Majd Shervin, Yuan Youling, Mishra Sanjay, Haggard Warren O, Bumgardner Joel D
Department of Biomedical Engineering, Herff College of Engineering, University of Memphis, Memphis, Tennessee 38152, USA.
J Biomed Mater Res B Appl Biomater. 2009 Jul;90(1):283-9. doi: 10.1002/jbm.b.31284.
The influence of degree of deacetylation (DDA), molecular weight (MW), and heat treatment on nanomechanical properties of three different chitosan coatings was assessed. Chitosans (2.5 wt % in 2% acetic acid) were solution cast and bonded to glass slides, subjected to 40, 70, or 90 degrees C heat treatments for 1 h, and then allowed to air dry. Non-heat treated films were used as controls. The nanomechanical and structural properties were evaluated using quasi-static nanoindentation, X-ray diffraction (XRD), and atomic force microscopy (AFM). Nanoindentation results showed that the coating with the lowest MW and highest DDA (95.6% DDA and MW = 2.43 x 10(6) Da) had higher reduced modulus of elasticity, (E = 4.02 +/- 0.85 GPa) as compared to the other chitosans; 76.1% DDA/MW = 3.20 x 10(6) Da, E = 3.66 +/- 0.68 GPa, and 92.3% DDA/MW = 7.52 x 10(6) Da, E = 3.56 +/- 0.25 GPa; (n = 75, p < 0.05). Crystallinity index, estimated via XRD, ranged from 36.4% +/- 1% to 49.7% +/- 6.5%. AFM revealed the presence of different crystalline morphologies such as needle-like crystals, sheet-like crystals, and small spherulites. The heat treatments applied during solution casting of the chitosan coatings did not affect morphology or nanomechanical properties. In conclusion, nanomechanical properties of chitosan coatings varied with DDA and MW and may be important to cell/tissue interactions.
评估了脱乙酰度（DDA）、分子量（MW）和热处理对三种不同壳聚糖涂层纳米力学性能的影响。将壳聚糖（在2%乙酸中为2.5 wt%）溶液浇铸并粘结到载玻片上，分别在40、70或90摄氏度下热处理1小时，然后自然风干。未热处理的薄膜用作对照。使用准静态纳米压痕、X射线衍射（XRD）和原子力显微镜（AFM）评估纳米力学和结构性能。纳米压痕结果表明，与其他壳聚糖相比，MW最低且DDA最高（95.6% DDA和MW = 2.43×10⁶ Da）的涂层具有更高的折合弹性模量（E = 4.02±0.85 GPa）；76.1% DDA/MW = 3.20×10⁶ Da，E = 3.66±0.68 GPa，以及92.3% DDA/MW = 7.52×10⁶ Da，E = 3.56±0.25 GPa；（n = 75，p < 0.05）。通过XRD估计的结晶度指数范围为36.4%±1%至49.7%±6.5%。AFM揭示了不同的晶体形态，如针状晶体、片状晶体和小球晶。壳聚糖涂层溶液浇铸过程中进行的热处理未影响形态或纳米力学性能。总之，壳聚糖涂层的纳米力学性能随DDA和MW而变化，可能对细胞/组织相互作用很重要。
