Luciferin incorporation in the structure of acrylic microspheres with subsequent confinement in a polymeric film: A...

The controlled release of coreactants at the sensing tip of a biosensor is a possible approach to develop self-contained devices. For luciferin which is a firefly luciferase cosubstrate, a new method of retention is evaluated. The two-step procedure consists of incorporating the substrate in acrylic microspheres during their formation, these last being then confined in a PVA SbQ film. When associated with a compartmentalised trienzymatic sequence (adenylate kinase, creatine kinase and luciferase), such a complex matrix ensures the internal delivery of the cosubstrate in the enzymatic microenvironment at a controlled rate. For the three adenylic nucleotides (ATP, ADP and AMP), the self-containment working time is 3 h of continuous and reproducible assays. The sensitivity of the fibre optic biosensor represents, for ATP, 30% of that obtained when luciferin is supplied in solution whereas for ADP and AMP, the values are about 80% of the reference ones.