Development of an efficient phenolic sensor based on facile Ag2O/Sb2O3 nanoparticles for environmental safety

Recent advancements in Janus nanoparticle-based biosensing platforms

Nanoparticles have aided in the development of nano-based sensors for diagnostic applications. However, use of nanoparticles in the development of sensing devices for multiple analyte detection is constrained due to their inability to detect several analytes with a single type of nanoparticle. The term "Janus particle" refers to micro or nanoscale particles that have been divided into sections or compartments, each of which has a distinct set of chemical or physical properties, producing multifunctional particles endowed with distinctive qualities. Furthermore, Janus particles have the ability to perform multiple functions within a single particle at the same time, with no interference from adjacent sections. This review focuses on the use of Janus particles in the fabrication of biosensors as well as in the investigation of various properties endowed by these Janus particles for their use as biosensors. It also discusses the various types of Janus particle-based biosensors that are currently available. Finally, the limitations of Janus particles in sensor technologies and their future scope have been discussed.

Graphical abstract

Detection of L-Aspartic Acid with Ag-Doped ZnO Nanosheets Using Differential Pulse Voltammetry

Here, a sensitive voltametric electrochemical sensor probe was fabricated to reliably trace the detection of L-aspartic acid in phosphate-buffered medium using a glassy carbon electrode (GCE) layered with a film of wet-chemically prepared Ag2O-doped ZnO nanosheets (NSs). EDS, FESEM, XPS, and X-ray diffraction analyses were implemented as characterizing tools of prepared NSs to confirm the structural and compositional morphology, binding energies of existing atoms, and the crystallinity of synthesized NSs. The differential pulse voltammetry (DPV) was applied to the trace detection of L-aspartic acid, and exhibited a wide detection range of 15.0~105.0 µM, a limit of detection (3.5 ± 0.15 µM), and good sensitivity (0.2689 µA µM-1 cm-2). Besides these the precious reproducibility, stability, and efficient responses were perceived from the voltametric analysis of aspartic acid. Moreover, the proposed aspartic acid was subjected to experiments to potentially detect aspartic acid in real biological samples. Therefore, the development of an enzyme-free sensor by applying this method will be a smart technical approach in the near future.

Comparison of Magnesium and Titanium Doping on Material Properties and pH Sensing Performance on Sb2O3 Membranes in Electrolyte-Insulator-Semiconductor Structure

In this research, electrolyte-insulator-semiconductor (EIS) capacitors with Sb2O3 sensing membranes were fabricated. The results indicate that Mg doping and Ti-doped Sb2O3 membranes with appropriate annealing had improved material quality and sensing performance. Multiple material characterizations and sensing measurements of Mg-doped and Ti doping on Sb2O3 sensing membranes were conducted, including of X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM). These detailed studies indicate that silicate and defects in the membrane could be suppressed by doping and annealing. Moreover, compactness enhancement, crystallization and grainization, which reinforced the surface sites on the membrane and boosted the sensing factor, could be achieved by doping and annealing. Among all of the samples, Mg doped membrane with annealing at 400 °C had the most preferable material properties and sensing behaviors. Mg-doped Sb2O3-based with appropriate annealing are promising for future industrial ionsensing devices and for possible integration with Sb2O3-based semiconductor devices.

A Ready-to-Use Metal-Supported Bilayer Lipid Membrane Biosensor for the Detection of Phenol in Water

This work presents a novel metal-supported bilayer lipid membrane (BLM) biosensor built on tyrosinase to quantitate phenol. The detection strategy is based on the enzyme-analyte initial association and not the commonly adopted monitoring of the redox cascade reactions; such an approach has not been proposed in the literature to date and offers many advantages for environmental monitoring with regard to sensitivity, selectivity, reliability and assay simplicity. The phenol sensor developed herein showed good analytical and operational characteristics: the detection limit (signal-to-noise ratio = 3) was 1.24 pg/mL and the sensitivity was 33.45 nA per pg/mL phenol concentration. The shelf life of the tyrosinase sensor was 12 h and the lifetime (in consecutive assays) was 8 h. The sensor was reversible with bathing at pH 8.5 and could be used for eight assay runs in consecutive assays. The validation in real water samples showed that the sensor could reliably detect 2.5 ppb phenol in tap and river water and 6.1 ppb phenol in lake water, without sample pretreatment. The prospects and applicability of the proposed biosensor and the underlying technology are also discussed.

Recent Developments in Plasmonic Sensors of Phenol and Its Derivatives

Many scientists are increasingly interested in on-site detection methods of phenol and its derivatives because these substances have been universally used as a significant raw material in the industrial manufacturing of various chemicals of antimicrobials, anti-inflammatory drugs, antioxidants, and so on. The contamination of phenolic compounds in the natural environment is a toxic response that induces harsh impacts on plants, animals, and human health. This mini-review updates recent developments and trends of novel plasmonic resonance nanomaterials, which are assisted by various optical sensors, including colorimetric, fluorescence, localized surface plasmon resonance (LSPR), and plasmon-enhanced Raman spectroscopy. These advanced and powerful analytical tools exhibit potential application for ultrahigh sensitivity, selectivity, and rapid detection of phenol and its derivatives. In this report, we mainly emphasize the recent progress and novel trends in the optical sensors of phenolic compounds. The applications of Raman technologies based on pure noble metals, hybrid nanomaterials, and metal–organic frameworks (MOFs) are presented, in which the remaining establishments and challenges are discussed and summarized to inspire the future improvement of scientific optical sensors into easy-to-operate effective platforms for the rapid and trace detection of phenol and its derivatives.

Engineering of physical properties of spray-deposited nanocrystalline Sb2O3 thin films by phase transformation

Nanostructured Sb₂O₃ thin films have been deposited onto glass substrates by using the chemical spray pyrolysis technique, and the effect of precursor solution volume on the physical properties was investigated for the first time. The prepared films were characterized in detail by using x-ray diffraction, field-emission scanning electron microscopy with energy dispersive x-ray analysis (FESEM-EDAX), UV-vis absorption and transmission spectroscopy, Raman spectroscopy analysis and electrical resistivity measurement. X-ray diffraction analysis shows that the senarmontite cubic phase is completely transferred to the valentinite orthorhombic phase as the precursor solution volume is increased. This phase transformation as a function of precursor volume is discussed in detail. The FESEM-EDAX analysis reconfirms the phase change showing well-defined nano-dimensional cubic hexagonal and orthorhombic octahedral morphologies with excellent stoichiometry. The optical property studies show that the bandgap energy of Sb₂O₃ varies from 3.43-3.98 eV as a function of precursor quantity. The as-grown Sb₂O₃ thin films are semiconducting in nature. The measured values of electrical resistivity and activation energy are found to be dependent on the spray solution volume. The electrical resistivity of deposited Sb₂O₃ thin films shows variation from 26.15 × 10²-34.27 × 10² Ω cm and the activation energy of the films is in the order of 0.763-0.773 eV.

An Electrochemical Approach for the Selective Detection of Cancer Metabolic Creatine Biomarker with Porous Nano-Formulated CMNO Materials Decorated Glassy Carbon Electrode

The facile wet-chemical technique was used to prepare the low-dimensional nano-formulated porous mixed metal oxide nanomaterials (CuO.Mn2O3.NiO; CMNO NMs) in an alkaline medium at low temperature. Detailed structural, morphological, crystalline, and functional characterization of CMNO NMs were performed by X-ray photoelectron spectroscopy (XPS), powder X-ray diffraction (XRD), ultraviolet-visible spectroscopy (UV-vis), Fourier-transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FESEM), and energy-dispersive X-ray spectroscopy (EDS) analyses. An efficient and selective creatine (CA) sensor probe was fabricated by using CMNO NMs decorated onto glassy carbon electrode (GCE) as CMNO NMs/GCE by using Nafion adhesive (5% suspension in ethanol). The relation of current versus the concentration of CA was plotted to draw a calibration curve of the CMNO NMs/GCE sensor probe, which was found to have a very linear value (r2 = 0.9995) over a large dynamic range (LDR: 0.1 nM~0.1 mM) for selective CA detection. The slope of LDR by considering the active surface area of GCE (0.0316 cm2) was applied to estimate the sensor sensitivity (14.6308 µAµM-1 cm-2). Moreover, the detection limit (21.63 ± 0.05 pM) of CMNO MNs modified GCE was calculated from the signal/noise (S/N) ratio at 3. As a CA sensor probe, it exhibited long-term stability, good reproducibility, and fast response time in the detection of CA by electrochemical approach. Therefore, this research technique is introduced as a promising platform to develop an efficient sensor probe for cancer metabolic biomarker by using nano-formulated mixed metal oxides for biochemical as well as biomedical research for the safety of health care fields.

Photocatalysis, photoinduced enhanced anti-bacterial functions and development of a selective m-tolyl hydrazine sensor based on mixed Ag·NiMn2O4 nanomaterials

In this work, a tri-metal based nanocomposite was synthesized and characterized. A detailed investigation of the photocatalytic dye degradation efficiency of the nanocomposite under visible light showed promising results in a wide pH range, both acidic and basic medium. Studies on anti-bacterial activity against seven pathogenic bacteria, including both Gram positive and Gram negative species, were conducted in the presence and absence of light and compared with the standard antibiotic gentamicin. The minimum inhibitory concentration (MIC) values of Ag·NiMn2O4 against multidrug-resistant (MDR) pathogens ranged from 0.008 to 0.65 μg μL-1, while the minimum bactericidal concentration (MBC) was found to be 0.0016 μg μL-1. The nanomaterial, Ag·NiMn2O4 was deposited onto the surface of a glassy carbon electrode (GCE; 0.0316 cm2) as a thin film to fabricate the chemical sensor probe. The proposed sensor showed linear current (vs. concentration) response to m-THyd (m-tolyl hydrazine) from 1.0 pM to 0.01 mM, which is denoted as the linear dynamic range (LDR). The estimated sensitivity and detection limit of the m-THyd sensor were found to be 47.275 μA μM-1 cm-2 and 0.97 ± 0.05 pM, respectively. As a potential sensor, it is reliable due to its good reproducibility, rapid response, higher sensitivity, working stability for long duration and efficiency in the analysis of real environmental samples.

Facile fabrication of hierarchical p-Ag2O/n-Nb2O5 heterojunction microspheres with enhanced visible-light photocatalytic activity

Constructing p-n heterojunction is an efficient strategy to improve the photocatalytic efficiency. Here, we report a hierarchical Ag2O/Nb2O5 heterojunction composite as a novel and efficient visible-light driven photocatalyst. Hierarchical Nb2O5 microspheres were prepared by a hydrothermal method, and then the in situ growth of Ag2O nanoparticles on their surfaces was realized by a simple deposition method. Structural and textural features of the Ag2O/Nb2O5 composites were investigated, revealing that Ag2O nanoparticles were well distributed on the surface of Nb2O5 microspheres. Photocatalytic degradation of rhodamine B (RhB) was significantly enhanced by Ag2O/Nb2O5 photocatalysts under visible light. The optimal Ag/Nb molar ratio was determined to be 0.15 : 1, which yielded a 21.8 times faster degradation rate constant than plain Nb2O5 microspheres and had excellent stability for at least 4 catalytic cycles. The superior photocatalytic performance of Ag2O/Nb2O5 photocatalyst can be ascribed to the hierarchical superstructure as well as the heterojunction between Ag2O and Nb2O5, which facilitated the separation of photogenerated charge carriers. This work has potential application in the future for solving environmental pollution.

Enhanced visible light-mediated photocatalysis, antibacterial functions and fabrication of a 3-chlorophenol sensor based on ternary Ag2O·SrO·CaO

A novel multi-metal oxide nanocomposite, Ag2O·SrO·CaO, was synthesized by a facile co-precipitation method followed by calcinations. The synthesized nanocomposite was characterized by XRD, FESEM, EDS, TEM, FTIR spectroscopy and photoluminescence (PL) spectroscopy. The composite showed enhanced photocatalytic activity under visible light irradiation and excellent anti-bacterial performance against both Gram-positive and Gram-negative bacteria. Here, the synthesized Ag2O·SrO·CaO nanomaterials were deposited on a glassy carbon electrode (GCE) in the form of a thin film to fabricate the desired electrochemical sensor and subjected to I-V analysis of 3-chlorophenol (3-CP) in a phosphate buffer solution (PBS). A calibration curve was plotted from the linear relation of current versus concentration and used to calculate the sensitivity (8.9684 μA μM-1 cm-2), linear dynamic range (LDR, 0.1 nM to 0.01 mM) and lower limit of detection (DL, 97.12 ± 4.86 pM). The analytical parameters of the sensor such as response time, reproducibility and long-term stability in the detection of 3-CP were reliable. Finally, it was used to analyze real samples collected from various environmental sources and found to be acceptable.

Facile and efficient 3-chlorophenol sensor development based on photolumenescent core-shell CdSe/ZnS quantum dots

Quantum dots (QDs) are semiconducting inorganic nanoparticles, tiny molecules of 2-10 nm sizes to strength the quantum confinements of electrons. The QDs are good enough to emit light onto electrons for exciting and returning to the ground state. Here, CdSe/ZnS core/shell QDs have been prepared and applied for electrochemical sensor development in this approach. Flat glassy carbon electrode (GCE) was coated with CdSe/ZnS QDs as very thin uniform layer to result of the selective and efficient sensor of 3-CP (3-chlorophenol). The significant analytical parameters were calculated from the calibration plot such as sensitivity (3.6392 µA µM-1 cm-2) and detection limit (26.09 ± 1.30 pM) with CdSe/ZnS/GCE sensor probe by electrochemical approach. The calibration curve was fitted with the regression co-efficient r2 = 0.9906 in the range of 0.1 nM ∼ 0.1 mM concentration, which denoted as linear dynamic range (LDR). Besides these, it was performed the reproducibility in short response time and successfully validated the fabricated sensor for 3-CP in the real environmental and extracted samples. It is introduced as a noble route to detect the environmental phenolic contaminants using CdSe/ZnS QDs modified sensor by electrochemical method for the safety of healthcare and environmental fields at broad scales.

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.

Assessment of environmentally unsafe pollutants using facile wet-chemically prepared CeO2–ZrO2 nanocomposites by the electrochemical approach

Selective and sensitive 4-methoxyphenol chemical sensor was developed with a co-doped CeO₂–ZrO₂ nanocomposite modified glassy carbon electrode as a sensor probe by electrochemical approach for the safety of environmental and ecological fields in broad scales.

Enzyme-free detection of uric acid using hydrothermally prepared CuO·Fe2O3 nanocrystals

Copper oxide doped iron oxide nanocrystals (CuO·Fe₂O₃ NCs) were prepared using a simple hydrothermal technique at low temperature in an alkaline medium.

3-Methoxyphenol chemical sensor fabrication with Ag2O/CB nanocomposites

The proposed chemical sensor based on Ag₂O/CB nanocomposites is developed by electrochemical approach for the detection of hazardous selective 3-methoxyphenol chemical sensor for the safety of the environment sector in a broad scale.

Synthesis of novel pyrazole incorporating a coumarin moiety (PC) for selective and sensitive Co2+ detection

An efficient regioselective synthesis of a novel pyrazole derivative containing a coumarin moiety was achieved, which was electrodeposited as PC/Nafion/GCE sensor probe to detect the selective Co²⁺ ions for the safety of environment and healthcare fields.

Detection of uric acid based on doped ZnO/Ag2O/Co3O4 nanoparticle loaded glassy carbon electrode

Highly sensitive and selective uric acid sensor was fabricated using facile wet-chemically prepared ternary doped ZnO/Ag₂O/Co₃O₄ nanoparticles onto glassy carbon electrode by electrochemical approach, which introduced a prospective and reliable route to the future development of enzyme-free sensor by doped nanomaterials in broad scales.

Development of highly sensitive 1,4-dioxane sensor with semiconductor NiO-doped Nd2O3 nanostructures by electrochemical approach

In this approach, selective and sensitive 1,4-dioxane sensor probe was developed based on facile NiO@Nd₂O₃ nanocomposites embedded GCE for the safety management of environment and health care fields at a large scale.