Phototherapy holds great promise in the treatment of bacterial infections, especially the multidrug resistant bacterial infections. However, most therapeutic agents are based on the integration of individual photothermal agents and photosensitizers, always in the activated state, and generally lack bacterial specificity, resulting in uncertain pharmacokinetics and serious nonspecific damage to normal tissues. Herein, we report a pH-responsive nanoplatform with synergistic chemo-phototherapy function for smart fluorescence imaging-guided precision sterilization. pH reversible activated symmetric cyanine was designed and prepared as a bacterial-specific imaging unit and PTT/PDT-in-one agent. Meanwhile, a guanidinium-based covalent organic framework (COF) was employed as a nanocarrier and chemotherapy agent to build the intelligent nanoplatform via electrostatic self-assembly. The self-assembly of the PTT/PDT-in-one agent and the COF greatly improves the stability and blood circulation of the PTT/PDT-in-one agent and provides charge-reversed intelligent targeting ability. The developed smart nanoplatform not only enables bacterial-targeted imaging but also possesses chemo/PTT/PDT synergetic high-efficiency bactericidal effects with little side effects, showing great potential in practical applications.

Sensitive and accurate determination of aflatoxin B1 (AFB1) is of great significance to food safety and human health as it is recognized as the most toxic mycotoxin and carcinogenic. Herein, we report a ratiometric luminescence aptasensor based on dual-emissive persistent luminescent nanoparticles (PLNP) for the accurate determination of trace AFB1 in complex food samples without autofluorescence and exogenous interference. Dual-emissive PLNP ZnGa2O4:Cr0.0001 was prepared first and acted as the donor for energy transfer as well as the signal unit with phosphorescence at 714 and 508 nm (the detection and the reference signal, respectively). AFB1 aptamer was then bonded on the surface of PLNP to offer specific recognition ability. Aptamer complementary DNA modified with Cy5.5 was employed as the acceptor for energy transfer and the quenching group to eventually develop a turn-on ratiometric luminescence aptasensor. The developed ratiometric luminescence aptasensor combined the merits of long-lasting luminescence, in situ excitation and autofluorescence-free of PLNP, exogenous interference-free and self-calibration reading of ratiometric sensor, as well as the high selectivity of aptamer, holding great promise for accurate determination of trace AFB1 in complex matrix. The developed ratiometric aptasensor exhibited excellent linearity (0.05–70 ng mL–1), low limit of detection (0.016 ng mL–1), and good precision (2.3% relative standard deviation for 11 replicate determination of 1 ng mL–1 AFB1). The proposed ratiometric aptasensor was successfully applied for the determination of AFB1 in corn, wheat, peanut, millet, oats, and wheat kernels with recoveries of 95.1–106.5%.

Bacterial infections pose a serious threat to public health. The integration of photodynamic therapy (PDT) and chemodynamic therapy (CDT) has emerged as a promising means to combat bacterial infection. However,...