced use. Full article

(This article belongs to the Special Issue Functional Polymers for Medical Applications)

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