2 research outputs found
Fate of Nanoplastics in Marine Larvae: A Case Study Using Barnacles, Amphibalanus amphitrite
The exposure of nanoplastics
was investigated by observing their
interaction with Amphibalanus amphitrite (commonly known as acorn barnacles). Poly(methyl methacrylate) (PMMA)
and fluorescent perylene tetraester (PTE) dye were used to prepare
highly fluorescent nanoplastic particles. At concentrations of 25
ppm, the PMMA particles showed no detrimental impact on barnacle larvae
and their microalgae feed, Tetraselmis suecica and Chaetoceros muelleri. PMMA nanoplastics
were ingested and translocated inside the body of the barnacle nauplii
within the first 3 h of incubation. The fluorescent PMMA particles
inside the transparent nauplius were tracked using confocal fluorescence
microscopy. Subsequently, the nanoplastics were fed to the barnacle
nauplii under two conditionsacute and chronic exposure. The
results from acute exposure show that nanoplastics persist in the
body throughout stages of growth and developmentfrom nauplius
to cyprid and juvenile barnacle. Some egestion of nanoplastics was
observed through moulting and fecal excrement. In comparison, chronic
exposure demonstrates bioaccumulation of the nanoplastics even at
low concentrations of the plastics. The impacts of our study using
PMMA nanoparticles exceeds current knowledge, where most studies stop
at uptake and ingestion. Here we demonstrate that uptake of nanoparticles
during planktonic larval stages may persist to the adult stages, indicating
potential for the long-term impacts of nanoplastics on sessile invertebrate
communities
Polyion Multilayers with Precise Surface Charge Control for Antifouling
We report on a molecular fabrication
approach to precisely control surface ζ potentials of polymeric
thin layers constructed by electrostatic layer-by-layer (LbL) assembly
methods. The protocol established allows us to achieve surface isoelectric
points (IEP) in the pH range of 6–10. Poly(acrylic acid) (PAA,
a weak polyanion) and poly(diallyldimethylammonium chloride) (PDADMAC,
a strong polycation) were chosen to build up the bulk films. The weak
polycation polyethylenimine (PEI) was applied as a top layer. A unique
feature of this approach is that the chemical composition of the top
layer is not affected by the manipulation of the ζ potential
of the films. Surface charge tuning is achieved by controlling the
degree of ionization of the weak polyelectrolytes at various pH values
and subsequent manipulation of the amount of polyelectrolyte deposited
in the penultimate and last layers, respectively. Following assembly
and characterization, the films were used as candidates for antifouling
surfaces. The fouling behavior of barnacle cyprids and bacteria on
the LbL films with similar hydrophilicity and roughness but different
surface charge densities were studied. We found that more cyprids
of Amphibalanus amphitrite settled
on the negatively charged LbL film compared to the neutral or positively
charged LbL film. In bacterial adhesion tests employing Pseudomonas, Escherichia coli, and Staphylococcus aureus, more
bacteria were observed on the positively charged LbL film compared
with the neutral and negatively charged LbL films, possibly as a result
of the negative potential of the bacterial cell wall. The procedures
proposed allow one to adjust surface isoelectric points of LbL architectures
to achieve optimal antifouling performance of a given material taking
into account specific pH values of the environment and the character
of the fouler