Spectrally Filtered Photodiode Pairs For On-Chip Ratiometric Aptasensing Of Cytokine Dynamics

Miniaturized, cost-effective cytokine sensing devices are essential for health monitoring and critical care of patients with acute immune responses. Here we report an on-chip ratiometric aptasensing device to monitor the dynamics of an essential immune response biomarker, interferon-gamma. Our device is formed by pairs of spectrally filtered silicon photodiodes that are surface functionalized with aptamer probes. These photodiode pairs are able to rapidly detect two-color fluorescence changes transduced from aptamer-cytokine binding events within c.a. 6 min at picomolar levels, which are sufficient to capture the cytokine transients in point-of-care settings. Furthermore, our device can be reset to baseline by simple washing steps, yielding consistent readout in consecutive runs. Combined with their chip-scale construct and real-time operation, our cytokine sensors may have possible use in point-of-care and therapeutic screening applications.