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Discrimination of glycoproteins with different glycans is a significant but difficult issue. We presented here a new strategy for strengthening the discrimination of glycoproteins by introducing a new signaling channel, fluorescence polarization (FP), into a "single probe with three signaling channels" sensor array. The single probe was aminophenylboronic-acid-conjugated poly (acrylic acid)-Mndoped ZnS quantum dots, and the three signaling channels were FP, room temperature phosphorescence and light scattering. Ten glycoproteins, including ovalbumin, fibrinogen, transferrin, horseradish peroxidase, vascular endothelial growth factor, immunoglobulin G, avidin, hyaluronidase, cellulase R- 10, and glucose oxidase, were involved for evaluating the discriminating capability. The introduction of the FP signaling channel improved the discriminating power of the sensor array, so that the 10 glycoproteins at 0.15 μM could be well discriminated both in PBS buffer and in the presence of human serum sample. The identification accuracy of the unknown samples was 96.25% (77 out of 80) at the 0.15 μM level and 97.50% (78 out of 80) at the 0.2 μM level. The integration of the signaling patterns with different responsive principles was demonstrated as the promising way to enhance the discrimination power of the single-probebased sensor arrays. [ABSTRACT FROM AUTHOR]

A new type of molecularly imprinted polymer (MIP)-based room-temperature phosphorescence (RTP) optosensor was developed by anchoring the MIP layer on the surface of Mn-doped ZnS quantum dots (QDs) via a surface molecular imprinting process. The synergetic combination of the RTP property of the Mn-doped ZnS QDs and the merits of the surface imprinting polymers not only improves the RTP selectivity of the Mn-doped ZnS QDs but also makes the MIP-based RTP optosensor also applicable to selective detecting of those nonphosphorescent analytes without the need for any inducers and derivatization. The new MIP-based RTP sensing protocol was applied to detect trace pentachlorophenol (PCP) in water samples without the interference of autofluorescence and scattering light of matrixes. The detection limit for PCP was 86 nM, and the precision for five replicate detections of 0.4 μM PCP was 2.8% (relative standard deviation). The recovery of spiked PCP in river water samples ranged from 93% to 106%. [ABSTRACT FROM AUTHOR]

While most research works focus on the development of quantum dots (QDs)-based fluorescence sensors, much less attention is paid to the phosphorescence properties of QDs and their potential for phosphorescence detection. In this work, the phosphorescence property of Mn-doped ZnS QDs is explored to develop a novel room-temperature phosphorescence (RTP) method for the facile, rapid, cost-effective, sensitive, and selective detection of enoxacin in biological fluids. The Mn-doped ZnS QDs-based RIP method reported here does not need the use of deoxidants and other inducers and allows the detection of enoxacin in biological fluids without interference from autofluorescence and the scattering light of the matrix. The Mn-doped ZnS QDs offer excellent selectivity for detecting enoxacin in the presence of the main relevant metal ions in biological fluids, biomolecules, and other kinds of antibiotics. Quenching of the phosphorescence emission due to the addition of enoxacin at 1.0 μM is unaffected by 5000-fold excesses of Na+ and 10000-fold excesses of K+, Mg2+, and Ca2+. Amino acids such as tryptophan, histidine, and L-cysteine at 1000-fold concentration of enoxacin do not affect the detection of enoxacin. Glucose does not affect the detection at 10000-fold concentration of enoxacin. Typical coadministers (mainly other types of antibiotics) such as ceftezole, cefoperazone, oxacillin, and kalii dehydrographolidi succinas are permitted at 50-, 10-, 100-, and 50-fold excesses, respectively, without interference with the detection of enoxacin. The precision for 11 replicate detections of 0.4 μM enoxacin is 1.8% (RSD). The detection limit for enoxacin is 58.6 nM. The recovery of spiked enoxacin in human urine and serum samples ranges from 94 to 104%. The developed Mn-doped ZnS QDs-based RTP method is employed to monitor the lime-dependent concentration of enoxacin in urine from a healthy volunteer after the oral medication of enoxacin. The investigation provides evidence that doped QDs are promising for RTP detection in further applications. [ABSTRACT FROM AUTHOR]

We presented a novel fluorescence anisotropy (FA) method for the noninvasive, effective, simple, and convenient discrimination of the symmetric and asymmetric distribution of the ligands on Mn-doped ZnS quantum dots (QDs). The symmetric or asymmetric distribution of mercaptopropionic acid (MPA) and NH2-polyethylene glycol-CH3 (PEG-m, MW 2000) was controlled by the condensation reaction of the carboxyl of MPA and the amino of PEG-m with or without the masking by the amino-functionalized silica nanoparticles. The ligand-asymmetric Janus-QDs were obtained with the masking, whereas the ligand-symmetric PEG-QDs were gained without masking. The FA values of the QDs could not only distinguish the ligand symmetric PEG-QDs from the ligand asymmetric Janus-QDs but also discriminate the QDs with a different PEG-m amount. Besides, the FA assay also has superiority over the dynamic light scattering (DLS) and photoluminescence (PL) methods in discriminating the interaction of Janus-QDs or PEG-QDs with protamine (the sensitivity of Janus-QD-3 over PEG-QD-3 was 1.60, 1.24, and 1.11 in the FA, DLS, and PL methods, respectively). [ABSTRACT FROM AUTHOR]

Integrating various enzymes with nanomaterials provides various nanohybrids with new possibilities in biosensor applications. Furthermore, the enzymatic activity and stability are also improved due to the large surface area of nanomaterials. Here we report the conjugation of glucose oxidase (GOD) onto phosphorescent Mn-doped ZnS quantum dots (QDs) using l-ethyl-3-(3-dimethylaminopropy)carbodiimide(EDC)/ JV-hydroxysuccinimide (NHS) as coupling reagents for glucose biosensing based on the effective quenching of the room temperature phosphorescence (RTP) of Mn-doped ZnS QDs by the H2O2 generated from GOD-catalyzed oxidation of glucose. The obtained biocon-jugatenotonlyprovided improved enzymatic performance with Michaelis-Menten constant of 0.70 mM but also favored biological applications because the phosphorescent detection mode avoided the interference from autofluorescence and scattering light from the biological matrix. In addition, the GOD-conju-gated Mn-doped ZnS QDs showed better thermal stability in the temperature range of 20-80 °C. The GOD-Mn-doped ZnS QDs based RTP sensor for glucose gave a detection limit of 3 μM and two linear ranges from 10 /iM to 0.1 mM and from 0.1 to 1 mM. The developed biosensor was successfully applied to the determination of glucose in real serum samples without the need for any complicated sample pretreatments. [ABSTRACT FROM AUTHOR]