1 research outputs found
Natural Organic Matter Concentration Impacts the Interaction of Functionalized Diamond Nanoparticles with Model and Actual Bacterial Membranes
Changes to nanoparticle surface charge,
colloidal stability, and
hydrodynamic properties induced by interaction with natural organic
matter (NOM) warrant consideration in assessing the potential for
these materials to adversely impact organisms in the environment.
Here, we show that acquisition of a coating, or “corona”,
of NOM alters the hydrodynamic and electrokinetic properties of diamond
nanoparticles (DNPs) functionalized with the polycation poly(allylamine
HCl) in a manner that depends on the NOM-to-DNP concentration ratio.
The NOM-induced changes to DNP properties alter subsequent interactions
with model biological membranes and the Gram-negative bacterium <i>Shewanella oneidensis</i> MR-1. Suwannee River NOM induces changes
to DNP hydrodynamic diameter and apparent ζ-potential in a concentration-dependent
manner. At low NOM-to-DNP ratios, DNPs aggregate to a limited extent
but retain a positive ζ-potential apparently due to nonuniform
adsorption of NOM molecules leading to attractive electrostatic interactions
between oppositely charged regions on adjacent DNP surfaces. Diamond
nanoparticles at low NOM-to-DNP ratios attach to model membranes to
a larger extent than in the absence of NOM (including those incorporating
lipopolysaccharide, a major bacterial outer membrane component) and
induce a comparable degree of membrane damage and toxicity to <i>S. oneidensis</i>. At higher NOM-to-DNP ratios, DNP charge is
reversed, and DNP aggregates remain stable in suspension. This charge
reversal eliminates DNP attachment to model membranes containing the
highest LPS contents studied due to electrostatic repulsion and abolishes
membrane damage to <i>S. oneidensis</i>. Our results demonstrate
that the effects of NOM coronas on nanoparticle properties and interactions
with biological surfaces can depend on the relative amounts of NOM
and nanoparticles