A Colorimetric Gold Nanoparticle Sensor To Interrogate Biomolecular Interactions in Real Time on a Surface

TLDR

The study introduces a label‑free optical biosensor that quantifies biomolecular interactions in real time on a surface using a commercially available UV‑visible spectrophotometer or optical scanner. It detects binding by monitoring changes in the absorbance spectrum of a self‑assembled monolayer of colloidal gold on glass as biomolecules attach to the immobilized colloids. The sensor achieves a 16 nM detection limit for streptavidin, is easy to fabricate, reproducible, requires only a UV‑visible spectrophotometer or optical scanner, and supports high‑throughput real‑time screening of biomolecular interactions.

Abstract

This paper presents a new label-free optical method to study biomolecular interactions in real time at the surface of an optically transparent substrate. The method relies on the change in the absorbance spectrum of a self-assembled monolayer of colloidal gold on glass, as a function of biomolecular binding to the surface of the immobilized colloids. Using this approach, we demonstrate proof of principle of a label-free optical biosensor to quantify biomolecular interactions in real time on a surface in a commercially available UV-visible spectrophotometer and of a colorimetric end-point assay using an optical scanner. The spectrophotometric sensor shows concentration-dependent binding and a detection limit of 16 nM for streptavidin. The sensor is easy to fabricate, is reproducible in its performance, has minimal technological requirements, namely, the availability of an UV-visible spectrophotometer or an optical scanner, and will enable high-throughput screening of biomolecular interactions in real time in an array-based format.