Characterization of SPAD Array for Multifocal High-Content Screening Applications

Anthony Tsikouras,Pietro Peronio,Nehad Hirmiz,M Deen,Ivan Rech,Qiyin Fang

doi:10.3390/photonics3040056

Abstract

Current instruments used to detect specific protein-protein interactions in live cells for applications in high-content screening (HCS) are limited by the time required to measure the lifetime. Here, a 32 × 1 single-photon avalanche diode (SPAD) array was explored as a detector for fluorescence lifetime imaging (FLIM) in HCS. Device parameters and characterization results were interpreted in the context of the application to determine if the SPAD array could satisfy the requirements of HCS-FLIM. Fluorescence lifetime measurements were performed using a known fluorescence standard; and the recovered fluorescence lifetime matched literature reported values. The design of a theoretical 32 × 32 SPAD array was also considered as a detector for a multi-point confocal scanning microscope.

Highlights

In drug discovery, one of the most time-consuming stages is the identification of candidate drugs
We explored the possibility of implementing a custom-made single-photon avalanche diode (SPAD) array with an integrated Time-correlated single-photon counting (TCSPC) chip for high-content screening (HCS) fluorescence lifetime imaging (FLIM)
With the capability of multiplexing confocal and two-photon FLIM, SPAD array technology could make it feasible to apply FLIM-Förster resonance energy transfer (FRET) protein-protein interaction studies to the realm of HCS. This would be a major advance for the drug discovery process

Summary

Introduction

One of the most time-consuming stages is the identification of candidate drugs. Whether it is two proteins binding to each other or multiple proteins forming an oligomer, these protein-protein interactions happen at the scale of a few nanometers: far below the optical diffraction limit Such interactions are invisible in morphological high-content screening. Such techniques use existing information of these interactions, as well as their biological pathways, to enable a better understanding of how the drug works, as well as the side effects. One such directed approach is to use Förster resonance energy transfer (FRET), which offers the Photonics 2016, 3, 56; doi:10.3390/photonics3040056 www.mdpi.com/journal/photonics

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Conclusion