We developed a chondroitin sulfate - polyethylene glycol (CS-PEG) adhesive hydrogel with numerous potential biomedical applications. The carboxyl groups on chondroitin sulfate (CS) chains were functionalized with N-hydroxysuccinimide (NHS) to yield chondroitin sulfate succinimidyl succinate (CS-NHS). Following purification, the CS-NHS molecule can react with primary amines to form amide bonds. Hence, using six arm polyethylene glycol amine PEG-(NH2)6 as a crosslinker we formed a hydrogel which was covalently bound to proteins in tissue via amide bonds. By varying the initial pH of the precursor solutions, the hydrogel stiffness, swelling properties, and kinetics of gelation could be controlled. The sealing/adhesive strength could also be modified by varying the damping and storage modulus properties of the material. The adhesive strength of the material with cartilage tissue was shown to be ten times higher than that of fibrin glue. Cells encapsulated or in direct contact with the material remained viable and metabolically active. Furthermore, CS-PEG material produced minimal inflammatory response when implanted subcutaneously in a rat model and enzymatic degradation was demonstrated in vitro. This work establishes an adhesive hydrogel derived from biological and synthetic components with potential application in wound healing and regenerative medicine.

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PURPOSE. To study change in choroidal thickness (CT) after water drinking test (WDT), comparing angle closure (AC) to open angle (OA) eyes.METHODS. Before and 30 minutes after drinking 1 L of water, 88 glaucoma subjects underwent measurements of CT by spectral domain-optical coherence tomography, IOP, blood pressure (BP), axial length (AL), and anterior chamber depth (ACD). RESULTS.Baseline CT was significantly greater in AC than in OA eyes (P ¼ 0.002). After WDT, BP, IOP, and AL increased significantly (all P 0.0001). Mean CT increased significantly in the AC group (5.6 lm, P ¼ 0.04, n ¼ 40) and among 80 subjects whose IOP rose > 2 mm Hg (responders; 3.2 lm, P ¼ 0.048), but not in the OA group or among all subjects (2.5 lm increase overall, <1% of baseline CT, P ¼ 0.10). ACD decreased in AC (À18 lm, P ¼ 0.07), but not in OA eyes (þ3 lm, P ¼ 0.74). AC eyes had a significantly greater IOP increase after WDT than OA eyes (P ¼ 0.002, multivariate regression). Among responders, CT increased more in those with larger diastolic perfusion pressure increase and in AC compared to OA eyes (P ¼ 0.04 and P ¼ 0.053, respectively, multivariate regression).CONCLUSIONS. A significant increase in CT and a decrease in ACD after WDT were observed in AC but not in OA eyes, and IOP increased significantly more in AC than in OA eyes, suggesting that the dynamic behavior of the choroid may play a role in the AC process. IOP increase after the WDT was not fully explained by CT increase. (Invest Ophthalmol Vis Sci. 2012; 53:6393-6402)

AC eyes had significantly thicker CT than OA and normal eyes, even after adjusting for the shorter AL in AC eyes, supporting hypotheses that choroidal expansion contributes to the development of AC disease. Age, AL, CCT, and IOP were also significantly associated with CT, while severity of glaucoma damage was not.