Release date: 2013-05-09
Researchers at the Massachusetts General Hospital (MGH) have pioneered the development of portable cancer diagnostic devices, and now they are making new advances in rapid diagnostic techniques for tuberculosis and other important infectious diseases. The researchers published research results in Nature Communication and Nature Nanotechnology. The device combines microfluidics and nuclear magnetic resonance (NMR) techniques to diagnose not only these important infectious diseases, but also whether they exist. Antibiotic resistant strain.
Dr. Ralph Whistler, co-author of the two papers and MGH chief physician, said that rapid identification of pathogens associated with infectious diseases and testing for drug resistance is essential for diagnosing diseases and deciding whether to use antibiotics for patients. important. The new method takes only two to three hours to complete the above process, which is a significant improvement over the standard culture method that takes two weeks to provide diagnostic results.
MGH researchers have in the past developed portable devices that can detect cancer biomarkers in blood (or very small tissue samples). The target cells or molecules are first labeled by magnetic nanoparticles, and the sample is then passed through a micro NMR system that detects and quantifies the magnitude of the target. However, there is a problem in that it is difficult to find antibodies when the system is used for bacterial diagnosis. In early studies, antibodies were often used to accurately detect specific bacteria. As a result, the research team turned to targeting specific nucleic acid sequences.
The new device described in the April 23 issue of Nature Communication can detect the DNA (deoxyribonucleic acid) of tuberculosis in a small amount of sputum specimens. After the DNA is extracted from the sample, the target sequence is amplified using standard procedures and then captured by polymer beads containing complementary nucleic acid sequences and by magnetic nanoparticles whose sequence can bind to other parts of the target DNA. mark. By incorporating a micro NMR coil into the device, any tuberculosis DNA present in the sample can be detected.
Tests on control samples from tuberculosis patients and healthy populations showed that the device detected all positive samples in less than 3 hours with a false positive rate of zero. The existing diagnostic process takes several weeks and the false negative rate is as high as 40%.
The researchers described a similar new technology on May 5th, Nature and Nanotechnology. This system targets ribosomal RNA (rRNA) as a marker for nanoparticles. The common nucleic acid probes developed by the researchers were able to detect rRNA regions shared by many bacterial populations, and another set of probes targeted specific sequences of 13 clinically important important pathogens, including Streptococcus pneumoniae and large intestines. Helicobacter and methicillin-resistant Staphylococcus aureus (MRSA).
The device is very sensitive and can detect only one or two bacteria in a 10 ml blood sample to accurately determine the bacterial load. Tests on blood samples from infected patients showed that the system accurately identified specific bacterial species in less than two hours and found two bacterial species that could not be detected by standard culture techniques.
Whistler said that the detection of pathogens based on magnetic interactions is a very reliable method that does not require the quality of the sample, which means that extensive purification measures in a limited resource environment will no longer be necessary. Moreover, bacteria can be detected within a few hours, which is crucial for controlling the spread of tuberculosis.
Source: China Science and Technology Network
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