• Traditional methods for detecting trinitrotoluene (TNT) may have challenges in spotting tiny amounts of explosives or mistakenly flag other substances as explosives. False alarms can cause needless chaos and evacuations.
• Some current detection approaches could be sluggish and time taking. They could also rely on intricate and expensive gear – not great for widespread use.
• Regular security methods could be easily bypassed by terrorists using TNT-based explosives. Also, after explosive incidents, effective cleaning is very important.
• Some TNT detection methods might not work in many places. Bulky & stationary TNT detection methods are often not practical.
• These issues were taken into consideration previously but no proper method was identified. The present patent discloses a noble method for selective visual detection of TNT, addressing above mentioned issues.

The instant patent discloses a method for selective identification (visual detection) of 2,4,6-trinitro-toluene (TNT), comprises:

• 2 mg of Au MFs dispersed in 10 mL isopropanol, 1.5 mL ammonia solution, & 120 µL tetraethyl olihosilicate (TEOS) was added under rapid stirring for 1h to form Au@SiO2.

• The fluorescein isothiocyanate (FITC) added prior to addition of TEOS with Au@SiO2 MFs results in the formation of Au@SiO2-FITC MF.

• 1 mL of a fifteen atom anchored silver clusters (Ag15), embedded in bovine serum albumin (BSA) added with 2 mg of silica-coated Au MF dispersed in 1 mL distilled water, 0.5 mL 3-amino-propyl-trimethoxysilane (APTMS) & incubated for 30min resulting in Au@SiO2-FITC @Ag15 MFs formation.

• varying concentrations of TNT is exposed to Au@(SiO2-FITC)@Ag15 MFs.

Characterized in that, exposure of TNT to Au@(SiO2-FITC)@Ag15 MFs decreases its luminescence intensity significantly while optical image remains unaffected, wherein green emission of FITC from the particle as the red luminescence from the cluster was quenched completely was observed under visible & UV light. Wherein:

• The quenching of cluster luminescence is due to the formation of a Meisenheimer complex by the chemical interaction between TNT & free amino groups in BSA.
• 15 atom silver cluster protected with BSA is red luminescent water soluble quantum cluster (QC); wherein silver clusters exhibits high quantum yield (10.7%) in water, it is stable in a wide pH range & exhibits emission in solid state.
• Au@(SiO2-FITC)@Ag15 MFs after further functionalization with Ag QCs, shows red & green emission of FITC is suppressed.
• Colour of the solution turns dark red & the formation of complex was confirmed by emergence of features at 340, 450 and 525 nm in UV absorption spectra.
• Specificity of Meisenheimer complexation makes cluster selective to TNT and closely similar molecules do not quench its luminescence.
• Disappearance of the luminescence of Ag15 on MF and simultaneous appearance of luminescence of another embedded fluorophore can be used for easy identification of analyte.