Interview: The new antibacterial coating that could save lives – and healthcare system budgets

A new antibacterial technology is aiming to innovate orthopaedic implants and surgery with its 99.999 per cent kill rate of bacteria most commonly found in operating rooms.

Periprosthetic joint infection – a serious infection in replaced joints – is a significant health problem with a high mortality rate and high healthcare costs. Patients who acquire an infection in orthopaedic implants can end up with serious joint damage and require a second joint replacement.

Precision orthopaedics company Onkos Surgical is aiming to address this issue with the development of its novel technology that protects implants from bacterial infections. The technology – called NanoCept – is a novel antibacterial coating that is applied to orthopaedic implants.

The coating has been shown to achieve a 99.999 per cent bacteria kill rate in American Society for Testing and Materials (ASTM) studies.

Speaking to Health Tech World, Patrick Treacy, founder and CEO of Onkos Surgical, explains that the five-year mortality rate for patients with joint infections is higher than for many common cancers, including breast, prostate, and, in some studies, colon cancer.

“This is a devastating condition not only for patients but also for healthcare systems, with costs projected to reach nearly US$2bn by 2030. Treating a single infection can cost upwards of US$80,000,” explains Treacy.

“While standard approaches like improving sterile procedures and operating room protocols help reduce infections, a technology to directly protect the implant itself had never been approved by the FDA. That’s where our company saw an opportunity.

“We discovered a groundbreaking technology from Princeton University, which met our stringent criteria.

“It had to be a device, not a drug, to align with our expertise, and ideally, it would follow a Class II pathway for regulatory approval – avoiding the risks of Class III trials, where success is only determined at the end.

“Crucially, the technology also had to avoid using antibiotics to prevent concerns about resistance and superbugs while ensuring a high safety profile and broad-spectrum efficacy against bacteria common in operating theatres.”

NanoCept’s journey began in May 2018, when Onkos first presented the technology to the FDA.

Initially, NanoCept was classified as a drug, which led to a 14-month process of providing data, engaging in discussions, and educating regulators. Eventually, Treacy explains that the FDA agreed it was a device.

However, with no predicate device for comparison, it became a de novo application – a premarket submission that classifies novel medical devices based on risk – which Treacy says added complexity.

Despite the pandemic and other delays extended the approval process for NanoCept to six years – the technology has now become the first-ever FDA-approved antibacterial technology for orthopaedic implants.

NanoCept works by forming a covalent bond – a chemical bond where two atoms share a pair of electrons – with implant surfaces, creating a 70nm thin layer that kills bacteria via quaternary ammonia molecules.

“To put this into perspective, a typical human hair is about 100,000 nanometres in diameter – so we’re talking about something incredibly thin and small,” said Treacy.

“Here’s how it works: a covalent bond is the strongest type of chemical bond – it shares an electron, making it incredibly stable. We apply a linker molecule that attaches to the oxide layer on the surface of the metal implant, forming a covalent bond. This essentially makes the coating part of the implant itself, rather than a layer that could flake off.

“Next, we attach a quaternary ammonium molecule to the linker. This molecule, often abbreviated as MDPB, has been widely used for decades in products like mouthwash and toothpaste as a preservative. After attaching the molecule, we polymerise it, essentially creating a polymer chain. At the end of this chain is a positively charged nitrogen ion.

“This positive charge acts like a tiny spike. When bacteria land on the surface of the implant, the positive charge punctures the bacterial cell wall, causing the bacteria to “bleed out” their internal contents (cytoplasm) and die.”

Treacy says to imagine the entire surface of the implant covered with tiny spikes, each about 70 nanometres tall, with positive charges on their tips. These spikes destroy bacteria on contact, regardless of whether the bacteria are gram-positive or gram-negative.

“Despite all of the precautions taken with surgeons, with double gloving and scrubbing hands and laminar flow and draping patients and wearing space suits – despite all of that, contamination in the operating room still exists,” said Treacy.

“We are so enthusiastic about the promise of this technology because it’s estimated that 60 to 70 per cent of joint infections are from contamination in the operating theatre.”

Onkos says that the NanoCept technology has now been successfully used in multiple surgical procedures.

“We’ve demonstrated efficacy in several ways and the fact that it is a device, and we were able to get it through the FDA,” said Treacy.

“This is a big step forward. There’s still a lot more research that then needs to go on, but it’s another tool in the armamentarium. We’re also hopeful that perhaps in some way, maybe we’ve broken a bit of a glass ceiling with the FDA that would allow other technologies to get to market to help patients as well.”

Onkos recently secured a US$35m investment from Horizon Technology Finance to help with the manufacturing and commercialisation of NanoCept, and now plans to build a scaled manufacturing facility and continue research and development work.

Treacy explains that the first approval was focused on the company’s ELEOS Limb Salvage System, which is a hip and knee replacement system for missing bone, and that Onkos is now actively working with FDA to proliferate the technology across the rest of its portfolio.