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The development of some sensitive methods for MUC1 is critical for preclinical diagnosis of tumors. In this experiment, we built a triple-amplified electrochemical aptasensor to achieve sensitive detection of MUC1, which was based on exonuclease III (Exo III)-assisted with strand displacement reaction and enzyme catalytic strategy. Firstly, with the help of Exo III, MUC1 and aptamer could be recycled during the cycle I, the single stranded DNA-1 (S-1) was produced during the process and was introduced to the hybride reaction on the electrode. Secondly, during the cycle II, strand displacement reaction was triggered on the electrode with the adding of hairpin DNA-2 (H-2). Thirdly, after the gold nanoparticles (AuNPs)-DNA-enzyme conjugates hybrided with the H-2 on the electrode, the AuNPs-DNA-enzyme conjugates could act as signal probe to produce electrochemical catalytic signal. We used the fabricated triple-amplified electrochemical aptasensor that could detect MUC1 from 0.1 pg mL−1 to 10 ng mL−1 with the detection limit of 0.04 pg mL−1 under the optimized experimental conditions. The constructed triple-amplified electrochemical aptasensor could be applied in real samples determination. Besides, the strategy can be applied to detect other proteins for health monitoring. Image 1 • The proposed electrochemical aptasensor achieved sensitive detection of MUC1. • The Exo III-assisted cycling and strand displacement reaction improved the sensitivity of MUC1 detection. • The AuNPs-DNA-enzyme conjugates could act as signal probe resulted in significant signal output. • The aptasensor could be applied in real samples determination and hold great potential for the detection of other proteins. [ABSTRACT FROM AUTHOR]

• The dual-amplified biosensor achieved ultrasensitive PPase detection and inhibitors screening. • One-pot synthesis of AuNCs-MnO 2 nanoflakes with peroxidase-like characteristics provided an effective catalytic platform. • Enzymatic hydrolysate-induced Cu2+ release from Cu2+–PPi complex opened Cu2+-DNAzymes amplification process. • Cu2+-DNAzymes and Exo III built a signal-on detection mode that inproved the sensitivity and selectivity of biosensor. A novel dual-amplified electrochemical biosensor based on Exonuclease III (Exo III) and Cu(II)-dependent DNAzymes (Cu2+-DNAzymes) was developed for ultrasensitive electrochemical evaluation of pyrophosphatase (PPase) activity with the help of one-step synthesis of BSA-directed gold nanoclusters-manganese dioxide (AuNCs-MnO 2) nanoflakes with peroxidase-like characteristics as a catalytic platform. For biosensor preparation, under the catalytic hydrolysis of the PPase, copper ion (Cu2+) was released from the Cu2+-coordinated pyrophosphate ions (Cu2+–PPi) complex which was formed by the coordination reaction of copper ion (Cu2+) and pyrophosphate ions (PPi). The released Cu2+, acting as an indispensable cofactor, could activate Cu2+-DNAzymes to turn on the amplification process and then generated the single-stranded product (S1) that hybridized to the hairpin-type capture probe (HP1). Subsequently, the addition of Exonuclease III (Exo III) enabled the reuse of S1 and produced the final cleavage fragment, which closely linked the functionalized AuNCs-MnO 2 nanoflakes to the electrode surface. The superior peroxidase-like characteristics of nanoflakes provided stable catalytic signal output and realized electrochemical monitoring of PPase activity with a detection limit of 0.0058 mU/mL. Importantly, the biosensor also had a good performance in inhibitors screening of target PPase. The use of AuNCs-MnO 2 nanoflakes instead of natural enzymes combined with DNAzymes amplification strategy offered more possibilities for the detection of various biomolecules. [ABSTRACT FROM AUTHOR]

In this study, two biological template molecules and two common short-chain imidazolium ionic liquids with amphipathy were selected to synthesize four different types of metal nanoclusters (MNCs), which were templated on a biological molecule/imidazolium ionic liquids (ILs) complex with properties enhancement. The fluorescence intensity and stability of the MNCs were improved in different degrees via this simple and fast protocol. The fluorescence intensity of AgNCs was significantly enhanced primarily due to aggregation-induced emission (AIE), and it was attributed to the shrinking size and donation of delocalized electrons for other MNCs. Different template molecule must match with appropriate ILs to form a steady complex that stabilizes the MNCs. The stability of the MNCs was improved, especially for AuNCs, because biological molecule/imidazolium ILs complex was found to be an effective barrier in protecting the MNCs from quenching interactions. Compared to conventional cationic surfactant (sodium dodecyl sulfate, SDS), these imidazolium ILs exhibited superior properties enhancement of the nanomaterials. MNCs with excellent properties could be applied in bioanalysis, especially in fluorescence imaging in vitro, because of their undisturbed and durable optical signal. [ABSTRACT FROM AUTHOR]