Review—Three dimensional zinc oxide nanostructures as an active site platform for biosensor: Recent trend in healthcare diagnosis

Morphology effect is one of the essential factors that influence the performance of electrochemical biosensors based on ZnO nanostructures. These nanostructures are characterized by anisotropic growth with different dimensionalities such as zerodimensional, one-dimensional, and two-dimensional. More interestingly, when combining each dimension into another advanced dimensionality, i.e. the three-dimensional (3-D), exceptional properties can be generated that are not otherwise found in low dimensionalities. The outstanding popularity of 3-D ZnO stems from many factors, with one of the most important being its synergic advantages from its low dimensional sub-unit and the additional surface area of the 3-D structure due to an increased geometric volume. This review briefly describes the principles and growth mechanism factors of 3-D ZnO via solution-based approaches and additional advanced methods. The paper further expands on the latest advancement of research into the 3-D ZnO nanostructure-based electrochemical biosensors to detect biomolecules that harm humankind. We also discussed the analytical performance of these biosensors using different nanocomposite materials. Additionally, limitations and suggestions on particular sensing works are proposed. Lastly, the five-year progress in research into 3-D ZnO-based electrochemical biosensors’ performance in healthcare diagnosis is compared and future challenges presente

Green synthesis of Au coated on ZnO nanoparticles using orange peel extract and its application for electrochemical detection of formaldehyde

We report the facile preparation of Au coated ZnO nanoparticles via a two-step green synthesis route. The aqueous of orange peel extract (OPE) was used both as biocomplexing and bioreducing agents, while the Zn(NO3)2 and HAuCl4 were employed as precursors. Initially, OPE was prepared to synthesize the ZnONPs, followed by the reduction of HAuCl4, generating Au coated on ZnO nanoparticles (Au/ZnONPs). The IR spectra at around 438.95 cm-1 confirmed the presence of Zn-O absorption in the nanoparticles, while it was not observed in the OPE. Further characterization using XRD and SEM-EDX indicated that the spherical of Au was successfully coated on the sponge-like structure of ZnO with the crystalline size of ZnONPs and Au/ZnONPs were 21.30 and 26.67 nm, respectively.  The modified Au/ZnONPs on graphite paste electrode showed the excellent electrochemical detection of formaldehyde solution by the linearity range from 1 to 100 mM (R2=0.9945) with LOD of 10.27 mM and RSD of 0.39%. In addition, the modified electrode showed high selectivity toward formaldehyde, instead of ethanol

Rapid response analytical systems based on the direct coupling of flat supports and instrumental techniques

En las últimas décadas, la Química Analítica ha estudiado en profundidad el desarrollo de metodologías capaces de proporcionar resultados fiables de manera rápida para así responder a la creciente demanda informativa de la sociedad actual. En este contexto, la etapa de tratamiento de muestra se ha visto directamente afectada debido al tiempo que requiere y, además, por ser la principal fuente de error como consecuencia del alto grado de participación humana. La simplificación, miniaturización y automatización han sido las principales fuerzas impulsoras de la evolución del tratamiento de muestra en estos años. La aplicación de estas tres tendencias ha dado lugar a la aparición de las técnicas de microextracción. La reducción del consumo de reactivos, disolventes y energía, así como de los residuos generados, responden al compromiso social y medioambiental de la Química Verde y, al mismo tiempo, contribuyen al desarrollo de metodologías simples capaces de proporcionar resultados de calidad en un tiempo reducido. Esta simplificación engloba, asimismo, a los materiales sorbentes empleados en las técnicas de microextracción. En esta línea, los dispositivos analíticos basados en papel han despertado un gran interés debido a las múltiples ventajas de este material como fase sorbente, entre las que destacan su flexibilidad, porosidad y bajo coste. Asimismo, en los últimos años, la modificación del papel con distintos materiales ha sido una tendencia estable que ha derivado en la mejora de la versatilidad de este soporte. La modificación del papel con polímeros o nanomateriales ha hecho posible el desarrollo de soportes planos con una elevada área superficial capaces de interaccionar con una gran variedad de analitos. No obstante, los procedimientos llevados a cabo para la modificación del papel a menudo son complicados y requieren un control muy estricto de las condiciones experimentales. Por este motivo, es necesario buscar alternativas capaces de solventar estas dificultades. La simplificación de la etapa de tratamiento de muestra no supondría un gran avance si las técnicas instrumentales empleadas para la determinación de los analitos no estuviesen igualmente influenciadas por esta tendencia. En este sentido, los soportes basados en papel han sido también muy útiles debido a su fácil manipulación y acoplamiento con técnicas instrumentales, como las técnicas espectroscópicas (fluorimetría, Raman, etc.) o la espectrometría de masas en la modalidad de paper-spray. Teniendo en cuenta lo anteriormente expuesto, el objetivo principal de la Tesis Doctoral presentada en esta Memoria es el desarrollo de sistemas analíticos de respuesta rápida basados en el acoplamiento directo de soportes planos basados en papel con técnicas instrumentales, tales como la fluorimetría, la espectroscopia Raman y/o la espectrometría de masas. De este objetivo principal, surgen los siguientes objetivos específicos: • Síntesis de soportes planos basados en papel compatibles con espectrometría de masas en la modalidad de infusión directa. Este objetivo se afronta en los Bloques II y III con el desarrollo de dos soportes planos basados en papel. En primer lugar, se ha explotado la capacidad sorbente intrínseca del papel (Capítulo 2). En el segundo caso, se ha modificado papel de filtro con un polímero de impresión molecular para mejorar la selectividad en el aislamiento de los analitos (Capítulo 5). • Síntesis de soportes planos basados en papel compatibles con técnicas espectroscópicas. En el Capítulo 3 de la Memoria se describe el empleo de sorbentes con una alta selectividad en diversas técnicas instrumentales. Por otro lado, se ha desarrollado un sustrato basado en papel modificado con un polímero de impresión molecular y se ha propuesto su acoplamiento con fluorimetría (Capítulo 4). • Síntesis de soportes planos basados en papel duales compatibles tanto con técnicas espectroscópicas como con espectrometría de masas. Esta investigación se desarrolla en el Bloque IV de la Memoria, donde se describen las tendencias sobre las membranas modificadas con nanomateriales (Capítulo 6). Además, se llevó a cabo la modificación de un sustrato basado en papel con nanoflores de plata para la determinación de ketoprofeno en muestra de saliva mediante espectroscopia Raman amplificada en superficie y espectrometría de masas ambiental en la modalidad de paper-spray (Capítulo 7). Por otro lado, también se han desarrollado los siguientes objetivos transversales durante el transcurso de la Tesis Doctoral: • Caracterización de los soportes sintetizados mediante diversas técnicas instrumentales. • Aplicación de los procedimientos desarrollados en el análisis de alimentos y muestras biológicas.In the last decades, the development of methodologies able to provide rapid and reliable results has been deeply investigated in order to address the growing information demand of modern society. In this context, the sample preparation field is greatly concerning, since it is one of the most time-consuming steps and the main source of errors in the analytical procedure, due to the high level of human intervention. Simplification, automation and miniaturization have been the three main tendencies followed in the sample preparation field in the past years, leading to the rise of the microextraction techniques. Furthermore, the decrease of reagents, solvents and energy consumption agrees with the Green Chemistry principles and at the same time contributes to the development of methodologies capable of providing high-quality results in a shorter time. The simplification also involves the materials used in the microextraction techniques. Paper-based analytical devices have emerged as a very promising material due to the advantages of paper as a sorbent, e.g., flexibility, porosity or costeffectiveness. Likewise, the chemical modification of paper with different materials is a steady trend that has led to the increase of the versatility of this support. The modification of paper with polymers or nanomaterials has enabled the synthesis of flat supports with a high surface area able to interact with a wide variety of analytes. However, the procedures employed to carry out these modifications are usually tedious, and a strict control of the experimental conditions is mandatory. For this reason, it is of high importance searching for alternative methods that can overcome this drawback. The simplification of the sample preparation step must consider not only the materials used, but also the instrumental techniques employed for the determination of the analytes. In this sense, paper-based analytical devices have been really useful due to their easy handling and coupling to instrumental techniques, such as spectroscopic techniques or paper-spray mass spectrometry. Based on the foregoing, the foremost aim of this Doctoral Thesis is the development of rapid response analytical systems based on the coupling of paper-based flat supports and instrumental techniques, such as fluorimetry, Raman spectroscopy or mass spectrometry, together with substrates that can be simultaneously employed in different techniques. The specific objectives derived from this general objective are as follows: • Synthesis of paper-based flat supports compatible with direct infusion mass spectrometry. This research is detailed in Blocks II and III, where two paperbased flat supports are developed. On the one hand, the intrinsic sorbent capacity of non-modified cellulose was exploited in Chapter 2. On the other hand, the obtention of a molecularly imprinted paper is explained in Chapter 5 of this Doctoral Thesis. • Synthesis of paper-based flat supports compatible with spectroscopic techniques. The employment of selectivity enhanced sorbents with different instrumental techniques is described in Chapter 3 of this Doctoral Thesis. Furthermore, a molecularly imprinted paper-based analytical device was developed and combined with fluorimetry (Chapter 4). • Synthesis of dual paper-based flat supports compatible with both spectroscopic techniques and mass spectrometry. The results of this study are shown in Block IV, where the current trends about particle loaded membranes are firstly described (Chapter 6). On the other hand, the development of a silver nanoflower-coated paper for the determination of ketoprofen in saliva samples via Surface-enhanced Raman spectroscopy and ambient pressure mass spectrometry was carried out (Chapter 7). Additionally, the following specific objectives have been treated transversally throughout the entire Doctoral Thesis: • Characterization of the supports obtained employing various instrumental techniques. • Application of the developed procedures in the analysis of food products and biological samples

Applications of Quantum Dots in the Food Industry

Quantum dots (QDs) are spherical particles with a size of <10 nm and, due to their unique properties, have good potential for use in the food industry. Among the various QDs, food industry researchers have highly regarded carbon quantum dots (CQDs) due to their nontoxicity and environmental friendliness. Food analysis is essential for quality assessment as well as safety control. In this regard, QDs-based fluorescence sensors can provide faster, more accurate, more sensitive, and cheaper analysis methods. The use of QDs to detect food additives, pathogens, heavy metals, nutrients, antibiotics, and insecticide residues is investigated in this chapter. QDs in packaging materials, due to their antioxidant, antimicrobial, and inhibitory properties, increase product shelf life, reduce the growth of microorganisms, improve mechanical properties, prevent gases and UV light, and reduce food waste. Their application in improved, active, intelligent, and bio-packaging will also be described. Then, their application in water treatment will be discussed. QDs, due to properties such as high aspect ratio, reactivity, electrostatic, hydrophilic, and hydrophobic interactions, have good potential for use in various water treatment methods, including membranes in filtration, adsorbents, and photocatalysts. Finally, their use to track protein will be investigated

Zinc Oxide Nanostructures: Synthesis and Characterization

The summary should be ca. 200 words; this text will present the book in all promotional forms (e.g. flyers). Please describe the book in straightforward and consumer-friendly terms. [Zinc oxide (ZnO) is a wide band gap semiconductor with an energy gap of 3.37 eV at room temperature. It has been used considerably for its catalytic, electrical, optoelectronic, and photochemical properties. ZnO nanomaterials, such as quantum dots, nanorods, and nanowires, have been intensively investigated for their important properties. Many methods have been described in the literature for the production of ZnO nanostructures, such as laser ablation, hydrothermal methods, electrochemical deposition, sol-gel methods, chemical vapour deposition, molecular beam epitaxy, the common thermal evaporation method, and the soft chemical solution method. The present Special Issue is devoted to the synthesis and characterization of ZnO nanostructures with novel technological applications.

Carbon-Based Nanomaterials for (Bio)Sensors Development

Carbon-based nanomaterials have been increasingly used in sensors and biosensors design due to their advantageous intrinsic properties, which include, but are not limited to, high electrical and thermal conductivity, chemical stability, optical properties, large specific surface, biocompatibility, and easy functionalization. The most commonly applied carbonaceous nanomaterials are carbon nanotubes (single- or multi-walled nanotubes) and graphene, but promising data have been also reported for (bio)sensors based on carbon quantum dots and nanocomposites, among others. The incorporation of carbon-based nanomaterials, independent of the detection scheme and developed platform type (optical, chemical, and biological, etc.), has a major beneficial effect on the (bio)sensor sensitivity, specificity, and overall performance. As a consequence, carbon-based nanomaterials have been promoting a revolution in the field of (bio)sensors with the development of increasingly sensitive devices. This Special Issue presents original research data and review articles that focus on (experimental or theoretical) advances, challenges, and outlooks concerning the preparation, characterization, and application of carbon-based nanomaterials for (bio)sensor development

The 1st International Electronic Conference on Chemical Sensors and Analytical Chemistry

The 1st International Electronic Conference on Chemical Sensors and Analytical Chemistry was held on 1–15 July 2021. The scope of this online conference was to gather experts that are well-known worldwide who are currently working in chemical sensor technologies and to provide an online forum for the presention and discussion of new results. Throughout this event, topics of interest included, but were not limited to, the following: electrochemical devices and sensors; optical chemical sensors; mass-sensitive sensors; materials for chemical sensing; nano- and micro-technologies for sensing; chemical assays and validation; chemical sensor applications; analytical methods; gas sensors and apparatuses; electronic noses; electronic tongues; microfluidic devices; lab-on-a-chip; single-molecule sensing; nanosensors; and medico-diagnostic testing

Anti-angiogenic and toxicity effects of Derris trifoliata extract in zebrafish embryo

Introduction: Derris trifoliata has been traditionally used as folk for the treatment of , rheumatic joints, diarrhoea, and dysmenorrhea, and rotenoids isolated from the plant have shown to exhibit anti-cancer properties. This study aimed to assess the toxicity effects and antiangiogenic activity of extract of Derris trifoliata on zebrafish embryo model. Materials and Methods: Zebrafihs embryos were treated with aqueous extract of Derris Trifoliata to evaluate its effects on angiogenesis and zebrafish-toxicity. Angiogenic response was analyzed using whole-mount alkaline phosphatase (AP) vessel staining on 72 hours post fertilization (hpf) zebrafish embryos. Results: 1.0 mg/ml concentration was toxic to zebrafish embryos and embryos exposed to concentrations at 0.5 mg/ml and below showed some malformations. Derris trifoliata aqueous extract also showed some anti-angiogenic activity in vivo in the zebrafish embryo model wereby at high concentration inhibited vessel formation in zebrafish embryo. Conclusions: The anti-angiogenic response of extract of Derris trifoliata in zebrafish in vivo model suggest its therapeutic potential as anti-cancer agent

A Zinc Oxide Nanoflower-Based Electrochemical Sensor for Trace Detection of Sunset Yellow

Zinc oxide nanoflower (ZnONF) was synthesized by a simple process and was used to construct a highly sensitive electrochemical sensor for the detection of sunset yellow (SY). Due to the large surface area and high accumulation efficiency of ZnONF, the ZnONF-modified carbon paste electrode (ZnONF/CPE) showed a strong enhancement effect on the electrochemical oxidation of SY. The electrochemical behaviors of SY were investigated using voltammetry with the ZnONF-based sensor. The optimized parameters included the amount of ZnONF, the accumulation time, and the pH value. Under optimal conditions, the oxidation peak current was linearly proportional to SY concentration in the range of 0.50–10 μg/L and 10–70 μg/L, while the detection limit was 0.10 μg/L (signal-to-noise ratio = 3). The proposed method was used to determine the amount of SY in soft drinks with recoveries of 97.5%–103%, and the results were in good agreement with the results obtained by high-performance liquid chromatography