1. Definition and Characteristics of Cold Atmospheric Plasma (CAP)

（1）Definition

Cold Atmospheric Plasma (CAP) is a partially ionized non-equilibrium plasma that operates at or near room temperature and atmospheric pressure. Unlike traditional plasmas (which require high temperatures and low pressures), its room-temperature operation makes it highly suitable for medical and skincare applications. It is composed of charged particles (electrons, ions), reactive oxygen and nitrogen species (RONS), ultraviolet radiation, and electromagnetic fields, forming a "fourth state of matter" distinct from solid, liquid, and gas.

（2） Core Characteristics

• Non-thermal property: Treatment temperature stays at 37–38°C, preventing tissue thermal damage.
• Broad-spectrum activity: Has antibacterial, wound-healing, anti-inflammatory, and anti-tumor functions.
• Mechanism of action: Induces oxidative stress through RONS (e.g., OH⁻, H₂O₂, NO) to destroy microbial structures and regulate cell signaling pathways.

2. Core Applications of CAP in Dermatology

3. Mechanism of Action of CAP

（1） Core Role of RONS

• Short-lived species (OH⁻, O₂⁻) directly damage microbial nucleic acids and proteins.
• Long-lived species (H₂O₂, NO₂⁻) regulate cellular signaling pathways (e.g., NRF2 pathway).

（2）Physical Effects

• Electric field effect: Penetrates the stratum corneum (plasmaporation) to enhance drug transdermal absorption (e.g., niacinamide permeability increases by 60-fold).
• Lipid regulation: Changes skin lipid structure and optimizes barrier function.

4. Safety and Clinical Challenges

（1）Safety Evidence

• In vitro experiments show no genotoxicity to normal cells.
• In clinical studies, only 1% of patients have mild erythema, with no serious adverse reactions.

（2）Main Challenges

• Lack of standardization: CAP device parameters (e.g., power, treatment time) differ significantly across studies, with no unified treatment protocol.
• Unclear mechanism: The precise molecular mechanism of RONS-cell interaction has not been fully clarified.
• Cost and accessibility: High cost of professional devices restricts its use in primary medical institutions.

5. Future Research Directions

（1）Develop portable CAP devices to facilitate home care applications.

（2）Explore combination therapies of CAP with biomaterials (e.g., plasma-activated hydrogel).

（3）Carry out large-scale clinical trials to verify long-term safety and efficacy stability.

References

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