A Simple Colorimetric Au‐on‐Au Tip Sensor with a New Functional Nucleic Acid Probe for Food‐borne Pathogen Salmonella typhimurium

An Au-on-Au tip sensor is developed for the detection of Salmonella typhimurium (Salmonella), using a new synthetic nucleic acid probe (NAP) as linker immobilization DNA-conjugated Au nanoparticle (AuNP) onto DNA-attached thin layer inside pipette tip. In presence Salmonella, RNase H2 from (STH2) cleaves NAP and freed AuNP can be visually detected by paper strip. This portable biosensor does not require any electronic, electrochemical or optical equipment. It delivers limit 3.2×103 CFU mL−1 in 1 h without cell-culturing signal amplification show cross-reactivity with several control bacteria. Further, reliably detects spiked food samples, such ground beef chicken, milk, eggs. The reused stable at ambient temperature, showing its potential point-of-need device prevention poisoning Salmonella.