Effects of surface-modifying ligands on the colloidal stability of ZnO nanoparticle dispersions in in vitro cytotoxicity test media

Abstract

The extrinsic physicochemical properties of nanoparticles (NPs), such as hydrodynamic size, surface charge, surface functional group, and colloidal stabilities, in toxicity testing media are known to have a significant influence on in vitro toxicity assessments. Therefore, interpretation of nanotoxicity test results should be based on reliable characterization of the NPs’ extrinsic properties in actual toxicity testing media. Here, we present a set of physicochemical characterization results for commercially available ZnO NPs, including core diameter, hydrodynamic diameter, surface charges, and colloidal stabilities, in two in vitro toxicity testing media (Roswell Park Memorial Institute [RPMI] and Dulbecco’s Modified Eagle’s Medium [DMEM]), as well as simple cell viability assay results for selected ZnO NPs. Four commercially available and manufactured ZnO NPs, with different core sizes, were used in this study, and their surface charge was modified with five different surface coating materials (sodium citrate, tris(2-aminoethyl)amine, poly(acrylic acid), poly(allylamine hydrochloride), and poly-L-lysine hydrochloride). The results showed that ZnO NPs were better dispersed in cell culture media via surface modification with positively or negatively charged molecules. Moreover, in the presence of fetal bovine serum (FBS) in RPMI and DMEM media, ZnO NPs were found even better dispersed for a longer period (at least 48 hours). For the HeLa cells exposed to ZnO NPs in DMEM media without FBS, surface charge-dependent cytotoxicity trends were observed, while these trends were not observed for those cells cultured in FBS-containing media. This confirmed the important roles of surface-modifying compounds and of surface charge on the resultant cytotoxicities of NPs.

Role of Charge and Size in the Translocation and Distribution of Zinc Oxide Particles in Wheat Cells

“…To obtain negatively charged ZnO NPs and bulk particles (BPs), sodium citrate was used to modify the surface. The particle coating method followed a previous study with minor modifications . Briefly, 4.0 g of ZnO NP or BP powder was added to 25 mL of 10.0 g L –1 sodium citrate solution (pH 7.0), and the solution was sonicated and stirred for 4 h in a water bath (25 °C, 40 kHz, 50 W).…”

“…The particle coating method followed a previous study with minor modifications. 31 Briefly, 4.0 g of ZnO NP or BP powder was added to 25 mL of 10.0 g L −1 sodium citrate solution (pH 7.0), and the solution was sonicated and stirred for 4 h in a water bath (25 °C, 40 kHz, 50 W). The coated particles were then collected by centrifugation (5000g, 40 min) and washed with deionized water three times.…”

Toward achieving harmonization in a nanocytotoxicity assay measurement through an interlaboratory comparison study

“…have shown decreased agglomeration of NPs in media with proteins (Schulze et al, 2008;Sager et al, 2007;Tantra et al, 2010;Kwon et al, 2014), increased agglomeration from serum proteins has been observed in other studies (Murdock et al, 2008;Caracciolo et al, 2014). In the serum-containing media, the lower zeta potential reduced electrostatic stabilization while stabilization by steric repulsion depends on the protein corona which in turn depends on the protein loading on the surface, composition of the proteins in the serum, and the surface chemistry of the particles, which in this case was not sufficient to stabilize the NH 2 -PS NP.…”

Chitosan-Based Nano Systems for Natural Antioxidants in Breast Cancer Therapy

“…The stability of nanoparticles can be a common concern due to issues such as: (a) Agglomeration occurs when nanoparticles aggregate, leading to the loss of their unique properties and reduced stability [142]. Surface modification and the use of stabilizing agents can help to prevent agglomeration by creating repulsive forces between particles [143][144][145].…”