Photodynamic Therapy: A New Precision Skin Rejuvenation Option in the Beauty Industry

What is LED Phototherapy? 

LED phototherapy is a cutting-edge, non-invasive optical skincare technology that uses light of different wavelengths to penetrate deep into the skin, activating cell vitality and promoting skin self-repair. Unlike lasers or intense pulsed light (IPL), LED phototherapy is gentle and safe, requires no recovery period, and is suitable for all skin types. It has been widely used in anti-aging, acne treatment, skin barrier repair, and post-operative care. With higher light energy output, more precise wavelength control, and five-color light wave synergy technology, this device can penetrate deeply into different layers of the skin, comprehensively enhancing cell repair capabilities. It not only significantly enhances anti-aging, anti-inflammatory, and post-operative repair effects but also maximizes the skin's self-repair potential, elevating phototherapy skincare to a new level.

What is the principle of LED phototherapy? 

The mechanism of visible light in skin phototherapy mainly involves the molecular, cellular, and tissue levels. The light energy emitted by the phototherapy device is absorbed by chromophores in skin cells and converted into heat and chemical energy. It promotes the synthesis of intracellular ATP, increases the concentration of intracellular reactive oxygen species, thereby enabling cells to better perform metabolic activities, improve skin energy and immunity, and promote collagen formation.

Benefits of Different Colored LED Light Therapy

1. LED Red Light 660nm:

Red light therapy can promote metabolism, accelerate blood circulation, improve skin hydration, increase skin collagen, enhance skin elasticity, and smooth fine lines.

Clinical Applications: Anti-aging, whitening, skin rejuvenation, making skin hydrated, radiant, and soft; repairing and removing wrinkles; repairing wounds, treating sensitive skin; promoting hair growth, improving follicular alopecia; improving anemia, asthma, and cardiopulmonary function; relieving fatigue, improving sleep, and relaxing the mind.

2. LED Blue Light 415nm:

Blue LED light therapy has the effects of sterilization, skin purification, cell activation, and promoting protein and collagen synthesis.

Clinical Applications: Acne, acne scars.

3. Green LED (530nm):

Green LED phototherapy is commonly used to even out skin tone, inhibit pigmentation, and relieve sensitivity. Green light can slowly constrict dilated capillaries, has a mild anti-inflammatory effect, and promotes the production of serotonin (a hormone with calming and euphoric effects), which can relax and soothe the mind and body, slowly lower blood pressure, and relieve certain neuropathic pain, such as migraines.

4. Yellow LED (590nm):

Yellow LED phototherapy can improve cellular oxygen exchange, stimulate microcirculation, break down pigments, promote lymphatic drainage, and improve rough skin, erythema, and poor blood circulation.

Clinical applications: telangiectasia, sensory dullness, dull and loose skin, yellowish skin tone, cold hands and feet, loss of appetite.

5. Near-infrared LED (850nm):

Near-infrared LED phototherapy can effectively combat inflammation, relieve pain, stimulate collagen proliferation and ATP production, thereby promoting the growth of epithelial cells after trauma, promoting the healing of burns and scalds, and promoting the repair of eczema and dermatitis.

LED Phototherapy Applications in Beauty

1. Anti-aging Skin

The light source used for treatment has a wavelength range of 630-850 nm, with the main wavelength being 630-660 nm. The light source dose varies depending on the irradiated area, and both pulsed and continuous light modes are used. Studies have shown that LED phototherapy can promote skin microcirculation, affect the production of platelet-derived growth factor (PDGF) and transforming growth factor-β (TGF-β), and inhibit cell apoptosis.

2. Anti-inflammatory

The light source used to reduce inflammatory responses has a wavelength of 560-660 nm, with a dose range of 0.1-17 J/cm². Both continuous and pulsed modes are available. Studies have shown that LED phototherapy exerts its anti-inflammatory effect by inhibiting the synthesis of PEG-2.

3. Acne Treatment

The pathogenesis of common acne is not fully understood, but it mainly involves four factors: excessive keratinization of the hair follicle, increased sebum secretion influenced by androgen secretion, colonization by Propionibacterium acnes, and inflammation. Phototherapy is considered an alternative to drug treatment for common acne. Acne is often treated with a combination of red and blue light. The mechanism involves *Propionibacterium acnes* synthesizing and storing endogenous porphyrins, primarily coprophyrin I and protoporphyrin IX, with absorption peaks around 415 nm. Therefore, when these porphyrins are exposed to visible light (especially blue light), they are photoexcited to generate reactive free radicals and singlet oxygen, damaging the cell membrane of *Propionibacterium acnes* and leading to bacterial death. Conversely, red light affects sebum secretion from sebaceous glands, alters the behavior of keratinocytes, and regulates cytokines in macrophages and other cells.

4. Wound Healing

Similar to improving skin aging, light irradiation can accelerate wound healing by promoting cell proliferation, collagen production, and increasing local blood circulation, with fibroblasts playing a crucial role. The light source parameters used for wound healing are similar to those used for improving skin aging, with continuous phototherapy being the primary method. Studies have shown that LED phototherapy can significantly improve wound healing speed.

5. Scar Removal

Hypertrophic scars and keloids are benign skin tumors, usually forming after surgery, trauma, or acne, and are difficult to eradicate. Fibroblast proliferation and excessive collagen deposition are their two main characteristics. The light source used for scar treatment is primarily near-infrared light with wavelengths greater than 800 nm, and the irradiation method is mainly continuous light. Studies have shown that LED phototherapy can significantly reduce postoperative scar formation.

6. Photoprotection

Red/infrared light combats photodamage by promoting collagen secretion from fibroblasts, reducing the production of matrix metalloproteinases (MMPs), and stimulating keratinocytes to release nerve growth factor (NGF) and promote its gene expression. NGF can protect melanocytes from UV damage and induce apoptosis by upregulating intracellular BCL-2 levels. The wavelengths used for photoprotection are mainly red and infrared light in the 630-660 nm range, and the irradiation method is mainly continuous light. Studies have shown that LED phototherapy can significantly reduce erythema after UV exposure.

7. Inhibition of Melanin Production

The light sources used to inhibit melanin production are mainly 590nm yellow light and 660nm red light, with a dose of 20 J/cm², primarily using continuous light. Studies have shown that LED phototherapy can inhibit melanocyte-stimulating hormone-induced tyrosinase activity and reduce the expression of MITF and tyrosinase in B16F10 cells.

Medical Applications of LED Phototherapy

1. Dermatological Treatment: Medical-grade LED phototherapy devices can be used to treat skin conditions such as herpes, eczema, dermatitis, melasma, and allergic skin diseases.

2. Wound Repair: It is suitable for wounds that are difficult to heal, such as traumatic injuries, orthopedic wounds, surgical wounds, burns, various ulcers, bedsores, diabetic wounds, fistulas, and other chronic wounds. Red LED light can help wounds heal.

3. Rehabilitation Therapy: LED phototherapy can be used to treat various injuries, sprains, sports injuries, and various types of pain.