The controlled release strategy can make the constructed sensor have the function of self-on/off, which has an obvious effect on improving the sensitivity in immunoassays. Metal organic gels (MOGs) are the most noteworthy. They are materials with ultrahigh surface area, highly dispersed atomical metal sites, and well-defined porosity and can be used as an efficient luminophore to cause the developed sensor to have good hydrophilicity and adjustability, thus further improving the detection sensitivity. In this work, a novel on/off electrochemiluminescence (ECL) gel aptasensor was constructed using the Cys-[Ru­(dcbpy)3]2+ gel as a luminophore, ZnS quantum dots (QDs) as quenchers, and aminated mesoporous silica nanocontainers (SiO2–NH2) as carriers of controlled release for prostate specific antigen (PSA) detection. Specifically, the ssDNA and PSA aptamer made up clamp-like molecules to block holes of the SiO2–NH2 after encapsulating the quencher ZnS QDs. Because of the specific binding between the PSA antigen and aptamer, the clamp-like molecules of ssDNA and the PSA aptamer were disassembled. Finally, the release of ZnS QDs was triggered, thereby realizing a self-off mode of the ECL signals under a co-reactant-free environment by ECL resonance energy transfer (ECL-RET) between the Cys-[Ru­(dcbpy)3]2+ and ZnS QDs. In addition, the quenching mechanism was confirmed by molecular orbitals from the theoretical calculation level. The detection limit of the gel aptasensor for PSA was as low as 1.01 fg/mL, showing excellent sensitivity and accuracy. These strategies provided a feasible idea for PSA and even other tumor marker immunoassays.

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An addressable label-free photoelectric immunosensor array was designed for detection of neuron specific enolase (NSE) based on TiO 2 /CdS as substrate materials. In this work, the hydrothermal synthesized TiO 2 nanorod film is evenly grown on the surface of the fluorine-doped tin oxide (FTO), and then CdS with a narrow band gap is added for sensitization through successive ionic layer adsorption reactions. The obtained TiO 2 /CdS composite materials with matched energy band structures promote the rapid electron transfer and effectively reduce the recombination of electron hole pairs, which greatly enhance the visible light absorption and increased photocurrent intensity. In order to construct a suitable sensor array, the sensitized FTO electrode is divided into multiple regions of equal size by insulating stickers, and then the addressable and continuous detection of multiple samples can be achieved. Because multiple detection regions are prepared and tested under the same conditions, the difference effectively reduces, and the sensor can realize self-calibration and obtain more accurate results. Under optimal conditions, this sensor array can detect NSE in the linear range of 0.01−100 ng mL −1 with a detection limit of 2.49 pg mL −1 (S/N = 3). The sensor array has good selectivity, stability, and reproducibility, making it a viable approach for real sample detection.

Curcumin-conjugated Au nanoparticles wrapped in zeolitic Zn2+-imidazolate cross-linked framework nanoparticles quenched the ECL of CdS-decorated TiO2 nanobelts.

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