Electrochemical sensor for bisphenol A based on a nanoporous polymerized ionic liquid interface

Concise Total Syntheses of Leuconoxine-Type Alkaloids Enabled by Palladium/Norbornene-Catalyzed Pyrrole Difunctionalization

Concise total syntheses of five leuconoxine-type alkaloids, i.e., chloromelodinine, leuconodine A, leuconodine F, melodinine E, and leuconoxine, are achieved through a pyrrole-centered strategy. The approach features a newly developed palladium/norbornene-catalyzed pyrrole double C─H functionalization reaction to generate the core skeleton and a divergent oxidative dearomatization to complete the end game. In addition, no protecting group was employed, and the strategic use of a chloro substituent offers a number of advantages in these syntheses, which could have implications beyond this work. The discovery of an unusual chloro 1,2-migration reaction enabled the first total synthesis of chloromelodinine E. This work represents the shortest syntheses of these natural products to date with 10-11 total steps.

Properties and Recent Advantages of N,N’-dialkylimidazolium-ion Liquids Application in Electrochemistry

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N,Nʹ-dialkylimidazolium-ion liquids is one of the important ionic liquids with a wide range of application as conductive electrolyte and in electrochemistry. The modified electrodes create a new view in fabrication of electroanalytical sensors. Many modifiers have beeen suggested for modification of electroanalytical sensor since many years ago. Over these years, ionic liquids and especially room temperature ionic liquids have attracted more attention due to their wide range of electrochemical windows and high electrical conductivity. N,Nʹ-dialkylimidazolium-ion liquids are one of the main important ionic liquids suggested for modification of bare electrodes and especially carbon paste electrodes. Although many review articles have reported onthe use of ionic liquids in electrochemical sensors, no review article has been specifically introduced so far on the review of the advantages of N,Nʹ-dialkylimidazolium ionic liquid. Therefore, in this review paper we focused on the introduction of recent advantages of N,Nʹ-dialkyl imidazolium ionic liquid in electrochemistry.

Advances in sensing and biosensing of bisphenols: A review

Bisphenols (BPs) are well known endocrine disrupting chemicals (EDCs) that cause adverse effects on the environment, biotic life and human health. BPs have been studied extensively because of an increasing concern for the safety of the environment and for human health. They are major raw materials for manufacturing polycarbonates, thermal papers and epoxy resins and are considered hazardous environmental contaminants. A vast array of sensors and biosensors have been developed for the sensitive screening of BPs based on carbon nanomaterials (carbon nanotubes, fullerenes, graphene and graphene oxide), quantum dots, metal and metal oxide nanocomposites, polymer nanocomposites, metal organic frameworks, ionic liquids and molecularly imprinted polymers. This review is devoted mainly to a variety of sensitive, selective and reliable sensing and biosensing methods for the detection of BPs using electrochemistry, fluorescence, colorimetry, surface plasmon resonance, luminescence, ELISAs, circular dichroism, resonance Rayleigh scattering and adsorption techniques in plastic products, food samples, food packaging, industrial wastes, pharmaceutical products, human body fluids and many other matrices. It summarizes the advances in sensing and biosensing methods for the detection of BPs since 2010. Furthermore, the article discusses challenges and future perspectives in the development of novel sensing methods for the detection of BP analogs.

Small-Molecule Dengue Virus Co-imprinting and Its Application as an Electrochemical Sensor

Polymers can be synthesized to recognize small molecules. This is achieved by introducing the target molecule during monomer self-assembly, where they can be incorporated during cross-linking polymerization. Following additional pre-processing, the material obtained can then be applied as a sensing layer for these molecules in many applications. The sensitivity of the polymers depends on the "active sites" imprinted on the surface. Increasing the number of active sites on the polymers surface can be achieved by using nanoparticles as a platform to support and concentrate the molecules for imprinting. In this work, we report the first use of dengue virus as a supporting nanoparticle to make for a more effective polymer composite sensor for the detection of bisphenol A (BPA), which is an environmental contaminant. The dengue virus has a nanoparticle size of around 100 nm and its surface provides regions where lipids and hydrophobic compounds can bind, making it an ideal support. The mixing of BPA with dengue prior to monomer self-assembly led to imprinted polymer surfaces with much higher density BPA binding sites and a limit of detection of 0.1 pm. We demonstrate that a BPA-dengue co-imprinting polymer composite sensor shows a very high sensitivity for BPA, but with lower production costs and technical requirements than other comparable methods.

Aptamer-functionalized nanoporous gold film for high-performance direct electrochemical detection of bisphenol A in human serum

In the present work, a highly sensitive and selective biosensor based on aptamer-functionalized nanoporous gold film (NPGF) was successfully developed for direct electrochemical detection of bisphenol A (BPA). NPGF was prepared by dealloying Ag from Au/Ag alloy leaf in concentrated nitric acid. The obtained NPGF was attached onto glassy carbon electrode and then was functionalized with BPA-specific aptamer via the formation of Au-S bond. The fabrication of the sensor was characterized by scanning electron microscopy and X-ray photoelectron spectroscopy. NPGF exhibited excellent electrocatalytic activity towards the redox reaction of BPA, which ensured high sensitivity of the sensor. The aptamer-captured BPA showed a pair of redox peaks around 0.35/0.28 V (vs. Ag/AgCl). The experimental parameters in terms of aptamer concentration, reaction time, pH, and temperature were optimized. The calibration plot showed a linear range from 0.1 nM to 100 nM BPA with a remarkable detection limit of 0.056±0.004 nM BPA. Particularly, the successful application of the developed sensor for the detection of BPA in human serum samples suggests its promising potential for clinical diagnosis.

XPS in development of chemical sensors

XPS represents a powerful tool for investigation of chemistry involved in chemical sensors, as analytes and recognition elements interact at a device surface, the region analyzed by the spectroscopic technique.