Gold nanoparticle-based redox signal enhancement towards the detection of single bacterium

In this work, we report a portable microfluidic chip based on gold nanoparticle-enhanced electrochemical detection for single-bacteria diognostic. The possibility of single-bacteria detection is realized here by using electroactive molecules modified on gold nanoparticles (NPs) to detect and differentiate Staphylococcus aureus and Pseudomonas aeruginosa. The detection limit of these two electroactive molecules is near femtomolar (1 pM) when immobilized on gold nanoparticles (NPs), and the minima amounts of gold NPs required in the detection is around thousands (10³ particle/μl). A concentration of couples whole bacteria (<;10 cells/μl) is detected by CV measurements. The liner detection limit concention is form 1-1000 cells/μl. The results showed that the portable biochip system has great potential as a device for single-particle or possibly even single-organism detection.