F200s fei

Dynamic lighting scattering (DLS) was used to determine the size and zeta potential of the HmA@Ava particles using a Zetasizer Nano ZS instrument (Malvern, UK). Fourier transform infrared spectrometry (FTIR, Bruker TENSOR II) and UV–vis (Perkin-Elmer, Lambda 25, USA) were used to study the encapsulation of Ava into HmA. A field emission scanning electron microscope (FESEM, SU8010 HITACHI) and transmission electron microscope (TEM, Talos F200S FEI) were used to observe the morphology of HmA@Ava particles.

DOX was packed into HmA NPs via the following procedure: Briefly, Zn (NO₃)₂ (94 μL, 0.1 M) was added to 1 mL of HEPES buffer solution (pH 8.0) containing 4 mg of DOX, 3.9 mg of His₆, and 5.0 mg of PVP. The packaging procedure was ultrasonicated at 4 °C for 10 min, and the NPs were collected by centrifugation (14000 rpm, 15 min). Finally, the pellet was washed three times with deionized water, redispersed by ultrasonication, and stored in 1 mL of water at 4 °C before testing (stock solution).
Diluting 100 μL of stock solution into 1 mL of water, the particle size, dispersity coefficient PDI, and surface zeta potential of the NPs (HmA and HmA@DOX) were examined using a Zeta-sizer Nano ZS instrument (Malvern, UK). For the scanning electron microscopy (FE-SEM, Hitachi, SU8010) test, the 5 μL NPs were dropped onto a silicon wafer, fully dried, then gold sprayed. The 2-μL, 100-times diluted stock solution was dropped onto the copper grid coated with carbon film and observed by field emission transmission electron microscopy (TEM, Talos F200S FEI) after it had completely dried. After the DOX and NPs were diluted, the absorbance of the samples was measured using an ultraviolet spectrophotometer.