Light Irradiated Coating Increases Non-Surgical Obesity Treatment | Research & Technology | April 2022

WASHINGTON, DC, April 19, 2022 – A multi-institutional research team in South Korea has enhanced the existing functionality of appetite suppressant implants in the stomach with photodynamic therapy, coating such an implant with a light-activated dye which kills the cells that produce ghrelin, known as the “hunger hormone”. Researchers have used and donned intragastric satiety-inducing devices, or ISDs, in labor. Researchers in the ongoing work designed and introduced these implants in 2019.

Appetite suppressant implants, which can act like miniature balloons in the stomach, are non-surgical alternatives for treating obesity. These implants can be inserted into the stomach through the mouth. ISDs consist of a stent that fits in the lower esophagus and is attached to a disc that sits in the stomach opening. The disc contains a hole in its center that allows food to pass through.

Although tests in pigs have shown that ISDs reduce food intake and weight gain by improving feelings of fullness and reducing levels of ghrelin, which is produced by cells near the top of the stomach , the device led to complications, including acid reflux.

Current work aimed to further suppress ghrelin by first coating an ISD with a compound that could kill some of the ghrelin-producing cells upon light interaction. The researchers’ design in the work was to remove the implant afterwards to avoid the side effects associated with the initial design of their device.

An implant (blue and grey) creates a feeling of satiety by pressing on the stomach and, when activated by a laser (black), kills the cells that produce ghrelin, known as the “hunger hormone”. The research advances 2019 work that led to the development of a device to treat obesity non-surgically, but resulted in side effects, including acid reflux. Courtesy of Applied materials and ACS interfaces.

The researchers coated the ISDs with methylene blue, which is an FDA-approved photosensitizer and drug. They then placed them in the stomachs of young pigs. When they exposed the coated ISDs to laser light, the coating released singlet oxygen which killed nearby ghrelin-producing cells and then quickly disappeared.

After one week, the treatment halved ghrelin cells and body weight gain compared to an untreated pig, although the researchers said these differences diminished in the following weeks unless the light treatment was given. say again. Still, with further development, they believe the procedure could become a minimally invasive treatment to help obese patients lose weight.

The authors of the article were supported by the Korea Medical Device Development Fund grant funded by the Korean government.

The research has been published in Applied materials and ACS interfaces (

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