Development of a microfluidic cell-based biosensor integrating a millisecond chemical pulse generator

The use of cell-based biosensors is usually limited by agonist-induced desensitization of cell-surface receptors. In this work, a microfluidic cell-based biosensor (μCBB) was developed for the detection of ATP in liquid environments. It consists of a millisecond chemical pulse generator for sample introduction in a pulsatile manner and a single NIH-3T3 cell expressing endogenous P2Y receptors as the sensing element. ATP solutions were used to simulate input signals for investigating the μCBB. By controlling negative pressures on two outlets of a cross-shaped microfluidic chip, pulses of ATP solutions were generated based on hydrodynamic gated injection. With ATP pulses of 100 ms every 50 s, the amplitude of the resulting calcium spikes maintained at a similar level, suggesting that the receptor desensitization was minimized. Consequently, the developed μCBB could be used for detecting pulsatile samples with extended use times. The sensitivity of the μCBB for detecting ATP was further determined and the cellular responses to millisecond ATP pulses were investigated in comparison to long-term stimulations.