An efficient PCN-224/graphene aerogel-based extraction method for monitoring the degradation of organophosphorus pesticides in juice.

An efficient PCN-224/graphene aerogel modified silica (PCN-224/GA@Sil)-based extraction method was established for monitoring the degradation process of two organophosphorus pesticides (OPPs) in juice. PCN-224/GA@Sil exhibited higher surface area (307.35 m g) than graphene oxide modified silica (254.

A covalent-organic framework-based platform for simultaneous smartphone detection and degradation of aflatoxin B1.

This study developed a smartphone-based biosensor that could simultaneously detect and degrade aflatoxin B1 (AFB1). A donor-acceptor covalent organic framework (COF) was bound onto the surface of stainless-steel mesh (SSM) via the in-situ synthesis, which was used to immobilize the aptamer (Apt) to specifically capture AFB1 and was also as a photocatalyst to degrade AFB1. Au@Ir nanospheres were synthesized, which exhibited better peroxidase catalytic activity (K=5.

Poly (ionic liquid) cross-linked hydrogel encapsulated with AuPt nanozymes for the smartphone-based colorimetric detection of zearalenone.

A poly (ionic liquid) enhanced poly(acrylamide-acrylic acid) (PIL-PAM/AA) hydrogel-based colorimetric sensor was designed to detect zearalenone (ZEN). Different AuPt nanoparticles were synthesized via the on-pot method. Through the kinetic analysis and the theoretical calculation, AuPt possessed the relatively low energy barriers to adsorb and decompose HO so that it exhibited relatively better catalytic activity (K = 2.

Ionic liquid-enhanced silica aerogels for the specific extraction and detection of aflatoxin B1 coupled with a smartphone-based colorimetric biosensor.

The polymer ionic liquid (1-allyl-3-butylimidazolium bromide) enhanced silica aerogel was modified onto the surface of stainless-steel mesh to immobilize aptamer-1 for the specific recognition of AFB1. The porous channels of silica aerogel could prevent the interference of macromolecules in food samples. Enzyme kinetic analysis showed that the MoS/Au was an effective peroxidase mimic with a relatively low Michaelis constant (K) value of 0.

Ionic liquids functionalized FeO-based colorimetric biosensor for rapid determination of ochratoxin A.

A stainless steel mesh (SSM) with the feature of flexibility was employed as the colorimetric biosensor substrate, and aptamer was bond onto the surface of the SSM. Through the cross-linking of ionic liquids (ILs), AuPt nanoparticles were deposited  onto the surface of FeO material to obtain a magnetic nanozyme with high peroxidase catalytic activity and rapid color change. Through the competing interaction of OTA and cDNA with aptamer, AuPt@IL@FeO signal probe was separated to catalyze the 3,3',5,5'-tetramethylbenzidine/hydrogen peroxide (TMB/HO) system to observe the color by bare eye and record the absorbance at 652 nm using a UV-spectrophotometer.

Integration of Metallic Nanomaterials and Recognition Elements for the Specifically Monitoring of Pesticides in Electrochemical Sensing.

Although all countries have been controlling the excessive use of pesticides, incidents of pesticide residues still existed. Electrochemical biosensors are extensively applied detection techniques to monitor pesticides with the help of different types of biorecognition components mainly including, antibodies, aptamers, enzymes (i.e.

Hydrophilic Covalent Organic Frameworks Coated Steel Sheet As a Mass Spectrometric Ionization Source for the Direct Determination of Zearalenone and Its Derivatives.

Zearalenone has attracted worldwide attention due to its toxic properties and threat to public health. A rapid determination method for zearalenone and its derivatives by hydrophilic covalent organic frameworks coated steel sheet (HCOFCS) combined with ambient mass spectrometry (AMS) was developed. The HCOFCS behaved as both a tip for solid-phase microextraction and a solid substrate for electrospray ionization mass spectrometry (ESI-MS).

An aptamer and flower-shaped AuPtRh nanoenzyme-based colorimetric biosensor for the detection of profenofos.

In this work, a simple, sensitive and selective colorimetric method was established for the detection of profenofos. Firstly, novel flower-shaped AuPtRh trimetallic nanospheres were synthesized a simple one-pot method, and had outstanding peroxidase catalytic activity. AuPtRh nanospheres with a great specific surface area were linked with an aptamer Au-S and Pt-S bonds to specifically recognize profenofos.

Progress in Nanomaterials-Based Enzyme and Aptamer Biosensor for the Detection of Organophosphorus Pesticides.

With the improvement of people's safety awareness, the requirement of pesticide detection is gradually increasing, and many new detection methods toward Organophosphorus pesticide (OPs) has been further developed and applied. Nanomaterials-based biosensors have played an important role in the trace detection of OPs. This article mainly introduces the detection principle of enzymes and aptamers as the identification element of biosensors.

Electrochemical (Bio)Sensors for the Detection of Organophosphorus Pesticides Based on Nanomaterial-Modified Electrodes: A Review.

Organophosphorus pesticides were easily remained in fruits and vegetables which would be harm to the environmental safety and human health. In recent years, due to the simple preparation process, fast response and high sensitivity, the electrochemical (bio)sensors have received increasing attention, which were extensively used as the sensing platform for the detection of OPPs. The mechanisms for the determination of OPPs mainly included redox of nitrophenyl OPPs, enzyme hydrolysis and inhibition, immunosensor, aptasensor.

[Determination of organophosphorus pesticides based on graphene oxide aerogel solid phase extraction column].

A graphene oxide aerogel was prepared and directly filled in a solid phase extraction (SPE) column without the aid of silica or other substrates. The aerogel was used to extract and detect residual organophosphorus pesticides (phoxim, temephos, fenthion, and fenitrothion) in food, and exhibited good elasticity and high mechanical strength. The graphene oxide aerogel was prepared by freeze-drying.

Chiral carbon quantum dots as fluorescent probe for rapid chiral recognition of isoleucine enantiomers.

Chiral recognition is always a significant and challenging work in analytical chemistry. A fluorescent chiral recognition method based on chiral carbon quantum dots (CCQDs) towards isoleucine (Ile) enantiomers was developed in this work. CCQDs were synthesized by one-step hydrothermal method using l-cysteine as chiral source.

Synthesis of octadecylamine-derived carbon dots and application in reversed phase/hydrophilic interaction liquid chromatography.

In order to make up for the deficiencies of traditional C18 column for separating strong polar compounds, combined with the good hydrophilicity of carbon dots (CDs), novel octadecylamine-derived CDs denoted as C18-CDs are designed, synthesized and applied in RPLC/HILIC mixed-mode chromatography with good separation performance towards both hydrophobic and hydrophilic compounds. C18-CDs are synthesized by simple one-step solvothermal method using octadecylamine and citric acid as carbon sources, and C18-CDs with proper polarity are collected through column chromatography purification. This C18-CDs decorated silica column showed good separation performance for polycyclic aromatic hydrocarbons and alkylbenzenes under RPLC mode.

ZrO Nanoparticles and Poly(diallyldimethylammonium chloride)-Doped Graphene Oxide Aerogel-Coated Stainless-Steel Mesh for the Effective Adsorption of Organophosphorus Pesticides.

A novel sorbent based on the ZrO nanoparticles and poly(diallyldimethylammonium chloride)-modified graphene oxide aerogel-grafted stainless steel mesh (ZrO/PDDA-GOA-SSM) was used for the extraction and detection of organophosphorus pesticides (OPPs). Firstly, the PDDA and GO composite was grafted onto the surface of SSM and then freeze-dried to obtain the aerogel, which efficiently reduced the accumulation of graphene nanosheets. It integrated the advanced properties of GOA with a thin coating and the three-dimensional structural geometry of SSM.

Amphipathic carbon quantum dots-functionalized silica stationary phase for reversed phase/hydrophilic interaction chromatography.

Carbon quantum dots (CQDs) are considered as good chromatographic separation materials. However, due to the hydrophily of the synthesized CQDs, their applications in HPLC are limited to HILIC for separating strong polar compounds only. In this work, a novel amphipathic CQDs with both hydrophobicity and hydrophily is developed as mixed-mode stationary phase for RPLC/HILIC.

Construction of an electrochemical sensor with graphene aerogel doped with ZrO nanoparticles and chitosan for the selective detection of luteolin.

A simple, fast and sensitive method for the detection of luteolin is proposed based on the chitosan/reduced graphene oxide aerogel with dispersed ZrO nanoparticles modified glassy carbon electrode (ZrO/CS/rGOA-GCE) as an electrochemical sensor. The ZrO/CS/rGOA composite was prepared by one pot synthesis from a mixture of GO, CS and zirconyl chloride octahydrate, and subsequently be freeze-dried. Scanning electron microscope images showed a typical thin, wrinkled and fluctuant morphology of graphene nanosheets and the polymerized CS and ZrO nanoparticles deposited on the surface of rGOA.

Cationic polyelectrolyte/graphene oxide as an efficient sorbent for the extraction and analysis of trace acidic herbicides in vegetables.

The facile preparation and characterization of a cationic polyelectrolyte (polydiallyldimethylammonium chloride, PDDA) fabricated graphene oxide-grafted silica microsphere (PDDA@GO@Sil) with high positive charge density as the sorbent for the high selective capture of acidic herbicides were reported. The theoretical calculation showed that there were strong adsorption energies between the PDDA and analytes, and the main interaction was the hydrogen bonding from OH…Cl and CO…HC. Static- and dynamic- state adsorption results indicated that acidic herbicides were the monolayer coverage onto the PDDA@GO@Sil due to the electrostatic attraction between the sorbent and analytes, and electrostatic repulsion among analytes.

A porous polyaniline nanotube sorbent for solid-phase extraction of the fluorescent reaction product of reactive oxygen species in cells, and its determination by HPLC.

A method is described for extracting and detecting the fluorescent reaction product (2',7'-dichlorofluorescein, DCF) that is formed by reaction of reactive oxygen species (ROS) with dichlorodihydrofluorescein diacetate (DCFH-DA). DCF is extracted by using porous polyaniline nanotubes (PPN) which have a large specific surface and pore volume which favor the adsorption capacity. Additional attractive features include an appropriate pore size distribution, hydrophobic surface, and electron-attracting groups which contribute to DCF adsorption.

Preparation and application of guanidyl-functionalized graphene oxide-grafted silica for efficient extraction of acidic herbicides by Box-Behnken design.

A highly selective and efficient extraction material was synthesized through the functionalization of guanidyl onto the graphene oxide-grafted silica via a simple chemical modification, which was designed and proposed to improve the enrichment capacity for acidic herbicides. The extraction material was confirmed by scanning electron microscopy, Fourier transform infrared spectrometry, X-ray photoelectron spectrometry, thermal gravimetric analyzer and zeta potential analysis. Theoretical adsorption energies, static- and dynamic-state binding experiments, and comparative experiments with various adsorbents were investigated to elucidate the adsorption mechanism.

β-Cyclodextrin-modified three-dimensional graphene oxide-wrapped melamine foam for the solid-phase extraction of flavonoids.

A new three-dimensional graphene oxide-wrapped melamine foam was prepared and used as a solid-phase extraction substrate. β-Cyclodextrin was fabricated onto the surface of three-dimensional graphene oxide-wrapped melamine foam by a chemical covalent interaction. In view of a specific surface area and a large delocalized π electron system of graphene oxide, in combination with a hydrophobic interior cavity and a hydrophilic peripheral face of β-cyclodextrin, the prepared extraction material was proposed for the determination of flavonoids.

Graphene oxide reinforced ionic liquid-functionalized adsorbent for solid-phase extraction of phenolic acids.

An environmental friendly sorbent of polymeric ionic liquids modified graphene oxide-grafted silica (PILs@GO@Sil) was synthesized for solid-phase extraction (SPE) of phenolic acids. The sorbent was prepared via a chemical layer-to-layer fabrication including amidation reaction, surface radical chain-transfer polymerization and in situ anion exchange. After modification with PILs, the silica surface had higher positive potential so that it would exhibit stronger electrostatic interaction for acidic compounds compared with GO@Sil.

Zinc oxide crystal whiskers as a novel sorbent for solid-phase extraction of flavonoids.

As a novel solid-phase extraction material, zinc oxide crystal whiskers were used to extract flavonoid compounds and showed good extraction abilities. X-ray diffraction, scanning electron microscopy with energy dispersive X-ray spectroscopy and surface area/pore volume characterized the sorbent. The zinc oxide was packed into a solid-phase extraction micro-column and its extraction ability was evaluated by four model flavonoid compounds.

Graphene oxide for solid-phase extraction of bioactive phenolic acids.

A solid-phase extraction (SPE) method for the efficient analysis of trace phenolic acids (PAs, caffeic acid, ferulic acid, protocatechuic acid, cinnamic acid) in urine was established. In this work, a graphene oxide (GO) coating was grafted onto pure silica to be investigated as SPE material. The prepared GO surface had a layered and wrinkled structure that was rough and well organized, which could provide more open adsorption sites.

Zinc sulfide nanosheets as a novel solid-phase extraction material for flavonoids.

As a novel solid-phase extraction material, zinc sulfide nanosheets were prepared by a simple method and were used to extract flavonoids. We used scanning electron microscopy to show its nanosheet morphology and energy dispersive X-ray spectroscopy and powder X-ray diffraction to confirm its chemical and phase compositions. Coupled to a high-performance liquid chromatography, the zinc sulfide nanosheets were packed into a microcolumn and were used to extract four model flavonoids to examine their extraction ability.

Polymeric ionic liquid modified graphene oxide-grafted silica for solid-phase extraction to analyze the excretion-dynamics of flavonoids in urine by Box-Behnken statistical design.

A solid-phase extraction method for the efficient analysis of the excretion-dynamics of flavonoids in urine was established and described. In this work, in situ surface radical chain-transfer polymerization and in situ anion exchange were utilized to tune the extraction performance of poly(1-vinyl-3-hexylimidazolium bromide)-graphene oxide-grafted silica (poly(VHIm(+)Br(-))@GO@Sil). Graphene oxide (GO) was first coated onto the silica using a layer-by-layer fabrication method, and then the anion of poly(VHIm(+)Br(-))@GO@Sil was changed into hexafluorophosphate (PF6(-)) by in situ anion exchange.