Enhancing targeted antibiotic therapy via pH responsive solid lipid nanoparticles from an acid cleavable lipid

Area of Science:

• Drug delivery systems
• Nanotechnology
• Infectious diseases

Background:

• Bacterial infections, particularly those caused by Staphylococcus aureus (including MRSA), pose significant challenges.
• Targeted drug delivery to infection sites can improve efficacy and reduce side effects.
• Developing stimuli-responsive systems, such as pH-responsive nanoparticles, is crucial for site-specific drug release.

Purpose of the Study:

• To synthesize an acid-cleavable lipid (SA-3M) for creating pH-responsive solid lipid nanoparticles (SLNs).
• To develop and characterize vancomycin base (VM-FB) loaded SLNs (VM-FB_SA-3M_SLNs) for targeted delivery to acidic infection sites.
• To evaluate the in vitro and in vivo efficacy of these pH-responsive SLNs against Staphylococcus aureus.

Main Methods:

• Synthesis of SA-3M and formulation of VM-FB_SA-3M_SLNs.
• Characterization of SLN size, polydispersity index, zeta potential, and encapsulation efficiency.
• In vitro drug release studies at different pH values (pH 6.5 and pH 7.4).
• In vitro antibacterial assays against methicillin-susceptible and resistant Staphylococcus aureus (MSSA and MRSA).
• In vivo efficacy study in mice skin infection model and histological analysis.

Main Results:

• VM-FB_SA-3M_SLNs exhibited a size of 132.9±9.1nm, PDI of 0.159±0.01, zeta potential of -26±4.4mV, and 57.80±1.1% encapsulation efficiency.
• Drug release was significantly faster at pH 6.5 compared to pH 7.4, indicating pH-responsiveness.
• SLNs demonstrated enhanced antibacterial activity against MSSA and MRSA at pH 6.5.
• In vivo studies showed a 22-fold reduction in MRSA in skin lesions treated with VM-FB_SA-3M_SLNs compared to free VM-FB.
• Histological examination revealed minimal inflammation in the skin treated with the developed SLNs.

Conclusions:

• SA-3M can be utilized to create pH-responsive SLNs for targeted antibiotic delivery.
• These SLNs effectively release vancomycin at acidic infection sites, enhancing antibacterial efficacy.
• The developed pH-responsive SLNs show promise for treating Staphylococcus aureus infections with reduced inflammation.