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Updated: Oct 12, 2025
Evaluation of Antimicrobial Activities of Nanoparticles and Nanostructured Surfaces In Vitro
Published on: April 21, 2023
Potentiality of Melittin-Loaded Niosomal Vesicles Against Vancomycin-Intermediate Staphylococcus aureus and
Sirikwan Sangboonruang1, Natthawat Semakul2, Mohammad A Obeid3
1Biotechnology Section, Graduate School, Chiang Mai University, Chiang Mai, Thailand.
Background:
Staphylococcus aureus is an important human pathogen, especially causing skin and soft tissue infections (SSTIs). Over the decades, the infections caused by antibiotic-resistant strains have often become life-threatening. Consequently, exploration and development of competent approaches to combat these serious circumstances are urgently required.
Methods:
The antibacterial activity of melittin (Mel) on S. aureus, methicillin-resistant S. aureus (MRSA) and clinical isolates of vancomycin-intermediate S. aureus (VISA) was investigated by minimum inhibitory concentration (MIC) and time-killing assays. The localization of Mel on the bacterial cell was visualized by confocal laser scanning microscopy and its effect on the membrane was indicated based on propidium iodide uptake. The non-ionic surfactant vesicle (NISV) or niosome nanocarrier was established for Mel loading (Mel-loaded NISV) by the thin-film hydration method. Physicochemical and in vitro biological properties of Mel-loaded NISVs were characterized. The cellular uptake of Mel-loaded NISVs was evaluated by holotomography analysis. In addition, an ex vivo study was conducted on a porcine ear skin model to assess the permeation ability of Mel-loaded NISVs and their potential to inhibit bacterial skin infection.
Results:
The effective inhibitory activity of Mel on skin pathogens was demonstrated. Among the tested strains, VISA was most susceptible to Mel. Regarding to its function, Mel targeted the bacterial cell envelope and disrupted cell membrane integrity. Mel-loaded NISVs were successfully fabricated with a nano-size of 120-200 nm and entrapment efficiency of greater than 90%. Moreover, Mel-loaded NISVs were taken up and accumulated in the intracellular space. Meanwhile, Mel was released and distributed throughout the cytosol and nucleus. Mel-loaded NISVs efficiently inhibited the growth of bacteria, particularly MRSA and VISA. Importantly, they not only penetrated epidermal and dermal skin layers, but also reduced the bacterial growth in infected skin.
Conclusion:
Mel-loaded NISVs have a great potential to exhibit antibacterial activity. Therapeutic application of Mel-loaded NISVs could be further developed as an alternative platform for the treatment of skin infection via dermal and transdermal delivery.
Insights
Melittin-loaded niosome nanocarriers show potent antibacterial activity against antibiotic-resistant skin pathogens like MRSA and VISA. This novel formulation effectively penetrates skin, offering a promising alternative for treating skin infections.
Area of Science:
- Antimicrobial drug development
- Nanotechnology in medicine
- Dermatology
Background:
- *Staphylococcus aureus* is a major cause of skin and soft tissue infections (SSTIs).
- Antibiotic-resistant strains, such as MRSA and VISA, pose significant treatment challenges.
- Novel therapeutic strategies are urgently needed to combat resistant bacterial infections.
Purpose of the Study:
- To investigate the antibacterial activity of melittin (Mel) against *S. aureus*, MRSA, and VISA.
- To develop and characterize melittin-loaded non-ionic surfactant vesicles (Mel-loaded NISVs) as a nanocarrier system.
- To evaluate the efficacy of Mel-loaded NISVs in an ex vivo skin infection model.
Main Methods:
- Antibacterial activity assessed using MIC and time-killing assays.
- Mel localization and membrane disruption visualized via microscopy and propidium iodide uptake.
- Mel-loaded NISVs fabricated using thin-film hydration; characterized for size, entrapment efficiency, and in vitro properties.
- Ex vivo porcine ear skin model used to assess skin permeation and antibacterial efficacy.
Main Results:
- Mel demonstrated effective inhibition of skin pathogens, with VISA being most susceptible.
- Mel-loaded NISVs were successfully fabricated (120-200 nm, >90% entrapment efficiency) and showed intracellular uptake.
- Mel-loaded NISVs significantly inhibited MRSA and VISA growth and reduced bacterial load in infected skin.
- The nanocarriers penetrated epidermal and dermal skin layers.
Conclusions:
- Mel-loaded NISVs exhibit significant potential as an antibacterial agent.
- This nanocarrier system offers a promising alternative for treating skin infections.
- Mel-loaded NISVs are suitable for dermal and transdermal delivery applications.
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