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Plastics of different sizes (micro- and nano-sized) are often identified in aquatic environments. Nevertheless, their influence on marine organisms has not been widely investigated. In this study, the responses of the microalga Chlorella vulgaris to micro- and nanoplastics exposure were examined using long term toxicity test. The plastics tested were carboxyl-functionalized and non-functionalized polystyrene of 20, 50 and 500 nm in diameter. A reduction in algal cell viability and chlorophyll a concentration has been observed after exposure to the small sizes (20 and 50 nm) of plastics. Lactate dehydrogenase activity and reactive oxygen species concentration/production were significantly higher after exposure to the 20 nm nanoplastics than that of control confirming the stress condition. Fourier transform infrared (FTIR) spectroscopy analysis proved the attachment of nanoplastics to microalgae and rearrangement of extracellular polymeric substances. The cellular stress appeared as increased cell size, deformed cell wall and increased volume of starch grains.

Many neurodegenerative diseases, cancer, and infections of the brain become more prevalent as populations become older. Despite major advances in neuroscience, the blood–brain barrier (BBB) ensures that many potential therapeutics cannot reach the central nervous system (CNS). The BBB is formed by the complex tight junctions between the endothelial cells of the brain capillaries and their low endocytic activity. It results in the capillary wall that behaves as a continuous lipid bilayer and prevents the passage of polar substances. Drug delivery to the brain has remained one of the most vexing problems in translational neuroscience research, because of the difficulties posed by the BBB. Several strategies for delivering drugs to the CNS have been developed. This review rationalizes the strategies to target drugs to the brain by using different colloids.