CRISPR test leverages quantitative, colorimetric readout

2022 01 10 23 10 0651 Lab Test Tube Dna Blood 400

An international team of researchers is developing a novel biomarker diagnostic tool for noninfectious diseases that is easier to use than current tools and should expand this kind of testing worldwide.

Today's prevalent biomarker diagnostic tools that are based on RNA and DNA require controlled temperatures and involve a fairly complicated multi-tiered process. This latest test, dubbed CrisprZyme, can be used at room temperatures and is comparatively easy to use, leading to quicker and easier diagnoses.

The research team, led by Imperial College London and including researchers from MIT and Max Delbrück Center for Molecular Medicine in Berlin, believes that their new tool will be particularly applicable for surgeries carried out by general practitioners (GPs) in their offices and in developing countries with resource-limited clinics.

"As well as potentially boosting access to diagnostics in developing countries, this technology could bring us a step closer to personalized diagnostics at home or at the GP surgery," said Dr. Marta Broto in a prepared statement. "By making clinical diagnostic tests simpler, we will be able to provide clinicians with the right tools to test at the same GP surgery instead of having to reschedule for follow-up analyses and blood tests."

The tool, which is described in Nature Nanotechnology, builds on what are known as CRISPR (Clustered Regularly Interspaced Short Palindromic Repeats) diagnostic tests that use RNA to detect biomarkers in biological fluids, such as blood or urine. The key to this approach is that it amplifies the signal generated by RNA through multiple copying of the RNA to create a signal that is easier to detect.

To execute this multiple copying, CRISPR tests require controlled temperatures; expensive equipment is needed to maintain these temperatures. Even with this controlled environment, current CRISPR technologies are unable to tell us how much of a biomarker is present, limiting their effectiveness in monitoring noninfectious diseases such as cancer and heart disease.

The newly developed CrisprZyme technology does away with the traditional amplification approach of CRISPR tools and replaces it with colorimetric analysis. Since colorimetric analysis is capable of detecting the amount of biomarker present without the use of amplification, it eliminates the need for temperature control and additional steps.

"Our test, like others, indicates when a biomarker is present, but CrisprZyme is a simpler diagnostic than those currently available," said Molly Stevens, a professor at Imperial's Departments of Materials and Bioengineering. "What also sets it apart is that it can tell us just how much biomarker is present, which can help us not just with diagnosing a disease, but with monitoring its progress over time and in response to treatment."

The key to CrisprZyme providing information on the amount of biomarker present is the use of a nanoenzyme, a synthetic nanomaterial that behaves like an enzyme. It is the activity of this nanoenzyme that increases the signal of the RNA, making it easier for the colorimetric analysis to read.

The researchers concede that the CrisprZyme tool has not eliminated all additional steps in the process; the sample still needs to be treated with chemicals before the test is run. However, the researchers are looking for ways to possibly eliminate this step to make it even more user-friendly.

Stevens added: "Following further development and testing in the lab, we hope this could help take us a step closer to personalized medicine whereby treatment is tailored more specifically to patients' needs."

The group wrote that it has utilized the platform to identify patients with acute myocardial infarction and to monitor cellular differentiation in vitro and in tissue biopsies from prostate cancer patients.

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