On-line microdialysis system with poly(amidoamine)-encapsulated Pt nanoparticles biosensor for glutamate sensing in vivo

In this work, an amine-terminated poly (amidoamine) dendrimer containing Pt nanoparticles (PAMAM/Pt) nanocomposite was synthesized and a novel amperometric H₂O₂ biosensor based on PAMAM/Pt and MWCNTs was developed. The resulting film of MWCNTs/PAMAM/Pt was characterized by transmission electron microscopy (TEM), linear sweep voltammetry (LSV) and amperometric i-t curve. It demonstrates excellent electrocatalytic responses toward the reduction of H₂O₂ at -200mV (vs.SCE) without HRP participation. Immobilized with glutamate oxidase (GlutaOx), an effective glutamate biosensor, was fabricated, and the in vivo detection for glutamate was realized combining with the on-line microdialysis system. The glutamate biosensor showed good linear range from 1.0μM to 50.0μM with the detection limit of 0.5μM (S/N=3). The basal level of glutamate in the striatum of rat was detected continuously with this on-line system and was calculated to be 5.80±0.12μM (n=3). This method was proved to be sensitive and selective and may be feasible in the further application of physiology and pathology.