*4.2. Preparation of Glutathione Responsive* β*-cyclodextrin-Based Nanosponge Nanosuspension*

GSH-NS nanosuspensions were prepared following the preparation protocol previously reported [35,38]. A weighed amount of GSH-NSs was suspended in a saline solution (NaCl 0.9%) at a concentration of 10 mg/mL. The suspension was homogenized by a high shear homogenizer (Ultraturrax®, IKA, Konigswinter, Germany) for 5 min at 24,000 rpm. The sample was then homogenized on a high-pressure homogenizer (EmulsiFlex C5, Avastin, Mannheim, Germany) for 90 min at a back pressure of 500 bar to further reduce the size of the nanosponges. The aqueous nanosponge nanosuspension was subsequently purified by dialysis (membrane cutoff 12,000 Da) to eliminate potential synthesis residues. The nanosuspension was stored at +4 ◦C and used for all experiments.
