Killing Bacteria by Faradaic Processes through Nano- Hydroxyapatite/MoOx Platforms

SIEBEN, JUAN M.; PLACENTE, DAMIÁN; BALDINI, MÓNICA; RUSO, JUAN M.; LAIUPPA, JUAN A.; SANTILLÁN, GRACIELA E; MESSINA, PAULA V.

ACS APPLIED MATERIALS & INTERFACES

AMER CHEMICAL SOC

Lugar: Washington; Año: 2023 vol. 15 p. 25884 - 25897

1944-8244

Following the secular idea of "restitutio ad integrum", regeneration is the pursued option to restore bone lost after a disease; accordingly, complementing antibiotic and regeneration capacity to bone grafts represents a great scientific success. This study is a framework proposal for understanding the antimicrobial effect of biocompatible nano-hydroxyapatite/MoOx (nano-HA/MoOx) platforms on basis of their electroactive behaviour. Through cyclic voltammetry and chronoamperometry measurements, the electron transference capacity of nano-HA and nano-HA/MoOx electrodes was determined in the presence of pathogenic organisms: Pseudomona aeruginosa and Staphylococcus aureus. Faradaic processes were confirmed and related to the switch of MoO42- / PO43- groups in the original hexagonal nano-HA crystal lattice and to the extent of OH-vacancies that act as electron acceptors. Microscopic analysis of bacteria’s ultrastructure showed a disruptive effect on the cytoplasmic membrane upon direct contact with the materials that is not evident in the presence of eukaryotic cells. Experiments support the existence of a type of extracellular electron transfer (EET) process that alters the function of bacteria cytoplasmic membrane accelerating their death. Our findings provide strong quantitative support for a drug-independent biocidal physical approach based on EET processes between microorganisms and phosphate ceramics that can be used to combat local orthopaedic infections associated with implants.