According to the World Health Organization (WHO), every year food poisoning affects 600 million people worldwide -- almost 1 in every 10 people -- of which 420,000 die. Bacterial tests are conducted to detect food poisoning bacteria at food manufacturing factories, but it takes more than 48 hours to obtain results due to the time required for a bacteria incubation process called culturing. Therefore, there remains a demand for rapid testing methods to eliminate food poisoning accidents.

Responding to this need, the research team led by Professor Hiroshi Shiigi at the Graduate School of Engineering, Osaka Metropolitan University, utilized the optical properties of organic metal NHs -- composites consisting of polyaniline particles that encapsulate a large number of metal nanoparticles -- to rapidly and simultaneously identify food poisoning-inducing bacteria called enterohemorrhagicEscherichiacoli(E. coliO26 andE. coliO157) andStaphylococcus aureus。

团队首先发现,有机金属NHs名单ed stronger scattered light than metal nanoparticles of the same size. Since the scattered light of these NHs is stable in the air for a long period of time, they are expected to function as stable and highly sensitive labeling materials. Furthermore, it has been revealed that these NHs exhibit different colors of scattered light (white, red, and blue) depending on the metal elements of the nanoparticles (gold, silver, and copper).

Then the team introduced antibodies that bind specifically toE. coliO26,E. coliO157, andS. aureusinto the organic metal NHs and used these NHs as labels to evaluate the binding properties of the antibody-conjugated NHs to specific bacterial species. As a result,E. coliO26,E. coliO157, andS. aureuswere observed as white, red, and blue scattered light, respectively, under the microscope. Furthermore, when adding predetermined amounts ofE. coliO26,E. coliO157, andS. aureusto rotten meat samples containing various species of bacteria, the team succeeded in using these labels to simultaneously identify each bacterial species added.

This method can identify various types of bacteria by changing the antibodies to be introduced. In addition, since it does not require culturing, bacteria can be rapidly detected within one hour, increasing its practicality as a new testing method.

Shiigi教授评论说:“我们的目标是establish new detection principles and testing methods through the development of unique nano-biomaterials. Through this development, we hope to contribute not only to food safety and security, but also to the formation of a safe and affluent society in terms of stable supply and quality control of functional foods, medical care, drug discovery, and public health."