pH responsive cross-linked polymeric matrices based on natural polymers: effect of process variables on swelling characterization and drug delivery properties (original) (raw)
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Polymer Bulletin, 2014
This paper describes the use of oxidized konjac glucomannan (DAK) as a macromolecular cross-linker for the preparation of gelatinbased pharmaceutical hydrogels, which crosslinked and gelled in minutes. FTIR, XRD, SEM, swelling and mechanical properties experiments were performed to confirm the effect of DAK and evaluate the relationship of the structure and morphology of the hydrogels. The obtained results indicated that DAK promoted the formation of gelatin network. More interestingly, gelatin hydrogels treated by DAK slowed down prominently the release of the model drug ketoprofen, and the release rate could be tailored by the DAK/GL ratio and pH value of buffer solutions. These results suggest that this process offers an entirely new window of material preparation for controlled release of drugs when compared with traditional preparation of gelatin-based hydrogels crosslinked with small molecules.
Polymer Bulletin, 2019
The present research work is focused on development and characterization of copolymerized pectin sulfonic acid hydrogels and to evaluate controlled delivery of captopril. Series of pectin-sulfonic acid-based hydrogels were synthesized by free radical copolymerization technique. Pectin has been chemically cross-linked with 2-acrylamido-2-methylpropane sulfonic acid in the presence of ammonium persulfate and sodium metabisulfite as redox initiator. Methylene bisacrylamide (MBA) was used as cross-linking agent in varying amount to investigate the degree of crosslinking as a function of increased concentration of polymer (pectin) and monomer (AMPS). Captopril was incorporated as model drug in formulated hydrogels. Fourier transform infrared spectroscopy (FTIR) was performed for structural analysis. In vitro swelling and release studies of captopril were carried out at both pH 1.2 and 7.4. Sol-gel fraction was also calculated to determine the amount of uncross-linked polymer fraction in prepared hydrogels. FTIR analysis confirmed the formation of cross-linked network between polymer (pectin) and monomer (AMPS). All formulations showed pH-dependent swelling behavior because of pectin, and drug release pattern was high at pH 1.2, and prolonged release was observed at pH 7.4 because of pH-independent behavior of sulfonic acid. The results of sol-gel analysis confirmed that gel fraction increases as amount of AMPS and MBA was increased. From current research study, it is concluded that stable formulations of pectin-sulfonic acid were formed by optimized copolymerization reaction. This newly developed polymeric network could serve as a potential system for controlled delivery of captopril for prolonged period.
Journal of Materials Science: …, 2008
In the present study an attempt was made to graft polyacrylamide on pectin. The grafted polymer was characterized by FTIR spectroscopy, differential scanning calorimetry and X-ray diffraction. Rheological property of pectin solution was compared with the product solution. The grafted polymer was cross-linked with varying amount of glutaraldehyde. The swelling properties of the crosslinked product were also studied. The salicylic acid, an antipyretic drug, was incorporated in the cross-linked gel as a model drug and the drug release studies were done in a modified Franz's diffusion cell. The effect of cross-linking density on the release property of salicylic acid was studied through the cross-linked product. The product showed better film forming property and gelling property than pectin. The comparative rheological properties of pectin and grafted copolymer indicated change in the property of the product. FTIR studies indicated incorporation of amide group. Differential scanning calorimetry and XRD suggested formation of a new polymer. Swelling study indicated pH dependent swelling of the cross-linked hydrogel. Salicylic acid release indicated pH dependent release from the hydrogel.
Characterization of polysaccharide hydrogels for modified drug delivery
European Biophysics Journal, 2007
Hydrogels are hydrophilic macromolecular networks that are capable of retaining a large amount of water. A precise description of these systems is actually quite complex and the practical use of hydrogels for drug delivery and biomedical applications is often not supported by a well-defined knowledge of the overall structure of the polymeric network. In this paper, we report the characterization of two different systems: a chemical network based on Guar Gum (GG) and a physical gel prepared with Xanthan (Xanth) and Locust Bean Gum (LBG). The dynamo-mechanical properties of the gels were analysed: the cohesiveness and the adhesion of the networks were strongly dependent on time, temperature, and composition. The kinetics of the chemical crosslinking was followed by means of rheological measurements, i.e. recording the mechanical spectra of the gelling system, and the power law exponent at the gel point was evaluated. Furthermore, the networks, loaded with model drugs with different steric hindrance, were used as matrices for tablets and the rate of release of such model drugs was studied. The diffusion of the guest molecules was deeply dependent on their dimensions; in the case of Xanth-LBG tablets the release profiles were almost independent from the different cohesion properties of the starting hydrogel composition.
Crosslinking Methods in Polysaccharide-Based Hydrogels for Drug Delivery Systems
Biomedical Materials & Devices
Polysaccharides are inspiring and valuable molecules to the development of novel drug delivery systems owing to their natural availability, non-toxicity, biocompatibility, good biological performance, and chemical similarity to the physiological environment, besides their noticeable use for tailored-materials assembly. Biodegradable hydrogels based on polysaccharides have been widely studied as potential pharmaceutical forms due to their controlled release properties, which improve drug bioavailability, therapeutic efficacy, and patient compliance. Despite these advantages, polysaccharide materials present insufficient mechanical properties or processability, thus, to overcome these drawbacks, feasible and suitable crosslinking methods are employed to improve polysaccharide hydrogels strength and stability. Therefore, this review presents recent advances in crosslinking methods of polysaccharide hydrogels, including chitosan, cellulose, hyaluronic acid, and alginate, providing examples of manufacturing processes with emphasis in their use as carriers in drug delivery. Polysaccharide-based hydrogels represent a sustainable, biocompatible, and appreciable alternative to obtain novel drug delivery systems.
Journal of Applied Polymer Science, 2019
A series of drug-loaded pectin hydrogels were prepared by mixing method in two ion types, Ca +2 or Zn +2 , for wound dressing applications and their drug release performances were investigated at pH 6.4 in four different calcium ion concentrations of external solution. Pectin hydrogels were synthesized in three different concentrations of initial pectin solution and theophylline was used as a model drug. Fourier transform infrared spectroscopy, scanning electron microscopy, and atomic force microscopy were used for hydrogel characterization. Additionally, fluid handling capacity, swelling behavior, dehydration rate, dispersion characteristic, dressing pH determination, water vapor permeability, oxygen permeability, surface contact angle, flexibility, mass per unit area, and thickness were determined for selected hydrogels. One of the most valuable contributions of our study is that the concentration of initial pectin solution and calcium ion concentration of external solution are very important parameters to obtain an effective drug release. After evaluating all data, we have shown that flexible and transparent pectin-based wound dressings can be synthesized as a controlled drug release system. Zinc-containing hydrogel was antibacterial against Staphylococcus aureus and Escherichia coli but not suitable for cell migration. On the other hand, calcium-based hydrogel was nontoxic on the fibroblast cells and it had no negative effect on cell migration.
Preparation and characterization of amidated pectin based hydrogels for drug delivery system
Journal of Materials Science: …, 2008
In the current studies attempts were made to prepare hydrogels by chemical modification of pectin with ethanolamine (EA) in different proportions. Chemically modified pectin products were crosslinked with glutaraldehyde reagent for preparing hydrogels. The hydrogels were characterized by Fourier transform infrared spectroscopy (FTIR), organic elemental analysis, X-ray diffraction studies (XRD), swelling studies, biocompatibility and hemocompatibility studies. Mechanical properties of the prepared hydrogels were evaluated by tensile test. The hydrogels were loaded with salicylic acid (used as a model drug) and drug release studies were done in a modified Franz's diffusion cell. FTIR spectroscopy indicated the presence of primary and secondary amide absorption bands. XRD studies indicated increase in crystallinity in the hydrogels as compared to unmodified pectin. The degree of amidation (D A ) and molar and mass reaction yields (Y M and Y N ) was calculated based on the results of organic elemental analysis. The hydrogels showed good water holding properties and were found to be compatible with B-16 melanoma cells & human blood.
Carbohydrate Polymers, 2014
The production of injectable pectin hydrogels by internal gelation with calcium carbonate is proposed. The pH of pectin was increased with NaOH or NaHCO 3 to reach physiological values. The determination of the equivalence point provided evidence that the pH can be more precisely modulated with NaHCO 3 than with NaOH. Degradation and inability to gel was observed for pectin solutions with pH 5.35 or higher. Therefore, pectin solutions with pH values varying from 3.2 (native pH) to 3.8 were chosen to produce the gels. The increase of the pH for the crosslinked hydrogels, as well as the reduction of the gelling time and their thickening, was dependent upon the amount of calcium carbonate, as confirmed by rheology. Hydrogel extracts were not cytotoxic for L-929 fibroblasts.
Interpenetrating biopolymer network based hydrogels for an effective drug delivery system
Carbohydrate Polymers, 2012
Discovery of hydrogels has resulted in developing competent controlled-release drug delivery systems. Present study describes the synthesis and characterization of novel pH responsive hydrogels of chitosan, hydroxyl ethyl cellulose (HEC) and polyol prepared by physical blending of the three components in different ratios. Vegetable oil derived polyol seems to act as a filler and cross linking agent. The synthesized hydrogels were characterized using FT-IR spectroscopy, thermo gravimetric analysis (TGA), Optical microscopy and scanning electron microscopy (SEM). Equilibrium swelling behavior of hydrogels in water and different buffers with pH values (2, 4, 7.3, and 8) indicated the sustained expansion of the films in different pH solutions.
Crosslinked natural hydrogels for drug delivery systems
Journal of Composites and Compounds
Hydrogels made from a variety of materials may be used as a novel technology in regenerative medicine in the biomedical field. Hydrogels may be made using both chemical and physical processes, depending on the source material. Size, elastic modulus, swelling, and degradation rate are only a few of the many physical parameters that may be used to define hydrogels in experiments. Hydrogels made from natural polymers have been the focus of our review. Due to their remarkable biocompatibility and nontoxicity, simple gelation, and functionalization, hydrogels derived from natural polymers have received extensive attention in recent decades. As a result, natural polymer hydrogels are considered excellent biomaterials that have great potential in the biomedical field. Because carriers play such a large role in determining how far and how fast drugs reach their intended recipients, the need for intelligent drug delivery systems (DDSs) is on the rise. An outstanding goal of this study is to examine the impact that various crosslinking process parameters have on the drug delivery mechanism.