Contamination detection tools integrate ultra-sensitive water testing with synthetic biology and nanotechnology

The platform, developed nearly 20 years ago, has been previously used to detect protein interactions with DNA, perform accurate COVID-19 tests, and has been reused to create highly sensitive water contamination detection tools.

The technology merges two exciting areas (synthetic biology and nanotechnology) to create a new platform for chemical monitoring. Once adjusted to detect different contaminants, the technology can detect up to 200 million and one part of metal lead and cadmium at concentrations, respectively, in minutes.

This paper was published this week in the Journal ACS Nano and represents research in multiple fields within Northwestern’s McCormick Engineering School.

This test was created by interfacing a synthetic biology biosensor with a nanomechanical microcanoic acid agent. The small cantilever is made of silicone and can be easily reproduced. When coated with a specially designed DNA molecule, a biosensing molecule called a transcription factor binds to the DNA and the cantilever bent. When exposed to a target chemical, the transcription factor biosensor is unbound, causing the cantilever to “slack off”. This can be measured accurately to detect chemicals.

The microcantilever technology was combined with the technique of Northwest synthetic biologist Julius Lac, who built and grew a cell-free biosensor that short for Rosalind (Ligand-induction-activated RNA output sensor). Its first model can sense 17 different contaminants using only one drop of water.

Rosalind technology is based on the same transcription factor biosensors configured to regulate gene expression in cell-free responses with binding and bound DNA.

During the coronavirus pandemic, Lucks saw microcantilever technology in the workplace when it was adapted by Professors Vinayak P. Dravid and Professor Gajendra Shekhawat to accurately detect SARS-Cov-2. Racking thought that coating these cantilevers with Lucks’ experimental DNA could potentially cause cantilevers to detect chemical toxins. By combining the components of the two tools, the McCormick duo, together with first author and postdoc Dilip Agarwal and graduate student Tyler Lucci, created an ultra-sensitive test of water contaminants.

“These are micro and nanosystems that don’t require a lot of viral materials to make a difference,” said Dravid, Northwestern Nanotechnology expert. “Microcanoic acids can exploit specific affinity surface binding, allowing them to provide faster turnarounds within 2-3 minutes. Unlike most sensors that rely on a single protein, they can see multiple targets simultaneously.”

The team began by testing the test lines as the frequency used in synthetic biology has developed a deep knowledge base on how tetracyclines work, leading to billions of copies of lead and cadmium, a record of biosensor detection approaches, and cadmium can sense lead and cadmium.

The team hopes to simplify the technology even further. This technology currently requires specialized equipment to visualize the bending movement of microscopes. Ultimately, they believe this device can be generalized for use in human health monitoring of toxins in the body, such as increasing standards for drinking water safety, and for human health monitoring in the context of the environment.