Point-of-care-ready nanoscale ISFET arrays for sub-picomolar detection of cytokines in cell cultures

Rapid and frequent screening of cytokines as immunomodulation agents is necessary for precise interventions in severe pathophysiological conditions. In addition to high-sensitivity detection of such analytes in complex biological fluids such as blood, saliva, and cell culture medium samples, it is also crucial to work out miniaturized bioanalytical platforms with potential for high-density integration enabling screening of multiple analytes. In this work, we show a compact, point-of-care-ready bioanalytical platform for screening of cytokines such as interleukin-4 (IL-4) and interleukin-2 (IL-2) based on one-dimensional ion-sensitive field-effect transistors arrays (nanoISFETs) of silicon fabricated at wafer-scale via nanoimprint lithography. The nanoISFETs biofunctionalized with receptor proteins alpha IL-4 and alpha IL-2 were deployed for screening cytokine secretion in mouse T helper cell differentiation culture media, respectively. Our nanoISFETs showed robust sensor signals for specific molecular binding and can be readily deployed for real-time screening of cytokines. Quantitative analyses of the nanoISFET-based bioanalytical platform was carried out for IL-4 concentrations ranging from 25 fg/mL (1.92 fM) to 2.5 μg/mL (192 nM), showing a limit of detection down to 3-5 fM, which was found to be in agreement with ELISA results in determining IL-4 concentrations directly in complex cell culture media. Graphical abstract.