Developing an antimicrobial & radiopaque material suitable for 3D printing

The use of 3D printing in medicine has increased in recent years. It can be used to manufacture one-off, patient-specific devices where commercial solutions are unavailable or unsuitable for the patient. Many 3D printing technologies used in medicine are polymer-based. While polymers have many properties making them suitable for healthcare, they can promote bacterial growth in the form of biofilms. Gram-positive Staphylococci bacteria are the primary cause of biofilm formation, which can colonise indwelling medical devices resulting in patients contracting hospital-acquired infections. Infection can lengthen a patient’s stay, especially if a device needs to be replaced, as well as complicating the patient’s recovery and care. In the case of vulnerable patients, hospital-acquired infections can cause serious harm or even result in death.

A range of metals and metal oxides are identified for testing to select the most suitable filler for antimicrobial 3D printing. Essential characteristics of the filler are good dispersion stability within the resin, maintaining UV curing properties of the resin, inhibiting Gram-positive bacteria when 3D printed and maintaining mechanical properties of the base resin when 3D printed. Staphylococcus epidermidis and Staphylococcus aureus were selected as the Gram-positive bacteria for this research.

Silver oxide showed strong antimicrobial effects towards S. epidermidis and S. aureus. Silver oxide performed well in dispersion stability tests and maintained UV curing properties of the resin so was deemed suitable for 3D printing. When 3D printed using vat polymerisation, silver oxide showed strong antimicrobial effects in well?known concentrations as low as 1 wt.%. Mechanical properties were maintained at this concentration. The most suitable technology for 3D printing the antimicrobial resin developed during this research was Digital Light Processing which is a type of Vat Polymerisation.