Find a needle in a haystack
Silicon will help to find dangerous pathogens in human blood
ChemPort.Ru based on Chemistry World: Silicon chip spots dangerous pathogens in human bloodResearchers from China have developed silicon chips doped with silver nanoparticles that can quickly identify various pathogens in blood samples.
The new technique is a fast and cheap alternative to existing diagnostic methods.
Recently, the medical community has expressed growing concern about the emergence of resistant pathogens, which, if not developed ways to combat them, by 2050 could cause the premature death of 300 million people. Given that only one new class of substances with potentially antimicrobial activity has been discovered over the past quarter century, many research groups are currently trying to develop new diagnostic approaches that can prevent a global health crisis.
The head of the new study, Yao He, notes that the rapid, selective and cheap detection of various pathogenic bacteria in clinical samples is an important element in preventing many serious diseases caused by bacterial infections. Despite the fact that several new pathogen detection methods are already available, they are not yet able to solve the main task – to provide a quick diagnosis.
He explains that complex biochemical analysis is time-consuming and can suffer from relatively low sensitivity. Surface-enhanced Raman scattering spectroscopy (SERS) can solve these problems. SERS spectroscopy can distinguish molecules by analyzing how they reflect photons, and such reflection is individual for each substance, like fingerprints.
In recent years, raman spectroscopy has been successfully used several times in clinical studies, however, according to He, the possibilities of the method are still limited – for use in real diagnostics, it is necessary that the SERS method can detect bacteria in clinical samples, and for this it is necessary to create a highly efficient multifunctional platform.
He and his colleagues managed to create such a platform by introducing silver nanoparticles into a silicon wafer. In order for such a substrate to be used to detect a number of bacteria, silicon wafers were modified by grafting fragments of 4-mercaptophenylboronic acid, a common agent for binding bacteria, to the surface.
Human blood with Escherichia coli or Staphylococcus aureus bacteria was applied to the obtained plates of modified silicon and it was determined whether SERS spectroscopy could distinguish between dangerous pathogens and the blood cells surrounding them. It was found that with the help of the developed substrate, SERS spectroscopy can detect both pathogens in quantities amounting to several hundred bacterial cells per milliliter of blood.
A drawing from an article by Wang et al. Simultaneous Capture, Detection, and Inactivation of Bacteria as Enabled
by a Surface-Enhanced Raman Scattering Multifunctional Chip (Angew. Chem. Int. Ed., March 27, 2015).
In the process of diagnosis, there was also a slow destruction of bacteria due to the gradual release of silver atoms from the surface of the substrate.
As Philip Howes of Imperial College London notes, what the new system does is like detecting a needle in a haystack – SERS copes with a very low concentration of target cells surrounded by a huge amount of interference. Howes emphasizes that the successful demonstration of the new technology on "infected" human blood makes it possible to talk about the significant potential of the possibility of using SERS in clinical diagnostics.
Portal "Eternal youth" http://vechnayamolodost.ru15.04.2015