Surface Biochemical Modification of Poly(dimethylsiloxane) for Specific Immune Cytokine Response

Recent evidence suggests that proinflammatory cytokines, such as tumor necrosis factor alpha (TNF-alpha), play a pivotal role in the development of inflammatory-related pathologies (covid-19, depressive disorders, sepsis, cancer, etc.,). More importantly, the development of TNF-alpha biosensors applied to biological fluids (e.g. sweat) could offer non-invasive solutions for the continuous monitoring of these disorders, in particular, polydimethyisidoxane (PDMS)-based biosensors. We have therefore investigated the biofunctionalization of PDMS surfaces using a silanization reaction with 3-aminopropyltriethoxysilane, for the development of a human TNF-alpha biosensor. The silanization conditions for 50 mu m PDMS surfaces were extensively studied by using water contact angle measurements, electron dispersive X-ray and Fourier transform infrared spectroscopies, and fluorescamine detection. Evaluation of the wettability of the silanized surfaces and the Si/C ratio pointed out to the optimal silanization conditions supporting the formation of a stable and reproducible aminosilane layer, necessary for further bioconjugation. An ELISA-type immunoassay was then successfully performed for the detection and quantification of human TNF-alpha through fluorescent microscopy, reaching a limit of detection of 0.55 mu g/mL (31.6 nM). Finally, this study reports for the first time a promising method for the development of PDMS-based biosensors for the detection of TNF-alpha, using a quick, stable, and simple biofunctionalization process.