Multi stimuli-responsive drug delivery systems obtained by green chemistries

Ihe development of multi-stimuli-responsive hydrogels has garnered significant attention among scientists working on the engineering of active formulations, owing to the ability to tune and control their features in response to stimuli coming from the surrounding environment (e.g., temperature, pH, UV/Vis light). For example, thermo-responsive hydrogels exhibit temperaturecontrolled viscosity changes and sol-to-gel transition; pH-sensitive formulations display increased or decreased capability to absorb fluids as a function of their pH value; UV/Vis light-sensitive formulations demonstrate tunable network strength based on light intensity and exposure time. Regardless of the specific external stimulus, imparting such responsiveness often necessitates the engineering of very complex formulations and/or the functionalization of their polymeric components through chemistries requiring the use of organic solvents and highly toxic reagents. In this work, we explored the potential to confer multi-stimuli-responsiveness to amphiphilic poly(ether urethane)s(PEUs), differing for their building block composition, by employing various environmentally friendly approaches, finally leading to polymers with suitable features for their exploitation as smart drug delivery (SDD) systems and biomaterial inks.