Silk Moths Enable New Biopolymer Sensor To Detect Environmental Toxins

Researchers at Tufts University’s Silklab have created a new biopolymer sensor that detects bacteria, toxins, and dangerous chemicals in the environment. It can be printed like ink on almost any material, or embedded into films, sponges, and filters, or molded like plastic. The research team foresees a number of applications for the biopolymer sensors, such as personal and patient monitoring and infection control in health-care settings and environmental sensing in the home, workplace, for the military, and in disaster settings.

The sensor is based on computationally designed proteins and silk fibroin extracted from the cocoons of the silk moth Bombyx Mori. An enzyme – similar to that found in fireflies – causes the sensor to glow when it detects pre-determined threats, such as airborne and waterborne toxins, infections, and even cancer. The sensors are sprayed with a non-toxic chemical after being potentially exposed to the threats. If the target is present, the sensor generates light – with the intensity of emitted light providing a quantitative measure of the concentration of the target.

The research team was able to demonstrate how the sensor emits light within minutes as it detects the SARS-CoV-2 virus that causes COVID, anti-hepatitis B virus antibodies, the food-borne toxin botulinum neurotoxin B, or human epidermal growth factor receptor 2 (HER2), an indicator of the presence of breast cancer. The team have already created a proof-of-concept silicone bra pad that when worn can absorb secreted fluid, report the levels of HER2 hormone, and provide an indication whether breast cancer may be present.

“The combination of lab-designed proteins and silk is a sensor platform that can be adapted to detect a wide range of chemical and biological agents with a high degree of specificity and sensitivity,” says Fiorenzo Omenetto, director of the Silklab at Tufts. “For example, SARS-CoV-2 and anti-hepatitis B antibodies can be measured at levels that approach clinical assays.”

As the sensing element is modular, the developers can swap in newly designed proteins to capture specific pathogens or molecules to measure, while the light emitting mechanism remains the same. 

“Using the sensor, we can pick up trace levels of airborne SARS-CoV-2, or we can imagine modifying it to adapt to whatever the next public health threat might be,” Omenetto said.