Caifeng Ding

Innovatively designing an amino acid–antibody recognition platform for specific analysis can avoid interferences from biological matrices in clinical detection and prevent signal drift, which is caused by the existing detection methods of adsorption differences and in-situ reactions. Meanwhile, unlike indirect signal responses, signal changes are directly linked to target concentrations can avoid errors caused by environmental factors and further improve detection sensitivity. Thus, in this work, a specific amino acid detection platform driven by target was developed using the self-assembled difunctional V type DNA-antibody response unit for glycine (Gly) ultrasensitive detection. Specifically, the specific recognition of Gly triggered the closure of V-shaped antibody–DNA tweezer nanodevice, shortening the distance between [Ag18H16(TPP)10]2+ (Ag NCs) and Fe11(μ4-O)4(μ-O) (Fcdc)8(μ2-OCH3)3•DMF (Fe11–Fcdc) to induce resonance energy transfer, thereby quenching the signal of Ag NCs. Meanwhile, the enzymatic reaction between Gly and its amino acid oxidase in situ generated H2O2, which was further catalyzed by Fe11–Fcdc via Fenton-like reaction to produce more •OH, significantly amplifying the signal of luminol. Benefiting from this target-driven direct response and dual-functional Fe11–Fcdc, the proposed ratio-sensor achieved sensitive detection of Gly in a wide concentration range from 5 fg/mL to 1 μg/mL with a detection limit of 3.28 fg/mL (S/N = 3). These realized the efficient diagnosis for breast cancer, and provided a feasible method to clinical analysis of other amino acids in complex biological environments.

The single-signal multistate conversion sensing mode not only improves detection sensitivity but also features a simple construction process and can effectively eliminate nonspecific signal interferences. The change of molecular structure and generation of new molecules are able to regulate the activation and inhibition of the resonance energy transfer (RET) mechanism more easily through the conversion of energy levels, thus realizing the on–off–on mode. In this work, a controlled release strategy was used to trigger the self-assembly of Bi2S3/BiOI heterojunctions via the release of Na2S, resulting from the specific recognition between carbohydrate antigen 242 (CA242) and its antibody. The formation of the Bi2S3/BiOI heterojunction changed the energy level of BiOI, thereby inhibiting the RET mechanism between the [Ru(dcbpy)3]Cl2 hydrogel (Ru-Hydrogel) and BiOI, and restoring the signal, achieving the on–off–on mode of the sensor. It was an effective method to directly relate the concentration of the target CA242 (10–4–103 U/mL) to the multistate conversion of the signal. The limit of detection of this sensor for CA242 reached 1.57 × 10–4 U/mL (S/N = 3), demonstrating high sensitivity. This study provided an innovative sensing strategy for fabricating electrochemiluminescence sensors in the on–off–on mode and offered a feasible method for the high-sensitivity detection of biomarkers in the analysis field.

Despite the operational advantages of liquid photonic crystals (LPCs) over solid counterparts for dynamically tunable structural color, their fragility and lack of structural stability remain critical bottlenecks. In this work, we overcome these limitations using magnetic nanoparticle-assembled LPCs that combine enhanced mechanical stability with full-visible-spectrum three-dimensional structural coloration achieved via precise control over particle size and concentration. Moreover, we introduce a dual-variable magnetic modulation strategy that operates through two modalities. Field strength (0-272 Gs) and field orientation (0°-90°) each enable modulation of both peak wavelength and intensity. Scanning electron microscopy reveals distinct particle arrangements under 0° and 90° field orientations, confirming that the orientation-dependent optical response originates from reconfigurable microscopic structures. This suggests that magnetic field orientation modulation can be achieved in three-dimensional PCs assembled from isotropic magnetic nanoparticles, offering a dual-variable magnetic modulation from strategies that rely on anisotropic particle design. Notably, the magnetically induced PCs exhibit substantially enhanced resistance to mechanical disturbances compared to their non-induced counterparts. Leveraging these capabilities, we demonstrate mechanically stabilized display using capillary-confined LPCs. These LPCs exhibit reversible color switching under magnetic actuation, which maintains optical signal integrity under the mechanical shear force. By integrating full-visible-range coloration, dual-variable magnetic modulation, and enhanced mechanical stability, this work establishes a versatile platform for adaptive displays, anti-counterfeiting, and robust optical sensing.

A ratiometric electrochemiluminescence (ECL) sensor with a self-calibration function can significantly enhance the detection accuracy of analytes. However, the requirement for two suitable ECL emitters and their corresponding coreactants often limits its practical applicability. In this study, luminol was employed as a single ECL emitter combined with the electro-Fenton strategy to construct a ratiometric ECL sensor without exogenous coreactants. The NiCo-MOF (NC-MOF) acted as both a suitable catalyst for the oxygen reduction reaction (ORR) and a metal source, initiating the electro-Fenton reaction to generate hydroxyl radicals (OH•) and superoxide anions (O2•–), which enhanced the cathodic and anodic ECL emissions of luminol, respectively. The aptamer for the target antibiotics and its complementary strand was immobilized on the NC-MOF-based electrode, which also served as a scaffold for the in situ growth of palladium nanoparticles (Pd NPs). Target binding induced the release of the aptamer from the electrode, causing unwinding of the double-stranded DNA (dsDNA) and retention of the complementary single strand. This results in the recovery of anodic ECL emission and simultaneous suppression of the cathodic ECL signal, since Pd NPs transform O2•– into OH•, and the content of immobilized Pd NPs decreases as dsDNA unwinds. Using kanamycin (KAN) as a model analyte, quantitative detection was achieved by changing the ECL intensity ratio (Ianodic/Icathodic). To improve the sensor performance in complex natural water samples and extend its service life, bovine serum albumin@2-(Methacryloyloxy)ethyl 2-(Trimethylammonio)ethyl Phosphate (BSA@MPC) was integrated to mitigate nonspecific adsorption of interfering substances such as bacteria and proteins. The ratiometric ECL sensor exhibits a wide detection range (10 pM-100 μM), a low detection limit (4.81 pM, S/N = 3), and excellent antifouling properties. Additionally, the sensor successfully detects KAN in natural water samples, with results comparable to high-performance liquid chromatography (HPLC) analysis, demonstrating its potential for trace antibiotic detection in complex environmental matrices.

Utilizing the extrinsic electronic properties of materials can trigger ECL signal response more efficiently than structural and energy level modulation. Microcystin-LR (MC-LR) is one of the most prevalent toxins in freshwater. Herein, a highly sensitive sensor was fabricated for MC-LR detection by integrating electronic regulation and controlled release strategies. For the controlled release strategy, mesoporous silica nanoparticles (MSNs) were employed as carriers to load glutathione (GSH), with their surfaces capped by DNA strands and covalently conjugated to target antigens. Upon specific binding between the antigen and its corresponding antibody, the double-stranded DNA structure was cut by the restriction enzyme DPN1 on the antibody, triggering the controlled release of GSH. The sensor substrate was composed of a MnO2 QDs-CBMAA (M-CB) hydrogel, which possessed dual functions: antifouling capability to mitigate non-specific adsorption of irrelevant proteins and quenching the EuCu NC signal by resonance energy transfer (RET). For the electronic manipulation strategy, the released GSH reacted with MnO2 QDs in the M-CB hydrogel, reducing them to Mn2+ without a quenching effect and thereby achieving efficient signal recovery. Consequently, the sensor achieved a low limit of detection (8.56 fg/mL) and a broad detection range from 10 fg/mL to 100 ng/mL. This novel electronic manipulation strategy endowed the sensor with rapid and highly efficient signal response performance, providing a feasible method for the sensitive trace detection of pollutants.

In disease analysis, antibody and DNA modes reveal the limitations of insufficient sensitivity and accuracy, respectively, due to the susceptibility for matrix effects and the inability to effectively capture targets. A DNA-antibody bioconjugation, leveraging both complementary advantages, is a feasible resolution. This work proposed a novel self-assemble DNA-antibody nanodevice based on target-responsive DNA colocalization strategy, and the accordingly constructed diagnosis mode triggered strand displacement to raise molecular etching. This design enabled the controlled release of luminophores in the presence of the target, thereby initiating a robust self-on signal response, thus significantly improving the sensitivity and accuracy for analysis of disease. After verification with real samples and comparison with commercial methods, this model effectively resolved issues of false negativity and long analysis times that may occur in clinical diagnosis and postoperative monitoring. Therefore, it was a feasible plan to contrapose such limitations in blood sample analysis and nucleic acid analysis for serious diseases, laying a solid foundation for its potential translational application in real medical scenarios. Furthermore, the proposed strategy exhibited superior universality, meeting the early clinical diagnosis requirements of various viruses, bacteria, and disease-related biological proteins, which broadens the application scenarios of the immunoanalyzer in medical institutions.