琼脂糖固载辣根过氧化物酶的直接电化学行为研究

用琼脂糖将辣根过氧化物酶(HRP)固定到玻碳电极(GCE)表面,制备了HRP-琼脂糖膜修饰电极。研究发现包埋在琼脂糖膜中的辣根过氧化物酶可与电极直接传递电子,在磷酸盐缓冲溶液和磷酸盐缓冲溶液/乙醇混合液中均可得到一对辣根过氧化物酶辅基血红素Fe(Ⅲ)/Fe(Ⅱ)电对的可逆氧化还原峰,式电势分别为-0.392V(vs SCE)和-0.412V(vs SCE)。式电势随缓冲溶液pH值增加而负移,且呈线性关系,直线斜率为-56.0mV/pH。这说明辣根过氧化物酶的电子传递过程伴随有质子的转移。     

石墨电极上甲基纤维素膜固载辣根过氧化物酶的直接电化学

用甲基纤维素（MC）将辣根过氧化物酶（HRP）固定在热裂解石墨电极表面,制备了HRP-MC膜修饰电极.包埋在甲基纤维素膜中的辣根过氧化物酶可以与电极直接传递电子.在pH 7.0的磷酸盐缓冲溶液中可得到一对可逆的辣根过氧化物酶辅基血红素Fe（Ⅲ）/Fe（Ⅱ）电对氧化还原峰,式电势为-0.349 V（vs SCE）.其式电势随溶液pH值增加而负移且成线性关系,直线斜率为-40.0 mV/pH,说明辣根过氧化物酶的电子传递过程伴随有质子的转移.并研究了HRP-MC膜修饰电极对H2O2、NO的电催化性质.     

琼脂糖膜固载辣根过氧化物酶催化还原过氧化物的研究

用琼脂糖(agarose)水凝胶将辣根过氧化物酶(HRP)固定在玻碳电极(GCE)表面,制备了HRP-Agarose膜修饰电极。在水-乙醇混合溶液中,包埋在琼脂糖水凝胶中的HRP可以与电极直接传递电子,并且能催化还原H2O2、过氧化丁酮、氢过氧化叔丁基、氢过氧化异丙基苯等过氧化物和NO。HRP-Agarose膜修饰电极具有较好的稳定性和重现性,可用于上述过氧化物和亚硝酸盐的定量检测。     

固定化肌红蛋白的电化学和电催化性能研究

用海藻酸钠(Sodium Alginate,SA)将肌红蛋白(Mb)固定在热裂解石墨电极表面,制备了Mb-SA膜修饰电极。包埋在SA膜中的Mb在磷酸盐缓冲溶液(PBS)和乙醇混合溶液中与电极直接传递电子,得到一对对称的Mb辅基血红素Fe(III)/Fe(II)电对的氧化还原峰,式电势为-0.339V(vs SCE)。式电势随缓冲溶液pH增加而负移且成线性关系,直线斜率为-47.0mV/pH,说明肌红蛋白的电子传递过程伴随有质子的转移。并研究了Mb-SA膜修饰电极在水-乙醇混合溶液中催化还原H2O2和NO,该修饰电极可用于H2O2和NO2-的定量检测。     

血红蛋白在海藻酸钠膜中的电化学和类酶活性研究

用海藻酸钠(SA)将血红蛋白(Hb)固定到热裂解石墨电极表面,制备了Hb-SA膜修饰电极。包埋在SA膜中的Hb在磷酸盐缓冲溶液和乙醇混合溶液中与电极直接传递电子,得到一对对称的血红蛋白辅基血红素Fe(Ⅲ)/Fe(Ⅱ)电对的可逆氧化还原峰。其式电势随缓冲溶液pH值增加而负移,且呈线性关系,这说明血红蛋白的电子传递过程伴随有质子的转移。并考察了Hb-SA膜修饰电极在缓冲溶液和乙醇混合溶液中对氧气、双氧水、一氧化氮和六氯乙烷的电催化性质。     

硬脂酸二茂铁酯L—B膜修饰SnO2电极的阻抗研究

测定了二茂铁衍生物——硬脂酸二茂铁酯L-B膜修饰SnO_2电极在Fe(CN)_6~(3-/4-)溶液中的阻抗性能,用单纯形法求出了等效电路中的元件参数值,计算了电极反应速度常数K_s。从分析SnO_2电极修饰不同层的硬脂酸二茂铁酯L-B膜的界面阻抗和电极反应的动力学性能,表明与在固相中研究的硬脂酸二茂铁酯L-B膜的阻抗性能明显不同,在Fe(CN)_6~(3-/4-)溶液中表现了电活性分子修饰电极的界面阻抗行为,进一步证实了修饰在SnO_2电极上的硬脂酸二茂铁酯L-B膜在Fe(CN)_6~(3-/4-)的氧化还原电极反应过程中,起电荷传递的中介作用。     

酶功能化Co_3O_4-Pt纳米复合材料修饰电极的制备及电化学性能

基于水热法合成了形貌均一的纳米Co_3O_4,利用其强催化性能将其连同纳米Pt和辣根过氧化物酶(HRP)层层修饰于金电极表面,最终构建出对H_2O_2具有三重催化作用的新型纳米复合材料Co_3O_4-Pt-HRP修饰电极,并将其应用于对H_2O_2的浓度检测。实验结果发现,纳米Co_3O_4与纳米Pt的催化作用相互协同,并且纳米Pt较大的比表面积和优良的生物相容性增加了后续辣根过氧化物酶的负载量与生物催化活性,从而提高了传感器的灵敏度。在优化条件下,对H_2O_2浓度的检测范围为2.0μmol/L~7.1 mmol/L,检出限为0.9μmol/L。此外,该传感器还表现出较高的选择性、稳定性和灵敏度。     

电活性分子L-B膜修饰CdSe薄膜电极的光电化学研究

用电活性分子——硬脂酸二茂铁酯L-B膜修饰了薄膜CdSe电极,在单色光650nm光照下用循环伏安法研究修饰的薄膜电极的光电化学性能。研究结果指出经多层L-B膜修饰后,薄膜CdSe电极的,I-V性能和光稳定性都有明显改善。用界面能级关系讨论了硬脂酸二茂铁酯L-B膜在光照的CdSe薄膜/Fe(CN)_6~(4-)溶液界面起传递电荷的中介作用,加速了界面的电荷转移。     

溶剂挥发诱导苯丙氨酸二肽自组装结构的电化学生物传感研究

将乙腈诱导苯丙氨酸二肽自组装生成的蒲公英状微晶聚集体修饰于玻碳电极上作为酶载体,采用戊二醛交联固定辣根过氧化物酶(HRP),Nafion溶液包埋保护HRP,制备过氧化氢生物传感器。该传感器对H2O2表现出良好的催化还原特性,其响应线性范围为5.0×10-7～6.0×10-4mol/L,检出限为2.5×10-7mol/L(S/N=3)。米氏常数为0.83 mmol/L,表明所固定的酶具有较高的生物活性,且与过氧化氢有较强的亲和能力。这种采用寡肽自组装产物修饰电极的方法也可为制备其他酶传感器提供借鉴。     

基于花状ZnO-CHIT复合材料的安培型过氧化氢生物传感器

将水热法制备的纳米花状结构ZaO分散在壳聚糖中构成ZnO-壳聚糖复合膜来固定辣根过氧化物酶(HRP)构建安培型过氧化氢生物传感器.结果表明,在相同过氧化氢浓度下,加入纳米颗粒的电极的电流响应值比未加颗粒的高约40倍.ZnO-壳聚糖修饰电极对过氧化氢具有明显的增敏效应,线性范围为1.0×10～5.0×10-3mol/L,关系数为0.9977;检测下限为1.0×10-7mg/L(信噪比S/N=3).     

Entrapment of porous and stable concanavalin A–peroxidase complex into hybrid calcium alginate–pectin gel

Ammonium sulfate‐fractionated proteins of turnip (Brassica rapa) were used for the simultaneous purification and immobilization of peroxidase by using crude jack bean extract. The concanavalin A–turnip peroxidase complex retained nearly 70% of the original activity. Calcium alginate–pectin‐entrapped soluble turnip peroxidase and the concanavalin A complex of peroxidase retained 63% and 52% of the original activity, respectively. The concanavalin A–peroxidase complex, the alginate–pectin‐entrapped soluble peroxidase and the alginate–pectin‐entrapped concanavalin A–peroxidase complex showed very high stability against denaturation mediated by heat, pH, urea, organic solvents and detergents. The exposure of soluble and immobilized turnip peroxidase to trypsin resulted in an enhancement of the peroxidase activity. The concanavalin A–peroxidase complex entrapped preparation was markedly more stable as compared with the directly entrapped soluble enzyme preparation. The results suggested that such preparations have great potential in the construction of bioreactors to be used for the remediation of aromatic compounds present in polluted wastewater/industrial effluents. Copyright © 2006 Society of Chemical Industry     

Preparation and in vitro evaluation of new pH‐sensitive hydrogel beads for oral delivery of protein drugs

New biodegradable pH‐responsive hydrogel beads based on chemically modified chitosan and sodium alginate were prepared and characterized for the controlled release study of protein drugs in the small intestine. The ionotropic gelation reaction was carried out under mild aqueous conditions, which should be appropriate for the retention of the biological activity of an uploaded protein drug. The equilibrium swelling studies were carried out for the hydrogel beads at 37°C in simulated gastric (SGF) and simulated intestinal (SIF) fluids. Bovine serum albumin (BSA), a model for protein drugs was entrapped in the hydrogels and the in vitro drug release profiles were established at 37°C in SGF and SIF. The preliminary investigation of the hydrogel beads prepared in this study showed high entrapment efficiency (up to 97%) and promising release profiles of BSA. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Preparation and electroresponsive property of poly(vinyl alcohol)/sodium alginate composite hydrogel

Poly(vinyl alcohol) (PVA)/sodium alginate composite hydrogel was prepared by solidifing the blending solution of PVA and sodium alginate, then freezing and thawing repeatedly. In the direct current electric field, the composite hydrogel in aqueous NaCl solution swelled, contracted, and bent. The gel's bending speed and maximum bending degree increased with increase in the electric field intensity and the concentration of NaCl solution. The maximum bending degree increased with increase in the sodium alginate content in the composition hydrogel. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 3493–3496, 2006     

包埋嵌段共聚物的水凝胶萃取低浓度有机物

包埋聚氧乙烯－聚氧丙烯－聚氧乙烯嵌段共聚物的海藻酸钠水凝胶具有萃取水中低浓度有机物的能力,疏水性强的嵌段共聚物具有较强的萃取能力。水凝胶经过干燥脱水、有机溶剂浸泡和吸水再生,可以循环再利用。     

单宁酸对海藻酸钠/壳聚糖微球性能的影响

研究了单宁酸的引入对海藻酸钠/壳聚糖水凝胶在微球化和微胶囊化应用性能方面的影响.首先制备了单宁酸交联改性的海藻酸钠/壳聚糖水凝胶微球.利用傅里叶变换红外光谱分析了共混物分子结构间的相互作用,采用热重分析仪考察了微球热稳定性,并研究了单宁酸的加入对微球粒径、含水量和溶胀性的影响.结果表明由于单宁酸与海藻酸钠/壳聚糖之间的...     

Controlled release of berberine hydrochloride from alginate microspheres embedded within carboxymethyl chitosan hydrogels

Berberine hydrochloride is a natural medicine with wide clinical application. In this article, berberine hydrochloride was entrapped into alginate microspheres via an emulsification/gelation method. The size distribution of the microspheres was determined by a laser particle sizer. Drug distribution within the microspheres was determined by confocal laser scanning microscopy. Those drug‐loaded microspheres were further entrapped into carboxymethyl chitosan (CMC) hydrogel to form a new drug‐delivery system (DDS). The surface morphology of the DDS was observed using metallographic microscopy and scanning electron microscopy (SEM). The compression strength of the DDSs with alginate microspheres was found significantly higher than that of the pure hydrogel. The drug‐release performances of the DDS in phosphate buffer solution (PBS, pH 7.4), saline solution (pH 6.3), and hydrochloric acid solution (HAS, pH 1.2) were also studied. Decay of the DDS in PBS within 72–80 h results in a faster release; however, the steady release in saline solution could last for all the testing period without cleavage of the DDS. In HAS, because of the shrinkage of the DDS, release is fast in the first period and remains steady later. The DDS exhibits prospective in controlled steady release of drugs. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

A self-healing and conductive ionic hydrogel based on polysaccharides for flexible sensors

In this study, we proposed a self-healing conductive hydrogel based on polysaccharides and Li⁺ to serve as flexible sensors. At first, the oxidized sodium alginate(OSA) was obtained through the oxidation reaction of sodium alginate(SA). Then OSA, carboxymethyl chitosan(CMC), and agarose(AGO) were dissolved in Li Cl solution, respectively. Finally, the hydrogel was obtained through heating, mixing, and cooling processes. Because of the Schiff base structure and hydrogen bonding, the hy...     

Construction and evaluation of the hydroxypropyl methyl cellulose-sodium alginate composite hydrogel system for sustained drug release

We prepared a hydroxypropyl methyl cellulose-sodium alginate (HPMC-SA) composite hydrogel with a membrane covering the semi-interpenetrating network based on a semi-synthetic polymer hydroxypropyl methyl cellulose (HPMC) and a natural polymer sodium alginate (SA) by Ca²⁺ crosslinking and polyelectrolyte complexation with chitosan (CS) covering the hydrogel surface. The physiochemical properties of HPMC-SA hydrogels were evaluated by scanning electron microscopy, infrared spectrum, X-ray diffraction, and thermogravimetric analysis. The swelling ratio of the HPMC-SA composite hydrogel in simulated gastrointestinal fluid was measured. The drug release behavior of the HPMC-SA composite hydrogel for macro-molecular and small-molecule drugs was evaluated by using bovine serum albumin, metformin hydrochloride, and indomethacin as model drugs. The results showed that the HPMC-SA hydrogel had good water absorption and degradability, an increased swelling ratio of 55, and a prolonged time for maximum swelling degree of 50 h. Moreover, the hydrogel exhibited higher drug-loading capacity and improvements in the sustained release of bio-macromolecules, demonstrating its potential as a drug carrier for biomedical applications.