Comparative profiling and exposure assessment of microplastics in differently sized Manila clams from South Korea by µFTIR and Nile Red staining.

The accumulation of microplastics in marine organisms is an emerging concern. Due to trophic transfer, the safety of seafood is under investigation in view of the potential negative effects of microplastics on human health. In this study, market samples of Manila clams (Ruditapes philippinarum) from South Korea were segregated into two groups of considerably different size (p < 0.05), namely small clams with shell length of 40.69 ± 3.97 mm, and large clams of shell length 51.19 ± 2.86 mm. Comparative profiling of the number, size, shape, and polymer type of microplastics were performed using µFTIR imaging and Nile red staining. Overall, µFTIR detected only 1559 microplastics while 1996 microplastics were counted based on staining from 61 Manila clams (30 small and 31 large), leading to an overestimation of 18 to 75 %. Comparable microplastics concentration, based on µFTIR, were observed at 2.70 ± 1.66 MP/g or 15.64 ± 9.25 MP/individual for the small samples, and 3.65 ± 1.59 MP/g or 41.63 ± 16.90 MP/individual for the large ones (p > 0.05). Particle diameters of 20-100 µm was the most dominant, accounting for 44.6 % and 46.5 % of all microplastics from the small and large groups, respectively. Particles, with a circularity (resemblance to a circle) value between 0.6 and 1.0, were the most prevalent, followed by fragments and fibers. At least 50 % of microplastics from the small and large samples were polystyrene, making it the most abundant polymer type. Despite the substantial difference in the size of the animals, only a weak to moderate correlation was observed between microplastics content and the physical attributes of the clams such as shell length and weight, (soft) tissue weight, and total weight (Spearman's coefficient < 0.5). The estimated intake of microplastics by the Korean population was 1232 MP/person/year via small clams, 1663 MP/person/year via large clams, and 1489 MP/person/year via clams independent of size.

Quantitative assessment of nanoparticle surface hydrophobicity and its influence on pulmonary biocompatibility.

To date, the role of nanoparticle surface hydrophobicity has not been investigated quantitatively in relation to pulmonary biocompatibility. A panel of nanoparticles spanning three different biomaterial types, pegylated lipid nanocapsules, polyvinyl acetate (PVAc) and polystyrene nanoparticles, were characterized for size, surface charge, and stability in biofluids. Surface hydrophobicity of five nanoparticles (50-150nm) was quantified using hydrophobic interaction chromatography (HIC) and classified using a purpose-developed hydrophobicity scale: the HIC index, range from 0.00 (hydrophilic) to 1.00 (hydrophobic). This enabled the relationship between the nanomaterial HIC index value and acute lung inflammation after pulmonary administration to mice to be investigated. The nanomaterials with low HIC index values (between 0.50 and 0.64) elicited little or no inflammation at low (22cm(2)) or high (220cm(2)) nanoparticle surface area doses per animal, whereas equivalent surface area doses of the two nanoparticles with high HIC index values (0.88-0.96) induced neutrophil infiltration, elevation of pro-inflammatory cytokines and adverse histopathology findings. In summary, a HIC index is reported that provides a versatile, discriminatory, and widely available measure of nanoparticle surface hydrophobicity. The avoidance of high (HIC index>~0.8) surface hydrophobicity appears to be important for the design of safe nanomedicines for inhalation therapy.