Department of Mechanical Engineering, University of Minnesota, Minneapolis, Minnesota 55455, USA.
J Chem Phys. 2019 Dec 7;151(21):211103. doi: 10.1063/1.5128608.
Silicon nanocrystals are intriguing materials for biomedical imaging applications because of their unique optical properties and biological compatibility. We report a new surface functionalization route to synthesize biological buffer soluble and colloidally stable silicon nanocrystals, which is enabled by surface boron doping. Harnessing the distinctive Lewis acidic boron surface sites, postsynthetic modifications of plasma synthesized boron doped nanocrystals were carried out with polyethylene glycol (PEG-OH) ligands in dimethyl sulfoxide under photochemical conditions. The influence of PEG concentration, PEG molecular weight, and boron doping percentage on the nanocrystal solubility in a biological buffer has been investigated. The boron doping facilitates the surface functionalization via two probable pathways, by providing excellent initial dispersiblity in polar solvents and providing available acidic boron surface sites for bonding. These boron doped silicon nanocrystals have nearly identical absorption features as intrinsic silicon nanocrystals, indicating that they are promising candidates for biological imaging applications.
硅纳米晶体因其独特的光学性质和生物相容性，成为生物医学成像应用中引人关注的材料。我们报告了一种新的表面功能化方法来合成在生物缓冲液中具有可溶性和胶体稳定性的硅纳米晶体，这种方法得益于表面硼掺杂。利用硼表面独特的路易斯酸性位，在光化学条件下，采用二甲基亚砜将等离子体合成的硼掺杂纳米晶体与聚乙二醇（PEG-OH）配体进行后合成修饰。研究了 PEG 浓度、PEG 分子量和硼掺杂百分比对纳米晶体在生物缓冲液中溶解度的影响。硼掺杂通过两种可能的途径促进了表面功能化，一是在极性溶剂中提供了极好的初始分散性，二是提供了可用的酸性硼表面位用于键合。这些硼掺杂的硅纳米晶体具有与本征硅纳米晶体几乎相同的吸收特性，这表明它们是生物成像应用的有前途的候选材料。
