A target-triggered fluorescence-SERS dual-signal nano-system for real-time imaging of intracellular telomerase activity.

Telomerase (TE) is a promising diagnostic and prognostic biomarker for many cancers. Quantification of TE activity in living cells is of great significance in biomedical and clinical research. Conventional fluorescence-based sensors for quantification of intracellular TE may suffer from problems of fast photobleaching and auto-fluorescence of some endogenous molecules, and hence are liable to produce false negative or positive results.

Telomerase-initiated three-dimensional DNAzyme motor for monitoring of telomerase activity in living cells.

Telomerase (TE) is recognized as a potential biomarker for early diagnosis, monitoring and treatment of cancer. At present, most of the methods for TE detection are only applicable to in vitro assays, and unsuitable for in vivo applications. Though a few intracellular probes have been reported to have good specificity for TE, they do not involve signal amplification, which hinders their applicability in scenarios requiring high sensitivity.

Calibration model transfer in mid-infrared process analysis with attenuated total reflectance immersion probes.

Process applications of mid-infrared (MIR) spectrometry may involve replacement of the spectrometer and/or measurement probe, which generally requires a calibration transfer method to maintain the accuracy of analysis. In this study, direct standardisation (DS), piecewise direct standardisation (PDS) and spectral space transformation (SST) were compared for analysis of ternary mixtures of acetone, ethanol and ethyl acetate. Three calibration transfer examples were considered: changing the spectrometer, multiplexing two probes to a spectrometer, and changing the diameter of the attenuated total reflectance (ATR) probe (as might be required when scaling up from lab to process analysis).

Label-free and sensitive microRNA detection method based on the locked nucleic acid assisted fishing amplification strategy.

Herein, a label free and sensitive miRNA detection method with enhanced practical applicability was developed based on the locked nucleic acid (LNA) assisted repeated fishing amplification strategy. The working mechanism of the proposed method is as follows: 1) a DNA probe (i.e, L-DNA) with LNA bases is immobilized onto the surface of a gold foil.

The combined toxicity and mechanism of multi-walled carbon nanotubes and nano zinc oxide toward the cabbage.

The natural environment is a complex system, and there is never only one kind of nanomaterial entering the environment. However, many studies only considered the plant toxicity of one kind of nanomaterial and do not consider the influence of two or more kinds of nanomaterials on plant toxicity. Multi-walled carbon nanotubes (MWCNTs) and zinc oxide nanoparticles (ZnO NPs) are two common and widely used nanomaterials in water environment, so these two kinds of nanomaterials were chosen to explore the effects of their combined toxicity on cabbage.

Label-free microRNA detection through analyzing the length distribution pattern of the residual fragments of probe DNA produced during exonuclease III assisted signal amplification by mass spectrometry.

Biosensors based on various spectroscopic techniques discriminate the target microRNA (miRNA) from non-target ones with single nucleotide polymorphisms (SNPs) according to the differences in signal intensities which can be caused by other factors besides SNPs. As a result, they are liable to produce false positive results. Herein, we report an attempt to develop a false-positive resistance, sensitive and reliable mass spectrometric platform for miRNA detection.

Ultrasensitive detection of protein biomarkers by MALDI-TOF mass spectrometry based on ZnFeO nanoparticles and mass tagging signal amplification.

A facile MALDI-TOF mass spectrometric platform for quantitative analysis of protein biomarkers was developed based on magnetic ZnFeO nanoparticles and mass tagging signal amplification. In this platform, magnetic ZnFeO nanoparticles functionalized with an aptamer of the biomarker of interest was used to magnetically separate silica nanoparticles modified with another aptamer of the target biomarker and a barcoding peptide from solution phase in the presence of the biomarker of interest. After the silica nanoparticles were dissolved by KHF, the released barcoding peptide was detected by MALDI-TOF mass spectrometry with magnetic ZnFeO nanoparticles used as assisting matrix of laser desorption ionization.

A Review of Carbon Dots Produced from Biomass Wastes.

The fluorescent carbon dot is a novel type of carbon nanomaterial. In comparison with semiconductor quantum dots and fluorescence organic agents, it possesses significant advantages such as excellent photostability and biocompatibility, low cytotoxicity and easy surface functionalization, which endow it a wide application prospect in fields of bioimaging, chemical sensing, environmental monitoring, disease diagnosis and photocatalysis as well. Biomass waste is a good choice for the production of carbon dots owing to its abundance, wide availability, eco-friendly nature and a source of low cost renewable raw materials such as cellulose, hemicellulose, lignin, carbohydrates and proteins, etc.

Detection of microRNAs by the combination of Exonuclease-III assisted target recycling amplification and repeated-fishing strategy.

A simple but effective method for the detection of miRNAs was proposed by integrating exonuclease-III assisted target recycling amplification and repeated-fishing strategy. In the proposed method, exonuclease-III assisted target recycling amplification reaction is adopted to produce a large amount of DNA fragments with fluorescence group at its 5' end in the presence of the target miRNA, which are then repeatedly fished out from the reaction mixture by a gold foil modified with a capture probe and transferred into a so-called 'product tube'. The amount of the target miRNA can then be determined from the fluorescence measurement of the solution in the 'product tube'.

An assumption-free quantitative polymerase chain reaction method with internal standard.

In real-time quantitative polymerase chain reaction (PCR), the standard curve between threshold cycle and logarithm of template concentration is currently the gold standard for template quantification. The efficacy of this approach is limited by the necessary assumption that all samples are amplified with the same efficiency. To overcome this limitation, a new method has been proposed in this contribution for quantitative PCR with internal standard.

A novel ratiometric fluorescent sensing method based on MnO nanosheet for sensitive detection of alkaline phosphatase in serum.

Alkaline phosphatase (ALP) is an important biomarker for clinical diagnosis. Abnormal levels of ALP are closely related to many diseases. In this contribution, a ratiometric fluorescent sensing method based on the competition between two oxidation-reduction reactions related to MnO nanosheets was developed for ALP detection.

Highly specific and sensitive detection of microRNAs by tandem signal amplification based on duplex-specific nuclease and strand displacement.

Based on the full understanding of the hydrolysis patterns of duplex-specific nuclease (DSN) against the probe DNAs in DNA/microRNA heteroduplexes, a simple and generic platform for highly specific and sensitive detection of microRNAs was developed by seamlessly integrating DSN-assisted target recycling amplification and strand displacement amplification in tandem.

Quantification of enantiomers by mass spectrometry based on chemical derivatization and spectral shape deformation quantitative theory.

A facile mass spectrometric kinetic method for quantitative analysis of chiral compounds was developed by integrating mass spectrometry based on chemical derivatization and the spectral shape deformation quantitative theory. Chemical derivatization was employed to introduce diastereomeric environments to the chiral compounds of interest, resulting in different abundance distribution patterns of fragment ions of the derivatization products of enantiomers in mass spectrometry. The quantitative information of the chiral compounds of interest was extracted from complex mass spectral data by an advanced calibration model derived based on the spectral shape deformation quantitative theory.

Label-Free and Multiplexed Quantification of microRNAs by Mass Spectrometry Based on Duplex-Specific-Nuclease-Assisted Recycling Amplification.

MicroRNAs (miRNAs) are important biomarker candidates for cancer screening and early detection research. Generally, miRNAs undergo synergistic adjustments in tumor cells. Herein, a mass-spectrometric method based on a duplex-specific-nuclease (DSN)-enzyme-assisted signal-amplification technique was proposed for label-free and multiplexed detection of multiple miRNAs, and applied to the quantification of three miRNAs (i.

Generalized ratiometric fluorescence nanosensors based on carbon dots and an advanced chemometric model.

Probe encapsulated by biologically localized embedding (PEBBLE) has emerged as a new type of sensing technique for complex systems. Generalized ratiometric PEBBLE nanosensors prepared by encapsulating an intensity-based probe and an inert reference dye inside the pores of stable matrix possess advantages of easy synthesis, immunity to interference, lower toxicity, and robustness to variations in probe loading. However, the selection of appropriate reference dyes used in generalized ratiometric PEBBLE nanosensors is a rather difficult task since they should satisfy some stringent requirements.

Quantification of Cadmium in Rice by Surface-enhanced Raman Spectroscopy Based on a Ratiometric Indicator and Conical Holed Enhancing Substrates.

A surface-enhanced Raman spectroscopy (SERS) based method was developed for the quantification of Cd in rice. Gold nano-particles (AuNPs) modified with trimercaptotriazine served as a ratiometric SERS probe for the detection of Cd. A conical holed substrate was used to further enhance SERS signals, and hence to improve the sensitivity.

A novel calibration strategy based on background correction for quantitative circular dichroism spectroscopy.

When using circular dichroism (CD) spectroscopy for quantitative analysis, the samples to be analyzed must be free of light-absorbing interferences. However, in real-world samples, the presence of background absorbers is practically unavoidable. The difference in the matrices between the real-world samples to be analyzed and the standard samples (on which either univariate or multivariate calibration model was built) would result in systematic errors in the quantification results of CD spectroscopy.

Quantitative generalized ratiometric fluorescence spectroscopy for turbid media based on probe encapsulated by biologically localized embedding.

PEBBLE (probe encapsulated by biologically localized embedding) nanosensor encapsulating an intensity-based fluorescence indicator and an inert reference fluorescence dye inside the pores of stable matrix can be used as a generalized wavelength-ratiometric probe. However, the lack of an efficient quantitative model render the choices of inert reference dyes and intensity-based fluorescence indicators used in PEBBLEs based generalized wavelength-ratiometric probes rather limited. In this contribution, an extended quantitative fluorescence model was derived specifically for generalized wavelength-ratiometric probes based on PEBBLE technique (QFMGRP) with a view to simplify the design of PEBBLEs and hence further extend their application potentials.

Generalized multiple internal standard method for quantitative liquid chromatography mass spectrometry.

In this contribution, a multiplicative effects model for generalized multiple-internal-standard method (MEMGMIS) was proposed to solve the signal instability problem of LC-MS over time. MEMGMIS model seamlessly integrates the multiple-internal-standard strategy with multivariate calibration method, and takes full use of all the information carried by multiple internal standards during the quantification of target analytes. Unlike the existing methods based on multiple internal standards, MEMGMIS does not require selecting an optimal internal standard for the quantification of a specific analyte from multiple internal standards used.

Surface-enhanced Raman spectroscopy based on conical holed enhancing substrates.

In this contribution, surface-enhanced Raman spectroscopy (SERS) based on conical holed glass substrates deposited with silver colloids was reported for the first time. It combines the advantages of both dry SERS assays based on plane films deposited with silver colloids and wet SERS assays utilizing cuvettes or capillary tubes. Compared with plane glass substrates deposited with silver colloids, the conical holed glass substrates deposited with silver colloids exhibited five-to ten-folds of increase in the rate of signal enhancement, due to the internal multiple reflections of both the excitation laser beam and the Raman scattering photons within conical holes.

Generalized ratiometric indicator based surface-enhanced Raman spectroscopy for the detection of Cd(2+) in environmental water samples.

The concept of generalized ratiometric indicator based surface-enhanced Raman spectroscopy was first introduced and successfully implemented in the detection of Cd(2+) in environmental water samples using Au nanoparticles (AuNPs) modified by trithiocyanuric acid (TMT). Without the use of any internal standard, the proposed method achieved accurate concentration predictions for Cd(2+) in environmental water samples with recoveries in the ranges of 91.8-108.

Multiplicative effects model with internal standard in mobile phase for quantitative liquid chromatography-mass spectrometry.

Liquid chromatography-mass spectrometry assays suffer from signal instability caused by the gradual fouling of the ion source, vacuum instability, aging of the ion multiplier, etc. To address this issue, in this contribution, an internal standard was added into the mobile phase. The internal standard was therefore ionized and detected together with the analytes of interest by the mass spectrometer to ensure that variations in measurement conditions and/or instrument have similar effects on the signal contributions of both the analytes of interest and the internal standard.

Novel calibration model maintenance strategy for solving the signal instability in quantitative liquid chromatography-mass spectrometry.

In this contribution, a multiplicative effects model with a parameter accounting for the variations in overall sensitivity over time was proposed to reduce the effects of signal instability on quantitative results of LC-MS/MS. This method allows the use of calibration models constructed from large standard sets without having to repeat their measurement even though variations occur in sensitivity and baseline signal intensity. The performance of the proposed method was tested on two proof-of-concept model systems: the determination of the target peptide in two sets of peptide digests mixtures and the quantification of melamine and metronidazole in two sets of milk powder samples.