水凝胶角膜接触镜材料研究进展

以角膜接触镜材料的基本要求为出发点,在相关文献和专利的基础上综述了目前软性亲水的水凝胶角膜接触镜材料的研究进展及发展趋势.特别针对传统型水凝胶角膜接触镜的透氧和均一成分构建的局限,分别重点介绍了高透氧角膜接触镜材料及互穿网络角膜接触镜材料.前者通过引入硅氧烷成分使角膜接触镜的延长配戴成为可能,后者则通过交联互锁的结构实现了材料的均一性和稳定性,从而为角膜接触镜材料在药物释放和治疗用途上的更广泛应用创造了条件.     

共聚物水凝胶角膜接触镜材料的离子渗透性研究

以偶氮二异丁腈(AIBN)为引发剂,N-乙烯吡咯烷酮(NVP)单体、甲基丙烯酸-β-羟乙酯(HEMA)单体、γ-(甲基丙烯酰氧)丙基三甲氧基硅烷(KH570)单体及交联剂N,N'-亚甲基双丙烯酰胺(Bis)在一定温度下共聚制得软性角膜接触镜材料--水凝胶,并采用池膜测量法研究了钠离子在角膜接触镜材料中的渗透性能.实验发现,随NVP含量的增大,水凝胶的含水量增大,钠离子渗透性能增强;KH570含量小于15%时,钠离子渗透性能随KH570含量的增加而增强,而含量在15%～25%时钠离子渗透性能则降低;交联剂含量增大会降低钠离子的渗透性能,含量以不超过0.7%为宜.     

共聚物水凝胶接触镜材料的研究

以过氧化苯甲酰(BPO)为引发剂,N-乙烯基吡咯烷酮(NVP)、甲基丙烯酸β-羟乙酯(HEMA)以及甲基丙烯酸酯共聚,制备水凝胶接触镜材料,并研究了该水凝胶的溶胀性能。实验发现,不添加交联剂的情况下,共聚产物即可形成具有交联结构的水凝胶;随NVP含量的增大,水凝胶的平衡溶胀度也增大;少量甲基丙烯酸酯的加入,可较小幅度地降低共聚物水凝胶的平衡溶胀度;TG分析表明,NVP与HEMA二元共聚物水凝胶中的自由水容易脱水,而添加甲基丙烯酸酯可增强水凝胶的抗脱水性能,以甲基丙烯酸乙酯较为明显。     

单体组成对水凝胶接触镜材料结构的影响

以甲基丙烯酸羟乙酯(HEMA)、N乙烯吡咯烷酮(NVP)、丙烯酰胺(AM)、甲基丙烯酸甲酯(MMA)、甲基丙烯酸乙酯(EMA)或者甲基丙烯酸丁酯(BMA)为原料,采用本体共聚法制备水凝胶角膜接触镜材料。采用环境扫描电子显微镜(ESEM)研究各单体对水凝胶结构的影响,结果表明,在溶胀状态下,HEMA的均聚物水凝胶结构均匀,而HEMA与NVP共聚物水凝胶在微米层次上出现含水量不均;在脱水状态下,HEMA的均聚物以及HEMA与NVP共聚物表现出均匀的结构,HEMA与AM共聚物呈纤维状,而HEMA、NVP与MMA、EMA或者BMA共聚物均出现微米级塌缩。     

蛋白质在水凝胶角膜接触镜上的吸附及对膜渗透性能的影响

以牛血清白蛋白(BSA)为模型蛋白,通过紫外分光光度法测定了BSA在共聚物水凝胶膜材料上的吸附量．研究了泪液中蛋白质在甲基丙烯酸-β-羟乙酯和N-乙烯基吡咯烷酮(HEMA—NVP)亲水性共聚物水凝胶的吸附情况．结果表明,蛋白质的吸附量随着吸附时间的增长而增大,4天基本达到吸附平衡．蛋白质在水凝胶上的吸附量随着水凝胶的平衡含水量增大而增大,吸附的蛋白质降低了水凝胶的离子通透性和透氧性．     

角膜接触镜材料的应用和研究进展

综述了各种透明高分子材料在角膜接触镜领域的应用及其特性,指出了角膜接触镜材料存在的问题,指明了角膜接触镜材料的发展趋势.     

NVP-HEMA角膜接触镜材料的透氧性能

以过氧化二苯甲酰(BPO)为引发剂，N-乙烯基吡咯烷酮(NVP)和甲基丙烯酸β-羟乙酯(HEMA)在一定温度下共聚得水凝胶，可作为软性角膜接触镜材料．实验发现，随NVP含量的增大，水凝胶的含水量越大，透氧性增大，水凝胶材料的透氧率(Dk／L)的倒数与其厚度成正比．并自行设计了一套角膜接触镜材料透氧性能的测试装置、     

复合水凝胶角膜接触镜材料的设计与合成

通过高聚物分子设计的方法,以吸水倍率低的HEMA水凝胶为基体材料,以吸水倍率高的PVPP(交联NVP)颗粒为分散相,制备出了具有明显相界面层的复合水凝胶角膜接触镜材料.通过大量实验表明其制备工艺为:PVPP颗粒与单体HEMA的质量比为10:90,致孔剂PEG400为35%(wt,相对于总反应物),BPO为0.4%(wt,相对于反应单体),反应混合物混合均匀后立即压片、放入温度为75℃的水浴中,反应12h.为下一步研究具有药物缓释功能的、可重复利用的角膜接触镜奠定了基础.     

聚天冬氨酸交联温敏性水凝胶的药物缓释性能

选用牛血清蛋白(BSA)和5-氟尿嘧啶(5-FU)为模型药物,以聚天冬氨酸交联温敏性水凝胶为载体材料,采用包埋法制备了载药水凝胶,研究了水凝胶的载药和释药性能。水凝胶对BSA和5-FU的包埋率均大于98%。37℃时,水凝胶中丙烯酸用量越大,BSA的释放率越低;交联剂用量对BSA的释放率无显著影响。25℃时,丙烯酸用量越大,5-FU的释放率越大;交联剂用量越大,5-FU的释放率越小。37℃时,丙烯酸用量越小,5-FU的释放率越大;交联剂用量越大,5-FU的释放率越小。     

Development of ocular drug delivery systems using molecularly imprinted soft contact lenses

Recently, significant advances have been made in order to optimize drug delivery to ocular tissues. The main problems in ocular drug delivery are poor bioavailability and uncontrollable drug delivery of conventional ophthalmic preparations (e.g. eye drops). Hydrogels have been investigated since 1965 as new ocular drug delivery systems. Increase of hydrogel loading capacity, optimization of drug residence time on the ocular surface and biocompatibility with the eye tissue has been the main focus of previous studies. Molecular imprinting technology provided the opportunity to fulfill the above-mentioned objectives. Molecularly imprinted soft contact lenses (SCLs) have high potentials as novel drug delivery systems for the treatment of eye disorders. This technique is used for the preparation of polymers with specific binding sites for a template molecule. Previous studies indicated that molecular imprinting technology could be successfully applied for the preparation of SCLs as ocular drug delivery systems. Previous research, particularly in vivo studies, demonstrated that molecular imprinting is a versatile and effective method in optimizing the drug release behavior and enhancing the loading capacity of SCLs as new ocular drug delivery systems. This review highlights various potentials of molecularly imprinted contact lenses in enhancing the drug-loading capacity and controlling the drug release, compared to other ocular drug delivery systems. We have also studied the effects of contributing factors such as the type of comonomer, template/functional monomer molar ratio, crosslinker concentration in drug-loading capacity, and the release properties of molecularly imprinted hydrogels.     

环境敏感性水凝胶在药物控释系统中的应用

论述了温度敏感性水凝胶、pH敏感性水凝胶及温度/pH双重敏感性水凝胶的结构、性质及在药物控释体系中的应用.     

角膜接触透镜材料的研究进展

综述了接触透镜材料的研究进展,接触透镜从材料方面主要分为硬镜和软镜;介绍了各种透镜材料的成分、性能,并对其优缺点进行评定.聚甲基丙烯酸甲酯(PMMA)是最初的接触透镜材料,随后研制出透气性硬镜材料(RGP)以保持佩戴角膜健康.为改善佩戴舒适性,广泛研究水凝胶类软接触透镜材料,主要有聚甲基丙烯酸β-羟乙酯(HEMA)、聚乙烯吡咯烷酮(PVP)和聚乙烯醇(PVA)等材料;为提高软镜的透氧性等性能,目前研究的热点是高透氧性软接触透镜材料,主要以有机硅、有机氟等大分子单体合成水凝胶材料,以及生物改性的软镜材料.     

Evaluation of superabsorbent linseed-polysaccharides as a novel stimuli-responsive oral sustained release drug delivery system

Context: Advancement in technology has transformed the conventional dosage forms to intelligent drug delivery systems. Such systems are helpful for targeted and efficient drug delivery with minimum side effects. Drug release from these systems is governed and controlled by external stimuli (pH, enzymes, ions, glucose, etc.). Polymeric biomaterial having stimuli-responsive properties has opened a new area in drug delivery approach.

Objective: Potential of a polysaccharide (rhamnogalacturonan)-based hydrogel from Linseeds (Linum usitatissimum L.) was investigated as an intelligent drug delivery material.

Materials and methods: Different concentrations of Linseed hydrogel (LSH) were used to prepare caffeine and diacerein tablets and further investigated for pH and salt solution-responsive swelling, pH-dependent drug release, and release kinetics. Morphology of tablets was observed using SEM.

Results: LSH tablets exhibited dynamic swelling–deswelling behavior with tendency to swell at pH 7.4 and in deionized water while deswell at pH 1.2, in normal saline and ethanol. Consequently, pH controlled release of the drugs was observed from tablets with lower release (<10%) at pH 1.2 and higher release at pH 6.8 and 7.4. SEM showed elongated channels in swollen then freeze-dried tablets.

Discussion: The drug release was greatly influenced by the amount of LSH in the tablets. Drug release from LSH tablets was governed by the non-Fickian diffusion.

Conclusions: These finding indicates that LSH holds potential to be developed as sustained release material for tablet.     

Investigation of charge effects on drug release behavior for ionic thermosensitive hydrogels

The influence of various drugs with different charges on the drug release behavior in porous ionic thermosensitive hydrogels was investigated. The present hydrogels were prepared from N-isopropylacrylamide (NIPAAm) and cationic monomer, trimethyl (acrylamido propyl) ammonium iodide (TMAAI), or anionic monomer, acrylic acid (AA), or zwitterionic monomer, N′,N′-dimethyl (acrylamido propyl) ammonium propane sulfonate (DMAAPS), or nonionic monomer, poly(ethylene glycol) methylether acrylate (PEGMEA), and pore-forming agent, poly(ethylene glycol) (PEG) with different molecular weights. Caffeine as a nonionic drug, crystal violet (CV) as a cationic drug solute, and phenol red as an anionic drug solute were chosen as model drugs to perform the drug release experiment. Results show that the release ratio of caffeine in the hydrogels is not affected by the ionicity of hydrogels. The CV strongly interacted with the anionic hydrogel; thus, the CV release ratio is very low. CV is only adsorbed on the skin layer of the cationic hydrogel due to charge repulsion and is released rapidly. The result of phenol red (anionic solute) release in the hydrogels is contrary to CV. In addition, the partition coefficients (K_d) and the drug delivery behavior of the present gels were also investigated.     

半纤维素基水凝胶制备及应用研究进展

半纤维素基水凝胶是一种具有优异保水性、良好生物相容性和力学性能的三维网络状亲水聚合物,在软材料领域尤其是半纤维素基材料研究领域备受瞩目。本文综述了近年来半纤维素基水凝胶的研究进展,从化学交联和物理交联两个方面介绍了半纤维素基水凝胶的制备方法、形成机理和性能,比较了化学交联中光、酶、微波辐射和辉光放电电解等离子体等不同引发体系的差异,总结了半纤维素基水凝胶在药物控释、伤口敷料、高效吸附及3D打印等领域的最新应用和发展,并对半纤维素基水凝胶领域所面临的挑战进行了总结和展望,以期为新型半纤维素水凝胶的研究提供参考。     

Design of polymeric nanoparticles and its applications as drug delivery systems for acne treatment

Objective: The aim of this study was to evaluate a formulation made of poly(lactide-co-glycolide) (PLGA) nanoparticles containing azelaic acid for potential acne treatment.

Methods: Azelaic acid-loaded PLGA nanoparticles were prepared by spontaneous emulsification processes using poloxamer 188 as stabilizer. Several manufacturing parameters such as stirring rate, concentration of stabilizer and different recovery methods were investigated. Nanoparticles were evaluated in terms of size, zeta potential, encapsulation efficiency, release kinetics and permeation kinetics in vitro. Furthermore, in vitro toxicological studies were performed in Saccharomyces cerevisiae model.

Results: The results showed that by adjusting some formulation conditions it was possible to obtain nanoparticles with high loading and a controlled drug release. Freeze-dried recovery altered the nanoparticles structure by enhancing porous structures and mannitol was required to control the mean particle size. The centrifugation recovery was found to be the best approach to nanoparticles recovery. Similar toxicity profiles were observed for both drug-free and azelaic acid-loaded nanoparticles, with concentration-dependent decreases in cell viability.

Conclusion: These results indicate a potential formulation for controlled release delivery of azelaic acid to the follicular unit.     

自修复氧化海藻酸钠-羧甲基壳聚糖水凝胶的制备及药物缓释性能

本研究基于动态亚胺键合成了一种具有自修复性能的氧化海藻酸钠-羧甲基壳聚糖水凝胶(OSA-CMCS).通过海藻酸钠的糖醛酸,合成了OSA,并通过与CMCS的席夫碱反应制备了具有不同交联度的自修复OSA-CMCS水凝胶,研究了OSA-CMCS水凝胶的微观形态、黏弹性能、溶胀性能、自修复性能、酶促降解性能和体外药物释放性能....     

Development and in vitro characterization of chitosan-coated polymeric nanoparticles for oral delivery and sustained release of the immunosuppressant drug mycophenolate mofetil

Objective: To develop an oral sustained release formulation of mycophenolate mofetil (MMF) for once-daily dosing, using chitosan-coated polylactic acid (PLA) or poly(lactic-co-glycolic) acid (PLGA) nanoparticles. The role of polymer molecular weight (MW) and drug to polymer ratio in encapsulation efficiency (EE) and release from the nanoparticles was explored in vitro.

Methods: Nanoparticles were prepared by a single emulsion solvent evaporation method where MMF was encapsulated with PLGA or PLA at various polymer MW and drug: polymer ratios. Subsequently, chitosan was added to create coated cationic particles, also at several chitosan MW grades and drug: polymer ratios. All the formulations were evaluated for mean diameter and polydispersity, EE as well as in vitro drug release. Differential scanning calorimetry (DSC), surface morphology, and in vitro mucin binding of the nanoparticles were performed for further characterization.

Results: Two lead formulations comprise MMF: high MW, PLA: medium MW chitosan 1:7:7 (w/w/w), and MMF: high MW, PLGA: high MW chitosan 1:7:7 (w/w/w), which had high EE (94.34% and 75.44%, respectively) and sustained drug release over 12?h with a minimal burst phase. DSC experiments revealed an amorphous form of MMF in the nanoparticle formulations. The surface morphology of the MMF NP showed spherical nanoparticles with minimal visible porosity. The potential for mucoadhesiveness was assessed by changes in zeta potential after incubation of the nanoparticles in mucin.

Conclusion: Two chitosan-coated nanoparticles formulations of MMF had high EE and a desirable sustained drug release profile in the effort to design a once-daily dosage form for MMF.