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A novel method to prepare crosslinked polyethyleneimine (CPEI) hollow nanospheres was reported. Uniform silica nanospheres were used as templates, 3-aminopropyl trimethoxysilane (APS) was immobilized on the surface of silica nanospheres as couple agent. Aziridine was initiated ring-opening polymerization with the amino groups in APS to form polyethyleneimine (PEI) shell layer. 1,4-Butanediol diacrylate was utilized to crosslink PEI polymeric shell. The silica nanospheres in core were etched by hydrofluoric acid to obtain hollow CPEI nanospheres. The hollow nanospheres were characterized by X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), and thermogravimetric analysis (TGA).

Chitosan membranes were prepared by a thermal induced phase separation method, following treatment with nontoxic NaOH gelating and Na₅P₃O₁₀, Na₅SO₃ crosslinking agents. Effects of these reaction agents on chitosan membranes were evaluated to survey the feasibility of using these membranes in guided tissue regeneration (GTR) application. The preliminary results showed chitosan membranes crosslinked with Na₅P₃O₁₀ and Na₂SO₃ had gel content of 53.5% and 52.2%r, respectively. Contrarily, the chitosan matrix gelated with NaOH dissolved completely during gel content measurement. Chitosan membrane treated with Na₅P₃O₁₀ had lowest elastic modulus of 12.9 Mpa as compared with other membranes treated with Na₂SO₃ (17.9Mpa) and NaOH(23.6Mpa). From SEM observations, NaOH gelated chitosan membrane had the smoothest surface morphology than others. However, Na₅P₃O₁₀ crosslinked chitosan membrane had better cell adhesion and proliferation results in cell culture test. All three chitosan membranes degraded by about 23%∼28% of initial weight after a 90-day in vitro shaking test.

With an attempt to expand the versatilities and applications in chitosan microspheres, chitosan were first converted into micro-droplets by using a high voltage electrostatic field system, and then treated with Na₅P₃O₁₀/NaOH solution of volume ratio of 17/3, 19/1, 1/0 (pure Na₅P₃O₁₀) or 0/1 (pure NaOH) to fabricate chitosan microsphere. By varying the pH values of these reacting agents, distinct morphological structures and properties of chitosan microspheres were further be changed. Chitosan microsphere prepared in this study exhibited a good spherical shape and was in a range of 185.8 ± 13.8 μm to 380.9 ± 11.5 μm in diameter. The size of chitosan microspheres varied by treating with various pH values of these reaction reagents. The prepared chitosan microspheres upon treatment with pH 7 of various ratios Na₅P₃O₁₀/NaOH solution, all exhibited a shrunken surface morphological structure. This densely shrunken structure of microspheres yielded a stronger mechanical strength and a slower release rate of drug (5-FU), no matter what the ratios of Na₅P₃O₁₀/NaOH solution was used. From the data of FTIR analyses, the protonated amino peak of NH₃⁺ at around 1562 cm⁻¹ has decreased significantly after treated with various pH values of these reaction reagents. It could be attributed to the linkage between phosphoric and ammonium ion of the protonated chitosan molecules. Besides, another boarder absorption at about 3366cm⁻¹ of treated chitosan microspheres (under the employed range of pH values), which represented the hydrogen bonding was enhanced as compare with the pure chitosan material.