Preparation of highly sensitive electrochemical sensor for detection of nitrite in drinking water samples

Nitrite is both an environmental contaminant and a food additive. Excessive intake of nitrites not only causes blood diseases, but also has the potential risk of causing cancer. Therefore, rapid detection of nitrite in water is necessary. In this work, we propose an electrochemical sensor for the sensing of nitrite. Glassy carbon electrodes modified with noble metal nanomaterials have been widely used in the preparation of sensors, but the surface properties of noble metals largely affect the sensing performance. This work proposes the biosynthesis of Au nanoparticles using the pollen extract of Lycoris radiata as a reducing agent. Flavonoids rich in pollen can be used as weak reducing agents for the reduction of chloroauric acid, and slowly synthesize uniformly dispersed Au nanoparticles. These Au nanoparticles do not agglomerate because they contain small biological molecules on the surface and can form a homogeneous sensing interface on the electrode surface. The electrochemical sensor assembled with biosynthesized Au nanoparticles provides linear detection of nitrite between 0.01 and 3.8 mM. The sensor also has excellent immunity to interference. In addition, the proposed sensor was also successfully used for the detection of nitrite in drinking water.

Electrochemical Sensors and Biosensors for the Analysis of Tea Components: A Bibliometric Review

Tea is a popular beverage all around the world. Tea composition, quality monitoring, and tea identification have all been the subject of extensive research due to concerns about the nutritional value and safety of tea intake. In the last 2 decades, research into tea employing electrochemical biosensing technologies has received a lot of interest. Despite the fact that electrochemical biosensing is not yet the most widely utilized approach for tea analysis, it has emerged as a promising technology due to its high sensitivity, speed, and low cost. Through bibliometric analysis, we give a systematic survey of the literature on electrochemical analysis of tea from 1994 to 2021 in this study. Electrochemical analysis in the study of tea can be split into three distinct stages, according to the bibliometric analysis. After chromatographic separation of materials, electrochemical techniques were initially used only as a detection tool. Many key components of tea, including as tea polyphenols, gallic acid, caffeic acid, and others, have electrochemical activity, and their electrochemical behavior is being investigated. High-performance electrochemical sensors have steadily become a hot research issue as materials science, particularly nanomaterials, and has progressed. This review not only highlights these processes, but also analyzes and contrasts the relevant literature. This evaluation also provides future views in this area based on the bibliometric findings.

Application of Solid-state Electrochemical Analysis in Ancient Ceramic Identification and Characterization: A Review

Background:

Ceramics can reflect ancient technology and art, therefore, it has a very important position in archaeology. However, it is far from enough just to study the shape of pottery and porcelain. It is necessary to use advanced scientific and technological means to conduct a comprehensive analysis of pottery and porcelain, so as to study the information hidden deep in the remains of ceramic objects.

Methods:

The solid voltammetric method can be used to obtain information about the composition of materials used in ancient ceramics. This new method can be applied to insoluble solids for example, providing qualitative and quantitative information and structural information with little soluble solids. The method requires only ng-μg sample.

Results:

In this review, we first describe the development of solid-state voltammetric method and our work in this field. Then, we describe in detail the application of this method in archaeology, especially in the analysis of ceramics. Finally, we describe the analytical applications of other electrochemical techniques for ceramics analysis.

Conclusion:

Due to the low demand for samples and the high-cost performance of analytical instruments, this method has been widely studied in Europe. To sum up, we propose to establish a microsampling method for ancient ceramics. A new method for the protection of fine ancient ceramics by the suitable carrier and the fixation on the surface of the electrode. These improvements can enable solid-state electroanalytical chemistry technology to achieve more comprehensive and accurate quantitative analysis of ancient ceramics particles. We also propose the current challenges and future directions of solid-state electroanalytical chemistry.

Evaluation of Peroxidase in Herbal Medicines Based on an Electrochemical Sensor

Peroxidases are species-specific. Differences in peroxidase can objectively reflect the genetics among species. The use of peroxidase to assist in species identification is relatively simple and effective. In this work, we proposed a graphene-modified electrode. This electrode can amplify the signal of electrocatalytic reduction of hydrogen peroxide. Since peroxidase can catalyze the reduction of hydrogen peroxide, this signal can be used as an indicator to demonstrate the content of peroxidase in different plant tissues. Twelve herbal medicines were selected for our study. The results show that this electrochemical-based detection technique was comparable to colorimetric method in terms of accuracy.

Synthesis of Zinc Oxide Nanoparticles Using Rubus fairholmianus Root Extract and Their Activity against Pathogenic Bacteria

Recently, the biosynthesis of zinc oxide nanoparticles (ZnO NPs) from crude extracts and phytochemicals has attracted much attention. Green synthesis of NPs is cost-effective, eco-friendly, and is a promising alternative for chemical synthesis. This study involves ZnO NPs synthesis using Rubus fairholmianus root extract (RE) as an efficient reducing agent. The UV spectrum of RE-ZnO NPs exhibited a peak at 357 nm due to intrinsic bandgap absorption and an XRD pattern that matches the ZnO crystal structure (JCPDS card no: 36-1451). The average particle size calculated from the Debye-Scherrer equation is 11.34 nm. SEM analysis showed that the RE-ZnO NPs spherical in shape with clusters (1-100 nm). The antibacterial activity of the NPs was tested against Staphylococcus aureus using agar well diffusion, minimum inhibitory concentration, and bacterial growth assay. The R. fairholmianus phytochemicals facilitate the synthesis of stable ZnO NPs and showed antibacterial activity.

An electrochemical sensor for high sensitive determination of lysozyme based on the aptamer competition approach

Protein is a kind of basic substance that constitutes a life body. The determination of protein is very important for the research of biology, medicine, and other fields. Lysozyme is relatively small and simple in structure among all kinds of proteins, so it is often used as a standard target detector in the study of aptamer sensor for protein detection. In this paper, a lysozyme electrochemical sensor based on aptamer competition mechanism is proposed. We have successfully prepared a signal weakening electrochemical sensor based on the lysozyme aptamer competition mechanism. The carboxylated multi-walled carbon nanotubes (MWCNTs) were modified on the glassy carbon electrode, and the complementary aptamer DNA with amino group was connected to MWCNTs. Because of the complementary DNA of daunomycin into the electrode, the electrochemical signal is generated. When there is a target, the aptamer binds to lysozyme with higher binding power, and the original complementary chain breaks down, resulting in the loss of daunomycin inserted into the double chain and the weakening of electrochemical signal. Differential pulse voltammetry was used to determine lysozyme, the response range was 1–500 nM, the correlation coefficient was 0.9995, and the detection limit was 0.5 nM. In addition, the proposed sensor has good selectivity and anti-interference.

Plant celluloses, hemicelluloses, lignins, and volatile oils for the synthesis of nanoparticles and nanostructured materials

A huge variety of plants are harvested worldwide and their different constituents can be converted into a broad range of bionanomaterials. In parallel, much research effort in materials science and engineering is focused on the formation of nanoparticles and nanostructured materials originating from agricultural residues. Cellulose (40-50%), hemicellulose (20-40%), and lignin (20-30%) represent major plant ingredients and many techniques have been described that separate the main plant components for the synthesis of nanocelluloses, nano-hemicelluloses, and nanolignins with divergent and controllable properties. The minor components, such as essential oils, could also be used to produce non-toxic metal and metal oxide nanoparticles with high bioavailability, biocompatibility, and/or bioactivity. This review describes the chemical structure, the physical and chemical properties of plant cell constituents, different techniques for the synthesis of nanocelluloses, nanohemicelluloses, and nanolignins from various lignocellulose sources and agricultural residues, and the extraction of volatile oils from plants as well as their use in metal and metal oxide nanoparticle production and emulsion preparation. Furthermore, details about the formation of activated carbon nanomaterials by thermal treatment of lignocellulose materials, a few examples of mineral extraction from agriculture waste for nanoparticle fabrication, and the emerging applications of plant-based nanomaterials in different fields, such as biotechnology and medicine, environment protection, environmental remediation, or energy production and storage, are also included. This review also briefly discusses the recent developments and challenges of obtaining nanomaterials from plant residues, and the issues surrounding toxicity and regulation.

Development of Electrochemical Oscillation Method for Identification of Prunus persica, Prunus davidiana, and Prunus armeniaca Nuts

In this work, an electrochemical oscillation system has been developed using the Belousov-Zhabotinsky reaction. The effect of the combination of each reagent, reaction temperature, and stirring speed on the induction period, oscillating period, and oscillating life were optimized. The nuts of Prunus persica, Prunus davidiana, and Prunus armeniaca have been widely used for medical purposes. The proposed electrochemical oscillation system was then used for the identification of P. persica, P. davidiana, and P. armeniaca. Three nuts exhibited very different electrochemical oscillation profiles. The dendrogram was divided into three main principal infrageneric clades. Each cluster only contains one species, suggesting that no outlier was observed in this study. Based on the discussed results, we proposed a simple method for herbal medicine identification.

An Electrochemical Sandwich Immunosensor Based on Signal Amplification Technique for the Determination of Alpha-Fetoprotein

The synthesis of Au nanocubes is used to label alpha-fetoprotein antibody (anti-AFP) and horseradish peroxidase (HRP) to form an immune complex for antibody detection. Graphene oxide-methylene blue-gold nanoparticles (GO-MB-AuNPs) nanocomposites were used as the immunosensing platform. This proposed sandwich-type immunoassay shows good performance. This method establishes a feasible amperometric immunoassay method for sensitive analysis of AFP in serum samples. Under the optimal experimental conditions, the DPV current response of the immunosensor is proportional to the logarithmic value of the AFP concentration. The linear detection range can achieve to 0.005–20 ng/mL with a detection limit of 1.5 pg/mL. The proposed immunosensor has good precision, selectivity and stability, and can be used for AFP determination in clinical tests.

Role of gold nanoparticles in advanced biomedical applications

Gold nanoparticles (GNPs) have generated keen interest among researchers in recent years due to their excellent physicochemical properties. In general, GNPs are biocompatible, amenable to desired functionalization, non-corroding, and exhibit size and shape dependent optical and electronic properties. These excellent properties of GNPs exhibit their tremendous potential for use in diverse biomedical applications. Herein, we have evaluated the recent advancements of GNPs to highlight their exceptional potential in the biomedical field. Special focus has been given to emerging biomedical applications including bio-imaging, site specific drug/gene delivery, nano-sensing, diagnostics, photon induced therapeutics, and theranostics. We have also elaborated on the basics, presented a historical preview, and discussed the synthesis strategies, functionalization methods, stabilization techniques, and key properties of GNPs. Lastly, we have concluded this article with key findings and unaddressed challenges. Overall, this review is a complete package to understand the importance and achievements of GNPs in the biomedical field.