Fabrication of flexible AuNPs@ polyimide heating chips for in situ explosives SERS sensing in nature samples

In this study, highly sensitive flexible AuNPs@ polyimide SERS heating chips (APHC) were fabricated for in situ collecting and detecting TNT. Large-scale AuNPs arrays were synthesized by liquid-liquid interface self-assembly and transferred to polyimide heating film as SERS substrates. 4-ATP and AgNPs functionalized on APHC were used as capture means and signal amplifiers, combining with TNT to form the AuNPs-TNT-AgNPs “sandwich” structure. This flexible APHC chip showed high sensitivity as enhancement factor was 5.5×10⁵, and good repeatability and stability (RSD<10%). It was applied to detect TNT solutions with a low concentration of 10⁻⁹ M, and showed a good linear response in the range from 10⁻⁵ to 10⁻⁹ M (R² = 0.986). In addition, the detection method also had good selectivity and no response to various TNT analogs. More important, combing with the thermal enrichment strategy, TNT dispersed in environmental samples such as soil, fruit and clothing would be enriched as vapor then collected and detected by APHC. This APHC device shows great potential for in situ sensing platforms, due to its sensitivity, high efficiency, and excellent portability.