A plastic total internal reflection photoluminescence device for enzymatic biosensing

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 (H 2 O 2 ) biosensor incorporating catalase was fabricated on the TIRPh platform without photolithography or etching. The O 2 -sensitive phosphorescence of Ru(dpp) 3 was used as a transduction mechanism and catalase was used as a biocomponent for sensing. The H 2 O 2 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. An easily fabricated, plastic, total internal reflection photoluminescence (TIRPh) platform for enzymatic biosensing does not require an optical filter.