Open globe injuries are full-thickness injuries sustained to the eye wall (cornea or sclera), which cause immediate drops in intraocular pressure that may lead to retinal detachment and permanent vision loss if not treated rapidly after injury. The current standard of care for open globe injuries consists of suturing the margins closed, but the technique can be time-consuming, requires specialized training and equipment, and can lead to patient discomfort, abrasion, and infection from eye rubbing. We engineered an injectable, thermoresponsive sealant (TRS) and a custom tool to occlude open globe injuries. The smart hydrogel sealant consists of physically cross-linked -isopropylacrylamide copolymerized with butylacrylate. At low temperatures, it can be injected as a liquid, and when raised to body temperature, a heat-induced gelation converts the hydrogel into a solidified occlusion. The sealant can be repositioned or removed without causing additional trauma via exposure to cold water. In vitro and ex vivo assessments of mechanical adhesion to eye tissue revealed maintenance of intraocular pressure that is five times greater than the physiological range with reversible seal strength comparable to cyanoacrylate (super glue). In vivo assessment in a rabbit model of ocular trauma demonstrated ease of use for TRS deployment, statistically significant improvement in wound sealing, and no evidence of neurotoxicity, retinal tissue degradation, or significant chronic inflammatory response after 30 days of exposure. Given the advantages of body heat-induced gelation, rapid reversible occlusion, and in vivo safety and efficacy, shape-adaptable TRSs have translational potential as smart wound sealants for temporary occlusion of surgical incisions or traumatic injuries.

SUMMARY The RAG complex in vertebrate V(D)J recombination must coordinate its catalytic steps with its binding to its two distant recombination sites in a manner that is still unclear. Here we test the ability of the plausible reaction schemes to fit observed time courses for RAG nicking and DNA hairpin formation inV(D)J recombination. The reaction schemes with the best fitting capability (a) strongly favor a RAG tetrameric complex ([RAG12:RAG22]) over a RAG octameric complex ([RAG14:RAG24]);(b) indicate that once a RAG complex brings two RSS sites into synapsis, the synaptic complex rarely disassembles (nearly irreversible); (c) predict that binding of both RSS sites (synapsis) occurs before catalysis (nicking); and (d) show that RAG binding properties permit strong distinction between RSS sites within active chromatin versus non-specific DNA or RSS sites within inactive chromatin, a point with evolutionary implications. The results provide insights for synapsis by nuclear proteins generally and testable predictions.