Hinrichs, K.; Rappich, J.; Furchner, A.; Kratz, C.: IR microfluidics for in situ sensing of molecular interfaces. In: Israel Gannot, Katy Roodenko [Ed.] : Optical Fibers and Sensors for Medical Diagnostics, Treatment and Environmental Applications XXII : SPIE BIOS, 22 JANUARY - 28 FEBRUARY 2022Bellingham: SPIE, 2022 (Proceedings of SPIE ; 119530B), p. 119530B/1-6
10.1117/12.2608582
Abstract:
Recent developments in infrared (IR) microfluidics for sensitive monitoring of molecular adsorption at solid–liquid interfaces are briefly reviewed. A microfluidic platform is presented that uses a metallic island film for surface enhanced IR absorption (SEIRA) coupled to IR spectroscopies for bio-sensing and vibrational investigations of molecular monolayers and their adsorption kinetics. Exemplarily, IR spectral monitoring of the monolayer formation of 4-mercaptobenzonitrile (4-MBN) in liquid environment is discussed as a Langmuir isotherm. Adsorption isotherms of specific molecular vibrations are analyzed from the time-dependent evolution of band amplitudes and peak areas during adsorption. Given the detection limit of 0.03 nmol/cm2, the isotherms of 4-MBN, gluthathione (GSH) monolayer formation, and the sensing of 4-nitrobenzylmercaptan (4-NBM) by the MP/graphene surface are compared. Potential applications are bio- and bio-medical sensing as well as the study of processes, e. g., enzymatic reactions, chemical or catalytic reactions, receptor–ligand interactions, and structural changes of molecules due to environmental stimuli.