Controlled release of diclofenac sodium and ibuprofen through beads of sodium alginate and hydroxy ethyl cellulose blends

Controlled release of diclofenac sodium (DS) and ibuprofen (IB) drugs through sodium alginate (NaAlg)‐hydroxy ethyl cellulose (HEC) blend polymeric beads has been investigated. Beads were prepared by precipitating the viscous solution of NaAlg and HEC blend in alcohol followed by crosslinking with calcium chloride. Different formulations were developed in bead form by varying the amount of HEC, crosslinking agent, and drug concentration. Swelling studies in water, percent encapsulation of drugs, and release studies were carried out. The DS‐loaded beads have shown better release performance than the IB‐loaded beads. Diffusion parameters were evaluated from the Fickian diffusion theory. Mathematical modeling studies and drug release characteristics through bead matrices were studied by solving Fick's diffusion equation. The results are discussed in terms of drug release patterns and theoretical concentration profiles generated through matrices, considering spherical geometry of the beads. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 5708–5718, 2006     

Semi‐interpenetrating polymer network beads of crosslinked chitosan–glycine for controlled release of chlorphenramine maleate

Spherical, semi‐interpenetrating polymer network beads of chitosan and glycine, crosslinked with different concentrations of glutaraldehyde were prepared for controlled release of drugs. The structural and morphological studies of the beads were carried out with FTIR and SEM techniques. The swelling behavior of the beads at different time intervals was monitored in solutions of different pH. Structural changes of the beads in response to solution pH were put forward using the data obtained from IR/UV spectral analysis. The release experiments were performed in solutions of pH 2.0 and pH 7.4 at 37°C, using chlorphenramine maleate as a model drug. The results indicate that, chitosan might be useful as a vehicle for controlled release of drugs. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 76: 672–683, 2000     

Polymeric sodium alginate interpenetrating network beads for the controlled release of chlorpyrifos

Novel polymeric sodium alginate (Na‐Alg) interpenetrating network (IPN) beads have been prepared by crosslinking Na‐Alg blend with gelatin (GE) or egg albumin (EA) using glutaraldehyde (GA) as the crosslinking agent. These beads were used for the controlled release of chlorpyrifos. The swelling experiments were performed in water at different temperatures, and these data were used to calculate the molecular mass (M_C) between crosslinks as well as diffusion coefficients. Diffusion coefficients calculated from desorption data were lower by about two orders of magnitude than those calculated from sorption results. Higher values of M_C were obtained for the gelatin‐based IPNs than the neat Na‐Alg and egg albumin‐based matrices. Size of the beads did not vary significantly either by the network or by increasing the exposure time to the crosslinking agent. The scanning electron microscopy (SEM) was used to understand the surface characteristics of the beads. Differential scanning calorimetry (DSC) indicated a molecular level dispersion of chlorpyrifos in the polymer matrix. The percentage entrapment efficiency showed a dependence on the type of network polymer as well as time of exposure to the crosslinking agent. The encapsulation efficiency decreased with an increase in time of exposure to the crosslinking agent. In vitro release experiments have been performed to follow the release kinetics of chlorpyrifos from the matrices. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 911–918, 2002     

Semiinterpenetrating polymer networks of chitosan and L‐alanine for monitoring the release of chlorpheniramine maleate

In vitro studies have been carried on semiinterpenetrating polymer network (IPN) beads of chitosan–alanine as carrier for the controlled release of chlorpheniramine maleate (CPM) drug. A viscous solution of chitosan–alanine was prepared in 2% acetic acid solution, extruded as droplets by a syringe to NaOH–methanol solution and crosslinked using glutaraldehyde as a crosslinker. The swelling behavior of crosslinked beads in different pH solutions was measured at different time intervals. The swelling behavior was observed to be dependent on pH and degree of crosslinking. The structural and morphological studies of beads were carried out by using a scanning electron microscope. The drug release experiments of different drug loading capacity beads were performed in solutions of pH 2 and pH 7.4 using CPM as a model drug. The concentration of the released drug was evaluated using UV spectrophotometer. The results suggest that chitosan–alanine crosslinked beads are suitable for controlled release of drug. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 3751–3757, 2007     

Temperature sensitive semi‐IPN microspheres from sodium alginate and N‐isopropylacrylamide for controlled release of 5‐fluorouracil

Semi‐interpenetrating network (IPN) of sodium alginate (NaAlg) and N‐isopropylacrylamide (NIPAAm) microspheres were prepared by water‐in‐oil (w/o) emulsification method. The microspheres were encapsulated with 5‐fluorouracil (5‐FU) and release patterns carried in 7.4 pH at temperatures of 25 and 37°C. The semi‐IPN microspheres were characterized by Fourier transform infrared spectroscopy (FTIR). Differential scanning calorimetry (DSC) and scanning electron microscopic studies were done on the drug‐loaded microspheres to confirm the polymorphism of 5‐FU and surface morphology of microspheres. These results indicated the molecular level dispersion of 5‐FU in the semi‐IPN microspheres. Particle size and size distribution were studied by laser light diffraction technique. Microspheres exhibited release of 5‐FU up to 12 h. The swelling studies were carried in 1.2 and 7.4 pH buffer media at 25 and 37°C. Drug release from NaAlg‐NIPAAm semi‐IPN microspheres at 25 and 37°C confirmed the thermosensitive nature by in vitro dissolution. The micro domains have released in a controlled manner due the presence of NIPAAm in the matrix. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Studies on semi‐interpenetrating polymer network beads of chitosan–poly(ethylene glycol) for the controlled release of drugs

Semi‐interpenetrating polymer network beads of chitosan and poly(ethylene glycol) were prepared and characterized for controlled release of drugs. A viscous solution of chitosan and poly(ethylene glycol) in 2% acetic acid was extruded as droplets with the help of a syringe and crosslinked using glutaraldehyde. The structural studies of the beads were performed by using a Fourier transform infrared spectrophotometer and scanning electron microscope. The swelling behavior, solubility, hydrolytic degradation, and loading capacity of the beads for isoniazid were investigated. The structural changes of the beads at pH 2.0 and 7.4 were put forward using the data obtained by infrared and ultraviolet spectroscopy. The prepared beads showed 82% drug‐loading capacity, which suggested that these semi‐interpenetrating polymer network beads are suitable for controlled release of drugs in an oral sustained delivery system. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 639–649, 2001     

Thermoresponsive sodium alginate‐g‐poly(N‐isopropylacrylamide) copolymers III. Solution properties

Stimuli‐responsive biocompatible and biodegradable materials can be obtained by combining polysaccharides with polymers exhibiting lower critical solution temperature (LCST) phase behavior, such as poly(N‐isopropylacrylamide) (PNIPAAm). The behavior of aqueous solutions of sodium alginate (NaAl) grafted with PNIPAAm (NaAl‐g‐PNIPAAm) copolymers as a function of composition and temperature is presented. The products obtained exhibit a remarkable thermothickening behavior in aqueous solutions if the degree of grafting, the concentration, and the temperature are higher than some critical values. The sol–gel‐phase transition temperatures have been determined. It was found that at temperatures below LCST the systems behave like a solution, whereas at temperatures above LCST, the solutions behave like a stiff gel, because of PNIPAAm segregation. This behavior is reversible and could find applications in tissue engineering and drug delivery systems. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

丙烯腈接枝改性海藻酸钙水凝胶中水杨酸的释放行为

将海藻酸钙水凝胶与丙烯腈单体进行不同程度的接枝共聚改性,再由FTIR加以分析,并测定包埋了水杨酸模拟药物的改性海藻酸钙水凝胶在不同介质中的药物释放量。实验表明,改性海藻酸钙水凝胶的药物释放量既与介质有关,也取决于接枝率的大小。     

Preparation and characterization of dual responsive sodium alginate‐g‐poly(vinyl alcohol) hydrogel

Poly(vinyl alcohol) (PVA) was chosen as a controllable gelator to prepare sodium alginate (SA)‐based physically cross‐linked dual‐responsive hydrogel by three steps. First, polyvinyl acetate (PVAc) was grafted onto SA via radical copolymerization. Then, the copolymer was subsequently converted into SA‐g‐poly(vinyl alcohol) (SAPVA) by alcoholysis reaction. PVA content of SAPVA was tailored by controlling the graft percentage of PVAc, i.e. through varying the amount of vinyl acetate during copolymerization. Finally, SAPVA hydrogels were formed by freezing‐thawing cycles. The structure of the graft copolymers was verified with FTIR spectroscopy. X‐ray diffraction analysis results revealed that the crystallinity of SAPVA hydrogels depended on the PVA content of SAPVA. The swelling test showed that SAPVA hydrogels were pH‐responsive, and the swelling was reversible. SAPVA hydrogels also behaved electric‐responsive. In addition, the pH‐sensitivity of SAPVA hydrogels was able to be controlled with the composition of the hydrogels. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

载药蒙脱石/海藻酸钠凝胶球的制备和释放性能

以离子交换方式将硫酸氢氯吡格雷插入蒙脱石层间,再用海藻酸钠包衣得到凝胶球。利用XRD、FTIR进行表征以及体外释放实验检测缓释效果。结果表明,硫酸氢氯吡格雷成功地插入蒙脱石层间,蒙脱石的层间距由1.25 nm增大到1.48 nm;体外释放实验显示在1 h内载药凝胶球的累积释放量为12.9%,表明载药蒙脱石/海藻酸钠凝胶球能明显的减少药物突释,因此可将它作为硫酸氢氯吡格雷的缓释载体。     

Preparation,characterization and release profiles of pH‐sensitive chitosan beads

Spherical crosslinked beads using chitosan, glycine and glutaraldehyde were prepared for controlled release formulations. Structural investigation of the beads was made with IR analysis. Morphological study of the beads was carried out by scanning electron microscopy. The swelling behaviour of the beads was monitored as a function of time in solutions of different pH. The release experiments were performed using thiamine hydrochloride (Thi‐HCl) as a model drug. These preliminary results suggest the possibility of modifying the formulations to obtain the desired controlled release of drug in an oral sustained delivery system. © 2000 Society of Chemical Industry     

Glutaraldehyde‐crosslinked chitosan beads for controlled release of diclofenac sodium

An inexpensive and simple method was adopted for the preparation of chitosan beads, crosslinked with glutaraldehyde (GA), for the controlled release of diclofenac sodium (DS). The beads were prepared by varying the experimental conditions such as pH, temperature, and extent of crosslinking. The absence of any chemical interaction among drug, polymer, and the crosslinking agent was confirmed by FTIR and thermal analysis. The beads were characterized by microscopy, which indicated that the particles were in the size range of 500–700 μm and SEM studies revealed smooth surface and spherical shape of beads. The beads produced at higher temperature and extended exposure to GA exhibited lower drug content, whereas increased drug loading resulted in enhanced drug release. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 211–217, 2007     

pH sensitive interpenetrating network microgels of sodium alginate‐acrylic acid for the controlled release of ibuprofen

pH‐Sensitive interpenetrating network (IPN) microgels (MGs) of sodium alginate (NaAlg) and acrylic acid have been prepared by using water‐in‐oil (W/O) emulsion technique. The MGs were characterized by Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), X‐ray diffractometer (X‐RD). The release of ibuprofen (IB), an anti‐inflammatory drug, from these MGs was studied in pH 1.2 and 7.4 media. MG network consists of NaAlg, which disintegrates in the intestinal fluid, while poly(acrylic acid) provides pH‐sensitivity to the microgel network. The system developed in this study showed a pH‐sensitivity for the release of IB, which was attributed to the diffusion controlled release of the drug through the surfaces of MGs that undergo disintegration after swelling, depending upon the chemical composition of MGs and pH of the medium. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci, 2006     

Preparation and characterization of interpenetrating network beads of poly(vinyl alcohol)‐grafted‐poly(acrylamide) with sodium alginate and their controlled release characteristics for cypermethrin pesticide

Interpenetrating network polymeric beads of poly(vinyl alcohol)‐grafted‐acrylamide with sodium alginate have been prepared by crosslinking with glutaraldehyde. Cypermethrin, a widely used pesticide, was loaded with 80% efficiency in these hydrogel beads. The beads were characterized by Fourier transform infrared spectroscopy to confirm the grafting. Scanning electron microscopy was used to know the morphology of the beads. Equilibrium swelling experiments indicated that swelling of the beads decreased with an increase in crosslinking. The in vitro release studies were performed under static conditions and the release data have been fitted to an empirical relation to estimate the transport parameters. The diffusion coefficients have been calculated for the transport of pesticide through the polymeric beads using the initial time approximation method. These values showed decrease with increasing crosslinking as well as increasing pesticide loading. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 552–560, 2002; DOI 10.1002/app.10306     

Controlled release study of carbaryl insecticide from calcium alginate and nickel alginate hydrogel beads

In this study, controlled release formulations for reducing environmental impact of pesticides have been produced by encapsulating as a model pesticide carbaryl (Carb) in the alginate beads. The various hydrogel bead formulations were prepared by the ionotropic crosslinking of sodium alginate (NaAlg) with calcium and nickel ions. The surface morphology of prepared beads was characterized with scanning electron microscopy (SEM). SEM confirmed the spherical nature and surface morphology of the particles. Bead characteristics, such as carbaryl entrapment efficiency, particle size, equilibrium swelling degree, and carbaryl release kinetics, were determined. The effects of the bead preparation conditions such as crosslinker concentration and type, carbaryl/sodium alginate (Carb/NaAlg) ratio and percentage of NaAlg on the carbaryl release from the calcium alginate (Ca‐Alg) and nickel alginate (Ni‐Alg) beads were investigated in distilled water at 25°C. It was observed that carbaryl release from the Ca‐Alg beads was slower than that of Ni‐Alg beads. The release results indicated that carbaryl release from both of the Ca‐Alg and Ni‐Alg beads decreases with the increasing crosslinker concentration, Carb/NaAlg ratio and percentage of NaAlg. The highest carbaryl release was found to be 100% for the Ni‐Alg beads at 3 days whereas the lowest carbaryl release was found to be 67% for the Ca‐Alg beads at 21 days. The swelling measurements of the beads were also in consistent with the carbaryl release results. The carbaryl release from most of the bead formulations followed Case II transport. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Controlled release of carboxylic‐containing herbicides by starch‐g‐poly(butyl acrylate)

The use of starch‐g‐poly(butyl acrylate) as a new material for encapsulating carboxylic‐containing herbicides such as 2,4‐dichlorophenoxyacetic acid and 2,4,5‐trichlorophenoxyacetic acid for controlled release was studied. The herbicides were individually encapsulated within the modified starch substrate, which was graft‐copolymerized with a small amount of butyl acrylate. The modification of starch induced a hydrophobic behavior in the matrix, made it swell less, and caused the release rate to slow, especially for herbicides with higher water solubility. Therefore, the survival life of the starch products for controlled release could be expected to extend to some extent compared with that of natural starch. In addition, the effects of the molecular weight, herbicide content, and particle size on the swellability and release behavior were also investigated. Scanning electron microscopy revealed that the herbicides encapsulated within the starch matrix were dispersed in the form of tiny cell. Consequently, the herbicides encapsulated were released through diffusion. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 1535–1543, 2001     

Controlled release formulations of carbaryl based on copper alginate,barium alginate,and alginic acid beads

A controlled release system for reducing environmental impact was produced by encapsulating the pesticide carbaryl (Carb) in the alginate beads. The various bead formulations were prepared by using sodium alginate (NaAlg) as a polymer, CuCl₂, BaCl₂ as a crosslinking agent, and HCl as a linking agent. The surface morphology of prepared beads was characterized with scanning electron microscopy (SEM). SEM confirmed the spherical nature and surface morphology of the particles. Bead characteristics, such as Carb entrapment efficiency, particle size, swelling degree, and Carb release kinetics, were determined. The effects of crosslinker or linker concentration, type, and carbaryl/sodium alginate (Carb/NaAlg) ratio on Carb release from the beads were investigated for 20 days at 25°C. It was observed that Carb release from the beads increased with the increase of Carb/NaAlg ratio whereas decreased with the increase of crosslinker concentration. At the end of 20 days, the Carb release from alginic acid beads was found to be higher than that of copper alginate (Cu‐Alg) and barium alginate (Ba‐Alg) beads. The swelling measurements of the beads supported the release results. Release kinetics were described by Fickian and non‐Fickian approaches. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 4245–4253, 2006     

Adsorption of lanthanum by magnetic alginate‐chitosan gel beads

BACKGROUND: The risk of environmental pollution is aggravated by the increasing application of considerable amounts of rare earth elements in advanced materials. This paper reports the preparation of novel magnetic alginate–chitosan gel beads and their application for adsorption of lanthanum ions from aqueous solution. RESULTS: Stable magnetic alginate–chitosan gel beads with average diameter 0.85 ± 0.05 mm were prepared by loading iron oxide nanoparticles onto a combined alginate and chitosan absorbent. The performance of the prepared beads for the adsorption of lanthanum ions from aqueous solution was tested. It was found that various parameters, such as aqueous pH, contact time, metal ion concentration, ion strength and temperature, have an effect on the adsorption. Adsorption equilibrium was reached in 10 h and the maximum uptake capacity was 97.1 mg g^?1. From the analysis of pH, FTIR and XPS data, it is proposed that lanthanum adsorption proceeds through mechanisms of cation exchange, electrostatic interaction and surface complexation, with the oxygen atoms the main binding sites. In addition, lanthanum ions could be selectively separated from coexisting base metal ions such as Pb (II), Cd (II), Co (II), Ni (II) and Cu (II) in the aqueous solution. CONCLUSION: The prepared magnetic alginate–chitosan gel beads exhibit high uptake capacity and selectivity for lanthanum sorption, and thus can be used for adsorptive recovery of lanthanum from aqueous solutions. Copyright © 2010 Society of Chemical Industry     

Effectiveness test of alginate‐derived polymeric surfactants

A series of alginate‐derived polymeric surfactants (APSs) with a linear alkyl group (C8, C12, C16) was synthesized by oxidation followed by reductive amination of 2,3‐dialdehydic alginate. The products were characterized by measuring IR spectra, NMR spectra, surface tension and critical micelle concentration (cmc). They were also tested for the solubilization of azobenzene and adsorption of heavy metal. In the case of 40% CHO‐C8 APSs, the lowest interfacial tension value (31.5 m Nm^?1) was obtained at the cmc value of 1.35 g dm^?3. The dissolving capacity of 40% CHO‐C8 APS towards azobenzene was 27 times greater than that of alginate. The overall cobalt (Co²⁺) removal efficiency by adsorption using APSs was high compared with that of sodium alginate at pH 3, 5 and 7. Equilibrium aspects of cobalt adsorption onto 10% CHO‐APSs were studied, and the results show that APSs had high equilibrium capacities for cobalt uptake, 115.5 mgg^?1. © 2002 Society of Chemical Industry     

In vitro degradation and protein release of semi‐IPN hydrogels consisted of poly(acrylic acid‐acrylamide‐methacrylate) and amylose

The enzymatic degradation mechanism of semi‐interpenetrating network (semi‐IPN) hydrogel of poly (acrylic acid‐acrylamide‐methacrylate) crosslinked by azocompound and amylose in vitro was investigated in the presence of Fungamyl 800L (α‐amylase) and rat cecum content (cecum bacteria). The degradation mechanism involves degradable competition, i.e., reduction of azo crosslinkage is dominant in the earlier period of degradation. Subsequently, the degradation of gels is continued by combination of reduction of azo crosslinkage and hydrolysis of amylose. The cumulative release ratios of Bovine serum albumin (BSA, as a model drug) loaded semi‐IPN gels are 25% in pH 2.2 buffer solutions and 74% in pH 7.4 buffer solutions within 48 h. Moreover, the release behavior of BSA from the semi‐IPN gels indicates that it follows Fickian diffusion mechanism in pH 2.2 media and non‐Fickian diffusion and polymer chains relaxation mechanism in pH 7.4 media. The results indicate that the release of BSA from the semi‐IPN gels was controlled via a combined mechanism of pH dependent swelling and specificity to enzymatic degradation. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007