Photopolymerized hydrogel composites from poly(ethylene glycol) and hydroxyapatite for controlled protein delivery in vitro

The incorporation of hard particles into soft hydrogels can improve the mechanical properties and provide necessary bioactivity to the hydrogels for desired biomedical applications. Hydrogel composites containing hydroxyapatite (HA) are promising materials for orthopedic applications. In this study, injectable poly(ethylene glycol) (PEG) hydrogel precursor solutions containing HA particles and model protein bovine serum albumin (BSA) were synthesized in situ by photopolymerization. In vitro BSA release properties from the hydrogel composites containing various amounts of HA were investigated and discussed. Fourier transform infrared spectroscopy and scanning electron microscopy were employed to investigate the interaction between HA and the hydrogel network and the morphology of the hydrogel composites. It is found that PEG hydrogel composites containing HA sustained the release of BSA for at least 5 days and the presence of HA slowed down BSA release. Photopolymerized hydrogel composites containing HA may find potential use as a drug delivery matrix for orthopedic tissue engineering. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Enhancement of fibroblastic proliferation from photoreactive starch with immobilized epidermal growth factor

Carboxymethyl starch was modified by the incorporation of an azidophenyl group to prepare photoreactive starch, and characterized by Fourier transform infrared reflectance (FT‐IR), proton nuclear magnetic resonance (¹H‐NMR), and ultraviolet (UV) spectroscopy. Photo‐irradiation immobilized the Az‐starch on a polystyrene plate and it was stably retained on the surface. The protein containing immobilized Az‐starch was also immobilized on a stripe micropatterned plate. UV irradiation time and Az‐starch concentration were used to alter the physical properties of Az‐starch and consequently control the rate of epidermal growth factor (EGF) release. The Az‐starch that released growth factor was not cytotoxic to 3T3‐L1 fibroblast cells, and the immobilized EGF maintained its activity and induced cellular proliferation in vitro. These results suggest that Az‐starch could be useful as a clinical synthetic material for medical applications. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

阿司匹林壳聚糖-明胶载药微胶囊的制备及性能研究

以阿司匹林为囊芯,壳聚糖和明胶为壁材,采用乳化交联法制备了明胶-壳聚糖微胶囊,考察了芯壁比、水油体积比、乳化剂用量、交联时间等因素对微胶囊性能的影响.采用高效液相色谱法来测定微胶囊的载药量、包封率和释放性能.研究发现,当芯壁比为1∶1,水油体积比为1∶3,乳化剂Span-80用量为5％,交联时间为2h的条件下制备的微胶囊形状规整,载药量为47.99％,包封率为83.18％,且在人工肠液中具有明显的缓释效果.     

囊泡的制备与应用研究进展

囊泡是表面活性剂溶液中的一种特异聚集形态,它可以通过表面活性剂的复配形成,也可以在生物体内自发的形成.囊泡的微小尺寸和多层结构为纳米材料开发以及生物膜研究提供一种途径,因此受到科研人员的广泛关注.文章综述了囊泡的形成及其在医药和纳米粒子制备方面的应用.     

聚乙二醇在药物载体应用中的优缺点

聚乙二醇在基于聚合物的药物传递系统中是最常用的高分子同时也是隐形高分子的金标准.从第一个PEG化的产品上市到目前为止,人们获得了大量关于这种聚合物的临床经验-不仪有它的优点,而且也有潜在的副作用以及并发症.文章列举了PEG在生物医药领域应用的一系列优良性质和引起的毒副作用.     

Challenges in nucleic acid‐lipid films for transfection

The use of surface‐based methods for the delivery of therapeutics has recently generated increasing interest. These platforms have tremendous potential to minimize detrimental side effects associated with systemic delivery by localizing the therapeutic vehicle, and thus provide higher local doses for improved efficacy. Cationic lipids are one of the most commonly used synthetic carriers for the delivery of genetic cargo, such as DNA and RNA. However, reports on the use of lipid‐based films for gene delivery are scarce. Here we investigate the use of a lipid‐based film for the in vitro delivery of plasmid DNA. Solid DNA‐lipid films show very low levels of transfection, while identical complexes prepared for bolus delivery provide high levels of transfection when used directly. We investigate the mechanism, whereby the activity of these solid‐state films is lost and suggest methods for circumventing these challenges and restoring the efficacy of these films as gene delivery platforms. © 2013 American Institute of Chemical Engineers AIChE J, 59: 3203–3213, 2013     

Adsorption and drug release based on β‐cyclodextrin‐grafted hydroxyapatite composite

In this study, β‐cyclodextrin (β‐CD) was covalently grafted on hydroxyapatite (HA) using a coupling agent to improve the drug loading capacity and prolong the drug release. The binding of β‐CD on the HA surface was confirmed by Fourier transformation infrared spectroscopy, thermal gravimetric analysis, and X‐ray powder diffraction. The adsorption capacity of ofloxacin on β‐CD‐grafted hydroxyapatite (β‐CD‐g‐HA) composite was found to be 30 mg g^?1 at 37°C and 24 h. The adsorption process is spontaneous, given the negative values of free energy change. Compared with the release of ofloxacin loaded on HA, the release of ofloxacin loaded on β‐CD‐g‐HA was slowed down 28% and 21% in pH 2.0 and pH 7.4 buffer media at 2 h, respectively. Biocompatibility of β‐CD‐g‐HA was assessed by MTT assay, and the result showed that it had no cytotoxicity. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Preparation and characterization of biodegradable poly(sebacic anhydride) chain extended by glycol as drug carrier

Glycol modified poly(sebacic anhydride) (PSA), a biodegradable poly(ester anhydride) copolymer, was prepared by melt bulk reaction of PSA and glycol. The structure of PSAG was characterized by FTIR, ¹H NMR, and GPC. The results indicate the formation of ester bonds along the polyanhydride backbone. The thermal properties and crystallinity changes of the polyanhydrides were investigated using DSC and XRD. In vitro degradation experiments show that the degradation rate of PSAG is slower than that of PSA because of the introduction of the glycol. Using dexamethasone as a model drug, the in vitro release rate of a drug from PSAG discs was shown to be slower than that from PSA discs, and no initial burst releases were observed for 13 days. PSAG is therefore a promising candidate, which control the release of an incorporated drug over a sustained period of time. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Compression molding of biodegradable drug‐eluting implants for sustained release of metronidazole and doxycycline

The purpose of this report was to develop solvent‐free biodegradable drug‐eluting implants that provide sustained release of metronidazole and doxycycline. The drug‐eluting implants were prepared using the compression molding technique. To fabricate the implants, polylactide‐polyglycolide copolymers were premixed with metronidazole or doxycycline. The mixture was then compression molded and sintered to form implants of various sizes and geometries. An elution method and an HPLC assay were used to characterize the in vitro release rates of the antibiotics over a 28‐day period. A bacterial inhibition test was also carried out to determine the bioactivity of released antibiotics. The concentrations of both metronidazole and doxycycline were much greater than the minimum inhibitory concentration of Escherichia coli for up to 3 and 4 weeks, respectively, and the bioactivities of the antibiotics remained high after the fabrication process. Furthermore, the initial burst could be minimized and the release rate could be reduced by increasing the size of the implants and by adopting low drug to polymer ratios. By using this compression molding technique and appropriate processing parameters, we will be able to fabricate biodegradable implants of various types of antibacterial drugs for long‐term local deliveries. Eventually, biodegradable drug‐eluting implants may be used to treat various periodontal diseases. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Skin permeation of buflomedil form adhesive matrix patches

The main objective of this research work was to fabricate and evaluate adhesive matrix-type transdermal patches of buflomedil hydrochloride, employing different ratios of pressure sensitive adhesives (PSAs) by solvent casting technique. The adhesive matrix-type transdermal patches were evaluated by their in vitro physicochemical properties such as thickness, moisture content, weight variation, drug content uniformity, etc. The effects of PSAs ratio, drug loading, and concentration of permeation enhancer were evaluated thoroughly. Ex vivo skin permeation studies with kinetic modeling of adhesive matrix patches were systematically evaluated. Based on the above observations, the best optimized buflomedil hydrochloride-loaded adhesive matrix-type transdermal patch was further characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction study, and differential scanning calorimetry analyses. Drug containing adhesive matrix patches showed sustained release property without showing any incompatibility in adhesive matrix system. Hence, adhesive matrix-type transdermal patches of buflomedil hydrochloride can be used as a potential carrier for sustained transdermal delivery of hydrophilic drugs like buflomedil hydrochloride.