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In the present research, a type of imprinted hydrogels, in which 5-fluorouracil is complexed non-covalently to the monomers and cross-linked into the hydrogel matrix, is synthesized in order to evaluate the possibility of their applications in sustaining the release of 5-fluorouracil due to the drug’s heightened interactions with the imprinted binding sites. Because of the hydrophility, hydrogels can absorb large amounts of water. As a result, drug release mechanisms are different from hydrophobic polymers. Mathematical model has been established to predict the drug release from the hydrogel matrix as a function of time. The drug release mechanism when immersed in release medium is discussed based on mathematical analysis. Swelling studies are performed and the capability of the hydrogels to reload 5-fluorouracil in aqueous solutions is evaluated. In vitro release studies after reloading are conducted. Mathematical analysis suggest that drug release kinetics from the hydrogels fit Fickian mechanism, further evaluation of the fitness for different hydrogel types reveal that the conformation of binding sites can play a very important role in deciding the kind of drug release mechanism. Experiments reveal that all hydrogels show swelling property. The imprinted hydrogels bind much more 5-fluorouracil than non-imprinted ones, and they sustain 5-fluorouracil release better than non-imprinted hydrogels. This research indicates that the imprinted hydrogels would be a potential promising device for drug delivery. 相似文献
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《Journal of Saudi Chemical Society》2022,26(6):101541
This research aims to fabricate and characterize chemically crosslinked CMC/PVP-co-poly (AMPS) based hydrogel for the sustained release of model drug metoprolol tartrate through the free radical polymerization technique. Box-Behnken Design was used to optimize CMC/PVP-co-poly (AMPS) hydrogel by varying the content of reactants such as; polymers (CMC and PVP), monomer (AMPS), and crosslinker (EGDMA). Carboxymethyl cellulose (CMC) was crosslinked chemically with AMPS with a constant ratio of PVP by the ethylene glycol dimethacrylate as the crosslinker in the presence of sodium hydrogen sulfite (SHS)/ammonium peroxodisulfate (APS) as initiators. After developing CMC-based hydrogels using different polymers, monomer, and crosslinker concentrations, this study encompassed dynamic swelling, sol–gel fraction, drug release and chemical characterizations such as FTIR, XRD, TGA, DSC, and SEM. In vitro drug release and swelling were performed at 1.2 and 6.8 pH to determine the sustained release pattern and pH-responsive behavior. These parameters depended on the crosslinker, polymer, and monomer ratios used in the formulation development. XRD, SEM, and FTIR showed the successful grafting of constituents resulting in the formation of a stable hydrogel. DSC and TGA confirmed the thermodynamic stability of the hydrogel. Hydrogel swelling was increased with an increase in the ratio of monomer; however, an increase in the ratio of polymer and crosslinker decreased the hydrogel swelling. In vitro gel fraction and drug release also depended on polymer, monomer, and crosslinker ratios. The fabricated CMC/PVP-co-poly (AMPS) hydrogels constituted a potential system for sustained drug delivery. 相似文献
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Jae Hyung Park Yong Woo Cho Yoen Ju Son Kwangmeyung Kim Hesson Chung Seo Young Jeong Kuiwon Choi Chong Rae Park Rang-Woon Park In-San Kim Ick Chan Kwon 《Colloid and polymer science》2006,284(7):763-770
An anthracycline drug, adriamycin, was chemically conjugated onto the backbone of glycol chitosan via an acid-labile cis-aconityl linkage. The physicochemical characteristics of the glycol chitosan–adriamycin (GC–ADR) conjugates were investigated by dynamic light scattering, atomic force microscopy, and fluorescence spectroscopy. The GC–ADR conjugates were capable of forming nano-sized self-aggregates in an aqueous medium, when the adriamycin content in the conjugate was in the range of 2.0–5.0 wt.%. The self-aggregates were spherical in shape, and had mean diameters of 238–304 nm, depending on the adriamycin content. The critical aggregation concentrations of the conjugates, estimated by the fluorescence quenching method, were as low as 1.0–2.5×10−2 mg/ml. The size of self-aggregates was not affected by the polymer concentration in the range from 50 to 2,000 μg/ml, and was maintained up to 8 days in phosphate-buffered saline (pH 7.4), indicating high colloidal stability. The release of adriamycin from self-aggregates was significantly dependent on the pH of the medium due to the cis-aconityl linkage; e.g., the amount of adriamycin released for 4 days was 7.3±0.3% at pH 7, whereas it was 29.3±1.9% at pH 4. The cell viability results demonstrated that free adriamycin shows more potent cytotoxicity than the conjugates, primarily attributed to the sustained release of adriamycin from self-aggregates. In conclusion, the self-aggregates, formed by GC–ADR conjugates, might be useful for the site-specific delivery of adriamycin in a sustained manner. 相似文献
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采用Gadelle-Defaye法制备了全-6-氨基-β-环糊精[β-CD-(NH2)7],并用"Grafting-from"接枝法得到不同分子量的星型结构β-环糊精-g-聚L-谷氨酸(β-CD-g-PLGA).对β-CD-g-PLGA进行酰肼化改性后与醛基化海藻酸钠(ALG-CHO)通过席夫碱交联反应制备β-CD-g-PLGA/ALG水凝胶.研究了前驱体浓度以及β-CD-gPLGA分子量对β-CD-g-PLGA/ALG水凝胶性能的影响,并以疏水性辛伐他汀(SIM)为模型药物,研究了水凝胶对SIM的控制释放行为. 相似文献
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Kamal Barley Alhaji Cherif 《Applied mathematics and computation》2011,217(13):6273-6281
Current theories from biosocial (e.g., the role of neurotransmitters in behavioral features), ecological (e.g., cultural, political, and institutional conditions), and interpersonal (e.g., attachment) perspectives have grounded interpersonal and romantic relationships in normative social experiences. However, these theories have not been developed to the point of providing a solid theoretical understanding of the dynamics present in interpersonal and romantic relationships, and integrative theories are still lacking. In this paper, mathematical models are used to investigate the dynamics of interpersonal and romantic relationships, via ordinary and stochastic differential equations, in order to provide insight into the behaviors of love. The analysis starts with a deterministic model and progresses to nonlinear stochastic models capturing the stochastic rates and factors (e.g., ecological factors, such as historical, cultural and community conditions) that affect proximal experiences and shape the patterns of relationship. Numerical examples are given to illustrate various dynamics of interpersonal and romantic behaviors with particular emphases placed on sustained oscillations and transitions between locally stable equilibria that are observable in stochastic models (closely related to real interpersonal dynamics), but absent in deterministic models. 相似文献
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Biodegradable plastics are an interesting class of drug carriers for controlled release, as they can decompose to nontoxic, readily bioresorbable products and are advantageous over conventional biomaterials because they do not require surgical retrieval from the body after completion of treatment. In this work, films of poly(d,l-lactic acid) (d,l-PLA) were deposited by the solvent casting technique, onto the surfaces of stainless steel plates and their biodegradation was studied after immersion in buffer solutions. The release of two model drugs, i.e. guaifenesin and ipriflavone, from the above d,l-PLA systems loaded with these compounds at various concentrations, was also studied.The experimental results showed that for low drug concentrations, the release of guaifenesin is controlled by the biodegradation rate of PLA, whereas for high concentrations the burst effect becomes the dominant release mechanism. The rate of release is faster at low pH values probably due to an acceleration of PLA biodegradation, whereas there are no chemical interactions between drug and polymer, that could essentially influence the release rate of the drug or the biodegradation of the polymer. On the other hand, high guaifenesin concentrations produce increased porosity in the PLA matrix and seem to accelerate its biodegradation and further the drug release rate. Finally, the release of ipriflavone in a mixture of 2-propanol/water is clearly a two stage process and, again, the burst effect seems to control the delivery process at high drug concentration.In conclusion, the present study shows that similar results to those obtained with d,l-PLA tablets loaded with model drugs can be obtained with thin coatings of the same systems. This might be of interest for transfer of the existing knowledge to the design of biomedical implants, treated with coatings of d,l-PLA containing reactive compounds. 相似文献
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Controlled release properties of Chitosan encapsulated volatile Citronella Oil microcapsules by thermal treatments 总被引:9,自引:0,他引:9
This research uses modified orifice method to prepare the O/W type Chitosan encapsulated volatile Citronella Oil microcapsules. In this article, we investigated the forming condition of microcapsules and the influence to sustained release effect of volatile Citronella Oil by applying thermal pretreatment to microcapsules. The results suggest that the forming of microcapsules should be processed under the fundamental conditions of: (1) the concentration of Chitosan is at least 0.2 wt%, (2) NaOH is greater than 0.1 wt%, and (3) with the additive of coconut oil as natural surfactant, so that we could obtain final product of microcapsules with better formation and dispersion. The changes in concentration of Chitosan will affect the encapsulation efficiency of the volatile Citronella Oil. When the concentrations of Chitosan are 0.5%, 1.0% and 1.5%, the encapsulation efficiencies are 98.2%, 95.8% and 94.7%, respectively. The particle size of Chitosan microcapsules would decrease as the emulsification stirring speed increases. When the stirring speeds are 400 rpm, 800 rpm, and 1500 rpm, the average particle sizes of microcapsules produced are 225 ± 24 μm, 131 ± 20 μm, and 11 ± 3 μm, respectively. If the microcapsules were thermal pretreated at 80 °C, the structure of Chitosan wall membrane would shrink and thus achieve the effect of sustained release. The sustaining effect would increase along with treatment time increases. 相似文献
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利用静电纺丝法制备了聚丁二酸丁二醇酯(PBS)纳米纤维膜及PBS和富血小板血浆(PRP)的混合纳米纤维膜. 通过扫描电子显微镜、 3-(4,5-二甲基噻唑-2)-2,5-二苯基四氮唑溴盐(MTT)比色法、 支架表面细胞荧光染色法、 材料溶血行为及Elisa法检测体外释放综合评价了支架材料的性能及生物活性. 结果表明, 纳米纤维膜对人骨肉瘤细胞系MG63细胞增殖具有促进作用; 生长因子在最初的突释后, 随材料降解而缓释; 支架材料溶血率为0.1475%(<5%), 符合医用材料的溶血实验要求. 相似文献