"Bio-inspired Nanoeye" Localizes Potentiated Antibody Binding Capacity for Driving Salmonella typhimurium Detection

Salmonella enterica serovar typhimurium (S. typhimurium) is a ubiquitous foodborne bacterium that promises early diagnosis by lateral flow immunoassay (LFIA). To improve the sensitivity and selectivity of LFIA, the choice of nanomaterials affects the way the signal is output, the ability of the antibody to bind, and even the ultimate capability of the sensor. Therefore, we designed a "Bio-inspired Nanoeye" as a recognition element, which builds on the plasma effect with symmetric hollow morphology to achieve photothermal enhancement (η = 46.94%, |E/E₀| = 8.9). The high affinity of the gold nucleus significantly optimizes the antibody immobilization performance (Ortho-TPA: Te-Pt-Au), which binds to the immunizing antibody more stably, firmly, and rapidly (75 ns complete binding with a contact area of 25.64 nm², which has a 2.6-fold increase in binding area compared to that of Squint-TAP (Te-Au-Pt)), and dramatically enhances the target capturing ability. Based on the above advantages, the detection limits of Ortho-TPA-LFIA for S. typhimurium were 2752.12 (colorimetric (CM) mode) and 784.55 cfu mL^-1 (photothermal (PT) mode), which were 30.71-107.75-fold higher than those of AuNPs-LFIA. The excellent performance of Ortho-TPA and its stability, specificity, and recoveries in the LFIA application indicated that it is promising as an innovative solution for portable detection of foodborne pathogens.