中文摘要：

通过电导返滴定法测定经强酸氧化后的荧光纳米钻石（FND,约140 nm）表面羧基含量为126μmol/g,占表面原子数的29.7%.对FND物理吸附人转铁蛋白（hTf）进行了研究,其吸附行为符合Langmuir等温吸附,在PBS（pH 7.4）中最大吸附量为（176.46±2.13）μg/mg,同时研究了pH对FND吸附hTf的影响,发现在pH等于hTf的等电点附近有最大吸附.利用激光共聚焦和流式细胞仪对FND和FND-hTf内吞到人肝癌细胞（HepG2）的差异进行了定性和定量分析,结果得到FND-hTf比FND容易内吞到细胞中,利于胞内成像.

英文摘要：

Nanodiamond （ND）, as a member of carbon nanomaterials family, has recently received increasing attention for their potential applications as imaging and drug delivery agents. Due to several charming properties, such as surface func- tionalization capability, biocompatibility and chemical stability, ND demonstrates high affinity to biomolecules. In this work, the adsorptive behavior of oxidized fluorescent nanodiamond （FND, with a size of ca. 140 nm） for hTfwas investigated. The amount of surface carboxytic acid on oxidized FND was 126 ~tmol/g determined by conductometric backward titration. This amount is 29.7% of the total surface atoms. HTf physically adsorbed on the surface of FND （FND-hTf） in PBS （pH7.4） shows that the isothermyal adsorption behavior is coincident with Langmuir model and the maximum adsorbed amount is （176.46±2.13）μg/mg. ND coated human transferrin （hTf） can improve the dispersity and stability compared to pristine FND under a physiological environment or in cell culture medium observed through optical microscope and be more suitable for biomedicine applications. Simultaneously, pH effect on hTf adsorbed onto FND is also inquiried. The result exhibits that FND has the greatest adsorption capacity for hTf close to the isoelectric point. Owing to the negatively charged nitrogen- vacancy （N-V）- defect centers, FND can absorb strongly at ca. 560 nm and emit fluorescence efficiently at ca. 700 nm, which can be well quantitatively and qualitatively analyzed by flow cytometry and confocal fluorescence images. In vitro experiments of human liver cancer cells （HepG2） uptake of nanoparticles display that FND-hTf nanoparticles are more easily endocytosed than that of pristine FND. So FND-hTf is conducive to cell imaging. Furthermore, flow cytometry assay indi- cates cellular uptake of FND-hTf reached a plateau at about 8 h and the uptake half-life is about （1.41±0.22） h at a particle concentration of 100 μg/mL. The results obtained by confocal fluorescent images d