Bioanalytical experiments for the undergraduate laboratory : monitoring glucose in sports drinks

This paper describes two complementary bioanalytical experiments for analyzing the concentration of glucose in sports drinks. The first experiment is a spectrophotometric enzyme assay employing the enzymes glucose oxidase (GOx) and horseradish peroxidase (HRP). The glucose is oxidized by the GOx, producing hydrogen peroxide, which is the substrate for HRP. In the reduction of the H2O2 a chromogen is oxidized, causing a color change. In the partner experiment, the GOx is immobilized on a platinum electrode using a dialysis membrane. The hydrogen peroxide produced in the enzyme reaction is monitored amperometrically by oxidizing the hydrogen peroxide produced. The simple method of preparing the enzyme electrode is useful in demonstrating the important parameters in defining the response of enzyme electrodes. The same sports drinks are analyzed in both experiments. The two experiments together illustrate the advantage of bioanalysis in analyzing complex samples with minimal sample preparation.

The self-assembled monolayer modification of electrodes - some recent advances in biological application

The modification of an electrode surface at the molecular level using the technique of depositing self-assembled monolayers (SAM) is a typical example of the techniques used in nanotechnology, from the process "bottom up", which is to create a nanostructure by successive additions of molecular or atomic entities on a surface. This article presents some recent advances in the field, with examples: the development of systems Sat hybridized with biomolecules, nanoparticles or nanotubes in bioelectronics, the use of switchable electrodes to study the adhesion and migration of biological cells , and the integration of molecular son in the SAM to recognize and allow the transduction of a biological response allowing the practice of electrochemistry in a complex biological environment.

Protein electrochemistry using aligned carbon nanotube arrays

The remarkable electrocatalytic properties and small size of carbon nanotubes make them ideal for achieving direct electron transfer to proteins, important in understanding their redox properties and in the development of biosensors. Here, we report shortened SWNTs can be aligned normal to an electrode by self-assembly and act as molecular wires to allow electrical communication between the underlying electrode and redox proteins covalently attached to the ends of the SWNTs, in this case, microperoxidase MP-11. The efficiency of the electron transfer through the SWNTs is demonstrated by electrodes modified with tubes cut to different lengths having the same electron-transfer rate constant.