Lijuan Bai

Conventional receptor-targeted fluorescent probes have shown promise in tumor imaging, yet achieving a high tumor-to-normal (T/N) tissue ratio in vivo remains challenging due to limited biomarker density on tumor cell membranes. Here, we present an in situ assembly strategy of bioorthogonal-functionalized chimeric artificial receptors (BCARs) that locally constructs BCARs on tumor surfaces, which amplify fluorescence signals and enable high-contrast imaging. Rapid, selective membrane engineering under physiological conditions increases effective receptor density, enhancing fluorophore binding and tumor visualization. Mechanistic studies reveal that BCARs exhibit exceptional membrane retention and spatial precision, sustaining signal amplification in heterogeneous tumor microenvironments. In air-pouch and orthotopic bladder cancer models, BCARs notably improve the T/N imaging ratio and tumor boundary delineation. Translational validation with surgical specimens from 14 patients with bladder cancer confirms clinical feasibility. This work establishes a versatile platform for on-site receptor reprogramming and signal amplification, offering a powerful tool for high-contrast tumor margin detection.

Chloramphenicol (CAP), a broad-spectrum antibiotic derived from Streptomyces, readily persists and accumulates in humans through pathways such as the food chain, leading to significant toxic effects. Herein, a novel electrochemiluminescence (ECL) aptasensor based on the signal "ON-OFF-ON" strategy is proposed for CAP detection in food. We utilized the immobilization capacity and enzyme-mimicking activity of iron-lanthanum doped prussian blue analogue (Fe-La PBA) to catalytically enhance the luminol-H₂O₂ luminescent system, thereby engineering the composite nanozyme-based luminophore (luminol-Au@Fe-La PBA). Moreover, polydopamine (PDA)-coordinated cadmium sulfide (CdS) decorated with gold nanoparticles (Au@CdS/PDA) serves as an energy acceptor to quench the signal from emitter luminol-Au@Fe-La PBA. Firstly, the luminol-Au@Fe-La PBA emitter was immobilized on a glassy carbon electrode (GCE), providing a strong initial ECL signal and serving as a platform for anchoring cDNA hybridized with the aptamer (Apt). Then the specific quenching probe (Apt-Au@CdS/PDA) was introduced, leading to substantial signal reduction. Upon the action of CAP, the dissociation of the Apt-cDNA hybrid duplex led to the detachment of the quenching probe from the electrode surface, thereby restoring the ECL signal intensity. The aptasensor demonstrated a linear response over a concentration range of 10 to 10⁷ pg mL^- 1, and LOD was 1.18 pg mL^- 1, exhibiting satisfactory recoveries in various food samples and quality control samples.

Non-sputum-based diagnostic tests for tuberculosis (TB) are critical to global TB control. Herein, we developed an electrochemical aptasensor for detecting the ESAT-6 antigen of Mycobacterium tuberculosis (MTB) in human serum, using NiMn-layered double hydroxides@palladium nanoparticles (NiMn-LDHs@PdNPs) as a high-performance signal enhancer. NiMn-LDHs@PdNPs were synthesized via spontaneous in situ reduction, which requires no toxic reagents or complex equipment. This design not only addresses the limitations of insufficient active sites and slow electron transfer in layered double hydroxides (LDHs) but also mitigates the agglomeration tendency of palladium (Pd) nanoparticles, thereby enabling synergistic peroxidase-like activity and, importantly, relative spatial decoupling of recognition sites from catalytic sites. Functionalization with aptamers targeting the MTB ESAT-6 antigen did not significantly impair its catalytic activity. Employing a classic sandwich configuration, the aptasensor exhibited a wide linear detection range of 75 pg/mL to 10 ng/mL with a low limit of detection (LOD) of 0.629 pg/mL, alongside excellent specificity, stability, and reproducibility. In clinical validation, it successfully distinguished 14 TB patients from 14 healthy donors with 100% accuracy and outperformed enzyme-linked immunosorbent assay (ELISA). This work provides a high-performance non-sputum-based tool for TB diagnosis and advances the design of nanozyme-based biosensors. Graphical abstract

Bioorthogonal-based prodrug activation strategy holds great potential in reducing the severe side effects of chemotherapy and has been widely applied in the development of in situ personalized cancer vaccines. However, current strategies mainly focus on the caging and release of cytotoxic drugs, while the simultaneous enhancement of drug accumulation and penetration within tumors remains underexplored. Here, we modularly design a tetrazine (Tz)-modified peptide (TMP) capable of cascade responsiveness to the tumor microenvironment and biomarkers, leading to the in situ self-assembly of an artificial topological nanostructure (ATNs) catalytic system on the tumor cell surface. This system significantly increases the local concentration of bioorthogonal handles (Tz), thereby improving the activation efficiency of the prodrugs trans-cyclooctene (TCO)-doxorubicin (Dox) and TCO-imiquimod (IMQ). We demonstrated that activated Dox induced immunogenic cell death (ICD) by releasing tumor-associated antigens (TAAs), while activated IMQ further amplified immune stimulation, leading to tumor ablation. Additionally, ATNs inhibit tumor cell migration, regulate tumor tissue permeability, and ultimately promote the penetration of the activated drugs. In vivo results demonstrated that the ATNs catalytic system enhanced drug penetration by 7.8-fold in tumor tissues and exhibited excellent safety and selectivity, leading to markedly improved survival outcomes. Moreover, this system also showed promising therapeutic effects in preventing tumor recurrence. We postulate that the synergistic integration of in situ self-assembly and bioorthogonal catalysis offers great potential for the safe and effective development of in situ cancer vaccines and holds promise as a universal prodrug delivery platform for cancer therapy.

A novel ternary electrochemiluminescence (ECL) aptasensor was creatively proposed for florfenicol (FF) detection, on account of the manganese-nitrogen dual-doped carbon dots (Mn-NHCDs) emitter and the facilitation of triethylamine (TEA) by zinc oxide (ZnO). First, Mn-NHCDs with low excitation potentials and excellent electrochemical luminescence properties were synthesized. Then, a newly formulated ZnO with an enlarged specific surface area and an appropriate mesoporous structure was utilized to load Mn-NHCDs, thereby diminishing the leakage of Mn-NHCDs and stabilizing the luminescence within the system. More importantly, ZnO can serve as a new co-reaction accelerator for TEA to improve the reaction rate of Mn-NHCDs with TEA efficiently. Furthermore, owing to the overlap of spectra, we employed an ECL resonance energy transfer (ECL-RET) strategy, with the Mn-NHCDs/ZnO as the donor and black hole quencher (BHQ) as the acceptor. The ECL biosensor illustrates an extremely selective and sensitive determination of FF from 1.00 fg mL⁻¹ to 10.0 ng mL⁻¹ and a detection Limit of 0.413 fg mL⁻¹. We envision that our aptasensor will provide substantial assurance concerning food safety.