IIT Madras Patents Chemical-Free Antibacterial Surface That Physically Kills Bacteria And Helps Fight Antimicrobial Resistance

New Delhi: Indian Institute of Technology (IIT), Madras, has patented a chemical-free antibacterial surface that can physically eliminate harmful bacteria without the use of antibiotics, disinfectants, radiation or any other antimicrobial chemicals, officials said.

The innovation aims to address an emerging issue globally, namely Antimicrobial Resistance (AMR) – the ability of disease-causing bacteria to become "superbugs" and resist conventional treatments.

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According to Parasuraman Swaminathan, Professor at the Department of Metallurgical and Materials Engineering, the technology developed does not involve chemical action but specially engineered nanostructures that, upon contact, would kill bacteria by rupturing their cell wall.

"These surfaces are safe for human cells to attach and proliferate on, but bacteria experience severe mechanical stress that ruptures and disintegrates their cell walls. New implant-grade polymer technology fights Antimicrobial Resistance (AMR) by physically destroying bacterial cells and is safe for human cells," he told PTI.

The research findings have been published in the reputed peer-reviewed journal ACS Applied Biomaterials.

"AMR is one of the most pressing healthcare challenges globally. Our work demonstrates a fundamentally different strategy to tackle bacterial contamination. Instead of using chemicals or drugs, we engineered the surface itself to physically destroy bacteria.

"This approach significantly reduces the risk of bacteria developing resistance while offering a long-lasting and environmentally sustainable solution for biomedical and public health applications," Swaminathan said.

The researchers fabricated the antibacterial surfaces using a customised low-pressure plasma process known as Reactive Ion Etching (RIE), which creates dense arrays of nanoscale protrusions on flexible silicone substrates. Unlike conventional antibacterial coatings that rely on chemical agents, the process does not introduce any additional antibacterial materials onto the surface.

One of the most significant findings of the study was the discovery that the plasma process creates a unique stiff surface layer on the silicone substrate, consisting of mixed oxyfluorinated compounds.

"This layer enables efficient transfer of mechanical forces to the bacterial cells, enhancing the bactericidal action of the nanostructures. The researchers report this as a previously unobserved phenomenon on implant-grade silicone surfaces," he said.

The team tested the surfaces against three different bacterial species, including both Gram-positive and Gram-negative bacterias. The nanograss structures demonstrated strong bactericidal activity by rupturing bacterial cell walls and showed significant antibiofilm performance, achieving more than 68 per cent biofilm inhibition across the tested bacterial strains.

Importantly, while the nanostructured surfaces were lethal to bacteria, they remained highly compatible with mammalian cells. Cell viability studies using fibroblast cells showed up to 91 per cent living cells on the engineered surfaces, highlighting their suitability for biomedical applications.

"AMR is nature’s way of showing resistance by bacterial species to active pharmaceutical drugs. The same nature has also taught us to defeat these bacteria, as in the case of nanostructured dragonfly wings. Taking the biomimetic path, we have demonstrated bacteria-killing nanograss structures directly fabricated on implant-grade silicone polymers through a scalable plasma-based process," said Abishek Kumar, Researcher at IIT Madras.

"We also developed computational models that estimate the minimum nanostructure dimensions required for bacterial rupture and carried out detailed thermodynamic analysis to understand how these surfaces resist biofilm formation," Kumar added.

The study also provides new theoretical insights into these mechanobactericidal surfaces. Through finite-element computational modelling, the researchers estimated the minimum nanostructure height required to rupture bacterial cells and validated how nanoscale geometry influences antibacterial performance.

The developed technology can also alter several other industries where microbial contamination is an ongoing problem, beyond healthcare. A few of the potential applications include urinary catheters, medical implants, wound-care products, packaging for pharmaceuticals, hospital equipment, and high-contact surfaces in public places like transport handrails and public infrastructure.

"As the technology is purely mechanical, there is no chemical leaching, toxicity, or the possibility of resistant bacterial strains developing, ensuring the antibacterial activity can effectively delay the sterilisation courses," he said.

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