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Simultaneous detection of various intracellular biomarkers is promising for early diagnosis and treatment of cancer. Herein, we develop a novel method for high specific and ultrasensitive detection of liver cancer cell‐involved mRNAs: TK1 and c‐myc based on the split primer ligation‐triggered 8‐17 DNAzyme assisted cascade rolling circle amplification. Only two targets exist simultaneously, can trigger the rolling circle amplification to improve the accuracy and sensitivity. Meanwhile, an electrochemical molecular beacon, based on the host‐guest recognition between ferrocene groups and cucurbit urils [7] (CB[7]/Fc‐MB), is used to cause a "turn‐off" electrochemical signal which is decreased by disrupting its hairpin structure. Under the optimal conditions, the detection limit of TK1 and c‐myc mRNA is as low as 0.06 nM. Moreover, this method can be used to detect the TK1 and c‐myc mRNA in HepG2 cells and distinguish between cancer cells and their normal cells, proving that the method has the potential to detect the variation of biomarkers in vivo. [ABSTRACT FROM AUTHOR]

Herein we show that by appending bulky β‐cyclodextrin (CD) groups onto sheet‐forming peptoids, we obtain cylindrical micelles that further assembly into membranes and intertwined ribbons on substrates in aqueous solution, depending on the choice of solution and substrate conditions. In situ atomic force microscopy (AFM) shows that micelle assembly occurs in two steps, starting with "precursor" particles that transform into worm‐like micelles, which extend and coalesce to form the higher order structures with a rate and a degree of cooperativity dependent on pH and Ca2+ concentration. After co‐assembly with hydrophobic 4‐(2‐hydroxyethylamino)‐7‐nitro‐2,1,3‐benzoxadiazole (NBD) donors that occupy the hydrophobic core, followed by exposure to hydrophilic Rhodamine B as acceptors that insert into cyclodextrin, the micelles exhibit highly efficient Förster resonance energy transfer efficiency in aqueous solution, thereby mimicking natural light harvesting systems. [ABSTRACT FROM AUTHOR]

Due to their unique physical and chemical properties, 2D materials have attracted intense interest for applications in filtration, sensing, nanoelectronics, and biomedical devices. Peptoids are a class of biomimetic sequence-defined polymers for which certain amphiphillic sequences self-assemble into 2D crystalline materials with properties that mimic those of cell membranes. In this study the ability of these membrane-like materials to self-repair following damage on a range of substrates is explored. In situ atomic force microscopy (AFM) is used to both create damage and image the subsequent repair process. Damage is induced by using the AFM to scribe peptoid-free patterns within a preassembled membrane. The results show here that, upon introduction of a peptoid-containing solution, for a suitable range of pH conditions, the damage is eliminated through assembly of the peptoids at the newly created edges, regardless of whether the substrates are negatively or positively charged and even in the absence of an underlying surface. The rate of the advancing edge depends on the edge orientation, the pH, and the composition of the substrate. Moreover, if the solution contains a second peptoid having an identical sequence in the hydrophobic block, repair of the defects results in nanoscale patterns of the new peptoid, even if the hydrophilic regions are distinct. Consequently, this ability to self-repair can be exploited to create nm-sized patterns of distinct functional groups within a single coherent membrane. [ABSTRACT FROM AUTHOR]

A simple and sensitive method for glucose determination was described based on the host-guest inclusive complex of cucurbit[7]uril and ferrocenemonocarboxylic acid. In this work, the mixture of cucurbit[7]uril and graphene oxide, ferrocenemonocarboxylic acid as electron transfer mediator and glucose oxidase as catalytic material were modified successively on the electrode. Under the optimized conditions, a linear response between current intensity and glucose concentrations over a range of 0.1-10 mM was obtained with a relatively low detection limit (27 µM, S/N=3). Meanwhile, this method exhibited high selectivity in the interference investigation, and the reliability and applicability in human serum samples analysis. [ABSTRACT FROM AUTHOR]

An ultrasensitive and signal-on electrochemiluminescence (ECL) aptasensor to detect target protein (thrombin or lysozyme) was developed using the host-guest recognition between a metallocyclodextrin complex and single-stranded DNA (ss-DNA). The aptasensor uses both the photoactive properties of the metallocyclodextrins named multi-tris(bipyridine)ruthenium(II)- β-cyclodextrin complexes and their specific recognition with ss-DNA, which amplified the ECL signal without luminophore labeling. After investigating the ECL performance of different multi-tris(bipyridine)ruthenium(II)- β-cyclodextrin (multi-Ru- β-CD) complexes, tris-tris(bipyridine)-ruthenium(II)- β-cyclodextrin (tris(bpyRu)- β-CD) was selected as a suitable host molecule to construct an atasensor. First, double-stranded DNA (ds-DNA) formed by hybridization of the aptamer and its target DNA was attached to a glassy carbon electrode via coupling interaction, which showed low ECL intensity with 2-(dibutylamino) ethanol (DBAE) as coreactant, because of the weak recognition between ds-DNA and tris(bpyRu)- β-CD. Upon addition of the corresponding protein, the ECL intensity increased when target ss-DNA was released because of the higher stability of the aptamer-protein complex than the aptamer-DNA one. A linear relationship was observed in the range of 0.01 pmol/L to 100 pmol/L between ECL intensity and the logarithm of thrombin concentrations with a limited detection of 8.5 fmol/L (S/N=3). Meanwhile, the measured concentration of lysozyme was from 0.05 pmol/L to 500 pmol/L and the detection limit was 33 fmol/L (S/N=3). The investigations of proteins in human serum samples were also performed to demonstrate the validity of detection in real clinical samples. The simplicity, high sensitivity and specificity of this aptasensor show great promise for practical applications in protein monitoring and disease diagnosis. [ABSTRACT FROM AUTHOR]

Based on the catalytic activity of hemin, an efficient biocatalyst, an indirect capillary electrophoresis–chemiluminescence (CE‐CL) detection method for phenols using a hemin–luminol–hydrogen peroxide system was developed. Through a series of static injection experiments, hemin was found to perform best in a neutral solution rather than an acidic or alkaline medium. Although halide ions such as Br− and F− could further enhance the CL signal catalyzed by hemin, it is difficult to apply these conditions to this CE‐CL detection system because of the self‐polymerization of hemin, as it hinders the CE process. The addition of concentrated ammonium hydroxide to an aqueous/dimethyl sulfoxide solution of hemin–luminol afforded a stable CE‐CL baseline. The indirect CE‐CL detection of five phenols using this method gave the following limits of detections: 4.8 × 10−8 mol/L (o‐sec‐butylphenol), 4.9 × 10−8 mol/L (o‐cresol), 5.4 × 10−8 mol/L (m‐cresol), 5.3 × 10−8 mol/L (2,4‐dichlorophenol) and 7.1 × 10−8 mol/L (phenol). Copyright © 2013 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Aptamers are single-stranded nucleic acid molecules that can be used for protein recognition, detection, and inhibition. Over the past decades, two thrombin-binding aptamers (15apt and 27apt) were reported by systemic evolution of ligands by exponential enrichment technique. Though many studies have been reported about the interactions between the aptamers and thrombin by atomic force microscopy, the thrombins in those studies were all immobilized by chemical agents. Recently, we developed a new method using atomic force microscopy to directly investigate the specific interactions between thrombin and its two aptamers without immobilizing the thrombin. Furthermore, the unbinding dynamics and dissociation energy landscapes of aptamer/thrombin were discussed. The results indicate that the underlying interaction mechanisms of thrombin with its two aptamers will be similar despite that the structures of 15apt and 27apt are different in buffer solution. Copyright © 2013 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Here we report on the preparation and characterization of new electrodes based on aligned carbon nanotubes (ACNTs) for hemoglobin (Hb) electrochemistry and electrocatalysis. The ACNTs are obtained by a thermal chemical vapor deposition method under normal pressure. Then the electrodes are elaborated by first sputtering a thin Au film (thickness of 200 nm) onto the top of the ACNTs, and then removing the Au layer/ACNTs from the quartz substrate with the aide of hydrofluoric acid (HF) treatment. Field emission scanning electron microscopy (FESEM) demonstrates that after nitric acid (HNO3) treatment, the nanotubes of the removed Au layer are totally tip-opened, purified and organized in a perfect vertically aligned architecture. The final ACNTs electrode is obtained by attaching the Au layer of ACNTs onto a glassy carbon electrode. Then the electrode was modified to act as a matrix for hemoglobin (Hb) immobilization and as an electrode for Hb electroanalysis by the assistance of Au nanoparticles (AuNPs) and SiO2 gel. Due to the individual specific effects of AuNPs, SiO2 gel and ACNTs, the resulting SiO2/Hb-AuNPs/ACNTs electrode showed good direct electrochemistry of Hb with an apparent MichaelisMenten constant of 0.44 mM. The electrode showed an excellent electrocatalytic activity towards H2O2, possessing a linear range from 40 µM to 4 mM and the detection limit was 22 µM based on a signal to noise ratio of 3. [ABSTRACT FROM AUTHOR]

Miraculous metallocyclodextrin: A new polynuclear metallocyclodextrin complex, tris(bpyRu)–β‐CD (bpy=bipyridine), was successfully synthesized. This complex possesses molecular‐recognition functions and unique luminescent properties. A tris(bpyRu)–β‐CD film was fabricated and utilized in a electrochemiluminescence (ECL) DNA sensor based on its molecular‐recognition and luminescence characteristics (see scheme). [ABSTRACT FROM AUTHOR]

ABSTRACT A simple and effective capillary electrophoresis-chemiluminescence (CE-CL) detection system was developed based on an ultra-fast bis(2,4,6-trichlorophenyl)oxalate (TCPO) chemiluminescence (CL) reaction (0.6 s duration) that avoided overlapping peaks and peak tailing. Through a series of static injection experiments, this unusually rapid CL reaction was ascribed to the catalytic effect of imidazole in the tetrahydrofuran solvent, which has been rarely utilized in such investigations. A possible mechanism is given to explain the results. Under the optimized conditions, rhodamine 6 G (R6G) and its hydrolysis product (R6G-COOH) could be efficiently separated through electrophoresis in 7 min, with sensitive CL detection in the proposed CE-CL system. In this way, the alkaline hydrolysis of R6G was monitored, followed by estimation of relative rate constants and activation energy. This finding and application should be helpful in further study for the TCPO CL reaction, and revealed an attractive opportunity for simplifying the CE-CL system, such as in a microchip device. Copyright © 2011 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

A simple and sensitive method for determination of free amino acids in milk by microchip electrophoresis (MCE) coupled with laser-induced fluorescence (LIF) detection was developed. Seven kinds of standard amino acids were derivated with sulfoindocyanine succinimidyl ester (Cy5) and then perfectly measured by MCE-LIF within 150 s. The parameters of MCE separation were carefully investigated to obtain the optimal conditions: 100 mmol·L−1 sodium borate solution (pH 10.0) as running buffer solution, 0.8 kV as injection voltage, 2.2 kV as separation voltage etc. The linear range of the detection of amino acids was from 0.01 µmol·L−1 to 1.0 µmol·L−1 and the detection limit was as low as about 1.0 nmol·L−1. This MCE-LIF method was applied to the measurements of free amino acids in actual milk samples and satisfactory experimental results were achieved. [ABSTRACT FROM AUTHOR]

A sensitive, simple and rapid flow-injection chemiluminescence (FI-CL) method is described to determine tsumacide pesticide residue based on the CL reaction of the alkaline degradation product of tsumacide with acidic KMnO4 when rhodamine 6G was present. Under the optimum conditions, the relative CL intensity is linear with the concentration of tsumacide in the range of 2.0 × 10−3-0.20 mg/L. The detection limit is 6.6 × 10−4 mg/L (3 σ) and the relative standard deviation for 2.0 × 10−2 mg/L tsumacide solution was 2.28% (intra-day) and 4.85% (inter-day). The proposed method has been applied to determine the residue of tsumacide in vegetable samples and the recovery test is very satisfactory. Copyright © 2007 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

On page 8960, C. L. Chen, J. J. De Yoreo, and co‐workers explore the ability of 2D membrane‐like materials, which self‐assemble from amphiphilic peptoids, to self‐repair after damage under a range of solution and surface conditions. They then exploit this ability to form nm‐scale patterns of distinct functional groups within a single coherent membrane. [ABSTRACT FROM AUTHOR]