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Special Issue "Macromolecules Applied to Pharmaceutics"

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A special issue of Molecules (ISSN 1420-3049). This special issue belongs to the section "Medicinal Chemistry".

Deadline for manuscript submissions: closed (30 June 2009)

Special Issue Editor

Guest Editor
Prof. Dr. Tommasina Coviello (Website)

Faculty of Pharmacy and Medicine, Department of Drug Chemistry and Technologies, "Sapienza" University of Rome, P.le A. Moro 5, 00185 Rome, Italy
Fax: +39 0649913133
Interests: polysaccharides; hydrogel; rheology; texture analysis; modified drug delivery

Special Issue Information

Dear Colleagues,

This special issue, “Macromolecules applied to Pharmaceutics” is devoted to a peculiar branch of polymer science that is rapidly growing in the last decades.
It is of interest, therefore, to publish both reviews and original research papers to illustrate the general trend in current research.
Polymers can act, in different ways, as carriers for drug delivery and as peculiar therapeutic agents to be delivered. In the past few decades macromolecules have evolved from off-the-shelf materials originally developed for applications unrelated to biomedicine to materials specifically designed for particular applications and exhibiting intended biomedical functions. The design of new polymeric devices requires the combination of knowledge among scientist from different fields such biology, medicine, pharmaceutical sciences, chemistry, physics and materials science.
In that sense I wish to thank all the authors for their cooperation and support in the preparation of the present issue.

Prof. Dr. Tommasina Coviello
Guest Editor

Keywords

  • Synthetic and natural polymers for drug/gene delivery and/or medical devices
  • New aspects of macromolecule uses in the dosage form design
  • Characterization of polymers used in the pharmaceutics field
  • Biomaterials
  • Macromolecular pro-drugs
  • Delivery of macromolecular drugs
  • Hydrogel delivery systems
  • Micro- and Nano-technological approaches for the delivery of macromolecules
  • Pharmaceutical applications of dendrimers
  • Polymeric nanocarriers for drug delivery
  • Polymer-drug conjugates for drug targeting
  • Stimuli-responsive polymeric systems for biomedical applications
  • Polymeric scaffolds for tissue engineering

Published Papers (12 papers)

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Research

Jump to: Review

Open AccessArticle Antimicrobial Activity of Geranium Oil against Clinical Strains of Staphylococcus aureus
Molecules 2012, 17(9), 10276-10291; doi:10.3390/molecules170910276
Received: 28 June 2012 / Revised: 12 August 2012 / Accepted: 14 August 2012 / Published: 28 August 2012
Cited by 10 | PDF Full-text (241 KB)
Abstract
The aim of this work was to investigate the antibacterial properties of geranium oil obtained from Pelargonium graveolens Ait. (family Geraniaceae), against one standard S. aureus strain ATCC 433000 and seventy clinical S. aureus strains. The agar dilution method was used [...] Read more.
The aim of this work was to investigate the antibacterial properties of geranium oil obtained from Pelargonium graveolens Ait. (family Geraniaceae), against one standard S. aureus strain ATCC 433000 and seventy clinical S. aureus strains. The agar dilution method was used for assessment of bacterial growth inhibition at various concentrations of geranium oil. Susceptibility testing of the clinical strains to antibiotics was carried out using the disk-diffusion and E-test methods. The results of our experiment showed that the oil from P. graveolens has strong activity against all of the clinical S. aureus isolates—including multidrug resistant strains, MRSA strains and MLSB-positive strains—exhibiting MIC values of 0.25–2.50 μL/mL. Full article
(This article belongs to the Special Issue Macromolecules Applied to Pharmaceutics)
Open AccessArticle Characterization and Dissolution Study of Chitosan Freeze-Dried Systems for Drug Controlled Release
Molecules 2009, 14(11), 4370-4386; doi:10.3390/molecules14114370
Received: 8 September 2009 / Revised: 14 October 2009 / Accepted: 28 October 2009 / Published: 30 October 2009
Cited by 14 | PDF Full-text (768 KB)
Abstract
Freeze-dried systems (L) comprising chitosan (CS) and caffeine (CAF) have been developed for oral administration. Different proportions of CS and CAF have been used in the preparation of the systems. Hot stage microscopy (HSM), differential scanning calorimetry (DSC) and X-ray diffraction powder [...] Read more.
Freeze-dried systems (L) comprising chitosan (CS) and caffeine (CAF) have been developed for oral administration. Different proportions of CS and CAF have been used in the preparation of the systems. Hot stage microscopy (HSM), differential scanning calorimetry (DSC) and X-ray diffraction powder have been used to characterize the systems prepared. X-ray diffraction patterns showed that there were no interactions between CAF and CS molecules within the freeze-dried systems and the crystallinity of CAF was decreased. Swelling and dissolution tests were carried out in two different media (demineralized water and pH progressive medium) in order to establish their influence over CAF/CS system behaviour. Characteristic swelling behaviour of freeze-dried CS systems (imbibition and dissolution processes) was influenced by the proportions of CS and CAF in the formulations, and by the nature of the medium due to the pH-dependent solubility of CS. Release of CAF from lyophilized systems was conditioned by the swelling process and it should be possible to obtain a CAF/CS binary system with a specific time for total drug release including concrete proportions of both components. Furthermore, the freeze-drying process allowed us to obtain feasible systems for controlled release of CAF until the total amount of drug was released. Full article
(This article belongs to the Special Issue Macromolecules Applied to Pharmaceutics)
Open AccessArticle Adding Chemical Cross-Links to a Physical Hydrogel
Molecules 2009, 14(9), 3662-3675; doi:10.3390/molecules14093662
Received: 30 June 2009 / Revised: 27 August 2009 / Accepted: 16 September 2009 / Published: 17 September 2009
Cited by 6 | PDF Full-text (711 KB)
Abstract
Synergistic hydrogels are often encountered in polysaccharide mixtures widely used in food and biopharma products. The xanthan and konjac glucomannan pair provides one of the most studied synergistic hydrogels. Recently we showed that the junction zones stabilizing the 3D structure of this [...] Read more.
Synergistic hydrogels are often encountered in polysaccharide mixtures widely used in food and biopharma products. The xanthan and konjac glucomannan pair provides one of the most studied synergistic hydrogels. Recently we showed that the junction zones stabilizing the 3D structure of this gel are present as macromolecular complexes in solution formed by the partially depolymerised polysaccharidic chains. The non-covalent interactions stabilizing the structure of the polysaccharidic complex cause the melting of the ordered structure of the complex in the solution and of the hydrogels. Introduction of chemical cross-links in the 3D structure of the synergistic hydrogel removes this behaviour, adding new features to the swelling and to the viscoelastic properties of the cured hydrogel. The use of epichlorohydrin as low molecular weight cross-linker does not impact unfavourably on the viability of NIH 3T3 fibroblasts. Full article
(This article belongs to the Special Issue Macromolecules Applied to Pharmaceutics)
Figures

Open AccessArticle Preparation and Characterization of Novel Gellan Gum Hydrogels Suitable for Modified Drug Release
Molecules 2009, 14(9), 3376-3391; doi:10.3390/molecules14093376
Received: 26 June 2009 / Revised: 30 July 2009 / Accepted: 31 August 2009 / Published: 3 September 2009
Cited by 30 | PDF Full-text (476 KB)
Abstract
Innovative hydrogels obtained by physical and chemical crosslinking of deacylated Gellan gum have been characterized in terms of water uptake, rheological properties and compressibility, and the behaviour of the tested materials, according to the type of the obtained network, is thoroughly discussed. [...] Read more.
Innovative hydrogels obtained by physical and chemical crosslinking of deacylated Gellan gum have been characterized in terms of water uptake, rheological properties and compressibility, and the behaviour of the tested materials, according to the type of the obtained network, is thoroughly discussed. The release from the various gels of loaded model molecules of different steric hindrance was also investigated and the trend of the release profiles has been related to the structures proposed for the physical and the chemical hydrogel. Full article
(This article belongs to the Special Issue Macromolecules Applied to Pharmaceutics)
Figures

Open AccessArticle Structural Characterization of Calcium Alginate Matrices by Means of Mechanical and Release Tests
Molecules 2009, 14(8), 3003-3017; doi:10.3390/molecules14083003
Received: 25 June 2009 / Revised: 4 August 2009 / Accepted: 10 August 2009 / Published: 12 August 2009
Cited by 9 | PDF Full-text (234 KB) | HTML Full-text | XML Full-text
Abstract
In this paper we have concentrated on the characterization of calcium alginate hydrogels loaded with a model drug (myoglobin) by means of a mechanical approach; in addition, release tests of myoglobin from alginate hydrogels were performed. At a fixed temperature, relaxation tests [...] Read more.
In this paper we have concentrated on the characterization of calcium alginate hydrogels loaded with a model drug (myoglobin) by means of a mechanical approach; in addition, release tests of myoglobin from alginate hydrogels were performed. At a fixed temperature, relaxation tests (mechanical study) were carried out on matrices constituted by different polymer concentrations. The interpretation of the relaxation behavior of the different matrices was conducted using the generalized Maxwell model; as a result of this investigation it was possible to conclude that for polymer concentrations greater than 0.5 g/ 100 mL the matrices behaved as solid materials. In addition, it was observed that the mechanical properties of the matrices increased with polymer concentration. With regard to the release tests, the diffusion coefficient of myoglobin in the matrix in relation to polymer concentrations was determined. The mechanical and release data where then analyzed by Flory’s theory and by a modified free-volume theory, respectively, to estimate the network mesh size ξ. The comparison between the mesh sizes obtained by the two approaches showed a satisfactory agreement for polymer concentrations greater than 0.5 g/100 mL. It should be noted that the approach proposed here to determine the polymeric network meshes is absolutely general and can be advantageously applied to the characterization of other similar polymeric systems. Full article
(This article belongs to the Special Issue Macromolecules Applied to Pharmaceutics)
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Open AccessArticle Physical Carboxymethylscleroglucan/Calcium Ion Hydrogels as Modified Drug Delivery Systems in Topical Formulations
Molecules 2009, 14(8), 2684-2698; doi:10.3390/molecules14082684
Received: 29 June 2009 / Revised: 16 July 2009 / Accepted: 21 July 2009 / Published: 24 July 2009
Cited by 9 | PDF Full-text (417 KB)
Abstract
A carboxymethyl derivative of scleroglucan (Scl-CM) with a 65±5% carboxylic group degree of derivatization (DD) was recently synthesized and characterized. Aqueous solutions of the polymer underwent to a sharp transition toward a gel like behaviour in the presence of divalent ions such [...] Read more.
A carboxymethyl derivative of scleroglucan (Scl-CM) with a 65±5% carboxylic group degree of derivatization (DD) was recently synthesized and characterized. Aqueous solutions of the polymer underwent to a sharp transition toward a gel like behaviour in the presence of divalent ions such as Ca+2. Physical hydrogels with different Scl-CM/Ca+2 ratios were prepared and characterized for their rheological behaviour. Their potential as drug delivery systems was also evaluated. To this end three non steroidal anti-inflammatory drugs (NSAIDs) were loaded into the hydrogels obtained with 2% w/v solution of Scl-CM and 0.05 and 0.1 M CaCl2. The release rate of the drugs was critically related to the salt concentration. By an appropriate combination of the hydrogels prepared using different amounts of salt, it was possible to obtain a system able to release diclofenac with zero-order kinetics. Primary skin irritation tests showed a good biocompatibility of the new polymer, as well as of its hydrogels. These results suggest a potential of the new hydrogels for the development of modified delivery systems in topical formulations. Full article
(This article belongs to the Special Issue Macromolecules Applied to Pharmaceutics)
Open AccessArticle Influence of Different Polymer Types on the Overall Release Mechanism in Hydrophilic Matrix Tablets
Molecules 2009, 14(8), 2699-2716; doi:10.3390/molecules14082699
Received: 25 June 2009 / Revised: 10 July 2009 / Accepted: 15 July 2009 / Published: 24 July 2009
Cited by 7 | PDF Full-text (536 KB)
Abstract
The effect of three different types of polymer chain structures on the polymer release from hydrophilic matrix tablets was investigated by comparing a synthetic semi-crystalline linear polymer (PEO), a branched amorphous polysaccharide (dextran) and an amorphous substituted cellulose derivative (HPMC). The polymer [...] Read more.
The effect of three different types of polymer chain structures on the polymer release from hydrophilic matrix tablets was investigated by comparing a synthetic semi-crystalline linear polymer (PEO), a branched amorphous polysaccharide (dextran) and an amorphous substituted cellulose derivative (HPMC). The polymer release rates for tablets containing mixtures of high and low molecular weight grades in different ratios were determined by using a modified USP II method and a SEC-RI chromatography system. The results showed that independent of polymer type: (i) plots of the release versus time had similar shapes, (ii) the release of long and short polymer chains was equal and no fractionation occurred during the release and (iii) the release rate could be related to the average intrinsic viscosity of the polymer mixtures. This confirms the hypothesis that the release rate can be related to a constant viscosity on the surface of the hydrophilic matrix tablet and that it is valid for all the investigated polymers. Full article
(This article belongs to the Special Issue Macromolecules Applied to Pharmaceutics)
Open AccessArticle Novel Biodegradable Polyesters. Synthesis and Application as Drug Carriers for the Preparation of Raloxifene HCl Loaded Nanoparticles
Molecules 2009, 14(7), 2410-2430; doi:10.3390/molecules14072410
Received: 5 June 2009 / Revised: 2 July 2009 / Accepted: 6 July 2009 / Published: 7 July 2009
Cited by 16 | PDF Full-text (549 KB) | HTML Full-text | XML Full-text
Abstract
Raloxifene HCl is a drug with poor bioavailability and poor water solubility. Furthermore nο pharmaceutically acceptable organic solvent has been reported before to dilute the drug. It was observed that Raloxifene HCl can be diluted in a solvent mixture of acetone/water or [...] Read more.
Raloxifene HCl is a drug with poor bioavailability and poor water solubility. Furthermore nο pharmaceutically acceptable organic solvent has been reported before to dilute the drug. It was observed that Raloxifene HCl can be diluted in a solvent mixture of acetone/water or ethanol/water. The aim of this study was to use biodegradable polymers in order to prepare Raloxifene HCl nanoparticles. For this purpose a series of novel biodegradable poly(ethylene succinate-co-propylene adipate) P(ESu-co-PAd) polyesters were synthesized following the polycondensation method and further, poly(ethylene succinate) (PESu) and poly(propylene adipate) (PPAd) were used. The prepared polyesters were characterized by intrinsic viscosity measurements, end group analysis, enzymatic hydrolysis, Nuclear Magnetic Resonance Spectroscopy (1Η-NMR and 13C-NMR) and Wide-angle X-ray Diffractometry (WAXD). The drug nanoparticles have been prepared by a variation of the co-precipitation method and were studied by Wide-angle X-ray Diffractometry (WAXD), FTIR spectrometry, light scattering size distribution, Scanning Electron Microscopy (SEM) and release behavior measurements. The interactions between the polymers and the drug seem to be limited, so the drug occurs in crystalline form in all nanoparticles. The size of the nanoparticles seems to be in the range of 150-350 nm, depending on the polymer that was used. The drug release depends on the melting point and degree of crystallinity of the polyesters used. An initial high release rate was recorded followed by very slow rates of controlled release. Full article
(This article belongs to the Special Issue Macromolecules Applied to Pharmaceutics)
Open AccessArticle Application of Thermally Responsive Elastin-like Polypeptide Fused to a Lactoferrin-derived Peptide for Treatment of Pancreatic Cancer
Molecules 2009, 14(6), 1999-2015; doi:10.3390/molecules14061999
Received: 11 May 2009 / Revised: 31 May 2009 / Accepted: 3 June 2009 / Published: 4 June 2009
Cited by 35 | PDF Full-text (188 KB) | HTML Full-text | XML Full-text
Abstract
A well characterized, peptide derivative of bovine lactoferrin, L12, has been shown to possess anticancer properties in multiple cell lines. However, adverse side effects in normal tissues and poor plasma kinetics that hinder the clinical effectiveness of current chemotherapeutics also deter the [...] Read more.
A well characterized, peptide derivative of bovine lactoferrin, L12, has been shown to possess anticancer properties in multiple cell lines. However, adverse side effects in normal tissues and poor plasma kinetics that hinder the clinical effectiveness of current chemotherapeutics also deter the potential for effective delivery of this L12 peptide. To overcome these limitations, we have developed an Elastin-like polypeptide (ELP) carrier that has the potential to thermally target therapeutic peptides and chemotherapeutics to a tumor site. The coding sequence of ELP was modified with the L12 peptide at the C-terminus and a membrane transduction domain derived from the HIV-1 Tat protein at the N-terminus (Tat-ELP-L12). The thermally responsive Tat-ELP1-L12 is soluble in aqueous solutions at 37°C but aggregates near 41°C, which makes Tat-ELP1-L12 ideal for targeting to solid tumors on application of focused hyperthermia. We observed that under hyperthermia conditions at 42°C, Tat-ELP1-L12 mediated cytotoxicity in MIA PaCa-2 pancreatic adenocarcinoma cells was enhanced by nearly thirty-fold. We investigated the mechanisms of cell death and found evidence of mitochondrial membrane depolarization and caspase activation, which are characteristic of apoptosis, as well as, increased membrane permeability, as shown by LDH release. These results suggest that Tat-ELP1-L12 possesses cytotoxic properties to cancer cells in vitro and may have the potential to provide an effective vehicle to thermally target solid tumors. Full article
(This article belongs to the Special Issue Macromolecules Applied to Pharmaceutics)

Review

Jump to: Research

Open AccessReview Nasal Delivery of High Molecular Weight Drugs
Molecules 2009, 14(9), 3754-3779; doi:10.3390/molecules14093754
Received: 21 July 2009 / Revised: 14 September 2009 / Accepted: 17 September 2009 / Published: 23 September 2009
Cited by 42 | PDF Full-text (495 KB)
Abstract
Nasal drug delivery may be used for either local or systemic effects. Low molecular weight drugs with are rapidly absorbed through nasal mucosa. The main reasons for this are the high permeability, fairly wide absorption area, porous and thin endothelial basement membrane [...] Read more.
Nasal drug delivery may be used for either local or systemic effects. Low molecular weight drugs with are rapidly absorbed through nasal mucosa. The main reasons for this are the high permeability, fairly wide absorption area, porous and thin endothelial basement membrane of the nasal epithelium. Despite the many advantages of the nasal route, limitations such as the high molecular weight (HMW) of drugs may impede drug absorption through the nasal mucosa. Recent studies have focused particularly on the nasal application of HMW therapeutic agents such as peptide-protein drugs and vaccines intended for systemic effects. Due to their hydrophilic structure, the nasal bioavailability of peptide and protein drugs is normally less than 1%. Besides their weak mucosal membrane permeability and enzymatic degradation in nasal mucosa, these drugs are rapidly cleared from the nasal cavity after administration because of mucociliary clearance. There are many approaches for increasing the residence time of drug formulations in the nasal cavity resulting in enhanced drug absorption. In this review article, nasal route and transport mechanisms across the nasal mucosa will be briefly presented. In the second part, current studies regarding the nasal application of macromolecular drugs and vaccines with nanoand micro-particulate carrier systems will be summarised. Full article
(This article belongs to the Special Issue Macromolecules Applied to Pharmaceutics)
Open AccessReview Nano and Microtechnologies for the Delivery of Oligonucleotides with Gene Silencing Properties
Molecules 2009, 14(8), 2801-2823; doi:10.3390/molecules14082801
Received: 30 June 2009 / Revised: 22 July 2009 / Accepted: 27 July 2009 / Published: 29 July 2009
Cited by 29 | PDF Full-text (538 KB)
Abstract
Oligonucleotides (ONs) are synthetic fragments of nucleic acid designed to modulate the expression of target proteins. DNA-based ONs (antisense, antigene, aptamer or decoy) and more recently a new class of RNA-based ONs, the small interfering RNAs (siRNAs), have gained great attention for [...] Read more.
Oligonucleotides (ONs) are synthetic fragments of nucleic acid designed to modulate the expression of target proteins. DNA-based ONs (antisense, antigene, aptamer or decoy) and more recently a new class of RNA-based ONs, the small interfering RNAs (siRNAs), have gained great attention for the treatment of different disease states, such as viral infections, inflammation, diabetes, and cancer. However, the development of therapeutic strategies based on ONs is hampered by their low bioavailability, poor intracellular uptake and rapid degradation in biological fluids. The use of a non-viral carrier can be a powerful tool to overcome these drawbacks. Lipid or polymer-based nanotechnologies can improve biological stability and cellular uptake of ONs, with possibility of tissue and/or cellular targeting. The use of polymeric devices can also produce a prolonged release of the ON, thus reducing the need of frequent administrations. This review summarizes advantages and issues related to the main non-viral vectors used for ON delivery. Full article
(This article belongs to the Special Issue Macromolecules Applied to Pharmaceutics)
Open AccessReview Polymeric Plant-derived Excipients in Drug Delivery
Molecules 2009, 14(7), 2602-2620; doi:10.3390/molecules14072602
Received: 22 June 2009 / Revised: 1 July 2009 / Accepted: 6 July 2009 / Published: 16 July 2009
Cited by 97 | PDF Full-text (324 KB) | HTML Full-text | XML Full-text
Abstract
Drug dosage forms contain many components in addition to the active pharmaceutical ingredient(s) to assist in the manufacturing process as well as to optimise drug delivery. Due to advances in drug delivery technology, excipients are currently included in novel dosage forms to [...] Read more.
Drug dosage forms contain many components in addition to the active pharmaceutical ingredient(s) to assist in the manufacturing process as well as to optimise drug delivery. Due to advances in drug delivery technology, excipients are currently included in novel dosage forms to fulfil specific functions and in some cases they directly or indirectly influence the extent and/or rate of drug release and absorption. Since plant polysaccharides comply with many requirements expected of pharmaceutical excipients such as non-toxicity, stability, availability and renewability they are extensively investigated for use in the development of solid oral dosage forms. Furthermore, polysaccharides with varying physicochemical properties can be extracted from plants at relatively low cost and can be chemically modified to suit specific needs. As an example, many polysaccharide-rich plant materials are successfully used as matrix formers in modified release dosage forms. Some natural polysaccharides have even shown environmental-responsive gelation characteristics with the potential to control drug release according to specific therapeutic needs. This review discusses some of the most important plant-derived polymeric compounds that are used or investigated as excipients in drug delivery systems. Full article
(This article belongs to the Special Issue Macromolecules Applied to Pharmaceutics)

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