Lab-on-a-chip paper-based electrochemically assisted solid-phase microextraction and ion selective sensor for determination of naproxen in biological fluid samples.

Background: The integration of paper-based analytical devices with lab-on-a-chip technology has opened up new possibilities for miniaturized, rapid, low cost and portable diagnostic testing in resource limited settings. This work introduces an integrated lab-on-a-chip platform coupling paper-based analytical devices (LOC-PADs) for dual usage: electrochemically controlled solid-phase microextraction (EC-SPME) and determination of naproxen (NAP) by potentiometric ion-selective electrode (ISE) in biological samples.

Results: Conductive papers were successfully fabricated by a chemical procedure.

Silver Nanoclusters as Label Free Non-enzymatic Fast Glucose Assay with the Fluorescent Enhancement Signal.

A simple and low-cost green preparation method was used for BSA capped silver nanoclusters (BSA-Ag NCs) as turn on fluorescent probe for glucose. Non-enzymatic fast glucose detection assay with a widest concentration range was proposed which requires neither nanoclusters (NCs) modification nor complicated enzyme immobilization. The DLS analysis, HRTEM patterns, fluorescence and UV-visible measurement well supported the synthesis product.

Picomolar detection of As(III) ions by using hydrothermal synthesis of functionalized polymer dots as a highly selective fluorescence sensor.

Arsenic is a toxic and ubiquitous metalloid that leads to a widespread health risk to human beings and other living organisms. In this paper, a novel water-soluble fluorescent probe based on functionalized polypyrrole dots (FPPyDots) was designed and applied to determine As(III) selectively and sensitively in aqueous media. FPPyDots probe was synthesized by using a hydrothermal method, via the facile chemical polymerization of pyrrole (Py) and cysteamine (Cys) and then functionalized with ditheritheritol (DTT).

Dynamic headspace solid-phase extraction at room temperature: a theoretical model, method, and application for propofol analysis.

Herein, a simple dynamic headspace solid-phase extraction (DHS-SPE) process at room temperature was used for a material that is sensitive to increase in the temperature. A proposed method was implemented to rapidly extract propofol (PF) from a complex matrix before fluorescence spectroscopy analysis, within a short sampling time without involving a hot plate or stirrer. A mini diaphragm pump was used to circulate the headspace gas.

Chemical reduction as a facile colorimetric approach for selective TNT detection by spectrophotometry and photothermal lens spectroscopy.

In this study, the simple determination of TNT is achieved through the vivid stable red color products generated after chemically reduction by NaBH as a common and accessible reducing/colorimetric reagent. Some other nitroaromatics were impressed under reduction reaction and led to the colorful products. The color of these reduced nitroaromatics were unstable and approximately vanished after some few minutes which ameliorated the selectivity in TNT determination.

Electrochemically controlled solid-phase microextraction based on conductive molecularly imprinted polymer combined with ion mobility spectrometry for separation and determination of thiopental.

In this work, electrochemically controlled solid-phase microextraction (EC-SPME) based on conductive molecularly imprinted polymer (CMIP) is coupled with ion mobility spectrometry (IMS) for analysis of thiopental (TP) as an anesthesia drug. The CMIP film was synthesized on the modified stainless steel wire surface by electropolymerization of pyrrole in the presence of TP as the template anion. Under the optimal experimental conditions, the developed method offered good linear range from 3.

Rapid simultaneous determination of ketamine and midazolam in biological samples using ion mobility spectrometry combined by headspace solid-phase microextraction.

Ketamine (Ket) and midazolam (Mdz) are among well-known anesthetic agents which frequently coadministered in surgical procedures and emergency department. Only a few reports have been published for the simultaneous analysis of these compounds. In the present study, we reported a simple, sensitive, and rapid method for simultaneous determination of Ket and Mdz based on headspace solid-phase microextraction coupled with ion mobility spectrometry (HS-SPME-IMS).

Noninvasive Detection of Ammonia in the Breath of Hemodialysis Patients Using a Highly Sensitive Ammonia Sensor Based on a Polypyrrole/Sulfonated Graphene Nanocomposite.

In this work, we fabricated fast-responsive and highly sensitive chemiresistive sensors based on nanocomposites of polypyrrole and graphitic materials such as graphene oxide (GO), reduced graphene oxide (RGO), and sulfonated graphene (SRGO) by an in situ chemical oxidative polymerization method. The synthesized nanocomposites were characterized using field emission scanning electron microscopy (FESEM), energy-dispersive spectroscopy (EDS), Fourier transform infrared (FT-IR) spectroscopy, and X-ray diffraction (XRD). The effects of the operating temperature of different nanocomposites were investigated at four temperatures (28, 40, 50, and 60 °C), and the results were compared with that of the polypyrrole-based sensor.

Spectrofluorimetric study of the complexation of ochratoxin A and Cu: Towards the hybrid fluorimetric sensor and visual detection of ochratoxin A in wheat flour samples from farm to fork.

In this study, the ochratoxin A (OTA) interaction with some metal cations exhibits a quenching effect of the Cu, Co, and Ni in the OTA intrinsic fluorescence intensity. The property of the OTA fluorescence change in complexation with the Cu has been applied in developing a label-free and selective fluorimetric sensor for fast detection of the OTA trace amounts in wheat flour samples. The achieved color difference map (CDM) based on the spectral profile provides the technical support for the rapid visual sensing of OTA in the wheat flour samples.

Vertically grown nanosheets conductive polypyrrole as a sorbent for nanomolar detection of salicylic acid.

A selective detection strategy for salicylic acid (SA) based on the electrosorption/electrodesorption process using an electrochemically controlled solid phase extraction (EC-SPME) configuration is presented. We used conducting polymer polypyrrole (PPy) bearing the anionic dopant nitrate (PPy/nitrate) as a sorbent element for the extraction of SA in plasma and urine samples. The vertically grown nanosheets conducting film was directly synthesized by cyclic voltammetry method on a rod-shaped stainless steel electrode.

Highly selective detection of methanol in aqueous and ethanol medium based on hybrid ZnS:Mnquantum dots/N-methylpolypyrrole as a fluorescence switchable sensor.

Methanol is highly toxic for human, so methanol detection is valuable especially in water and ethanol medium without complicated and time consuming procedure. In this work, we present a new fluorescence probe for direct detection of methanol in aqueous and ethanol medium based on the ZnS:Mn quantum dot (QDs) and soluble N-methylpolypyrrole (NMPPy) hybrid. Moreover, the number of spectroscopic techniques were used to study the chemical composition and optical properties of the resultant QDs as well as investigation on the sensing mechanism toward methanol.

Synthesis of highly fluorescent water-soluble polypyrrole for cell imaging and iodide ion sensing.

Conjugated polymers for bioimaging and sensing chemical/biological reagents have received much attention owing to their outstanding photophysical properties. However, most conventional synthetic strategies result in aggregates of conjugated polymers with limited solubility in most common organic and aqueous solvents. Therefore, advancement in molecular design and synthetic pathways is required to tune the optical and solubility properties of the resulting conjugated polymers.

CdS QDs/N-methylpolypyrrole hybrids as fluorescent probe for ultrasensitive and selective detection of picric acid.

Inorganic-organic hybrids are an advanced class of luminescent materials showing great promise for fabrication of highly sensitive and selective optical sensors. In the present study, a novel CdS quantum dots/N-methylpolypyrrole (CdS QDs/NMPPY) hybrid was synthesized via the direct polymerization of NMPPY on L-cysteine capped CdS QD aggregates. A number of characterization techniques including FTIR, DLS, FESEM, UV-vis, and fluorescence spectroscopies were used to study the chemical composition, morphology and optical properties of the resultant QDs/polymer hybrid.

Hybrid Optoelectrochemical Sensor for Superselective Detection of 2,4,6-Trinitrotoluene Based on Electrochemical Reduced Meisenheimer Complex.

2,4,6-Trinitrotoluene (TNT) is known as one of the most used explosives, and its detection is significant in public security, human health, and environmental protection. The fabrication of absorbance based optical sensors for TNT is a serious challenge due to poor selectivity and sensitivity. We reported the design and fabrication of a superselective hybrid optoelectrochemical sensor based on the electrochemical reduction of Meisenheimer complex in a deep eutectic solvent (DES) modified with n-butylamine (nBA) for determination of TNT.

An Optical Configuration of Crossed-Beam Photothermal Lens Spectrometer Operating at High Flow Velocities and Its Application for Cysteine Determination in Human Serum and Saliva.

Photothermal lens spectrometry (TLS) is a high sensitive technique for trace determination of nonfluorescent materials. Previous photothermal lens spectrometers suffer from operating limitations at high flow velocities, arising from taking the heated element off the probe beam direction, which results in a decrease in the thermal lens (TL) signal. Herein, we describe an optical configuration of the crossed-beam photothermal lens in transversal flow mode in which the propagating direction of the probe beam and liquid sample flow azimuth are concentric (CBTC).

Facile preparation and characterization of new green emitting carbon dots for sensitive and selective off/on detection of Fe ion and ascorbic acid in water and urine samples and intracellular imaging in living cells.

Carbon dots (CDs) have gained great attention as multifunctional materials because of their interesting properties and general applicability. However, there are some reports for the preparation of highly luminescent green-emitting CDs (G-CDs), although these reports seem not to be extensible. Herein, new G-CDs (quantum yield: 27.

Determination of biogenic amines in canned fish samples using head-space solid phase microextraction based on nanostructured polypyrrole fiber coupled to modified ionization region ion mobility spectrometry.

The head-space solid phase microextraction (HS-SPME) was applied to extraction and determination of histamine (HIS), putrescine (PUT), cadaverine (CAD), tyramine (TYR) in canned fish samples by ion mobility spectrometry (IMS) without any derivatization process. HIS and CAD have the same mobilities in nitrogen as buffer gas and their corresponding peaks are severely overlapped in ion mobility spectrum. Peak separation was acquired in the presence of 18-crown-6 vapor as complexation reagent into carrier gas and modified ionization region of IMS (MIR-IMS) at optimum flow rate.

Electrically induced fluorescence Fe sensing behavior of nanostructured Tiron doped polypyrrole.

Nanostructured polypyrrole (PPy) film doped with Tiron was electrodeposited from aqueous solution on the surface of transparent electrode and used for sensitive, selective and rapid electrically controlled fluorescence detection of Fe in aqueous media. The fluorescence intensity of PPy-Tiron film decreases linearly in the presence of Fe by applying negative potential over a concentration range from 5.0 × 10 to 1.

Online Spectroscopic Monitoring of Drug Release Kinetics from Nanostructured Dual-Stimuli-Responsive Conducting Polymer.

Purpose: The potential of electrochemical/temperature dual stimuli-responsive conducting polymer to be used as general drug delivery systems. It allows on-demand release of incorporated drug is kinetically investigated in real time.

Methods: Online spectroscopic monitoring was used to investigate the electrochemically/thermally controlled release behavior of a model drug (naproxen) from drug-doped polypyrrole (DDPPy) film.

Photophysical Diversity of Water-Soluble Fluorescent Conjugated Polymers Induced by Surfactant Stabilizers for Rapid and Highly Selective Determination of 2,4,6-Trinitrotoluene Traces.

The increasing application of fluorescence spectroscopy in development of reliable sensing platforms has triggered a lot of research interest for the synthesis of advanced fluorescent materials. Herein, we report a simple, low-cost strategy for the synthesis of a series of water-soluble conjugated polymer nanoparticles with diverse emission range using cationic (hexadecyltrimethylammonium bromide, CTAB), anionic (sodium dodecylbenzenesulfonate, SDBS), and nonionic (TX114) surfactants as the stabilizing agents. The role of surfactant type on the photophisical and sensing properties of resultant polymers has been investigated using dynamic light scattering (DLS), FT-IR, UV-vis, fluorescence, and energy dispersive X-ray (EDS) spectroscopies.

Polypyrrole nanowire as an excellent solid phase microextraction fiber for bisphenol A analysis in food samples followed by ion mobility spectrometry.

A polypyrrole nanowire coated fiber was prepared and used in head-space solid phase microextraction coupled with ion mobility spectrometry (HS-SPME-IMS) to the analysis of bisphenol A (BPA) in canned food samples, for the first time. This fiber was synthesized by electrochemical oxidation of the monomer in aqueous solution. The fiber characterization by scanning electron microscopy (SEM) revealed that the new fiber exhibited two-dimensional structures with a nanowire morphology.

Determination of furfural and hydroxymethylfurfural from baby formula using headspace solid phase microextraction based on nanostructured polypyrrole fiber coupled with ion mobility spectrometry.

Furfural (Fu) and hydroxymethylfurfural (HMFu) are extracted using a dodecylbenzenesulfonate-doped polypyrrole coating as a fiber for headspace solid phase microextraction (HS-SPME) method in baby formula samples and detected using ion mobility spectrometry (IMS). Sample pH, salt effect, extraction time and temperature were investigated and optimized as effective parameters in HS-SPME. The calibration curves were linear in the range of 20-300 ng g(-1) (R(2)>0.

Functionalized gold nanoparticle-polypyrrole nanobiocomposite with high effective surface area for electrochemical/pH dual stimuli-responsive smart release of insulin.

A novel functionalized gold nanoparticle-polypyrrole-nanobiocomposite (PPy-FGNP-NBC) with large effective surface area was fabricated for electrical/pH dual stimuli-responsive local delivery of insulin. The fabrication method involves simple electrodeposition and immobilization processes without use of organic solvents. Release studies based on the nature of insulin-surface binding indicated that release was promoted for PPy-FGNP-NBC.

Nanostructured biocompatible thermal/electrical stimuli-responsive biopolymer-doped polypyrrole for controlled release of chlorpromazine: kinetics studies.

Biocompatible nanostructured conductive heparin-doped polypyrrole film was fabricated and employed as a high-capacity cation exchanger for programmable release of neuroleptic drug, chlorpromazine (CPZ) with thermally and electrical dual-stimulation. Releasing behavior were studied at different applied potentials and temperatures by in-situ monitoring of UV absorbance measurements. Three mathematical models (Higuchi, Power, and Avrami equation) were employed to investigate kinetics of the release.

Photochemically induced fluorescence studies of 1,3-diethyl-1,3-diphenylurea as stabilizer and its quantitative determination.

The photochemically induced fluorescence (PIF) studies of 1,3-diethyl-1,3-diphenylurea or ethyl centralite (EC) as stabilizer have been carried out under various conditions. Influences of solvent type (water, methanol, acetonitrile and chloroform), oxygen dependence and UV irradiation time on the spectroscopic properties of EC were studied. In order to obtain a better understanding of the photochemical mechanism, products were identified by mass spectrometry study.