3D-printed surface coated with natural photosensitizer for photodynamic inactivation of methicillin-resistant Staphylococcus aureus using visible light.

The use of polylactic acid (PLA) coated with photosensitizer (PS) and activated by visible light could represent a novel, inexpensive, and eco-friendly self-sterilizing material to produce customized biomedical devices with antimicrobial properties. The rise of antibiotic resistance highlights the urgent need for alternative antimicrobial strategies, like Methicillin-resistant Staphylococcus aureus (MRSA), which represents a major global health concern, responsible for severe invasive diseases to minor skin infections and asymptomatic nasal colonization. Antimicrobial photodynamic inactivation (aPDI) has emerged as a promising technique, using the synergistic effects of light, oxygen, and a photosensitizer to generate reactive oxygen species (ROS) that eradicate bacteria. Brazil's rich biodiversity offers a reservoir of natural compounds, such as Eugenia uniflora (EU) extract, which has demonstrated effective antimicrobial activity when used in aPDI. This study explored the development of a 3D-printed self-sterilizing surface by combining aPDI and EU extract to combat MRSA. Polylactic acid (PLA) discs were impregnated with EU extract and evaluated for their ability to reduce MRSA colonies under visible light, assessing bacterial growth at 0, 8, and 24 h. Results showed significant reductions in MRSA colonies under visible light after 8 h (~ 50%), which were enhanced at 24 h (~ 70%). ROS involvement was confirmed, with EDTA and azide restoring ~ 50% of bacterial growth, implicating metal ions and singlet oxygen in the mechanism. DNA damage assays revealed heightened genotoxic effects under light exposure, as shown by DNA smearing. This innovative approach underscores the potential of EU coated 3D-printed surfaces in reducing nosocomial infections. Further studies will examine ROS generation and antibiofilm capabilities.