Assessing the Antibacterial Potential and Biofilm Inhibition Capability of Atorvastatin-Loaded Nanostructured Lipid Carriers via Crystal Violet Assay

<b>Background/Objectives</b>: Atorvastatin (ATR), an antihyperlipidemic drug with a potential antibacterial effect, was investigated in this study. Like other statins, ATR has been repurposed for several uses, ranging from anti-inflammatory to antimicrobial applications, and has demonstrated successful results. However, the efficacy of ATR is limited by its low solubility, indicating an opportunity for its encapsulation in a nanotechnology-based drug delivery system. <b>Methods</b>: Nanostructured lipid carrier (NLC) formulations were prepared using high-pressure homogenization and ultrasonication. The formulations were characterized, including their particle size, polydispersity index, zeta potential, encapsulation efficiency, and in vitro release. Antibacterial activity against methicillin-resistant <i>Staphylococcus aureus</i> (MRSA), <i>Escherichia coli</i> (<i>E. coli</i>), and <i>Staphylococcus aureus</i> (<i>S. aureus</i>) was evaluated using the growth curve (bacterial growth over time) and well diffusion methods (zone of inhibition and minimum inhibitory concentration (MIC) determination). The crystal violet assay was employed to assess biofilm inhibition. <b>Results</b>: The NLC formulations were optimized, and the size and zeta potential of the blank nanoparticles were 130 ± 8.39 nm and -35 ± 0.5 mV, respectively. In comparison, the encapsulated NLCs had a size of 142 ± 52.20 nm and a zeta potential of -31 ± 1.41 mV. The average encapsulation efficiency was 94%, and 70% of the drug was released after 24 h. The ATR-loaded NLCs showed significantly enhanced antibacterial activity by reducing the minimum inhibitory concentration by 2.5-fold for <i>E. coli</i>, 1.8-fold for <i>S. aureus</i>, and 1.4-fold for MRSA, and promoting more effective bacterial growth inhibition. Notably, biofilm inhibition was significantly improved with ATR-NLCs, achieving 80% inhibition for <i>S. aureus</i>, 40% for <i>E. coli</i>, and 30% for MRSA, compared to free ATR (<i>p</i> < 0.001). These findings suggest that NLC encapsulation enhances ATR's antimicrobial efficacy and biofilm suppression. <b>Conclusions</b>: This study identified NLCs as successful carriers of ATR, significantly enhancing its antibacterial efficacy and biofilm inhibition capabilities. This formulation, which shows antimicrobial potential against both Gram-positive and Gram-negative bacteria, should be further studied and developed against different resistant microbial strains.