Morphological property and in vitro enzymatic degradation of modified chitosan as a scaffold

Abstract

Chitosan (CS) was proposed as a promising candidate scaffold for tissue engineering. However, some drawbacks of natural CS remain. The current study modified CS by conjugating thiol to CS polymer (Thio-CS) and substantiated its three-dimensional microstructure and physical properties such as swelling or degradation. The Thio-CS was obtained by CS modification using 2-iminothiolane-HCl (2-IT). Because of the formation of disulfide bonds between thiol moieties based on oxidation of the immobilized thiol groups of CS, Thio-CS exhibits in situ gelling properties according to the reducing amount of free thiol. The content of the thiol group was increased as the amount of 2-IT increased. The swelling test demonstrated that Thio-CS can absorb up to 3.5 times its weight of phosphate buffered saline within 1 h and that the pore size and amount significantly increased with incubation time. The Thio-CS enzymatic degradation rate according to velocity was investigated. The results showed that Thio-CS was more resistant to lysozyme as viscosity increased. Thio-CS sponges were fabricated using freezedrying. The lyophilized Thio-CS had a homogeneous honeycomb-like shape, and its pores were relatively smaller (<2 µm) than those of unmodified CS (>2 µm). These results suggest that Thio-CS might be a candidate regenerative therapeutic device.

Evaluation of a Thiolated Chitosan Scaffold for Local Delivery of BMP-2 for Osteogenic Differentiation and Ectopic Bone Formation

“…This is consistent with previous report that pore size of substance has direct relationship with the molecular weight of materials [38]. As we reported previously, the optimum ratio between 2-IT and CS for the formation of disulfide bonds is 0.1 mg/mL and 1% (w/v) [34]. However, this ratio does not take account of the air-oxidation time, which can affect the formation of disulfide bonds between CS polymers.…”

“…The enhanced bone formation in Thio-CS-B2 might result from more superior property of Thio-CS than Col-gel for bone formation. In our previous report [34], Col-gel showed the limited swelling property with scant physical change of the porosity, suggesting limiting the capacity to absorb BMP-2. The present study also showed that Col-gel-B2 has the burst release pattern of BMP-2 compared with Thio-CS-B2.…”

“…Based on previous physicochemical properties of Thio-CS (Figure 1 and [34]), it is expected to delay the velocity of the release of BMP-2. Therefore, the release kinetics of BMP-2 from Thio-CS were measured for 28 days and compared with those of the Col-gel, which is widely used in the delivery of BMP-2 (Figure 2(c)).…”

“…We have previously reported the optimal conditions for fabricating Thio-CS [34]. In brief, the pH of a mixture containing a 1% solution of CS and 0.1 mg/mL of 2-IT was adjusted, ranging from 4 to 12.…”

“…Ellman's reagent (3 mg of 5,5′-dithiobis (2-nitrobenzoic acid)) (Sigma, St. Louis, MO, USA) was used to quantify the amount of thiol groups on the modified CS, as described previously [34]. Briefly, 5 mg of the freeze-dried samples was dissolved in 2.5 mL of demineralized water.…”