[Preparation and physicochemical property of carboxymethyl-chitosan/hyaluronic acid poly(vinyl alcohol) blend membrane].

OBJECTIVE: To prepare carboxymethyl-chitosan/hyaluronic acid/poly(vinyl alcohol) (CHP) blend membrane, evaluate its physicochemical properties and intraocular biocompatibility and to investigate its feasibility to be applied to glaucoma filtering surgery.

METHODS: CHP blend membrane was prepared using solution casting method after blending carboxymethyl-chitosan, HA and poly(vinyl alcohol) in a proportion of 5 : 4 : 1 (M/M). Its water absorption rate, swelling rate, permeability, and mechanical properties were detected. Subconjunctival fibroblasts separated from subconjunctival tissue of New Zealand white rabbits were cultured, and the cells at passage 4 were cultured on cell culture plate with or without the CHP blend membrane, serving as the experimental group and the control group, respectively. Effect of the CHP blend membrane on the subconjunctival fibroblasts was tested by MTT method 24, 48, and 72 hours after culture. Six New Zealand white rabbits were randomly divided into two groups (n = 3 rabbits per group), and the CHP blend membrane and SK gel were implanted into the rabbits' subconjunctival space and anterior chamber in the experimental group and the control group, respectively. Slit lamp observation and binocular reaction record were conducted 1, 3, 5, 9, 11, 20, 30, 45, and 60 days after operation. Corneal tissue harvested from the experimental group was observed using scanning electron microscope 15 days after operation to study ophthalmic biocompatibility and biodegradability.

RESULTS: The water absorption rate and the swelling rate of the CHP blend membrane was 83.8% +/- 1.3% and 3.59 +/- 0.50, respectively. The tensile strength of the dry and the wet CHP blend membrane was (20.59 +/- 1.73) and (0.51 +/- 0.13) MPa, respectively. The breaking elongation rate of the dry and the wet CHP blend membrane was 10.69% +/- 1.16% and 53.15% +/- 2.46%, respectively. The CHP blend membrane had good permeability to NaCl and L-tyrosine. Absorbance (A) value of the experimental group 24, 48, and 72 hours after breeding was 0.207 +/- 0.083, 0.174 +/- 0.080, and 0.181 +/- 0.048, respectively, while the A value of the control group was 0.284 +/- 0.011, 0.272 +/- 0.083, and 0.307 +/- 0.056, respectively. Significant difference was evident between two groups (P < 0.05). In the experimental group, a small amount of floccus was exuded around the implanted membrane 1 day after operation; the floccus was absorbed on the third day, and there was no obvious inflammatory reaction occurring on the eleventh day. Most of the membrane degraded on the sixtieth day. Scanning electron microscope observation showed that the hexagonal morphology of the corneal endothelial cells was intact, and no degradation particles adhered to the surface. In the control group, the implantation of SK gel into anterior chamber was unsuccessful because the SK gel was quite soft and easily broken. In the experimental group, mild hyperemia emerged around the implanted membrane 1 day after the subconjunctival implantation of the membrane, and it became normal on the ninth day. No corneal edema and inflammatory reaction of anterior chamber occurred till the sixtieth day. The results in the control group and the experiment group were similar.

CONCLUSION: Due to its good physicochemical properties and biocompatibility, the CHP blend membrane has potential applications in glaucoma filtering surgery.