Plasmonic nanohole arrays for monitoring growth of bacteria and antibiotic susceptibility test

Rapid and sensitive detections of the growth of bacteria are essential assay procedures in the food industry, water and environment control and clinical diagnosis. Here, we present a plasmonic nanohole sensor for rapid, sensitive and quantitative monitoring of the bacterial growth and antibiotic susceptibility test. The concept is based on extraordinary optical transmission (EOT) phenomenon in plasmonic nanohole and employs Escherichia coli specific antibody for bacteria capturing. The challenge lies in detecting the much larger dimension of E. coli with the smaller penetration depths of the electromagnetic field. The plasmonic nanohole array was fabricated using mask-based deep ultraviolet (DUV) lithography method and characterized for bulk refractive index sensitivity and surface mass sensitivity. After gold-specific surface modification and antibody immobilization, bacteria were effectively captured and grown on the sensor surface. The sensor platform with temperature-controlled environment was successfully tested for monitoring the growth of E. coli. The plasmonic nanohole sensor has immense potential for clinical diagnosis such as rapid determination of pathogen susceptibility test; with bulk refractive index sensitivity of 406.4 nm/RIU and surface mass sensitivity of ~1.802 ng/mm². We explored the capability of the sensor to provide sensitive monitoring of low bacterial quantity (<100 cells) and rapid detection within 2 h. Finally, the rapid antibiotic susceptibility test (AST) of E. coli was demonstrated with the plasmonic nanohole sensor.