A plastic total internal reflection photoluminescence device for enzymatic biosensing

Abstract

A total internal reflection photoluminescence (TIRPh) device employing an easily fabricated PMMA/PDMS waveguide system provides a detection limit comparable to the best reported results but without using an excitation filter. The optical mechanism is similar to total-internal-reflection-fluorescence (TIRF) but uses a ruthenium-based phosphorescent dye (Ru(dpp)₃) deposited on the PMMA core, motivating the generalized term of photoluminescence to include both fluorescence and phosphorescence. An enzymatic hydrogen peroxide (H₂O₂) biosensor incorporating catalase was fabricated on the TIRPh platform without photolithography or etching. The O₂-sensitive phosphorescence of Ru(dpp)₃ was used as a transduction mechanism and catalase was used as a biocomponent for sensing. The H₂O₂ sensor exhibits a phosphorescence to scattered excitation light ratio of 76 ± 10 without filtering. The unfiltered device demonstrates a detection limit of (2.2 ± 0.6) μM with a linear range of 0.1 mM to 20 mM. The device is the first total internal reflection photoluminescence based enzymatic biosensor platform, and is promising for cost-effective, low excitation interference, field-portable sensing.