Development of a Cholesterol Biosensor by Chronoamperometric Deposition of Polyaniline-Ag Nanocomposites

Chronoamperometry was employed to prepare polyaniline-p-toluene sulphonic acid-silver (PANI-pTSA-Ag) nanocomposite film on indium tin oxide–coated glass plate to fabricate a cholesterol bioelectrode. The authors observed the high sensitivity of 36.3 µA/mg/dL with a fast response time of 10 s in the range of 20–400 mg/dL for the bioelectrode. The bioelectrode exhibits uniform activity for 50 days under refrigerated conditions. Attempts have been made to utilize this bioelectrode for estimation of total cholesterol in blood serum samples.     

LBL技术制备有机/无机纳米复合薄膜研究进展

将高分子和各种功能的无机纳米粒子通过层层吸附自组装技术进行组装,制备厚度可控和稳定性好的有机/无机纳米复合薄膜。综述了该领域研究的最新进展,介绍了利用LBL技术制备有机/无机纳米复合薄膜的方法,并对利用LBL技术制备有机/无机纳米复合薄膜的发展趋势作了展望。     

Cholesterol biosensor based on electrochemically prepared polyaniline conducting polymer film in presence of a nonionic surfactant

Cholesterol biosensor has been fabricated by covalently coupling cholesterol oxidase (ChOx) via glutaraldehyde onto electrochemically prepared polyaniline film in presence of TritonX-100 [4-(1,1,3,3-tetramethylbutyl) phenyl polyethylene glycol], a non-ionic surfactant onto indium-tin-oxide (ITO) glass substrate. These ChOx/PANI-TX-100/ITO bioelectrodes have been characterized using Fourier transform infrared (FTIR) spectroscopy, cyclic voltammetry (CV) and scanning electron microscopy (SEM) techniques. The results of response measurements carried out on ChOx/PANI-TX-100/ITO bioelectrodes using amperometric and photometric techniques, reveal detection limit as 5 mg/dl, linearity from 5 to 400 mg/dl of cholesterol and sensitivity as 131 μA/(mg/dl cm⁻²). These biosensing electrodes are thermally stable up to 65 °C, can be used about 20 times and have a shelf-life of about 10 weeks when stored at 4 °C. Attempts have also been made to utilize the ChOx/PANI-TX-100/ITO bioelectrodes for estimation of free cholesterol concentration in serum samples.     

Adsorption of Methane,Ethane, Ethylene,and Carbon Dioxide on X,Y, L,and M Zeolites Using a Gas Chromatography Pulse Technique

Abstract

Sorption of methane, ethane, ethylene and carbon dioxide in NaX, NaY, HY, CeNaY, KL, HKL, NaM, and HM zeolites at 303–473 K has been investigated using a gas chromatography pulse technique. The zeolites have been compared for the heat of sorption of the sorbates at near-zero sorbate loading and also for the specific retention volume (or thermodynamic sorption equilibrium constant) of ethane, ethylene, and carbon dioxide relative to that of methane.