Capacitive biosensors for ultra-sensitive assays

• Capacitive biosensors show increased sensitivity and stability when current pulses are used instead of the potential used thus far.
• Microcontact imprinting yields highly sensitive sensor chips with high stability.
• Sensor chips with antibodies can be reused several times.
• Single-stranded DNA (ss-DNA) oligos are used to detect genes of resistance in sensitive assays of multiresistant bacteria.

Capacitive binding assays have long been considered highly sensitive. The underlying method in such assays includes sending short potential pulses and then registering the current. However, with the introduction of current pulses and registration of potential responses, the stability improved significantly, leading to assays of extreme sensitivities. The new assaying technology has been applied in a range of affinity binding assays, from immunoassays via DNA base pairing to the use of molecularly imprinted polymers (MIPs). Overall, very good sensitivities have been recorded, and the MIPs exhibit high stability and reusability.