Fluorescence ratiometric biosensors are valuable tools for the accurate and sensitive prediction and diagnosis of diseases. However, seldom have fluorescence ratiometric biosensors for protein and DNA been reported because of the shortage of suitable nanoscale scaffolds. Herein, a tripyridinyl RuII complex–encapsulated SiO2@polydopamine (Ru–SiO2@PDA) nanocomposite was designed as a universal platform for fluorescence ratiometric detection of DNA and protein in serum samples. The Ru–SiO2@PDA nanocomposites have a narrow size distribution, exhibit good biosafety, and are convenient for the postmodification of biorecognition elements. Under irradiation, they can emit a stable and strong luminescence at 650 nm and simultaneously quench the fluorescence emitted from the fluorophores getting close to them. Once the capture probes such as single-stranded DNA and aptamer are assembled, the fluorophores labeled on them are then brought close to their PDA shell and quenched. However, the biorecognition behaviors change the probe’s configuration and take the fluorophore far away from the PDA shell. Correspondingly, the fluorescence recovers and its ratio to the constant fluorescence reference is linear to the targets’ concentration. Using a D-catalyst and thrombin as model analytes, the Ru–SiO2@PDA-based nanoplatform shows high sensitivity and good accuracy in the serum sample analysis. Regarding these attractive properties, the Ru–SiO2@PDA nanoplatform provides a new avenue for the accurate and sensitive fluorescence assay of a wide range of targets in complex systems.
Bacterial infections represent one of the foremost threats to global human health. Furthermore, the misuse of antibiotics has exacerbated the public health crisis. Therefore, the development of high-performance novel antibacterial materials is of utmost importance. However, there are still several issues regarding the antibacterial performance and recyclability of existing antibacterial materials. To address these issues, this study synthesized a core@shell@shell@satellite structured Fe 3 O 4 @SiO 2 @polydopamine (PDA)@tannic acid (TA)@Ag nanocomposite, aiming to achieve excellent photothermal effect and synergistic antibacterial activity with silver. The composite particles exhibited improved dispersibility due to the SiO 2 coating. The modification of TA on the Fe 3 O 4 @SiO 2 @PDA achieved the uniform loading of silver nanoparticles (NPs), which significantly enhanced the photothermal conversion efficiency (η) of up to 74.9 %. Additionally, the superparamagnetic property facilitated magnetic separation, ensuring the efficient recovery and reutilization of the nanocomposites. Under low concentration and low-power near-infrared (NIR) light irradiation (808 nm, 1.0 W cm −2 ), the nanocomposite demonstrated excellent synergistic antibacterial activity, achieving efficient eradication of Escherichia coli (100 %) and Staphylococcus aureus (98 %). Furthermore, the material could be recycled up to five times without significant loss of antibacterial activity. Overall, our approach demonstrates the potential of novel multifunctional composite NPs in the treatment of bacterial infections and the sustainable application of antibacterial agents.
危险品化学品经营许可证（带存储）