Light-directed functionalization methods for high-resolution optical fiber based biosensors

Abstract

Recent advances in miniaturization and analyte-sensitive fluorescent indicators make optical fiber biosensors promising alternatives to microelectrodes. Optical sensing offers several advantages over electrochemical methods including increased stability and better spatial control to monitor physiological processes at cellular resolutions. The distal end of an optical fiber can be functionalized with different fluorophore/polymer combinations through mechanical, dip-coating or photopolymerization techniques. Unlike mechanical and dip-coating schemes, photopolymerization can spatially confine the sensing layer in the vicinity of light in a more reproducible and controllable manner. The objective of this study was to fabricate microscale fluorescence lifetime based optrodes using UV-induced photopolymerization. Six commercially available acrylate based monomers were investigated for stable entrapment of the oxygen sensitive porphyrin dye (PtTFPP) dye via photopolymerization at the end of optical fibers. Of these, the acrylate-functionalized alkoxysilane monomer, 3-methacryloxypropyl-trimethoxysilane (tradename Dynasylan MEMO) showed maximal response to changes in oxygen concentration. Dye-doped polymer microtips were grown at the ends 50 μm optical fibers and sensitivity and response time were optimized by varying both the concentration of doped dye and the excitation power used for polymerization. The resulting sensors showed linear response within the physiologically relevant range of oxygen concentrations and fast response times. While applied here to oxygen sensing, the photopolymer formulation and process parameters described are compatible with a wide range of available organic dyes and can be used to pattern arrays of spots, needles or more complex shapes at high spatial resolution.

Fiber-Optic Chemical Sensors and Fiber-Optic Bio-Sensors

“…Nevertheless, the sensitivity, durability and the dynamic range of developed sensors meet the demands for the determination of remnants of glucose in diet beverages and the control of lower glucose content in bioreactors. UV-cured polymers were applied also in preparation of microscale fluorescence lifetime based optrodes, which showed linear response within the physiologically relevant range of oxygen concentrations as well as fast response times [ 133 ].…”

Active Micro-Nano-Collaborative Bioelectronic Device for Advanced Electrophysiological Recording

“…Furthermore, the irreparable harm to the cells and the intricate manipulation process do not facilitate the recording of multiple cells for a long period simultaneously [18][19][20][21][22][23][24]. Voltage-sensitive dye-based methods can record multiple cells simultaneously but are plagued by issues, such as low SNR, phototoxicity, and limited temporal resolution [25][26][27][28][29][30]. Therefore, several scalable methods for electrophysiological signal recording have been explored, including passive electrodes [31][32][33][34][35][36][37] and active micro/nanobioelectronic devices [38][39][40][41][42][43][44][45][46].…”