Akhilesh Gaharwar, Associate Professor at Texas A&M, and graduate student Patrick Lee are developing a new class of hydrogels that can use light for drug delivery and regenerative medicine treatments.

Hydrogels are widely used in the body to aid tissue regeneration and drug delivery. However, once in, it can be difficult to control for optimal use. A team of researchers from the Department of Biomedical Engineering at Texas A&M University is developing a new way to manipulate the gel – with light.

PhD student Patrick Lee and Dr. Akhilesh Gaharwar, associate professor, are developing a new class of hydrogels that can use light in a variety of ways. Light is a particularly attractive source of energy because it is limited to a predefined area and can be fine-tuned by the time or intensity of the exposure. Her work was recently published in the journal Advanced materials.

Photosensitive hydrogels are an emerging class of materials used to design non-invasive, non-contact, precise, and controllable medical devices in a variety of biomedical applications, including photothermal therapy, photodynamic therapy, drug delivery, and regenerative medicine.

Lee said photosensitive biomaterials are widely used in biomedical applications; however, current light sources, such as ultraviolet light and visible light, cannot penetrate the tissue sufficiently to interact with the hydrogel. Instead, the team is researching near-infrared light (NIR), which has a higher penetration depth.

The team uses a new class of two-dimensional nanomaterials known as molybdenum disulfide (MoS2), which have shown negligible toxicity to cells and superior NIR absorption. These nanosheets with high photothermal conversion efficiency can absorb NIR light and convert it into heat, which can be developed to control thermoresponsive materials.

In the group’s previous study, published in Advanced Materials, certain polymers react with MoS2 nanosheets to form hydrogels. Building on this discovery, the team also uses MoS2 nanosheets and thermoresponsive polymers to control the hydrogel under NIR light through a photothermal effect.

“This work uses light to activate the dynamic interactions between polymer and nanomaterials,” said Gaharwar. “In NIR exposure, MoS2 acts as a crosslinking epicenter by connecting to several polymer chains via defect-driven click chemistry, which is unique.”

NIR light enables therapeutic hydrogels to form internally in the body for precise drug delivery. With cancer therapy, most drugs can remain in the tumor, which reduces the side effects of chemotherapy. In addition, NIR light can generate heat in the tumors to remove cancer cells, known as photothermal therapy. Therefore, a synergistic combination of photothermal therapy and chemotherapy has shown greater effectiveness in destroying cancer cells.

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This study is funded by the New Innovator Award from the National Institutes of Health and the Texas A&M President’s Excellence Fund through X? Grant and T3.

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