Novel microrobots detect lethal bacteria in 15 minutes

25 February 2019

A fluorescent magnetic spore-based microrobot has been developed to shorten the detection time.

Detecting bacterial infestations within the gastrointestinal system is often time-consuming and expensive. Clostridium difficile (C. difficile) is a particular threat that kills many frail patients. However, it can take up to two days for hospital laboratories to complete the current tests available for identifying the infection.

Seeking to address this limitation, Chinese University of Hong Kong researchers have developed fungi spore-inspired microrobots to detect C. difficile in stool samples within 15 minutes, without relying on expensive laboratory equipment. Their findings have been published in Science Advances.

C. difficile is the most common hospital-acquired enteric infection. The toxins secreted cause diarrhoea, fever and haematochezia (bleeding). In some cases, patients may develop severe peritonitis and sepsis.

In carrying out the study, Professor Joseph Sung (Croucher Senior Medical Research Fellowship, 2004, Croucher Fellowship, 1988), of the Faculty of Medicine, Chinese University of Hong Kong ,collaborated with Associate Professor Li Zhang, of the Department of Mechanical and Automation Engineering, to develop a fluorescent magnetic spore-based microrobot to shorten the detection time.

(It) allows doctors to give appropriate treatment and hospitals to carry out infection management measures in the earliest possible time, which can effectively prevent the spread of bacteria.

The technology relies on microrobots that feature fluorescent functionalised carbon nanodots. When the microrobots encounter toxins produced by C. difficile, the brightness of the fluorescence wanes, which can be detected with digital photographic equipment.

Within 15 minutes of being placed into stool samples infected by C. difficile the microbots no longer emit fluorescence. The researchers believe this rapid clinical sensing technique can supplement, or even replace, current detection methods.

The process is accelerated by the intricate three-dimensional architecture of the microrobot, which improves efficiency as it can move throughout a diluted stool sample and quickly come into contact with as many of the toxins present as possible. This “active” process also helps to detect low concentrations of toxins, according to the researchers.

With iron-based nanoparticles in their structure, the microrobots can be manipulated by an external magnetic field and gathered together for enhanced visualisation.

The researchers foresee that this new technology could be used for developing quick-sensing systems not only for C. difficile toxins, but for many bioanalytical fields, including those involving foods, chemicals, and early diagnosis of other bacterial diseases.

They now plan to construct an automated microrobotic platform for practical diagnostic applications in clinic and hospital settings and have applied to the Hong Kong government’s Innovation and Technology Fund for support for such development.

C. difficile is highly contagious and can be spread by contact with the excreta of infected people or contaminated surfaces. Sung said: “The development of a fast, accurate, simple and inexpensive test tool to shorten the diagnosis time allows doctors to give appropriate treatment and hospitals to carry out infection management measures in the earliest possible time, which can effectively prevent the spread of bacteria.”

Professor Joseph J.Y. Sung is Professor of Medicine in the Department of Medicine, Chinese University of Hong Kong, and a former Vice-Chancellor and President of the university. His key research interests are colorectal cancer, the microbiome and gastro-intestinal diseases, and gastro-intestinal bleeding. In 2008, he received the Laurel Award from the Prevent Cancer Foundation in the US for his work on cancer screening and prevention.

To view Prof Sung's Croucher profile, please click here