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Polymers
Special Issues
Polymers and Polymeric Nanoparticles for Therapy and Imaging
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Polymers and Polymeric Nanoparticles for Therapy and Imaging

A special issue of Polymers (ISSN 2073-4360).

Deadline for manuscript submissions: closed (31 May 2015) | Viewed by 40115

Special Issue Editors

Prof. Dr. Cyrille Boyer

grade E-Mail Website
Guest Editor
School of Chemical Engineering, University of New South Wales (UNSW), Sydney, NSW 2052, Australia
Interests: photoredox chemistry; photopolymerization; functional polymers; nanomedicine
Special Issues, Collections and Topics in MDPI journals
Prof. Dr. Andrew Whittaker

E-Mail Website
Guest Editor
Australian Institute for Bioengineering and Nanotechnology, The University of Queensland, Brisbane, QLD 4072, Australia
Interests: imaging; theranostic; gene delivery; MRI

Special Issue Information

Dear Colleagues,

Functional polymeric nanoparticles with controlled size, morphology, and precise placement of functional groups have attracted significant attention, and various methodologies enabling their synthesis have recently emerged. Such nano-materials are finding significant and diverse applications as drug/gene carriers and/or as contrast agents for imaging.

This Special Issue will be an international forum for researchers to discuss the most recent techniques for the preparation of these polymeric nanoparticles using the latest macromolecular engineering tools (such as click chemistry, self-assembled macromolecules and polymer synthesis) to yield well-defined functional nanoparticles with potential applications in the field of drug delivery and imaging. Through this issue, the synthesis of these nano-objects, as well as their applications in the design of new treatments, will be discussed by a broad range of authors.

Prof. Dr. Cyrille Boyer
Prof. Dr. Andrew Whittaker
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Polymers is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2700 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.


Keywords

  • nanomedicine
  • theranostic
  • imaging techniques, including magnetic resonance imaging (MRI), computer tomography (CT), positron emission tomography (PET);
  • siRNA and gene delivery
  • drug delivery
  • biomaterials
  • biopolymers
  • nanoparticles/ Nanotechnology
  • optical imaging
  • therapeutic applications of nanotechnology

Published Papers (5 papers)

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Research

3899 KiB  
Article
Synthesis of ABA Tri-Block Co-Polymer Magnetopolymersomes via Electroporation for Potential Medical Application
by Jennifer Bain, Matthew E. Berry, Catherine E. Dirks and Sarah S. Staniland
Polymers 2015, 7(12), 2558-2571; https://doi.org/10.3390/polym7121529 - 02 Dec 2015
Cited by 3 | Viewed by 8484
Abstract
The ABA tri-block copolymer poly(2-methyloxazoline)–poly(dimethylsiloxane)–poly(2-methyloxazoline) (PMOXA–PDMS–PMOXA) is known for its capacity to mimic a bilayer membrane in that it is able to form vesicular polymersome structures. For this reason, it is the subject of extensive research and enables the development of more robust, [...] Read more.
The ABA tri-block copolymer poly(2-methyloxazoline)–poly(dimethylsiloxane)–poly(2-methyloxazoline) (PMOXA–PDMS–PMOXA) is known for its capacity to mimic a bilayer membrane in that it is able to form vesicular polymersome structures. For this reason, it is the subject of extensive research and enables the development of more robust, adaptable and biocompatible alternatives to natural liposomes for biomedical applications. However, the poor solubility of this polymer renders published methods for forming vesicles unreproducible, hindering research and development of these polymersomes. Here we present an adapted, simpler method for the production of PMOXA–PDMS–PMOXA polymersomes of a narrow polydispersity (45 ± 5.8 nm), via slow addition of aqueous solution to a new solvent/polymer mixture. We then magnetically functionalise these polymersomes to form magnetopolymersomes via in situ precipitation of iron-oxide magnetic nanoparticles (MNPs) within the PMOXA–PDMS–PMOXA polymersome core and membrane. This is achieved using electroporation to open pores within the membrane and to activate the formation of MNPs. The thick PMOXA–PDMS–PMOXA membrane is well known to be relatively non-permeable when compared to more commonly used di-block polymer membranes due a distinct difference in both size and chemistry and therefore very difficult to penetrate using standard biological methods. This paper presents for the first time the application of electroporation to an ABA tri-block polymersome membrane (PMOXA–PDMS–PMOXA) for intravesicular in situ precipitation of uniform MNPs (2.6 ± 0.5 nm). The electroporation process facilitates the transport of MNP reactants across the membrane yielding in situ precipitation of MNPs. Further to differences in length and chemistry, a tri-block polymersome membrane structure differs from a natural lipid or di-block polymer membrane and as such the application and effects of electroporation on this type of polymersome is entirely novel. A mechanism is hypothesised to explain the final structure and composition of these biomedically applicable tri-block magnetopolymersomes. Full article
(This article belongs to the Special Issue Polymers and Polymeric Nanoparticles for Therapy and Imaging)
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1218 KiB  
Communication
pH-Dependent Release of Insulin from Layer-by-Layer-Deposited Polyelectrolyte Microcapsules
by Kentaro Yoshida, Tetsuya Ono, Yoshitomo Kashiwagi, Shigehiro Takahashi, Katsuhiko Sato and Jun-ichi Anzai
Polymers 2015, 7(7), 1269-1278; https://doi.org/10.3390/polym7071269 - 13 Jul 2015
Cited by 28 | Viewed by 7645
Abstract
Insulin-containing microcapsules were prepared by a layer-by-layer (LbL) deposition of poly(allylamine hydrochloride) (PAH) and polyanions, such as poly(styrenesulfonate) (PSS), poly(vinyl sulfate) (PVS), and dextran sulfate (DS) on insulin-containing calcium carbonate (CaCO3) microparticles. The CaCO3 core was dissolved in diluted HCl [...] Read more.
Insulin-containing microcapsules were prepared by a layer-by-layer (LbL) deposition of poly(allylamine hydrochloride) (PAH) and polyanions, such as poly(styrenesulfonate) (PSS), poly(vinyl sulfate) (PVS), and dextran sulfate (DS) on insulin-containing calcium carbonate (CaCO3) microparticles. The CaCO3 core was dissolved in diluted HCl solution to obtain insulin-containing hollow microcapsules. The microcapsules were characterized by scanning electron microscope (SEM) and atomic force microscope (AFM) images and ζ-potential. The release of insulin from the microcapsules was faster at pH 9.0 and 7.4 than in acidic solutions due to the different charge density of PAH. In addition, insulin release was suppressed when the microcapsules were constructed using PAH with a lower molecular weight, probably owing to a thicker shell of the microcapsules. The results suggested a potential use of the insulin-containing microcapsules for developing insulin delivery systems. Full article
(This article belongs to the Special Issue Polymers and Polymeric Nanoparticles for Therapy and Imaging)
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3024 KiB  
Article
A Novel Melt-Dispersion Technique for Simplistic Preparation of Chlorpromazine-Loaded Polycaprolactone Nanocapsules
by Thiresen Govender, Yahya E. Choonara, Pradeep Kumar, Lisa C. Du Toit, Girish Modi, Dinesh Naidoo and Viness Pillay
Polymers 2015, 7(6), 1145-1176; https://doi.org/10.3390/polym7061145 - 19 Jun 2015
Cited by 16 | Viewed by 7343
Abstract
The aim of this study was to design, synthesize and optimize chlorpromazine hydrochloride (CPZ)-loaded, poly-ε-caprolactone (PCL) based nanocapsules, intended for site specific delivery to the frontal lobe, using a novel melt-dispersion technique that is non-arduous, inexpensive and devoid of any hazardous organic solvents. [...] Read more.
The aim of this study was to design, synthesize and optimize chlorpromazine hydrochloride (CPZ)-loaded, poly-ε-caprolactone (PCL) based nanocapsules, intended for site specific delivery to the frontal lobe, using a novel melt-dispersion technique that is non-arduous, inexpensive and devoid of any hazardous organic solvents. Experimental trials using a central composite design were performed on 13 statistically derived formulations of various combinations of PCL (1000–3000 mg) and Polysorbate 80 (2%–5% v/v) on the physicochemical and physicomechanical properties and interactive effects on PCL nanocapsule formulation. Differential scanning calorimetry (DSC), Temperature modulated differential scanning calorimetry (TMDSC) and Fourier transform infrared spectroscopy (FTIR) revealed that there was no thermodegardation of the constituents utilized in the melt dispersion technique. Nanocapsule yields achieved were very high however entrapment of CPZ proved to be relatively low due to the highly hydrophilic nature of CPZ and the processing of the nanocapsules post synthesis. Nanocapsule sizes were in the nanotherapeutic range and varied from 132.7 ± 6.8 nm to 566.6 ± 5.5 nm. Zeta potential ranged from 15.1 ± 0.65 mV to 28.8 ± 0.84 mV revealing capsules that were of incipient to moderate stability. Transmission electron microscopy revealed nanocapsules that were spherical shape, well individualized with a moderate degree of flocculation. In vitro CPZ release was biphasic for all formulations with an initial burst release followed by pseudo-steady controlled release over 30 days. The cytotoxicity of the optimized nanocapsule system on a PC12 neuronal cell line proved to be minimal. Following incorporation of the optimized nanocapsules within a polymeric membrane, in vivo implantation of the device in a New Zealand Albino rabbit model proved the efficacy of the system in achieving prolonged more targeted CPZ levels to the brain. Extensive in vitro testing and optimization and preclinical evaluation supports the application for the use and feasibility of the CPZ-loaded, PCL based nanocapsules for the long-term management of certain psychotropic disorders where the benefits of nanotechnology can be exploited. Full article
(This article belongs to the Special Issue Polymers and Polymeric Nanoparticles for Therapy and Imaging)
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1243 KiB  
Article
Addition of Zinc Improves the Physical Stability of Insulin in the Primary Emulsification Step of the Poly(lactide-co-glycolide) Microsphere Preparation Process
by Chandrasekar Manoharan and Jagdish Singh
Polymers 2015, 7(5), 836-850; https://doi.org/10.3390/polym7050836 - 28 Apr 2015
Cited by 10 | Viewed by 6887
Abstract
In this study, the effect of zinc on insulin stability during the primary emulsification step of poly(lactide-co-glycolide) microspheres preparation by the water-in-oil-in-water (w/o/w) double emulsion solvent evaporation technique was evaluated. Insulin was emulsified at homogenization speeds of 5000 and 10,000 rpm. [...] Read more.
In this study, the effect of zinc on insulin stability during the primary emulsification step of poly(lactide-co-glycolide) microspheres preparation by the water-in-oil-in-water (w/o/w) double emulsion solvent evaporation technique was evaluated. Insulin was emulsified at homogenization speeds of 5000 and 10,000 rpm. Insulin was extracted from the primary w/o emulsion by a method previously reported from our laboratory and analyzed by comprehensive analytical techniques. The differential scanning calorimetry thermograms of insulin with zinc showed a single peak around 83 °C with calorimetric enthalpy values similar to native insulin. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) of extracted insulin showed a single intense band around 6 kDa, demonstrating the preservation of primary structure. High performance liquid chromatography (HPLC) analysis revealed that no degradation products were formed during the homogenization process. Insulin aggregates residing at the w/o interfaces were found to be of non-covalent nature. In addition, observation of a single characteristic peak for insulin at m/z 5808 in the matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrum confirmed the absence of insulin degradation products and covalent dimers. Presence of zinc preserved the secondary structure of insulin as indicated by circular dichroism. In conclusion, these results show that with the addition of zinc, insulin stability can be improved during the primary emulsification step. Full article
(This article belongs to the Special Issue Polymers and Polymeric Nanoparticles for Therapy and Imaging)
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5479 KiB  
Article
Synthesis of Mannosylated Polyethylenimine and Its Potential Application as Cell-Targeting Non-Viral Vector for Gene Therapy
by Ying Hu, Bei-Hua Xu, Jiao-Jiao Xu, Dan Shou and Jian-Qing Gao
Polymers 2014, 6(10), 2573-2587; https://doi.org/10.3390/polym6102573 - 17 Oct 2014
Cited by 13 | Viewed by 9004
Abstract
Mannose polyethylenimine with a molecular weight of 25 k (Man-PEI25k) was synthesized via a phenylisothiocyanate bridge using mannopyranosylphenyl isothiocyanate as a coupling reagent, and characterized by 1H NMR (nuclear magnetic resonance) and FT-IR (Fourier transform infrared spectroscopy) analysis. Spherical nanoparticles [...] Read more.
Mannose polyethylenimine with a molecular weight of 25 k (Man-PEI25k) was synthesized via a phenylisothiocyanate bridge using mannopyranosylphenyl isothiocyanate as a coupling reagent, and characterized by 1H NMR (nuclear magnetic resonance) and FT-IR (Fourier transform infrared spectroscopy) analysis. Spherical nanoparticles were formed with diameters of 80–250 nm when the copolymer was mixed with DNA at various charge ratios of copolymer/DNA (N/P). Gel electrophoresis demonstrated that the DNA had been condensed and retained by the PEI derivates at low N/P ratios. The Man-PEI25k/DNA complexes were less cytotoxic than the PEI complexes with a molecular weight of 25 k (PEI25k) at the same N/P ratio. Laser scan confocal microscopy and flow cytometry confirmed that the Man-PEI25k/DNA complexes gave higher cell uptake efficiency in (Dendritic cells) DC2.4 cells than HeLa cells. The transfection efficiency of Man-PEI25k was higher than that of PEI25k towards DC2.4 cells. These results indicated that Man-PEI25k could be used as a potential DC-targeting non-viral vector for gene therapy. Full article
(This article belongs to the Special Issue Polymers and Polymeric Nanoparticles for Therapy and Imaging)
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