Poly(glycidyl methacrylate-co-N-methylolacrylamide-co-ethylene dimethacrylate) monolith coupled to high-performance liquid chromatography for the determination of adenosine phosphates in royal jelly

MoS2 quantum dots as a unique fluorescent "turn-off-on" probe for the simple and rapid determination of adenosine triphosphate

We report a one-step hydrothermal method for the preparation of fluorescent molybdenum disulfide quantum dots (MoS₂ QDs) and demonstrate the feasibility of fluorescent "turn-off-on" sensing of adenosine triphosphate (ATP) by using the MoS₂ QDs. MoS₂ QDs having strong blue-green fluorescence at 506 nm and good water-solubility were successfully synthesized by using ammonium tetrathiomolybdate as a single precursor. The fluorescence of MoS₂ QDs was first quenched by Fe³⁺ through the formation of a MoS₂ QDs/Fe³⁺ complex. ATP with the ability to coordinate with Fe³⁺ caused the dissociation of MoS₂ QDs/Fe³⁺, resulting in the final release of MoS₂ QDs and the recovery of fluorescence through a one-step competitive chelating process that took only 10 min to reach equilibrium at room temperature (RT). Facile and rapid sensing of Fe³⁺ and ATP could thus be achieved through the fluorescent "turn-off-on" strategy. Good linear relationships were obtained over the concentration ranges of 0-200 μM for Fe³⁺ and 0-140 μM for ATP with a lowest detectable concentration of 5 μM for ATP. Satisfactory results were obtained when the method was applied to a standard addition recovery trial of ATP in human serum samples. No complex surface modification during the preparation or detection process was needed based on the fluorescent "turn-off-on" method of the MoS₂ QDs, which suggests its great potential in fluorescent sensing.

Preparation of polymethacrylate monolith modified with cysteine for the determination of Cr(iii) ions

In this study, a simple and rapid polymer monolith microextraction procedure was developed for the determination of Cr(iii) ions by inductively coupled plasma-atomic emission spectrometry. A monolithic column modified with cysteine was synthesized and characterized by scanning electron microscopy, Fourier-transform infrared spectroscopy, X-ray photoelectron spectroscopy, thermal gravimetric analysis, specific surface area analysis and pore size distribution analysis. The influences of analytical parameters such as sample pH, adsorption time, eluent type, and coexisting ions were examined. The limit of detection (LOD) and limit of quantification (LOQ) for Cr(iii) ions were 0.005 μg mL-1 and 0.017 μg mL-1, and the relative standard deviation (RSD) was 7.4% (n = 5). The prepared cysteine functionalized monolithic column displayed good enrichment capacity and was successfully applied to the determination of Cr(iii) ions in real samples.

New detection method for nucleoside triphosphates based on carbon dots: The distance-dependent singlet oxygen trapping

The distance-dependent based sensing mechanism, such as fluorescence resonance energy transfer (FRET) and surface plasmon resonance (SPR) absorption of gold nanoparticles, has been used widely in visual detection. In this work, we report another distance-dependent detection method for nucleoside triphosphates (NTPs) based on carbon dots (CDs) (¹O₂ donor) and 9, 10-diphenylanthracene-2-boronic acid (DABA, ¹O₂ acceptor). The CDs can generate singlet oxygen (¹O₂) which allows diffusion within 200 nm. Thus, the distance between CDs and DABA decreased through binding of NTPs (<200 nm), leading to absorption changes of DABA under light irradiation due to ¹O₂ trapping. This sensing system (CDs@DABA) has high selectivity for the detection of NTPs due to the double molecular recognition and a linear response in the 0-80 μM concentration range was accomplished with the detection limit as low as 4.35 μM.

Antifouling aptasensor for the detection of adenosine triphosphate in biological media based on mixed self-assembled aptamer and zwitterionic peptide

Direct detection of targets in complex biological media with conventional biosensors is an enormous challenge due to the nonspecific adsorption and severe biofouling. In this work, a facile strategy for sensitive and low fouling detection of adenosine triphosphate (ATP) is developed through the construction of a mixed self-assembled biosensing interface, which was composed of zwitterionic peptide (antifouling material) and ATP aptamer (bio-recognition element). The peptide and aptamer (both containing thiol groups) were simultaneously self-assembled onto gold electrode surface electrodeposited with gold nanoparticles. The developed aptasensor possessed high selectivity and sensitivity for ATP, and it showed a wide linear response range towards ATP from 0.1pM to 5nM. Owing to the presence of peptide with excellent antifouling property in the biosensing interface, the aptasensor can detect ATP in complex biological media with remarkably reduced biofouling or nonspecific adsorption effect. Moreover, it can directly detect ATP in 1% human whole blood without suffering from any significant interference, indicating its great potential for practical assaying of ATP in biological samples.

Boronate-affinity hollow molecularly imprinted polymers for the selective extraction of nucleosides

Preparation of a boronate-affinity hollow molecularly imprinted polymer and its application as an SPE adsorbent for the selective enrichment of nucleosides.

Silica-particle-supported zwitterionic polymer monolith for microcolumn liquid chromatography

A silica-particle-supported zwitterionic polymeric monolithic column, shortened as supported column (S-column), was prepared by the in situ polymerization of methacrylic acid, ethylene dimethacrylate, and 2-(dimethylamino)ethyl methacrylate in the presence of a ternary porogenic solvent containing water, methanol, and cyclohexanol in a 250 μm id fused-silica capillary prepacked with 5 μm bare silica particles. In the S-column, a thin layer of the polymers was formed around the silica particles in the form of nanoglobules, leaving the interstitial spaces between the particles free for liquid flow. The effects of the preparation conditions on the morphology of the monolith were investigated by scanning electron microscopy and backpressure measurements. The selected volumetric ratio of porogens, monomer concentration, polymerization time, and temperature are 1:1:8 (water/methanol/cyclohexanol), 25% v/v, 5 h, and 60°C, respectively. The S-column was evaluated by comparison with its conventional organic counterpart in terms of morphology, mechanical stability, permeability, swelling-shrinking behavior, capacity, and efficiency. The results demonstrate that the S-column is superior to its counterpart in all the terms with the exception of permeability. The above merits and zwitterionic property of the S-column were further confirmed by separate separations of four inorganic anions and three organic cations.