New sensitive strategy for formaldehyde sensing by in situ generation of luminescent silver nanoclusters

A new strategy for the detection of formaldehyde (FA) based on in situ generation of fluorescent silver nanoclusters (AgNCs) was demonstrated by using modified Tollens’ reagent. Tollens’ reagent is a reagent commonly used to distinguish between aldehyde and ketone functional groups. A silver mirror will be observed on a test tube surface if the sample contains aldehyde groups. However, in this method, the Tollens’ reagent was modified with polymethacrylic acid (PMAA), which acts as a template to generate fluorescent AgNCs instead of a silver mirror upon reaction with FA. In the presence of FA, Tollens’ reagent will be converted to AgNCs and the fluorescent emissions can be recorded. The fluorescence intensity of the generated AgNCs linearly increased as a function of the FA concentration. Parameters that may affect the detection sensitivity were studied and optimized. The proposed method has excellence selectivity for the detection of FA over other compounds. The proposed strategy exhibited a linear working concentration range of 1.0–9.0 μM with a detection limit of 0.14 μM and can be efficiently used to detect FA in bean sprout samples with a satisfactory accuracy. This proposed method does not require a complicated sensor probe preparation and enhances the FA detection selectivity and sensitivity.