Hypoxia is a common characteristic of solid tumors, which is caused by the imbalance of oxygen supply and consumption. As the expression level of nitroreductase (NTR) increases in hypoxic solid tumors, NTR is one of the common biomarkers of hypoxia and widely used to evaluate the degree of tumor hypoxia. In this study, we designed and synthesized a highly water-soluble chemiluminescent probe, CL-NTR, for the detection of NTR activity in hypoxic tumors. It was found that the probe could be used to detect NTR with high sensitivity, and the total light photons increased tremendously with 6000-fold after the probe was treated with NTR. The chemiluminescence total light photons emission was directly proportional to the concentration of nitroreductase in the range of 3−55 ng/mL, with a detection limit of 0.947 ng/mL. Finally, the probe was successfully used to evaluate NTR activity in living mice by chemiluminescent imaging. In general, this probe has a remarkable response to NTR, which provides a promising method for the determination of NTR activity in vivo.

A novel chemiluminescent probe for detection of cysteine (Cys) from other biothiols has been reported by utilizing the excellent chemiluminescent Schaap’s adamantylidene-dioxetane scaffold. After careful assessment, the probe CL-Cys could detect Cys with high sensitivity and total light photons increased by 28-fold after the probe was treated with Cys, with the detection limit of 7.5 × 10–8 M. Finally, CL-Cys was further utilized for the chemiluminescent imaging of endogenous Cys in a living mouse. In general, this probe has a remarkable ability to detect Cys, which provides a valuable method for interrogation of the Cys roles in more biological and pathological processes.

Multiplex biomolecular analysis with inductively coupled plasma mass spectrometry (ICP-MS) becomes increasingly important in clinical diagnosis and single cell analysis. However, the sensitivity of ICP-MS-based immunoassay is only comparable or lower than those of fluorescence methods at the present stage. Therefore, designing elemental tags with a large number of metal atoms is necessary to achieve high-sensitive detection. In this work, we proposed a new strategy to build up elemental tag loading with hundreds of rare earth ions by coupling alkyne-DNA chains with rare earth element (REE)-DOTA complexes a click chemistry reaction. There are about 2 orders of magnitude improvement in sensitivity compared with single metal-ion tags. DNA chains with multialkynyl groups were facilely prepared by PCR synthesis. Moreover, the DNA-based elemental tags own excellent water-solubility and biocompatibility. The tags would be potentially applied to mass cytometry and clinical diagnosis.

MicroRNA was transformed into a DNA nanoflower ball by LRCA reaction for homogeneous multiplexed digital detection using flow cytometry.

The tool box of site-specific cleavage for nucleic acid has been an increasingly attractive subject. Especially, the recent emergence of the orthogonally activatable DNA device is closely related to the site-specific scission. However, most of these cleavage strategies are based on exogenous assistance, such as laser irradiation. Endogenous strategies are highly desirable for the orthogonally regulatable DNA machine to explore the crucial intracellular biological process and cell signal network. Here, we found that the accurate site-specific cleavage reaction of phosphorothioate (PT) modified DNA by using myeloperoxidase (MPO). A scissors-like mechanism by which MPO breaks PT modification through chloride oxidation has been revealed. Furthermore, we have successfully applied the scissors to activate PT-modified hairpin-DNA machines to produce horseradish peroxidase (HRP)-mimicking DNAzyme or initiate hybridization chain reaction (HCR) amplification. Since MPO plays an important role in the pathway related to oxidative stress in cells, through the HCR amplification activated by this tool box, the oxidative stress in living cells has been robustly imaged. This work proposes an accurate and endogenous site-specific cleavage tool for the research of biostimuli and the construction of DNA molecular devices.

AgNPs modified by Ru(ii) complexes possess bright red fluorescence and may act as potential lysosome-targeted theranostic agents.

Objectives In this study, a new immunoassay for the simultaneous determination of pepsinogen I (PGI) and pepsinogen II (PGII) in serum based on element labeling strategy coupled with inductively coupled plasma mass spectrometry (ICP‐MS) detection was proposed. Methods The sandwich‐type immunoassay was used to simultaneously detect PGI and PGII in serum. PGI and PGII were captured by anti‐PGI and anti‐PGII antibody immobilized on the magnetic beads and then banded with Eu 3+ labeled anti‐PGI detection antibody and Sm 3+ labeled anti‐PGII detection antibody, followed by ICP‐MS detection. Results The linear correlation coefficient ( R 2 ) of PGI and PGII standard curves was .9938 and .9911, with the dynamic range of 0‐200 ng/mL and 0‐60 ng/mL, respectively. The limit of detection for PGI and PGII was 1.8 ng/mL and 0.3 ng/mL, respectively. The average recovery was 101.41% ± 6.74% for PGI and 101.47% ± 4.20% for PGII. Good correlations were obtained between the proposed method and CLIA ( r = .9588 for PGI, r = .9853 for PGII). Conclusions We established a mass spectrometry‐based immunoassay for the simultaneous detection of PGI and PGII in a single analysis. The element tagged immunoassay coupled with ICP‐MS detection has high sensitivity, accuracy, and specificity in clinical serum sample analysis.

AbstractIntroductionElement-tagged immunoassay coupled with inductively coupled plasma-mass spectrometry (ICP-MS) detection has the potential to revolutionize immunoassay analysis in clinical detection; however, a systematic evaluation with the standard guidelines of the assay is needed to ensure its performance meets the requirements of the clinical laboratory.MethodsCarcinoembryonic antigen (CEA) was chosen for analysis using the proposed method. A systematic evaluation of the proposed assay was carried out according to the Clinical and Laboratory Standards Institute (CLSI). The 469 clinical samples were analyzed using the new method and compared with the electrochemiluminescent immunoassay (ECLIA) method.ResultsThe measurement range of the assay was 1–900 ng/mL, with a detection limit of 0.83 ng/mL. The inter-assay and intra-assay imprecision were 4.67% and 5.38% with high concentration samples, and 9.27% and 17.64% with low concentration samples, respectively. The cross-reactivity (%) for different antigens was less than 0.05%, and the recovery was between 94% and 108%. Percentage deviation of all the dilutions was less than 12.5% during linearity estimation. The interference bias caused by different substances was less than 10%. The reference interval of the assay was 0–4.442 ng/mL. Comparison with the commercial ECLIA method for clinical sample detection, the proposed method showed a correlation of 0.9878 and no significant differences between the methods were observed (p = 0.6666).ConclusionsThe ICP-MS based immunoassay was successfully developed, and the analytical performance of the assay met the requirements of the CLSI, which fully proved the clinical transferability and application of the new method.