Rf 6000 spectrophotometer

A PerkinElmer Lambda 1050 UV-250 UV/vis/NIR
spectrophotometer was used for the UV–vis absorption measurements
of the PGQDs. The fluorescence spectra and photostability measurements
were acquired by a Shimadzu RF-6000 spectrophotometer. A Malvern model
of Nano-ZS Zetasizer was used to measure size distribution of the
PGQDs as well as the zeta potential at various pHs. A Thermo Fisher
Scientific Nicolet iS5 Fourier transform infrared spectrometer (FT-IR)
was utilized to obtain the IR spectra of PGQDs, TCPP, CBDA-2, and
the GQDs. A Hitachi 7500 Transmission Electron Microscope (TEM) and
a JEOL JEM-F200 High-Resolution Transmission Electron Microscope (HRTEM)
were used for particle imaging. Powder X-ray diffraction (XRD) measurement
was conducted on a Rigaku SmartLab X-ray diffractometer at a scan
rate of 4°/min with Cu Kα irradiation (λ = 0.15418)
at an accelerating voltage of 40 kV and a tube current of 44 mA. The
fine powder sample was loaded on a zero-background silicon wafer sample
holder. An Olympus FV1000 MPE Basic Multiphoton Microscope was used
for in vitro confocal imaging. HeLa cells were cultured
overnight with gradient concentrations of the PGQDs for in
vitro imaging and cytotoxicity analysis. A ELX800 plate reader
was used for the cell viability experiments using the protocol of
CytoTox 96 Non-Radioactive Cytotoxicity Assay kit.