Malavika Manju Sudheer

The accumulation of nanoplastics (NPs) in the environment poses serious ecological and health risks, underscoring the urgent need for simple and reliable detection methods. In this study, we explored the use of electrolyte-gated field-effect transistor (EG-FET) based sensors incorporating carbon nanotube (CNT) semiconducting channels (EG-CNTFET) for NPs detection. In particular, we first evaluated the EG-CNTFET’s sensitivity to two NPs models: non-functionalized polystyrene (PS), and polyethylene terephthalate (PET). EG-CNTFETs exhibited distinct responses to the two polymers: PS NPs induced a current increase of up to 35.48% at 0.25 mg/mL, whereas PET NPs caused a pronounced current decrease of up to 87.77% at the same concentration. Further tests with PS NPs types (with or without surface carboxylation) at low concentrations (ranging from 0.025 to 0.5 mg/mL) revealed high sensitivity, quantified as 26.4 μA*mL/mg for non-functionalized PS NPs and 20.5 μA*mL/mg for carboxylated PS NPs. Control experiments with pure electrolyte confirmed that the observed signal changes were not due to volumetric effects. These findings demonstrate the potential of EG-CNTFET-based sensors for sensitive detection of PS NPs, while highlighting the need for further investigation into their applicability for PET NPs detection.

The increasing production and accumulation of plastic waste, coupled with insufficient recycling practices, contribute to the growing presence of plastic in the environment. Nanoplastic particles are of particular concern, as they pose greater (health and environmental) risks and exhibit wider dispersion compared to macroplastics. The blood–brain barrier may be exposed to nanoplastics present in the blood, which could affect its functionality or even pass through and damage the central nervous system. This study examined the effects of polystyrene (PS) nanoparticles with different chemical surface modifications (pristine, carboxylated, aminated) and sizes (50 nm and 100 nm) on cells of the neurovascular unit (NVU): human brain endothelial cells, astrocytes, and pericytes. Results indicated that only high concentrations of nanoparticles (100 μg/mL and 300 μg/mL) applied for 48 h decreased cell viability and barrier integrity significantly. Specifically, 50 nm carboxylated PS particles reduced barrier integrity and altered tight junction gene expression substantially. Fluorescent labelling of the investigated particles enabled to confirm their uptake by all tested cell types of the NVU, but also highlighted that the labelling changes the particles’ properties. Furthermore, cell culture medium-dependent particle agglomeration and increase of size were inversely correlated with cellular internalisation, which has to be considered for future risk assessments.

Due to the well-documented negative environmental impacts of conventional plastics, the use of bioplastics has been increasing. Poly(lactic acid) (PLA) is currently among the most common and industrially available bioplastics. Although PLA is compostable under industrial conditions and generally degrades more quickly than conventional plastics, its breakdown in typical environmental settings remains problematic. PLA’s potential to contribute to plastic pollution through the release of microplastics and nanoplastics makes it crucial to understand how these particles behave, especially in marine environments. However, as for all nanoplastics, identifying, isolating, and quantifying PLA nanoplastics in water presents significant challenges. This study proposes a versatile approach to fabricate PLA nanoplastics through laser ablation in a water environment to mimic realworld samples. Commencing with bulk PLA films, this top-down method yields the formation of nanoplastics with an average diameter of 54.7 ± 26.7 nm. Surface and chemical analyses confirm the presence of carboxylic groups on their surface, potentially resembling the environmental degradation pathway of PLA under exposure to sunlight and humid environments. This indicates that the proposed process results in a PLA nanoplastics system that serves as an invaluable reference model, enabling realistic environmental scenario explorations and simulations for risk assessment evaluations on bio-based nanoplastics.