Gelation of dilute collagen solutions by ultraviolet light

Abstract

SynopsisDilute collagen and collagen-polymer solutions were irradiated at 4OC with UV light (254 nm) under a nitrogen atmmphere. The collagen had been recovered from native tissue by a process of simultaneous acid solubilization together with proctase treatment to remove telopeptides. In the range of concentrations studied (0.1% to 0.9% collagen), gelation occurs after a few minutes, and the dynamic mechanical properties are followed thereafter using a freely oscillating torsion pendulum. During the irradiation, crosslinking and scission reactions compete. Initially crosslinking reactions dominate and the storage modulus increases. However, with extensive irradiation, scission reactions become important, and the storage modulus passes through a maximum and finally decreases. Furthermore, the time for incipient gelation decreases with concentration, and the maximum storage modulus increases with concentration to the 2.5.power for collagen solutions. As an example, the maximum storage modulus for a 0.5% solution is l . l X l o 4 dynes/cm*. The moduludose behavior can be reduced to a single relationship in which the ratio of modulus to maximum modulus is a function of dose divided by dose to reach the maximum modulus.

Resurfacing damaged articular cartilage to restore compressive properties

“…Numerous chemicals such as glutaraldehyde, carbodiimide and tannic acid have been used to directly crosslink collagen, however their cytotoxicity and potential harmful side effects exclude most from in vivo use. On the other hand, photocrosslinking collagen using UV irradiation (Hamed and Rodriguez, 1975; Weadock et al 1995), photo-oxidative dyes and initiators (RF, IRG, hematoporphyrin) (Wollensak et al 2003a; Moore at al. 1994), and a variety of biopolymers (CS, HA, alginate, polyethylene glycol, fibrin, fibronectin) (Lee et al 2001a; Stalling et al 2009; Erickson et al 2012) which can be entrapped or crosslinked after incorporating functional groups such as methacrylate, thiolate or tyramine have been shown to be efficacious and biocompatible with controlled cytotoxicity levels when used in cell culture, animal and human studies (Akens et al, 2002; von Rechenberg et al, 2004; Bryant et al, 2000; Sharma et al, 2013).…”

Fracture behavior and morphology of spun collagen fibers

“…16 Schimpf and Rodriguez described that tensile strength shows the maximum value when the fibers are treated at 0.2% GA concentration and then decreases due to the competing crosslink and chain scission mechan i s m~.~ The structure and mechanical properties of the collagen fiber from pepsin-soluble collagen were also reported by Utsuo and T a n i g u~h i .~,~. '~ However, there has been no detailed studies on the fracture mechanism of the spun collagen fibers from a viewpoint of fracture morphology comparing GA-crosslinked fibers with basic chromium sulfate ( Cr ) tanning fibers.…”