ABSTRACT
Sutureless joining of tissue surfaces has been a long-sought goal because use of sutures induces inflammation and subsequent fibrosis and may leave gaps between suture points. Light-initiated techniques to bond tissues together were introduced over 30 years ago. Ideally, these approaches produce a strong, immediate, watertight bond without damage to adjacent tissue that maintains its strength over a long period. Such techniques might be especially appropriate for microsurgery since they circumvent the need for skilled placement of hair-fine sutures in small delicate structures. Two approaches, differing in mechanism, have been developed for light-initiated tissue bonding. The first method developed operates by a thermal mechanism involving rapid absorption of laser energy at the junction of the tissues and a temperature rise above the denaturation temperature of collagen. The partially denatured collagen molecules are believed to interact and intertwine so that, upon cooling, a continuous seal forms. The second mechanism involves photochemical reactions that initiate formation of covalent cross-links between collagen molecules on the tissue surfaces. Photochemical cross-linking can occur without a temperature increase or protein denaturation, and it produces a continuous molecular level seal between the two surfaces. This review focuses on tissue bonding by photochemical cross-linking.
