High performance polyaniline/vanadyl phosphate (PANI–VOPO4) nano composite sheets prepared by exfoliation/intercalation method for sensing applications

Metal-organic frameworks (MOFs) composite of polyaniline-CNT@aluminum succinate for non-enzymatic nitrite sensor

Nitrite has been linked to a variety of health issues, as well as cancer and oxygen deficiency when its allowable limit is exceeded. Nitrite monitoring and detection are required due to the negative effects on public health. Metal-organic frameworks (MOFs)-based nanomaterials/composites have recently been shown to have the potential for various biological and medical applications like sensing, imaging, and drug delivery. As a result, this research creates an efficient electrochemical sensor by incorporating MOFs into polyaniline (PANI)/carbon nanotube (CNT) cast on the GCE. In situ oxidative polymerization was used to construct an aluminum succinate MOF (Al-Succin)-incorporated CNT/PANI nanocomposite (PANI/CNT@Al-Succin) and well characterized by various characterization techniques, namely, field emission scanning electron microscopy (FE-SEM), Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction spectroscopy (XRD), X-ray photoelectron spectroscopy (XPS), thermogravimetric-differential thermal analysis (TGA-DTA), cyclic voltammetry (CV), and four probes to measure DC electrical conductivity. Cyclic voltammetry and linear sweep voltammetry techniques were employed to detect nitrite on the surface of PANI/CNT@Al-Succin-modified glassy carbon electrode (GCE). PANI/CNT@Al-Succin-modified GCE demonstrated good current response and electrocatalytic property towards nitrite compared to bare GCE. The newly synthesized electrode exhibited a high electrocatalytic activity towards nitrite oxidation and showed a linear response ranging from 5.7 to 74.1 μM for CV and 8.55-92.62 μM for LSV. The obtained LOD values for CV (1.16 μM) and LSV (0.08 μM) were significantly below the WHO-defined acceptable nitrite limit in drinking water. Results of recovery studies for real samples of apple juice, orange juice, and bottled water were 98.92%, 99.38%, and 99.90%, respectively. These values show practical usability of PANI/CNT@Al-Succin in real samples.

Development of Cd (II) Ion Probe Based on Novel Polyaniline-Multiwalled Carbon Nanotube-3-aminopropyltriethoxylsilane Composite

Cadmium belongs to the group of potentially toxic metals that have high health and environmental significance. Due to its adverse effects on the environment, this study develops an effective electrochemical sensor for detecting a polyaniline-multiwalled carbon nanotube-3-aminopropyltriethoxysilane (PANI-MWCNT-APTES) substrate cast on the GCE. The as-prepared PANI-MWCNT-APTES was prepared by a wet chemical method, and its formation was investigated using several techniques. As a result, the prepared material exhibited a limit of detection of 0.015 µM for cadmium ions (Cd²⁺) in the linear dynamic range of 0.05 µM to 50 µM. Furthermore, the PANI-MWCNT-APTES-modified GCE current response was stable, repeatable, reproducible, and short. In addition, PANI-MWCNT-APTES/GCE was harnessed for the first time for cadmium detection in real water samples, and the result was satisfactory. Therefore, the recorded results suggest that the newly designed PANI-MWCNT-APTES is a promising material for detecting Cd in the near future for human health and environmental protection.

Efficient Synthesis and Characterization of Polyaniline@Aluminium-Succinate Metal-Organic Frameworks Nanocomposite and Its Application for Zn(II) Ion Sensing

A new class of conductive metal-organic framework (MOF), polyaniline- aluminum succinate (PANI@Al-SA) nanocomposite was prepared by oxidative polymerization of aniline monomer using potassium persulfate as an oxidant. Several analytical techniques such as FTIR, FE-SEM, EDX, XRD, XPS and TGA-DTA were utilized to characterize the obtained MOFs nanocomposite. DC electrical conductivity of polymer-MOFs was determined by four probe method. A bare glassy carbon electrode (GCE) was modified by nafion/PANI@Al-SA, and examined for Zn (II) ion detection. Modified electrode showed improved efficiency by 91.9%. The modified electrode (PANI@Al-SA/nafion/GCE) exhibited good catalytic property and highly selectivity towards Zn(II) ion. A linear dynamic range of 2.8–228.6 µM was obtained with detection limit of LOD 0.59 µM and excellent sensitivity of 7.14 µA µM⁻¹ cm⁻². The designed procedure for Zn (II) ion detection in real sample exhibited good stability in terms of repeatability, reproducibility and not affected by likely interferents. Therefore, the developed procedure is promising for quantification of Zn(II) ion in real samples.

Acute toxicity assessment of polyaniline/Ag nanoparticles/graphene oxide quantum dots on Cypridopsis vidua and Artemia salina

Nanotoxicology is argued and considered one of the emerging topics. In this study, polyaniline (PANI)/2-acrylamido-2-methylpropanesulfonic acid (AMPSA) capped silver nanoparticles (NPs)/graphene oxide (GO) quantum dots (QDs) nanocomposite (PANI/Ag (AMPSA)/GO QDs NC) as a nanoadsorbent has a potential for removal of toxic hexavalent chromium (Cr(VI)) ions from water. The acute toxicity of this NC was evaluated on Artemia salina and freshwater Ostracods (Cypridopsis vidua) larvae for 48 h. The measurements were made at 24 and 48 h with 3 repetitions. The 50% effective concentration (EC50) values of the NC were determined after the exposure of these organisms. According to the results of the optical microscope, it was found that both experimental organisms intake the NC. In the toxicity results of Ostracods, the NC had a highly toxic effect only at 250 mg/L after 48 h and the EC50 value was 157.6 ± 6.4 mg/L. For Artemia salina individuals, it was noted that they were less sensitive than the Ostracods and EC50 value was 476 ± 25.1 mg/L after 48 h. These results indicated that PANI/Ag (AMPSA)/GO QDs NC has low toxicity towards both investigated organisms.

Synthesis of ZnO@poly-o-methoxyaniline nanosheet composite for enhanced NH3-sensing performance at room temperature

Poly-o-methoxyaniline (POMA) and zinc oxide (ZnO) composites were prepared via in situ polymerization and characterized by thermogravimetry thermal analysis, X-ray diffraction analysis, scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and N₂ sorption measurement. The composites show different morphology when the ratio of POMA and ZnO varies. At a ratio of 2:2, the composite shows thinner nanosheet structure with smooth surface and exhibits best response to NH₃ at room temperature. The ZnO@POMA nanosheet sensor shows good selectivity and a wide response range (linear ranges from 0.05-1 pmm and 10-100 ppm of NH₃). The lowest detection limit reaches 0.05 ppm. The sensor exhibits good reversibility. Based on the testing results of ultraviolet diffuse reflection spectroscopy and Kelvin probe technique, the adsorption and desorption of NH₃ molecules on the sensing material and the formation of p-n heterostructure between ZnO and POMA and their synergistic effects are further explained. More importantly, the sensor possessed excellent moisture resistance. The overall test results of ZnO@POMA show that the sensor has good practical applicability for detecting trace NH₃ at room temperature. Graphical abstract.

Chemical-resistant ammonia sensor based on polyaniline/CuO nanoparticles supported on three-dimensional nitrogen-doped graphene-based framework nanocomposites

A novel ammonia (NH₃) chemical sensor is presented with ultra-high response, good selectivity, fast response, and long-term stability using detecting layer of polyaniline/cupric oxide nanoparticles supported on three-dimensional nitrogen-doped graphene-based frameworks (PANI/CuO@3D-NGF) nanocomposite. The NH₃ gas sensing response of the PANI/CuO@3D-NGF nanocomposite was studied by resistivity method in low concentration range of 50 ppb-100 ppm at room temperature. The PANI/CuO@3D-NGF nanocomposite was prepared through in situ polymerization of PANI on the CuO@3D-NGF with a high surface area. Morphological and structural analysis revealed that the ultrathin 3D interconnected graphene substrate maximizes the surface area. It is also shown that the CuO nanoparticles offer active adsorption sites for free NH₃ molecule. The PANI/CuO@3D-NGF nanocomposite gas sensor shows the response of 930% to 100 ppm NH₃ with an outstanding low detection limit of 50 ppb and an average response time of 30 s at room temperature. The excellent sensing performance of the PANI/CuO@3D-NGF nanocomposite was attributed to 3D interconnected porous structure, remarkable enhancement of charge carriers as a result of CuO@3D-NGF, and modified π-interactions between molecules. Graphical abstract.

Detection of 3,4-diaminotoluene based on Sr0.3Pb0.7TiO3/CoFe2O4 core/shell nanocomposite via an electrochemical approach

We reported a scalable sol–gel method for the preparation of Sr_0.3Pb_0.7TiO₃/CoFe₂O₄ core–shell magnetic nanocomposite with a finely controlled shell and evaluated its efficiency as an electrochemical sensor for the selective detection of 3,4-diaminotoluene.

Synthesis and characterization of polyaniline-drug conjugates as effective antituberculosis agents

Polyaniline (PANI) and its drug composites with some drugs like Neomycin (NM), Trimethoprim (TMP) and Streptomycin (ST) have been prepared by oxidative polymerization of aniline using hydrochloric acid (HA) and ammonium persulfate (APS) as a dopant and as an oxidant, respectively. The structures of PANI and PANI-drug composites were elucidated by FTIR and NMR spectroscopy, which confirmed the presence of benzenoid and quinoid rings in the synthesized compound. Molecular weight and thermal stability were determined by gel permeation chromatography (GPC) and thermogarvimetric analysis, respectively. From the GPC, PDI values of PANI-NM, PANI-TMP and PANI-ST were found to be 1.37, 1.23 and 1.56, respectively. For the study of antibacterial behavior of the synthesized PANI and PANI-drug composites, different micro-organisms, namely, four Gram positive (S. aureus MTCC 96, B. subtilis MTCC 441, S. pyogenes MTCC 442 and S. mutans MTCC 890) and four Gram negative (S. typhi MTCC 98, KL. pneumoniae MTCC 109, E. coli MTCC 443 and P. aeruginosa MTCC 1688) bacteria were selected due to their pharmacological importance. Some of the PANI-drug composites were found to show excellent results as compared to components polyaniline and drugs used for composite formation. Antituberculosis activity of the PANI and its drug composites against Mycobacterium tuberculosisH₃₇RV (acid fast Bacilli) was determined. MIC values for PANI-NM and PANI-TMP were found to be 0.12 and 0.20 µg/mL, respectively. Results suggested that some of the drug composites may be tried as potential candidates for use as an antituberculoid agent to reduce TB transmission.

Removal of a melamine contaminant with Ag-doped ZnO nanocomposite materials

In this approach, Ag-doped ZnO nanosheets (Ag/ZnO NSs) were prepared via a facile wet-chemical method using reducing agents in an alkaline medium at a low temperature.

Hydrothermal synthesis of polyaniline intercalated vanadium oxide xerogel hybrid nanocomposites: effective control of morphology and structural characterization

Structural characterization of polyaniline intercalated layered vanadium-oxide xerogel nanocomposites with different morphologies revealed from XRD patterns and FESEM/HRTEM image analyses.

Effect of Ce doping into ZnO nanostructures to enhance the phenolic sensor performance

Various Ce-doped ZnO nanostructures (Ce/ZnO NSs) were prepared by a facile wet chemical method using reducing agents in alkaline medium.