Boronic Acid Functionalized Nanosilica for Binding Guest Molecules.

Xiaoting Xue,Lei Ye,Hongwei Zheng,Haiyue Gong

doi:10.1021/acsanm.1c00005

Abstract

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 cis-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 cis-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.

Highlights

In the last decades, mesoporous silica has been extensively studied in materials science for the development of new technologies.[1,2] Due to their unique properties such as high stability, good biocompatibility, and ease of surface modification, silica nanoparticles are outstanding building blocks in a wide range of applications.[3]
In this work we investigated the use of Cu(I)-catalyzed alkyne−azide cycloaddition (CuAAC) click reaction and a general-purpose polymer intermediate to immobilize affinity ligands in the nanoscale pores of dendritic fibrous nanosilica (DFNS)
Because of its unique structural characteristics, DFNS can add one additional selectivity defined by molecular sizes in addition to the wellknown boronic acid−cis-diol interactions

Summary

■ INTRODUCTION

Mesoporous silica has been extensively studied in materials science for the development of new technologies.[1,2] Due to their unique properties such as high stability, good biocompatibility, and ease of surface modification, silica nanoparticles are outstanding building blocks in a wide range of applications.[3]. Preparation of Boronic Acid Modified Copolymer Brushes Grafted on Dendritic Fibrous Silica (DFNS@pco@BA). The obtained particles (DFNS@pco@N3, 50 mg) dispersed in a mixture of methanol (5 mL) and water (5 mL) were mixed with 2 mL of methanol containing PCAPBA (50 mg). For proof of successful introduction of boronic acid into the mesoporous silica particles, boronic acid functionalized nanoparticles (1 mg) and 1 mL of 0.1 mM ARS solution (prepared in 20 mM pH 8.5 PBS buffer containing 0.5 M NaCl) were mixed and shaken for 1 h. 0.5 mL of boronic acid modified nanoparticles in suspension was mixed with 0.5 mL of ARS solution at different pHs. The samples were gently shaken at 20 °C for 1 h. Samples were heated to 900 °C at a rate of 10 °C/min in synthetic air

■ RESULTS AND DISCUSSION

■ CONCLUSION

■ REFERENCES