# Using silica nanoparticles to deliver antibiotics for treating Gram-positive bacterial infections in a 3D-bioprinted dermal model

## TL;DR

This study explores using silica nanoparticles to deliver antibiotics for treating skin infections in a 3D-printed skin model.

## Contribution

The work introduces antibiotic-loaded silica nanoparticles for targeted treatment of Gram-positive bacterial infections in a 3D-bioprinted dermal model.

## Key findings

- Antibiotic-loaded SiNPs significantly reduced bacterial colony-forming units compared to untreated and SiNP-only treatments.
- The 3D-bioprinted dermal model effectively mimicked skin for testing bacterial infection treatments.
- Clindamycin and tetracycline showed enhanced efficacy when delivered via silica nanoparticles.

## Abstract

Bacterial antibiotic resistance has emerged as a significant global threat, making it increasingly challenging to effectively treat infections in patients. Nanomedicine technologies can be implemented for the targeted delivery of medications and drugs to patients. This work investigates the use of silica nanoparticles (SiNPs) loaded with the clindamycin and tetracycline antibiotics to treat Staphylococcus epidermidis infection in a 3D-bioprinted dermal model. SiNPs are stable, biocompatible, and can be loaded with small molecules like antibiotics.

The SiNPs were synthesized and loaded with antibiotics. The loading efficiency of the SiNPs was determined by UV-Vis spectroscopy and high-performance liquid chromatography. Dome-shaped constructs containing fibroblasts were 3D printed using a fibrin-based bioink to mimic the dermis of skin. These constructs were then inoculated with bacterial cultures labeled with green fluorescent protein (GFP) 4 days post printing and then treated with antibiotic-loaded SiNPs to determine their effect on bacterial growth. After the incubation phase, the bacteria were cultured in broth to determine the colony-forming unit (CFU) count on toxin superantigen (TSA) plates containing 10 mg/mL chloramphenicol.

The CFU count of the 3D-bioprinted human constructs samples treated with antibiotics was significantly lower than both the SiNP-treated and untreated samples. The results suggest that antibioticreleasing SiNPs can serve as a more efficient treatment for skin bacterial infections.