Synthetic Polymers to Counter Chemical and Biological Threats | SRI International

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Synthetic Polymers to Counter Chemical and Biological Threats

SRI has been awarded a $10 million contract under a DARPA program to reimagine how proteins are constructed and to develop novel medicines and diagnostics as threat countermeasures.

By reimagining how proteins are constructed, SRI Biosciences will develop novel molecules that could be used to create countermeasures to chemical and biological threats against U.S. forces.

The work is being performed as part of DARPA’s Folded Non-Natural Polymers with Biological Function program, known as Fold F(x). The program’s initial goal is to develop biologically active non-natural polymers that are structurally similar to naturally occurring proteins. These polymers should be able to detect or neutralize identified chemical or biological threats. Once potent molecules are found, they could be produced at mass scale and give Department of Defense medical researchers new tools to develop medicines, sensors, and diagnostics.

To develop the new polymers, SRI Biosciences will combine its expertise in biopolymer design and synthesis and medicinal chemistry with a breakthrough approach to screening vast numbers of compounds. SRI’s compound screening innovation is based on its proprietary Fiber-Optic Array Scanning Technology (FAST). Currently the highest-throughput screening platform available, FAST can screen 25 million compounds in just one minute.

Initially developed to identify circulating tumor cells in a blood sample, FAST can distinguish a single tumor cell among tens of millions of healthy ones in a few minutes. With DARPA support, SRI will expand its proprietary screening method to test individual compounds attached to beads that are similar in size to tumor cells.

The overall goal of the Fold F(x) program is to expand on the utility of proteins and overcome their limitations by re-engineering their polymer backbone using rational design—i.e., creating new molecules with a particular functionality. Since most biopolymers are sensitive to heat denaturation and chemical degradation, their shelf life is limited. The alternative to rational design is to synthesize enormous libraries of non-natural polymers in the hope that combinations will have a desired action. Finding a single effective compound, such as one that can block a virus, requires screening hundreds of millions of compounds.

As a proof of concept, the SRI team will design, synthesize, and screen chemically unique libraries of 100 million non-natural polymers for activity against a variety of biological agents and chemical agents, including deadly toxins such as ricin and highly pathogenic viruses such as the H1N1 bird flu strain.

As the program evolves, it may progress to include a range of possibilities, such as how to synthesize molecules to fold so that they emit light, have enhanced levels of strength or elasticity, or store power.