Uropathogenic Escherichia coli express hairlike proteinaceous surface projections, known as chaperone–usher pathway (CUP) pili. Type 1 pili are CUP pili with well-established pathogenic properties. The FimH adhesin subunit of type 1 pili plays a key role in the pathogenesis of urinary tract infections (UTIs) as it mediates the adhesion of the bacteria to urothelial cells of the bladder. In this study, two breast cancer cell lines, MDA-MB-231 and MCF-7, were used to demonstrate the cytotoxic activities of type 1 piliated uropathogenic E. coli UTI89 on breast cancer cells in a type 1 pili and FimH-mediated manner. E. coli were grown in static and shaking conditions to induce or inhibit optimal type 1 pili biogenesis, respectively. Deletion constructs of UTI89 ΔfimH and a complemented strain (UTI89 ΔfimH/pfimH) were further utilized to genetically assess the effect of type 1 pili and FimH on cancer cell viability. After incubation with the different strains, cytotoxicity was measured using trypan blue exclusion assays. UTI89 grown statically caused significant cytotoxicity in both breast cancer cell lines whereas cytotoxicity was reduced when the cells were incubated with bacteria grown under shaking conditions. The incubation of both MDA-MB-231 and MCF-7 with UTI89 Δfim operon or ΔfimH showed a significant reduction in cytotoxicity exerted by the bacterial strains, revealing that type 1 pili expression was necessary for cytotoxicity. Complementing the ΔfimH strain with pfimH reversed the phenotype, leading to a significant increase in cytotoxicity. Incubating type 1 pili expressing bacteria with the competitive FimH inhibitor D-mannose before cancer cell treatment also led to a significant reduction in cytotoxicity on both MDA-MB-231 and MCF-7 cancer cells, compared to vehicle control or D-mannose alone, indicating the requirement for functional FimH for cytotoxicity. Overall, our results reveal that, as opposed to UTI89 lacking type 1 pili, type 1 piliated UTI89 causes significant cancer cell mortality in a FimH-mediated manner, that is decreased with D-mannose.

Background: Nanoparticles have been used in nanomedicine for therapeutic purposes. Lipids have been a popular choice of material in the synthesis of biocompatible nanoparticles due to their ability to encapsulate diverse therapeutic agents. However, once introduced into biological environments, nanoparticles rapidly adsorb proteins on their surface, forming a protein corona that can alter drug release, targeting and cellular interactions. Understanding these effects is essential for optimizing solid lipid nanoparticles (SLNs) as drug delivery systems. Methods: SLNs were synthesized using stearic acid (SA) as the lipid core and stabilized with surfactants, Tween 80 and SDS (sodium dodecyl sulphate). To mimic in vitro conditions, SLNs were incubated with 5% FBS (foetal bovine serum) for varying durations to allow soft and hard protein corona formation. SLNs were characterized for size and surface charge via dynamic light scattering while UV visible spectroscopy, protein adsorption studies, FTIR and the Bradford Assay were employed to confirm and quantify protein corona formation. In parallel, molecular docking was conducted to analyse protein-nanoparticle interactions. To investigate the potential influence of protein corona formation on drug release, ceftriaxone (CTX) was encapsulated within SLNs followed by immediate incubation to allow corona formation. Subsequent evaluations included drug leakage, release profile and antibacterial efficacy against Staphylococcus aureus and Pseudomonas aeruginosa . Results: Protein adsorption was confirmed on all SLN formulations and closely correlated with nanoparticle surface charge. Formulations with more negative zeta potentials adsorbed higher amounts of protein. SDS concentration influenced protein adsorption with higher SDS content reducing overall corona formation. Molecular docking revealed that protein-ligand interactions were maintained by hydrogen bonding and hydrophobic forces. Drug release studies confirmed that the protein corona reduced cumulative drug release by 6%. Antibacterial assays confirmed slightly reduced efficacy against both strains aligning with the reduced cumulative drug release. Conclusions: This study demonstrated that protein corona formation on dual-surfactant SLNs is strongly influenced by surface charge and surfactant composition and in turn modulates drug release dynamics. The protein corona was shown to modulate drug release with potential implications for antibacterial efficacy. These findings highlight the importance of tailoring surface properties to control protein-nanoparticle interactions thus providing insight into the design of lipid-based nanoparticles for therapeutic applications.

To synthesize cytarabine loaded SLNs modified with the RGD peptide as a ligand, suitable for effective cancer therapy.SLNs were synthesized by the high shear, hot homogenization technique. A 2 leve...