Interaction of Polyethyleneimine-Functionalized ZnO Nanoparticles with Bovine Serum Albumin

Abstract

In biological fluids, nanoparticles are always surrounded by proteins. As the protein is adsorbed on the surface, the extent of adsorption and the effect on the protein conformation and stability are dependent on the chemical nature, shape, and size of the nanoparticle (NP). We have carried out a detailed investigation on the interaction of bovine serum albumin (BSA) with polyethyleneimine-functionalized ZnO nanoparticles (ZnO-PEI). ZnO-PEI was synthesized using a wet chemical method with a core size of ~3-7 nm (from transmission electron microscopy). The interaction of BSA with ZnO-PEI was examined using a combination of calorimetric, spectroscopic, and computational techniques. The binding was studied by ITC (isothermal titration calorimetry), and the result revealed that the complexation is enthalpy-driven, indicating the possible involvement of electrostatic interaction. To investigate the nature of the interaction and the location of the binding site, a detailed domain-wise surface electrostatic potential calculation was performed using adaptive Poisson-Boltzmann software (APBS). The result shows that the protein surface can bind the nanoparticle. On binding ZnO-PEI, the protein gets destabilized to some extent, as displayed by CD (circular dichroism) and FTIR (Fourier transform infrared) spectroscopy. Chemical and thermal denaturation of BSA, when carried out in the presence of ZnO-PEI, also indicated a small perturbation in the protein structure. A comparison of the enthalpy and entropy components of binding with those derived for the interaction of BSA with ZnO nanoparticles explains the effect of hydrophilic cationic species attached on the NP surface. The effect of the NP surface modification on the structure and stability of BSA would find useful applications in nanobiotechnology.

Nanoparticle–Cell Interactions: Molecular Structure of the Protein Corona and Cellular Outcomes

“…52,59−61 A similar disruption of protein structure has been observed previously for NPs. 62−67 In the case of albumin, disruption of secondary structure has been observed following adsorption to silver NPs, 42,68 zinc oxide NPs, 69 gold NPs, 44,70,71 and gold nanorods. 44 Structural changes have also been observed for lower abundance plasma proteins including fibrinogen, 27,46,71 lysozyme, 72 cytochrome c , 73,74 and chymotrypsin.…”

Zinc oxide nanoparticle and bovine serum albumin interaction and nanoparticles influence on cytotoxicity in vitro

“…BSA has two Trp residues at positions 134 and 212. Trp212 residue is located in the largest hydrophobic cavity of the protein known as Sudlow"s site I, whereas Trp134 is located on the surface of the subdomain Ib [18]. If the binding occur to any of these domains and changes the microenvironment (hydrophobicity) of Trp, the shift in fluorescence maximum is observed.…”

“…ZnO NPs were covalently and non-covalently coated with BSA at 4°C and 20°C. These temperatures are usually used in similar studies for NP coating [17,6,18]. ZnO NP-induced changes in BSA structure and consequent effect of protein-coated NPs on the viability and reactive oxygen species (ROS) generation in Chinese hamster ovary (CHO) cells grown in vitro were investigated.…”

Effects of size and surface functionalization of zinc oxide (ZnO) particles on interactions with bovine serum albumin (BSA)

“…In the other hand, for the functionalized MW, BSA is anchored by hydrogen bonds between -SH and different possible connection points of BSA. Similarly, some differences in interactions between BSA and ZnO nanoparticles and BSA and polyethyleneiminefunctionalized ZnO nanoparticles were reported in [27].…”

“…For ZnO NP of 7.5 nm of diameter, the formation of aggregates of BSA-ZnO NP induces some conformational modification of BSA [26]. In [27] very little alterations in the ellipticity values in BSA circular dichroism (CD) spectrum were found on binding to 6 nm diameter NP of ZnO functionalized with polyethyleneimine (PEI), suggesting only a minor change in the three-dimensional configuration of the protein.…”