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Cardiac troponin I (cTnI) is a gold-standard marker for the detection of acute myocardial infarction (AMI). Accurate and timely detection of cTnI is particularly important for AMI diagnosis and therapy. Herein, based on the dual-capacity (electro-catalysis and catalytic degradation) of PtPd@ZrN@COF to toluidine blue (TB), we developed novel electrochemical and enzyme-linked immunosorbent assay (ELISA) methods for ultrasensitive detection of cTnI. In the electrochemical sensor, polyaniline-coated cerium oxide loaded with gold nanoparticles (Au@PANI@CeO 2) were used as a substrate platform for immobilizing antibodies (Ab1), and PtPd@ZrN@COF loaded with the affinity peptide (Pep) of cTnI and TB (Pep/TB/PtPd@ZrN@COF) was the probe material for signal amplification of the sensor. Using the 'peptide-cTnI-Ab1′ sandwich biosensor, we successfully detected cTnI in a concentration range of 0.00001–50 ng·mL−1 with an ultralow detection limit (LOD) of 3.3 fg·mL−1. In addition, a sandwich ELISA was constructed by 96-well plate using Pep/PtPd@ZrN@COF as the probe molecule for cTnI detection, showing a detection range of 0.00001–5 ng·mL−1 and a LOD of 3.3 fg·mL−1. Both detection methods presented excellent accuracy, selectivity, reproducibility, and stability, providing a potential application in clinical diagnosis of AMI. [Display omitted] • An electrochemical/colorimetric dual-mode sensing strategy for cTnI was proposed. • The sensor was based on electro-catalysis and degradation of PtPd@ZrN@COF to TB. • The dual-mode sensor showed ultralow LOD of 3.3 fg mL−1 for cTnI. • The assay provided a potential detection for diagnosis of cardiovascular disease. [ABSTRACT FROM AUTHOR]

• An ultrasensitive electrochemical cytosensor for cancer cell detection was developed. • The sensor was based on host-guest recognition. • The detection limit of the sensor was 36 cells mL−1. • The sensor was successfully adopted to determine cancer cell in real sample. • The sensor showed high sensitivity, good stability, and favorable reproducibility. The detection of tumor cells plays an important role in the early diagnosis and treatment of cancer. In this paper, we reported a novel cytosensing platform based on the supermolecular recognition using p-sulfonated calix 8 arene (SCX8)/polydopamine (PDA) /black phosphorene (BPene) nanocomposite as a receptor for cancer cells. Then, dopamine was in situ polymerized on the BPene surface to construct the BPene@PDA nanocomposite. Furthermore, SCX8 was functionalized with BPene@PDA to produce BPene@PDA − SCX8 nanocomposite. The SCX8 in BPene@PDA − SCX8 can bind to folic acid (FA) and form a stable BPene@PDA − SCX8·FA conjugate through host-guest recognition. Cancer cells can bind to the BPene@PDA − SCX8·FA modified electrode through FA and the folic receptor (FR) on the cancer cells by forming an SCX8−FA − FR sandwich-type conjugate, resulting in increased impedance that was proportional to the cell amount. Therefore, cancer cells were detected. The cytosensor exhibited a linear relation with LNCaP cells concentration within the range of 2 × 102 to 1 × 105 cells mL−1 with a detection limit of 36 cells mL−1. The constructed cytosensing platform demonstrated good sensitivity, acceptable stability, and favorable reproducibility due to specific supramolecular recognition, which has the potential applications in cancer recognition and diagnosis. [ABSTRACT FROM AUTHOR]

The pH of silage microenvironment is protean which affects the concentration of mycophenolic acid (MPA) that is an animal health-threatening mycotoxin produced by Penicillium roqueforti. This inspired us to develop a fast portable intelligent method for electrochemical detection of MPA in silage with the variable-pH microenvironment using Zn-Co MOF/Ti 3 C 2 MXene/Fe 3 O 4 -MGO coupling with machine learning (ML). Zn-Co MOF (metal organic framework), Ti 3 C 2 MXene (graphene-like titanium carbide MXene), Fe 3 O 4 -MGO (magnetic Fe 3 O 4 -graphene oxide) and their nanocompsite with excellent electrocatalytic capacity were prepared and characterized. The electrocatalytic mechanism of MPA was investigated by density functional theory (DFT) and electrochemical experiments, which clarified the most easily redox position of MPA. ML model via artificial neural network (ANN) algorithm for smart output of MPA through input of pH was discussed that adapt to the variable-pH microenvironment and realize intelligent analysis of MPA in silage with the variable-pH microenvironment. R2 near 1, lower both RMSE and MAE, and higher RPD value demonstrate the good predictive performance and high predictive accuracy of the proposed ANN model. This will provide a fast portable wireless intelligent sensing analytical technology for detecting hazardous substances in diverse complicated and changeable outdoor microenvironments [Display omitted] • A Zn-Co MOF/Ti 3 C 2 MXene/Fe 3 O 4 -MGO/GCE for detection of MPA in variable-pH silage. • ML model for mining relationship between variable pH and MPA concentration was built. • The theoretical calculation on the electrocatalytic mechanism of MPA was proposed. [ABSTRACT FROM AUTHOR]

Lung cancer is the leading cause of cancer-related death around the world. The circulating tumor DNA (ctDNA) of EGFR L858R in plasma is crucial for development, targeted drug therapy, and prognosis of non-small cell lung cancer, the main type of lung cancer. Accurately detecting ctDNA using conventional methods is challenging due to its characteristics, such as considerably short size, extremely low level, and short half-life. Thus, developing a rapid, accurate, and cost-effective method for ctDNA EGFR L858R detection is urgently needed. Herein, we developed an electrochemical biosensor of ctDNA EGFR L858R based on the CRISPR/Cas12a system and MB/Fe 3 O 4 @COF/PdAu nanocomposites. The CRISPR/Cas12a system played roles in the precise recognition of ctDNA targets and indistinguishable cleavage of single-stranded DNA. Additionally, the MB/Fe 3 O 4 @COF/PdAu nanocomposite has good catalytic activity and signal amplification performance. The proposed electrochemical biosensor showed high specificity, stability, and selectivity. Notably, the limit of detection of the proposed biosensor was 3.3 aM. The detection results of 25 clinical samples showed that 22 and 20 positive samples were detected by electrochemical detection and droplet digital polymerase chain reaction, respectively. Therefore, we established a high-precision, reliable, and convenient method for ctDNA detection, which has a potential application in the diagnosis and prognosis of cancer. [Display omitted] • Electrochemical sensor for ctDNA mutation of lung cancer was developed based on CRISPR/Cas12a. • CRISPR/Cas12a system played key roles in the precise recognition of target ctDNA. • The signal of biosensor was amplified by the good catalytic activity of Fe 3 O 4 @COF/PdAu nanocomposite. • The proposed biosensor showed high specificity, stability, and selectivity. [ABSTRACT FROM AUTHOR]