For instance, polyamidoamine (PAMAM) nanocarriers demonstrated effective encapsulation of indoximod (an immune checkpoint inhibitor) and Dox, achieving loading contents of 6 and 12%, respectively. While the former was physically encapsulated, Dox was covalently linked to the polymer backbone through a hydrazone bond, which additionally conferred pH responsiveness. Their incorporation into a PCLA-b-PEG-b-PCLA copolymer hydrogel resulted in a viscous formulation that transitioned to a solid state at body temperature, enabling sustained cumulative release for a duration of up to 24 days. Removal of water is an easy method for rising the concentration of NP dispersions that allows for a higher content to be loaded into hydrogels. As an example, using simple Millipore Amicon Ultra centrifugation tubes, drug-loaded PLA-b-PEG NPs reached final concentration as high as 150 mg mL -1 , and they could then successfully be incorporated into HPMC-based hydrogels ensuring sustained drug release over a month.