Controlled chemical modification of the internal surface of photonic crystal fibers for application as biosensitive elements

Photonic crystal fibers (PCF) are one of the most promising materials for creation of constructive elements for bio-, drug and contaminant sensing based on unique optical properties of the PCF as effective nanosized optical signal collectors. In order to provide efficient and controllable binding of biomolecules, the internal surface of glass hollow core photonic crystal fibers (HC-PCF) has been chemically modified with silanol groups and functionalized with (3-aminopropyl) triethoxysilane (APTES). The shift of local maxima in the HC-PCF transmission spectrum has been selected as a signal for estimating the amount of silanol groups on the HC-PCF inner surface. The relationship between amount of silanol groups on the HC-PCF inner surface and efficiency of following APTES functionalization has been evaluated. Covalent binding of horseradish peroxidase (chosen as a model protein) on functionalized PCF inner surface has been performed successively, thus verifying the possibility of creating a biosensitive element.     

Poly(brilliant cresyl blue) electrogenerated on single-walled carbon nanotubes modified electrode and its application in mediated biosensing system

Single-walled carbon nanotubes (SWCNTs) functionalized with carboxylic acid groups were cast to glassy carbon electrode (GCE) to construct a three-dimensional nano-micro structured scaffold. Brilliant cresyl blue (BCB) was electropolymerized on the above-mentioned SWCNTs/GCE using continuous cycling between −0.7 and 0.9 V vs. SCE. PolyBCB yielded on SWCNTs/GCE exhibited the enhanced electrochemical redox behavior compared with that electrogenerated on bare GCE. The apparent surface coverage of PolyBCB obtained by SWCNTs/GCE was at least 10 times higher than that obtained by bare GCE, namely 4.8 × 10⁻⁹ and 3.6 × 10⁻¹⁰ mol cm⁻². The cyclic voltammograms recorded by PolyBCB/SWCNTs/GCE exhibited well-defined two peaks located at −0.25 V and −0.06 V, respectively, with a surface-controlled mechanism. In addition, morphologies of PolyBCB electrogenerated on GCE and SWCNTS/GCE were characterized by atomic force microscopy. Finally, this proposed PolyBCB/SWCNTs/GCE was used in the construction of the second-generation biosensors to hydrogen peroxide and glucose, with the enhanced analytical performance.     

Carbon felt-based bioelectrocatalytic flow-through detectors: Highly sensitive amperometric determination of H2O2 based on a direct electrochemistry of covalently modified horseradish peroxidase using cyanuric chloride as a linking agent

Horseradish peroxidase (HRP) was chemically modified using cyanuric chloride (CC) as a linking agent onto a carbon felt (CF), which is a microelectrode ensemble of micro carbon fiber (>7 μm, diameter) with a random three-dimensional structure. The resulting HRP-modified CF (HRP-ccCF) exhibited well-defined redox waves based on the HRP heme Fe^III/Fe^II redox couple at −0.23 V vs. Ag/AgCl (at pH 7.0), while the HRP-adsorbed CF (HRP-CF) showed no apparent redox couple in the same potential range, indicating that the chemical modification of HRP via CC facilitated the direct electron transfer (DET) between HRP and CF. The apparent heterogeneous electron transfer rate constant k_s was estimated to be 35 s⁻¹. Cyclic voltammetry and electrochemical impedance spectroscopy revealed that the interfacial properties (i.e., structure, morphology of enzyme-layer) of covalently modified HRP (HRP-ccCF) and physically adsorbed HRP (HRP-CF) are different, resulting in the difference in the electron transfer properties. The HRP-ccCF was successfully used as a working electrode unit in bioelectrocatalytic flow-through detector for highly sensitive amperometric determination of H₂O₂. Under the optimized conditions (i.e., applied potential, 0 V vs. Ag/AgCl; carrier flow rate, 3.25 ml/min; and carrier pH 7.0), the cathodic peak current of H₂O₂ linearly increased up to 3 μM (sensitivity, 1.94 μA/μM; the detection limit, 0.08 μM [S/N = 3]) with sample through-put of ca. 90 samples/h.     

A label-free amperometric immunosensor based on horseradish peroxidase functionalized carbon nanotubes and bilayer gold nanoparticles

In this work, a novel label-free amperometric immunosensor has been constructed for detecting α-1-fetoprotein (AFP) based on nanocomposite of horseradish peroxidase (HRP) labeled carbon nanotubes (CNTs). First, the gold nanoparticles (AuNPs) were electrodeposited on the surface of the glass carbon electrode by electrochemical reduction of gold chloride tetrahydrate (HAuCl₄) to immobilize horseradish peroxidase labeled carbon nanotubes (HRP-CNTs). Then HRP-CNTs bioconjugate was immobilized on the surface of the electrodeposited AuNPs layer by the combination of forces (coordination and electrostatic force). Subsequently, it was immersed into gold colloidal nanoparticles (GNPs) solution, which was used to immobilize antibody biomolecules (anti-AFP). Enhanced sensitivity was obtained by using bioconjugates featuring HRP labeled (HRP-CNTs), which had lager specific surface area and good electronic catalysis (current response signal) compared to carbon nanotubes. Under optimized conditions, the linear ranges were from 0.2 to 200 ng mL⁻¹ with a detection limit of 0.067 ng mL⁻¹ (at an S/N of 3). The proposed immunosenor showed good precision, acceptable stability and reproducibility and could be used for the detection AFP in normal human serum, which provided a potential alternative tool for the detection of protein in clinical diagnosis.     

日本血吸虫抗体电化学免疫传感器研究

该文研制了一种高灵敏的基于辣根过氧化物酶(HRP)放大的电化学免疫传感器用于日本血吸虫抗体的检测.实验采用夹心法的模式,在电极表面固定了日本血吸虫抗原(SjAg),用以捕获血清中的日本血吸虫抗体(SjAb),然后再与辣根过氧化物酶(HRP)标记的羊抗兔IgG二抗形成免疫复合物.用计时安培法检测HRP酶催化H2O2还原对苯二酚底物产牛的电流,其大小与日本血吸虫抗体(SjAb)浓度在一定范围内成正比.对免疫反应的实验条件如电极表面固定抗原的浓度,HRP酶标二抗的浓度进行了优化.此外,还考察了其它蛋白质对测定结果的影响.结果表明,该方法操作简单,灵敏度高,线性范围宽,检测下限低.     

过氧化物酶活性检测方法的研究

研究了一种新的过氧化酶的活性检测方法，以苯胺为底物进行测定。通过试验确定了该方法适宜的工作条件，包括酶浓度、底物浓度、H2O2浓度、温度、pH值等。同时确定了酶活力检测的一些相关条件(如温度、pH值等)。实验表明，该方法有较高的精密度，且简便易行。     

糙米被玉米象感染后其储藏品质变化研究

以粳糙米为材料,设定不同的虫口密度,检测不同感染时间糙米的降落数值、脂肪酸值、POD等储藏品质指标,采用SPSS等方法分析虫口密度和感染时间对糙米储藏品质的影响.结果表明:随着虫口密度的增加和侵染时间的延长,脂肪酸值上升,降落数值下降;POD活性在前50 d无明显规律,50 d后迅速下降;虫口密度超过100头/300 g时,30 d后脂肪酸、降落数值就发生剧烈变化;不同虫口密度感染的糙米样品,其降落数值、脂肪酸值在不同感染时间呈现显著差异性;降落数值与虫口密度和感染时间呈显著负相关,脂肪酸值与虫口密度和感染时间呈显著正相关,POD与感染时间负相关.     

微生物对煤的溶解研究进展

煤的微生物溶化是煤炭综合利用研究中的新领域。从溶煤微生物，微生物溶酶活性物及溶煤机理，溶解煤的酶木素过氧化物酶和锰过氧化物酶，微生物溶煤产物分析及微生物溶煤产物的应用等方面详细地探讨了煤的微生物液化研究的现状，指出了寻求高效菌种，开发溶煤新产品及探索溶煤产物的新用途将是今后微生物转化的主要研究方向。     

氯霉素酶联免疫分析方法的建立

以兔抗氯霉素多抗为包被抗体,氯霉素（CAP）辣根过氧化物酶连接物为标记物,四甲基联苯胺（TMB）为显色底物,建立了氯霉素直接竞争酶联免疫分析（CAP-EIA）方法.本方法灵敏度为0.046 μg /L,批内变异系数＜10%,批间变异系数＜24%,回收率62%～145%.用牛奶样品预处理所得上清液为稀释液做得稀释实验,相关方程为y=3.988x-0.234, 相关系数为0.999.标准曲线范围为0.1～10 μg /L.