β-Lactoglobulin (BLG) binding to highly charged cationic polymer-grafted magnetic nanoparticles: effect of ionic strength

Li Qin; Yisheng Xu; Haoya Han; Miaomiao Liu; Kaimin Chen; Siyi Wang; Jie Wang; Jun Xu; Li Li; Xuhong Guo

doi:10.1016/j.jcis.2015.08.056

β-Lactoglobulin (BLG) binding to highly charged cationic polymer-grafted magnetic nanoparticles: effect of ionic strength

J Colloid Interface Sci. 2015 Dec 15:460:221-9. doi: 10.1016/j.jcis.2015.08.056. Epub 2015 Aug 24.

Authors

Li Qin¹, Yisheng Xu², Haoya Han¹, Miaomiao Liu¹, Kaimin Chen³, Siyi Wang⁴, Jie Wang¹, Jun Xu¹, Li Li¹, Xuhong Guo⁵

Affiliations

¹ State Key Laboratory of Chemical Engineering, East China University of Science and Technology, Shanghai 200237, China.
² State Key Laboratory of Chemical Engineering, East China University of Science and Technology, Shanghai 200237, China; School of Chemistry and Chemical Engineering, Shihezi University, Shihezi 832003, China. Electronic address: yshxu@ecust.edu.cn.
³ College of Chemistry and Chemical Engineering, Shanghai University of Engineering Science, Shanghai 201620, China.
⁴ Testing Center, Shanghai Research Institute of Chemical Industry, Shanghai 200062, China.
⁵ State Key Laboratory of Chemical Engineering, East China University of Science and Technology, Shanghai 200237, China; School of Chemistry and Chemical Engineering, Shihezi University, Shihezi 832003, China. Electronic address: guoxuhong@ecust.edu.cn.

PMID: 26322494
DOI: 10.1016/j.jcis.2015.08.056

Abstract

Poly(2-(methacryloyloxy)ethyltrimethyl ammonium chloride) (PMATAC) modified magnetic nanoparticles (NPs) with a high zeta potential of ca. 50mV were synthesized by atom transfer radical polymerization (ATRP). The prepared NPs consist of a magnetic core around 13nm and a PMATAC shell around 20nm attached on the surface of magnetic nanoparticles. Thermodynamic binding parameters between β-lactoglobulin and these polycationic NPs were investigated at different ionic strengths by high-resolution turbidimetry, dynamic light scattering (DLS), and isothermal titration calorimetry (ITC). Both turbidity and ITC show that binding affinities for BLG display a non-monotonic ionic strength dependence trend and a maximum appears at ionic strength of 50mM. Such observation should arise from the coeffects of protein charge anisotropy visualized by DelPhi electrostatic modeling and the strong electrostatic repulsion among highly charged NPs at a variety of ionic strengths.

Keywords: Cationic polymer shell; Ionic strength; Magnetic nanoparticles; Protein binding; β-Lactoglobulin.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Animals
Anisotropy
Calorimetry
Cations / chemistry*
Cattle
Hydrogen-Ion Concentration
Ions
Kinetics
Lactoglobulins / chemistry*
Light
Magnetite Nanoparticles / chemistry*
Microscopy, Electron, Transmission
Nanotechnology / methods
Nephelometry and Turbidimetry
Osmolar Concentration
Polymers / chemistry*
Protein Binding
Scattering, Radiation
Static Electricity
Thermodynamics
X-Ray Diffraction

Substances

Cations
Ions
Lactoglobulins
Magnetite Nanoparticles
Polymers