Label-Free Optical\nBiosensors Based on Aptamer-Functionalized\nPorous Silicon Scaffolds

Abstract

A proof-of-concept\nfor a label-free and reagentless optical biosensing\nplatform based on nanostructured porous silicon (PSi) and aptamers\nis presented in this work. Aptamers are oligonucleotides (single-stranded\nDNA or RNA) that can bind their targets with high affinity and specificity,\nmaking them excellent recognition elements for biosensor design. Here\nwe describe the fabrication and characterization of aptamer-conjugated\nPSi biosensors, where a previously characterized his-tag binding aptamer\n(6H7) is used as model system. Exposure of the aptamer-functionalized\nPSi to the target proteins as well as to complex fluids (i.e., bacteria\nlysates containing target proteins) results in robust and well-defined\nchanges in the PSi optical interference spectrum, ascribed to specific\naptamer-protein binding events occurring within the nanoscale pores,\nmonitored in real time. The biosensors show exceptional stability\nand can be easily regenerated by a short rinsing step for multiple\nbiosensing analyses. This proof-of-concept study demonstrates the\npossibility of designing highly stable and specific label-free optical\nPSi biosensors, employing aptamers as capture probes, holding immense\npotential for application in detection of a broad range of targets,\nin a simple yet reliable manner.