Photodegradation enhances the toxic effect of anthracene on skin.

Anthracene, a polycyclic aromatic hydrocarbon (PAH), is a widespread environmental pollutant that poses potential risks to human health. Exposure to anthracene can result in various adverse health effects, including skin-related disorders. Photo exposure sufficiently removes the anthracene from the environment but also generates more degradation products which can be more toxic. The goal of this study was to assess the change in anthracene dermotoxicity caused by photodegradation and understand the mechanism of this change. In the present study, over 99.99% of anthracene was degraded within 24 h of sunlight exposure, while producing many intermediate products including 9,10-anthraquinone and phthalic acid. The anthracene products with different durations of photo exposure were applied to 2D and 3D human keratinocyte cultures. Although the non-degraded anthracene significantly delayed the cell migration, the cell viability and differentiation decreased dramatically in the presence of the photodegraded anthracene. Anthracene photodegradation products also altered the expression patterns of a number of inflammation-related genes in comparison to the control cells. Among these genes, il1a, il1b, il8, cxcl2, s100a9, and mmp1 were upregulated whereas the tlr4 and mmp3 were downregulated by the photodegraded anthracene. Topical deliveries of the photodegraded and non-degraded anthracene to the dorsal skin of hairless mice showed more toxic effects by the photodegraded anthracene. The 4-hour photodegradation products of anthracene thickened the epidermal layer, increased the dermal cellularity, and induced the upregulation of inflammatory markers, il1a, il1b, s100a9, and mmp1. In addition, it also prevented the production of a gap junction protein, Connexin-43. All the evidence suggested that photodegradation enhanced the toxicities of anthracene to the skin. The 4-hour photodegradation products of anthracene led to clinical signs similar to acute inflammatory skin diseases, such as atopic and contact dermatitis, eczema, and psoriasis. Therefore, the potential risk of skin irritation by anthracene should be also considered when an individual is exposed to PAHs, especially in environments with strong sunlight.

Materials, surfaces, and interfacial phenomena in nanoplastics toxicology research.

In response to the growing worldwide plastic pollution problem, the field of nanoplastics research is attempting to determine the risk of exposure to nanoparticles amidst their ever-increasing presence in the environment. Since little is known about the attributes of environmental nanoplastics (concentration, composition, morphology, and size) due to fundamental limitations in detection and quantification of smaller plastic particles, researchers often improvise by engineering nanoplastic particles with various surface modifications as models for laboratory toxicological testing. Polystyrene and other commercially available or easily synthesized polymer materials functionalized with surfactants or fluorophores are typically used for these studies. How surfactants, additives, fluorophores, the addition of surface functional groups for conjugation, or other changes to surface attributes alter toxicological profiles remains unclear. Additionally, the limited polymers used in laboratory models do not mimic the vast range of polymer types comprising environmental pollutants. Nanomaterials are tricky materials to investigate due to their high surface area, high surface energies, and their propensity to interact with molecules, proteins, and biological probes. These unique properties can often invalidate common laboratory assays. Extreme care must be taken to ensure that results are not artefactual. We have gathered zeta potential values for various polystyrene nanoparticles with different functionalization, in different solvents, from the reported literature. We also discuss the effects of surface engineering and solvent properties on interparticle interactions, agglomeration, particle-protein interactions, corona formation, nano-bio interfaces, and contemplate how these parameters might confound results. Various toxicological exemplars are critically reviewed, and the relevance and shortfalls of the most popular models used in nanoplastics toxicity studies published in the current literature are considered.

Impact of Polycyclic Aromatic Hydrocarbon Accumulation on Oyster Health.

In the past decade, the Deepwater Horizon oil spill triggered a spike in investigatory effort on the effects of crude oil chemicals, most notably polycyclic aromatic hydrocarbons (PAHs), on marine organisms and ecosystems. Oysters, susceptible to both waterborne and sediment-bound contaminants due to their filter-feeding and sessile nature, have become of great interest among scientists as both a bioindicator and model organism for research on environmental stressors. It has been shown in many parts of the world that PAHs readily bioaccumulate in the soft tissues of oysters. Subsequent experiments have highlighted the negative effects associated with exposure to PAHs including the upregulation of antioxidant and detoxifying gene transcripts and enzyme activities such as Superoxide dismutase, Cytochrome P450 enzymes, and Glutathione S-transferase, reduction in DNA integrity, increased infection prevalence, and reduced and abnormal larval growth. Much of these effects could be attributed to either oxidative damage, or a reallocation of energy away from critical biological processes such as reproduction and calcification toward health maintenance. Additional abiotic stressors including increased temperature, reduced salinity, and reduced pH may change how the oyster responds to environmental contaminants and may compound the negative effects of PAH exposure. The negative effects of acidification and longer-term salinity changes appear to add onto that of PAH toxicity, while shorter-term salinity changes may induce mechanisms that reduce PAH exposure. Elevated temperatures, on the other hand, cause such large physiological effects on their own that additional PAH exposure either fails to cause any significant effects or that the effects have little discernable pattern. In this review, the oyster is recognized as a model organism for the study of negative anthropogenic impacts on the environment, and the effects of various environmental stressors on the oyster model are compared, while synergistic effects of these stressors to PAH exposure are considered. Lastly, the understudied effects of PAH photo-toxicity on oysters reveals drastic increases to the toxicity of PAHs via photooxidation and the formation of quinones. The consequences of the interaction between local and global environmental stressors thus provide a glimpse into the differential response to anthropogenic impacts across regions of the world.

A microchip-based flow injection-amperometry system with mercaptopropionic acid modified electroless gold microelectrode for the selective determination of dopamine.

A novel chip-based flow injection analysis (FIA) system has been developed for automatic, rapid and selective determination of dopamine (DA) in the presence of ascorbic acid (AA). The system is composed of a polycarbonate (PC) microfluidic chip with an electrochemical detector (ED), a gravity pump, and an automatic sample loading and injection unit. The selectivity of the ED was improved by modification of the gold working microelectrode, which was fabricated on the PC chip by UV-directed electroless gold plating, with a self-assembled monolayer (SAM) of 3-mercaptopropionic acid (MPA). Postplating treatment methods for cleaning the surface of electroless gold microelectrodes were investigated to ensure the formation of high quality SAMs. The effects of detection potential, flow rate, and sampling volume on the performance of the chip-based FIA system were studied. Under optimum conditions, a detection limit of 74 nmol L(-1) for DA was achieved at the sample throughput rate of 180 h(-1). A RSD of 0.9% for peak heights was observed for 19 runs of a 100 micromol L(-1) DA solution. Interference-free determination of DA could be conducted if the concentration ratio of AA-DA was no more than 10.