Photo cross-linked biodegradable hydrogels for enhanced vancomycin loading and sustained release

A series of biodegradable hydrogels based on dextran and poly（L-glutamic acid） were fabricated for effective vancomycin loading and release. The preparation of hydrogels was simply achieved by photo cross-linking of methacrylated dextran and poly（L-glutamic acid）-g-hydroxyethyl methacrylate （PGH） in the presence of photoinitiator 12959. The structures of hydrogels were characterized by FTIR and SEM. The swelling and enzymatic degradation behaviors of hydrogels were examined to be dependent on the poly（L-glutamic acid） content in the hydrogels. The higher content of poly（L-glutamic acid） in the gel, the higher swelling ratio and quicker degradation were observed. More interestingly, the hydrogel with higher PGH ratio showed higher vancomycin （VCM） loading content, which might be due to the electrostatic interaction between carboxylate groups in hydrogel and ammonium group of VCM. In vitro drug release from the VCM-loaded hydrogels in aqueous solution exhibited sustained release of VCM up to 72 h, while the in vitro antibacterial test based on the VCM-loaded hydrogel showed an efficient Methicillin-Resistant S. aureus （MRSA） inhibition extending out to 7 days. These results demonstrated that the biodegradable hydrogels which formed by in situ photo-cross linking would be promising as scaffolds or coatings for local antibacterial drug release in tissue engineering.     

聚L-谷氨酸乙酯手性固定相的制备及色谱评价

合成了聚L-谷氨酸乙酯,并将其三氯甲烷溶液涂敷在3-氨丙基三乙氧基硅胶上,合成和表征了聚L-谷氨酸乙酯涂敷手性固定相,以不同比例的正己烷-异丙醇、正己烷-无水乙醇为流动相,探究了在正相液相色谱条件下聚L-谷氨酸乙酯涂敷手性固定相对部分手性化合物和位置异构体的拆分能力。实验结果表明:有4种手性化合物对映体(联糠醛、奥美拉唑、萘普生、四咪唑)和9种位置异构体(o,m,p-碘苯胺、o,m,p-氯苯胺、o,m,p-溴苯胺、o,m,p-硝基苯胺、o,m,p-甲苯胺、o,m,p-氯酚、o,m,p-二硝基苯、o,m,p-苯二酚、o,m,p-氨基苯酚)得到不同程度的拆分,表明聚L-谷氨酸乙酯涂敷手性固定相能对手性药品进行一定的拆分,对位置异构体有较好的分离能力。     

The dynamic changes of glutamate immunoreactivity in cochleae inner hair cells of guinea pigs after noise exposure

To investigate the glutamate-like immunoreactivity (Glu-IR) changes in inner hair cells (IHCs) of guinea pigs cochlear after noise exposure. Guinea pigs were distributed into 6 groups including control group (g1), and groups of immediately (g2), 8 hours (g3), 1 day (g4), 3 days (g5) and 7days (g6) after noise exposure. The experimental groups were exposed to 120 dBLp 1/3 octave 4 kHz narrow band noise for 4 hours to ruin the organ of Corti. The first turn of the organ of Corti was dissected to make ultrathin sections and under went immunoelectron study. The density of gold particles of Glu-IR in IHCs was measured. Results showed that Glu-IR in IHCs after noise exposure changed dynamically. The density of gold particle in IHCs of g2 significantly increased (p < 0.001) compared with gl and decreased in g3 (p < 0.001), whereas there were no significant difference in the groups of g4, g5 and g6 (p > 0.05). The results suggest that there may be glutamate autoreceptors in the membrane of IHCs and the glutamat     

高效液相色谱法测定羊水中兴奋性氨基酸、抑制性氨基酸的含量

建立了反相高效液相色谱法测定羊水中兴奋性氨基酸天门冬氨酸、谷氨酸,抑制性氨基酸甘氨酸含量的方法,色谱柱为LUNAC18柱(4.6mm×250mm,5μm),流动相为乙腈水(V/V),按低压梯度洗脱,梯度系统0～4min,乙腈40%;4～20min,乙腈40%～52%;20～30min,乙腈52%～60%;30～40min,乙腈60%～40%。流速0.8mL/min,柱温40℃,紫外检测波长260nm;进样量10μL。结果显示,天门冬氨酸、谷氨酸和甘氨酸三者的线性范围均为2.5～85mg/L;标准加入的回收率为99.6%～102.6%。本方法灵敏度高、测定结果可靠。用本方法对201例不同孕期的羊水作兴奋性和抑制性氨基酸检测,发现羊水中3种氨基酸随妊娠进展而增加的趋势,胎儿畸形或宫内缺氧时羊水中这3种氨基酸水平明显升高。     

含有不同添加剂的明胶膜对Am（Ⅲ）／Eu（Ⅲ）的吸附研究

研究了分别添加γ-聚谷氨酸(γ-PGA)及1,4,7,10-四杂环十二烷基四乙酸(DOTA)的两种明胶膜对Am(Ⅲ)/Eu(Ⅲ)的吸附行为。结果表明,添加γ-PGA的明胶膜,在2.0 mol/L硝酸介质中,γ-PGA∶明胶的质量比为1∶5、吸附时间在15h以上时,对Eu3 的吸附率达38.6%,而对Am3 基本不吸附;添加DOTA的明胶膜,在2.0 mol/L硝酸介质中,DOTA∶明胶的质量比为1∶5、吸附时间在15h以上时,对Am3 的吸附率达41.3%,而对Eu3 的吸附率为5.1%。     

聚谷氨酸苄酯掺杂硅胶用于拆分氧氟沙星对映体

通过将聚谷氨酸苄酯（PBLG）掺杂在硅胶中,建立了一种分离手性物质氧氟沙星对映体的方法。以壳聚糖为引发剂,利用开环聚合方法合成了PBLG。将PBLG掺杂在硅胶G中制备薄层色谱板,实现了对氧氟沙星外消旋体的拆分。考察了展开溶剂体系、不同比例溶剂、展开温度和展开时间对手性拆分氧氟沙星对映异构体的影响。结果表明,该薄层色谱板拆分氧氟沙星对映异构体的最佳条件为：0.5 g PBLG掺杂在2 g硅胶G中,以乙腈-甲醇（V/V=2∶1）混合溶剂为展开体系,35℃下展开30 min。氧氟沙星对映体单体在薄层色谱板上的手性分离因子（α）范围为2.62～6.12,实现了基线分离。