N-Hydroxysuccinimide crosslinked graphene oxide–gold nanoflower modified SPE electrode for sensitive detection of chloramphenicol antibiotic

MOF-derived Co2CuS4 nanoparticles with gold-decorated reduced graphene oxide for electrochemical determination of chloramphenicol in real samples

Despite the beneficial effects of antibiotics such as chloramphenicol (CAP), they exert some destructive impacts on human health. We designed an electrochemical sensor based on reduced graphene oxide (rGO)/Au/Co2CuS4 nanohybrid for determination of CAP in food and biological samples. The Co2CuS4 was synthesized from binuclear metal-organic framework (CoCu-BDC) through a two-step process. Nanohybrid was characterized by X-ray photoelectron spectroscopy and transmission electron microscopy. The rGO/Au/Co2CuS4 provides more active sites and good electrical conductivity to reduce charge transfer resistance and improve the electrocatalytic activity for determination of CAP. The prepared sensor has a wide linear range from 7 to 141 nM with a limit of detection of 2.5 nM and a limit of quantification of 21.92 nM. It also provided high selectivity and repeatability with a relative standard deviation of 2.6%. Stability studies showed that the electrode has acceptable performance with efficiency of 95% after 33 days.

Graphene-based biosensors in milk analysis: A review of recent developments

Cow's milk, an excellent source of fat, protein, amino acids, vitamins and minerals, is currently one of the most consumed products worldwide. Contaminations originating from diverse sources, such as biological, chemical, and physical, cause dairy product quality problems and thus dairy-related disorders, raising public health issues. For this reason, legal authorities have deemed it necessary to classify certain contaminations in commercial milk and keep them within particular limitations; therefore, it is urgent to develop next-generation detection systems that can accurately identify just the contaminants of concern to human health. This review presents a detailed investigation of biosensors based on graphene and its derivatives, which offer superior sensitivity and selectivity, by classifying the contaminants under the headings biological, chemical, and physical, in cow's milk according to their sources. We reviewed the current status of graphene-based biosensor (GBs) technology for milk or dairy analysis, highlighting its strengths and weaknesses with the help of comparative studies, tables, and charts, and we put forward a novel perspective to handle future challenges.

Development of electrochemical sensors for quick detection of environmental (soil and water) NPK ions

All over the world, technology is becoming more and more prevalent in agriculture. Different types of instruments are already being used in this sector. For the time being, every farmer is trying to produce more crops on a piece of land. Eventually, soil loses its nutrients; however, to grow more crops, farmers use more fertilizers without knowing the proper conditions of the soil in real time. To overcome this issue, many scientists have recently focused on developing electrochemical sensors to detect macronutrients, i.e., nitrogen (N), phosphorus (P), and potassium (K), in soil or water rapidly. In this review, we focus mainly on the recent developments in electrochemical sensors used for the detection of nutrients (NPK) in different types of samples. As it is outlined, the use of smart and portable electrochemical sensors can be helpful for the reduction of excess fertilizer and can play a vital role in maintaining suitable conditions in soils and water. We are optimistic that this review can guide researchers in the development of a portable and suitable NPK detection system for soil nutrients.

Copper oxide nanoflowers/poly-l-glutamic acid modified advanced electrochemical sensor for selective detection of l-tryptophan in real samples

The main objective of this research work is to develop a low-cost sensor to detect l-tryptophan (L-tryp) in real sample medium based on a modified glassy carbon electrode. For this, copper oxide nanoflowers (CuONFs) and poly-l-glutamic acid (PGA) were used to modify GCE. The prepared NFs and PGA coated electrode was characterized using field emission scanning electron microscope (FE-SEM) with energy dispersive X-ray (EDX) and attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy. Furthermore, the electrochemical activity was performed by cyclic voltammetry (CV), differential pulse voltammetry (DPV) and electrochemical impedance spectroscopy (EIS). The modified electrode showed excellent electro-catalytic activity towards L-tryp detection in PBS solution at neutral pH 7.0. Based on the physiological pH condition, the proposed electrochemical sensor can detect L-tryp concentration with a linear range of 1.0 × 10^-4-8.0 × 10^-8 molL^-1 with having a detection limit of 5.0 × 10^-8 molL^-1 and sensitivity of 0.6μA/μMcm². The selectivity of L-tryp was tested with a mixture of salt and uric acid solution at the above conditions. Finally, this strategy demonstrated excellent recovery value in real sample analysis like milk and urine.

Simultaneous Dual-Sensing Platform Based on Aptamer-Functionalized DNA Hydrogels for Visual and Fluorescence Detection of Chloramphenicol and Aflatoxin M1

In this study, a chloramphenicol and aflatoxin M1 aptamer-functionalized DNA hydrogel was designed for the simultaneous detection of chloramphenicol and aflatoxin M1 for the first time. The acrydite-modified chloramphenicol aptamer sequence was used to synthesize the DNA hydrogel and for visual detection of chloramphenicol depending on the gel-to-sol transition of the target-responsive DNA hydrogel. The DNA hydrogel formulation was set as follows: 60% of each linear polyacrylamide-DNA conjugate and 40% of acrylamide and chloramphenicol aptamer/DNA strand-1 at a molar ratio of 1:1, and the lowest concentration of chloramphenicol leading to gel dissociation was 1.0 nM at 25 °C. Furthermore, the formalized aptamer-functionalized DNA hydrogel was used to detect aflatoxin M1 by measuring the recovery of the fluorescence signal that was quenched when the FAM-labeled aflatoxin M1 aptamer and BHQ1-labeled DNA strand-2 were hybridized to form a double-stranded DNA in the network of hydrogel. The detection platform was successfully applied to the detection of chloramphenicol and aflatoxin M1, both in aqueous solution and in milk. The aptamer-functionalized DNA hydrogel had detection (LOD) and quantification limits (LOQ) for aflatoxin M1 as 1.7 and 5.2 nM, respectively. Using two aptamer sequences with high affinity and specificity, the dual-sensing platform based on the DNA hydrogel achieved higher selectivity for chloramphenicol and aflatoxin M1, which demonstrated its potential as a reliable simultaneous detection platform against two different targets for monitoring food safety.

Carbon Nanomaterials-Based Screen-Printed Electrodes for Sensing Applications

Electrochemical sensors consisting of screen-printed electrodes (SPEs) are recurrent devices in the recent literature for applications in different fields of interest and contribute to the expanding electroanalytical chemistry field. This is due to inherent characteristics that can be better (or only) achieved with the use of SPEs, including miniaturization, cost reduction, lower sample consumption, compatibility with portable equipment, and disposability. SPEs are also quite versatile; they can be manufactured using different formulations of conductive inks and substrates, and are of varied designs. Naturally, the analytical performance of SPEs is directly affected by the quality of the material used for printing and modifying the electrodes. In this sense, the most varied carbon nanomaterials have been explored for the preparation and modification of SPEs, providing devices with an enhanced electrochemical response and greater sensitivity, in addition to functionalized surfaces that can immobilize biological agents for the manufacture of biosensors. Considering the relevance and timeliness of the topic, this review aimed to provide an overview of the current scenario of the use of carbonaceous nanomaterials in the context of making electrochemical SPE sensors, from which different approaches will be presented, exploring materials traditionally investigated in electrochemistry, such as graphene, carbon nanotubes, carbon black, and those more recently investigated for this (carbon quantum dots, graphitic carbon nitride, and biochar). Perspectives on the use and expansion of these devices are also considered.

Recent Advances in Metal Nanocomposite-Based Electrochemical (Bio)Sensors for Pharmaceutical Analysis

Rising rates of drug abuse and pharmaceutical pollution throughout the world as a consequence of increased drug production and utilization pose a serious risk to public health and to environmental integrity. It is thus critical that reliable analytical approaches to detecting drugs and their metabolites in a range of sample matrices be developed. Recent advances in the design of nanomaterial-based electrochemical sensors and biosensors have enabled promising new approaches to pharmaceutical analysis. In particular, the development of a range of novel metal nanocomposites with enhanced catalytic properties has provided a wealth of opportunities for the design of rapid and reliable platforms for the detection of specific pharmaceutical compounds. The present review provides a comprehensive overview of representative metal nanocomposites with synergistic properties and their recent (2017-2022) application in the context of electrochemical sensing as a means of detecting specific antibiotic, tuberculostatic, analgesic, antineoplastic, antipsychotic, and antihypertensive drugs. In discussing these applications, we further explore a variety of testing-related principles, fabrication approaches, characterization techniques, and parameters associated with the sensitivity and selectivity of these sensor platforms before surveying the future outlook regarding the fabrication of next-generation (bio)sensor platforms for use in pharmaceutical analysis.

A review on nanomaterial-based electrodes for the electrochemical detection of chloramphenicol and furazolidone antibiotics

To grow food for people, antibiotics were used, and these antibiotics can accumulate in the human body through food metabolism, which may have remarkably harmful effects on human health and safety. Therefore, low-cost sensors are needed for the detection of antibiotic residues in food samples. Recently, nanomaterial-based electrochemical sensors such as carbon nanoparticles, graphene nanoparticles, metal oxide nanoparticles, metal nanoparticles, and metal-organic nanostructures have been successfully used as sensing materials for the detection of chloramphenicol (CP) and furazolidone (FZ) antibiotics. However, additional efforts are still needed to fabricate effective multi-functional nanomaterial-based electrodes for the preparation of portable electrochemical sensor devices. The current review focuses on a quick introduction to CP and FZ antibiotics, followed by an outline of the current electrochemical analytical methods. In addition, we have discussed in-depth different nanoparticle supports for the electrochemical detection of CP and FZ in different matrices such as food, environmental, and biological samples. Finally, a summary of the current problems and future perspectives in this area are also highlighted.

Graphene-based electrochemical sensors for antibiotic detection in water, food and soil: A scientometric analysis in CiteSpace (2011-2021)

The residues of antibiotics in the environment pose a potential health hazard, so highly sensitive detection of antibiotics has always appealed to analytical chemists. With the widespread use of new low-dimensional materials, graphene-modified electrochemical sensors have emerged as an excellent candidate for highly sensitive detection of antibiotics. Graphene, its derivatives and its composites have been used in this field of exploration in the last decade. In this review, we have not only described the field using traditional summaries, but also used bibliometrics to quantify the development of the field. The literature between 2011 and 2021 was included in the analysis. Also, the sensing performance and detection targets of different sensors were compared. We were able to trace not only the flow of research themes, but also the future areas of development. Graphene is a material that has a high potential to be used on a large scale in the preparation of electrochemical sensors. How to design a sensor with selectivity and low cost is the key to bring this material from the laboratory to practical applications.

Past and Present of Electrochemical Sensors and Methods for Amphenicol Antibiotic Analysis

Amphenicols are broad-spectrum antibiotics. Despite their benefits, they also present toxic effects and therefore their presence in animal-derived food was regulated. Various analytical methods have been reported for their trace analysis in food and environmental samples, as well as in the quality control of pharmaceuticals. Among these methods, the electrochemical ones are simpler, more rapid and cost-effective. The working electrode is the core of any electroanalytical method because the selectivity and sensitivity of the determination depend on its surface activity. Therefore, this review offers a comprehensive overview of the electrochemical sensors and methods along with their performance characteristics for chloramphenicol, thiamphenicol and florfenicol detection, with a focus on those reported in the last five years. Electrode modification procedures and analytical applications of the recently described devices for amphenicol electroanalysis in various matrices (pharmaceuticals, environmental, foods), together with the sample preparation methods were discussed. Therefore, the information and the concepts contained in this review can be a starting point for future new findings in the field of amphenicol electrochemical detection.

Carbonaceous materials for removal and recovery of phosphate species: Limitations, successes and future improvement

The carbonaceous materials have gained significant interest for the phosphorus species remediation and recovery in the last decade. Carbonaceous materials present many unique features, such as cost effective, availability, environmentally friendly, and high removal efficiency that make them a promising adsorbent. In this review, the recent application of carbonaceous materials including activated carbon (AC), graphene and graphene oxide (GO), lignin, carbon nanotubes (CNTs), and gC₃N₄ for phosphate removal and recovery were comprehensively summarized. The kinetics and isotherm models, removal mechanisms, and effects of operating parameters are reported. The reusability, lifetime of carbonaceous materials, and impact of modification were also considered. The modified carbonaceous materials have significantly high phosphate adsorption capacity compared to unmodified adsorbents. Namely, MgO-functionalized lignin-based bio-charcoal exhibited a 906.8 mg g^-1 of capacity as the highest one among other reviewed materials. The modification of carbonaceous materials with various elements has been presented to improve the surface functional groups, surface area and charge, and pore volume and size. Among these loaded elements, iron has been effectively used to provide a prospect for magnetic recovery of the adsorbent as well as increase phosphate adsorption. Furthermore, the phosphate recovery methods, phosphate removal efficiency of carbonaceous materials, the limitations, important gaps in the literature, and future studies to enhance applicability of carbonaceous materials in real scale are also discussed.

Graphitic carbon nitride and APTES modified advanced electrochemical biosensor for detection of 17β-estradiol in spiked food samples

This work demonstrates a simple and inexpensive electrochemical biosensing pathway for selective and sensitive recognition of 17β-estradiol (E2) in environmental and food samples. The biosensing system is based on graphitic carbon nitride (g-C₃N₄) and a conductive polymer 3-aminopropyltriethoxysilane (APTES). The proposed biosensor shows the ability to detect E2 in attomolar levels within a wide linear logarithm concentration range of 1 × 10⁻⁶ to 1 × 10⁻¹⁸ mol L⁻¹ with a limit of detection (LOD) of 9.9 × 10⁻¹⁹ mol L⁻¹. The selectivity of the developed biosensor was confirmed by conducting the DPV of similarly structured hormones and naturally occurring substances. The proposed biosensor is highly stable and applicable to detect E2 in the presence of spiked food and environmental samples with satisfactory recoveries ranging from 95.1 to 104.8%. So, the designed electrochemical biosensor might be an effective alternative tool for the detection of E2 and other endogenous substances to attain food safety.

This work demonstrates a simple and inexpensive electrochemical biosensing pathway for selective and sensitive recognition of 17β-estradiol (E2) in environmental and food samples.

Novel label-free fluorescence aptasensor for chloramphenicol detection based on a DNA four-arm junction-assisted signal amplification strategy

A novel label-free fluorescence aptasensor was established for chloramphenicol (CAP) detection by DNA four-arm junction-assisted target recycling and SYBR Green I dye-aided fluorescence-signal amplification. The CAP aptamer was hybridized to its complementary strand (primer) to form a double-stranded primer/aptamer complex. In the presence of CAP, aptamers can specifically bind with CAP to dissociate primers, which can trigger the self-assembly of four hairpins to continuously generate DNA four-arm junctions. After digesting the excess hairpins using T7 exonuclease, SYBR Green I was inserted into the base pair-rich DNA four-arm junctions, which led to a significant increase in fluorescence intensity. Under optimal conditions, the developed aptasensor can detect CAP in a linear range of 1.0 pg mL^-1 to 10 ng mL^-1 with a detection limit of 0.72 pg mL^-1. The recovery rates in milk and honey ranged from 90.3% to 106.6%. Thus, the method shows substantial potential for CAP detection in food products.