Antimicrobial Peptide Screening for Designing Custom Bactericidal Hydrogels.

Area of Science:

• Biomaterials Science
• Infectious Diseases
• Immunology

Background:

• Staphylococcus aureus (S. aureus) is a major cause of infections.
• Antimicrobial peptides (AMPs) are key components of the innate immune system with broad-spectrum antimicrobial activity.
• AMP-functionalized hydrogels show potential for preventing bacterial infections, but optimal dosing and synergistic effects require further investigation.

Purpose of the Study:

• To synthesize and characterize three AMPs with distinct antibacterial properties.
• To determine the minimum inhibitory concentrations (MICs) of individual AMPs against methicillin-susceptible S. aureus (MSSA) and methicillin-resistant S. aureus (MRSA).
• To evaluate the efficacy of AMP-immobilized hydrogels in preventing MRSA adhesion and biofilm formation, and to identify synergistic AMP combinations for enhanced antibacterial activity.

Main Methods:

• Synthesis of three antimicrobial peptides (AMPs): DD13-RIP, indolicidin, and P10.
• Determination of MICs for each AMP against MSSA and MRSA.
• Immobilization of AMPs onto hydrogels at their respective MICs and assessment of MRSA adhesion and biofilm inhibition.
• Checkerboard assays to identify synergistic AMP combinations against MRSA using fractional inhibitory concentration indices (FICIs).
• Fabrication of hydrogels with synergistic AMP combinations at half their MICs and evaluation of MRSA killing efficacy and mammalian cell viability.

Main Results:

• Hydrogels with immobilized AMPs at their MICs prevented MRSA adhesion and biofilm formation.
• Synergy was identified between indolicidin and P10 against MRSA (FICI ≤ 0.5).
• Hydrogels containing synergistic AMP combinations at half their MICs (7.8 µM total peptide) demonstrated high efficacy in killing MRSA.
• Mammalian cells cultured on these hydrogels exhibited high viability, indicating biocompatibility.

Conclusions:

• AMP-functionalized hydrogels are effective against S. aureus, including MRSA.
• Synergistic combinations of AMPs offer enhanced antibacterial potency.
• These AMP-hydrogels are biocompatible and selectively target bacteria, presenting a promising alternative to conventional antibiotics for treating S. aureus infections.