Smart block copolymers for biomedical applications

Smart polymers are polymers that respond with rapid changes to external stimuli such as pH, temperature, light or ionic strength. Responses to the stimuli may manifest themselves as changes in solubility, shape or surface characteristics. These materials are very intersesting for different biomedical applications such as drug delivery systems, tissue engineering or sensors. In this work, we focused on two separate systems: on the one hand, micelles and, on the other hand, iron oxide nanoparticles. These nanoparticles are generally synthesized in a one-step process by alkaline coprecipitation of iron (II) and iron (III) precursors. However, iron oxide nanoparticles are not stable enough in physiological conditions to be used as is. A stabiliser coating is needed to avoid aggregation and precipitation of the colloids in body fluids. For this coating, the polymer blocks chosen are PEO (to confer stealthiness), PAA (pH-responsive) and PNIPAM (thermoresponsive). This triblock copolymer was synthesized by RAFT polymerization and was used alone to form micelles and with iron oxide to make magnetic stabilized nanoparticles. The behaviour of micelles and coated nanoparticles was investigated by a combination of DLS, TEM and zeta potential measurements. To highlight the potentiality of these nanomaterials, their cytotoxicity will be studied and compared