Hydrogelsand metallo-hydrogels: characterization,and their environmental and pharmaceutical applications

Abstract

The versatility on the applications of hydrogel materials make them veryattractive as adsorbents than can be used for decontamination of pollutants as well for drug-delivery. Adsorption is an efficient option for decontamination of heavy metal ions purposes due to their high loading capacity at the same time that particularly some of the obtained metallo-hydrogel (Cu(II)- and Co(II)-hydrogels) have catalytic activity on free radicals production from O2 and H2O2 . Also, hydrophilic hydrogels can respond to physiological stimuli such as pH, ionic strength and temperature for the correct delivery of the substance in the target site. For that reason, the synthesis of novel and smart hydrogels is required in order to satisfy the demand from the pharmaceutical and environmental sectors in the last decade. In addition, an exhaustive chemical and structural characterization is required in order to get the connectivity between the different atoms thorough the entire polymer network as well their acid-base properties. In this sense, we will summarize some of the most important methods used to characterize in different aspects these non-solublesystems as solid-state Nuclear Magnetic Resonance (ss-NMR), Infrared (IR) and Raman spectroscopies, potentiometric titrations, Dynamic Light Scattering (DLS), Small Angle Scattering (SAS), among others. Finally, we will discuss the applications of these materials for the removal of heavy metal ions and organic pollutants, in terms of efficiency in the uptake of these ions and the different techniques commonly used to study the generation of reactive oxygen species (ROS) from hydrogen peroxide (H2O2). Moreover, the new insights on the pharmaceutical applications of hydrogels will be focused on drug-delivery, contact lenses, biosensors and stimuli-responsive systems.