# Impact of Tylosin Tartrate and Ciprofloxacin on the Deposition of Negatively Charged Polystyrene Nanoparticles onto SiO2

## TL;DR

This study examines how two antibiotics affect the behavior of negatively charged nanoparticles in water, showing that their surface properties and interactions with antibiotics influence nanoparticle deposition.

## Contribution

The study reveals how tylosin and ciprofloxacin differentially impact nanoparticle aggregation and deposition based on surface chemistry and ionic strength.

## Key findings

- Tylosin induces aggregation of sulfate-terminated nanoparticles and increases their zeta potential at high ionic strengths.
- Ciprofloxacin has minimal impact on both nanoparticle types across ionic strength conditions.
- Tylosin prevents sulfate-terminated nanoparticle deposition, while ciprofloxacin enhances it.

## Abstract

Aqueous micropollutants
can enter the environment through the degradation
of macropollution and through ineffective wastewater treatment. Nanoparticles
(NPs) and antibiotics, two classes of micropollutants, are of particular
concern because of their increased reactivity and potential toxicological
effects. The high surface area-to-volume ratio of NPs makes them susceptible
to the sorption of other organic contaminants, including antibiotics.
The environmental transformations that NPs undergo complicate the
determination of where they and any adsorbed organic contaminants
may accumulate in the environment. This work aims to investigate the
role of surface termination in the environmental transformations and
deposition of polystyrene nanoparticles (PSNPs) in varying ionic strength
and antibiotic matrices. We used two negatively charged PSNP model
systems, carboxyl (COOH-PSNPs)- and sulfate (SO4-PSNPs)-terminated
PSNPs, and two different antibiotic model systems, tylosin (TYL) tartrate
and ciprofloxacin (CIP). Increasing the concentration ratio of TYL
to PSNPs impacted the hydrodynamic and electrokinetic properties of
the PSNPs in surface termination-, ionic strength-, and concentration-dependent
manners. High concentrations of TYL induced aggregation of the SO4-PSNPs and resulted in an increased ζ potential at high
ionic strengths for both particle types, whereas CIP had minimal impacts
on both types of particles across ionic strength conditions. Using
a quartz crystal microbalance to investigate the deposition of both
pristine and transformed PSNPs onto a model sediment surface, SiO2, we observed more deposition of SO4-PSNPs than
of COOH-PSNPs at high ionic strengths. The presence of TYL eliminated
attachment of the SO4-PSNPs and had a negligible impact
on the deposition of COOH-PSNPs, whereas CIP increased attachment
of the SO4-PSNPs and had a negligible impact on the deposition
of the COOH-PSNPs. Together, these results highlight the importance
of surface termination and micropollutant physicochemical properties
in understanding environmental transformations that NPs may undergo
and the subsequent environmental consequences they may have.