Fabrication of hybrid PVA-PVC/SnZnOx/SWCNTs nanocomposites as Sn2+ ionic probe for environmental safety

Ionic Organic Network-based C3-symmetric@Triazine core as a selective Hg+2 sensor

The C3-symmetry ionic polymer PPyTri has been designed with multi-walled carbon nanotubes (MWCNTs) or graphene nanoplatelets (GNPs) and studied as an ultrasensitive electrochemical sensor for trace Hg(II) detection. The synthesis approach incorporated attaching three pyridinium cationic components with chloride anions to the triazine core. The precursors, BPy, were synthesized using a condensation process involving 4-pyridine carboxaldehyde and focused nicotinic hydrazide. The polymer PPyTri was further modified with either MWCNTs or GNPs. The resulting ionic polymer PPyTri and its fabricated nanocomposites were characterized using infrared (IR), nuclear magnetic resonance (NMR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and powder X-ray diffraction (XRD). The analysis revealed that both the polymer and its nanocomposites have semi-crystalline structures. The electroactivity of the designed nanocomposites toward Hg + 2 ions revealed that among the nanocomposites and bare copolymer, the glassy carbon electrode (GCE) adapted with the PPyTri GNPs-5% exhibited the greatest current response over a wide range of Hg + 2 concentrations. The nanocomposite-modified electrode presented an excellent sensitivity of 83.33 µAµM - 1 cm - 2, a low detection limit of 0.033 nM, and a linear dynamic range of 0.1 nM to 0.01 mM (R2 = 0.9945).

Sensitive Cr3+ sensor based on novel poly(luminol-co-1,8-diaminonaphthalene)/CeO2/MWCNTs nanocomposites

In this study, poly(luminol-co-1,8-diaminonaphthalene) (PLim-DAN) was synthesized and subsequently modified with MWCNTs and CeO2 NPs. The synthesized nanocomposites were analyzed using IR, SEM, TEM, and XRD. Furthermore, a comprehensive set of thermal behavior measurements were taken using TGA/DTG analysis. Next, the electroactivity of the developed nanocomposites was tested as an electrochemical sensor to measure the concentration of Cr3+ ions in phosphate buffers. The GCE adapted with the PLim-DAN/CeO2/CNTs-10% nanocomposite (NC) exhibited the highest current response among the other compositions and copolymers. The fabricated nanocomposite sensor showed high sensitivity, with a value of 19.78 μA μM-1 cm-2, and a low detection limit of 4.80 ± 0.24 pM. The analytical performance was evaluated by plotting a current calibration curve versus the concentration of Cr3+ ions. It was found to be linear (R2 = 0.9908) over the range of 0.1 nM to 0.1 mM, identified as the linear dynamic range (LDR). This electrochemical sensor demonstrated that it could be a useful tool for environmental monitoring by accurately detecting and measuring carcinogenic Cr3+ ions in real-world samples.

Nanosheet composed of gold nanoparticle/graphene/epoxy resin based on ultrasonic fabrication for flexible dopamine biosensor using surface-enhanced Raman spectroscopy

Construction of a fast, easy and sensitive neurotransmitters-based sensor could provide a promising way for the diagnosis of neurological diseases, leading to the discovery of more effective treatment methods. The current work is directed to develop for the first time a flexible Surface-Enhanced Raman Spectroscopy (SERS) based neurotransmitters sensor by using the ultrasonic-assisted fabrication of a new set of epoxy resin (EPR) nanocomposites based on graphene nanosheets (GNS) using the casting technique. The perspicuous epoxy resin was reinforced by the variable loading of GNS giving the general formula GNS/EPR1-5. The designed products have been fabricated in situ while the perspicuous epoxy resin was formed. The expected nanocomposites have been fabricated using 3%, 5%, 10%, 15% and 20% GNS loading was applied for such fabrication process. The chemical, physical and morphological properties of the prepared nanocomposites were investigated by using Fourier transforms infrared spectroscopy, X-ray diffraction, Thermogravimetric analysis, Differential Thermal gravimetry, and field emission scanning electron microscopy methods. The GNS/EPR1-5 nanocomposites were decorated with a layer of gold nanoparticles (Au NPs/GNS/EPR) to create surface-enhanced Raman scattering hot points. The wettability of the Au NPs/GNS/EPR was investigated in comparison with the different nanocomposites and the bare epoxy. Au NPs/GNS/EPR was used as a SERS-active surface for detecting different concentrations of dopamine with a limit of detection of 3.3 µM. Our sensor showed the capability to detect low concentrations of dopamine either in a buffer system or in human serum as a real sample.

A non-enzymatic electrochemical approach for l-lactic acid sensor development based on CuO·MWCNT nanocomposites modified with a Nafion matrix

Copper oxide decorated multi-walled carbon nanotube nanocomposites (CuO·MWCNT NCs) were prepared using a simple wet-chemical technique in basic medium.