Suturing is the clinical standard for nerve approximation (joining epineurium and outer layer of both ends of transected nerve) but can cause neuroma (cyst formation by irregular growth of nerves), asymmetric tension of nerve and time-consuming process for nerve surgeons; usually epineural suturing takes 2-6 hours. Glue and sealants have been explored as suture less alternatives in nerve repair, but often suffer from inadequate and inconsistent nerve joining (dehiscence), rigidity and cytotoxicity. Generation of sealants which can overcome the drawbacks associated with existed glues and films to improve the repair outcomes in peripheral nerve injuries are in demand in surgical medicine. Near-infrared laser-activated adhesives (NILAAs) provide suture-less, fast, and precise tension-free nerve repair based on demonstrated significant advantages of this approach for soft tissue repair. NILAAs can be generated using a biomaterial like chitosan, silk and gelatin etc. or any functionally modified these basic biopolymers formulated by mixing with an FDA-approved near-infrared absorbing dye indocyanine green (ICG) as NILAA for end-to-end approximation of transected nerves. These newly generated NILAAs can be analyzed for their mechanical strength, elasticity nature and nerve tissue adhesion potentials then followed by in vivo sealing with sciatic nerve transverse cut in Rats. Mostly, crush and transection injuries are common nerve injuries have been observed due to combat and accidents. These defects which cannot be repaired with direct end-to-end approximation due to loss of functional nerve matter. Artificial grafts (e.g., NEUROLAC) commonly known as synthetic nerve conduits are the best alternative for bridging the peripheral nerve defects. NILAAs will also be effective to place a nerve conduit for a significant nerve gap (~1cm) and helps to regenerate both ends to meet each other.
However, the NILAAs properties mainly influenced by the chemical functional groups present on various biomaterials used in the preparation, and which is also significant in the nerve tissue adhesion. In view of this feature, we prepared different functionalized like thiol, catechol, trimethyl ammonium and carboxylic acid containing chitosan materials and used for preparation of NILAAs. Initially, these different NILAAs are screened for their nerve tissue adhesion potentials using ultimate tensile strength (UTS) in porcine transverse full cut sciatic nerve ex vivo model. The better candidates of all the varieties of NILAAs will be used for in vivo sciatic nerve approximation with and without nerve conduits. Eventually, generation of better alternate for suture less nerve surgery in the name of NILAAs is hypothesized and would be optimized.
