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1.
Recently, much attention has been focused on the development of gel based formulations for controlled drug delivery applications. Herein, we report the effect of the ionic (gum acacia) and the non‐ionic (guar gum) gums on the properties of the bigels prepared with fluid‐filled organogels. The microscopic study suggested the presence of flocculated structure in guar gum bigel, whereas, a de‐flocculated structure was observed in gum acacia bigel. Infrared spectroscopy suggested the presence of polysaccharides in the bigels. The mechanical properties of the guar gum bigel were better than gum acacia bigel. The conductivity and the release properties suggested superior properties of gum acacia bigel. This indicated that the ionic nature of acacia bigel played a major role in controlled drug delivery, making it a potential bigel for desired pharmaceutical applications. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42561.  相似文献   

2.
The potential of gum acacia containing hydrogels as controlled dual‐drug delivery systems for antiprotozoal agents was investigated. 4‐Aminoquinoline analog and curcumin were selected as model drugs because they exhibit antiprotozoal activity. The maximum release time was greater for curcumin than for the 4‐aminoquinoline analog at 37°C, thereby enabling the active ingredients to work over different periods of time. 4‐Aminoquinoline analog exhibited a short term release profile while curcumin exhibited a sustained and long term release profile. The release profiles of the drugs were found to be influenced by the degree of crosslinking of the hydrogel network with gum acacia. The release profiles were analyzed using a power law equation proposed by Peppas. The release mechanism of the 4‐aminoquinoline was found to be anomalous transport while that of curcumin was quasi‐Fickian diffusion mechanism in all the hydrogel networks according to the release exponent. The preliminary results suggest that these systems are potential dual‐drug delivery system for antiprotozoal agents with different pharmacokinetics. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41613.  相似文献   

3.
A series of pH‐responsive hydrogels were studied as potential drug carriers for the protection of insulin from the acidic environment of the stomach before releasing in the small intestine. Hydrogels based on poly(vinyl alcohol) networks grafted with acrylic acid or methacrylic acid were prepared by a two‐step process. Poly(vinyl alcohol) hydrogels were prepared by gamma ray irradiation (50 kGy) and then followed by grafting either acrylic acid or methacrylic acid onto these poly(vinyl alcohol) hydrogels with subsequent irradiation (5–20 kGy). These graft hydrogels showed pH‐sensitive swelling behavior and were used as carriers for the controlled release of insulin. The in vitro release of insulin was observed for the insulin‐loaded hydrogels in a simulated intestinal fluid (pH 6.8) but not in a simulated gastric fluid (pH 1.2). The release behavior of insulin in vivo in a rat model confirmed the effectiveness of the oral delivery of insulin to control the level of glucose. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 636–643, 2004  相似文献   

4.
In the present work, a nanocomposite hydrogel is designed consisting of gum acacia, poly(acrylamide) and carbon nitride by facile microwave approach. This nanocomposite hydrogel is sensitive to environmental stimuli which is essential for its application in environmental remediation and as a drug delivery system. The effects of carbon nitride percentage and microwave Watt variation on swelling capacity of gum acacia‐cl‐poly(acrylamide)@carbon nitride (Ga‐cl‐PAM@C3N4) nanocomposite hydrogel are analyzed. The structural characterizations are considered by numerous techniques such as FTIR (Fourier transform infra‐red spectroscopy), X‐ray diffraction, transmission electron microscopy, scanning electron microscopy, and elemental mapping. Batch experiment is performed for remediation of ciprofloxacin (CIP) drug from water. Various parameters such as effect of ciprofloxacin doses, Ga‐cl‐PAM@C3N4 nanocomposite hydrogel dosage, pH, time and temperature for adsorption of CIP on gum acacia‐cl‐poly(acrylamide)@carbon nitride nanocomposite hydrogel is examined. Maximum adsorption capacity of Ga‐cl‐PAM@C3N4 nanocomposite hydrogel observed is 169.49 mg g?1 at pH 6.4. The drug loading and drug release capacity of Ga‐cl‐PAM@C3N4 nanocomposite hydrogel is investigated for ciprofloxacin. Drug release is monitored in artificial ocular solution (pH 8), saline (pH 5.5), acetate buffer (pH 2.2), and distilled water. Maximum drug release is observed in artificial ocular solution.  相似文献   

5.
The aim of the study was to prepare the controlled release dosage of carbamazepine matrix tablets using wet granulation technique. The graft copolymerization of carboxymethyl chitosan (CMCH) with 2‐hydroxyethylmethacrylate (HEMA) was carried out. The product was characterized by Fourier‐transform infrared, scanning electron microscopy, transmission electron micrograph, and X‐ray diffraction anayses. CMCH‐g‐HEMA was used as binder to prepare the matrix tablets containing carbamazepine. The properties of tablets like hardness, friability, and dissolution influenced by binder were studied. In vitro release of the matrix tablets was carried out with the phosphate‐buffered solution (pH 7.4) at 37°C and 100 × g using USP dissolution test apparatus. Release rate of carbamazepine from controlled release matrix tablets was compared with the commercially marketed tablet, Tagretol 200. Results show that after 6 hrs percentage drug release of formulated tablet CGH5 was 20.42% and that of Tegretol 200 was 18.32%. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010  相似文献   

6.
Naturally available carbohydrate polymers such as methylcellulose (MC) and gelatin (Ge) have been widely studied in the previous literature for controlled release (CR) applications. In this study, methyl cellulose‐g‐acrylamide/gelatin (MC‐g‐AAm/Ge) microspheres were prepared by water‐in‐oil (W/O) emulsion method and crosslinked with glutaraldehyde to encapsulate with nifedipine (NFD), an antihypertensive drug. The microspheres prepared were characterized by differential scanning calorimetry (DSC), scanning electron microscopy (SEM), and laser particle size analyzer. DSC thermograms of NFD‐loaded AAm‐MC/Gel microspheres confirmed the molecular level distribution of NFD in the matrix. SEM indicated the formation of spherical particles. Swelling experiments supported the drug diffusion characteristics and release data of the matrices. Cumulative release data were analyzed using an empirical equation to understand the nature of transport of drug through the matrices. Controlled release characteristics of the matrices for NFD were investigated in pH 7.4 media. Drug was released in a controlled manner up to 12 h. Particle size and size distribution of the microspheres as studied by laser light diffraction particle size analyzer indicated their sizes to be around 120 μm. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010  相似文献   

7.
A gellan gum–Jeffamine superabsorbent hydrogel was obtained with different crosslink densities using different amounts of (1‐ethyl‐3‐(3‐dimethylaminopropyl)carbodiimide hydrochloride) and N‐hydroxysuccinimide. Infrared spectroscopy and thermal analysis confirm the crosslinking. A morphology analysis indicates denser structures for samples with higher crosslinking points. The swelling degree in high‐acyl gellan gum hydrogels was equivalent to 145 times their dry weight, and 77 times when low‐acyl gellan gum was used. Hydrogels also showed a 450 min water retention, as opposed to 280 min for pure water, evidencing good humidity control, suitable for use in arid climates. They also demonstrated a maximum release of commercial fertilizer of about 400 mg per gram for KH2PO4 and about 300 mg per gram for NPK 20‐5‐20. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45636.  相似文献   

8.
The morphology and mechanical properties of PVC/SMA‐g‐PA6 blends were investigated in this paper. Graft to polymer SMA‐g‐PA6 was prepared via a solution graft reaction between SMA and PA6. FTIR test evidences the occurrence of the graft reaction between SMA and PA6. DSC analysis shows that SMA‐g‐PA6 has a lower melting point of 187°C, which may result in a decrease in crystallinity of PA6 and thus enable efficient blending of SMA‐g‐PA6 and PVC. Compatibilization was evidenced by the dramatic increase in mechanical properties, the smaller particle size and finer dispersion of PA6 in PVC matrix, and, further, a cocontinuous morphology at 16 wt % SMA‐g‐PA6 content. SMA‐g‐PA6 from the solution graft reaction can toughen and reinforce PVC material. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 432–439, 2004  相似文献   

9.
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  相似文献   

10.
Graft copolymer of N‐vinyl‐2‐pyrrolidone with guar gum was synthesized and its reaction conditions were optimized for better yield using potassium peroxymonosulfate (PMS) and glycolic acid (GA) as a redox initiator. The effect of PMS, GA, hydrogen ions, guar gum, and N‐vinyl‐2‐pyrrolidone (NVP) along with reaction time and temperature were studied by determining the grafting parameters: grafting ratio, efficiency, conversion, add‐on, homopolymer, and rate of grafting. It was observed that the maximum yield occurred at with a time of 120 min at a temperature of 45°C and a guar gum concentration of 0.4 g/L concentration. The graft copolymer was characterized by infrared spectroscopy and thermal analysis. The activation energy for the grafted and ungrafted gum was calculated. It was observed that the graft copolymer was thermally more stable than the pure gum. The swelling and metal ion sorption behavior of guar gum and guar gum‐gN‐vinyl‐2‐pyrrolidone also were studied. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 2480–2489, 2006  相似文献   

11.
Chitosan‐g‐poly(vinyl alcohol) (PVA) copolymers with different grafting percent were prepared by grafting water‐soluble PVA onto chitosan. The drug‐release behavior was studied using the chitosan‐g‐PVA copolymer matrix containing prednisolone in a drug‐delivery system under various conditions. The relationship between the amount of the released drug and the square root of time was linear. From this result, the drug‐release behavior through the chitosan‐g‐PVA copolymer matrix is shown to be consistent with Higuchi's diffusion model. The drug‐release apparent constant (KH) was slightly decreased at pH 1.2, but increased at pH 7.4 and 10 according to the increasing PVA grafting percent. Also, KH was decreased by heat treatment and crosslinking. The drug release behavior of the chitosan‐g‐PVA copolymer matrix was able to be controlled by the PVA grafting percent, heat treatment, or crosslinking and was also less affected by the pH values than was the chitosan matrix. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 458–464, 1999  相似文献   

12.
A xanthan gum‐gN‐vinyl formamide graft copolymer was synthesized through the graft copolymerization of N‐vinyl formamide (NVF) onto xanthan gum with an efficient system, that is, potassium monopersulfate (PMS)/Ag(I) in an aqueous medium. The effects of the concentrations of Ag(I), PMS (KHSO5), hydrogen ion, xanthan gum, and NVF along with the time and temperature on the graft copolymerization were studied by the determination of the grafting parameters (grafting ratio, add‐on, conversion, grafting efficiency, and homopolymer) and the rate of grafting. The maximum grafting ratio was obtained at a 0.6 g/dm3 concentration of xanthan gum. All the parameters showed an increasing trend with an increasing concentration of peroxymonosulfate, except the homopolymer percentage, which showed a decreasing trend. The grafting ratio, add‐on conversion, grafting efficiency, and rate of grafting increased with the concentration of Ag(I) increasing from 0.8 × 10?2 to 1.2 × 10?2 mol/dm3. The optimum time and temperature for the maximum degree of grafting were 90 min and 35°C, respectively. The graft copolymer was characterized with IR spectral analysis, thermogravimetric analysis, and differential calorimetry analysis. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 1637–1645, 2006  相似文献   

13.
Poly(N‐vinylpyrrolidone) (PVP) groups were grafted onto poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate) (PHBV) backbone to modify the properties of PHBV and synthesize a new novel biocompatible graft copolymer. Based on these graft copolymers, electrospun fiber mats and commonly cast films were explored as drug delivery vehicles using tetracycline hydrochloride as a model drug. Toward that end, the fibers were electrospun and the films were cast from chloroform solutions containing a small amount of methanol to solubilize the drug. The Brookfield viscosities of the solution were determined to achieve the optimal electrospinning conditions. The vitro release of the tetracycline hydrochloride from these new drug delivery systems was followed by UV–vis spectroscopy. To probe into the factors affected on the release behavior of these drug delivery systems, their water absorbing abilities in phosphate buffer solution were investigated, together with their surface hydrophilicity, porosity and crystallization properties were characterized by water contact angles, capillary flow porometer, DSC, and WAXD, respectively. The morphological changes of these drug delivery vehicles before and after release were also observed with SEM. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012  相似文献   

14.
In this study, amphiphilic graft copolypeptides containing L ‐tryptophan (Trp) were prepared by aminolysis reaction of poly(γ‐benzyl L ‐glutamate)‐graft‐poly(Trp) with 2‐amino‐1‐ethanol and then treated with trifluoroacetic acid (TFA). Graft copolypeptide hydrogel membranes treated with TFA were also obtained by same method as the graft copolypeptide in the presence of crosslinking agent. By using these graft copolypeptides and hydrogel membranes, aggregation behaviour and sustained‐release of hydrophobic substance were investigated. In aqueous medium, graft copolypeptides formed aggregates 90 nm in diameter and exhibited the ability to uptake hydrophobic substances into their hydrophobic moiety. TFA‐treated graft copolypeptide showed a pH response; the diameter and uptake ability of the graft copolypeptide were decreased below pH 2.0. This pH response is due to the dissociation of the indole ring of Trp treated with TFA in this pH region. The pH response of drug release from hydrogel membrane treated with TFA was also observed. The hydrophobic drug, testosterone, was released continuously at pH 2.0, whereas the release of testosterone was depressed at pH 5.0. These results can be explained by aggregation and dissociation of Trp residues in the graft copolypeptide. Copyright © 2004 Society of Chemical Industry  相似文献   

15.
5‐Fluorouracil (5‐Fu) loaded poly(glycolide‐co‐lactide‐co‐caprolactone) (PGLC) nanoparticles were prepared by modified spontaneous emulsification solvent diffusion method (modified‐SESD method) and characterized by dynamic light scattering, scanning electron microscopy and 1H NMR determination. It was found that the obtained nanoparticles showed near spherical shape and was controllable with the radius range of 30–100 nm. Compared with the nanoparticles prepared by polylactide and poly (lactide‐co‐glycolide) (PLGA) under the similar preparation condition, yield of PGLC nanoparticles was the highest, which reached to about 100%. On the other hand, drug entrapment efficiency of PGLC nanoparticles was also higher than that of PLGA and PLLA nanoparticles. 5‐Fu release behavior of PGLC nanoparticles in vitro showed that 5‐Fu release of PGLC nanoparticles showed a near zero‐order release profile, and 5‐Fu release rate of PGLC nanoparticles was faster than that of PLLA and PLGA nanoparticles. According to degradation behavior of PGLC nanoparticles, it could be proposed that the kinetic of degradation controlled release played an important role in the release process of PGLC nanoparticles. It revealed that the PGLC nanoparticles could be a promising drug carrier. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007  相似文献   

16.
Rheological properties, blend compatibility, and gel‐forming capacity of carbopol 940 (CP‐940), sodium alginate (NaAlg), and guar gum (GG) have been studied. These matrices have been used in delivery of timolol maleate for ophthalmic applications. Aqueous solutions of CP‐940, NaAlg, and GG in concentrations between 0.1 and 1% (wt/vol) and their blends have been prepared. In situ gel forming polymeric solutions have shown an increase in viscosity upon exposure to specific pH, ions, and temperature of the eyeball. Blend miscibility was studied by calculating polymer–polymer interaction parameters using viscosity data. Rheological properties viz., torque, viscosity, shear stress, and shear rate were obtained using a Brookfield rheometer. Viscosities of polymer solutions were obtained by a Schott Gerate viscometer. Rheological data were analyzed using Bingham, Casson Standard, and Casson Chocolate equations. The hydrogels were subjected to ex vivo release studies on timolol maleate through the excised bovine cornea using a modified Franz diffusion cell. Results were compared with the conventional drug solution. The release could be extended when the drug is incorporated into hydrogel‐forming solution. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 2057–2064, 2004  相似文献   

17.
Starch/(Ethylene glycol‐co‐Methacrylic acid) [Starch/(EG‐co‐MAA)] hydrogels were designed for controlled delivery of pesticides, such as Fluometuron (FH); Thiophanate Methyl (TF) and Trifluralin (TI) which are use in the agricultural field. The delivery device was prepared by using γ‐irradiation and was characterized by FTIR, DSC, and SEM. The swelling behavior of hydrogels as a function of copolymer composition and irradiation dose was detected. This article discusses the swelling kinetics of polymer matrix and release dynamics of Trifluralin from hydrogels for the evaluation of the diffusion mechanism and diffusion coefficients. The values of the diffusion exponent ‘n’ for both the swelling of hydrogels and the release of Trifluralin from the hydrogels have been observed between 0.56 and 0.86 when the MAA content in the polymers was varied from 20 to 80 wt %, respectively. It is inferred from the values of the ‘n’ that non‐Fickian diffusion mechanism has occurred for different EG/MAA compositions. The release rate from matrices prepared under different conditions was studied to determine which factors have the most affect and control over the hydrogel matrix release property. The preparation conditions such as EG/MAA hydrogel composition, pesticide concentration, type of pesticide and irradiation dose greatly affect the pesticide release rate, which also influenced by the pH and temperature of the matrix‐surrounding medium. The pesticide release rate decreased as the irradiation dose and pH increased, but it increased as the MAA content, pesticide concentration and temperature increased. The release rate of Trifluralin is the highest one, whereas the Fluometuron is the lowest. The properties of the prepared hydrogels may make them acceptable for practical use as bioactive controlled release matrices. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011  相似文献   

18.
BACKGROUND: Poly(N‐isopropylacrylamide) (PNIPA) nanohydrogels were synthesized by inverse microemulsion to be used for the controlled release of anti‐tumour drugs. Different methods were used to obtain drug‐loaded xerogels, and their effect on drug release was studied, and evaluated using mathematical modelling. RESULTS: Nanoparticulate hydrogels, with a z‐average diameter of 170 nm, were loaded with 5‐fluorouracil (5‐FU), methotrexate (MTX) or mitomycin C (MMC) by using spray drying (SD) and freeze drying (FD). Xerogels obtained by SD consisted of individual and independent particles, whereas particles established interactions in xerogels obtained by FD. Total drug release took place at 6 and 7 h from 5‐FU‐loaded and MMC‐loaded xerogels prepared by SD, whereas MTX was expelled from the xerogels formed using the SD process. Drug release was slower from xerogels prepared by FD: 5‐FU at 32 h, MMC at 120 h and MTX at 240 h. The Higuchi model most aptly fits the dissolution data. Non‐Fickian and Fickian release behaviour can be attributed to SD and FD formulations, respectively. CONCLUSION: The amount of drug loaded, the morphology of xerogels as well as the drug release characteristics not only depend on the drug but also mainly on the process used to obtain the drug‐loaded PNIPA xerogels. Copyright © 2008 Society of Chemical Industry  相似文献   

19.
Comb‐type graft hydrogels, composed of chitosan and poly(N‐isopropylacrylamide) (PNIPAAm), were prepared to manifest rapid temperature and pH sensitivity. Instead of directly grafting the NIPAAm monomer onto the chitosan chain, semitelechelic PNIPAAm with carboxyl end group was synthesized by radical polymerization using 3‐mercaptopropionic acid as the chain‐transfer agent, and was grafted onto chitosan having amino groups. The comb‐type hydrogels were prepared with two different graft yields and grafting regions, such as surface‐ and bulk‐grafting, and then compared with a chitosan hydrogel. The synthesis of telechelic PNIPAAm and the formation of amide group were confirmed by using FTIR spectroscopy and gel permeation chromatography. Results from the water state and thermal stability revealed that the introduction of the PNIPAAm side chain disturbed the ordered arrangement of the chitosan molecule, resulting in an increase in the equilibrium water content. Comb‐type graft hydrogels showed rapid temperature and pH sensitivity because of the free‐ended PNIPAAm attached to the chitosan main chain and the chitosan amino group itself, respectively. In particular, the surface graft hydrogel maintained its dimension at low pH, although the chitosan main chain was not crosslinked, whereas chitosan and bulk graft hydrogel were dissolved as a result of the coating effect of pH‐independent PNIPAAm. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 2612–2620, 2004  相似文献   

20.
The preparation of 5‐fluorouracil (5‐FU) loaded poly(lactic‐co‐glycolic acid) (PLGA) biodegradable nanocapsules containing magnetite nanoparticles was studied through the modified multiple emulsion solvent evaporation method for magnetically controlled delivery of anticancer drugs. The morphology and size distribution of the prepared magnetite/PLGA nanocapsules were investigated by transmission and scanning electron microscopy. The micrographs showed that the magnetic nanocapsules were almost spherical in shape and their mean diameter was in the nanometer range with a narrow size distribution. Fourier transform infrared and ultraviolet–visible spectroscopy confirmed incorporation of 5‐FU molecules into the PLGA matrix. The magnetite content was assessed by thermogravimetric and magnetometry analysis and the results showed a magnetite content of 35 wt% with high magnetic responsivity. Magnetometry measurements showed superparamagnetic properties of the magnetic nanocapsules with a saturation magnetization of 13.7 emu g?1. Such biodegradable magnetic nanocapsules could be considered as an appropriate choice for drug targeting. Furthermore, the influence of some important processing parameters such as PLGA concentration, initial loading of 5‐FU and poly(vinyl alcohol) concentration on drug content, encapsulation efficiency and in vitro drug release kinetics was investigated and optimized. The drug content and encapsulation efficiency of the magnetic nanocapsules were 4–7 wt% and 60%–80%, respectively, and the nanocapsules demonstrated controlled release of 5‐FU at 37 °C in a buffer solution. All samples exhibited a burst release at the initial stage and this burst release showed its close dependence on the formulation parameters. Copyright © 2012 Society of Chemical Industry  相似文献   

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