Biomolecule detection in porous silicon based microcavities via europium luminescence enhancement

In this paper, we demonstrate the detection of europium-complex-labeled streptavidin in a porous silicon microcavity (pSiMC) via luminescence enhancement. The pSiMC platform was modified for optimized luminescence enhancement which encompassed changing the pore size of the microcavity to ensure molecular infiltration and adjusting the optical quality of the microcavity. Characterization of the optimized surface was performed by infrared spectroscopy, interferometric reflectance spectroscopy and luminescence measurements. Luminescence enhancement of the bound Eu(III) complex by a factor of 3 was observed on the optimized pSiMC as compared to that on a single pSi layer. The ability of a pSiMC to act as a luminescence enhancing sensor was confirmed using streptavidin as a model analyte on a biotin-modified pSiMC. The sensor was able to detect Eu(III) complex labeled streptavidin with a concentration as low as 150 nM. Furthermore, streptavidin was selectively detected when spiked in human wound fluid. The concept of detecting Eu(III) labeled bioconjugates on pSiMC may be incorporated into the design of highly sensitive and specific point-of-care biosensors.