High contrast cleavage detection for enhancing porous silicon sensor sensitivity.

Using porous silicon (PSi) interferometer sensors, we show the first experimental implementation of the high contrast cleavage detection (HCCD) mechanism. HCCD makes use of dramatic optical signal amplification caused by cleavage of high-contrast nanoparticle labeled reporters instead of the capture of low-index biological molecules. An approximately 2 nm reflectance peak shift was detected after cleavage of DNA-quantum dot reporters from the PSi surface via exposure to a 12.5 nM DNase enzyme solution. This signal change is 20 times greater than the resolution of the spectrometer used for the interferometric measurements, and the interferometric measurements agree with the response predicted by simulations and fluorescence measurements. These proof of principle experiments show a clear path to achieving a real-time, highly sensitive readout for a broad range of biological diagnostic assays that generate a signal via nucleic acid cleavage triggered by specific molecular binding events.