Functionalized Chitosan for Pharmaceutical Applications

WOS: 000416527500005Background: Chitosan structure versatility toward a change in an external stimulus represents a "must have" for the pharmaceutical applications, especially for the pharmaceutical formulations. Chemical modification can open new ways to obtain materials with tailored properties. Despite the great interest for conventional graft modifications, controlled/ living free radical polymerizations (i.e. RAFT, ATRP, etc.) and advanced chemistry techniques (i.e. click chemistry) seem more attractive nowadays and involve facile and fast procedure, high regioselectivity, quantitative yield, mild reaction conditions without generation of by-products. Objective: The present review provides a detailed state of art of the chemical modification of chitosan i.e. tailored side-chain functionalization using RAFT polymerization and click chemistry for specific applications within pharmaceutical formulations taking into account the applicative aspect regarding the need of pharmaceuticals. Conclusion: The review showed the routes of current approaches for side chain modification of chitosan including graft, block copolymers or other structural variations. The esterification of RAFT agents on chitosan by using carbonyl activating reagents enables producing chitosan graft and block copolymers with controlled architectures while the development of protection/ deprotection chemistry of chitosan made possible the regioselective modification of chitosan or other polysaccharides. Although these developments increased the potential of chitosan, still the chemical functionality and architectural diversity of the derivatives are limited. Application of modern techniques e.g. RAFT polymerization, "click" chemistry has opened new "doors" for the science of controlled and chemoselective synthesis of well-tailored derivatives with unique and superior properties.The Scientific and Technological Research Council of Turkey (TUBITAK) - Marie Curie Actions under FP7 [115C078]Authors acknowledge the financial support from "The Scientific and Technological Research Council of Turkey (TUBITAK), cofunded by Marie Curie Actions under FP7", project number 115C078

The Effect of Different Soft Core/Hard Shell Ratios on the Coating Performance of Acrylic Copolymer Latexes

Core-shell acrylic copolymer latexes containing bio resourced itaconic acid with different compositions in respect with the core and shell segments were synthesized, characterized, and applied as coating materials for leather. The purpose of the study was to evidence the high coating performance of the latexes when the ratio of the core/shell differed from 90/10 to 50/50 wt %. The copolymers were prepared via emulsion copolymerization technique and the products were isolated and characterized by means of structure identity, thermal behavior (DSC and DMTA), coating performance. The particle size of the latexes varied from 83 to 173 nm with the variation of the ratio of core/shell segments. The influence of the composition of soft part and hard part was highlighted in the thermal and coating properties. The optimal composition giving the best coating performance could be determined as DS 60/40. Further increase of the hard segment content, resulted in decreased emulsion stability and the coating performance on the leathers. The use of itaconic acid seemed to increase the emulsion stability as well the adhesion of the latexes to the substrate.SCIENTIFIC AND TECHNOLOGICAL RESEARCH COUNCIL OF TURKEY (TUBITAK)This research was funded by THE SCIENTIFIC AND TECHNOLOGICAL RESEARCH COUNCIL OF TURKEY (TUBITAK), grant number 115M650

Functionalization of chitosan by click chemistry

International Conference on Environment, Chemical Engineering and Materials (ECEM) -- JUN 27-29, 2017 -- Transylvania Univ Brasov, Brasov, ROMANIAWOS: 000426289700009Chitosan modification represents a challenge nowadays. The variety of compounds which can be obtained with various architectures and different functionalities made it attractive to be used in fields like pharmacy and material science. Presents study deals with the chemical modification of chitosan by using click chemistry technique. The study adopted the approach of clicking azidated chitosan with a synthesized alkyne terminated polymer i.e. poly N isopropylacrylamide with thennoresponsive properties. Structures were confirmed by the FT-IR and HNMR spectra. Thermal characterization was performed showing different thermal behaviour with the chemical modification. The final synthesized graft copolymer can play important role within pharmaceutical formulations carrying drugs for topical or oral treatments.Scientific and Technological Research Council of Turkey (TUBITAK) - Marie Curie Actions under FP7 [115C078]One author (C.Y) acknowledges the financial support from "The Scientific and Technological Research Council of Turkey (TUBITAK), CoFunded by Marie Curie Actions under FP7", project number 115C078 and Ege University, Faculty of Pharmacy, Pharmaceutical Sciences Research Centre (FABAL) for some instrumental analysis

Chitosan-Graft-Poly(N-Isopropylacrylamide)/PVA Cryogels as Carriers for Mucosal Delivery of Voriconazole

YILMAZ, ONUR/0000-0002-0992-5937; Kose, Fadime Aydin/0000-0001-5222-7555; Kose, Fatih/0000-0002-0156-5973WOS: 000489104300058PubMed: 31480489The objective of this study was to prepare and characterize physically crosslinked gel formulations of chitosan (CS)-graft-poly(N-isopropyl acrylamide) (PNIPAAm) and polyvinyl alcohol (PVA) for smart delivery of an antifungal drug, Voriconazole, for mucosal applications. For this purpose, cryogels of CS-g-PNIPAAm/PVA and CS/PVA were tested by means of texture profile analysis and rheology to determine optimal matrix properties for topical application. the ratio of 75/25 v/v % CS-g-PNIPAAm/PVA was selected to be used for formulation since it gave low compressibility and hardness (1.2 and 0.6 N) as well as high adhesion properties and non-Newtonian flow behavior. the cryogels and formulations were further characterized by means of FTIR spectroscopy, swelling behavior, texture analysis, scanning electron microscopy (SEM), thermal (differential scanning calorimetry (DSC) and TGA), and rheological behavior. the drug loading capacity and in vitro release profile of the drug, storage stability, and cytotoxicity tests were also performed for the gel formulation. the FTIR, DSC, and TGA results verified the successful formation of cryogels. Swelling studies revealed a pH-dependent swelling ability with a maximum swelling degree of 1200% in acid and 990% in phosphate buffer (pH = 7.4). Thermal studies showed that CS-g-PNIPAAm/PVA 75/25 had higher thermal stability proving the structural complexity of the polymer. the loading capacity of Voriconazole was found to be 70% (w/w). the in vitro release profiles of Voriconazole showed Fickian release behavior for CS-g-PNIPAAm/PVA 75/25 gel with an approximate delivery of 38% within 8 h, slower than matrices containing unmodified chitosan. the storage stability test exhibited that the gel formulation was still stable even after aging for two months. Moreover, the cell culture assays revealed a non-toxic character of the polymeric matrix. Overall results showed that the CS-g-PNIPAAm/PVA 75/25 hydrogel has the potential to be used as a smart polymeric vehicle for topical applications.Scientific and Technological Research Council of Turkey (TUBITAK) - Marie Curie Actions under FP7" [115C078]C.N.C.-Y. acknowledges the financial support from "The Scientific and Technological Research Council of Turkey (TUBITAK), Co-Funded by Marie Curie Actions under FP7", project number 115C078

Halogen-Free Waterborne Polymeric Hybrid Coatings for Improved Fire Retardancy of Textiles

Wildfires are becoming more intense and more frequent, ravaging the habitations and ecosystems in their path. One solution to reducing the risk of damage to buildings and other structures during a fire event is the use of fire-retardant coatings that can stop or slow down the spread of flames, especially for textile materials. The present study focuses on the preparation and application of halogen-free boron/bentonite-based polymeric fire-retardant (FR) hybrid coating formulations for fabrics such as cotton (CO) and polyester (PE) fibers. For the preparation of FR composites, two types of boron derivatives, disodium octaborate and zinc borate, were used in combination with sodium bentonite. A styrene-acrylic copolymer was specifically synthesized and used as a coating binder for FR components to apply on fabrics. The properties of the synthesized copolymer and FR composites were characterized with a particle size analysis, FTIR spectroscopy, a dynamic mechanical thermal analysis (DMTA), and rheological measurements. The obtained hybrid composites based on styrene-acrylic copolymers and two different inorganic fillers were applied on cotton (CO) and polyester (PE) fabrics with a screen-printing technique, and the flame retardancy performance of the finished textile samples was investigated by means of flame spread and limit oxygen index (LOI) tests. The findings showed that the FR-composite-coated fabrics had higher LOI values and much decreased flame spread rates in comparison with uncoated ones. Among the boron derivatives, the composites prepared with disodium octaborate (FR-A) had much more pronounced LOI values and decreased flame spread behavior in comparison with the composite with zinc borate (FR-B). When compared to a commercial product, the FR-A composite, in conjunction with the specially synthesized polymer, demonstrated commendable fire retardancy performance and emerged as a promising candidate for a halogen-free waterborne fire-retardant coating for fabrics

PREPARATION AND CHARACTERIZATION OF ALGINATE AND CHITOSAN IPC BASED GEL FORMULATION FOR MUCOSAL APPLICATION

WOS: 000486383100004Interpolymeric complexes (IPCs) have the advantage of combined properties of their constituent polymers. They are easy to prepare under mild conditions and do not require high processing costs. The interpolymeric complexes of alginate, chitosan and Nystatin, as antifungal drug systems, represent an alternative for mucosal illness treatment. The composition of the two polymers is a key parameter in obtaining the desired properties for pharmaceutical formulations. IPCs of sodium alginate (SA) and chitosan (CS) were prepared via solution mixing method with various compositions, followed by coacervation in 2-propanol. The outcome obtained from rheological measurements was that the complex SA/CS 60/40 (v/v %) fulfilled the requirements of a semi-solid formulation, e.g. pseudoplasticity. Nystatin showed very good compatibility with the polymeric system. The drug loaded gels showed better rheological, textural and mechanical properties (e.g. pseudoelasticity, spreadability, surface adhesion etc.). The final gel formulations showed no cytotoxic effects in the cell culture assay.Scientific and Technological Research Council of Turkey (TUBITAK)Turkiye Bilimsel ve Teknolojik Arastirma Kurumu (TUBITAK); Marie Curie Actions under FP7European Union (EU) [115C078]Cheaburu-Yilmaz C.N. acknowledges the financial support from "The Scientific and Technological Research Council of Turkey (TUBITAK), CoFunded by Marie Curie Actions under FP7", project number 115C078. Additionally, the authors acknowledge Ege University, Faculty of Pharmacy, Pharmaceutical Sciences Research Centre (FABAL) for some instrumental analysis

Development of Vaginal Carriers Based on Chitosan-Grafted-PNIPAAm for Progesterone Administration

Chitosan-based hydrogels possess numerous advantages, such as biocompatibility and non-toxicity, and it is considered a proper material to be used in biomedical and pharmaceutical applications. Vaginal administration of progesterone represents a viable alternative for maintaining pregnancy and reducing the risk of miscarriage and in supporting the corpus luteum during fertilization cycles. This study aimed to develop new formulations for vaginal administration of progesterone (PGT). A previously synthesized responsive chitosan-grafted-poly (N-isopropylacrylamide) (CS-g-PNIPAAm) was formulated in various compositions with polyvinyl alcohol (PVA) as external crosslinking agent to obtain pH- and temperature-dependent hydrogels; the hydrogels had the capacity to withstand shear forces encountered in the vagina due to its mechanism of swelling once in contact with vaginal fluids. Three different hydrogels based on grafted chitosan were analyzed via Fourier-transform infrared spectroscopy (FTIR), swelling tests, in vitro drug release, and bioadhesion properties by TA.XTplus texture analysis. A higher amount of PVA decreased the swelling and the bioadhesion capacities of the hydrogel. All hydrogels showed sensitivity to temperature and pH in terms of swelling and in vitro delivery characteristics. By loading progesterone, the studied hydrogels seemed to possess even higher sensitivity than drug–free matrices. The release profile of the active substance and the bioadhesion characteristics recommended the CS-g-PNIPAAm/PVA 80/20 +PGT (P1) hydrogel as a proper constituent for the vaginal formulation for progesterone administration

Preparation and in vitro evaluation of melatonin-loaded HA/PVA gel formulations

WOS: 000445486600009PubMed ID: 27915492Melatonin-loaded hyaluronic acid (HA) and poly(vinyl alcohol) (PVA) gels were prepared by using freeze-thaw technique and an emulsion method followed by freeze-thaw technique to produce a new synergistic system for topical application. Freeze-thaw hydrogels and emulgels were characterized by means of Fourier transform infrared spectroscopy, rheology and swelling tests. The porous structure of the hydrogels was shown by scanning electron microscopy observations and thermal properties were tested by differential scanning calorimetry measurements. Bioadhesion and in vitro release characterization of formulations were performed by texture profile analysis and dialysis bag method, respectively. The pore size of both formulations was ranging from 900nm to 30m. Melatonin showed a good compatibility with the polymeric matrices as the pores were smaller for the drug-loaded systems. In vitro release studies showed that the release was improved by emulgel formulations. After 24h, the release percentage was found to be 13.240%+/- 1.094 and 15.192%+/- 2.270 for hydrogel and emulgel, respectively. Emulgels had better bioadhesion properties than simple freeze-thaw samples. As a conclusion, regarding the in vitro characterization studies HA and PVA hydrogel and emulgel formulations and their lyophilized forms could be promising systems for topical application of melatonin

Poly(vinyl alcohol)/chitosan/montmorillonite nanocomposites for food packaging applications: Influence of montmorillonite content

WOS: 000389669700003Poly(vinyl alcohol) (PVA)/chitosan (CS)/montmorillonite (C30B) materials for food packaging applications were prepared by using a noninvasive and low-cost freeze/thawing method. Cloisite 30B nanoclay content in PVA/CS gels was varied in order to establish optimum amount to obtain improved properties. The structural, morphological, rheological aspects, thermal stability, and antimicrobial activity were investigated using various techniques as Fourier transform infrared, scanning electron microscopy, rheology, thermogravimetric analysis, differential scanning calorimetry, dynamic mechanical thermal analysis, and antibacterial tests. It was noticed that the obtained materials show an intercalated structure with specific interactions between components and nanoclay incorporation led to an increased thermal stability, mechanical properties, and excellent antimicrobial activity against Escherichia coli, Listeria monocytogenes, and Salmonella typhimurium due to synergistic action of CS and nanoclay.Romanian - EEA Research Programme operated by Ministry of National Education under the European Economic Area Financial Mechanism; Project ACTIBIOSAFE [1SEE/30.06.2014]The research leading to these results has received funding from the Romanian - EEA Research Programme operated by Ministry of National Education under the European Economic Area Financial Mechanism 2009-2014 and Project ACTIBIOSAFE, Contract No 1SEE/30.06.2014