Nano 90

The measurements of drug loading efficiency (DLE) and drug loading capacity (DLC) of nanogels were based on the fluorescence intensity using the standard curve of DOX in water (Ex/Em max of 498/593 nm, R² = 0.997). According to the fluorescence spectra, both DOX and DOX-loaded nanogels share identical fluorescence spectra with the same Ex/Em max (Figure 1E). Following measurement of its fluorescence intensity, DOX-loaded nanogels were dispersed in DI water and diluted to a final concentration of 10.0 µg/mL. DLE and DLC were then calculated using the following equations: $$\mathrm{DLE} (\%)=\frac{actual loaded DOX}{Initial feed of DOX} \times 100$$
$$\mathrm{DLC} (\%)=\frac{actual loaded DOX}{DOX-loaded nanogel} \times 100$$
The Z-average hydrodynamic diameter (d_H) and polydispersity index (PdI) of DOX-loaded nanogels (1.0 mg/mL) in 1 mM KCl solution or PBS (pH 7.4) were determined using a dynamic light scattering (DLS, Malvern, Zetasizer Nano 90S) system equipped with a 4 mV He–Ne ion laser (λ = 633 nm) as the light source at a scattering angle of 90°. All samples were diluted from stock (10 mg/mL, prepared with sonication at 40% amplitude for 30 s) to the desired media concentration (1.0 mg/mL) without additional sonication. The ζ potentials of bare nanogels and DOX-loaded nanogels were measured using electrophoretic light scattering (ELS) measurements (Malvern, Zetasizer Nano ZC) in 1 mM KCl solution.