Melittin from Bee Venom Encapsulating Electrospun Fibers as a Potential Antimicrobial Wound Dressing Patches for Skin Infections

Abstract

Skin infection compromises the body's natural defenses. Several antibiotics are no longer effective owing to the evolution of antimicrobial-resistant (AMR) bacteria, hence, the constant development of novel antibacterial agents. Naturally occurring antibacterial agents may be potential candidates for AMR bacterial infection treatments; however, caution should be taken when administering such agents due to the high incidence of toxicity. A fibrous material system from a biocompatible polymer that could be used as a skin patch for skin infections treatment caused by AMR bacteria is proposed in this study. Bee venom's active ingredient, melittin, was fabricated using electrospinning technology. Scanning electron microscopy showed that melittin-loaded fibers had smooth surfaces with no signs of beads or pores. The average diameter of this fibrous system was measured to be 1030 ± 160 nm, indicating its successful preparation. The melittin fibers' drug loading and entrapment efficiency (EE%) were 49 ± 3 µg/mg and 84 ± 5%, respectively. This high EE% can be another successful preparatory criterion. An in vitro release study demonstrated that 40% of melittin was released after 5 min and achieved complete release after 120 min owing to the hydrophilic nature of the PVP polymer. A concentration of ≤10 µg/mL was shown to be safe for use on human dermal fibroblasts HFF-1 after 24-h exposure, while an antibacterial MIC study found that 5 μg/mL was the effective antimicrobial concentration for S. aureus, A. baumannii, E. coli and Candida albicans yeast. A melittin-loaded fibrous system demonstrated an antibacterial zone of inhibition equivalent to the control (melittin discs), suggesting its potential use as a wound dressing patch for skin infections.

Keywords: antimicrobial resistant bacteria; antimicrobial wound dressing; bee venom; electrospinning; electrospun fibers; melittin; skin infection.

Figure 1

Melittin’s chemical structure which was drawn by ACD/ChemSketch.

Figure 2

SEM images of blank (a) and melittin-loaded (b) fibers showed that both fibrous systems had smooth surfaces with no signs of bead or pores, with average diameters of 990 ± 130 nm, 1030 ± 160 nm, respectively.

Figure 3

FTIR transmissions of PVP, melittin, PM and melittin fibers showing the characteristic peaks merge at 1500 cm⁻¹ and 1620 cm⁻¹ in the fibrous system but not in the PM (green arrows), which indicates the intermolecular formation bonds between melittin and PVP. A distinctive peak of melittin at 948 cm⁻¹ which appeared in the PM and drug-loaded fibers and not in the PVP transmission suggests melittin presence in the fibrous system (red arrows). PM: physical mixture, DL: drug-loaded.

Figure 4

Melittin-loaded fibers release in PBS (pH 5.5), showing an initial burst release of 40% after 5 min and a complete drug release after 180 min. The results are presented as average ± SD of independent triplicates.

Figure 5

Cell viability of melittin at different concentrations exposed to HFF1 cells for 24, 48 and 72 h. The results show that melittin with a concentration of ≤10 µg/mL is considered safe after 24-h cell exposure but not after 48 or 72 h. The data of this MTS assay represented cell viability %, and the results are presented as average ± SD of independent triplicates.

Figure 6

The zone of inhibition of melittin-loaded fibers against different antimicrobial-sensitive and -resistant bacterial strains, in addition to C. albicans yeast, compared to melittin containing discs (positive control). It shows that both melittin-loaded fibers and discs were effective against all strains when applied at equivalent amounts, suggesting that melittin retained its antimicrobial activity after electrospinning. The results are presented as average ± SD of independent triplicates.