Scientists at the Materials Research Centre (MRC) of the Indian Institute of Science, Bengaluru, have achieved a ground-breaking development in the field of wastewater treatment. They have unveiled a novel enzyme mimetic that effectively degrades toxic chemicals in industrial wastewater when exposed to sunlight. This breakthrough overcomes the inherent limitations of natural enzymes and presents a significant step forward in environmental protection and potential healthcare applications.

Toxic chemicals, when released into the environment, can have detrimental effects on ecosystems, water bodies and human health. Efficient degradation helps prevent or minimise these negative impacts. It involves several key principles and techniques:

Catalysis: Catalysts are substances that speed up chemical reactions without being consumed themselves. In wastewater treatment, catalysts are often used to facilitate the degradation of toxic chemicals.

Specificity: Efficient degradation processes are often highly specific to the particular chemicals being targeted. For example, certain enzymes or catalysts are designed to break down specific types of pollutants. This specificity ensures that only the harmful substances are targeted while leaving non-harmful compounds intact.

Speed: Efficiency in degradation also involves timely removal of toxic chemicals. Some catalysts, like nanozymes, can work rapidly, breaking down pollutants within a short time-frame.

Stability: The catalysts or enzymes used for degradation must be stable under the conditions in which they are applied. For example, they should remain active over a range of pH and temperature conditions. The stability of the catalyst or enzyme is crucial to ensure its long-term effectiveness.

Environmental impact: An efficient degradation process should have minimal negative environmental impacts. It should not produce harmful by-products or waste materials that can further contaminate the environment.

Cost-effectiveness: Efficient degradation methods should be cost-effective, making them practical for industrial and environmental applications. This cost-effectiveness can involve factors such as the ease of production and the availability of materials.

In response to these challenges, the team at MRC has developed a platinum-containing nanozyme called NanoPtA. This synthetic nanozyme mimics the function of natural oxidases and exhibits exceptional stability in a wide range of pH and temperature conditions. They act as catalysts to accelerate the breakdown of pollutants in the presence of sunlight.

Mass-producing natural enzymes, such as laccase, has been an expensive and time-consuming process, further exacerbated by their temperature-sensitive storage requirements.

Synthetic vs Natural

Natural enzymes are often extracted from living organisms, which can be a time-consuming and costly process. The availability of natural enzymes depends on factors like the growth of the source organism. In contrast, synthetic nanozymes can be manufactured in a laboratory, allowing for greater control over production, consistency and scalability. This makes them more accessible for industrial applications and research.

Many natural enzymes are sensitive to changes in temperature and pH, requiring special storage conditions and careful handling. Synthetic nanozymes can be designed to be more stable and robust, and can remain stable at room temperatures for extended periods, eliminating the need for specialised storage conditions.

Natural enzymes often face challenges in terms of recycling and reuse. In contrast, synthetic nanozymes can be designed with features that make them more amenable to recycling, reducing overall waste and cost.

Some natural enzyme extraction processes can have environmental implications, such as habitat disruption and resource consumption. Synthetic nanozymes can be produced with reduced environmental impact, especially if sustainable and eco-friendly materials are used.

How does it work?

When NanoPtA comes into contact with wastewater, it forms unique tape-like structures that emit light. This enables oxidation of pollutants present in wastewater when exposed to sunlight, thereby reducing the toxicity of the water.

The team’s research has demonstrated that NanoPtA can effectively degrade common water pollutants — including phenols and dyes, even in micromolar quantities — within just ten minutes of exposure to sunlight. Remarkably, the NanoPtA complex remains stable at room temperature for up to 75 days, making it a groundbreaking development in the field of enzyme mimetics.

Beyond its potential to address wastewater pollution, the nanozyme also holds promise in healthcare applications. The team has successfully tested NanoPtA’s ability to oxidize neurotransmitters like dopamine and adrenaline, which are associated with neurological and neurodegenerative diseases such as Parkinsons and Alzheimer’s. The change in colour resulting from the oxidation of these molecules could offer a valuable diagnostic tool.

Looking ahead, the researchers are investigating more cost-effective metal alternatives to platinum for its synthesis, with the goal of scaling up production for industrial use.