Sequestration of antibiotic by magnetic nanoparticles and potential application for water remediation

Tons of antibiotics are produced annually worldwide for consumption by humans or use in the treatment of animals, including fish. The release and presence of antibiotics in the environment is a hot topic, which was firstly highlighted in the US in the 70's and almost a decade later in England. Yet, it was in the mid-90s, with the progress of analytical techniques, that the knowledge about environmental contamination caused by these compounds excelled considerably. Most of these antibiotics are synthesized in order to remain stable in the environment for long periods, in such way their curative effect is guaranteed in time. Paradoxically, the same characteristics are responsible for their toxicity by bioaccumulation in aquatic and terrestrial ecosystems. Some antibiotics are systematically used in farms for animal care and prophylaxis of diseases. These compounds are released later in the environment through the feces and urine and can therefore easily reach waterways. Recent studies have shown concentrations of different types of antibiotics in wastewater, surface waters, seawater, groundwater and drinking water. The scientific community clearly states that the presence of pharmaceutical products cause adverse effects not only to aquatic ecosystems but also to human health. Especially antibiotics and antiparasitic drugs are abundantly used for veterinary purposes. Sulfonamides, fluoroquinolones, tetracyclines are frequently found in surface water at concentrations in the mg-ng L-1 range. Some of these compounds are quickly degraded, while others (such as oxytetracycline) persist and remain active in the environment for long periods. Better, and more effective, administration techniques of these molecules as well as the development of bioremediation techniques are thus considered of primary importance. At this regard, nanomaterials are looked with great interest since they have been developed for technical applications due to their extremely small size (1 to 100 nm), which supposes much larger surface to volume ratio compared with conventional particles and provides them with unique physical and chemical properties.