Microfluidic paper-based colorimetric chemo-sensing of formaldehyde using tetramethylbenzidine-conjugated gold nanoflowers: A point-on-demand approach for efficient chemosensing of volatile organic compounds

Abstract

The presence of formaldehyde, a common environmental aldehyde and a recognized carcinogen, poses a significant health risk to humans. Monitoring its levels in environmental samples and human biofluids is crucial for both pollution control and advancements in health science. This study introduces an effective colorimetric method utilizing UV–Vis spectroscopy to identify formaldehyde in real samples. Various types of gold nanoparticles (AuNPs) with diverse sizes and structures were employed to develop a photochemical chemosensing device. The method exhibited high sensitivity in detecting formaldehyde, particularly through the use of gold nanoflowers (AuNFs) at a pH of 6.15, with a low quantification limit of 0.1 µM and a linear range of 0.6 µM to 1 M. Furthermore, the method was successfully utilized to assess formaldehyde in human biofluids. Additionally, a paper-based microfluidic colorimetric opto-device was incorporated for on-site and on-demand formaldehyde screening. This study showcases the application of AuNPs for the precise and sensitive detection of formaldehyde in human biofluids, offering potential for advanced analytical methods targeted at formaldehyde and other volatile organic compounds (VOCs). The practicality, affordability, and portability of the microfluidic paper-based colorimetric device (µPCDs) make it a promising choice for point-of-care VOC testing. This represents the first demonstration of µPCDs for the selective photochemical sensing of toxic substances, and its one-step process that does not rely on novel sorbents, membranes, or external stimuli, making it easily scalable. The potential for µPCDs to be broadly applicable to the selective monitoring of formaldehyde from complex bio-matrices is evident. This method demonstrated robust performance in terms of accuracy, sensitivity, reproducibility, and selectivity.