A state-of-the-art guide to the sterilization of thermoplastic polymers and resin materials used in the additive manufacturing of medical devices

Abstract

Continuous development of additive manufacturing technologies has reached new areas, including medical research and healthcare applications, where precision, highly accurate reproducibility, disinfection, or even sterility of the end product is essential. The study aims to critically evaluate the effect of different sterilization and disinfection methods for most commonly used additive manufacturing technologies and materials in medical device development: PLA (polylactic acid), PETG (polyethylene terephthalate glycol), ABS (acrylonitrile butadiene styrene), and HIPS (high impact polystyrene) for material extrusion technology (FFF; fused filament fabrication), polyamide (PA2200) for powder bed fusion technology (SLS; selective laser sintering), MED610™ for PolyJet™ material jetting, and standard Formlabs™ white resin (V4) for SLA (stereolithography) technology. The materials were tested before and after different sterilization and disinfection protocols, including treatment with 70% ethanol, chlorine solution, H2O2 plasma sterilization, autoclave and dry heat sterilization, applying 10 and 20 cycles in all cases. Bacteriostatic/fungistatic and sterility tests were performed using Escherichia coli, Enterococcus faecalis, and Candida albicans as reference strains. Cytotoxicity was evaluated using A549 cells. The samples showed significant structural or aesthetic alterations detected by various mechanical tests, scanning electron microscopy, or differential scanning calorimetry (DSC-TGA). No significant cytotoxic effect was revealed during the experiment. Our results can serve as a guide for the selection of effective sterilization and disinfection methods for the most common materials used in 3D printing in medical and healthcare applications.