Highly sensitive hydrazine chemical sensor based on mono-dispersed rapidly synthesized PEG-coated ZnS nanoparticles

Century Impact of Macromolecules for Advances of Sensing Sciences

Impact of macro molecular theory on the progress of sensing sciences and technology has been presented in the light of materials developments, advances in physical and chemical properties. The chronological advances in the properties of macromolecules have significantly improved the sensing performances towards gases, heavy metals, biomolecules, hydrocarbon, and energetic compounds in terms of unexplored sensing parameters, durability, and working lifetime. In this review article, efforts have been made to correlate the advances in structure and interactivity of macro-molecules with their sensing behavior and working performances. The significant findings on the macromolecules towards advancing the sensing sciences are highlighted with the suitable illustration and schemes to establish it as a potential “microanalytical technique” along with existing challenges.

Rapid and highly selective electrochemical sensor based on ZnS/Au-decorated f-multi-walled carbon nanotube nanocomposites produced via pulsed laser technique for detection of toxic nitro compounds

Novel ZnS/Au/f-multi-walled carbon nanotube (MWCNT) nanostructures were produced via a pulsed laser-assisted technique followed by a wet chemical process. ZnS nanospheres were synthesized via pulsed laser ablation of a Zn target in DMSO, which was used as a solvent and sulfur source. Notably, no additional sulfur sources, surfactants, or reducing agents were used during the synthesis. The structure and morphology of the prepared materials were characterized by X-ray diffraction, micro-Raman spectroscopy, X-ray photoelectron spectroscopy, ultraviolet-visible spectroscopy, field emission scanning electron microscopy, and high-resolution transmission electron microscopy. The fabricated electrochemical sensor based on ZnS/Au/f-MWCNT nanocomposites exhibited rapid and highly selective detection of a toxic pollutant, namely 4-nitrophenol (4-NP). Linear sweep voltammetry analysis revealed that the optimized ZnS/Au10/f-MWCNT3 nanocomposite displayed a wide linear dynamic response (10-150 μM) with high sensitivity (0.8084μAμM^-1cm^-2) and low limit of detection (30 nM). The excellent 4-NP sensing performance of the modified electrode was attributed to the availability of numerous active sites (electrochemical surface area=0.00369μFcm^-2) and an enhanced electron transfer rate. Interference and stability studies were also conducted. A 100-fold excess of competing ions (Na⁺, K⁺, Mg²⁺, Cl^-, NO₃^-, 4-AP, AA, and 2-NP) did not interfere with the selective detection of 4-NP. The newly fabricated ZnS/Au10/f-MWCNT3 nanocomposite could be an effective sensor for the selective and sensitive detection of toxic organic nitro compounds.

Graphene Oxide/Polyethylene Glycol-Stick for Thin Film Microextraction of β-Blockers from Human Oral Fluid by Liquid Chromatography-Tandem Mass Spectrometry

A wooden stick coated with a novel graphene-based nanocomposite (Graphene oxide/polyethylene glycol (GO/PEG)) is introduced and investigated for its efficacy in solid phase microextraction techniques. The GO/PEG-stick was prepared and subsequently applied for the extraction of β-blockers, acebutolol, and metoprolol in human oral fluid samples, which were subsequently detected by liquid chromatography tandem mass spectrometry (LC-MS/MS). Experimental parameters affecting the extraction protocol including sample pH, extraction time, desorption time, appropriate desorption solvent, and salt addition were optimized. Method validation for the detection from oral fluid samples was performed following FDA (Food and Drug Administration) guidelines on bioanalytical method validation. Calibration curves ranging from 5.0 to 2000 nmol L⁻¹ for acebutolol and 25.0 to 2000 nmol L⁻¹ for metoprolol were used. The values for the coefficient of determination (R²) were found to be 0.998 and 0.996 (n = 3) for acebutolol and metoprolol, respectively. The recovery of analytes during extraction was 80.0% for acebutolol and 62.0% for metoprolol, respectively. The limit of detections (LODs) were 1.25, 8.00 nmol L⁻¹ for acebutolol and metoprolol and the lower limit of quantifications (LLOQ) were 5.00 nmol L⁻¹ for acebutolol and 25.0 nmol L⁻¹ for metoprolol. Validation experiments conducted with quality control (QC) samples demonstrated method accuracy between 80.0% to 97.0% for acebutolol and from 95.0% to 109.0% for metoprolol. The inter-day precision for QC samples ranged from 3.6% to 12.9% for acebutolol and 9.5% to 11.3% for metoprolol. Additionally, the GO/PEG-stick was demonstrated to be reusable, with the same stick observed to be viable for more than 10 extractions from oral fluid samples.

Hydroxyapatite/chemically reduced graphene oxide composite: Environment-friendly synthesis and high-performance electrochemical sensing for hydrazine

It is unexpectedly found that, the in-situ growth of hydroxyapatite (HAP) on graphene oxide (GO) under a moderate temperature (85°C) can effectively trigger the reduction of GO, which needs neither extra reducing agents nor high-temperature thermal treatment. The transmission electron microscope (TEM) experiment demonstrates that the rod-like HAP particles are well attached on the surface of reduced GO (rGO) to form the composite. Electrochemical sensing assays show that the synthesized HAP-rGO nanocomposite presents excellent electrocatalytic capacity for the oxidation of a toxic chemical of hydrazine. When the HAP-rGO modified electrode was utilized as an electrochemical sensor for hydrazine detection, outstanding performances in the indexes of low fabrication cost, short response time (~2s), wide linear range, low detection limit (0.43μM), and good selectivity were achieved. The developed sensor also shows satisfactory results for the detection of hydrazine in real industrial wastewater sample were achieved.

A new 2-amino-3-pynanopyrane-3- carbonitrile derivative for electrocatalytic oxidation and determination of hydrazine

A noble glassy carbon electrode modified with Au nanoparticles and 2-amino-4-(3,4-dihydroxyphenyl)-6-(hydroxymethyl)-8-oxo-4,8-dihydropyrano[3,2-b]pyran-3-carbonitrile, was fabricated for electrocatalytic determination of hydrazine (AuNPs/APP/GCE). Large over-potential and interference of some species are two limitation factors for the determination of hydrazine at bare electrode. This modified electrode is able to shift a signal to the negative potential, and can amplify the oxidation current of hydrazine by 28.0 time, compared to bare electrode. The diffusion coefficient, D, and the heterogeneous rate constant, k_h, for the oxidation of hydrazine at the modified surface were calculated by chronoamperometric studies. Finally, the fabricated sensor was agreeably utilized for the determination of hydrazine in real samples.

Ultrasensitive hydrazine sensor fabrication based on Co-doped ZSM-5 zeolites for environmental safety

Various Co-loaded ZSM-5 zeolites (Co-ZSM-5) were prepared and the details of their structural, morphological and elemental properties characterized by different conventional methods.

Development of highly-sensitive hydrazine sensor based on facile CoS2–CNT nanocomposites

Cobalt pyrite-decorated carbon nanotube nanocomposites (CoS₂–CNT NCs) were prepared by a simple wet-chemical method and applied for a selective and sensitive hydrazine sensor.

Highly sensitive luminescent sensor for cyanide ion detection in aqueous solution based on PEG-coated ZnS nanoparticles

Using polyethylene glycol (PEG) coated ZnS nanoparticles (NPs), a novel and highly sensitive luminescent sensor for cyanide ion detection in aqueous solution has been presented. ZnS NPs have been used to develop efficient luminescence sensor which exhibits high reproducibility and stability with the lowest limit of detection of 1.29×10(-6) mol L(-1). The observed limit of detection of the fabricated sensor is ~6 times lower than maximum value of cyanide permitted by United States Environmental Protection Agency for drinking water (7.69×10(-6) mol L(-1)). The interfering studies show that the developed sensor possesses good selectivity for cyanide ion even in presence of other coexisting ions. Importantly, to the best of our knowledge, this is the first report which demonstrates the utilization of PEG- coated ZnS NPs for efficient luminescence sensor for cyanide ion detection in aqueous solution. This work demonstrates that rapidly synthesized ZnS NPs can be used to fabricate efficient luminescence sensor for cyanide ion detection.