Two are Better than One: Combining ZnO and MgF₂ Nanoparticles Reduces Streptococcus pneumoniae and Staphylococcus aureus Biofilm Formation on Cochlear Implants

Abstract

Streptococcus pneumoniae (S. pneumoniae) and Staphylococcus aureus (S.aureus) are considered the most common colonizers of cochlear implants (CI), which have prompted the search for new ways to inhibit their growth and biofilm development. In the current study, CI‐based platforms are prepared and sonochemically coated with ZnO or MgF2 nanoparticles (NPs), two agents previously shown to possess antibacterial properties. Additionally, a method is developed for coating both ZnO and MgF2 on the same platform to achieve synergistic activity against both pathogens. Each surface is characterized, and the optimal conditions for the NP homogenous distribution on the surface are determined. The ZnO‐MgF2 surface significantly reduces the S. pneumoniae and S. aureus biofilm compared with the surfaces coated with either ZnO or MgF2, even though it contains smaller amounts of each NP type. Importantly, leaching assays show that the NPs remain anchored to the surface for at least 7 d. Finally, biocompatibility studies demonstrate that coating with low concentrations of ZnO‐MgF2 results in no toxicity toward primary human fibroblasts from the auditory canal. Taken together, these findings underscore the potential of using NP combinations such as the one presented here to efficiently inhibit bacterial colonization and growth on medical devices such as CIs.

Highly Effective and Noninvasive Near‐Infrared Eradication of a Staphylococcus aureus Biofilm on Implants by a Photoresponsive Coating within 20 Min

“…Bacteria tend to colonize and adhere to medical devices, especially in medical implants, to form sessile multicellular communities called as biofilms, leading to persistent and chronic device‐related infectious diseases . For example, Staphylococcus aureus ( S. aureus ) accounts for two‐thirds of pathogenic pathogens in orthopedic implant‐related infections, and biofilm formed by S. aureus can proliferate and attach to host tissues to cause local purulent infection or even other systemic inflammatory problems .…”

Sol-Gel Processing of MgF2 Antireflective Coatings

“…The application of an ultrasonic horn for the direct MgF 2 coating of artificial teeth and other substrates is a rather extraordinary technique [ 33 , 34 , 35 ]. Here, also Mg(OAc) 2 × 4H 2 O is used in combination with aqueous HF.…”

NANOCI—Nanotechnology Based Cochlear Implant With Gapless Interface to Auditory Neurons

“…ZnO-MgF 2 and CuZnO were incorporated into the silicone array sonochemically. These nanoparticles proved to be stably locked on the surface with minimal or absent leaching of into artificial perilymph and with substantial inhibition of biofilm formation ( 19 ).…”