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An integration of multiplexed luminescence and photocatalysis assay was proposed for the detection of acetylcholinesterase (AChE) by manipulating the coordination immobilization of photocatalytic Au nanoclusters on Eu-HOF nanorods. Eu-HOF-AuNCs served as a luminescence indicator and mimicked the enzyme toolbox for universally generating reactive oxygen species (ROS). Under light irradiation, Eu-HOF-AuNCs may accelerate the catalytic oxidation of oPD to produce more oligomers with yellow fluorescence and in situ-regulate photoluminescence variations of the indicator, in which oligomers can weaken the phosphorescence of the indicator based on overlapped spectra. By utilizing thiocholine (enzymolysis product of acetylthiocholine) to preferentially compete for ROS produced by photocatalysis of Eu-HOF-AuNCs, AChE activity was detected by the reversal of the indicator signal due to the attenuation of oPD oligomers. The emerged ratiometric fluorescence F573/F340 and F617/F340 exhibit improved sensitivity with detection limits of AChE as low as 0.09 and 0.14 U/L, respectively. Also, the cooperation of phosphorescence of Eu-HOF-AuNCs boosts detection accuracy. Serum experiments show that the Eu-HOF-AuNCs can be used to determine AChE, promoting the possibility of application in disease diagnosis. This sensor driven by photocatalysis has a great potential to be developed into a universal oxidase platform for quantifying analytes as long as the reasonable redox reaction. [ABSTRACT FROM AUTHOR]

Accurate and sensitive profiling methods for circulating tumor DNA (ctDNA) are urgently needed for human healthcare concerns. Herein, we exploit an electrochemical approach to determine the level of ctDNA in clinical samples. MnO2 nanosheets are applied as the layer modified at substrate electrode which enrich specific DNA strands labeled with electrochemical species. T7 exonuclease-assisted strand displacement amplification is introduced for recycled reactions and contributes to improved sensitivity of the electrochemical measurements. The performed work takes good use of the two-dimensional nanomaterials and expands the use of enzyme-assisted amplifications. [ABSTRACT FROM AUTHOR]

A nanoscale MOF-199 was synthesized in a simple and fast way by mixing btc triethylammonium and copper nitrate solution at room temperature and characterized by scanning electron microscopy, transmission electron microscopy, Fourier-transform infrared spectroscopy, and X-ray diffraction. The mimicking enzyme activity and the steady-state kinetics of the nanozyme were investigated. The prepared MOF-199 was a uniformly nanosized octahedron, and it exhibited excellent Cr-(VI)-activated oxidoreductase catalytic properties. MOF-199 was employed as a catalyst; in 5 min, 3,3′,5,5′-tetramethylbenzidine (TMB) was oxidized by Cr-(VI) into a bluish and oxidized TMB, which was recorded by UV–vis spectroscopy, and the mechanism was discussed. It facilitated the sensing of Cr-(VI), and a linear range of 0.1–30 μM was obtained with a limit of detection of 20 nM. The selectivity of the present method for Cr-(VI) was excellent, and its application to environmental water samples was accomplished. [ABSTRACT FROM AUTHOR]

Near-infrared (NIR) luminescent lanthanide materials hold great promise for bioanalysis, as they have anti-interference properties. The approach of efficient luminescence is sensitization through a reasonable chromophore to overcome the obstacle of the aqueous phase. The involvement of the surfactant motif is an innovative strategy to arrange the amphiphilic groups to be regularly distributed near the polymer to form a closed sensitized space. Herein, a lanthanide polymer (TCPP-PEI 70K -FITC@Yb/SDBS) is designed in which the meso-tetra(4-carboxyphenyl)porphine (TCPP) ligand serves as both a sensitizer and photocatalytic switch. The surfactant sodium dodecyl benzenesulfonate (SDBS) wraps the photosensitive polymers to form a hydrophobic layer, which augments the light-harvesting ability and expedites its photocatalysis. TCPP-PEI 70K -FITC@Yb/SDBS is subsequently applied as an amplified photocatalysis toolbox for universally regulating the generation of reactive oxygen species (ROS). Boosting 3,3',5,5'-tetramethylbenzidine (TMB) oxidation to produce blue products, a dual-mode biosensor is fabricated for improving the diagnosis of programmed death ligand-1-positive (PDL1) cancer exosomes. Exosomes were captured by Fe 3 O 4 modified by the PDL1 aptamer, enabling replacement of alkaline phosphatase (ALP)-labeled multiple hybridized chains; then, the isolated ALP triggered a hydrolysis reaction to block the generation of oxTMB. Detection sensitivity improves by 1 order of magnitude through SDBS modulation, down to 10 4 particles/mL. The sensor performed well clinically in distinguishing cancer patients from healthy individuals, expanding physiological applications of near-infrared lanthanide luminescence.

Pancreatic cancer is known to have a high mortality rate, and its early diagnosis remains challenging due to the occult location of the pancreas. Exosomes derived from pancreatic cancer cells specifically express glypican-1, which may provide a liquid biopsy opportunity for the early diagnosis of pancreatic cancer. Herein, an inductively coupled plasma mass spectrometry (ICP-MS) and photothermal dual-readout platform was proposed for the ultrasensitive and point-of-care analysis of pancreatic cancer exosomes. In our design, exosomes were specifically captured by the sandwich immunoassay, and simultaneously, alkaline phosphatase was introduced in a low-background manner. The alkaline phosphatase triggered the hydrolysis of l-ascorbic acid 2-phosphate to produce ascorbic acid, followed by the etching of Fe 3 O 4 @MnO 2 nanoflowers. As a result, the Mn 2+ generated by etching stripped off the Fe 3 O 4 and was quantified using ICP-MS. Meanwhile, the reduced Fe 3 O 4 @MnO 2 was applied for the photothermal assay by oxidizing dopamine with MnO 2 . The protocol exhibits a detection limit down to 19.1 particles mL -1 , which is the most sensitive protocol reported so far. To our knowledge, this is the first endeavor for exosome quantification using ICP-MS and photothermal methods. The developed dual-readout platform not only is capable of distinguishing pancreatic cancer patients from healthy people, but also shows excellent discernibility of individual differences at low concentrations of exosomes. This dual-readout assay is a promising platform for the ultrasensitive and point-of-care detection of exosomes in liquid biopsy-based early cancer diagnosis.

A surface-enhanced Raman scattering (SERS)-fluorescence dual-mode pH-sensing method based on Janus microgels was developed, which combined the advantages of high specificity offered by SERS and fast imaging afforded by fluorescence. Dual-mode probes, pH-dependent 4-mercaptobenzoic acid, and carbon dots were individually encapsulated in the independent hemispheres of Janus microparticles fabricated via a centrifugal microfluidic chip. On the basis of the obvious volumetric change of hydrogels in different pHs, the Janus microparticles were successfully applied for sensitive and reliable pH measurement from 1.0 to 8.0, and the two hemispheres showed no obvious interference. The proposed method addressed the limitation that sole use of the SERS-based pH sensing usually failed in strong acidic media. The gastric juice pH and extracellular pH change were measured separately in vitro using the Janus microparticles, which confirmed the validity of microgels for pH sensing. The microparticles exhibited good stability, reversibility, biocompatibility, and ideal semipermeability for avoiding protein contamination, and they have the potential to be implantable sensors to continuously monitor pH in vivo.

O-linked β-N-acetylglucosamine (O-GlcNAc) is a ubiquitous post-translational modification of proteins in eukaryotic cells. Despite their low abundance, O-GlcNAc-modified proteins play many important roles in regulating gene expression, signal transduction, and cell cycle. Aberrant O-GlcNAc proteins are correlated with many major human diseases, such as Alzheimer's disease, diabetes, and cancer. Because of the extremely low stoichiometry of O-GlcNAc proteins, enrichment is required before mass spectrometry analysis for large-scale identification and in-depth understanding of their cellular function. In this work, we designed and synthesized a novel thermosensitive immobilized triarylphosphine reagent as a convenient tool for efficient enrichment of azide-labeled O-GlcNAc proteins from complex biological samples. Immobilization of triarylphosphine on highly water-soluble thermosensitive polymer largely increases its solubility and reactivity in aqueous solution. As a result, facilitated coupling is achieved between triarylphosphine and azide-labeled O-GlcNAc proteins via Staudinger ligation, due to the increased triarylphosphine concentration, reduced interfacial mass transfer resistance, and steric hindrance in homogeneous reaction. Furthermore, solubility of the polymer from complete dissolution to full precipitation can be easily controlled by simply adjusting the environmental temperature. Therefore, facile sample recovery can be achieved by increasing the temperature to precipitate the polymer-O-GlcNAc protein conjugates from solution. This novel immobilized triarylphosphine reagent enables efficient enrichment and sensitive detection of more than 1700 potential O-GlcNAc proteins from HeLa cell using mass spectrometry, demonstrating its potential as a general strategy for low-abundance target enrichment.