Colorimetric and dynamic light scattering dual-readout assay for formaldehyde detection based on the hybridization chain reaction and gold nanoparticles

Abstract

Formaldehyde (FA), as one of the largest indoor pollutants, can induce adverse health impacts and even cause various diseases. Therefore, it is necessary to establish a sensitive detection method for the determination of trace FA in the environment. Herein, a novel colorimetric and dynamic light scattering (DLS) dual-readout assay for FA detection is developed based on the hybridization chain reaction (HCR) and gold nanoparticles (AuNPs). In the presence of FA, Ag⁺ ions bound by the DNA hairpin structure (HP) are reduced, and then the opened HP acts as an initiator to trigger the HCR process. The HCR products can induce the assembly of AuNPs via DNA hybridization, resulting in a sharp color change recorded using a smartphone camera and a significant increase in the diameter measured by DLS. The developed colorimetric sensor can detect FA as low as 20 μg L⁻¹ through a smartphone application. Meanwhile, the DLS sensing strategy allows the determination of FA with a detection limit of 1.0 μg L⁻¹. Moreover, the proposed method shows excellent selectivity and acceptable applicability for the determination of FA in air, which might hold great application potential in environmental monitoring.