This portable device enables on-site pathogen detection in water. Contamination of water sources by various biological or nonbiological contaminants constitutes global public health concerns. Pathogens are rapidly introduced in water and can enter the human body directly and indirectly. Every year, approximately 1.6 million people worldwide, in countries of all economic levels, die due to waterborne diseases. The prominent source of disease-causing agents in water is fecal pollution, including bacteria present in fecal matter from humans and warmed-blooded animals. Coliform bacteria, specifically E. coli, is a prime indicator of fecal contamination in freshwater since they are present in the intestines of humans and warm-blooded animals. Monitoring the presence of pathogens in recreational and drinking water sources is crucial to prevent people from contracting these diseases.
Currently, there are accurate and sensitive laboratory assays to detect pathogens in water, mostly involving culturing of samples and separation/filtration strategies. However, they require costly and bulky tools and trained personnel. Additionally, the turnaround times are too long due to microbial culturing. There is a growing trend to develop small, cost-effective, on-site platforms for more repaid results. However, they also present limitations, such as low sample volumes, long incubation times, and high detection limits. On the contrary, nucleic acid amplification tests provide low detection limits and faster turnaround times. However, some of them, such as PCR-based tests, require trained personnel and sample preparation.
Researchers at the University of Florida have developed an on-site portable platform for rapid and cost-effective detection of pathogens in water involving isothermal nucleic acid amplification. This platform, with a rotating valve design, accepts larger volumes of liquid and integrates all the necessary sample preparation steps for a nucleic acid assay, shortening the assay time and eliminating the need for trained personnel.
Portable platform for on-site, rapid, and cost-effective pathogen detection in environmental water samples
This portable, handheld device enables on-site detection of pathogens in environmental water samples. It integrates all the necessary steps for a nucleic acid assay, including cell lysis, nucleic acid enrichment and purification, amplification, and detection. The device consists of a buffer unit containing multiple buffer wells with a ball valve at the bottom of each well. This unit sits above a mixing unit, including a mixing well and a pin, with the ability to rotate to align with each buffer well. When the mixing unit aligns with a buffer well, the pin engages with the ball-based valve to release the buffer from the buffer well into the mixing well. The mixing unit further contains a drain connecting to a detection unit on its bottom.
This detection unit includes a well containing an absorbent layer for enrichment of the nucleic acid, such as chromatography paper, cellulose paper, a membrane, or glass microfiber paper. After nucleic acid concentration, amplification of DNA by loop-mediated isothermal amplification (LAMP) or RNA by reverse transcription LAMP (RT-LAMP) takes place by connecting the device to a portable heat source. This heat source is a battery-powered coffee mug functioning as a water bath to provide a constant temperature or other alternatives. Subsequent detection of pathogens involves turbidity measurement or colorimetric detection by the naked eye or a smartphone camera. All the wells contain the necessary buffers and reagents for each step, including lysis, binding and wash buffers, and LAMP and RT-LAMP mixes.