Enhanced biocompatibility and antibacterial property of polyurethane materials modified with citric acid and chitosan

Citric acid (CA) and chitosan (CS) were covalently immobilized on polyurethane (PU) materials to improve the biocompatibility and antibacterial property. The polyurethane pre-polymer with isocyanate group was synthesized by one pot method, and then grafted with citric acid, followed by blending with polyethersulfone (PES) to prepare the blend membrane by phase-inversion method so that chitosan can be grafted from the membrane via esterification and acylation reactions eventually. The native and modified membranes were characterized by attenuated total reflectance-Fourier transform infrared spectroscope, X-ray photoelectron spectroscopy, scanning electron microscopy, water contact angle measurement, and tensile strength test. Protein adsorption, platelet adhesion, hemolysis assay, activated partial thromboplastin time, prothrombin time, thrombin time, and adsorption of Ca²⁺ were executed to evaluate the blood compatibility of the membranes decorated by CA and CS. Particularly, the antibacterial activities on the modified membranes were evaluated based on a vitro antibacterial test. It could be concluded that the modified membrane had good anticoagulant property and antibacterial property.     

Glutathione-dependent micelles based on carboxymethyl chitosan for delivery of doxorubicin

Novel glutathione (GSH)-dependent micelles based on carboxymethyl chitosan (CMCS) were developed for triggered intracellular release of doxorubicin (DOX). DOX-33′-Dithiobis (N-hydroxysuccinimidyl propionate)-CMCS (DOX-DSP-CMCS) prodrugs were synthesized. DOX was attached to the amino group on CMCS via disulfide bonds and drug-loaded micelles were formed by self-assembly. The micelles formed core–shell structure with CMCS and DOX as the shell and core, respectively, in aqueous media. The structure of the prodrugs was confirmed by IR and proton nuclear magnetic resonance (¹H NMR) spectroscopy. The drug-loading capacity determined by UV spectrophotometry was 4.96% and the critical micelle concentration of polymer prodrugs determined by pyrene fluorescence was 0.089 mg/mL. Micelles were spherical and the mean size of the nanoparticles was 174 nm, with a narrow polydispersity index of 0.106. Moreover, in vitro drug release experiments showed that the micelles were highly GSH-sensitive owing to the reductively degradable disulfide bonds. Cell counting kit (CCK-8) assays revealed that DOX-DSP-CMCS micelles exhibited effective cytotoxicity against HeLa cells. Moreover, confocal laser scanning microscopy (CLSM) demonstrated that DOX-DSP-CMCS micelles could efficiently deliver and release DOX in the cancer cells. In conclusion, the DOX-DSP-CMCS nanosystem is a promising drug delivery vehicle for cancer therapy.     

壳聚糖定量分析方法的研究进展

壳聚糖(chitosan)是目前自然界唯一带阳离子的碱性多糖,具有减肥降脂、增强免疫力等生物活性,使其在医药和功能性食品领域都备受关注,因此,以壳聚糖为核心成分的产品质量控制是一个重要的研究课题.本文综述了近年来壳聚糖定量分析的主要方法,包括光谱法、电化学法和高效液相色谱法等,并对其分析测定的发展进行展望,旨在为各类产品中壳聚糖的定量分析提供新的思路.     

On the Production of Chitosan-Coated Polycaprolactone Nanoparticles in a Confined Impinging Jet Reactor

This work is focused on the synthesis of polycaprolactone nanoparticles, coated with chitosan, in a confined impinging jet reactor using the solvent displacement method. The role of the various reacting species was investigated, evidencing that a biocompatible polymer, for example, polycaprolactone, is required to support chitosan to obtain a monomodal particle size distribution, with low particle diameters. A surfactant is required to reduce the nanoparticle size (down to a mean diameter of about 260 nm) and obtain a positive zeta potential (about +31 mV), perfectly suitable for pharmaceutical applications. Different surfactants were tested, and Poloxamer 388 appeared to be preferable to polyvinyl alcohol. The effect of the concentration of Poloxamer 388 (in the range 0.5-5 mg mL^?1) and of chitosan (in the range 1.5-5 mg mL^?1) on both the mean particle size and zeta potential was also investigated, evidencing that chitosan concentration has the strongest effect on both parameters. Finally, the effect of solvent evaporation, quenching and feed flow rate was investigated, showing that the evaporation stage does not affect particle characteristics, quenching is required to avoid particle aggregation, and a minimum liquid flow rate of 80 mL min^?1 is required in the considered reactor to minimize the particle size.     

D-Optimal Design in the Development of Rheologically Improved In Situ Forming Ophthalmic Gel

In situ forming ophthalmic gels need to be fine tuned considering all the biopharmaceutical challenges of the front of the eye in order to increase drug residence time at the application site resulting in its improved bioavailability and efficacy. The aim of this study was to develop in situ forming ophthalmic poloxamer P407/poloxamer P188/chitosan gel fine tuned in terms of polymer content, temperature of gelation, and viscosity. Minimizing the total polymer content while retaining the advantageous rheological properties has been achieved by means of D-optimal statistical design. The optimal in situ forming gel was selected based on minimal polymer content (P407, P188, and chitosan concentration of 14.2%, 1.7%, and 0.25% w/w, respectively), favorable rheological characteristics, and in vitro resistance to tear dilution. The optimal in situ forming gel was proved to be robust against entrapment of active pharmaceutical ingredients making it a suitable platform for ophthalmic delivery of active pharmaceutical ingredients with diverse physicochemical properties.     

聚己内酯/海藻酸钠/壳聚糖材料制备 组织工程椎间盘双相支架

摘要：目的 以聚己内酯（PCL）、海藻酸钠、壳聚糖为材料,研制椎间盘双相支架,并评估其作为组织工程椎间盘 的可行性。方法 聚己内酯作为原料,采用熔融电纺法制备取向性多孔纤维环支架,将海藻酸钠/壳聚糖水凝胶注入 到中空的纤维环（AF）支架中央合成双相椎间盘支架。通过体式显微镜、扫描电镜观测双相支架的结构、孔径、孔隙 率;人脐带干细胞复合双相支架体外培养7 d,用死活细胞染色法评价生物相容性,CCK-8实验测定细胞增殖情况,力 学加载仪器测量双相支架的压缩弹性模量。结果 体式显微镜和扫描电镜可见纤维环相成菱形多孔结构,髓核相 （NP）呈不规则多孔结构;纤维环相和髓核相孔径分别为（225.6±3.9）μm、（205.5±5.2）μm,孔隙率分别为（74.17± 0.39）%、（85.52±0.48）%,支架扫描电镜可见细胞黏附在支架表面,周围有细胞外基质分泌;死活细胞染色显示无死 细胞;CCK-8检测结果显示人脐带干细胞具有良好的增殖活性,压缩弹性模量（173.24±44.93）kPa。结论 以聚己内 酯、海藻酸钠、壳聚糖为材料制备的椎间盘双相支架,具有良好的孔径、孔隙率和细胞相容性,支架间结合紧密,具有 三维网络结构,优良的力学特性,是构建组织工程椎间盘理想载体。     

Neuroprotective effect of gold nanoparticles composites in Parkinson's disease model

Parkinson’s disease (PD) is second most common neurodegenerative disorder worldwide. Although drugs and surgery can relieve the symptoms of PD, these therapies are incapable of fundamentally treating the disease. For PD patients, over-expression of α-synuclein (SNCA) leads to the death of dopaminergic neurons. This process can be prevented by suppressing SNCA over-expression through RNA interference. Here, we successfully synthesized gold nanoparticles (GNP) composites (CTS@GNP-pDNA-NGF) via the combination of electrostatic adsorption and photochemical immobilization, which could load plasmid DNA (pDNA) and target specific cell types. GNP was transfected into cells via endocytosis to inhibiting the apoptosis of PC12 cells and dopaminergic neurons. Simultaneously, GNP composites are also used in PD models in vivo, and it can successfully cross the blood-brain barrier by contents of GNP in the mice brain. In general, all the works demonstrated that GNP composites have good therapeutic effects for PD models in vitro and in vivo.     

中心组合设计法优化载基因壳聚糖纳米粒的最佳转染制备区域

目的：采用中心组合设计法优化载基因壳聚糖纳米粒的最佳转染制备区域。方法采用复凝聚法制备载质粒基因的壳聚糖纳米粒,选择壳聚糖浓度和质粒基因浓度作为实验考察因素,应用两因素五水平中心组合设计优化最佳转染制备区域,优化指标选择平均粒径和基因转染率。通过透射电镜观察纳米粒的形态;通过动态光散射和电泳光散射技术分别测量纳米粒的粒径和Zeta电位;通过凝胶电泳分析考察质粒在纳米粒制备过程中的稳定性;通过倒置荧光显微镜观察质粒基因在细胞内的表达;通过流式细胞技术测定纳米粒的转染效率。结果成功优化了载基因壳聚糖纳米粒的最佳转染制备区域。优选条件下制备的纳米粒大多呈球形,纳米粒平均粒径为217．6 nm,粒径多分散系数为0．241,表明粒径分布较窄。纳米粒zeta电位为＋22．4 mV,表明纳米粒表面带有正电荷,可以增加纳米粒混悬液的稳定性。凝胶电泳分析结果表明质粒基因在纳米粒制备过程中没有遭到破坏。纳米粒的细胞转染效率比较高,能够高效地将绿色荧光蛋白质粒基因递送到细胞内,并且基因表达产生绿色荧光蛋白。结论本研究建立的数学模型具有良好的预测性。在优化的制备区域内制备的载基因壳聚糖纳米粒的转染性能比较理想。     

Chitosan/Silver Nanoparticle/Graphene Oxide Nanocomposites with Multi-Drug Release,Antimicrobial, and Photothermal Conversion Functions

In this work, we designed and fabricated a multifunctional nanocomposite system that consists of chitosan, raspberry-like silver nanoparticles, and graphene oxide. The room temperature atmospheric pressure microplasma (RT-APM) process provides a rapid, facile, and environmentally-friendly method for introducing silver nanoparticles into the composite system. Our composite can achieve a pH controlled single and/or dual drug release. Under pH 7.4 for methyl blue loaded on chitosan, the drug release profile features a burst release during the first 10 h, followed by a more stabilized release of 70–80% after 40–50 h. For fluorescein sodium loaded on graphene oxide, the drug release only reached 45% towards the end of 240 h. When the composite acted as a dual drug release system, the interaction of fluorescein sodium and methyl blue slowed down the methyl blue release rate. Under pH 4, both single and dual drug systems showed a much higher release rate. In addition, our composite system demonstrated strong antibacterial abilities against E. coli and S. aureus, as well as an excellent photothermal conversion effect under irradiation of near infrared lasers. The photothermal conversion efficiency can be controlled by the laser power. These unique functionalities of our nanocomposite point to its potential application in multiple areas, such as multimodal therapeutics in healthcare, water treatment, and anti-microbials, among others.     

The Preparation and Characterization of Chitosan-Based Hydrogels Cross-Linked by Glyoxal

In this study, hydrogels based on chitosan cross-linked by glyoxal have been investigated for potential medical applications. Hydrogels were loaded with tannic acid at different concentrations. The thermal stability and the polyphenol-releasing rate were determined. For a preliminary assessment of the clinical usefulness of the hydrogels, they were examined for blood compatibility and in the culture of human dental pulp cells (hDPC). The results showed that after immersion in a polyphenol solution, chitosan/glyoxal hydrogels remain nonhemolytic for erythrocytes, and we also did not observe the cytotoxic effect of hydrogels immersed in tannic acid (TA) solutions with different concentration. Tannic acid was successfully released from hydrogels, and its addition improved material thermal stability. Thus, the current findings open the possibility to consider such hydrogels in clinics.