Auriga fib sem

TEM images were obtained with an FEI Titan Themis 200 TEM at an acceleration voltage of 200 kV. SEM images were obtained a Zeiss Auriga FIB-SEM. UV–vis–NIR absorption spectra were performed with a Shimadzu UV-3600 spectrophotometer. Using Beer’s law (A/L = αC), the AuNFs’ extinction coefficient was extracted from the slope of a plot of A/L versus concentration (C). The optical extinction per cell length (A/L) was determined from the optical extinction intensity at 1064 nm. The size, polydispersity index, and zeta potential of nanoparticles were determined by dynamic light scattering (Zetasizer 3000HS; Malvern Instruments, Worcestershire, UK). FTIR spectra were recorded in a range of 400–4000 cm⁻¹ at a 0.5–4 cm⁻¹ resolution with a Bruker Vertex 80v vacuum FTIR spectrometer. A 1064 nm multimode pump laser (Shanghai Connect Fiber Optics Co. Ltd.) was used as the irradiation source for NIR-II photothermal effect. For in vitro PAT, HA-4-ATP-AuNFs at different concentrations (0, 0.1, 0.2, 0.4, 0.8, and 1 mg mL⁻¹) were added into 200 μL tubes for PA signal detection using a PA instrument (VisualSonics Vevo 2100 LAZR systems) with an excitation wavelength of 1200 nm.