Amperometric glutamate biosensor based on self-assembling glutamate dehydrogenase and dendrimer-encapsulated platinum nanoparticles onto carbon nanotubes

A novel amperometric biosensor based on self-assembling glutamate dehydrogenase (GLDH) and poly(amidoamine) dendrimer-encapsulated platinum nanoparticles (Pt-PAMAM) onto multiwall carbon nanotubes (CNTs) has been developed for the determination of glutamate. The formation of the self-assembled (GLDH/Pt-PAMAM)n/CNTs construction was investigated by ζ-potential and high resolution transmission electron microscopy (HRTEM). The results indicated the uniform growth of the layer-by-layer nanostructures onto carboxyl-functionalized CNTs. The electrocatalytic property of the (GLDH/Pt-PAMAM)n/CNTs modified electrode to glutamate in presence of NAD+ (β-nicotinamide adenine dinucleotide, 0.1 mM) was investigated at a low overpotential 0.2 V by electrochemical measurements. The results showed it had series of attractive characteristics, such as a large determination range (0.2–250 μM), a short response time (within 3 s), a high sensitivity (433 μA/mM−1 cm2) and good stability (85% remains after 4 weeks).