Photothermal therapy (PTT) stands as an emerging and promising treatment modality and is being developed for the treatment of breast cancer, prostate cancer, and a series of superficial tumors. This innovative approach harnesses photothermal agents (PTAs) that convert near-infrared light (NIR) energy into heat, efficiently heating and ablating localized lesion tissue. Notably, the low scattering of NIR-II (1000–1500 nm) band light within biological tissue ensures superior penetration depth, surpassing that of NIR I (700–900 nm) band light. Consequently, developing PTAs with excellent absorption performance and biocompatibility in the NIR-II band has attracted significant attention in photothermal therapy research. We successfully synthesized phosphomolybdenum blue (PMB) nanoparticles using single-strand DNA (ssDNA) as a template in this innovative study. Subsequently, we delved into this material's absorption characteristics and photothermal properties across the NIR-I and NIR-II spectral regions. Furthermore, we evaluated the therapeutic efficacy of PMB on 4T1 cells and tumor-bearing mouse models of breast cancer. Our findings revealed that PMB not only exhibits remarkable biocompatibility but also possesses stellar photothermal performance. Specifically, under 808 nm and 1064 nm laser irradiation, PMB achieved photothermal conversion efficiencies of 21.37% and 28.84%, respectively. Notably, compared to 808 nm laser irradiation, even when transmitting through a 2 mm thick tumor tissue homogenate, the 1064 nm laser irradiation maintained a robust tumor ablation effect. What's more, PMB possesses critical pH-responsive degradation properties. For instance, PMB nanoparticles degrade rapidly under physiological conditions (pH 7.2–7.4) while degrading slower in the acidic tumor microenvironment (pH 6.0–6.9). This unique characteristic significantly mitigates the systemic toxicity of PMB and enhances the safety of photothermal therapy implementation. Moreover, our study represents the first instance of utilizing ssDNA as a template for synthesizing a PMB nano photothermal agent and demonstrating its exceptional tumor thermal ablation efficacy. This groundbreaking work offers novel insights into the development of safe, efficient, and pH-responsive photothermal agents for cancer therapy.
Current methods for determining dissolved reactive phosphorus (DRP) in sediment porewater mainly rely on ex-situ analysis, which can be labor-intensive and introduces errors due to changes in the concentration and morphology during sampling and transportation. Therefore, there is a clear need for in-situ measurement methods for DRP in sediment porewater. In this study, a novel in-situ analytical method was developed by combining diffusive gradients in thin-films (DGT) and digital imaging techniques, based on the classic phosphomolybdenum blue (PMB) method. During deployment, DRP in sediment porewater diffuses into the DGT device, while reducing reagent (ascorbic acid) from the diffusive gel simultaneously diffuses into the binding gel and reacts with ammonium molybdate, resulting in the formation of PMB compounds. The color of the PMB compounds was recorded in-situ using a digital imaging technique, and the resulting images were analyzed to calculate the concentration of DRP in surface sediment porewater. By using the new method, analytical data of DRP in surface sediment porewater could be quickly obtained in the field near real-time, without water sampling and any further sample treatment, transportation and instrumental analysis in laboratories. The key parameters including the loading procedure for colorimetric reagents in the gels, the concentrations of ammonium molybdate and ascorbic acid, the amount of C18, and the thickness of the C18 binding gel, were systematically optimized. The optimized method demonstrated a wide linear range (4 ‒ 1000 μmol L-1, R2=0.993), with satisfactory accuracy (-6.23% ‒ 8.68%, n = 3) and good precision (6.60% ‒ 13.46%, n = 3) at an exposure time of 60 min. The method also performed well across different salinities (0 ‒ 35) and in the presence of interfering ions (SiO32‒, AsO33‒, F‒, and S2‒). The method was successfully applied to both freshwater and seawater sediments, with results comparable to those obtained using traditional analytical methods. Overall, the proposed method provides a new strategy for in-situ determination of DRP in surface sediment porewater.
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