3D printed ferroelectric materials eliminate harmful bacteria

Engineers at the University of Bath, working with colleagues at the University of Ulster, have – for the first time – successfully created a new kind of ferroelectric composite material with antimicrobial properties – for use as medical implants – using a novel multi-material 3D printing process.

According to the university, the engineers say the use of electrically responsive ferroelectric materials gives the implants the infection-fighting properties – making them ideal for biomedical applications, such as heart valves, stents, and bone implants that reduce the risk of infection for patients.

While commonplace, all biomedical implants pose some level of risk as materials can carry surface bio-contaminants that can lead to infection.

The team has previously used this 3D printing technique for the fabrication of three-dimensional scaffolds for bone tissue engineering. Dr. Hamideh Khanbareh, a lecturer in materials and structures at The University of Bath’s Department of Mechanical Engineering, is the lead author of the research and says that the development has the scope for wide-ranging applications.

“Biomedical implants that can fight infection or dangerous bacteria such as E. coli could present significant benefits to patients and to healthcare providers,” said Dr. Khanbareh. “Our research indicates that the ferroelectric composite materials we have created have a great potential as antimicrobial materials and surfaces. This is a potentially game-changing development that we would be keen to develop further through collaboration with medical researchers or healthcare providers.”

The innovation is thanks to ferroelectricity, a characteristic of certain polar materials that generate electrical surface charge in response to a change in mechanical energy or temperature. In ferroelectric films and implants, this electrical charge leads to the formation of free radicals known as reactive oxygen species (ROS), which selectively eradicate bacteria. This comes about through the micro-electrolysis of water molecules on a surface of polarised ferroelectric composite material.

The composite material used to harness this phenomenon is made by embedding ferroelectric barium calcium zirconate titanate (BCZT) micro-particles in polycaprolactone (PCL) – a biodegradable polymer widely used in biomedical applications. The mixture of the ferroelectric particles and polymer is then fed into a 3D bioprinter to create a specific porous ‘scaffold’ shape designed to have a high surface area to promote ROS formation.

Testing showed that even when contaminated with high concentrations of aggressive E. coli bacteria, the composite can completely eradicate the bacteria cells without external intervention – killing 70% within just 15 minutes.

The research paper, Additively Manufactured Ferroelectric Particulate Composites for Antimicrobial Applications is published in Advanced Materials Technologies.