New Acne Treatment: Gold Photothermal Therapy (Gold PTT)

What is Gold PTT and how does it work?

Gold PTT, short for Gold Photothermal Therapy, is a type of treatment used to alleviate Acne Vulgaris (or simply “acne”). As the name suggests, the treatment uses specialised gold nanoparticles to convert photon energy from a laser to thermal energy, which is then used in the acne treatment.

The human skin

Before we discuss in depth how gold PTT works to cure acne, we need to understand what causes acne and to do that, we need to first take a look at the human skin.

The skin is made up of 3 main, distinct layers. The outermost layer is the epidermis, a keratinised waterproof layer whose main function is protection from the environment. This layer is what isolates pathogens outside our body and prevents infections.

Beneath the epidermis lies the dermis (sometimes referred to as “corium”), where most of the metabolic processes associated with the skin takes place. In the dermis we can find vascular and lymphatic vessels, nerves endings, hair follicles, sebaceous and sweat glands. The dermis is also where skin structural proteins like collagen and elastin are found.

Beneath the dermis is the hypodermis (also known as “subcutaneous tissue”), the deepest layer of our skin. It is attached to the dermis by collagen and elastin fibres and is where subcutaneous fat (fat under the skin) is stored. The roots of hair follicles usually extend to this layer too.

Acne Vulgaris

Pathophysiology

Acne is a disease of the pilosebaceous unit. It arises when pores on the skin, which are the openings to hair follicles become clogged with dead skin cells, oil from sebaceous glands or even bacteria. They are usually caused by a combination of four abnormal physiological processes:

1. Increase oily sebum production
2. Excess keratin deposition
3. Infection of the follicle by the bacteria Cutibacterium acnes
4. Inflammatory response by the skin

The formation of acne first begins with accumulation of dead skin cells in the follicle. In regular, healthy skin, the hair follicles naturally exit the follicle. However, excessive secretion from sebaceous glands can cause the dead skin tissue to clump together and become hard to eject from the follicle. Eventually the pore becomes clogged by debris and minor inflammation and swelling occurs, forming a microcomedone. If the microcomedone forms near the surface of the skin and is exposed to air, the melanin within the dead skin cells become oxidised to a dark colour, forming an open comedo (blackhead). Otherwise in anoxic conditions, a closed comedo (whitehead) is formed. The presence of C. acnes colonies in the pores only worsens this process. The bacteria thrives in the oily and anoxic environment within the clogged pores, which can cause severe inflammation if left unchecked. Pus, sebum and bacterial colonies can build up in the follicle, leading to pustules or papules. If the follicles ruptures from this build-up or from external stress, nodules and cysts can form.

The mechanisms behind Gold PTT

Now that we understand the processes behind acne formation, we can now understand how Gold PTT treats acne at the root by tackling these issues.

We shall begin with a description of a type Gold PTT treatment process.

After the patient has cleansed the treatment area, an ampoule containing gold nanoparticles is applied to the skin. These nanoparticles are designed to have increased affinity for the hair follicles and sebaceous glands, and are hence more readily absorbed by them as compared to the epidermis. The nanoparticles are then delivered into the hair follicles in the face using Bellasonic, one of the latest machines imported from South Korea, which utilises both Local Dynamic Micro-Ultrasound (LDM) and sonophoresis (a drug delivery method using ultrasound). The combination of the 2 allows for a non-invasive and painless ,yet effective delivery of the nanoparticles accurately into the hair follicles, leaving surrounding skin undisturbed. The excess superficial nanoparticles are then wiped off the skin surface.

After the delivery, a specialised long-pulse diode laser is used to excite the gold nanoparticles. Unlike other types of laser treatment, the laser used in Gold PTT does not interact with the skin tissue directly but achieves its effects indirectly via the gold nanoparticles. The laser has a wavelength of 800nm or 1064nm in the infrared range, tuned to match the absorbance wavelength of the gold nanoparticles. This allows the laser to effectively excite gold atoms in the nanoparticles, heating them up without damaging the surrounding tissue. The leftover gold nanoparticles used in the treatment are inert, and will not react with your skin in any way after the treatment. They will shed away naturally with dead skin cells.

The localised heat from the nanoparticles effectively tackle 2 of the 4 physiological processes leading to acne. Firstly, it thermally lyses the overactive sebaceous glands permanently, reducing their secretion of oily sebum. Secondly, the heat also kills C. acnes bacteria in the follicles. The reduced secretion makes it less likely for the follicles to become clogged, and the reduction in bacterial activity greatly decreases the chances of inflammation. By tackling these 2 processes, Gold PTT effectively neutralises ongoing outbreaks, and prevent future ones.

One of the biggest advantages of Gold PTT treatment is the localisation. The treatment targets only the acne prone areas on the face, leaving the existing healthy areas unaffected, allowing us to tailor every session to the individual’s needs.

Effectiveness of Gold PTT

In several clinical trials, almost all the participating patients have significantly less inflammatory skin lesions after receiving Gold PTT treatment. In one such study, patients, including severe cases with large numbers of papules and pustules on the face, saw an average of 50% improvement in symptoms after up to 8 sessions of Gold PTT treatment over 16 weeks. Most, if not all of the cases suffered no or only mild side effects. This included slight redness, swelling and soreness, all of which subsided in a few hours or days.

Is Gold PTT treatment painful?

A mild tingling sensation will be felt during the sonophoresis with Bellasonic as well as when the laser interacts with the gold nanoparticles. The skin might feel slightly warm too. There is otherwise minimal pain and discomfort from Gold PTT.

How soon can I see results?

Mild results can be seen after the first session. Results are expected to improve with subsequent sessions, and may be required for more persistent cases