Rational Design of Triboelectric Materials and Devices for Self-Powered Food Sensing

Against the backdrop of rapid advancements in 5G and Internet of Things (IoT) technologies, there is an urgent need to upgrade food sensing systems to achieve automation, digitalization, and intelligence. However, this transformation process faces numerous challenges. Triboelectric nanogenerators (TENGs), as an emerging energy conversion and sensing technology, play a crucial role in this context. They not only provide power to functional devices but also serve as sensors in multifunctional self-powered food sensing systems, capable of detecting various physical and chemical information. This review explores the development of TENGs in the field of food sensing, focusing on the working principles of their self-powered sensing. The review also systematically organizes and classifies the material and device designs used for TENGs in various food applications. Based on the performance of TENGs, a detailed introduction is provided on the specific applications of self-powered food sterilization, self-powered food quality monitoring, and self-powered taste sensing in the field of food safety. Finally, this paper discusses the challenges and corresponding strategies of TENGs in the food sensing field. The aim is to further promote unmanned and smart services and management in the food sector and to provide new research perspectives.

Target Recognition-Triggered Interfacial Electron Transfer Model: Toward Signal-On Photoelectrochemical Aptasensing for Efficient Detection of Staphylococcus aureus Using Ti3C2Tx-Au NBPs/ZnO NR Composites

Staphylococcus aureus (S. aureus) is one of the most common foodborne pathogens worldwide, which poses a great threat to public health. It is of utmost importance to develop rapid, simple, and sensitive methods for the determination of S. aureus. A signal-on photoelectrochemical (PEC) aptasensor is constructed herein based on titanium carbide (Ti3C2Tx)-Au nanobipyramids (NBPs)/ZnO nanoarrays (NRs). The reliability and capability of the PEC aptasensor make it suitable for the sensitive and selective determination of S. aureus. First, the electrostatically self-assembled Ti3C2Tx-Au NBP nanomaterial was coated on the ZnO NR surface by a spin-coating method. On the one hand, Ti3C2Tx-Au NBPs can broaden the spectral absorption of ZnO NRs, resulting in Ti3C2Tx-Au NBPs/ZnO NR composites that exhibit a wide range of absorption from the ultraviolet to the infrared region. On the other hand, Ti3C2Tx can reduce the agglomeration of nanoparticles, while Au NBPs can effectively fix the aptamer through the Au-S bond. Specifically, the experimental results show that when S. aureus is present, the Au NBPs-aptamer-S. aureus complex is shed from the electrode surface, altering the interfacial electron transfer model and reducing the steric hindrance. Consequently, an amplified photocurrent signal for the quantitative determination of S. aureus is obtained. Under optimal experimental conditions, a linear correlation is observed between the current response of the aptasensor and the logarithm of the S. aureus concentration (ranging from 1.0 to 1.0 × 106 CFU/mL), with an impressive detection limit as low as 0.5 CFU/mL. Furthermore, the aptasensor has been successfully employed for the detection of S. aureus in milk, with the recovery of 93.0%-99.0%. Hence, this research offers a novel approach for the detection of foodborne pathogens and other noxious substances.

Red and near-infrared light-activated photoelectrochemical nanobiosensors for biomedical target detection

Photoelectrochemical (PEC) nanobiosensors integrate molecular (bio)recognition elements with semiconductor/plasmonic photoactive nanomaterials to produce measurable signals after light-induced reactions. Recent advancements in PEC nanobiosensors, using light-matter interactions, have significantly improved sensitivity, specificity, and signal-to-noise ratio in detecting (bio)analytes. Tunable nanomaterials activated by a wide spectral radiation window coupled to electrochemical transduction platforms have further improved detection by stabilizing and amplifying electrical signals. This work reviews PEC biosensors based on nanomaterials like metal oxides, carbon nitrides, quantum dots, and transition metal chalcogenides (TMCs), showing their superior optoelectronic properties and analytical performance for the detection of clinically relevant biomarkers. Furthermore, it highlights the innovative role of red light and NIR-activated PEC nanobiosensors in enhancing charge transfer processes, protecting them from biomolecule photodamage in vitro and in vivo applications. Overall, advances in PEC detection systems have the potential to revolutionize rapid and accurate measurements in clinical diagnostic applications. Their integration into miniaturized devices also supports the development of portable, easy-to-use diagnostic tools, facilitating point-of-care (POC) testing solutions and real-time monitoring.

A competitive-type photoelectrochemical aptasensor for 17 beta-estradiol detection in microfluidic devices based on a novel Au@Cd:SnO2/SnS2 nanocomposite

A competitive-type photoelectrochemical (PEC) aptasensor coupled with a novel Au@Cd:SnO2/SnS2 nanocomposite was designed for the detection of 17β-estradiol (E2) in microfluidic devices. The designed Au@Cd:SnO2/SnS2 nanocomposites exhibit high photoelectrochemical activity owing to the good matching of cascade band-edge and the efficient separation of photo-generated e-/h+ pairs derived from the Cd-doped defects in the energy level. The Au@Cd:SnO2/SnS2 nanocomposites were loaded into carbon paste electrodes (CPEs) to immobilize complementary DNA (cDNA) and estradiol aptamer probe DNA (E2-Apt), forming a double-strand DNA structure on the CPE surface. As the target E2 interacts with the double-strand DNA, E2-Apt is sensitively released from the CPE, subsequently increasing the photocurrent intensity due to the reduced steric hindrance of the electrode surface. The competitive-type sensing mechanism, combined with high PEC activity of the Au@Cd:SnO2/SnS2 nanocomposites, contributed to the rapid and sensitive detection of E2 in a "signal on" manner. Under the optimized conditions, the PEC aptasensor exhibited a linear range from 1.0 × 10-13 mol L-1 to 3.2 × 10-6 mol L-1 and a detection limit of 1.2 × 10-14 mol L-1 (S/N = 3). Moreover, the integration of microfluidic device with smartphone controlled portable electrochemical workstation enables the on-site detection of E2. The small sample volume (10 µL) and short analysis time (40 min) demonstrated the great potential of this strategy for E2 detection in rat serum and river water. With these advantages, the PEC aptasensor can be utilized for point-of-care testing (POCT) in both clinical and environmental applications.

Veterinary Drug Residues in the Food Chain as an Emerging Public Health Threat: Sources, Analytical Methods, Health Impacts, and Preventive Measures

Veterinary medications are necessary for both contemporary animal husbandry and food production, but their residues can linger in foods obtained from animals and pose a dangerous human risk. In this review, we aim to highlight the sources, occurrence, human exposure pathways, and human health effects of drug residues in food-animal products. Following the usage of veterinary medications, pharmacologically active compounds known as drug residues can be found in food, the environment, or animals. They can cause major health concerns to people, including antibiotic resistance development, the development of cancer, teratogenic effects, hypersensitivity, and disruption of normal intestinal flora. Drug residues in animal products can originate from variety of sources, including water or food contamination, extra-label drug use, and ignoring drug withdrawal periods. This review also examines how humans can be exposed to drug residues through drinking water, food, air, and dust, and discusses various analytical techniques for identifying these residues in food. Furthermore, we suggest some potential solutions to prevent or reduce drug residues in animal products and human exposure pathways, such as implementing withdrawal periods, monitoring programs, education campaigns, and new technologies that are crucial for safeguarding public health. This review underscores the urgency of addressing veterinary drug residues as a significant and emerging public health threat, calling for collaborative efforts from researchers, policymakers, and industry stakeholders to develop sustainable solutions that ensure the safety of the global food supply chain.

Recent advances in photoelectrochemical platforms based on porous materials for environmental pollutant detection

Human health and ecology are seriously threatened by harmful environmental contaminants. It is essential to develop efficient and simple methods for their detection. Environmental pollutants can be detected using photoelectrochemical (PEC) detection technologies. The key ingredient in the PEC sensing system is the photoactive material. Due to the unique characteristics, such as a large surface area, enhanced exposure of active sites, and effective mass capture and diffusion, porous materials have been regarded as ideal sensing materials for the construction of PEC sensors. Extensive efforts have been devoted to the development and modification of PEC sensors based on porous materials. However, a review of the relationship between detection performance and the structure of porous materials is still lacking. In this work, we present an overview of PEC sensors based on porous materials. A number of typical porous materials are introduced separately, and their applications in PEC detection of different types of environmental pollutants are also discussed. More importantly, special attention has been paid to how the porous material's structure affects aspects like sensitivity, selectivity, and detection limits of the associated PEC sensor. In addition, future research perspectives in the area of PEC sensors based on porous materials are presented.

Recent Progress in Photoelectrochemical Sensing of Pesticides in Food and Environmental Samples: Photoactive Materials and Signaling Mechanisms

Pesticides have become an integral part of modern agricultural practices, but their widespread use poses a significant threat to human health. As such, there is a pressing need to develop effective methods for detecting pesticides in food and environmental samples. Traditional chromatography methods and common rapid detection methods cannot satisfy accuracy, portability, long storage time, and solution stability at the same time. In recent years, photoelectrochemical (PEC) sensing technology has gained attention as a promising approach for detecting various pesticides due to its salient advantages, including high sensitivity, low cost, simple operation, fast response, and easy miniaturization, thus becoming a competitive candidate for real-time and on-site monitoring of pesticide levels. This review provides an overview of the recent advancements in PEC methods for pesticide detection and their applications in ensuring food and environmental safety, with a focus on the categories of photoactive materials, from single semiconductor to semiconductor-semiconductor heterojunction, and signaling mechanisms of PEC sensing platforms, including oxidation of pesticides, steric hindrance, generation/decrease in sacrificial agents, and introduction/release of photoactive materials. Additionally, this review will offer insights into future prospects and confrontations, thereby contributing novel perspectives to this evolving domain.

Hair and Nail-On-Chip for Bioinspired Microfluidic Device Fabrication and Biomarker Detection

The advent of biosensors has tremendously increased our potential of identifying and solving important problems in various domains, ranging from food safety and environmental analysis, to healthcare and medicine. However, one of the most prominent drawbacks of these technologies, especially in the biomedical field, is to employ conventional samples, such as blood, urine, tissue extracts and other body fluids for analysis, which suffer from the drawbacks of invasiveness, discomfort, and high costs encountered in transportation and storage, thereby hindering these products to be applied for point-of-care testing that has garnered substantial attention in recent years. Therefore, through this review, we emphasize for the first time, the applications of switching over to noninvasive sampling techniques involving hair and nails that not only circumvent most of the aforementioned limitations, but also serve as interesting alternatives in understanding the human physiology involving minimal costs, equipment and human interference when combined with rapidly advancing technologies, such as microfluidics and organ-on-a-chip to achieve miniaturization on an unprecedented scale. The coalescence between these two fields has not only led to the fabrication of novel microdevices involving hair and nails, but also function as robust biosensors for the detection of biomarkers, chemicals, metabolites and nucleic acids through noninvasive sampling. Finally, we have also elucidated a plethora of futuristic innovations that could be incorporated in such devices, such as expanding their applications in nail and hair-based drug delivery, their potential in serving as next-generation wearable sensors and integrating these devices with machine-learning for enhanced automation and decentralization.

Advances in Bioelectrode Design for Developing Electrochemical Biosensors

The critical performance factors such as selectivity, sensitivity, operational and storage stability, and response time of electrochemical biosensors are governed mainly by the function of their key component, the bioelectrode. Suitable design and fabrication strategies of the bioelectrode interface are essential for realizing the requisite performance of the biosensors for their practical utility. A multifaceted attempt to achieve this goal is visible from the vast literature exploring effective strategies for preparing, immobilizing, and stabilizing biorecognition elements on the electrode surface and efficient transduction of biochemical signals into electrical ones (i.e., current, voltage, and impedance) through the bioelectrode interface with the aid of advanced materials and techniques. The commercial success of biosensors in modern society is also increasingly influenced by their size (and hence portability), multiplexing capability, and coupling in the interface of the wireless communication technology, which facilitates quick data transfer and linked decision-making processes in real-time in different areas such as healthcare, agriculture, food, and environmental applications. Therefore, fabrication of the bioelectrode involves careful selection and control of several parameters, including biorecognition elements, electrode materials, shape and size of the electrode, detection principles, and various fabrication strategies, including microscale and printing technologies. This review discusses recent trends in bioelectrode designs and fabrications for developing electrochemical biosensors. The discussions have been delineated into the types of biorecognition elements and their immobilization strategies, signal transduction approaches, commonly used advanced materials for electrode fabrication and techniques for fabricating the bioelectrodes, and device integration with modern electronic communication technology for developing electrochemical biosensors of commercial interest.

Self-powered biosensor using photoactive ternary nanocomposite: Testing the phospholipid content in rhodotorula glutinis oil

In the field of oil refining, the presence of excessive residual phosphorus in crude oil can significantly impact its quality, thereby emphasizing the necessity for compact and convenient testing equipment. This study primarily focuses on developing of self-powered biosensor (SPB) using immobilizing Choline Oxidase with a photoactive ternary nanocomposite complex (CHOx-BiOI-rGO-Fe3O4 NPs-ITO) as the anode and utilizing a Pt electrode as the cathode. The successful preparation of the ternary composite photoelectrode for the anode was confirmed through a range of characterization techniques, including X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Transmission electron microscopy (TEM), Scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), N2 absorption/desorption, Dynamic light scattering (DLS), and Ultraviolet-visible diffuse reflection spectrometer (UV-vis DRS). The electrochemical and photoelectrochemical properties were assessed using an electrochemical workstation, revealing a significant enhancement photoelectrical responsiveness attributed to the formation of heterojunction structures. The SPB exhibited a remarkable linear relationship between the instantaneous photocurrent and phosphatidylcholine (PC) concentration, with a regression equation of I (μA) = 39.62071C (mM) + 3.47271. The linear range covered a concentration range of 0.01-10 mM, and the detection limit (S/N = 3) was determined to be 0.008 mM. It demonstrated excellent reproducibility and storage stability, positioning it a promising alternative to High-performance liquid chromatography (HPLC) for accurate quantification of PC content in rhodotorula glutinis oil. The standard recovery PC content ranged from 98.48% to 103.53%, with a relative standard deviation (RSD) ranging from 1.4% to 2.4%. This research presents a convenient and precise detection device that has the potential to address the issue of lagging detection in the oil refining process.

Glyphosate Separating and Sensing for Precision Agriculture and Environmental Protection in the Era of Smart Materials

The present article critically and comprehensively reviews the most recent reports on smart sensors for determining glyphosate (GLP), an active agent of GLP-based herbicides (GBHs) traditionally used in agriculture over the past decades. Commercialized in 1974, GBHs have now reached 350 million hectares of crops in over 140 countries with an annual turnover of 11 billion USD worldwide. However, rolling exploitation of GLP and GBHs in the last decades has led to environmental pollution, animal intoxication, bacterial resistance, and sustained occupational exposure of the herbicide of farm and companies' workers. Intoxication with these herbicides dysregulates the microbiome-gut-brain axis, cholinergic neurotransmission, and endocrine system, causing paralytic ileus, hyperkalemia, oliguria, pulmonary edema, and cardiogenic shock. Precision agriculture, i.e., an (information technology)-enhanced approach to crop management, including a site-specific determination of agrochemicals, derives from the benefits of smart materials (SMs), data science, and nanosensors. Those typically feature fluorescent molecularly imprinted polymers or immunochemical aptamer artificial receptors integrated with electrochemical transducers. Fabricated as portable or wearable lab-on-chips, smartphones, and soft robotics and connected with SM-based devices that provide machine learning algorithms and online databases, they integrate, process, analyze, and interpret massive amounts of spatiotemporal data in a user-friendly and decision-making manner. Exploited for the ultrasensitive determination of toxins, including GLP, they will become practical tools in farmlands and point-of-care testing. Expectedly, smart sensors can be used for personalized diagnostics, real-time water, food, soil, and air quality monitoring, site-specific herbicide management, and crop control.

Integration of Metallic Nanomaterials and Recognition Elements for the Specifically Monitoring of Pesticides in Electrochemical Sensing

Although all countries have been controlling the excessive use of pesticides, incidents of pesticide residues still existed. Electrochemical biosensors are extensively applied detection techniques to monitor pesticides with the help of different types of biorecognition components mainly including, antibodies, aptamers, enzymes (i.e., acetylcholinesterase, organophosphorus hydrolase, etc.), and synthetic molecularly imprinted polymers. Besides, the electrode materials mainly affected the sensitivity of electrochemical biosensors. Metallic nanomaterials with various structures and excellent electrical conductivity were desirable choice to construct electrochemical platforms to achieve the detection with high sensitivity and good specificity toward the target. This work reviewed the developed metallic materials including monometallic nanoparticles, bimetallic nanomaterials, metal atoms, metal oxides, metal molybdates, metal-organic frameworks, MXene, etc. Integration of recognition elements endowed the electrode materials with higher specificity toward the target pesticide. Besides, future challenges of metallic nanomaterials-based electrochemical biosensors for the detection of pesticides are also discussed and described.

A Review on Tetrabromobisphenol A: Human Biomonitoring, Toxicity, Detection and Treatment in the Environment

Tetrabromobisphenol A (TBBPA) is a known endocrine disruptor employed in a range of consumer products and has been predominantly found in different environments through industrial processes and in human samples. In this review, we aimed to summarize published scientific evidence on human biomonitoring, toxic effects and mode of action of TBBPA in humans. Interestingly, an overview of various pretreatment methods, emerging detection methods, and treatment methods was elucidated. Studies on exposure routes in humans, a combination of detection methods, adsorbent-based treatments and degradation of TBBPA are in the preliminary phase and have several limitations. Therefore, in-depth studies on these subjects should be considered to enhance the accurate body load of non-invasive matrix, external exposure levels, optimal design of combined detection techniques, and degrading technology of TBBPA. Overall, this review will improve the scientific comprehension of TBBPA in humans as well as the environment, and the breakthrough for treating waste products containing TBBPA.

In situ generated PANI promoted flexible photoelectrochemical biosensor for ochratoxin A based on GOx-stuffed DNA hydrogel as enhancer

A flexible photoelectrochemical (PEC) biosensor is proposed for the sensitive detection of ochratoxin A (OTA) based on glucose oxidase (GOx)-encapsulated target-responsive hydrogel, using Fenton reaction-mediated in situ formation of polyaniline (PANI) as signal amplified strategy. The target-responsive DNA hydrogels with high loading capacity can carry a large amount of GOx, which not only avoids laborious labeling process but also enhances the analytical performance. Upon introduction of target molecules, the hydrogel can be opened, and multiple GOx was released, thus producing lots of H₂O₂ via catalytic reduction of glucose. As a component of the Fenton reagent, H₂O₂ can react with the Fe²⁺ on the graphene oxidase-PAMAM-Fe²⁺ (GO-PAMAM-Fe²⁺) to generate Fe³⁺ and ·OH. This in turn can oxidize aniline and generate polyaniline (PANI), resulting in the enhancement of the photocurrent signal of GO-MoS₂-CdS photoelectrode. The GO-PAMAM-Fe²⁺ as the neighborhood component of GO-MoS₂-CdS-based photoactive material not only can increase the loading amount of Fe²⁺, but also can inhibit the decrease of photocurrent of GO-MoS₂-CdS by direct modification of Fe²⁺ on the photoactive material. Moreover, the high loading capacity of DNA hydrogel can efficiently promote the performance of the PEC biosensor. The PEC biosensor exhibited satisfactory analytical performance for OTA with a linear range of 0.0001-0.1 ng/mL and a low detection limit of 0.05 pg/mL. It presents recommendable specificity, stability, and practical applications. Importantly, the PEC biosensor provides a new concept for construction of PEC biosensing platform.

Wave-theory-based analysis of a fiber optic bio-sensor illuminated by radially polarized Bessel-Gauss beam: an approach for early diagnosis of breast cancer with a high-resolution wavelength-interrogation technique

With the establishment of validity using authoritative experimental results, an analytical investigation of an SPR-based fiber optic sensor, employing a wave-theory-based technique for determining breast cancer by shining a radially polarized Bessel-Gauss (RPBG) beam, is proposed. First, by using a radially polarized Gaussian (RPG) beam, the observed sensitivity is 9404.61 dB/RIU, where the acquired results are in good concurrence with the experimental data reported by Yan et al. [Chin. Opt. Lett.7, 909 (2009)COLHBT1671-7694]. Thus, the proposed theory has been validated with the reported experimental data. This theoretical analysis is further extended by utilizing an RPBG beam, where the observed sensitivity is 21,699.26 dB/RIU and 5846 nm/RIU, with a resolution of 4.61×10^-7, which is 2.5 times superior to the reported results to date. By using an RPBG beam, the proposed method, to our best knowledge, is the first to achieve much higher sensitivity in the area of fiber optic breast cancer detection. The higher sensitivity achieved at lower concentrations of an HER2 biomarker has led to the idea of early diagnosis of breast cancer by optically assessing it at its earlier stage using a high-resolution wavelength-interrogation technique.

Medical and Dental Applications of Titania Nanoparticles: An Overview

Currently, titanium oxide (TiO₂) nanoparticles are successfully employed in human food, drugs, cosmetics, advanced medicine, and dentistry because of their non-cytotoxic, non-allergic, and bio-compatible nature when used in direct close contact with the human body. These NPs are the most versatile oxides as a result of their acceptable chemical stability, lower cost, strong oxidation properties, high refractive index, and enhanced aesthetics. These NPs are fabricated by conventional (physical and chemical) methods and the latest biological methods (biological, green, and biological derivatives), with their advantages and disadvantages in this epoch. The significance of TiO₂ NPs as a medical material includes drug delivery release, cancer therapy, orthopedic implants, biosensors, instruments, and devices, whereas their significance as a dental biomaterial involves dentifrices, oral antibacterial disinfectants, whitening agents, and adhesives. In addition, TiO₂ NPs play an important role in orthodontics (wires and brackets), endodontics (sealers and obturating materials), maxillofacial surgeries (implants and bone plates), prosthodontics (veneers, crowns, bridges, and acrylic resin dentures), and restorative dentistry (GIC and composites).

Transgenerational effects of co-exposure to cadmium and carbofuran on zebrafish based on biochemical and transcriptomic analyses

The combined toxicity of heavy metals and pesticides to aquatic organisms is still largely unexplored. In this study, we investigated the combined impacts of cadmium (Cd) and carbofuran (CAR) on female zebrafish (F0 generation) and their following F1 generation. Results showed that mixtures of Cd and CAR induced acute synergistic effects on both zebrafish adults of the F0 generation and embryos of the F1 generation. Combined exposure to Cd and CAR could obviously alter the hepatic VTG level of females, and the individual exposures increased the relative mRNA levels of vtg1 and vtg2. Through maternal transmission, co-exposure of Cd and CAR caused toxicity to 4-day-old larvae of the F1 generation, evidenced by the significant changes in T4 and VTG levels, CYP450 activity, and the relative transcriptional levels of genes related to the hormone, oxidative stress, and apoptosis. These effects were also reflected by the global gene expression pattern to 7-day-old larvae of F1 generation using the transcriptomic analysis, and they could also affect energy metabolism. Our results provided a more comprehensive insight into the transgenerational toxic impacts of heavy metal and pesticide mixtures. These findings highlighted that it was highly necessary to consider transgenerational exposures in the ecological risk assessment of chemical mixtures.

Nanozyme-based sensors for detection of food biomarkers: a review

Nanozymes have piqued the curiosity of scientists in recent years because of their ability to demonstrate enzyme-like activity combined with advantages such as high stability, inexpensive availability, robust activity, and tunable properties. These attributes have allowed the successful application of nanozymes in sensing to detect various chemical and biological target analytes, overcoming the shortcomings of conventional detection techniques. In this review, we discuss recent developments of nanozyme-based sensors to detect biomarkers associated with food quality and safety. First, we present a brief introduction to this topic, followed by discussing the different types of sensors used in food biomarker detection. We then highlight recent studies on nanozyme-based sensors to detect food markers such as toxins, pathogens, antibiotics, growth hormones, metal ions, additives, small molecules, and drug residues. In the subsequent section, we discuss the challenges and possible solutions towards the development of nanozyme-based sensors for application in the food industry. Finally, we conclude the review by discussing future perspectives of this field towards successful detection and monitoring of food analytes.

Progress and challenges in sensing of mycotoxins using molecularly imprinted polymers

Mycotoxin is toxic secondary metabolite formed by certain filamentous fungi. This toxic compound can enter the food chain through contamination of food (e.g., by colonization of toxigenic fungi on food). In light of the growing concerns on the health hazards posed by mycotoxins, it is desirable to develop reliable analytical tools for their detection in food products in both sensitive and efficient manner. For this purpose, the potential utility of molecularly imprinted polymers (MIPs) has been explored due to their meritful properties (e.g., large number of tailor-made binding sites, sensitive template molecules, high recognition specificity, and structure predictability). This review addresses the recent advances in the application of MIPs toward the sensing of various mycotoxins (e.g., aflatoxins and patulin) along with their fabrication strategies. Then, performance evaluation is made for various types of MIP- and non-MIP-based sensing platforms built for the listed target mycotoxins in terms of quality assurance such as limit of detection (LOD). Further, the present challenges in the MIP-based sensing application of mycotoxins are discussed along with the future outlook in this research field.

Recent advances in nanomaterials-based optical and electrochemical aptasensors for detection of cyanotoxins

The existence of cyanotoxins poses serious threats to human health, it is highly desirable to develop specific and sensitive methods for rapid detection of cyanotoxins in food and water. Due to the distinct advantages of aptamer including high specificity, good stability and easy preparation, various aptamer-based sensors (aptasensors) have been proposed to promote the detection of cyanotoxins. In this review, we summarize recent advance in optical and electrochemical aptasensors for cyanotoxins sensing by integrating with versatile nanomaterials or innovative sensing strategies, such as colorimetric aptasensors, fluorescent aptasensors, surface enhancement Raman spectroscopy-based aptasensors, voltammetric aptasensors, electrochemical impedance spectroscopy-based aptasensors and photoelectrochemical aptasensors. We highlight the accomplishments and advancements of aptasensors with improved performance. Furthermore, the current challenges and future prospects in cyanotoxins detection are discussed from our perspectives, which we hope to provide more ideas for future researchers.

Recent advances in the potential applications of luminescence-based, SPR-based, and carbon-based biosensors

Abstract

The need for biosensors has evolved in the detection of molecules, diseases, and pollution from various sources. This requirement has headed to the development of accurate and powerful equipment for analysis using biological sensing component as a biosensor. Biosensors have the advantage of rapid detection that can beat the conventional methods for the detection of the same molecules. Bio-chemiluminescence-based sensors are very sensitive during use in biological immune assay systems. Optical biosensors are emerging with time as they have the advantage that they act with a change in the refractive index. Carbon nanotube-based sensors are another area that has an important role in the biosensor field. Bioluminescence gives much higher quantum yields than classical chemiluminescence. Electro-generated bioluminescence has the advantage of miniature size and can produce a high signal-to-noise ratio and the controlled emission. Recent advances in biological techniques and instrumentation involving fluorescence tag to nanomaterials have increased the sensitivity limit of biosensors. Integrated approaches provided a better perspective for developing specific and sensitive biosensors with high regenerative potentials. This paper mainly focuses on sensors that are important for the detection of multiple molecules related to clinical and environmental applications.

Key points

• The review focusses on the applications of luminescence-based, surface plasmon resonance-based, carbon nanotube-based, and graphene-based biosensors

• Potential clinical, environmental, agricultural, and food industry applications/uses of biosensors have been critically reviewed

• The current limitations in this field are discussed, as well as the prospects for future advancement

A REVIEW ON DETERMINATION OF THE VETERINARY DRUG RESIDUES IN FOOD PRODUCTS

In this paper, we discuss veterinary medicine and its applications in the food field as well as its risk to the health of humans and animals by the residues. We review how the veterinary residues enter and cause some detrimental effects. We also mention two techniques to determine the residue of veterinary medication that existed in food originating from animals, including classic and advanced techniques. Finally, we discuss the potential of various developed methods compared to some traditional techniques.

Ultra-Sensitive, Rapid and On-Site Sensing Harmful Ingredients Used in Aquaculture with Magnetic Fluid SERS

The integration of surface-enhanced Raman scattering (SERS) spectroscopy with magnetic fluid provides significant utility in point-of-care (POC) testing applications. Bifunctional magnetic-plasmonic composites have been widely employed as SERS substrates. In this study, a simple and cost-effective approach was developed to synthesize magnetic-plasmonic SERS substrates by decorating silver nanoparticles onto magnetic Fe₃O₄ nanoparticles (AgMNPs), which function both as SERS-active substrates and magnetic fluid particles. The strong magnetic responsivity from AgMNPs can isolate, concentrate, and detect target analytes from the irregular surface of fish skin rapidly. We fabricate a microfluid chip with three sample reservoirs that confine AgMNPs into ever smaller volumes under an applied magnetic field, which enhances the SERS signal and improves the detection limit by two orders of magnitude. The magnetic fluid POC sensor successfully detected malachite green from fish with excellent selectivity and high sensitivity down to the picomolar level. This work achieves a label-free, non-destructive optical sensing approach with promising potential for the detection of various harmful ingredients in food or the environment.

A visible light inducing photoelectrochemical biosensor with high-performance based on a porphyrin-sensitized carbon nitride composite

An outstanding photosensitive material plays a crucial role in building a high-performance and practical photoelectrochemical (PEC) biosensor.

High-Throughput Detection of Multiple Contaminants Based on Portable Photoelectrochromic Sensor Chip

With the increasing concerns about the environment and food safety, it is necessary to develop portable, low-cost, and high-throughput biosensors for the simultaneous detection of multiple contaminates. However, traditional photoelectrochemical (PEC) biosensors lack the ability of multiplexed assays due to the inherent mechanism limitation. Also, specialized instruments are necessary for most PEC biosensors. In this work, a portable high-throughput sensor chip has been successfully developed. By introducing electrochromic materials, the detection is based on color change instead of electric signals, which reduces the limitation of instruments. This designed sensor chip is composed of three parallel sensing channels fabricated by laser etching. Each channel is modified with TiO₂/3D-g-C₃N₄ composites with excellent PEC activity and electrochromic material Prussian blue (PB). Under light illumination, photoinduced electrons generated by TiO₂/3D-g-C₃N₄ are injected into PB, and blue PB is reduced to colorless Prussian white. Three organic contaminates, ochratoxin A, lincomycin, and edifenphos, can be simultaneously detected because the binding of these molecules with aptamers affects the electron transfer and the corresponding color changes. This portable and high-throughput sensor chip provides a convenient choice for multiplexed assays with good sensitivity and accuracy.

Recent advances in immunoassays and biosensors for mycotoxins detection in feedstuffs and foods

Mycotoxins are secondary metabolites produced by fungus. Many mycotoxin species are highly toxic and are frequently found in cereals and feedstuffs. So, powerful detection methods are vital and effective ways to prevent feed contamination. Traditional detection methods can no longer meet the needs of massive, real-time, simple, and fast mycotoxin monitoring. Rapid detection methods based on advanced material and sensor technology are the future trend. In this review, we highlight recent progress of mycotoxin rapid detection strategies in feedstuffs and foods, especially for simultaneous multiplex mycotoxin determination. Immunoassays, biosensors, and the prominent roles of nanomaterials are introduced. The principles of different types of recognition and signal transduction are explained, and the merits and pitfalls of these methods are compared. Furthermore, limitations and challenges of existing rapid sensing strategies and perspectives of future research are discussed.

Signal-off photoelectrochemical aptasensor for kanamycin: Strand displacement reaction combines p-n competition

A"signal-off" photoelectrochemical aptasensor based on p-n type semiconductor competitive quenching effect and strand displacement reaction was constructed for the determination of kanamycin. Au NPs@MgIn₂S₄-graphene composite was used as n-type photoactive semiconductor material. In the presence of the kanamycin, strand displacement reaction was triggered and the p-type CuInS₂ quantum dots labeled aptamer was introduced on the Au NPs@MgIn₂S₄-graphene surface. The CuInS₂ quantum dots can competitive consume the electron donors (AA) and light energy of the PEC system, thus quenched the anodic photocurrent of Au NPs@MgIn₂S₄-graphene. The photocurrent decreased with the increase of kanamycin concentration. The linear range of kanamycin was 1.0 pM-10 μM, and the detection limit was 1.7 pM. In addition, the method can be used for the determination of kanamycin in milk and honey.

Highly sensitive surface-plasmon-resonance- based fiber optic breast cancer detection by shining a Bessel-Gauss beam: a wave-theory-based approach

With experimental validation, an analytical exploration of a surface-plasmon-resonance- and evanescent-wave-based fiber optic biosensor, using Bessel-Gauss beams for early detection of breast cancer, is proposed and designed here. The observed sensitivity is 0.58 nm/ng/mL and 11,928.25 dB/RIU with a resolution of 8.38×10^-7, which is 10 times better than the reported ray-theory-based articles reported to date using a Gaussian beam. To analyze more effectively the higher-order modes and to achieve more similarity between the analytical and experimental solutions, the wave-theory-based approach is adopted here. With this approach, for the first time to our knowledge using a Bessel-Gauss beam, higher sensitivity is achieved for fiber optic breast cancer detection. The enhanced sensitivity at lower concentrations of the Human Epidermal Growth Factor Receptor 2 biomarker has conceptualized the idea of early detection of breast cancer by optically quantifying the earlier stage of cancer.

Nanobody-based immunosensing methods for safeguarding public health

Immunosensing methods are biosensing techniques based on specific recognition of an antigen-antibody immunocomplex, which have become commonly used in safeguarding public health. Taking advantage of antibody-related biotechnological advances, the utilization of an antigen-binding fragment of a heavy-chain-only antibody termed as 'nanobody' holds significant biomedical potential. Compared with the conventional full-length antibody, a single-domain nanobody retaining cognate antigen specificity possesses remarkable physicochemical stability and structural adaptability, which enables a flexible and efficient molecular design of the immunosensing strategy. This minireview aims to summarize the recent progress in immunosensing methods using nanobody targeting tumor markers, environmental pollutants, and foodborne microbes.

Liquid-Exfoliated 2D Materials for Optoelectronic Applications

Two-dimensional (2D) materials have attracted tremendous research attention in recent days due to their extraordinary and unique properties upon exfoliation from the bulk form, which are useful for many applications such as electronics, optoelectronics, catalysis, etc. Liquid exfoliation method of 2D materials offers a facile and low-cost route to produce large quantities of mono- and few-layer 2D nanosheets in a commercially viable way. Optoelectronic devices such as photodetectors fabricated from percolating networks of liquid-exfoliated 2D materials offer advantages compared to conventional devices, including low cost, less complicated process, and higher flexibility, making them more suitable for the next generation wearable devices. This review summarizes the recent progress on metal-semiconductor-metal (MSM) photodetectors fabricated from percolating network of 2D nanosheets obtained from liquid exfoliation methods. In addition, hybrids and mixtures with other photosensitive materials, such as quantum dots, nanowires, nanorods, etc. are also discussed. First, the various methods of liquid exfoliation of 2D materials, size selection methods, and photodetection mechanisms that are responsible for light detection in networks of 2D nanosheets are briefly reviewed. At the end, some potential strategies to further improve the performance the devices are proposed.

Rapid quantitative determination of fentanyl in human urine and serum using a gold-based immunochromatographic strip sensor

Fentanyl is a typical opioid that is used in surgical anesthesia. However, when abused, fentanyl can lead to addiction and even death. To better control the use of fentanyl, it is necessary to develop rapid and sensitive detection methods. In this study, an ultrasensitive monoclonal antibody (mAb) was prepared and used to develop an indirect competitive enzyme-linked immunosorbent assay (ic-ELISA) and a colloidal gold-based immunochromatographic strip (CG-ICS) for the analysis of fentanyl in urine and serum. Under optimum conditions, the anti-fentanyl mAb belonging to the subtype of IgG2b showed a half-maximal inhibitory concentration (IC50) of 0.11 ng mL-1 and a linear range of detection of 0.020-0.50 ng mL-1. Fenanyl-spiked original urine and serum diluted eight times were used for the analysis of fentanyl by ic-ELISA and CG-ICS. IC50 from the standard curves was 0.46 ng mL-1 for urine and 2.6 ng mL-1 for serum in ic-ELISA and 1.6 ng mL-1 for urine and 6.27 ng mL-1 for serum in CG-ICS. The recovery test revealed that the ic-ELISA and CG-ICS, with a recovery rate of 87.0-108.4% and a coefficient of variation of 3.3-10.9%, were the same reliable tools as the liquid chromatography tandem mass spectrometry for fentanyl analysis in real samples.

A signal-on photoelectrochemical aptasensor for chloramphenicol assay based on 3D self-supporting AgI/Ag/BiOI Z-scheme heterojunction arrays

Severe challenges are still remained for development of highly sensitive, selective and stable photoelectrochemical (PEC) sensing technology, albeit with its broad application for chloramphenicol (CAP) detection. Herein, a novel "signal-on" PEC aptasensor was fabricated based on a 3D self-supporting Z-scheme AgI/Ag/BiOI heterojunction arrays subtly integrated with in-situ formed biocatalytic precipitation (BCP) for highly sensitive and selective determination of CAP. Impressively, the HRP modified CAP aptamer (HRP-CAP aptamer) was released from the electrode by its strong affinity to the introduced CAP, and gradually terminated the BCP reaction, in turn recovering the photocurrent. By virtues of the 3D self-supporting AgI/Ag/BiOI Z-scheme heterojunction arrays and BCP signal amplification strategy, the resultant PEC sensor exhibited a wide linear range of 2-250 nM with a limit of detection (LOD) as low as 0.226 nM (S/N = 3). This work opens a new avenue for design of PEC aptasensing strategy and exhibits the marvelous potential in bioanalysis of environmental samples.

Veterinary Drug Residues in Animal-Derived Foods: Sample Preparation and Analytical Methods

Veterinary drugs are used to treat livestock and aquatic diseases and thus are introduced into animal-derived foods, endangering consumer health and safety. Antibiotic resistance is rapidly becoming a major worldwide problem, and there has been a steady increase in the number of pathogens that show multi-drug resistance. Illegal and excessive use of veterinary drugs in animals and aquaculture has serious adverse effects on humans and on all other environmental organisms. It is necessary to develop simple extraction methods and fast analytical methods to effectively detect veterinary drug residues in animal-derived foods. This review summarizes the application of various sample extraction techniques and detection and quantification methods for veterinary drug residues reported in the last decade (2010-2020). This review compares the advantages and disadvantages of various extraction techniques and detection methods and describes advanced methods, such as those that use electrochemical biosensors, piezoelectric biosensors, optical biosensors, and molecularly imprinted polymer biosensors. Finally, the future prospects and trends related to extraction methods, detection methods and advanced methods for the analysis of veterinary drug residues in animal-derived foods are summarized.

K, Rayadurgam J, Rajasekhara Reddy S. Naturally derived sugar-based ionic liquids: an emerging tool for sustainable organic synthesis and chiral recognition

In the past decade, the synthesis of sugar-based ionic liquids (SILs) from natural sugars has been described as a promising strategy.

Electron Acceptors Co-Regulated Self-Powered Photoelectrochemical Strategy and Its Application for Circulating Tumor Nucleic Acid Detection Coupled with Recombinase Polymerase Amplification

Biosensor working in a self-powered mode has been widely concerned because it produces a signal when the bias potential is 0 V. However, the self-powered mode is used only when the materials have self-powered properties. Conversion of non-self-powered to self-powered through molecular regulation can solve this problem effectively. Here, we fabricated a self-powered photoelectrochemical mode based on co-regulation of electron acceptors methylene blue (MB) and p-nitrophenol (p-NP). AuNPs@ZnSe nanosheet-modified gold electrode (AuNPs@ZnSeNSs/GE) gave a small photocurrent at 0 V. In the presence of MB and p-NP, AuNPs@ZnSeNSs/GE gave the strongest photocurrent at 0 V. Accordingly, an electron acceptor co-regulated self-powered photoelectrochemical assay was fabricated. As proof-of-concept demonstrations, this assay was applied for prostate cancer circulating tumor nucleic acid biomarker, KLK2 and PCA3, detection combined with in situ recombinase polymerase amplification strategy. This assay generated a strong photocurrent and was sensitive to the variation of KLK2 and PCA3 concentration. The limits of detection were 30 and 32 aM, respectively. We anticipate this electron acceptor co-regulated self-powered photoelectrochemical mode to pave a new way for the development of self-powered sensing.

Recent advances in nanocomposite-based electrochemical aptasensors for the detection of toxins

Toxins are one of the major threatening factors to human and animal health, as well as economic growth. There is therefore an urgent demand from various communities to develop novel analytical methods for the sensitive detection of toxins in complex matrixes. Among the as-developed toxin detection strategies, nanocomposite-based aptamer sensors (termed as aptasensors) show tremendous potential for combating toxin pollution; in particular electrochemical (EC) aptasensors have received significant attention because of their unique advantages, including simplicity, rapidness, high sensitivity, low cost and suitability for field-testing. This paper reviewed the recently published approaches for the development of nanocomposite-/nanomaterial-based EC aptasensors for the detection of toxins with high assaying performance, and their potential applications in environmental monitoring, clinical diagnostics, and food safety control by summarizing the detection of different types of toxins, including fungal mycotoxins, algal toxins and bacterial enterotoxins. The effects of nanocomposite properties on the detection performance of EC aptasensors have been fully addressed for supplying readers with a comprehensive understanding of their improvement. The current technical challenges and future prospects of this subject have also been discussed.

Biomedical Applications of TiO2 Nanostructures: Recent Advances

Titanium dioxide (TiO2) nanostructures are one of the most plentiful compounds that have emerged in various fields of technology such as medicine, energy and biosensing. Various TiO2 nanostructures (nanotubes [NTs] and nanowires) have been employed in photoelectrochemical (PEC) biosensing applications, greatly enhancing the detection of targets. TiO2 nanostructures, used as reinforced material or coatings for the bare surface of titanium implants, are excellent additive materials to compensate titanium implants deficiencies-like poor surface interaction with surrounding tissues-by providing nanoporous surfaces and hierarchical structures. These nanostructures can also be loaded by diversified drugs-like osteoporosis drugs, anticancer and antibiotics-and used as local drug delivery systems. Furthermore, TiO2 nanostructures and their derivatives are new emerging antimicrobial agents to overcome human pathogenic microorganisms. However, like all other nanomaterials, toxicity and biocompatibility of TiO2 nanostructures must be considered. This review highlights recent advances, along with the properties and numerous applications of TiO2-based nanostructure compounds in nano biosensing, medical implants, drug delivery and antibacterial fields. Moreover, in the present study, some recent advances accomplished on the pharmaceutical applications of TiO2 nanostructures, as well as its toxicity and biocompatibility, are presented.

ZnO-reduced graphene oxide composite based photoelectrochemical aptasensor for sensitive Cd(II) detection with methylene blue as sensitizer

In this paper a photoelectrochemical (PEC) aptasensor based on specific recognition with conformational changed after the target Cd(II) identification was fabricated. A ZnO and reduced graphene oxide (ZnO-rGO) nanocomposite with enhanced PEC activity was designed as photoactive material. After the further incorporation of gold nanoparticles (AuNPs) with ZnO-rGO nanocomposite, the enhanced photocurrent signal could be detected owing to the localized surface plasmon resonance and good conductivity of AuNPs. In addition, AuNPs were used as anchors for immobilization of -SH modified aptamer S1. After that aptamer S2 was paired with S1 sequence to form complementary double stranded DNA (dsDNA) on the electrode surface. Methylene blue (MB) was acted as sensitizer and assembled in dsDNA structure to amplify photocurrent response. When Cd(II) was bound to the aptamer presented on the sensing interface, S2 specifically recognized and captured Cd(II), which resulted in the unwinding of dsDNA structure and the separation of MB molecules from the electrode surface with photocurrent response decreased. The photocurrent was detected by a double-working-electrode system, which used the modified electrode as the first working electrode and glassy carbon electrode (GCE) as the second working electrode. Dopamine (DA) was added to the electrolyte and acted as the electron donor, which could be oxidized on the modified electrode and reduced on the GCE to form a cyclic reaction, leading to the enhanced photocurrent response with improved photocurrent stability. This MB sensitized PEC aptasensor exhibited a high sensitivity with a detection limit of 1.8 × 10^-12 mol/L (3σ). Thus, a highly sensitive aptasensor with double-working-electrode detection method for Cd(II) determination were established and further applied to the water samples analysis.

Applications of Graphene Quantum Dots in Biomedical Sensors

Due to the proliferative cancer rates, cardiovascular diseases, neurodegenerative disorders, autoimmune diseases and a plethora of infections across the globe, it is essential to introduce strategies that can rapidly and specifically detect the ultralow concentrations of relevant biomarkers, pathogens, toxins and pharmaceuticals in biological matrices. Considering these pathophysiologies, various research works have become necessary to fabricate biosensors for their early diagnosis and treatment, using nanomaterials like quantum dots (QDs). These nanomaterials effectively ameliorate the sensor performance with respect to their reproducibility, selectivity as well as sensitivity. In particular, graphene quantum dots (GQDs), which are ideally graphene fragments of nanometer size, constitute discrete features such as acting as attractive fluorophores and excellent electro-catalysts owing to their photo-stability, water-solubility, biocompatibility, non-toxicity and lucrativeness that make them favorable candidates for a wide range of novel biomedical applications. Herein, we reviewed about 300 biomedical studies reported over the last five years which entail the state of art as well as some pioneering ideas with respect to the prominent role of GQDs, especially in the development of optical, electrochemical and photoelectrochemical biosensors. Additionally, we outline the ideal properties of GQDs, their eclectic methods of synthesis, and the general principle behind several biosensing techniques.