Monitoring RAYT activity by surface plasmon resonance biosensor

Development of an aptamer-based SPR-biosensor for the determination of kanamycin residues in foods

A biosensor in which an affinity reaction occurs in the sensitive microzone through the use of specific aptamers to determine kanamycin residues in agri-food samples has been developed. It is an irreversible and continuous flow aptameric biosensor (aptasensor) in which the signal variations are monitored by surface plasmon resonance (SPR) measurements based on the specific interaction of the aptamer with the antibiotic. The signal variation is proportional to the analyte concentration. Graphene is known for efficient binding of molecules with its π-electron system, so a monolayer of graphene prepared from chemical vapor deposition (CVD) has been compared to a multilayer of graphene made from reduced graphene oxide (rGO) for immobilization of the aptamer on the gold surface of the physicochemical transducer. The best results have been obtained with CVD graphene. The dynamic range was between 1 and 100 μmol L^-1 of kanamycin concentration (r² = 0.9981, n = 7, r = 4), with a limit of detection of 285 nmol L^-1 and a sampling frequency of 6 h^-1. The precision, expressed as relative standard deviation (RSD%), was established in the range of 1.49 and 3.89%, calculated for 1, 10, and 50 μmol L^-1. The selectivity was studied applying the described method to determine other antibiotics, obtaining no significant difference in the analytical signal. The method was applied to determine kanamycin residues in milk samples with recovery values ranging between 90 and 96%.

Synthetic biology and biomimetic chemistry as converging technologies fostering a new generation of smart biosensors

Biosensors are powerful tunable systems able to switch between an ON/OFF status in response to an external stimulus. This extraordinary property could be engineered by adopting synthetic biology or biomimetic chemistry to obtain tailor-made biosensors having the desired requirements of robustness, sensitivity and detection range. Recent advances in both disciplines, in fact, allow to re-design the configuration of the sensing elements - either by modifying toggle switches and gene networks, or by producing synthetic entities mimicking key properties of natural molecules. The present review considered the role of synthetic biology in sustaining biosensor technology, reporting examples from the literature and reflecting on the features that make it a useful tool for designing and constructing engineered biological systems for sensing application. Besides, a section dedicated to bioinspired synthetic molecules as powerful tools to enhance biosensor potential is reported, and treated as an extension of the concept of biomimetic chemistry, where organic synthesis is used to generate artificial molecules that mimic natural molecules. Thus, the design of synthetic molecules, such as aptamers, biomimetics, molecular imprinting polymers, peptide nucleic acids, and ribozymes were encompassed as "products" of biomimetic chemistry.