Ecotoxicity of a potential drug nano-formulation: PAMAM-dendrimer and minocycline

The varied composition, size, and shape of nanomaterials (1-100 nm size range) offer numerous exciting possibilities for the development of new industrial, biomedical, electronic products and have the potential to stimulate the global economy.1 On the darker side, the marked research efforts presently deployed to develop novel applications with nanomaterials will eventually lead to some releases in the aquatic environment likely via urban industrial/municipal point sources of pollution. This is clearly cause for concern as recent studies suggest that adverse health2,3 and environmental4,5 effects are linked to nanoproduct pollutants. In the biomedical field, drug delivery systems combining nano-dendrimers (as a platform for delivery) and specific guest molecules (e.g. pharmaceuticals) are being investigated for efficient treatment of diseases (e.g., cancer, inflammation, cardiac and microbial problems).6 While characteristics (molecular size, shape, dimension, density, polarity, flexibility, solubility, drug carrying capacity, etc.) of dendrimers will vary based on their construction,7 cationic dendrimers are among the most common candidates in terms of pharmaceutical development and they are being considered for the drug delivery of anti-microbials such as minocycline.8 In this study, we investigated the ecotoxicity of three PAMAM dendrimers (artificial macromolecules with tree-like structures, described in the methods section, and of minocycline, individually and in combination by conducting toxicity tests with microorganisms representing different levels of biological organization. Our objectives are to obtain preliminary information on the potential hazard of PAMAM dendrimers and minocycline. Materials and Methods