Uv 2550 uv vis spectrometer

The incorporation process of the doxorubicin drug was performed by preparing a DOX solution with a concentration of 0.75 mg.mL⁻¹. Subsequently, 25 mg of MSN/HA-Eu(2%)-Gd(1%) nanocomposite and MSN/HA-Eu(2%)-Gd(1%)/P(MAA) luminescent hybrid system were added to this solution at room temperature, and remained under constant stirring for 72 h. The suspension was filtered, and the sample washed (with water and ethanol) and dried for 24 h. The drug concentration was measured in water using a UV-2550 UV-Vis spectrometer (Shimadzu, Japan), and the drug incorporation efficiency was calculated using the following Equation.
$$\mathrm{D}\mathrm{r}\mathrm{u}\mathrm{g} \mathrm{e}\mathrm{n}\mathrm{c}\mathrm{a}\mathrm{p}\mathrm{s}\mathrm{u}\mathrm{l}\mathrm{a}\mathrm{t}\mathrm{i}\mathrm{o}\mathrm{n} \mathrm{e}\mathrm{f}\mathrm{f}\mathrm{i}\mathrm{c}\mathrm{e}\mathrm{n}\mathrm{c}\mathrm{y}\left(\mathrm{\%},\frac{\mathrm{w}\mathrm{t}}{\mathrm{w}\mathrm{t}}\right)=\frac{\mathrm{D}\mathrm{O}\mathrm{X} \mathrm{m}\mathrm{a}\mathrm{s}\mathrm{s} \mathrm{i}\mathrm{n} \mathrm{t}\mathrm{h}\mathrm{e} \mathrm{m}\mathrm{a}\mathrm{t}\mathrm{e}\mathrm{r}\mathrm{i}\mathrm{a}\mathrm{l}}{\mathrm{i}\mathrm{n}\mathrm{i}\mathrm{t}\mathrm{i}\mathrm{a}\mathrm{l} \mathrm{D}\mathrm{O}\mathrm{X} \mathrm{m}\mathrm{a}\mathrm{s}\mathrm{s} \mathrm{i}\mathrm{n} \mathrm{s}\mathrm{o}\mathrm{l}\mathrm{u}\mathrm{t}\mathrm{i}\mathrm{o}\mathrm{n}}$$
The in vitro release assay was carried out using the nanocomposite and the luminescent hybrid system, at 2 different pH’s: acetate buffer solution (pH 5) and PBS (pH 7). In this procedure, 6.5 mg of the MSN/HA-Eu(2%)-Gd(1%)/DOX and MSN/HA-Eu(2%)-Gd(1%)/P(MAA)/DOX samples were added into a dialysis membrane (D9277—Sigma-Aldrich) with 0.5 mL of buffer solution, according to the pH used in the assay. The dialysis membrane with the sample was then added to 39.5 mL of buffer solution at 37 °C under continuous agitation at 50 rpm. Released DOX levels were measured by UV-Vis spectrometry at 233 nm for approximately 170 h.

The photo-Fenton performance activity of the synthesized samples was evaluated by degrading 100 mL of TC solution (10 mg/L) in the presence of a 100 mg catalyst. The initial pH (pH = 6.8) was adjusted by 0.1 mol/L HNO₃ or NaOH. The suspensions were kept in the dark for 30 min to reach the adsorption-desorption equilibrium, and then the suspensions were added with 10 mM H₂O₂ and exposed to a 300 W Xe lamp with a 420 nm cut-off filter. About 3 mL aliquots were collected and centrifuged immediately every 4 min. The absorbance of the solution was then measured at 357 nm on a Shimadzu UV-2550UV-Vis spectrometer to analyze the degradation of the TC solution. The formula for calculating the photocatalytic degradation efficiency was as follows:
where t represented time, C represented the concentration of TC, C₀ was the initial concentration of TC, and C_t was the concentration of TC at time t.
The H₂O₂ concentration was measured by a traditional cerium sulfate Ce(SO₄)₂ titration method [29 (link)].

Column chromatography (CC) was performed with silica gel (200–300, 300–400 mesh, Qingdao, China). Thin-layer chromatography (TLC) was carried out with silica gel GF-254 plates (Qingdao, China). Ultraviolet (UV) spectra were recorded on a UV2550 UV/Vis spectrometer (SHIMADZU, Kyoto, Japan). The infrared (IR) spectra (KBr) were measured using a FTIR-8400S spectrophotometer (SHIMADZU, Kyoto, Japan). The optical rotations were determined in MeOH at 20 °C, using a PerkinElmer 341 digital polarimeter (Waltham, MA, USA). Circular dichroism (CD) spectra was carried out on a J-815 spectropolarimeter (JASCO, Kyoto, Japan). The MS data were determined on a LTQ-Obitrap XL (Thermo Scientific, Bremen, Germany) mass spectrometer for HRESIMS. The obtained 1D and 2D nuclear magnetic resonance (NMR) spectra were performed on a AVIII 600 spectrometer with TMS as the internal standard (Bruker Bispin Corporation, Fallanden, Switzerland).

X-ray diffraction (XRD) was carried out on a Bruker D8 Advance X-ray diffractometer (40 kV, 30 mA) with Cu_Kα radiation (λ=1.54 Å) equipped with a PSD LynxEye silicon-strip detector. UV/Vis spectra were obtained on a Shimadzu UV-2550 UV/Vis spectrometer. The bandgap energy was estimated by using Equation (1)
where α is the absorption coefficient, hν the photon energy (h is Planck’s constant, ν is the frequency), n a constant with a value of 2 for direct-bandgap semiconductors, A a proportionality constant related to the material, and E_g the bandgap energy. The morphologies of the samples were studied on a Jeol JSM-7401F scanning electron microscope. High-resolution XPS was performed by using a Thermo Scientific K-alpha photoelectron spectrometer with monochromatic Al_Kα radiation; peak positions were calibrated to carbon (284.5 eV) and plotted with the CasaXPS software.