1. Application of CAP in Skincare

As an achievement in physics, "cold atmospheric plasma" has broad application prospects in biomedicine.

In January 2014, the International Journal of Antimicrobial Agents (IJAA) published a review stating that cold atmospheric plasma (CAP) is a latest and cutting-edge antibacterial treatment method. It exhibits outstanding efficacy in anti-infection, and is expected to replace traditional treatments such as antibiotics to promote wound healing, holding broad potential in a series of biomedical applications [1].

Cold atmospheric plasma (CAP) possesses unique effects, including high concentrations of charged particles, chemically active particles (RONS), particles in excited and metastable states, activated photons, high electric field intensity, and microcurrent thermal effects. Meanwhile, it can function without damaging the normal cells of skin samples [2][3]. These characteristics determine that CAP has broad application prospects in dermatology, with functions including efficient sterilization, promotion of wound healing, enhancement of growth factors and cell migration, regulation of microcirculation, angiogenesis, and modulation of immune responses [2][3][4][5][6]. On this basis, these functions can be further applied to daily skincare, such as acne removal, freckle lightening, skin rejuvenation, skin condition stabilization, and anti-allergy.

2. Principles of CAP in Skincare

(1) Acne Removal

Over 70% of acne is caused by bacterial infection resulting from hair follicle blockage. CAP achieves the effect of treating acne by eliminating bacteria. Killing the bacteria on the skin in acne-prone areas can effectively reduce redness and swelling caused by bacterial growth. Additionally, the ability of CAP to promote wound healing can accelerate the skin recovery in acne-affected areas and remove acne scars caused by acne. A large number of studies and clinical practices have confirmed [7] that CAP demonstrates excellent efficacy in antibacterial inactivation, anti-infection and anti-inflammation, and promotion of wound healing, making it worthy of promotion and application.

(2) Freckle Lightening

Scars mainly include sore scars, sweat stains, pigment spots, freckles, and knife scars. After skin damage, massive proliferation of dermal tissue leads to scar formation and pigmentation, which are inevitable outcomes of skin tissue injury. After CAP treatment, while the plasma energy acts on the deep dermis, it also stimulates the regeneration of collagen. Fibroblasts release growth factors and cytokines, promoting the formation of elastin and collagen. When high-energy plasma comes into contact with the skin, energy is transmitted to the skin surface, forming a controlled non-vaporizing exfoliation (i.e., a "micro-exfoliation area") with a depth of 100-150 μm in the epidermis and superficial dermis. This can remove dead skin with pigmentation, and at the same time, generate a thermal effect to stimulate the dermal layer of the skin, promoting the proliferation, repair, and rearrangement of collagen fibers and elastic fibers in the dermis. Studies and clinical applications have shown [8][9] that CAP technology has few adverse reactions, can significantly improve the unevenness, texture, and color of mature scars, and is not only effective but also causes minimal damage in the treatment of mature scars.

(3) Skin Rejuvenation

The biological effects of CAP in skin rejuvenation include: ① Generation of active substances; ② Powerful and efficient sterilization ability; ③ Enhancement of stratum corneum penetration (transdermal delivery, plasma perforation), promoting the penetration of active substances (RONS or externally applied essences) into skin cells to boost regeneration and activity (plasma can penetrate the epidermis of skin tissue and reach the dermis 500 μm below the skin surface); ④ Stimulation of cell activity and proliferation of endothelial cells, prompting the skin to produce collagen and promoting the differentiation of new cells, thereby ensuring the timely renewal of skin cells; ⑤ Formation of recoverable microchannels when in contact with the skin, facilitating the absorption of other drugs. Studies have indicated [10] that a moist environment can promote the penetration and retention of RONS in the stratum corneum. When CAP is used in combination with other drugs or essences, a positive feedback process occurs, resulting in better therapeutic effects. The synergistic effects of plasma treatment (sterilization, penetration, electric field, light, and heat) make CAP more effective in treating skin diseases than pulsed electric field therapy, microneedling, and phototherapy.

(4) Skin Condition Stabilization

CAP eliminates external bacteria and viruses, maintaining the stable regeneration of probiotic flora on the skin surface and helping the skin resist external invasion [2][3][11].

(5) Anti-Allergy

When CAP is used alone, it involves purely physical contact, avoiding allergic reactions that may be caused by conventional skincare products [11].

References

[1] Mai-Prochnow, Anne, et al. "Atmospheric pressure plasmas: infection control and bacterial responses." International Journal of Antimicrobial Agents, 2014, 43(6): 508-517.

[2] Liu D, Zhang Y, Xu M, et al. "Cold atmospheric pressure plasmas in dermatology: Sources, reactive agents, and therapeutic effects." Plasma Processes and Polymers, 2020, 17(4). DOI:10.1002/ppap.201900218.

[3] Liu Dawei, Chen Baihan. "Applications of cold atmospheric pressure plasma in dermatology." Journal of Anhui University of Science & Technology, 2022, 5.

[4] Choi Jeong-Hae, Song Yeon-Suk, Lee Hae-June, Hong Jin-Woo, Kim Gyoo-Cheon. "Inhibition of inflammatory reactions in 2,4-Dinitrochlorobenzene induced Nc/Nga atopic dermatitis mice by non-thermal plasma." Scientific Reports, 2016.

[5] Cheng, He; Liu, Xin; Lu, Xinpei; Liu, Dawei. "Active species delivered by dielectric barrier discharge filaments to bacteria biofilms on the surface of apple." Physics of Plasmas, 2016.

[6] Ulrich C, Kluschke F, Patzelt A, Vandersee S, Czaika V A, Richter H, Bob A, Hutten J von, Painsi C, Hüge R, Kramer A, Assadian O, Lademann J, Lange-Asschenfeldt B. "Clinical use of cold atmospheric pressure argon plasma in chronic leg ulcers: A pilot study." Journal of Wound Care, 2015.

[7] Yang Chunjun, Gao Jing, Wang Liyun. "Clinical study on the treatment effect of skin wounds by cold atmospheric plasma equipment." Dermatology Bulletin, 2023, 8.

[8] Wang Shuai. "The effect of micro plasma on collagen remodeling in hypertrophic scar of rabbit ears at different periods." [Master's Thesis], 2017.

[9] Yu Shun, Wang Dan, Yang Jieyan. "Efficacy of Micro-plasma Radiofrequency for Post-traumatic Pigmentation." China Continuing Medical Education, Vol. 10, No.34.

[10] Liu Dingxin, He Tongtong, Zhang Hao. "Penetration Effect of Gas Plasmas on Human Tissues: State-of-the-art and Current Issues." High Voltage Engineering, 2019, Vol.45, No.7: 2329-2342.

[11] Chen Fangyan, Wu Sannü, Song Li, et al. "Research Progress in Plasma Disinfection and Sterilization." Chinese Journal of Disinfection, 2021, 38(02): 144-148.