Preparation of carboxyl-functionalized silica core-shell microspheres and their applications in weak cation exchange chromatography, heavy metal removal, and lysozyme enrichment.

Chromatography is a technique of separation based on adsorption and/or interaction of target molecules with stationary phases. Herein, we report the design and fabrication of BTDA@SiO2 core-shell microspheres as a new class of stationary phase and demonstrate its impressive performance for chromatographic separations. The silica microspheres of BTDA@SiO2 were synthesized by in situ method with 1,3,5-benzenetricarboxaldehyde and 3,5-diaminobenzoic to separate peptides and proteins on high-performance liquid chromatography. The BTDA@SiO2 core-shell structure has a high specific surface area and retention factor of 4.27 and 8.31 for anionic and cationic peptides, respectively. The separation factor and resolution were high as well. A typical chromatogram illustrated nearly baseline resolution of the two peptides in less than 3 min. The BTDA@SiO2 was also highly stable in the pH range of 1 to 14. Furthermore, the prepared BTDA@SiO2 core-shell material not only be used for chromatographic separation but also as heavy metal removal from water. Using a BTDA@SiO2, we also achieved a lysozyme enrichment with a maximum saturated adsorption capacity reaching 714 mg/g. In summary, BTDA@SiO2 has great application prospects and significance in separation and purification systems.

Synthesis of core-shell material rich in carboxyl groups and its application in the selective adsorption of cationic peptides.

The ability to extract peptides and proteins from biological samples with excellent reusability, high adsorption capacity, and great selectivity is essential in scientific research and medical applications. Inspired by the advantages of core-shell materials, we fabricated a core-shell material using amino-functionalized silica as the core. Benzene-1,3,5-tricarbaldehyde and 3,5-diaminobenzoic acid were used as model organic ligands to construct a shell coating by alternately reacting the two monomers on the surface of silica microspheres. The resultant material featured an outstanding capability for the adsorption of cationic peptides, most likely owing to its porous structure, a large number of carboxylic functional groups, and low mass-transfer resistance. The maximum saturated adsorption capacity reached 833.3 mg/g and the adsorption process took only 20 min. Under optimized adsorption conditions, the core-shell material was used to selectively adsorb cationic peptides from the tryptic digestive solution of lysozyme and bovine serum albumin, Specifically, the analysis results showed seven cationic peptides in the eluate and twenty anionic peptides in the supernatant, which indicates the efficient trap of most cationic peptides in the digestive solution.