Biodegradable, Tissue Adhesive Polyester Blends for Safe, Complete Wound Healing.

Pressure-sensitive adhesives typically used for bandages are nonbiodegradable, inhibiting healing, and may cause an allergic reaction. Here, we investigated the effect of biodegradable copolymers with promising thermomechanical properties on wound healing for their eventual use as biodegradable, biocompatible adhesives. Blends of low molecular weight (LMW) and high molecular weight (HMW) poly(lactide-co-caprolactone) (PLCL) are investigated as tissue adhesives in comparison to a clinical control. Wounds treated with PLCL blend adhesives heal completely with similar vascularization, scarring, and inflammation indicators, yet require fewer dressing changes due to integration of the PLCL adhesive into the wound. A blend of LMW and HMW PLCL produces an adhesive material with significantly higher adhesive strength than either neat polymer. Wound adhesion is comparable to a polyurethane bandage, utilizing conventional nonbiodegradable adhesives designed for extremely strong adhesion.

Pressure-Sensitive Tissue Adhesion and Biodegradation of Viscoelastic Polymer Blends.

Viscoelastic blends of biodegradable polyesters with low and high molecular weight distributions have remarkably strong adhesion (significantly greater than 1 N/cm2) to soft, wet tissue. Those that transition from viscous flow to elastic, solidlike behavior at approximately 1 Hz demonstrate pressure-sensitivity yet also have sufficient elasticity for durable bonding to soft, wet tissue. The pressure-sensitive tissue adhesive (PSTA) blends produce increasingly stronger pull-apart adhesion in response to compressive pressure application, from 10 to 300 s. By incorporating a stiffer high molecular weight component, the PSTA exhibits dramatically improved burst pressure (greater than 100 kPa) when used as a tissue sealant. The PSTA's biodegradation mechanism can be switched from erosion (occurring primarily over the first 10 days) to bulk chemical degradation (and minimal erosion) depending on the chemistry of the high molecular weight component. Interestingly, fibrosis toward the PSTA is reduced when fast-occurring erosion is the dominant biodegradation mechanism.

Improving the adhesion, flexibility, and hemostatic efficacy of a sprayable polymer blend surgical sealant by incorporating silica particles.

Commercially available surgical sealants for internal use either lack sufficient adhesion or produce cytotoxicity. This work describes a surgical sealant based on a polymer blend of poly(lactic-co-glycolic acid) (PLGA) and poly(ethylene glycol) (PEG) that increases wet tissue adherence by incorporation of nano-to-microscale silica particles, without significantly affecting cell viability, biodegradation rate, or local inflammation. In functional studies, PLGA/PEG/silica composite sealants produce intestinal burst pressures that are comparable to cyanoacrylate glue (160 mmHg), ∼2 times greater than the non-composite sealant (59 mmHg), and ∼3 times greater than fibrin glue (49 mmHg). The addition of silica to PLGA/PEG is compatible with a sprayable in situ deposition method called solution blow spinning and decreases coagulation time in vitro and in vivo. These improvements are biocompatible and cause minimal additional inflammation, demonstrating the potential of a simple composite design to increase adhesion to wet tissue through physical, noncovalent mechanisms and enable use in procedures requiring simultaneous occlusion and hemostasis. STATEMENT OF SIGNIFICANCE: Incorporating silica particles increases the tissue adhesion of a polymer blend surgical sealant. The particles enable interfacial physical bonding with tissue and enhance the flexibility of the bulk of the sealant, without significantly affecting cytotoxicity, inflammation, or biodegradation. These studies also demonstrate how silica particles decrease blood coagulation time. This surgical sealant improves upon conventional devices because it can be easily deposited with accuracy directly onto the surgical site as a solid polymer fiber mat. The deposition method, solution blow spinning, allows for high loading in the composite fibers, which are sprayed from a polymer blend solution containing suspended silica particles. These findings could easily be translated to other implantable or wearable devices due to the versatility of silica particles.