Self-aggregated nanoparticles from methoxy poly(ethylene glycol)-modified chitosan: synthesis; characterization; aggregation and methotrexate release in vitro

Methoxy poly(ethylene glycol)-grafted-chitosan (mPEG-g-CS) conjugates were synthesized by formaldehyde linking method and characterized by Fourier transform infrared (FT-IR) and proton nuclear magnetic resonance (¹H-NMR). The degree of substitution (DS) of methoxy poly (ethylene glycol) (mPEG) in the mPEG-g-CS molecules determined by ¹H-NMR ranged from 19% to 42%. The critical aggregation concentration (CAC) was determined by fluorescence spectroscopy using pyrene as fluorescence probe and its value was 0.07 mg/mL in water. mPEG-g-CS formed monodisperse self-aggregated nanoparticles with a roughly spherical shape and a mean diameter of 261.9 nm were prepared by the dialysis method. mPEG-g-CS self-aggregated nanoparticles were used as carriers of poorly water-soluble anticancer drug methotrexate (MTX). MTX was physically entrapped inside mPEG-g-CS self-aggregated nanoparticles by dialysis method and the characteristics of MTX-loaded mPEG-g-CS self-aggregated nanoparticles were analyzed using dynamic laser light scattering (DLLS), transmission electron microscopy (TEM). Moreover, in vitro release behavior of MTX was also investigated and the results showed that MTX was continuously released more than 50% in 48 h.     

pH and ionic sensitive chitosan/carboxymethyl chitosan IPN complex films for the controlled release of coenzyme A

pH and ionic sensitive interpenetrating polymer network (IPN) complex films based on chitosan (CS) and carboxymethyl chitosan (CM-CS) were prepared by using glutaraldehyde as crosslinking agent. Its structure was characterized by FT-IR, which indicated that the IPN was formed. The films were studied by swelling, weight loss with time, and release of coenzyme A (CoA). It was found that the IPN films were sensitive to pH and ionic strength of the medium. The cumulative release rate of CoA decreased with CoA loading content, ionic strength or crosslinking agent increasing. The composition of the IPN films and pH of release medium also had significant effect on the release of CoA. The differences in the rates and amounts of released CoA may be attributed to the swelling behavior, the degradation of films, and interaction between drug molecule and polymer matrix. These results suggested CS/CM-CS IPN films could be used as drug delivery carrier.     

Construction of a pH-responsive drug delivery platform based on the hybrid of mesoporous silica and chitosan

Mesoporous silica nanoparticles (MSN) have been widely used for drug delivery due to their large specific surface area and excellent biocompatibility. However, the mesoporous structure of MSN would lead to the inevitable “premature release” of the drugs, and therefore the modification of MSN for controlled delivery seems to be a necessary step. Herein, chitosan (CS) was used for the surface functionalization of MSN via amidation reaction, and the introduced CS could function as a “gatekeeper” and the drug of methotrexate (MTX) might be encapsulated in the mesopores of MSN. As a result, the “premature release” of the encapsulated MTX could be effectively circumvented with the aid of the CS cap. More importantly, the drug delivery from the hybrid of MSN and CS (MSN/CS) can be endowed with pH-sensitivity by the introduction of CS because the amide bonding between CS and MSN is highly pH-sensitive. The cumulative release of MTX from the MSN/CS is more pronounced at pH 5.0 (80.86%) than those at pH 6.8 (40.46%) and pH 7.4 (18.25%).     

Preparation and characterization of temperature and pH-sensitive chitosan material and its controlled release on coenzyme A

A novel copolymer P(CS–Ma–DMAEMA) was synthesized with chitosan (CS), maleic anhydride (Ma) and 2-(dimethylamino)ethyl methacrylate (DMAEMA) by grafting and copolymerization. The copolymer obtained was analyzed by FT-IR, ¹H NMR and UV, and the molecular weight and polydispersity were determined by gel permeation chromatography (GPC). The average size and distribution of copolymer micelles were determined by dynamic light scattering (DLS). Their aqueous solution properties and controlled coenzyme A delivery were also studied. It was found that the copolymer had temperature sensitivity and pH sensitivity. The factors affecting release behavior, such as concentration, pH and temperature were discussed in this paper. The higher concentration of the copolymer aqueous solution absorbed more coenzyme A than the lower one. The increasing temperature accelerated the drug release from the copolymer. The pH of the copolymer solution had significant impact on the release of coenzyme A. The results suggested that the novel copolymer could be used as drug delivery carrier.     

Self-aggregated nanoparticles of cholesterol-modified chitosan conjugate as a novel carrier of epirubicin

Cholesterol-modified chitosan conjugate with succinyl linkages (CHCS) was synthesized and characterized by fourier transform infrared (FTIR) and proton nuclear magnetic resonance (¹H NMR). The degree of substitution (DS) of cholesterol moiety determined by elemental analysis was 7.3%. The self-aggregation behavior of CHCS was evaluated by the fluorescence probe technique and the critical aggregation concentration (CAC) was 1.16 × 10⁻² mg mL⁻¹ in 0.1 M acetic acid solution. CHCS formed monodisperse self-aggregated nanoparticles with a roughly spherical shape and a mean diameter of 417.2 nm by probe sonication in aqueous media. Epirubicin (EPB), as a model anticancer drug, was physically entrapped inside CHCS self-aggregated nanoparticles by the remote loading method and the characteristics of EPB-loaded CHCS self-aggregated nanoparticles were analyzed using dynamic laser light scattering (DLLS), transmission electron microscopy (TEM) and fluorescence spectroscopy. EPB-loaded CHCS self-aggregated nanoparticles were almost spherical in shape and their size increased from 338.2 to 472.9 nm with the EPB-loading content increasing from 7.97% to 14.0%. The release behavior of EPB from CHCS self-aggregated nanoparticles was studied in vitro by dialysis method. The results showed that EPB release rate decreased with the pH increase of the release media. In phosphate buffered saline (PBS, pH 7.4), the EPB release was very slow and the total release amount was about 24.9% in 48 h.     

Analytical characterization of chitosan nanoparticles for peptide drug delivery applications

Chitosan-cyclodextrin hybrid nanoparticles (NPs) were obtained by the ionic gelation process in the presence of glutathione (GSH), chosen as a model drug. NPs were characterized by means of transmission electron microscopy and zeta-potential measurements. Furthermore, a detailed X-ray photoelectron spectroscopy study was carried out in both conventional and depth-profile modes. The combination of controlled ion-erosion experiments and a scrupulous curve-fitting approach allowed for the first time the quantitative study of the GSH in-depth distribution in the NPs. NPs were proven to efficiently encapsulate GSH in their inner cores, thus showing promising perspectives as drug carriers.     

Characterization of scaffolds based on chitosan and collagen with glycosaminoglycans

Scaffolds based on chitosan (CTS), collagen (Coll), and glycosaminoglycans (GAGs) cross-linked by N-(3-dimethylamino propyl)-N′-ethylcarbodiimide hydrochloride (EDC) and N-hydroxysuccinimide (NHS) mixture were obtained with the use of the freeze-drying method. They were characterized by different analyses, e.g. mechanical and swelling tests, porosity, and density measurement. Moreover, the scaffolds behavior in cell culture was examined with human osteosarcoma SaOS-2 cells. The results showed that the scaffolds based on CTS, Coll, and GAGs cross-linked by EDC/NHS present physicochemical properties appropriate for biomedical purposes. They show porosity above 90% and are highly swellable. The increasing GAGs content improves the attachment and survival of cells on the obtained scaffolds. It can be assumed that scaffolds based on CTS and Coll, GAGs-enriched and cross-linked by EDC/NHS addition are biocompatible, and have properties appropriate for the tissue engineering purposes.     

Novel nanoparticles composed of chitosan and β-cyclodextrin derivatives as potential insoluble drug carrier

This research was aim to develop novel cyclodextrin/chitosan(CD/CS) nanocarriers for insoluble drug delivery through the mild ionic gelation method previously developed by our lab. A series of different bcyclodextrin(β-CD) derivatives were incorporated into CS nanoparticles including hydroxypropyl-bcyclodextrin(HP-β-CD), sulphobutylether-β-cyclodextrin(SB-β-CD), and 2,6-di-O-methy-β-cyclodextrin(DM-β-CD). Various process parameters for nanoparticle preparation and their effects on physicochemical properties of CD/CS nanoparticles were investigated, such as the type of CD derivatives,CD and CS concentrations, the mass ratio of CS to TPP(CS/TPP), and p H values. In the optimal condition,CD/CS nanoparticles were obtained in the size range of 215–276 nm and with the zeta potential from30.22 m V to 35.79 m V. Moreover, the stability study showed that the incorporation of CD rendered the CD/CS nanocarriers more stable than CS nanoparticles in PBS buffer at p H 6.8. For their easy preparation and adjustable parameters in nanoparticle formation as well as the diversified hydrophobic core of CD derivatives, the novel CD/CS nanoparticles developed herein might represent an interesting and versatile drug delivery platform for a variety of poorly water-soluble drugs with different physicochemical properties.     

Synthesis and Characterization of Chitosan-Albumin Conjugates as pH-Sensitive Biodegradable Hydrogels

A new kind of biodegradable pH-sensitive drug delivery system was developed via chitosan-albumin conjugate hydrogel. Through changing the feeding modes of reactants, two types of hydrogels(comb-type and reticular-type) were synthesized by amidation reactions between 6-O-succinoylated N-phthaloyl chitosan and albumin. The structures and morphologies of the hydrogels were characterized by SEM. And their water swelling capacity, drug loading and releasing properties at different pH values were also investigate...     

A preliminary study on fabrication of nanoscale fibrous chitosan membranes in situ by biospecific degradation

A new approach for in situ fabrication of nanoscale fibrous chitosan membrane by biospecific degradation under physiological situation was studied. The chitosan binary blend membranes were fabricated by solvent casting of chitosan solution containing highly deacetylated chitosan (HDC) and moderately deacetylated chitosan (MDC) with different ratio. The biodegradation process was performed in PBS (pH 7.4) containing lysozyme at the temperature of 37 °C. Experimental results from weight loss, reducing sugar in surrounding media, FT-IR, X-ray diffraction, gel permeation chromatography (GPC) and SEM throughout the study showed that the biospecific degradation by lysozyme had removed MDC component selectively. When the ratio of MDC in the binary blend membranes amounted to 0.5, nanoscale domains of HDC and MDC were obtained, and thus a nanoscale fibrous structure was fabricated after biospecific degradation of MDC. This nanofibrous structure and the biospecific degradation of chitosan membranes can have potential advantages and interesting implications in tissue engineering and drug delivery.     

Preparation of chitosan scaffolds loaded with dexamethasone for tissue engineering applications using supercritical fluid technology

Supercritical fluid impregnation was tested to prepare a new scaffold loaded with a bioactive compound. Dexamethasone is used in osteogenic media to direct the differentiation of stem cells towards the osteogenic lineage. Dexamethasone was impregnated in chitosan scaffolds at different operating conditions, in order to optimize the impregnation process. Pressure and temperature affect the carbon dioxide density and influence the swelling of the polymer and the drug solubility in the fluid phase, therefore these are two important parameters that were studied in this work. Chitosan sponges prepared by freeze drying were impregnated with the active compound at pressures from 8.0 up to 14.0 MPa and temperatures from 35 up to 55 °C. The effect of the impregnation contact time (3 h and 6 h) was also evaluated. From the experiments performed we can conclude that the yield of impregnation is lower when increasing pressure and temperature. The contact time will mainly influence the amount of drug impregnated in the scaffold and for higher contact times the impregnation yield is also higher. Scanning electron microscopy shows particles of dexamethasone in the bulk of the scaffold, which confirms the feasibility of the supercritical fluid impregnation technology for the preparation of delivery devices. The loading capacity of the scaffolds was determined by spectroscopic analysis and the highest loading was achieved for the experiments performed at 8.0 MPa and 35 °C. Furthermore, in vitro drug release studies were carried out and the results show that dexamethasone was sustainably released. Supercritical fluid impregnation proved to be feasible for the preparation of a drug delivery system for bone tissue engineering purposes.     

Characterization and biocompatibility of chitosan nanocomposites

Chitosan nanocomposites were prepared from chitosan and gold nanoparticles (AuNPs) or silver nanoparticles (AgNPs) of ～5 nm size. Transmission electron microscopy (TEM) showed the NPs in chitosan did not aggregate until higher concentrations (120-240 ppm). Atomic force microscopy (AFM) demonstrated that the nanocrystalline domains on chitosan surface were more evident upon addition of AuNPs (60 ppm) or AgNPs (120 ppm). Both nanocomposites showed greater elastic modulus, higher glass transition temperature (T(g)) and better cell proliferation than the pristine chitosan. Additionally, chitosan-Ag nanocomposites had antibacterial ability against Staphylococcus aureus. The potential of chitosan-Au nanocomposites as hemostatic wound dressings was evaluated in animal (rat) studies. Chitosan-Au was found to promote the repair of skin wound and hemostasis of severed hepatic portal vein. This study indicated that a small amount of NPs could induce significant changes in the physicochemical properties of chitosan, which may increase its biocompatibility and potential in wound management.     

微乳液法制备可共载水溶和脂溶药物的壳聚糖季铵盐乙醇脂质体的载药性能表征

采用微乳液法制备了可包载脂溶性和水溶性药物的羧甲基壳聚糖十八烷基季铵盐(OQCMC)乙醇脂质体,研究了OQCMC乙醇高分子脂质体的相图、粒径和电位、对药物的包封及释放能力及共载水溶性和脂溶性荧光染料后的细胞内递送能力.结果表明:OQCMC上长链季铵盐分子的取代度和共乳化剂乙醇的加入量对相图中微乳区域的面积影响不大;微乳液法可制备包载水溶性长春新碱(VCR)、脂溶性消炎痛(IMC)或二者共载的OQCMC载药微球,微球粒径为(52.40±0.55)nm,分布均匀;微乳液体系对VCR的最大载药率为22.7%,对IMC的最大载药率为20.1%,二者共载时,VCR的最大载药率为12.2%,IMC的最大载药率为10.0%;载药微球对药物具有缓控释功能.OQCMC乙醇高聚物脂质体可有效地包载荧光染料异硫氰酸荧光素FITC(水溶性)和尼罗红(脂溶性),并将二者递送到卵巢癌HO8901细胞内.     

Chitosan nanoparticles crosslinked by glycidoxypropyltrimethoxysilane for pH triggered release of protein

pH-responsive-chitosan nanoparticles for the control release of protein drug were prepared by combining two-step crosslinking method,in which chitosan was subsequently crosslinked by sodium tripolyphosphate(TPP)and glycidoxypropyltrimethoxysilane (GPTMS).Compared with TPP crosslinked chitosan particles,the two-step crosslinked nanoparticles were not only pH-responsive but also more stable in wide pH range.Fluorescein isothiocyanate(FITC)labeled anti-human-IgG antibody was used as a model protein drug for...     

新型介孔羟基磷灰石/壳聚糖-万古霉素药物释放系统复合材料的制备及体外抗菌和成骨能力

采用冷冻干燥法合成了介孔羟基磷灰石(HA)/壳聚糖(CS)-万古霉素(VCM)药物释放系统复合材料, 利用SEM, XRD和FTIR等方法对材料进行了表征. 结果证实CS与HA混合复合材料具有良好的孔径和孔隙率, 万古霉素吸附于复合材料的表面和内部. 细胞毒性实验[噻唑蓝(MTT)比色法]结果表明, 材料可以促进成骨细胞增殖且具有良好的细胞相容性. 体外抑菌实验结果证实此材料可长时间抑制耐甲氧西林金葡菌(MRSA)的生长, 具有良好的抑菌和杀菌能力. 细胞黏附实验结果表明, 成骨细胞附着于材料表面增殖并通过孔道延伸. 实时聚合酶链式反应(RT-PCR)实验结果表明, 在成骨相关标志产物胶原蛋白-1(COL-1)及骨形态发生蛋白-2(BMP-2)基因上均有较高的表达, 表明材料在体外可以促进成骨细胞生长, 具有良好的成骨能力.     

Films based on chitosan polyelectrolyte complexes for skin drug delivery: Development and characterization

Novel chitosan based polyelectrolyte complexes (PEC) were developed and optimized in order to obtain films possessing the optimal functional properties (flexibility, resistance, water vapour transmission rate and bioadhesion) to be applied on skin. The development was based on the combination of chitosan and two polyacrylic acid (PAA) polymers with different crosslinkers and crosslinking densities. The interaction between the polymers was maximized controlling the pH, and by forming the films at a pH value close to the pK_a of the respective components as identified by potentiometric and turbidimetric titrations. The action of glycerol, PEG200, Hydrovance and trehalose upon the functional properties of the films was also evaluated. Glycerol was found to improve the film properties in terms of flexibility, resistance and water vapour transmission rate (WVTR) with a maximum effect at 30%. The application of a pressure sensitive adhesive (PSA) significantly improved bioadhesion with a negligible influence in the resistance and flexibility of the films.The optimized film, including adhesive, has shown very good properties for application in the skin and represents a very promising formulation for further incorporation of drugs for topical and transdermal administration.     

Therapeutic effects of the as-synthesized polylactic acid/chitosan nanofibers decorated with amphotricin B for in vitro treatment of Leishmaniasis

Leishmaniasis is one of the biggest concerns of the World Health Organization (WHO) due to its severe side effects, the emergence of resistance, and secondary bacterial infections; therefore, it was reported as an epidemic, especially in immunocompromised individuals. The main purpose of this study was to synthesize and characterize the polylactic acid (PLA)/chitosan nanofibers decorated with amphotericin B as a new delivery system for the in vitro treatment of leishmaniasis wounds. The prepared nanofibers were characterized using scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), dynamic light scattering (DLS), X-ray diffraction (XRD), and in vitro drug release test. The anti-leishmanial effect of nanofibers decorated with amphotericin B against Leishmania major promastigotes and its cytotoxicity to macrophages were determined by the flow cytometry test. The in vitro drug release assay indicated that 84% of the amphotericin B loaded in nanofibers was released after 400 min. The average concentration of the amphotericin B loaded in PLA/chitosan nanofibers and the conventional form of amphotericin B that prevented the growth of 50% of the promastigotes of L. major were 1.29 and 4.34 µg/mL, respectively.     

The kinetics of adsorption of tetracycline on chitosan particles

Experiments to monitor and characterize the kinetics of adsorption of tetracycline on chitosan particles are reported in this work. The same pseudo-order kinetics that has been widely used for describing the adsorption in systems related to wastewater purification and drug loading was used to treat the present data. As some unexpected results came out from the experiments, it was necessary a detailed deduction for this sort of kinetics to be carried out, so that approximations related to short and long times were obtained. Firstly it was shown that an apparently linear t/q(t) versus t relationship did not imply a pseudo-second-order sorption kinetics, differently of what has been repeatedly reported in the literature. It was found that this misinterpretation could be avoided by using non-linear regression. Finally, the adsorption of tetracycline on chitosan particles was analyzed, using the insights obtained from theoretical analysis, and the parameters generated were used to analyze to adsorption kinetics and to propose an adsorption mechanism.     

In vitro degradation and release profiles for electrospun polymeric fibers containing paracetanol

In the paper, the poly(D,L-lactide) (PDLLA) and poly(ethylene glycol)-co-poly(D,L-lactide) (PELA) fibers with and without paracetanol drug loading were prepared with an electrospinning method. The morphology of the fibers was observed by scanning electronic microscope (SEM). Their glass transition temperatures (T(g)) were measured with differential scanning calorimetry (DSC). The water contact angle (CA) measurement was also performed to characterize surface properties of fibers. At 37 degrees C in a PBS buffer solution (pH 7.4), in vitro matrix degradation profiles of these fibers were characterized by measuring their weight loss, the molecular weight decrease, and their morphology change. The result showed that the effects of fiber diameter and porosities on the degradation of the electrospun scaffolds might exceed the effects of the molecular weight and the PEG contents, which was different from the polymeric microspheres degradation. In vitro paracetanol release profiles were also investigated in the same condition. The result showed that the drug burst release behaviour was mainly related with the drug-polymer compatibility and the followed sustained release phase depended on polymer degradation.     

Fabrication of polyvinyl alcohol/chitosan oligosaccharide hydrogel: physicochemical characterizations and in vitro drug release study

Abstract

Hydrogel composites from polyvinyl alcohol and chitosan have been developed by various researchers as a function of their composition for various medical applications. Although, the solubility of chitosan in acidic solvents may limit its wide bioengineering applications. In this article, we demonstrate that polyvinyl alcohol-chitosan oligosaccharide (water soluble) to develop cross-linked hydrogel network using chemical cross linker. X ray diffraction, Fourier transform infrared spectroscopy, and wettability study of these hydrogels were also performed. Lomefloxacin drug was loaded into the hydrogels and its release profile was studied.