The idea of inexpensive paper-based diagnostics isn’t new. But so far, these tests have relied on traditional chemistry like pregnancy tests do. Collins says his work now extends the idea to precisely engineered genetic reactions.
Each paper detection strip would cost only between 4 and 65 cents, and could be designed and produced in a day or so.
Collins showed the system could detect the Ebola virus, whose genetic code consists of RNA. When his team added bits of Ebola RNA to paper test strips, the genetic material completed a “circuit” allowing production of a protein which stained the paper, causing it to turn dark purple in about an hour.
Journal Cell - Paper-Based Synthetic Gene Networks
Using standard equipment at his lab bench and commercially–available, cell–free systems, Pardee designed and built a wide range of paper–based diagnostics and biosensors. He also used commonly–used fluorescent and color–changing proteins to provide visible indication that the mechanisms were working. Once built, the paper–based tools can be freeze dried for safe room–temperature storage and shipping, maintaining their effectiveness for up to one year. To be activated, the freeze–dried paper need simply be rehydrated with water.
•A stable, sterile, and abiotic paper-based platform for synthetic biology
•Enables rapid prototyping for cell-based research and gene circuit design
•Extends laboratory capabilities out of the lab and into the field
•Small-molecule and RNA sensors, including strain-specific Ebola virus sensors
Synthetic gene networks have wide-ranging uses in reprogramming and rewiring organisms. To date, there has not been a way to harness the vast potential of these networks beyond the constraints of a laboratory or in vivo environment. Here, we present an in vitro paper-based platform that provides an alternate, versatile venue for synthetic biologists to operate and a much-needed medium for the safe deployment of engineered gene circuits beyond the lab. Commercially available cell-free systems are freeze dried onto paper, enabling the inexpensive, sterile, and abiotic distribution of synthetic-biology-based technologies for the clinic, global health, industry, research, and education. For field use, we create circuits with colorimetric outputs for detection by eye and fabricate a low-cost, electronic optical interface. We demonstrate this technology with small-molecule and RNA actuation of genetic switches, rapid prototyping of complex gene circuits, and programmable in vitro diagnostics, including glucose sensors and strain-specific Ebola virus sensors.
SOURCES- Harvard, Technology Review, Journal Cell, Vimeo