Enzyme from IISc lab helps break down toxic effluents

A team of Indian Institute of Science (IISc) scientists has developed an enzyme mimetic capable of degrading toxic chemicals in industrial wastewater in the presence of sunlight.

Developed at IISc’s Materials Research Centre (MRC), these laboratory-manufactured nano-sized enzyme mimetics, or nanozymes, can address limitations in the mass production of enzymes.

Subinoy Rana, assistant professor at MRC and corresponding author of the paper, said the practical use of enzymes — proteins that catalyse most of the biological reactions in living systems — is limited by factors, including sensitivity to breakdown/damage, complex production and recycling procedures, and high costs.

IISc noted that laccase, a natural enzyme used for degrading phenols in industries, is extracted from a fungus called white rot, but production of the enzyme depends on the fungus’ availability. There is also the problem of storage; most of the natural enzymes require storage at cooler temperatures, often as low as -20°C.

Nanozymes can mimic such natural enzymes and overcome these practical challenges. In the study, published in the journal Nanoscale, the team synthesised NanoPtA, a platinum-containing nanozyme that can be converted into powder form for industrial use.

NanoPtA mimics the function of oxidases (natural enzymes that remove hydrogen from substrates in the presence of oxygen to give water). It can degrade pollutants in wastewater by oxidising them in sunlight, thereby reducing the toxicity of the wastewater.

Tests on common effluents that pollute water validated the nanozyme’s ability to degrade even small (micromolar) quantities of phenols and dyes within 10 minutes, when placed in sunlight. The researchers found that the NanoPtA complex was quite stable, lasting for up to 75 days at room temperature.

Applications in healthcare

The nanozyme also comes with potential healthcare applications. The team tested its ability to oxidise neurotransmitters like dopamine and adrenaline — when oxidised, these molecules show a change in colour in the solution, which can be used to measure their concentration. “This is important because these neurotransmitters are associated with Parkinson’s and Alzheimer’s diseases, and cardiac arrest,” Rohit Kapila, first author and PhD student at MRC, said.

What are enzyme mimetics?  

Enzyme mimetics are small compounds that possess catalytic activity that mimics the activity of larger enzyme-based molecules.

A schematic representation of toxic chemical degradation in water under sunlight using NanoPtA.