Fig. 1

Preparation and characterization of BPSP. a, b TEM and AFM images of BPNSs, respectively. c Particle size of BPNSs, BP@PEG, BPS, and BPSP. d, e TEM and AFM images of BPSP. f Zeta potentials of BPNSs, BP@PEG, BPS, and BPSP. g, h XPS of BPNSs and BPSP. i Raman spectra of bulk BP and exfoliated BPNSs and BPSP. j Ultraviolet/visible (UV/Vis) spectra of BPNSs at different concentrations (20, 30, 40, 50, 60, and 85 μg/mL). The inset shows the normalized absorbance intensity over the characteristic cell length (A/L) at different concentrations for λ = 1064 nm. k Photographs of (i) BPSP and (ii) BPNSs dispersed in water after 1, 3, 5, 7, and 9 days. l UV/Vis spectra of (i) BPSP and (ii) BPNSs with dispersion time in the water. m Drug loading capacity of BP@PEG. n In vitro release profile of free SF, BPS, BPSP, and BPSP + L. The data are shown as the mean ± SD (n = 3). **p < 0.01