F 7100

Coloured microspheres were recovered from transmural myocardial samples taken from the central area at risk by digestion with 4 mol L⁻¹ KOH and subsequent filtration (8 µm pore size, Pieper Filter, Bad Zwischenahn, Germany). Fluorescent dye was resolved from microspheres and quantified in a spectrophotometer (F-7100, Hitachi High-Tech, Krefeld, Germany). Blood flow was calculated as blood flow per tissue mass.

The fluorescence spectra of the RPH-SIFs were investigated using a fluorophotometer (F7100, Hitachi, Ltd., Tokyo, Japan). The final concentration of RPH was 1 mg/mL, and the concentration of encapsulated SIF was 0–60 μmol/L. RPH-SIF nanoparticles were determined by scanning emission wavelengths from 300 to 450 nm, with an excitation wavelength of 290 nm at 298, 304 and 310 K, to obtain the fluorescence spectra of the RPH-SIF nanoparticles. The excitation and emission slit widths were 5.0 nm.
The fluorescence quenching parameters were calculated from the following equations: $$\frac{{\mathrm{F}}_0}{\mathrm{F}}=1+{\mathrm{K}}_{\mathrm{s}\mathrm{v}}\left[\mathrm{Q}\right]$$
$$\log \left(\frac{{\mathrm{F}}_0-\mathrm{F}}{\mathrm{F}}\right)=\mathrm{l}\mathrm{o}\mathrm{g}{\mathrm{K}}_{\mathrm{A}}-\mathrm{n}\mathrm{l}\mathrm{o}\mathrm{g}\left[\mathrm{Q}\right]$$
In Equation (3), F₀ and F represent the fluorescence intensities of proteins in the absence and presence of SIF. K_sv represents the Stern–Volmer quenching constant, and [Q] represents the concentration of SIF. In Equation (4), K_A and n denote the binding constant and number of binding sites, respectively.
Equations (5) and (6) were used to calculate the thermodynamic parameters to determine the main driving force: $$\mathrm{l}\mathrm{n}{\mathrm{K}}_{\mathrm{A}}=-\frac{∆\mathrm{H}}{\mathrm{R}\mathrm{T}}+\frac{∆\mathrm{S}}{\mathrm{R}}$$
$$∆\mathrm{G}=∆\mathrm{H}-\mathrm{T}∆\mathrm{S}$$
where ΔH and ΔS represent the enthalpy and entropy changes, respectively. R represents the gas constant (8.314 J·mol⁻¹ K⁻¹). T represents the thermodynamic temperature, and ΔG represents the change in Gibbs free energy.

The GQDs were synthesized based on previous reports, with some modifications (34 (link)). Briefly, concentrated H₂SO₄ (60 ml) and HNO₃ (20 ml) were mixed with 0.3 g of carbon nanofibers. The mixture was ultrasonically stirred for 2 h and further stirred at 100°C for 24 h and the GQDs generated. After cooling, the solution containing the GQDs was diluted with 600 ml Milli-Q water. Sodium carbonate was used to adjust the pH to 8. The GQDs were further purified by dialysis with a molecular weight cutoff of 2,000 Da. The particle sizes of the GQDs were characterized using transmission electron microscopy (Hitachi HT7800, Tokyo, Japan). The fluorescence spectra of the GQDs were recorded using a fluorescence spectrophotometer (Hitachi F-7100, Tokyo, Japan).

¹H and ¹³C nuclear magnetic resonance (NMR) spectra were measured with a JOEL NMR spectrometer (JNM-ECZ400S, 400 MHz, Japan). The chemical shift was relative to tetramethylsilane (TMS) as the internal standard. Elemental analysis was tested by a Vario EL Cube. Steady-state and delayed photoluminescence spectra were collected using Hitachi F-7100. The photoluminescence lifetimes and time-resolved emission spectra were collected on an Edinburgh FLS1000 fluorescence spectrophotometer equipped with a xenon arc lamp (Xe900), a nanosecond hydrogen flash-lamp (nF920), and a microsecond flash-lamp (μF900), respectively. Photoluminescence efficiency was obtained on a Hamamatsu Absolute PL Quantum Yield Spectrometer C11347. Powder X-ray diffraction (PXRD) patterns were collected on a Smartlab (3 kW) X-ray diffractometer of a Japanese brand. The radioluminescence (RL) spectra were collected on an Edinburgh FS5 fluorescence spectrophotometer with an X-ray tube (Tungsten target, Moxtex). Photographs were taken with a Cannon EOS 90D camera. Unless other noted, all photophysical properties of the solids were collected at 298 K with relative humidity (RH) of ≈30% in air.

Nuclear magnetic resonance (¹H NMR and ¹³C NMR) spectra were obtained on a Bruker Ultra Shield Plus 400 MHz spectrometer. Deuterium dimethyl sulfoxide was as a solvent and the chemical shift was calibrated using tetramethylsilane (TMS) as the internal standard. Resonance patterns were recorded with the notation s (singlet), d (double), t (triplet), q (quartet), and m (multiplet). High-performance liquid chromatography (HPLC) was performed using a SunFireTM C18 column conjugated to an ACQUITY UPLCH-class water HPLC system. Steady-state photoluminescence, phosphorescence, and excitation time-dependent phosphorescence emission spectra were measured using Hitachi F7100. The lifetime decay curves under different light fluxes and pulse numbers were obtained on an Edinburgh FLSP1000 fluorescence spectrophotometer equipped with a nanosecond hydrogen flash-lamp (nF920) and a microsecond flash-lamp (μF900), respectively. The luminescent photos were taken by a Cannon EOS 700D camera under the irradiation of a hand-held UV lamp (365 nm). X-ray crystallography was achieved using a Bruker SMART APEX-II CCD diffractometer with graphite monochromated Mo-Kα radiation.