*2.1. Characterization of Glutathione Responsive* β*-cyclodextrin-Based Nanosponges*

GSH-NSs have a size of about 200 nm and a negative surface charge, in agreement with our previous papers [35,37,38]. Table 1 reports the average diameters, polydispersity indices, and zeta potentials of blank and 6-coumarin loaded GSH-NS type B and D. The different content of disulfide bridges in the two type of GSH-NS (B and D) did not affect their physico-chemical characteristics. Fluorescent labeling did not significantly alter the values of these parameters. Transmission electron microscopy (TEM) analysis of GSH-NS shows the spherical shape and smooth surfaces of the nanosponges.

**Table 1.** The physico-chemical characteristics of glutathione-responsive β-cyclodextrin-based nanosponge (GSH-NS) formulations.

