Effects of humic acid and bovine serum albumin on the agglomeration and sedimentation of oxide nanoparticles

Abstract

Abstract:To better understand the nanoparticle (NP) transport in the environment, the agglomeration and sedimentation of Al 2 O 3 , SiO 2 , and TiO 2 NPs were evaluated after being treated with bovine serum albumin (BSA) and a commercial humic acid (HA). The morphology of NP agglomerates was examined through a transmission electron microscope (TEM), and the agglomeration kinetics was evaluated using established time-resolved dynamic light scattering techniques. BSA treatments decreased the hydrodynamic diameters (d H ) of the three NPs in both NaCl and CaCl 2 electrolytes due to their steric repulsive forces caused by the BSA globular architecture. The treatments using HA induced the smallest d H of NPs in NaCl electrolyte, but the largest d H of NPs was found in CaCl 2 electrolyte, because the HA bound to each other via calcium complexation and thereby enhanced the NP agglomeration. The zeta potentials of NPs were not the dominant factor to affect agglomeration. The NP sedimentation kinetics were studied through measuring the suspension optical absorbance. It was shown that the BSA treatments retarded the sedimentation in most situations; however, HA treatments accelerated the sedimentation greatly in CaCl 2 electrolyte, which was consistent with the measured changes in the d H values. The smallest d H of HA-treated NPs in NaCl electrolyte did not result in the lowest sedimentation rate, which indicated that the agglomeration size was not the only factor to affect the NP sedimentation.

Environmental risks of engineered nanomaterials

“…For example, BSA treatment was observed to enhance the colloidal stability of Al 2 O 3 , SiO 2 , and TiO 2 nanoparticles in Na + and Ca 2+ solutions, while DOM treatment decreased the stability greatly in Ca 2+ solution (Hu et al, 2014). Similar phenomenon was observed for the stablized C 60 suspension , i.e., DOM could enhance the colloidal stability in Na + solution but decrease the stability significantly in Ca 2+ and La 3+ solutions.…”

“…C 60 powders were also observed unable to be stably suspended in water or in DOM solution even with the assistance of sonication in dispersion . Moreover, the stably suspended nanoparticles may not remain stable in the presence of environmentally relevant cations (e.g., Na + , K + , Ca 2+ , Mg 2+ , and La 3+ ) (Hu et al, 2014;Yang et al, 2014;Zhang et al, 2014), especially once they were diluted (Yang et al, 2014). Dilution is a process commonly occurring once contaminants are released into the environment.…”

Mitigating effect of organic matter on the in vivo toxicity of metal oxide nanoparticles in the marine environment

“…This is due to the globular architecture of the adsorbed BSA which induces long range steric repulsive forces among NPs. 22,44,45 The sedimentation profiles recorded for the 200 μM NP suspensions ( Fig. 2C and D) highlight that NOM could not counteract the progressive sedimentation of either nanomaterial in the ASW medium.…”

A Review of Metal and Metal-Oxide Nanoparticle Coating Technologies to Inhibit Agglomeration and Increase Bioactivity for Agricultural Applications

“…It is not always practical to apply coatings during complex NP syntheses but breaking down agglomerates through sonication can provide new windows of opportunity for introducing coatings [36,46]. Even without preserving the initial size of NPs after synthesis, limiting agglomerate size can be important in alleviating toxicity and sedimentation [62][63][64]. Coatings can help tailor the NP surfaces for a variety of specific agricultural applications as long as care is taken to mediate the bioavailability of NPs with consideration for plant and environmental toxicity [12][13][14]64,65].…”