Photorheology of bioadhesive dendrimer polycaprolactone composites

Toxicity, low adhesion strength, and complexity of application are the major challenges that prevent utilization of synthetic surgical adhesives. To address this challenge, a platform of fully synthetic UVA curing bioadhesive is evaluated on the binary composites consisting of polyamidoamine (PAMAM) grafted with aryl-diazirine (PAMAM-g-diazirine, PDz) and multi-arm polycaprolactone triols (PCLT). PCLT is chosen as a bioresorbable polymer matrix that serves as a plasticizer for the viscous PDz. Upon low dose UVA light, grafted diazirine converts to reactive carbenes that crosslink by covalent insertion. Rheological investigation created G″ vs. G′ vector maps of the liquid-to-solid transition, allowing comparison of PDz/PCLT ratio, PCLT molar mass, and type of plasticizer. The vector maps reveal crosslinking kinetics are dependent on the PCLT concentration within the composite, while the molar mass of liquid PCLT does not affect the crosslinking kinetics. Liquid PDz/PCLT composite adheres to dry substrates as well as hydrated soft tissue mimics. Infrared spectroscopy provides an insight into the crosslinking mechanism where UVA-generated carbenes covalently insert into proximate polymer chains mainly on –O–H sites. Carbene-induced intermolecular locking transforms the material from liquid to elastomeric composite polymer matrix in less than 10 J per sq. cm of UVA exposure.