Application of heptamethine indocyanine small molecules with N-alkyl side chains with different chain lengths in preparation of photosensitizer for treating tumors

[0034] Example 1 Spectroscopic determination of small molecules C3-C11 of heptacyanine with different chain lengths

[0035] Accurately weigh the small molecules C3-C11 of heptamethine indocyanine with different chain lengths with a 1/10,000 analytical balance, and prepare a 10 mM dimethyl sulfoxide (DMSO) solution for later use. During the test, the dye solution was diluted to 4 μM with DMSO, and the UV absorption spectrum, fluorescence emission spectrum and fluorescence quantum yield (Φ) of compounds C3-C11 were measured by ShimadzuUV-3600 UV-Fluorescence Spectrophotometer and Lumina Fluorescence Spectrometer respectively. F). As shown in Table 1, the test results show that the maximum ultraviolet absorption wavelength and maximum fluorescence emission wavelength of all compounds are located in the near-infrared region (700-900nm), and the molar absorption coefficient (ε) is in the range of 100 000-350 000, showing excellent Light Harvesting Capability and Fluorescence Emission Properties.

[0036] Table 1 UV absorption and fluorescence properties of compounds C3~C11

[0037]

[0038] In the solution containing human serum albumin (1% HSA), it was found that the fluorescence of C3 to C11 was significantly enhanced; especially, the fluorescence enhancement of C8 was the most significant, suggesting that the strongest binding to human serum albumin HSA ( figure 1 ). Through transmission electron microscopy, it was unexpectedly found that the small molecules of heptacyanine with different chain lengths C3-C11 and HSA formed nanoparticles of different sizes, especially C8, which self-assembled in 1% HSA aqueous solution to form the most uniform size nano-dye-albumin complex (Table 2). Through the docking of HSA protein and small molecules, the potential mechanism was further explored. It was found that the minimum energy (-10.8kcal/mol) required for the binding of C8 and HSA protein, so molecule-protein binding was easy to occur, and it was beneficial to mediate the subsequent small molecules. Nanoscale self-assembly between molecules and HSA proteins (Table 2).

[0039] Table 2 Nano self-assembly of compounds C3~C11 in 1% HSA

[0040]

[0041] Example 2 Photothermal effects of small molecules C3-C11 of heptacyanine with different chain lengths

[0042] Compounds C3 to C11 were prepared as 10 mM stock solutions with DMSO and stored at -20°C. A certain amount of stock solution was drawn from the stock solutions of C3-C11 compounds prepared above and added to phosphate buffered saline (PBS, 10mM, PH=7.4) containing 1% HSA to prepare a 10 μM sample working solution, and 1.5 mL of each was added. in a centrifuge tube. Place the centrifuge tube containing the detection solution at 808nm, 1.0W/cm 2 The near-infrared laser (Laser) was irradiated for 5 minutes, and the temperature change was recorded every 30 seconds. The results are shown in figure 2 and image 3. The experimental results show that compounds C3-C11 have the effect of inducing temperature rise, among which the temperature rise effect of C8 is the most excellent, which can reach above 55℃.

[0043] Example 3 Singlet Oxygen Generation of Heptamethanine Small Molecules C3~C11 with Different Chain Lengths

[0044] SOSG probes (prepared in 100% methanol solution) were added to 2 mL of 10 μM aqueous solution of heptamethanine small molecules with different chain lengths, so that the SOSG concentration was 1.5 μM and the methanol content was 2%. and then at 1W/cm 2 The 808 nm laser was irradiated for 5 minutes, followed by excitation at 495 nm, and the fluorescence emission spectrum at 500-600 nm was immediately measured, and the generation of singlet oxygen was quantified by the fluorescence intensity of the maximum emission peak at 525 nm. like Figure 4 As shown, C3-C11 can generate a large amount of singlet oxygen after being irradiated by near-infrared 808 nm laser, among which compound C8 has the strongest singlet oxygen generation ability, which provides feasibility for realizing tumor photodynamic therapy.