Au nanoparticle-modified hollow carbon spheres as an advanced electrochemical sensing platform for effective detection of homocysteine in human serum.

It is widely known that homocysteine (Hcy) is associated with the pathogenesis of many clinical diseases, and its quantitative detection can help early treatment of related diseases. The selection of materials with excellent properties is important for the construction of electrochemical sensing platforms and quantitative detection of Hcy. In this study, two nanocomposites, Au nanoparticles/hollow carbon spheres (AuNPs@HCS) and Au nanoparticles/solid carbon spheres (AuNPs@SCS), were prepared first.

Adjustable chromatographic performance of silica-based mixed-mode stationary phase through the control of co-grafting amounts of imidazole and C18 chain.

In this paper, three imidazole- and C18- bifunctional silica stationary phases (Sil-Im-C18) were prepared by adjusting introduction interval of octadecyltrichlorosilane (ODS) and 3-imidazol-1-ylpropyl(trimethoxy)silane (TMPImS), which can be used for reversed-phase liquid chromatography (RPLC) and ion exchange chromatography (IEC) with adjustable performance. The successful preparation of Sil-Im-C18 were confirmed by the characterizations of elemental analysis, infrared spectroscopy (FTIR) and contact angle (CA). Chromatographic performance of Sil-Im-C18 were evaluated by the separation of Tanaka test mixture, alkylbenzenes, linear PAHs and a set of analytes with different properties (uracil, phenol, 1,2-dinitrobenzene and naphthalene), and compared with commonly used C18 column.

A C4-modified bipyridinium multi-mode stationary phase for reversed phase, hydrophilic interaction and ion exchange chromatography.

A novel C4-modified bipyridinium stationary phase (Sil-DPC4) was prepared and characterized by elemental analysis (EA) and Fourier transform infrared spectrometry (FT-IR) and further investigated for multi-mode liquid chromatography. The chromatographic performances of Sil-DPC4 were evaluated by reversed-phase chromatography using polycyclic aromatic hydrocarbons (PAHs), phenylamines and phenols, hydrophilic interaction chromatography using nucleosides and nucleobases, and ion exchange chromatography using inorganic ions and organic ions. The effects of the acetonitrile content, salt concentration and pH value of the mobile phase on the retention of Sil-DPC4 were also investigated.

Grafting of Tetraphenylethylene on Silica Surface, Characterizations, and Their Chromatographic Performance as Reversed-Phase Stationary Phases.

Surface modification is an effective way to functionalize the materials so as to get some special properties. Tetraphenylethylene (TPE) has been widely investigated as a well-known reagent which has the nature of aggregation-induced emission (AIE), but has never been reported in the liquid chromatography stationary phase. In this work, TPE-grafted silica (Sil-TPE) was obtained successfully using the derivative of 1-(4-hydroxyphenyl)-1,2,2-triphenylethylene as a ligand, and then characterized by elemental analysis, Fourier transform infrared spectra, thermogravimetric analysis, and so forth.

Correction: A novel electrochemical sensor based on microporous polymeric nanospheres for measuring peroxynitrite anion released by living cells and studying the synergistic effect of antioxidants.

Correction for 'A novel electrochemical sensor based on microporous polymeric nanospheres for measuring peroxynitrite anion released by living cells and studying the synergistic effect of antioxidants' by Fuxin Liu , , 2019, , 6905-6913, https://doi.org/10.1039/C9AN01693G.

Construction of a novel electrochemical sensing platform to investigate the effect of temperature on superoxide anions from cells and superoxide dismutase enzyme activity.

It is of great significance to realize the detection of trace amounts of superoxide anions (O•) in biological systems due to the connection between the concentration of O• and some diseases. Here, we present a novel method to fabricate a non-enzymatic electrochemical sensor for measuring O• from biological systems. The sensor was fabricated by nanocomposites (PAMAM-Au) synthesized by using (PAMAM-G4.

Photothermometric analysis of bismuth ions using aggregation-induced nanozyme system with a target-triggered surface cleaning effect.

The development of nanozyme-based photothermometric sensing for point-of-care testing (POCT) heavy metal ions is of great significance for disease diagnosis and health management. Considering the low catalytic activity of most nanozymes at physiological pH, we found bismuth ions (Bi) could effectively enhance the peroxidase (POX)-like activity of cetyltrimethylammonium bromide and citrate-capped octahedral gold nanoparticle (CTAB/Cit-AuNP) nanozymes. It is mainly based on Biions being able to trigger the surface cleaning effect of CTAB/Cit-AuNPs.

A Fenton-like reaction system with analyte-activated catfish effect as an enhanced colorimetric and photothermal dopamine bioassay.

Fenton-like reaction systems have been proven to be efficient as powerful promoters in advanced oxidation processes (AOPs) due to their generated reactive oxygen species (ROS), such as ˙OH and ˙O, which can further oxidize a specific chromogenic substrate like 3,3',5,5'-tetramethylbenzidine (TMB) to generate sensitive color readout and thereby demonstrate more potential in the colorimetric analysis field. However, the inherent drawback of the low rate-limiting step of Fe/Fe conversion in the Fenton-like reaction and its resultant inefficiency for HO decomposition hinder its practical applications. We herein communicate an analyte-activated catfish effect based catalysis strategy to promote the Fenton-like reaction, in which dopamine, like a catfish, was added to activate the Fenton-like reaction.

Highly Selective Separation of Rare Earth Elements by Zn-BTC Metal-Organic Framework/Nanoporous Graphene Green Synthesis.

Rare earth elements (REEs) are used widely in devices of many fields, but it is still a troublesome task to achieve their selective separation and purification. Metal-organic frameworks (MOFs) as an emerging porous crystalline material have been used for selective separation of REEs using the size-selective crystallization properties. However, so far, almost all MOFs cannot be used directly for selective separation of REEs in strong acid solid-state adsorption.

Simply translating mercury detection into a temperature measurement: using an aggregation-activated oxidase-like activity of gold nanoparticles.

A novel Hg-responsive thermometer system for translating mercury detection into temperature monitoring was developed based on an aggregation-activated oxidase-like activity of gold nanoparticles.

Gold nanozyme as an excellent co-catalyst for enhancing the performance of a colorimetric and photothermal bioassay.

Advanced oxidation processes (AOPs) have recently proposed for advancing colorimetric sensing applications, owing to their excellent performance of sensitive color readout that generated from the oxidation of chromogenic substrates like 3,3',5,5'-tetramethylbenzidine (TMB) by reactive oxygen species (ROS) of AOPs such as ·OH and ·O radicals. However, the efficiency of ROS generation and the related HO decomposition in most AOPs is quite low especially at neutral pH, which greatly hampered the practical sensing applications of the AOPs. We herein communicated that β-cyclodextrin (β-CD)-capped gold nanoparticles (β-CD@AuNPs) can promote catalysis at neutral pH for AOP as an excellent co-catalyst.

Photothermal and colorimetric dual mode detection of nanomolar ferric ions in environmental sample based on in situ generation of prussian blue nanoparticles.

Iron ions play a key role in many physiological processes, which can provide feedback for the evaluation of biological systems and environmental processes. New strategies for portable determination of Fe therefore are still in urgent need. Here, through an in situ generation of prussian blue nanoparticles (PB NPs) in aqueous solution, we developed a bimodal method for photothermal and colorimetric detection of Fe.

Target-mediated surface chemistry of gold nanorods for breaking the low color resolution limitation of monocolorimetric sensor.

A long-term limitation of low color resolution in the monocolorimetric sensors seriously restricts its extending application, especially for the traditional organic dyes-based monocolorimetric sensors. Herein, we explore a simple target-mediated surface chemistry-based modulation for regulating the surface of gold nanorods (AuNRs), resulting in a successful multicolorimetric sensor for inorganic pyrophosphatase (PPase) activity. It operates on the principle that PPase modulates the release of Fe free from the ferric-pyrophosphate complex (Fe-PPi) through a specific target-catalyzed hydrolysis process, leading to a better mediation for the unique chemical redox reaction between Fe and I.

Molecule-gated surface chemistry of Pt nanoparticles for constructing activity-controllable nanozymes and a three-in-one sensor.

Herein, a simple strategy for constructing activity-controllable nanozymes is proposed based on the glutathione (GSH)-gated surface chemistry of citrate-capped Pt nanoparticles (PtNPs). PtNPs have been shown to have oxidase-like activity that can effectively catalyze the oxidation of 3,3',5,5'-tertamethylbenzidine (TMB) by O2, resulting in a typical color reaction from colorless to blue. We found that GSH can inhibit the oxidase-like activity of PtNPs as a molecule-gated surface chemistry element, resulting in a dramatic decrease of the oxidation of TMB.

A novel electrochemical sensor based on microporous polymeric nanospheres for measuring peroxynitrite anion released by living cells and studying the synergistic effect of antioxidants.

Peroxynitrite anion (ONOO-) is a crucial reactive nitrogen species (RNS), which has aroused immense research interest in the biological and biomedical fields because aberrant expression levels of ONOO- are related to many diseases. In this work, a novel electrochemical sensor is described for the detection of peroxynitrite anion (ONOO-) released from living cells. It is constructed with a glassy carbon electrode (GCE) decorated with a nanocomposite (CTS-MPNS) synthesized from chitosan (CTS) functionalized microporous polymeric nanospheres (MPNS).

Resistance and clonal selection among Allium sativum L. germplasm resources to Delia antiqua M. and its correlation with allicin content.

Background: Garlic is the second largest allium crop after onion and is grown all over the world. The onion maggot (Delia antiqua M.) is a pest that seriously affects the yield and quality of garlic.

An ultrasensitive electrochemical sensor based on cotton carbon fiber composites for the determination of superoxide anion release from cells.

A sensor is described for determination of superoxide anion (O˙). The electrode consists of nitrogen-doped cotton carbon fiber (NCFs) modified with silver nanoparticles (AgNPs) which have excellent catalytic capability. The resulting sensor, best operated at working potentials around -0.

Metal-organic framework derived carbon-based sensor for monitoring of the oxidative stress of living cell and assessment of antioxidant activity of food extracts.

A novel non-enzymatic superoxide anion radical (O) sensor was prepared by silver nanoparticles (AgNPs) decorated organic frameworks (MOFs) compound-derived metal oxide coated carbon material. Transmission electron microscopy (TEM) was employed to characterize morphologies and structures of the as-prepared samples AgNPs/CoO@C. Electrochemical studies indicated that the AgNPs/CoO@C/GCE exhibited excellent detection ability to O.

A sensitively non-enzymatic amperometric sensor and its application in living cell superoxide anion radical detection.

Here, we report a nanocomposite composed of silver nanoparticles and multi-walled carbon nanotubes (AgNPs/MWNTs) utilized as an efficient electrode material for sensitive detection superoxide anion (O). The procedure to synthesize AgNPs/MWNTs nanocomposites was green and facile. In the presence of functionalized multi-wall carbon nanotubes (MWNTs), silver nanoparticles (AgNPs) were in situ generated by chemical reduction of silver nitrate with glucose as a reducing and stabilizing agent to give the desired AgNPs/MWNTs nanocomposites.

Construction of an ultrasensitive non-enzymatic sensor to investigate the dynamic process of superoxide anion release from living cells.

In this work, a novel non-enzymatic superoxide anion (O•) sensor was constructed based on Ag nanoparticles (NPs) / poly (amidoamine) (PAMAM) dendrimers and used to investigate the dynamic process of O• release from living cells. The AgNPs/PAMAM nanohybrids were characterized by transmission electron microscopy (TEM), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The fabricated electrode exhibited excellent catalytic activity toward the reaction of O• with a super low detection limit (LOD) of 2.

A colorimetric indicator-displacement assay for cysteine sensing based on a molecule-exchange mechanism.

In this study, we developed an ingenious yet effective strategy for cysteine detection. The colorimetric cysteine assay is established through an indicator displacement process, where Cu and pyrocatechol violet (PV) was employed as receptor and indicator, respectively. Proof-of-concept trials demonstrated that the stronger binding affinity of Cu receptor toward cysteine than PV indicator endowed our colorimetric sensor with high selectivity and excellent sensitivity as well as with a lower detection limit (4.

A colorimetric sensor of cysteine based on self-assembly nanostructures of Fe-HO/Tetramethylbenzidine system with "On-Off" switching function.

Many strategies have been explored for selectively and sensitively detecting cysteine in different samples. Here, a novel colorimetric sensor based on self-assembly nanostructures of Fe-HO/Tetramethylbenzidine system with dual-level logic gate function and colorimetric determination of cysteine were firstly explored. The proposed Fe-HO-TMB system provides a sensitive optical signal due to the selectively reductive ability of cysteine to the oxidized TMB and thus could be successfully applied to the construction of instant on-site visual detection method with a paper based test strip for cysteine determination in a sample solution as well as for a dual-level logic gate fabrication.