Peparation of Magnetic Nanoclusters for Efficient Selective Protein Adsorption

Abstract

Event Abstract Back to Event Peparation of Magnetic Nanoclusters for Efficient Selective Protein Adsorption Fang Lan1, Qi Yang1, Yao Wu1* and Zhongwei Gu1* 1 Sichuan University, National Engineering Research Center for Biomaterials, China Introduction: The efficient adsorption of protein from a complex mixture is of great significance in proteomics and diagnostics. Magnetic nanoparticless have widely applied in the biomedical field especially in protein separation due to unique superparamagnetic property [1]. In order to selectively adsorption and separation target protein, antibody and other ligands were usually immobilized onto the surface of magnetic nanoparticles [2]. However, most ligands are either expensive or inconvenient to obtain. Although several clever strategies have been reported to resolve this problem, these systems still suffer from drawbacks including low magnetic content, low saturation magnetization, complicated synthesis routes, and severe aggregation of nanomaterials. Therefore, the development of a facile yet efficient strategy for selective proteinadsorption is highly desirable. Materials & Methods: We proposed a new kind of ligand-free Fe3O4/carboxymethylated chitosan (Fe3O4/CMCS) nanoclusters with high negative charges by a combination method of inverse emulsion crosslinking approach and assembly technique. Firstly, the Fe3O4 nanoparticles which were prepared by co-precipitation were stabled with CMCS to obtain Fe3O4/CMCS nanospheres as assembly units. Then, the Fe3O4/CMCS composite nanospheres were assemblied and cross-linked with genipin in liquid paraffin to successfully prepare Fe3O4/CMCS nanoclusters. To evaluate selective protein adsorption capacity of the ligand-free Fe3O4/CMCS nanoclusters without any further functionalization, lysozyme (LYZ), bovine serum albumin (BSA), bovine hemoglobin (BHB), apo-transferrin (TRT), myoglobin (MB) were used as model proteins. The ligand-free Fe3O4/CMCS nanoclusters were incubated with a protein mixture. For selective adsorption of BHB from biological samples, the ligand-free Fe3O4/CMCS nanoclusters were incubated with 10% fetal bovine serum (FBS) diluted with Dulbecco’s modified Eagle’s medium (DMEM) cell culture medium. Results & Discussion: The Fe3O4/CMCS nanoclusters presented a spherical shape of around 500 nm and the size distribution was narrow. The surface of the Fe3O4/CMCS nanoclusters had high negative charges at a wide pH ranging from pH 5-11, demonstrating stability of the Fe3O4/CMCS nanoclusters. Such nanoclusters exhibited superparamagnetism at room temperature due to negligible coercivity and remanence and high saturation magnetization. In suspension solution, the Fe3O4/CMCS nanoclusters could respond rapidly to the external magnet (about 200 mT) within 10 s and could be re-dispersed in water by gently shaking once the external magnet was removed. The results of protein experaments showed the ligand-free Fe3O4/CMCS nanoclusters could highly selectively adsorb BHB in a protein mixture. Moreover, the ligand-free Fe3O4/CMCS nanoclusters exhibted excellent BHB selective adsorption capacity in FBS. We futher studied the mechanism of high selective adsorption of BHB. Interestingly, we found that the ligand-free Fe3O4/CMCS nanoclusters could highly effectively selectively adsorb proteins structurally similar to BHB (e. g. chymotrypsin (CTP), lysozyme (LYZ)). Both the high negative charges on the surface of Fe3O4/CMCS nanoclusters and unique structure of proteins influence on highly selectively protein adsoption. Conclusions: We have successfully fabricated ligand-free high-magnetic-content Fe3O4/CMCS nanoclusters. The ligand-free magnetic nanoclusters possessed excellent properties would be used as a potential platform for selective protein adsorption.