Using quantum dots and a smartphone to find killer bacteria:

A combination of off-the-shelf quantum dot nanotechnology and a smartphone camera soon could allow doctors to identify antibiotic-resistant bacteria in just 40 minutes, potentially saving patient lives. Rapid identification of MRSA is essential for effective treatment, but current methods make it a challenging process, even within well-equipped hospitals.

Researchers from Macquarie University and the University of New South Wales, both in Australia, have demonstrated a proof-of-concept device that uses bacterial DNA to identify the presence of Staphylococcus aureus positively in a patient sample -- and to determine if it will respond to frontline antibiotics. The research team reveals a new way to confirm the presence of the bacterium, using a mobile phone and some ultra-tiny semiconductor particles known as quantum dots. They using Synthetic Biology and NanoBiotechnology to address biomedical challenges. Rapid and simple ways of identifying the cause of infections and starting appropriate treatments are critical for treating patients effectively. The researchers' approach identifies the specific strain of golden staph by using a method called convective polymerase chain reaction (or cPCR). This is a derivative of a widely -employed technique in which a small segment of DNA has copied thousands of times, creating multiple samples suitable for testing. They subject the DNA copies to a process known as lateral flow immunoassay -- a paper-based diagnostic tool used to confirm the presence or absence of a target biomarker. The researchers use probes fitted with quantum dots to detect two unique genes, that confirm the presence of methicillin resistance in the golden staph. A chemical added at the PCR stage to the DNA tested makes the sample fluoresce when the genes are detected by the quantum dots -- a reaction that can be captured easily using the camera on a mobile phone. The result is a simple and rapid method of detecting the presence of the bacterium, while simultaneously ruling first-line treatment in or out. Although currently at the proof-of-concept stage, the researchers say their system which is powered by a simple battery is suitable for rapid detection in different settings.

 Source credit: Nano Magazine