A Bioanalytical Chemistry Experiment for Undergraduate Students: Biosensors Based on Metal Nanoparticles

We describe an undergraduate laboratory experiment designed as an introduction to modern concepts of a biosensor based on gold nanoparticles. The objectives are to (i) expose students to the development stages of a modern biosensor, (ii) apply electrochemical methods to deposit gold nanoparticles onto electrode surfaces, (iii) immobilize an enzyme (tyrosinase) using glutaraldehyde chemistry, and (iv) perform quantitative analysis of phenol using a biosensor with amperometric detection. The biosensor was characterized in terms of analytical performance (detection limit, linear range, response time, and sensitivity). The Michaelis–Menten kinetic constants of the immobilized enzyme were evaluated by the ability of the enzyme to catalyze the transformation of phenol to quinone, which can be detected electrochemically upon application of an electrical potential. The experiment reinforces the electrochemical and biochemical principles learned in a typical lecture format and can be realized in two sessions of a three-hour laboratory. The procedure is simple and could be adapted for students majoring in chemistry, biochemistry, and biomolecular science.