Polycyclic Aromatic Hydrocarbon Detection by Electrochemiluminescence Generating Ag/TiO2 Nanotubes

A quantitative proteomics-based competition binding assay to characterize pITAM-protein interactions

Characterization of ligand-protein binding is of crucial importance in drug discovery. Classical competition binding assays measure the binding of a labeled ligand in the presence of various concentrations of unlabeled ligand and typically use single purified proteins. Here, we introduce a high-throughput approach to study ligand-protein interactions by coupling competition binding assays with mass spectrometry-based quantitative proteomics. With the use of a phosphorylated immunoreceptor tyrosine-based activation motif (pITAM) peptide as a model, we characterized pITAM-interacting partners in human lymphocytes. The shapes of competition binding curves of various interacting partners constructed in a single set of quantitative proteomics experiments reflect relative affinities for the pITAM peptide. This strategy can provide an efficient approach to distinguish specific interacting partners, including two signaling kinases possessing tandem SH2 domains, SYK and ZAP-70, as well as other SH2 domain-containing proteins such as CSK and PI3K, from contaminants and to measure relative binding affinities of multiple proteins in a single experiment.

Electrochemiluminescence detection of c-Myc mRNA in breast cancer cells on a wireless bipolar electrode

Electrochemiluminescence (ECL) on bipolar electrode (BPE) is a sensitive, portable, and low-cost approach which has been employed to detect DNA and proteins. Here, we develop an ultrasensitive method for intracellular mRNA assay based on mRNA-mediated reporter DNA liberation and Ru(bpy)3(2+)-conjugated silica nanoparticles (RuSi@Ru(bpy)3(2+)) tag-based signal amplification.

A novel aptasensor for the detection of adenosine in cancer cells by electrochemiluminescence of nitrogen doped TiO2 nanotubes

The highly enhanced electrochemiluminescence from a nitrogen doped TiO(2) nanotube array has been reported for the first time, and successfully applied to develop an ultrasensitive ECL aptasensor for the detection of adenosine in cancer cells.

Sensitive electrochemiluminescence detection of c-Myc mRNA in breast cancer cells on a wireless bipolar electrode

We report an ultrasensitive wireless electrochemiluminescence (ECL) protocol for the detection of a nucleic acid target in tumor cells on an indium tin oxide bipolar electrode (BPE) in a poly(dimethylsiloxane) microchannel. The approach is based on the modification of the anodic pole of the BPE with antisense DNA as the recognition element, Ru(bpy)(3)(2+)-conjugated silica nanoparticles (RuSi@Ru(bpy)(3)(2+)) as the signal amplification tag, and reporter DNA as a reference standard. It employs the hybridization-induced changes of RuSi@Ru(bpy)(3)(2+) ECL efficiency for the specific detection of reporter DNA released from tumor cells. Prior to ECL detection, tumor cells are transfected with CdSe@ZnS quantum dot (QD)-antisense DNA/reporter DNA conjugates. Upon the selective binding of antisense DNA probes to intracellular target mRNA, reporter DNA will be released from the QDs, which indicates the amount of the target mRNA. The proof of concept is demonstrated using a proto-oncogene c-Myc mRNA in MCF-7 cells (breast cancer cell line) as a model target. The wireless ECL biosensor exhibited excellent ECL signals which showed a good linear range over 2 × 10(-16) to 1 × 10(-11) M toward the reporter DNA detection and could accurately quantify c-Myc mRNA copy numbers in living cells. C-Myc mRNA in each MCF-7 cell and LO2 cell was estimated to be 2203 and 13 copies, respectively. This wireless ECL strategy provides great promise in a miniaturized device and may facilitate the achievement of point of care testing.

Disposable electrochemiluminescent biosensor using bidentate-chelated CdTe quantum dots as emitters for sensitive detection of glucose

A novel disposable solid-state electrochemiluminescent (ECL) biosensor was fabricated by immobilizing glucose oxidase and surface-unpassivated CdTe quantum dots (QDs) on a screen-printed carbon electrode (SPCE). The surface morphology of the biosensor was characterized with scanning electron microscopy and atomic force microscopy. With dissolved O(2) as an endogenous coreactant, QDs/SPCE showed strong ECL emission in pH 9.0 HCl-Tris buffer solution with low ECL peak potential at -0.89 V. The ECL intensity was twice that with hydrogen peroxide as coreactant at the same concentration. This phenomenon meant the ECL decreased upon consumption of dissolved O(2) and thus could be applied to the construction of oxidase-based ECL biosensors. With glucose oxidase as a model enzyme, the biosensor showed rapid response to glucose with a linear range of 0.8 to 100 μM and a detection limit of 0.3 μM. Further detection of glucose contained in human serum samples showed acceptable sensitivity and selectivity. This work provided a promising application of QDs in ECL-based disposable biosensors.

Facile on-site detection of substituted aromatic pollutants in water using thin layer chromatography combined with surface-enhanced Raman spectroscopy

A novel facile method for on-site detection of substituted aromatic pollutants in water using thin layer chromatography (TLC) combined with surface-enhanced Raman spectroscopy (SERS) was explored. Various substituted aromatics in polluted water were separated by a convenient TLC protocol and then detected using a portable Raman spectrometer with the prepared silver colloids serving as SERS-active substrates. The effects of operating conditions on detection efficacy were evaluated, and the application of TLC-SERS to on-site detection of artificial and real-life samples of aromatics/polluted water was systematically investigated. It was shown that commercially available Si 60-F(254) TLC plates were suitable for separation and displayed low SERS background and good separation efficiency, 2 mM silver colloids, 20 mM NaCl (working as aggregating agent), 40 mW laser power, and 50 s intergration time were appropriate for the detection regime. Furthermore, qualitative and quantitative detection of most of substituted aromatic pollutants was found to be readily accomplished using the developed TLC-SERS technique, which compared well with GC-MS in terms of identification ability and detection accuracy, and a limit of detection (LOD) less than 0.2 ppm (even at ppb level for some analytes) could be achieved under optimal conditions. The results reveal that the presented convenient method could be used for the effective separation and detection of the substituted aromatic pollutants of water on site, thus reducing possible influences of sample transportation and contamination while shortening the overall analysis time for emergency and routine monitoring of the substituted aromatics/polluted water.