(128b) Biomaterials for Photothermal Tissue Sealing and Repair

Repair of damaged tissues, including skin, often requires surgical closure. In most cases, surgical closure is facilitated by primary intention with devices including sutures and staples. However, lack of immediate tissue approximation, high potential for scarring, including in visible areas of the body, susceptibility to infection, and long procedure times necessitate new approaches for tissue repair especially for unmet needs where current approaches are suboptimal in performance. Light-activated tissue sealing is an emerging strategy that facilitates rapid, liquid-tight approximation of ruptured tissues, but the lack of effective biomaterials compromises efficacy. I will discuss our advances in the generation, characterization, evaluation, and delivery of laser-activated sealants (LASEs) and nanofibers in which, molecular or nanoparticle chromophores are embedded within natural polypeptide or polysaccharide matrices and fibers. Irradiation of LASEs and nanofibers with near infrared light elicited a photothermal response, which, in turn, engendered robust sealing and accelerated repair of soft tissues including skin, intestines, and peripheral nerves, both ex-vivo and in live animals. I will also discuss a new approach in which biomaterials alone can be used for simultaneous photothermal conversion of non-ionizing light as well as concomitant tissue sealing, thus dispensing the need of nanoparticles or dyes as photothermal convertors. Incorporation of antibiotics or bioactive materials further enhanced the efficacy of LASEs. In addition to acute trauma, slow-healing and chronic wounds, including in diabetic and obese patients, are a significant cause for morbidity. Advanced treatments, including biologicals, have shown some promise but have largely not succeeded in cases of intractable wound pathologies. I will describe our new findings on the delivery of immunomodulating bioactive molecules and polypeptide biomaterials (e.g. silk) in combination with growth factor nanoparticles with an eye towards developing a temporal delivery strategy for specifically modulating individual stages of tissue repair, leading to accelerated healing, including in diabetic and obese mice. Taken together, our studies demonstrate that biomaterials, in concert with delivery of light and bioactive molecules, show strong translational promise for accelerating wound healing, and efficacious tissue sealing and repair.