Engineered mesoporous carbon nanospheres with tailored pore architectures for enhanced photothermal-chemotherapy synergy

The surface morphology of mC-x was characterized by scanning electron microscopy (SEM, Hitachi SU8010). The microstructure and crystallographic features of mC-x were characterized by transmission electron microscopy (TEM, JEOL JEM-2100F). Using the BET (Brunauer-Emmett-Teller) model, fit the data in the P/P0 = 0.05–0.30 range to calculate the specific surface area (SBET). Use the BJH (Barrett-Joyner-Halenda) model to process the desorption branch data to calculate the pore size distribution. Verify the pore size peak through the DFT (density functional theory) model. Take the dried mC-x powder and spread it evenly on the conductive tape and fix it on the sample stage, after cleaning the surface with argon ion sputtering (energy 1k eV, time 30 s), use an X-ray photoelectron spectrometer with monochromatic Al Kα radiation (1486.6 eV) as the excitation source, scan the full spectrum and high-resolution spectrum under the condition of analysis chamber vacuum≤5 × 10-8 mBar, perform charge correction with C1s, use Avantage software to fit the peaks and calculate the relative content of functional groups (such as C-C/C=C, C-O, C=O, O-C=O), and quantify the proportion of each component by the integral area method.The Raman spectra of mC-x were acquired using a confocal Raman spectrometer with a 532 nm excitation laser (laser power: 0.5 mW, integration time: 30 s) to balance signal intensity and minimal thermal effects. Prior to measurement, mC-x powders were uniformly dispersed in ethanol via ultrasonication (40 kHz, 15 min) and deposited onto a SiO2/Si substrate (300 nm oxide layer) to suppress fluorescence interference.Finite element analysis was conducted using COMSOL Multiphysics® software to evaluate the heat transfer behavior of mC-x, assessing its anisotropic thermal conductivity and dynamic heat dissipation characteristics.2 mg of mC-x was weighed and dispersed in 5 mL of distilled water and ultrasonicated for 30 minutes to ensure full dispersion. 5 mL of gemcitabine solution (200 ug mL-1) was added, making the total reaction system volume 10 mL, with a final drug concentration of 100 ug mL-1. The mixture was placed in a 25°C environment and stirred for 24 hours in the dark at 200 rpm.Drug release studies were conducted in vitro under simulated physiological conditions (37°C, pH 7.4) and tumor microenvironment (37°C, pH 5.0) using GEM@mC-x. The general process is as follows: accurately weigh 5 mg of the drug-loaded material GEM@mC-x, disperse it in 5 mL of the aforementioned release medium, and sonicate for 1 minute to form a uniform suspension. Extract 2 mL of the suspension into a pre-treated dialysis bag (molecular weight cut-off 5kDa), and ensure no leakage by clamping both ends. Place the dialysis bag into a beaker containing 100 mL of release medium, and place the beaker in a constant temperature shaking bed (37°C, 100 rpm) for drug release in the dark. Samples were taken at 0.5, 1, 2, 4, 8, and 12 hours, and near-infrared laser (808 nm, 1.0 W cm-2) was used to trigger the release. At 0.5 and 4 hours from the start of drug release, the laser was irradiated for 5 minutes each time. Each time, 2 mL of liquid was removed from the beaker, filtered, and analyzed using HPLC (method same as drug loading verification) for detection. At the same time, 2 mL of the same release medium at the same temperature was added to the reaction system to maintain a constant total volume.mC-x was dispersed in deionized water at gradient concentrations (25/50/100 μg mL-1) and ultrasonicated for 30 minutes until no obvious aggregation was observed. The solution was then injected into a quartz cuvette, and the absorption spectrum was measured using a UV-Vis-NIR spectrophotometer (200-1100 nm). The absorbance values of different materials at a wavelength of 808 nm were recorded.