Dipstick Technology Could Revolutionize Disease Diagnosis

Nucleic acid amplification is a powerful molecular biology tool, although its use outside the modern laboratory environment is limited due to the relatively cumbersome methods required to extract nucleic acids from biological samples.

Cellulose-based DNA binding is ideal for molecular diagnostics as it is inexpensive, portable, disposable, and easily modified. A nucleic acid purification method using cellulose paper that does not require any complex fabrication or specialized equipment such as pipettes and centrifuges has been developed.

Scientists at the University of Queensland (St. Lucia, Australia) investigated a variety of materials for their suitability for nucleic acid capture and purification. The team found that untreated cellulose-based paper can rapidly capture nucleic acids within seconds and retain them during a single washing step, while contaminants present in complex biological samples are quickly removed. Building on this knowledge, they have successfully created an equipment-free nucleic acid extraction dipstick methodology that can obtain amplification-ready DNA and RNA from plants, animals, and microbes from difficult biological samples such as blood in less than 30 seconds.

The investigators designed dipsticks made from Whatman No.1 with a small 8 mm2 DNA binding surface and a long water repellent handle made by impregnating the filter paper with Paraplast wax. Using these dipsticks, they developed an improved method in which all reagents can be prepared in advance and stored for a long period of time at room temperature. When needed, a nucleic acid extraction can be performed rapidly in three easy steps and less than 30 seconds without a pipette or any electrical device. To validate the newly developed nucleic acid purification method, they compared it with a popular commercial rapid paramagnetic bead DNA extraction method. They found that their method can purify amplifiable DNA significantly faster in less than 30 seconds for the new method versus 14.5 minutes for AMPure purification.

Jose Ramon Botella, PhD, a professor and senior author of the study said, “This technology will give people in developed and developing nations a new way of tackling a range of agricultural, health and environmental problems. Our dipsticks, combined with other technologies developed by our group, means the entire diagnostic process from sample collection to final result could be easily performed in a hospital, farm, hotel room or even a remote area such as a tropical jungle.” The study was published on November 21, 2017, in the journal Public Library of Science Biology.

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University of Queensland