Surface plasmon resonance-enhanced photothermal nanosensor for sensitive and selective visual detection of 2,4,6-trinitrotoluene

[Display omitted] •A novel nanosensor for selective detection of 2,4,6-trinitrotolune was fabricated.•A Meisenheimer complex was formed by means of a charge transfer process from AuNPs-NH2 to TNT, which promotes the aggregation of AuNPs-NH2, thus, enhance the photothermal performance.•The proposed sensor realized on-site visual and ultra-sensitive detection of TNT based on the induced photothermal effect. The exploration of feasible, reliable sensors for the selective and sensitive detection of nitroaromatic explosives is a critical issue nowadays as mandated by homeland security concerns. Our endeavor is to develop an instant on-site visual and ultra-sensitive photothermal nanosensor for 2,4,6-trinitrotoluene (TNT) detection, which could be applied on a broad scale with high selectivity and sensitivity. The fundamental principle of our work is that TNT could effectively induce the aggregation of the cysteamine-stabilized gold nanoparticles (Au NPs) by forming the Meisenheimer complex, which further enhanced the surface plasmon resonance (SPR) properties and the photothermal effects of Au NPs. Other coexisting nitroaromatics have negligible influences on the photothermal responses. By means of the temperature enhancement and photothermal imaging technique, the presence of TNT could be readily recognized and visualized, indicating wide potential applications in analytical sensing.