Magnetic beads were used to quickly find bacteria in food and water
Researchers have developed a technology to analyze products and biological samples for pathogens using microscopic beads coated with antibodies.Engineers from the Massachusetts Institute of Technology used Dynabeads spherical magnetic polymers to perform the bacterial analysis. The scattered glow from the particles, recorded by a Romanov spectrometer, "gives away" the presence of pathogens. This method will help doctors quickly identify the source of infection and select a targeted antibiotic.
Dynabeads are tiny homogeneous particles made of a magnetic iron core and a polymer shell. Researchers apply antibodies sensitive to a given bacteria to the surface of the particles. When mixed with a liquid, such as blood or water, the target molecules are deposited on the Dynabeads. Using a magnet, scientists can gently attract the beads to the bottom of the vial and filter them out of solution.
The researchers found that the magnetic beads have a unique and strong Raman signature - a "fingerprint" of the molecule that shows how it scatters light. Detection of such a "signature" signals that a target pathogen is present in a sample.
The researchers tested the method to look for Salmonella bacteria in water. Infected water was mixed with Dynabeads coated with antibodies to this bacterium. The beads were then isolated on slides using magnets and examined under a microscope. In 0.5 s, the instrument examined the samples and detected a characteristic Raman signature.
"The analysis can be used to quickly give a positive or negative answer: are there impurities or not? Because even a few pathogens can cause clinical symptoms," Loza Tadesse, co-author of the study.
The proportion of pathogens in biological samples is small. To detect them under the microscope, crops are traditionally grown under favorable culturable conditions. This takes from a few days to several weeks.
The method proposed by the engineers shortens the analysis time for rapid diagnosis and initiation of targeted treatment, such as in cases of acute sepsis. The researchers are working on a portable test system for clinical laboratories.