Supplement 1: Pupil function engineering for enhanced nanoparticle visibility in wide-field interferometric microscopy

Originally published in Optica on 20 February 2017 (optica-4-2-247

Label-Free and High-Throughput Detection of Biomolecular Interactions Using a Flatbed Scanner Biosensor

Fluorescence based microarray detection systems provide sensitive measurements; however, variation of probe immobilization and poor repeatability negatively affect the final readout, and thus quantification capability of these systems. Here, we demonstrate a label-free and high-throughput optical biosensor that can be utilized for calibration of fluorescence microarrays. The sensor employs a commercial flatbed scanner, and we demonstrate transformation of this low cost (∼100 USD) system into an Interferometric Reflectance Imaging Sensor through hardware and software modifications. Using this sensor, we report detection of DNA hybridization and DNA directed antibody immobilization on label-free microarrays with a noise floor of ∼30 pg/mm², and a scan speed of 5 s (50 s for 10 frames averaged) for a 2 mm × 2 mm area. This novel system may be used as a standalone label-free sensor especially in low-resource settings, as well as for quality control and calibration of microarrays in existing fluorescence-based DNA and protein detection platforms