Xue Xiaoting, Gong Haiyue, Zheng Hongwei, Ye Lei
Division of Pure and Applied Biochemistry, Department of Chemistry, Lund University, Box 124, 22100 Lund, Sweden.
ACS Appl Nano Mater. 2021 Mar 26;4(3):2866-2875. doi: 10.1021/acsanm.1c00005. Epub 2021 Feb 19.
Dendritic fibrous nanosilica (DFNS) has very high surface area and well-defined nanochannels; therefore, it is very useful as supporting material for numerous applications including catalysis, sensing, and bioseparation. Due to the highly restricted space, addition of molecular ligands to DFNS is very challenging. This work studies how ligand conjugation in nanoscale pores in DFNS can be achieved through copper-catalyzed click reaction, using an optional, in situ synthesized, temperature-responsive polymer intermediate. A clickable boronic acid is used as a model to investigate the ligand immobilization and the molecular binding characteristics of the functionalized DFNS. The morphology, composition, nanoscale pores, and specific surface area of the boronic acid functionalized nanosilica were characterized by electron microscopy, thermogravimetric and elemental analysis, Fourier transform infrared spectroscopy, and nitrogen adsorption-desorption measurements. The numbers of boronic acid molecules on the modified DFNS with and without the polymer were determined to be 0.08 and 0.68 mmol of ligand/g of DFNS, respectively. We also studied the binding of small -diol molecules in the nanoscale pores of DFNS. The boronic acid modified DFNS with the polymer intermediate exhibits higher binding capacity for Alizarin Red S and nicotinamide adenine dinucleotide than the polymer-free DFNS. The two types of boronic acid modified DFNS can bind small -diol molecules in the presence of large glycoproteins, due in large part to the effect of size exclusion provided by the nanochannels in the DFNS.
树枝状纤维纳米二氧化硅（DFNS）具有非常高的比表面积和明确的纳米通道；因此，它作为多种应用（包括催化、传感和生物分离）的支撑材料非常有用。由于空间高度受限，向DFNS中添加分子配体极具挑战性。这项工作研究了如何通过铜催化的点击反应，利用一种可选的、原位合成的温度响应聚合物中间体，在DFNS的纳米级孔隙中实现配体共轭。使用可点击的硼酸作为模型来研究配体固定化以及功能化DFNS的分子结合特性。通过电子显微镜、热重和元素分析、傅里叶变换红外光谱以及氮吸附-脱附测量对硼酸功能化纳米二氧化硅的形态、组成、纳米级孔隙和比表面积进行了表征。测定了有聚合物和无聚合物时改性DFNS上硼酸分子的数量，分别为0.08和0.68 mmol配体/克DFNS。我们还研究了DFNS纳米级孔隙中二醇小分子的结合情况。带有聚合物中间体的硼酸改性DFNS对茜素红S和烟酰胺腺嘌呤二核苷酸的结合能力高于无聚合物的DFNS。两种类型的硼酸改性DFNS在存在大糖蛋白的情况下都能结合二醇小分子，这在很大程度上归因于DFNS中纳米通道提供的尺寸排阻效应。
