Plasma surface modification of polymers for sensor applications.

Polymeric sensors play an increasingly important role in monitoring the environment we live in, providing relevant information for a host of applications. Among them, significant efforts have been made to fabricate polymeric sensors useful for healthcare-related application fields, such as the sensitive detection of biomolecules and cellular interfacing. Within the well-established field of biomedical polymeric sensors, surface modification and/or functionalization using plasma is just emerging as a technology to improve selectivity and sensitivity in the biodetection process. Treatments based on plasma irradiation of polymer surfaces, which have been traditionally applied for cleaning, etching, activating or cross-linking, are currently being used to induce the formation of electrocatalytic species able to promote the oxidation of, for example, bioanalytes and/or gas molecules harmful for human health. Here, we summarize the main advances in the utilization of plasma technologies for the fabrication of polymeric sensors for advanced biomedical applications (e.g. humidity, temperature, pH, neurotransmitter, and glucose sensors).

Aptamer-Based Carboxyl-Terminated Nanocrystalline Diamond Sensing Arrays for Adenosine Triphosphate Detection.

Here, we propose simple diamond functionalization by carboxyl termination for adenosine triphosphate (ATP) detection by an aptamer. The high-sensitivity label-free aptamer sensor for ATP detection was fabricated on nanocrystalline diamond (NCD). Carboxyl termination of the NCD surface by vacuum ultraviolet excimer laser and fluorine termination of the background region as a passivated layer were investigated by X-ray photoelectron spectroscopy. Single strand DNA (amide modification) was used as the supporting biomolecule to immobilize into the diamond surface via carboxyl termination and become a double strand with aptamer. ATP detection by aptamer was observed as a 66% fluorescence signal intensity decrease of the hybridization intensity signal. The sensor operation was also investigated by the field-effect characteristics. The shift of the drain current-drain voltage characteristics was used as the indicator for detection of ATP. From the field-effect characteristics, the shift of the drain current-drain voltage was observed in the negative direction. The negative charge direction shows that the aptamer is capable of detecting ATP. The ability of the sensor to detect ATP was investigated by fabricating a field-effect transistor on the modified NCD surface.