Besides genome editing, CRISPR-Cas12a has recently been used for DNA detection applications with attomolar sensitivity but, to our knowledge, it has not been used for the detection of small molecules. Bacterial allosteric transcription factors (aTFs) have evolved to sense and respond sensitively to a variety of small molecules to benefit bacterial survival. By combining the single-stranded DNA cleavage ability of CRISPR-Cas12a and the competitive binding activities of aTFs for small molecules and double-stranded DNA, here we develop a simple, supersensitive, fast and high-throughput platform for the detection of small molecules, designated CaT-SMelor ( C RISPR-Cas12a- and aT F-mediated s mall m ol e cu l e detect or ). CaT-SMelor is successfully evaluated by detecting nanomolar levels of various small molecules, including uric acid and p -hydroxybenzoic acid among their structurally similar analogues. We also demonstrate that our CaT-SMelor directly measured the uric acid concentration in clinical human blood samples, indicating a great potential of CaT-SMelor in the detection of small molecules.

Tetraphenylethylene nanocrystals as new ECL emitters with near-infrared aggregation-induced enhanced electrochemiluminescence exhibited high ECL efficiency and excellent biocompatibility.

A highly sensitive electrochemiluminescent (ECL) aptasensor was constructed using semicarbazide (Sem) as co-reaction accelerator to promote the ECL reaction rate of CdTe quantum dots (CdTe QDs) and the co-reactant of peroxydisulfate (S2O8(2-)) for boosting signal amplification. The co-reaction accelerator is a species that when it is introduced into the ECL system containing luminophore and co-reactant, it can interact with co-reactant rather than luminophore to promote the ECL reaction rate of luminophore and co-reactant; thus the ECL signal is significantly amplified in comparison with that in which only luminophore and co-reactant are present. In this work, the ECL signal probes were first fabricated by alternately assembling the Sem and Au nanoparticles (AuNPs) onto the surfaces of hollow Au nanocages (AuNCs) via Au-N bond to obtain the multilayered nanomaterials of (AuNPs-Sem)n-AuNCs for immobilizing amino-terminated detection aptamer of thrombin (TBA2). Notably, the Sem with two -NH2 terminal groups could not only serve as cross-linking reagent to assemble AuNPs and AuNCs but also act as co-reaction accelerator to enhance the ECL reaction rate of CdTe QDs and S2O8(2-) for signal amplification. With the sandwich-type format, TBA2 signal probes could be trapped on the CdTe QD-based sensing interface in the presence of thrombin (TB) to achieve a considerably enhanced ECL signal in S2O8(2-) solution. As a result, the Sem in the TBA2 signal probes could accelerate the reduction of S2O8(2-) to produce the more oxidant mediators of SO4(•-), which further boosted the production of excited states of CdTe QDs to emit light. With the employment of the novel co-reaction accelerator Sem, the proposed ECL biosensor exhibited ultrahigh sensitivity to quantify the concentration of TB from 1 × 10(-7) to 1 nM with a detection limit of 0.03 fM, which demonstrated that the co-reaction accelerator could provide a simple, efficient, and low-cost approach for signal amplification and hold great potential for other ECL biosensors construction.

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Herein, we designed an electrochemiluminescence (ECL) biosensor with SnS quantum dots (SnS QDs) as novel emitters for the ultrasensitive assay of cytomegalovirus pp65 antibody (anti-CMV pp65) via smart circular peptide-DNA nanomachine amplification. First, the novel ECL biosensing platform was constructed by self-assembly of water-soluble, nontoxic, and earth-abundant SnS QDs on the 3D hierarchical silver nanoflowers (Ag NFs) surface, where the Ag NFs, as coreaction accelerator in the ECL ternary (SnS QDs/SO/Ag NFs) system, could efficiently boost the ECL intensity of SnS QDs. Furthermore, we designed a specific nucleic acid sequence labeled antigenic peptide to act as multifunctionalized capture probe (CP), which could specifically recognize the target antibody assisting with two auxiliary DNA strands via the proximity hybridization of DNA motifs to form a smart circular peptide-DNA nanomachine. Then, with the aid of nuclease, the resultant circular peptide-DNA nanomachine could initiate the subsequent cascade recycling amplification to output massive DNA products as mimic target (MT). As a result, the proposed ECL biosensor for anti-CMV pp65 detection exhibited high sensitivity with a wide linear range from 1 fM to 100 nM and a low detection limit (0.33 fM). Importantly, this work not only first utilized SnS QDs as promising ECL emitters for biosensing platform construction but also opened an efficient way for highly sensitive and selective detection of antibody in disease diagnosis and clinical analysis.