Gold Photothermal Therapy – Targeting Acne at its Root Cause


Acne is such a common condition that any one of us would have experienced it at some point in time. The condition is chronic and recurring, which makes it difficult to treat. Often we still have to rely on diligent usage of creams, and sometimes oral medication.

Many people are not willing to consume or a medication because of the side-effects. For example, while it is very effective, oral isotretinoin (Roaccutane) causes dryness, sun sensitivity, and even more serious side-effects such as increased blood cholesterol and hair loss.

For this reason, many of my patients seek in-clinic treatments for their acne. However, acne treatments are not always effective. Lasers, although commonly used, sometimes work and sometimes don’t. In addition, many treatments are often required, resulting in a very expensive treatment regime.

As a result, I am always on the lookout for better and more effective acne treatments. We started offering Gold Photothermal Therapy (PTT) for acne a few months ago. This treatment was FDA approved in 2018, but only reached Singapore not long ago.

To understand how this treatment works, we first need to understand the role of sebaceous glands in contributing to acne.

The Role of Sebaceous Glands in our Skin

Sebaceous glands are small oil-producing glands present in the skin of mammals like ourselves. They cover the entire body surface body except the palms, soles and dorsum of the feet. They are largest and most concentrated in the face and scalp.

A sebaceous gland is is usually attached hair follicles in a pilo-sebaceous unit, consisting of an enlarged infundibulum, a multilobular sebaceous gland with multiple ducts converging into an opening onto the skin (1). These openings are the pores on our skin.

Sebaceous glands have an important role. They produce and secrete sebum – the waxy yellow substance which we squeeze out of a blackhead or whitehead. Sebum is a complex substance made up of complex oils including triglycerides and fatty acid breakdown products, wax esters, squalene, cholesterol esters and cholesterol. It protects our skin and ensures it is healthy by lubricating it, reducing friction and by forming a waterproof barrier.

Overactive Sebaceous Glands Cause Acne Vulgaris

Overactive sebaceous glands are one of the main culprits for acne. For acne to occur, there is first excessive production of sebum, coupled with blockage of the hair follicle caused by skin cells which are are not shed quickly enough (2). Clogging occurs – which result in comedones, or whiteheads and blackheads. When the clogged pores get colonised by bacteria, and later get inflamed, pimples occur.

The Gold PTT treatment targets the first step in the pathogenesis of acne – the hyperactive sebaceous gland.

Overactive sebaceous glands are the root cause of acne

Gold PTT – How it Works

In Gold PTT treatment, we are combining the principles of PTT with gold micro particles. The treatment uses specially designed gold microparticles with a 120 nm diameter silica core and 15 nm thick gold shell.

Using lasers to treat acne is not new. Lasers work on acne by heating up the skin. Using different wavelengths and pulse widths, we can try our best to target the pilosebaceous unit. This principle is known as selective photothermolysis.

Photothermal therapy (PTT) takes this principle one step further. It is a type of light therapy which uses electromagnetic radiation, commonly in the near-infrared wavelengths in the form of lasers, for the treatment of various medical conditions including cancer. This concept of using substances to enhance the efficacy of lasers is also not new. It was previously used in another acne treatment called photodynamic therapy (PDT).  However, there are some differences. Unlike PDT, PTT causes less redness and downtime, because longer wavelength lasers, which is less energetic, is used (3). In the past, PDT was notorious for causing post treatment sun sensitivity. The important differences that last time is needed for PTT. The time taken for the gold to penetrate hair follicles is only about 15 minutes compared to 1 to 2 hours for PDT.

When applied to the skin, the gold nano shells penetrate deeply into the follicles. When a laser is applied, the gold nanoshells localized in the follicles absorb light and exhibit plasmon resonance, a phenomenon in which conduction electrons are excited in resonance with the incoming electromagnetic field, to create very strong optical absorption (4). The gold particles get heated, and induce what is known as focal thermolysis of the sebaceous glands. Basically they destroy part of the hyperactive glands.

Gold nanoparticles structure
Diagram showing how Gold nanoparticles and the laser works together

Gold PTT – Long-lasting Acne Reduction

Changes to the sebaceous glands can already be seen immediately post-treamtent. Histology showed local heat injury to the infundibulum in 84% and to sebaceous gland in 47% of cases. The maximum depth of the thermal injury was 1.43 mm, with an average depth of 0.47 mm. The adjacent dermis and the epidermis did not show damage(4). This is important Because it means that the surrounding skin is minimally affected and there will be very little downtime or complications. This is shown in the picture below:

A collage of
sebaceous follicles, showing typically observed patterns of
thermal damage to the infundibulum, sebaceous duct, and
glands. Paithankar DY, Sakamoto FH, Farinelli WA, et al. Acne Treatment Based on Selective Photothermolysis of Sebaceous Follicles with Topically Delivered Light-Absorbing Gold Microparticles. J Invest Dermatol. 2015;135(7):1727-1734. doi:10.1038/jid.2015.89

With sebum production reduced, we have a long-lasting cleansing effect in the sebaceous follicles. Researchers found there there was a reduction of 53% of inflammatory acne lesions, 4 months after 3 treatment sessions in one study, and a reduction of 61% of inflammatory acne lesions, 7months after 3 treatments in another (4).

One other beneficial effect we see from the treatment, is reduction of pore size!

Gold PTT – Long-lasting Acne Reduction

The treatment process is relatively simple and surprisingly comfortable. Cleansing of the skin is first done  to remove comedones and clogs for the gold solution to penetrate better. The gold solution is applied, and penetration is enhanced with ultrasound wave irradiation. Next, a laser is applied to heat up the skin gently. Finally, post care creams are applied to ensure proper healing of the skin.

Cleansing of the skin
Penetration of gold nanoparticles via ultrasound
Activation of PTT with laser

Acne Requires a Holistic Approach

Laser treatments are not the only way to treat acne. You still need creams, oral medication, and facials in a holistic management plant. Lifestyle also plays a role – recently with increased mask wearing, I see so many more patients with worsening acne. Oh these patients, treating their acne includes staying at home all so that they can minimise mask wearing!

Treating acne requires a comprehensive conversation with your doctor and it is often a long journey ahead.

References :

  1. Kligman AM. An overview of acne. J Invest Dermatol. 1974;62(3):268-287. doi:10.1111/1523-1747.ep12676801
  2. Makrantonaki E, Ganceviciene R, Zouboulis C. An update on the role of the sebaceous gland in the pathogenesis of acne. Dermato-endocrinology. 2011 Jan;3(1):41-49. DOI: 10.4161/derm.3.1.13900.
  3. Park KY, Han HS, Hong JY, Seo SJ, Lee SJ. Gold nanoshell-mediated photothermal therapy for acne vulgaris. Dermatologic Therapy. 2019;e13189
  4. Paithankar DY, Sakamoto FH, Farinelli WA, et al. Acne Treatment Based on Selective Photothermolysis of Sebaceous Follicles with Topically Delivered Light-Absorbing Gold Microparticles. J Invest Dermatol. 2015;135(7):1727-1734. doi:10.1038/jid.2015.89