为了研究应用于生物细胞打印的琼脂糖凝胶的光学特性, 将不同比例的琼脂糖粉末与蒸馏水混合后加热, 溶解冷却形成不同浓度的琼脂糖凝胶。测量琼脂糖热溶液冷却过程中55 ℃时的琼脂糖溶液的折射率及琼脂糖凝胶的折射率。通过对比细胞培养液的折射率, 获得作为生物打印基质材料和生物支架的琼脂糖凝胶最佳浓度为0.786%。测量琼脂糖凝胶的可见、近红外透射光谱及衰减全反射红外吸收光谱, 结果显示琼脂糖凝胶在400~1 100 nm波段没有特征吸收峰, 而且最大吸收只有0.171Abs; 在红外波段琼脂糖凝胶的吸收特性与细胞培养液基本相同, 细胞培养液在2 966 cm-1处的特征吸收峰是培养液独有的。对琼脂糖凝胶表面的激光散射特性进行研究, 结果表明, 440 nm激光的散射最强, 532 nm激光散射最弱; 琼脂糖凝胶浓度越小, 散射越强。

Bio-printing can be described as an innovative technology that fabricates 3D functional multi-cellular tissue in vitro, namely deposited biological cells on biological scaffolds. Such efforts are being undertaken in many laboratories around the world. Agarose gel and its composite hydrogel are ideal material for scaffolds with superior biological, mechanical and structural properties. In order to research the optical properties of Agarose gel, which is applied to bio-printing, different concentration of Agarose gel were prepared by mixing up Agarose powder with distilled water in certain ratio after heating, dissolving and cooling. During the cooling procress, the refractive index of Agarose solution at 55 ℃ and Agarose gel was measured with Abbe refractometer. By comparing the refractive index of cell culture medium, the concentration of 0.007 86 g/mL was proved to be the best concentration for Agarose hydrogel as bio-printing substrate materials and biological scaffolds. Visible transmittance spectrum, near infrared transmittance spectrum and attenuated total reflectance-Fourier transform infrared spectrum of Agarose gel and cell culture medium were measured, which shows that there is no absorption peak in the spectrum of agarose gel at the wave band from 400 nm to 1 100 nm, and the maximum absorption is only 0.171 1Abs; In the range of infrared spectrum, Agarose gel has the same absorption properties with cell culture medium, except for an unique absorption property at 2 966 cm-1 in the spectrum of cell culture medium. The experiments of the laser scattering characteristic of the surface of Agarose gel show that the 440 nm laser has the strongest laser scattering intensity, while the 532 nm laser has the weakest one. Meanwhile, the smaller the concentration of Agarose gel, the stronger the scattering is.