Search

Abstract: Methoxy poly (ethylene glycol) grafted carboxymethyl chitosan (mPEG-g-CMC) and alginate were chosen as the constituents of hydrogel beads for the construction of an interpenetrating polymeric network matrix. A contrast study between the mPEG-g-CMC hydrogel and mPEG physically mixed with CMC hydrogel was carried out. Bovine serum albumin (BSA) as a model for a protein drug was encapsulated in the hydrogel network, and the drug release properties were studied. The hydrogels prepared by these two methods maintained good pH sensitivity; the loading capacity of the mPEG-g-CMC/alginate hydrogel was enhanced in comparison with that of the hydrogel prepared by physically mixing mPEG. The burst release of the protein was slightly decreased at pH 1.2, while the release at pH 7.4 was improved, suggesting that the mPEG-g-CMC/alginate pH-sensitive hydrogel will be promising for site-specific protein drug delivery in the intestine. [Copyright &y& Elsevier]

Abstract: Although the synthetic hydrogel materials capable of accelerating wound healing are being developed at a rapid pace, achieving inorganic–organic hybrid at nanoscale dimension in nanofibrous hydrogels is still a great challenge because of its notorious brittleness and microstructural stability in wet state. Here, we developed a new nanofibrous gelatin/bioactive glass (NF-GEL/BG) composite hydrogel by phase separation method and followed by arming the nanofibers network with counterionic chitosan–hyaluronic acid pairs for improving microstructural and thermal integrity. We achieve this feature by carrying an optimal balance of charges that allows the inorganic ion release in aqueous solution without minimal structure collapse. Therefore, such NF-GEL-based, polysaccharide-crosslinked bioactive hydrogel could afford a close biomimicry to the fibrous nanostructure and constituents of the hierarchically organized natural soft tissues to facilitate chronic, nonhealing wound treatment. [Copyright &y& Elsevier]

Abstract: The need to enhance the immunogenicity of tumor-associated antigens and modulate the resulting immune responses has prompted the development of new adjuvants. We prepared a novel adjuvant, lipopolysaccharides (LPS) loaded thermosensitive hydrogel (LPS-Hydrogel), for truncated basic fibroblast growth factor (tbFGF) peptide to enhance immunological responses and improve therapeutic effects in cancer. When co-formulated with tbFGF, LPS-Hydrogel formed antigen-adjuvant complexes, which enhanced antibody and cell-mediated responses in mice, thus promoting a more balanced antibody-mediated and cytotoxic T lymphocyte (CTL)-mediated immune response to inhibit tumor growth and metastases in vivo. Furthermore, the secretion of IFN-γ and IL-4 was detected, confirming activation of the two immune responses in vivo. There were no significant systemic toxicities observed with tbFGF-LPS-Hydrogel treatment. These results suggested that the thermosensitive and biodegradable LPS-Hydrogel was a novel adjuvant and carrier for peptide vaccines in cancer immunotherapy. [Copyright &y& Elsevier]

Abstract: Sodium alginate (SA) grafted with polyglycidyl methacrylate hydrogels (PGMA-g-SA) was prepared as pH sensitive drug delivery matrices for riboflavin (RF). The hydrogel copolymer matrices were compared with calcium alginate (CA) beads for swelling, degradation, entrapment efficiency and in vitro release of RF. The structure, surface morphology of the CA beads and the prepared hydrogels as well as the chemical stability of the encapsulated drug were characterized by FT-IR and SEM, respectively. The results demonstrate that the optimal formulation was achieved with PGMA-g-SA proportion of (0.75mol/1g) and loaded RF 0.03g. It has been observed that the in vitro release study of RF from this formulation was superior to the other ones and was able to maintain the release for ∼3 and 4 days for the simulated intestinal fluid (SIF) and simulated gastric fluid (SGF), respectively. In general, it has been shown that, GMA grafted onto SA enhanced drug entrapment efficiency, decreased swelling and degradation behaviors of the carrier. In addition, it slowed and controlled the release of RF from the PGMA-g-SA hydrogel compared with pure SA beads crosslinked with Ca2+ ions alone, which thereby provides a facile and effective method to improve the drug delivery systems. [Copyright &y& Elsevier]

Abstract: In the present study the rheological properties of hydrogels obtained through UV irradiation of an aqueous solution of methacrylated inulin (INUMA) alone or in the presence of four different crosslinkers, have been recorded as a function of irradiation time, at two different wavelengths (320 and 365nm) and fixed frequency and amplitude by oscillatory experiments. Each hydrogel has been analyzed by measurements of the frequency-dependency of the elastic modulus, G′, in the linear viscoelastic region. The amount of polymeric chains giving an elastic response has been correlated to the chemical nature of the crosslinker used together with INUMA. Finally the release properties of the hydrogel exhibiting the highest elastic modulus have been tested by using 5-Fluorouracil, as a model drug, and two different loading procedures. The rheological characterization allowed us to determine the most effective condition (appropriate crosslinker, wavelength and irradiation time) to obtain a strong hydrogel that was able to give a modified drug release in simulated gastrointestinal fluids. [Copyright &y& Elsevier]

Abstract: The blends of chitosan (CS) and poly(vinyl alcohol) (PVA) react with tetraethoxy silane (TEOS) to give network structure and their selective crosslinking give hydrogel properties. The swelling properties against different media are changed by varying the amount of PVA in CS/PVA blend. The degree of swelling in water is decreased with increasing amount of PVA. The most significant behavior of these blends is their response against pH, exhibiting low swelling in acidic and basic pH conditions and maximum swelling at neutral pH. This unique behavior along with the biocompatibility of the components made them suitable for oral delivery of enzymes and medicines. Dexamethasone has been selected as a model drug. The released profile of dexamethasone loaded CS/PVA complex showed 9.37% of drug release over a period of 2h in simulated gastric fluid and its transfer to simulated intestinal fluid showed consistent release of remaining drug up to 7h. [Copyright &y& Elsevier]

Abstract: Carbonic anhydrase inhibitors (CAIs) are gaining interest for local treatment of glaucoma and other ocular disorders. The aim of this work was to elucidate the role of cyclodextrins (CDs) in the loading and the release rate of acetazolamide (ACT) and ethoxzolamide (ETOX) from N,N-dimethylacrylamide-co-N-vinylpyrrolidone (DMA-co-NVP) hydrogels, suitable as high water-content soft contact lenses. Two different approaches to incorporate the CDs were evaluated: (i) synthesis of CD monomers and copolymerization with DMA and NVP; and (ii) grafting of natural CDs to preformed hydrogels. Natural β-CD and γ-CD were tested in each approach. The effects of the preparation method on relevant functional features of the hydrogels as well as on cytocompatibility and drug delivery performance were studied in detail. The role played by the CDs strongly depends on the physicochemical properties of the drug and its ability to form complexes; being particularly relevant for slightly soluble molecules that have high affinity for the CDs. Otherwise, unspecific interactions with the network may screen the contribution of the CDs. [Copyright &y& Elsevier]

Abstract: Polymeric matrices of chitosan (CS), 2-hydroxyethyl starch (HES) and their blends prepared by solvent evaporation technique, have been tested as sustained release hydrogels of ropinirole drug. X-Ray diffraction (XRD), infrared spectroscopy (FT-IR) and viscometry measurements showed that the two polymers can form miscible blends. This miscibility is owed to formed hydrogen bonds taking place between the reactive groups of CS and HES and one glass transition is recorded in all blends. Neat polymers were used to prepare solid dispersion formulations with ropinirole drug. It was found that drug was released immediately within 15–30min from HES while the release was slower from CS matrix. Completely different were the release rates from ropinirole with physical mixtures using neat polymers and their blends. Due to the different solubility and swelling behaviour of CS and HES the release rates showed a sustained profile from the blends containing high amounts of CS. [Copyright &y& Elsevier]

Abstract: The aim of the research was to develop a hydrogel tissue expander for orbital implant. To this end, a new superabsorbent hydrogel composed of pectin (PEC) and poly (sodium acrylate) (PAAS) has been fabricated by the free radical copolymerization of acrylic acid (AA) in the pectin aqueous solution. The effects of crosslinker content, initiator content and the weight ratio of PEC to AA on the volume expansion ratios of the PAAS–PEC hydrogels were investigated. In addition, the mechanical properties of the PAAS–PEC hydrogels swollen in PBS were evaluated. Furthermore, the morphologies and structures of the PAAS–PEC hydrogels were characterized by SEM, FTIR and TG. The results revealed that the introduction of pectin contributed to the increase of the volume expansion ratio and the decrease of the mechanical properties for the PAAS–PEC hydrogels. These new PAAS–PEC hydrogels could be promising in orbital implant or other biomedical applications. [Copyright &y& Elsevier]

Abstract: A thermoreversible nanoparticle hydrogels based on carboxylated methoxy poly(ethylene glycol)-grafted chitosan (N-CS-g-mPEG) were investigated in this paper. The aqueous dispersion of N-CS-g-mPEG nanoparticle freeze-dried powder (NP-FDP) can undergo reversible gel–sol transition as the temperature changes. The structures of N-CS-g-mPEG NPs and hydrogels were characterized by TEM, DLS and ESEM. Using 5-Fluorouracil (5-FU), bovine serum albumin (BSA) and dexamethasone (DXM) as model drugs, in vitro release behaviors of drug-loaded hydrogels were also investigated. The release results show that there is a sustained release of BSA and DXM from the drug-loaded hydrogel. In vitro cytotoxicity tests investigated by MTT assay indicate that N-CS-g-mPEG is non-toxic to normal mouse embryonic fibroblast cells (3T3). Therefore, the thermoreversible N-CS-g-mPEG NP hydrogels could be potentially applied in a local minimally invasive drug delivery system. [Copyright &y& Elsevier]

Abstract: CS-αβ-GP thermosensitive hydrogel was prepared with chitosan and αβ-GP which could be transited into gel at 37°C within 10min. The hemolysis rate of blank CS-αβ-GP gel and CS-αβ-GP gel loaded with ADR was 1.37% and 1.32%, respectively. The injected CS-αβ-GP gel did not produce any significant changes in the haematology of SD rats such as white blood cell, red blood cell, platelet and the volume of haemoglobin. In addition, the levels of serum alanine aminotransferase, blood ureic nitrogen and creatinine had no obvious changes in SD rats of different groups. So the CS-αβ-GP hydrogel had good blood compatibility and had no hepatotoxicity or renal toxicity to SD rats. Furthermore, CS-αβ-GP hydrogel had good tissue compatibility according to the inflammatory reaction in SD rats. CS-αβ-GP thermosensitive hydrogel was a promising delivery system which might be used as a long-acting drug delivery vehicle. [ABSTRACT FROM AUTHOR]

Abstract: A series of hydrogels were fabricated from an aqueous solution of gelatin and carboxymethyl chitosan (CM-chitosan) by radiation-induced-crosslinking at ambient temperature. Several physicochemical and biological properties of the hydrogels were investigated to evaluate their potential as wound healing materials. By increasing the CM-chitosan content in the hybrid hydrogels, their swelling ability increased significantly, while the compressive modulus decreased. The miscibility between gelatin and CM-chitosan molecules led to a semi-interpenetrate network after crosslinking. Observed by SEM, scaffolds with a homogeneous interconnected pore structure were obtained after lyophilizing the hydrogels. The enzyme degradation rate of the hydrogels was controlled by adjusting the procedure, which could be matched to the healing rate of the wound. Furthermore, the gelatin/CM-chitosan hydrogels promoted cell attachment and rapid growth of fibroblasts on the material. Due to the high water absorption capacity, a similar compressive modulus with soft tissue, controllable biodegradation, and excellent biocompatibility, the gelatin/CM-chitosan hybrid hydrogels have potential as skin scaffolds and wound healing materials. [Copyright &y& Elsevier]

Abstract: We evaluated the biocompatibility of an injectable chitosan-based thermosensitive hydrogel, which was prepared from chitosan and quaternized chitosan (HTCC) containing α,β-GP (CS-HTCC/GP). The ability of the CS-HTCC/GP thermosensitive hydrogel to partake in periodontal tissue regeneration was investigated. The CS-HTCC/GP thermosensitive hydrogel was found to have no toxic effects and could promote alkaline phosphatase (ALP) activity in human periodontal ligament cells (HPDLCs) in vitro. An extract of the CS-HTCC/GP thermosensitive hydrogel had no obvious influence on the ultrastructure of HPDLCs. The CS-HTCC/GP solution was injected into the rumps of rats resulting in a non-specific inflammation reaction. CS-HTCC/GP thermosensitive hydrogel loading with basic fibroblast growth factor (CS-HTCC/GP-bFGF) more effectively enhanced new periodontal support tissues in dogs. All results indicated that the CS-HTCC/GP thermosensitive hydrogel exhibited excellent biocompatibility and had potential as an injectable local drug delivery vehicle and tissue-engineering scaffold for periodontal disease therapy. [Copyright &y& Elsevier]

Abstract: The swelling kinetics of a series of carboxymethylchitosan-g-poly(acrylic acid) hydrogels pretreated under acidic buffer media has been studied. Sigmoidal swelling curves are exhibited when these pretreated hydrogels are subsequently immersed in the buffer solutions of pH 6.0–7.4. This phenomenon may be attributed to the disruption of a cooperative physical cross-linking (i.e. the hydrogen bonding and the ionic cross-linking) on the networks, which was proved by the change of FT-IR spectra of hydrogels during swelling. The buffer pH, the pretreating pH and the composition of hydrogels have an obvious influence on the sigmoidal effect. The profile of drug release at pH 7.0 from the hydrogel which was prepared in the pH 2.2 buffer containing 5-aminosalicylic acid (5-ASA) exhibits a sigmoidal release curve, namely, an initial slow release followed by a burst release. The swelling kinetics shows the potential in the design of the colon-specific drug delivery system. [ABSTRACT FROM AUTHOR]

Abstract: This work was intended to develop a new cross-linked gelatinized starch–xanthan gum hydrogel system, to characterize the properties of the new material, and to explore its potential applications in controlled drug delivery. Cross-linked starch–xanthan gum polymers were synthesized with varying levels of xanthan gum and sodium trimetaphosphate (STMP). The reaction of starch–xanthan gum polymers with STMP was examined using solid 31P NMR spectroscopy and FTIR. Morphology of the films made from the new polymers was studied by scanning electron microscopy. The swelling properties and the network parameters such as gel mesh size of the films were investigated. The permeation of solutes with various molecular weights and charges across the films was determined. 31P NMR and FTIR spectra showed that both starch and xanthan gum were reacted with STMP. The swelling ratio of the films was higher at higher STMP and xanthan gum levels. The gel mesh size increased with increasing swelling ratio varying from 2.84 to 6.74nm. Permeability of anionic drugs across the polymeric films was significantly lower than their neutral form due mainly to the electrostatic repulsion between the negatively charged drugs and the polymer. The results suggest that the new cross-linked starch–xanthan gum hydrogels can be potentially used as a film-forming material in controlled release formulations. [Copyright &y& Elsevier]

Abstract: The objective of this study was to prepare and cross-link carrageenan beads that may be used as a controlled release delivery system. The influence of the bulk carrageenan and cross-linker concentrations on the bead size was studied in order to assess the mechanism of cross-linking between epichlorohydrin and the polysaccharide. The conditions were optimised on macroparticles (3.1mm in diameter) for a better understanding of the cross-link density and its effect on the morphology and surface topography of the bead. It was shown that low epichlorohydrin concentrations led to unstable and weak beads with uneven and cracked surfaces. The optimum cross-linker concentration, which resulted in smooth and stable gel beads, was applied to microparticles (76μm in diameter). The swelling/shrinking behaviour of these cross-linked microgels in saline solutions showed great potential for the application of these micro-sponges as delivery systems in food or pharmaceutical products. [Copyright &y& Elsevier]

Abstract: The aim of this study was to examine the antimicrobial efficiency and color changes of cotton fabrics loaded with colloidal silver nanoparticles which were synthesized without using any stabilizer. The influence of colloidal concentration and consequently, the amount of silver deposited onto the fabric surface, on antimicrobial activity against Gram-negative bacterium Escherichia coli, Gram-positive bacterium Staphylococcus aureus and fungus Candida albicans as well as laundering durability of obtained effects were studied. Although cotton fabrics loaded with silver nanoparticles from 10ppm colloid exhibited good antimicrobial efficiency, their poor laundering durability indicated that higher concentrated colloids (50ppm) must be applied for obtaining long-term durability. Additionally, the influence of dyeing with C.I. Direct Red 81 on antimicrobial activity of cotton fabrics loaded with silver nanoparticles as well as the influence of their presence on the color change of dyed fabrics were evaluated. Unlike color change, the antimicrobial efficiency was not affected by the order of dyeing and loading of silver nanoparticles. [Copyright &y& Elsevier]

Abstract: The water swellable hydrogels are commonly used in the production of solid pharmaceutical dosage systems for oral administration (matrices). Their use allows to obtain the controlled drug release. The key role is played by the transport phenomena which take place: water up-take, gel swelling and erosion, increase in diffusivity due to hydration. Thus, knowledge of these phenomena is fundamental in designing and realizing the pharmaceutical systems. In this work, tablets made of pure hydrogel, HydroxyPropyl-MethylCellulose (HPMC), were produced and immersed in a thermostatic bath filled with stirred distilled water (37°C). The water up-take was allowed only by radial direction (from the lateral surface) by confining the tablet between two glass slides. Two distinct methods, an optical technique already described in a previous work, and a gravimetric procedure described here, were applied to measure the water concentration profiles along the radial direction in the tablets. The data obtained were used both to clarify the nature of the transport phenomena involved, and to perform a better tuning of a mathematical model previously proposed. [Copyright &y& Elsevier]

Abstract: This paper is aimed to the macro- and microscopic characterisation of a scleroglucan–borax gel system eventually hosting model drugs. A rheological study was carried out, also as a function of temperature, on samples at different polymer concentrations in the presence and without guest model drug. Applying the generalised Maxwell model the mechanical spectra, showing the gel-like characteristics dependent on polymer concentration, were obtained. Flory’s theory and the equivalent network approach were applied to the rheological data in order to describe the molecular arrangement of the scleroglucan chains in the presence of borate ions with an estimation of the network mesh size, ξ. Diffusion experiments of three model drugs, with different van der Waals radius, allowed the determination of the diffusion coefficients. An evaluation of the network mesh size was also obtained by means of a modified free volume theory and a good agreement between the two sets of ξ values was found. [Copyright &y& Elsevier]

Abstract: In this paper, we reported the synthesis and properties of interpenetrating polymer network (IPN) hydrogel systems designed for colon targeted drug delivery. The gels were composed of konjac glucomannan (KGM) and cross-linked poly(acrylic acid) (PAA) by N,N-methylene-bis-(acrylamide) (MBAAm). It was possible to modulate the swelling degree of the gels. And the swelling ratio has sensitive respondence to the environmental pH value variation. The degradation tests show that the hydrogels retain the enzymatic degradation character of KGM. In vitro release of model drug VB12 was studied in the presence of Cellulase E0240 in pH 7.4 phosphate buffer at 37°C. The accumulative release percent of the model drug reached 85.6% after 48h and the drug release was controlled by the swelling and the degradation of the hydrogels. The results indicated that the IPN hydrogels can be exploited as potential carriers for colon-specific drug delivery. [Copyright &y& Elsevier]

Abstract: In this investigation, the fabrication, physico-chemical and biological characterization of a novel smart hydrogel had been evaluated for its potentials in effective controlling protein delivery. The hydrophilic pachyman-based hydrogel was generated facilely by crosslinking hydrosoluble carboxymethyl pachyman (CMP) with epichlorohydrin (ECH). The ECH concentration possessing maximum (99.7%) encapsulation efficiency and the most appropriate swelling characteristics was found to be 1.25% (w/v). The resultant hydrogel exhibited swelling ratios most favorable for drug release in simulated intestinal media. It could release two model protein drugs (bovine serum albumin and lysozyme) in the controlled manner and with full preservation of the protein stability and enzymatic activity. Importantly, the ECH-CMP hydrogel was confirmed to be biocompatible and biodegradable. From these findings, we were able to conclude that the synthesized pachyman-based hydrogel would be a promising delivery carrier candidate for site-specific delivery of protein drugs. [Copyright &y& Elsevier]

Abstract: Natural polymers are considered high value polymeric materials because of their potential as biocompatible materials with medical applications. The chemical modification of natural polymers by grafting has received considerable attention in recent years because of the wide variety of monomers available. As the first part of a continued research on conversion of carboxymethyl starch (CMS) to useful biopolymer-based materials, large numbers of carboxylic functional groups were introduced onto CMS by grafting with polymethacrylic acid (PMAA). Free radical graft copolymerization was carried out at 70°C, bis-acrylamide as a crosslinking agent and persulfate as an initiator. Equilibrium swelling studies were carried out in enzyme-free simulated gastric and intestinal fluids (SGF and SIF, respectively). Also, the sodium dicofenac as a model drug was entrapped in these nano-gels and the in vitro release profiles were established separately in both enzyme-free SGF and SIF. The drug release was found to be faster in SIF. The drug-release profiles indicate that amount drug release depends on their degree of swelling, and crosslinking. This hydrogel converted to nano by freeze-drying method and characterized by scanning electron microscopy, differential scanning calorimetry and FT-IR spectrometry. [Copyright &y& Elsevier]

Abstract: Acryloyl guar gum (AGG) and its hydrogel materials were synthesized for use as carriers and slow release devices of two pro-drugs, l-tyrosine and 3,4-dihydroxy phenylalanine (l-DOPA). To evaluate their structure-properties relationship, these were characterized by scanning electron micrography (SEM), FTIR spectroscopy and swelling studies. The hydrogel materials responded to the change of pH of the swelling medium, and exhibited reversible transitions in 0.9% saline solution. These were loaded with two pro-drugs, and their cumulative release behavior was studied at pH 2.2 and pH 7.4. The hydrogel materials exhibited structure-property relationship in the release of these pro-drugs. The % cumulative release of l-tyrosine was the maximum from the AGG-g-poly(methacrylic acid), while the maximum release of l-DOPA was observed from AGG-g-poly(AAc) in both the media. On the other hand, the AGG-g-poly(2-hydroxyethyl methacrylate) and AGG-g-poly(2-hydroxypropyl methacrylate) retained 42.33% and 49.05% of the drug even after 12h. [Copyright &y& Elsevier]