Nanomaterials-based biosensors for detection of microorganisms and microbial toxins

Antitoxin nanoparticles: design considerations, functional mechanisms, and applications in toxin neutralization

The application of nanotechnology has significantly advanced the development of novel platforms that enhance disease treatment and diagnosis. A key innovation in this field is the creation of antitoxin nanoparticles (ATNs), designed to address toxin exposure. These precision-engineered nanosystems have unique physicochemical properties and selective binding capabilities, allowing them to effectively capture and neutralize toxins from various biological, chemical, and environmental sources. In this review, we thoroughly examine their therapeutic and diagnostic potential for managing toxin-related challenges. We also explore recent advancements and offer critical insights into the design and clinical implementation of ATNs.

A Rapid Total Bacterial Count Method for Food Samples using Syringe Filters and Lectin-Conjugated Semiconductor Nanorods

Total bacterial count in food is one of important food safety criteria. The current plate count method (Heterotrophic Plate Count) for food analysis requires microbiology lab facilities and at least 2 days turnover time. We developed a rapid fluorescence-based total bacterial count method that utilises semiconductor nanorods (SNRs) conjugated with a lectin Griffonia simplicifolia II (GSII-SNRs) to stain bacterial cells captured on syringe filters, via the common N-acetylglucosamine molecules on bacterial cell wall. This "Filter-and-Stain" detection method has a rapid turnover time of 20 min. The fluorescence emission can be seen under UV light with minimum interference from food sample background. The fluorescence intensity quantified through image analysis is proportional to the bacterial concentration with a limit of detection of 1000 CFU/mL, for total bacterial count assessment in food safety. Moreover, the GSII-SNRs do not bind to heat inactivated bacterial cells, and thus can differentiate live and dead bacteria. Our method has been validated with representative food (coffee powder, raw spinach leaves, and ready-to-eat tomato salsa) to demonstrate its high potential for on-site food safety assessment, especially in places with no immediate access to microbiology labs.

A rapid total bacterial count method using gold nanoparticles conjugated with an aptamer for water quality assessment

Total bacterial count is a routine parameter in microbial safety assessment used in many fields, such as drinking water and industrial water testing. The current gold standard method for counting bacteria is the plate culture method (or heterotrophic plate count) that requires a microbiology laboratory and a long turnover time of at least 24 hours. To tackle these shortcomings, we developed a rapid total bacterial count method that relies on gold nanoparticles (AuNPs) conjugated with affinity ligands to stain bacterial cells captured on a syringe filter. Two affinity ligands were exploited, i.e. a DNA aptamer (AB2) and a lectin Griffonia simplicifolia II (GSII) that recognize bacterial cell wall commonalities, i.e. peptidoglycan and its amino sugars. Upon proper formulation with addition of a surfactant, the AB2 conjugated AuNPs (AB2-AuNPs) can selectively stain bacterial cells captured on the filter membrane with a higher sensitivity than GSII-AuNPs. Measuring the staining intensity using an in-house-built handheld detector allowed us to correlate its intensity reading with the total number of bacterial units present. This bacteria quantification method, referred to as "Filter-and-Stain", had an efficient turnover time of 20 min suggesting its potential usage for rapid on-site applications. Additionally, the detection sensitivity provided by the AB2-AuNP nanoreagent offered a limit of detection as low as 100 CFU mL-1. We have demonstrated the use of the AB2-AuNPs for detection of bacteria from environmental water samples.

Nanoparticles-induced potential toxicity on human health: Applications, toxicity mechanisms, and evaluation models

Nanoparticles (NPs) have become one of the most popular objects of scientific study during the past decades. However, despite wealth of study reports, still there is a gap, particularly in health toxicology studies, underlying mechanisms, and related evaluation models to deeply understanding the NPs risk effects. In this review, we first present a comprehensive landscape of the applications of NPs on health, especially addressing the role of NPs in medical diagnosis, therapy. Then, the toxicity of NPs on health systems is introduced. We describe in detail the effects of NPs on various systems, including respiratory, nervous, endocrine, immune, and reproductive systems, and the carcinogenicity of NPs. Furthermore, we unravels the underlying mechanisms of NPs including ROS accumulation, mitochondrial damage, inflammatory reaction, apoptosis, DNA damage, cell cycle, and epigenetic regulation. In addition, the classical study models such as cell lines and mice and the emerging models such as 3D organoids used for evaluating the toxicity or scientific study are both introduced. Overall, this review presents a critical summary and evaluation of the state of understanding of NPs, giving readers more better understanding of the NPs toxicology to remedy key gaps in knowledge and techniques.

Effect of Risk-Focused Diversified Safety Management Mode in Patients with Major Artery Stent Implantation

Background

Intracranial atherosclerotic stenosis (ICAS) causes a series of neurological symptoms, such as vertigo, impaired consciousness, limb weakness, ataxia, dysphagia, ocular motility disorders, and visual impairment. With the improvement of people's living standards, there are higher requirements for nursing care. Nursing, as an indispensable part of medical care, is closely related to achieving the goal of patient's safety and the overall quality of nurses, quality of care, and nursing management methods.

Objective

To explore the effect of risk-centered diversified safety management in patients undergoing aortic stenting.

Methods

Eighty patients with cerebral infarction were selected and treated with percutaneous transluminal angioplasty and stent implantation (PTAS). Then they were divided into a control group (40 cases) with routine monitoring and an experimental group (40 cases) with risk-focused intervention of a diversified safety management model according to the mode of care. Patient satisfaction and blood index test results were compared after the intervention.

Results

Patients in the experimental group had 6 falls, 3 bed falls, 3 phlebitis, 4 tube slips, and 10 deep vein thrombosis, all significantly fewer than those in the control group. Thirty-eight patients in the experimental group expressed satisfaction with safe management, which was substantially better than the control group (P < 0.05). The levels of tissue plasminogen activator (tPA), plasminogen activator inhibitor-1 (PA1-1), and von Willebrand factor (vWF) in the experimental group were (13.5 ± 1.3) ng/mL, (60.1 ± 9.9) ng/mL, and (2.1 ± 0.2), respectively, which were substantially lower than those in the control group ((14.6 ± 2.4) ng/mL, (64.2 ± 10.7) ng/mL, and (2.8 ± 0.3)), respectively (P < 0.05).

Conclusion

The risk-centered diversified safety management model can effectively reduce the probability of adverse events in patients, improve patient satisfaction with nursing services, and promote faster postoperative recovery, which has clinical application value.

Emerging bioanalytical sensors for rapid and close-to-real-time detection of priority abiotic and biotic stressors in aquaculture and culture-based fisheries

Abiotic stresses of various chemical contamination of physical, inorganic, organic and biotoxin origin and biotic stresses of bacterial, viral, parasitic and fungal origins are the significant constraints in achieving higher aquaculture production. Testing and rapid detection of these chemical and microbial contaminants are crucial in identifying and mitigating abiotic and biotic stresses, which has become one of the most challenging aspects in aquaculture and culture-based fisheries. The classical analytical techniques, including titrimetric methods, spectrophotometric, mass spectrometric, spectroscopic, and chromatographic techniques, are tedious and sometimes inaccessible when required. The development of novel and improved bioanalytical methods for rapid, selective and sensitive detection is a wide and dynamic field of research. Biosensors offer precise detection of biotic and abiotic stressors in aquaculture and culture-based fisheries within no time. This review article allows filling the knowledge gap for detection and monitoring of chemical and microbial contaminants of abiotic and biotic origin in aquaculture and culture-based fisheries using nano(bio-) analytical technologies, including nano(bio-)molecular and nano(bio-)sensing techniques.

A colorimetric aptasensor based on gold nanoparticles for detection of microbial toxins: an alternative approach to conventional methods

Frequent contamination of foods with microbial toxins produced by microorganisms such as bacteria, fungi, and algae represents an increasing public health problem that requires the development of quick and easy tools to detect them at trace levels. Recently, it has been found that colorimetric detection methods may replace traditional methods in the field because of their ease of use, quick response, ease of manufacture, low cost, and naked-eye visibility. Therefore, it is suitable for fieldwork, especially for work in remote areas of the world. However, the development of colorimetric detection methods with low detection limits is a challenge that limits their wide applicability in the detection of food contaminants. To address these challenges, nanomaterial-based transduction systems are used to construct colorimetric biosensors. For example, gold nanoparticles (AuNPs) provide an excellent platform for the development of colorimetric biosensors because they offer the advantages of easy synthesis, biocompatibility, advanced surface functionality, and adjustable physicochemical properties. The selectivity of the colorimetric biosensor can be achieved by the combination of aptamers and gold nanoparticles, which provides an unprecedented opportunity to detect microbial toxins. Compared to antibodies, aptamers have significant advantages in the analysis of microbial toxins due to their smaller size, higher binding affinity, reproducible chemical synthesis and modification, stability, and specificity. Two colorimetric mechanisms for the detection of microbial toxins based on AuNPs have been described. First, sensors that use the localized surface plasmon resonance (LSPR) phenomenon of gold nanoparticles can exhibit very strong colors in the visible range because of changes caused by aggregation or disaggregation. Second, the detection mechanism of AuNPs is based on their enzyme mimetic properties and it is possible to construct a colorimetric biosensor based on the 3,3',5,5'-tetramethylbenzidine/Hydrogen peroxide, TMB/H₂O₂ reaction to detect microbial toxins. Therefore, this review summarizes the recent applications of AuNP-based colorimetric aptasensors for detecting microbial toxins, including bacterial toxins, fungal toxins, and algal toxins focusing on selectivity, sensitivity, and practicality. Finally, the most important current challenges in this field and future research opportunities are discussed.

Transcription Factor-Based Biosensors for Detecting Pathogens

Microorganisms are omnipresent and inseparable from our life. Many of them are beneficial to humans, while some are not. Importantly, foods and beverages are susceptible to microbial contamination, with their toxins causing illnesses and even death in some cases. Therefore, monitoring and detecting harmful microorganisms are critical to ensuring human health and safety. For several decades, many methods have been developed to detect and monitor microorganisms and their toxicants. Conventionally, nucleic acid analysis and antibody-based analysis were used to detect pathogens. Additionally, diverse chromatographic methods were employed to detect toxins based on their chemical and structural properties. However, conventional techniques have several disadvantages concerning analysis time, sensitivity, and expense. With the advances in biotechnology, new approaches to detect pathogens and toxins have been reported to compensate for the disadvantages of conventional analysis from different research fields, including electrochemistry, nanotechnology, and molecular biology. Among them, we focused on the recent studies of transcription factor (TF)-based biosensors to detect microorganisms and discuss their perspectives and applications. Additionally, the other biosensors for detecting microorganisms reported in recent studies were also introduced in this review.

Fluorescent-based nanosensors for selective detection of a wide range of biological macromolecules: A comprehensive review

Thanks to their unique attributes, such as good sensitivity, selectivity, high surface-to-volume ratio, and versatile optical and electronic properties, fluorescent-based bioprobes have been used to create highly sensitive nanobiosensors to detect various biological and chemical agents. These sensors are superior to other analytical instrumentation techniques like gas chromatography, high-performance liquid chromatography, and capillary electrophoresis for being biodegradable, eco-friendly, and more economical, operational, and cost-effective. Moreover, several reports have also highlighted their application in the early detection of biomarkers associated with drug-induced organ damage such as liver, kidney, or lungs. In the present work, we comprehensively overviewed the electrochemical sensors that employ nanomaterials (nanoparticles/colloids or quantum dots, carbon dots, or nanoscaled metal-organic frameworks, etc.) to detect a variety of biological macromolecules based on fluorescent emission spectra. In addition, the most important mechanisms and methods to sense amino acids, protein, peptides, enzymes, carbohydrates, neurotransmitters, nucleic acids, vitamins, ions, metals, and electrolytes, blood gases, drugs (i.e., anti-inflammatory agents and antibiotics), toxins, alkaloids, antioxidants, cancer biomarkers, urinary metabolites (i.e., urea, uric acid, and creatinine), and pathogenic microorganisms were outlined and compared in terms of their selectivity and sensitivity. Altogether, the small dimensions and capability of these nanosensors for sensitive, label-free, real-time sensing of chemical, biological, and pharmaceutical agents could be used in array-based screening and in-vitro or in-vivo diagnostics. Although fluorescent nanoprobes are widely applied in determining biological macromolecules, unfortunately, they present many challenges and limitations. Efforts must be made to minimize such limitations in utilizing such nanobiosensors with an emphasis on their commercial developments. We believe that the current review can foster the wider incorporation of nanomedicine and will be of particular interest to researchers working on fluorescence technology, material chemistry, coordination polymers, and related research areas.

Biosensors for Fungal Detection

Due to the serious threat of invasive fungal infections, there is an emergent need for improved a sensitive and more accurate diagnostic tests for detection of systemic pathogenic fungi and plant health. Traditional fungal diagnosis can only be achieved at later growing phases. The complex and difficult immunodiagnostic is also widely employed. Enzyme-based immunoassays which lead to cross-interaction with different fungi still also obeyed. A polymerase chain reactions (PCRs)- based molecular diagnosis are does not enable precise identification of fungal pathogens, or the ability to test isolates for drug sensitivity. In the future, biosensing technologies and nanotechnological tools, will improve diagnosis of pathogenic fungi through a specific and sensitive pathogen detection. This report systematically reviews the most prominent biosensor trends for fungi detection.

Recent progress in mycotoxins detection based on surface-enhanced Raman spectroscopy

Mycotoxins are toxic compounds naturally produced by certain types of fungi. The contamination of mycotoxins can occur on numerous foodstuffs, including cereals, nuts, fruits, and spices, and pose a major threat to humans and animals by causing acute and chronic toxic effects. In this regard, reliable techniques for accurate and sensitive detection of mycotoxins in agricultural products and food samples are urgently needed. As an advanced analytical tool, surface-enhanced Raman spectroscopy (SERS), presents several major advantages, such as ultrahigh sensitivity, rapid detection, fingerprint-type information, and miniaturized equipment. Benefiting from these merits, rapid growth has been observed under the topic of SERS-based mycotoxin detection. This review provides a comprehensive overview of the recent achievements in this area. The progress of SERS-based label-free detection, aptasensor, and immunosensor, as well as SERS combined with other techniques, has been summarized, and in-depth discussion of the remaining challenges has been provided, in order to inspire future development of translating the techniques invented in scientific laboratories into easy-to-operate analytic platforms for rapid detection of mycotoxins.

Advances in nanomaterial-based electrochemical biosensors for the detection of microbial toxins, pathogenic bacteria in food matrices

There is a growing demand to protect food products against the hazard of microbes and their toxins. To satisfy such goals, it is important to develop highly sensitive, reliable, sophisticated, rapid, and cost-effective sensing techniques such as electrochemical sensors/biosensors. Although diverse forms of nanomaterials (NMs)-based electrochemical sensing methods have been introduced in markets, the reliability of commercial products is yet insufficient to meet the practical goal. In this review, we focused on: 1) sources of pathogenic microbes and their toxins; 2) possible routes of their entrainment in food, and 3) current development of NM-based biosensors to realize real-time detection of the target analytes. At last, future prospects and challenges in this research field are discussed.

Johnson E, Littlechild J, Winlove CP, Vollmer F, Gow NAR. Biosensors and Diagnostics for Fungal Detection

Early detection is critical to the successful treatment of life-threatening infections caused by fungal pathogens, as late diagnosis of systemic infection almost always equates with a poor prognosis. The field of fungal diagnostics has some tests that are relatively simple, rapid to perform and are potentially suitable at the point of care. However, there are also more complex high-technology methodologies that offer new opportunities regarding the scale and precision of fungal diagnosis, but may be more limited in their portability and affordability. Future developments in this field are increasingly incorporating new technologies provided by the use of new format biosensors. This overview provides a critical review of current fungal diagnostics and the development of new biophysical technologies that are being applied for selective new sensitive fungal biosensors to augment traditional diagnostic methodologies.

Toward a nanopaper-based and solid phase immunoassay using FRET for the rapid detection of bacteria

In this study, we propose a novel sensitive solid-based immunosensor developed on a plasmonic nanopaper platform for the detection of Escherichia coli (E. coli) bacteria. This plasmonic nanopaper that comprises of carboxylated bacterial cellulose (CBC) impregnated with gold nanoparticles (AuNP-CBC), employed as a quencher and a sustainable functionalized platform to be conjugated with protein A. Thus, the conjugated protein A allows the aligned linkage of EAb-QD (anti-E. coli conjugated quantum dot) and EAb-AF (anti-E. coli conjugated Alexa Fluor 488). Interestingly, once E. coli was captured by the AuNP-CBC/EAb-QD or AuNP-CBC/EAb-AF, the energy transfer from the QD or Alexa Fluor fluorophores is triggered due to the conformational change in the antibody structure and this, in turn, causes a decrease in the distance between fluorophores and the quencher nanopaper and, therefore diminishing their photoluminescence. The immunosensors performed successfully to recognize E. coli at concentrations as low as 50 CFU mL⁻¹ in the standard buffer. The examined functionality of the immunosensors in a real matrix such as chicken extract and lettuce juice demonstrated a highly efficient response while QD is the main fluorophore with a limit of detection around 100 CFU mL⁻¹.

An Overview of the Applications of Nanomaterials and Nanodevices in the Food Industry

The efficient progress in nanotechnology has transformed many aspects of food science and the food industry with enhanced investment and market share. Recent advances in nanomaterials and nanodevices such as nanosensors, nano-emulsions, nanopesticides or nanocapsules are intended to bring about innovative applications in the food industry. In this review, the current applications of nanotechnology for packaging, processing, and the enhancement of the nutritional value and shelf life of foods are targeted. In addition, the functionality and applicability of food-related nanotechnologies are also highlighted and critically discussed in order to provide an insight into the development and evaluation of the safety of nanotechnology in the food industry.

Selective Lanthanide Sensing with Gold Nanoparticles and Hydroxypyridinone Chelators

The octadentate hydroxypyridinone chelator 3,4,3-LI(1,2-HOPO) is a promising therapeutic agent because of its high affinity for f-block elements and noncytotoxicity at medical dosages. The interaction between 3,4,3-LI(1,2-HOPO) and other biomedically relevant metals such as gold, however, has not been explored. Gold nanoparticles functionalized with chelators have demonstrated great potential in theranostics, yet thus far, no protocol that combines 3,4,3-LI(1,2-HOPO) and colloidal gold has been developed. Here, we characterize the solution thermodynamic properties of the complexes formed between 3,4,3-LI(1,2-HOPO) and Au³⁺ ions and demonstrate how under specific pH conditions the chelator promotes the growth of gold nanoparticles, acting as both reducing and stabilizing agent. 3,4,3-LI(1,2-HOPO) ligands on the nanoparticle surface remain active and selective toward f-block elements, as evidenced by gold nanoparticle selective aggregation. Finally, a new colorimetric assay capable of reaching the detection levels necessary for the quantification of lanthanides in waste from industrial processes is developed based on the inhibition of particle growth by lanthanides.

Sensors, Biosensors, and Analytical Technologies for Aquaculture Water Quality

In aquaculture industry, fish, shellfish, and aquatic plants are cultivated in fresh, salt, or brackish waters. The increasing demand of aquatic products has stimulated the rapid growth of aquaculture industries. How to effectively monitor and control water quality is one of the key concerns for aquaculture industry to ensure high productivity and high quality. There are four major categories of water quality concerns that affect aquaculture cultivations, namely, (1) physical parameters, e.g., pH, temperature, dissolved oxygen, and salinity, (2) organic contaminants, (3) biochemical hazards, e.g., cyanotoxins, and (4) biological contaminants, i.e., pathogens. While the physical parameters are affected by climate changes, the latter three are considered as environmental factors. In this review, we provide a comprehensive summary of sensors, biosensors, and analytical technologies available for monitoring aquaculture water quality. They include low-cost commercial sensors and sensor network setups for physical parameters. They also include chromatography, mass spectrometry, biochemistry, and molecular methods (e.g., immunoassays and polymerase chain reaction assays), culture-based method, and biophysical technologies (e.g., biosensors and nanosensors) for environmental contamination factors. According to the different levels of sophistication of various analytical techniques and the information they can provide (either fine fingerprint, highly accurate quantification, semiquantification, qualitative detection, or fast screening), we will comment on how they may be used as complementary tools, as well as their potential and gaps toward current demand of real-time, online, and/or onsite detection.

Sensing of circulating cancer biomarkers with metal nanoparticles

The analysis of circulating cancer biomarkers, including cell-free and circulating tumor DNA, circulating tumor cells, microRNA and exosomes, holds promise in revolutionizing cancer diagnosis and prognosis using body fluid analysis, also known as liquid biopsy. To enable clinical application of these biomarkers, new analytical tools capable of detecting them in very low concentrations in complex sample matrixes are needed. Metal nanoparticles have emerged as extraordinary analytical scaffolds because of their unique optoelectronic properties and ease of functionalization. Hence, multiple analytical techniques have been developed based on these nanoparticles and their plasmonic properties. The aim of this review is to summarize and discuss the present development on the use of metal nanoparticles for the analysis of circulating cancer biomarkers. We examine how metal nanoparticles can be used as (1) analytical transducers in various sensing principles, such as aggregation induced colorimetric assays, plasmon resonance energy transfer, surface enhanced Raman spectroscopy, and refractive index sensing, and (2) signal amplification elements in surface plasmon resonance spectroscopy and electrochemical detection. We critically discuss the clinical relevance of each category of circulating biomarkers, followed by a thorough analysis of how these nanoparticle-based designs have overcome some of the main challenges that gold standard analytical techniques currently face, and what new directions the field may take in the future.

High-throughput identification and diagnostics of pathogens and pests: Overview and practical recommendations

High-throughput identification technologies provide efficient tools for understanding the ecology and functioning of microorganisms. Yet, these methods have been only rarely used for monitoring and testing ecological hypotheses in plant pathogens and pests in spite of their immense importance in agriculture, forestry and plant community dynamics. The main objectives of this manuscript are the following: (a) to provide a comprehensive overview about the state-of-the-art high-throughput quantification and molecular identification methods used to address population dynamics, community ecology and host associations of microorganisms, with a specific focus on antagonists such as pathogens, viruses and pests; (b) to compile available information and provide recommendations about specific protocols and workable primers for bacteria, fungi, oomycetes and insect pests; and (c) to provide examples of novel methods used in other microbiological disciplines that are of great potential use for testing specific biological hypotheses related to pathology. Finally, we evaluate the overall perspectives of the state-of-the-art and still evolving methods for diagnostics and population- and community-level ecological research of pathogens and pests.

Phage-based assay for rapid detection of bacterial pathogens in blood by Raman spectroscopy

Sepsis is a systemic inflammatory response ensuing from presence and persistence of microorganisms in the bloodstream. The possibility to identify them at low concentrations may improve the problem of human health and therapeutic outcomes. So, sensitive and rapid diagnostic systems are essential to evaluate bacterial infections during the time, also reducing the cost. In this study, from random M13 phage display libraries, we selected phage clones that specifically bind surface of Staphyloccocus aureus, Pseudomonas aeruginosa and Escherichia coli. Then, commercial magnetic beads were functionalized with phage clones through covalent bond and used as capture and concentrating of pathogens from blood. We found that phage-magnetic beads complex represents a network which enables a cheap, high sensitive and specific detection of the bacteria involved in sepsis by micro-Raman spectroscopy. The enter process required 6 h and has the limit of detection of 10 Colony Forming Units on 7 ml of blood (CFU/7 ml).

Nanoparticle Enhanced Antibody and DNA Biosensors for Sensitive Detection of Salmonella

Bacteria-related pathogenic diseases are one of the major health problems throughout the world. Salmonella is a genus of rod-shaped Gram-negative enterobacteria of which more than 2600 serotypes have been identified. Infection with Salmonella can cause salmonellosis, a serious bacterial toxi-infection syndrome associated with gastroenteritis, and paralyphoid and typhoid fevers. Its rapid and sensitive detection is a key to the prevention of problems related to health. This paper describes the development of antibody and DNA sensors for Salmonella detection using a microfluidic-based electrochemical system. Commercial Salmonella typhimurium and Salmonella typhimurium from human stool samples were investigated using standard and nanomaterial-amplified antibody sensors. S. typhimurium could be detected down to 1 cfu mL^-1. The specificity of immunoassay was tested by studying with non-specific bacteria including E. coli and S. aureus that revealed only 2.01% and 2.66% binding when compared to the target bacterium. On the other hand, the quantification of Salmonella DNA was investigated in a concentration range of 0.002⁻200 µM using the developed DNA biosensor that demonstrated very high specificity and sensitivity with a detection limit of 0.94 nM. Our custom-designed microfluidic sensor offers rapid, highly sensitive, and specific diagnostic assay approaches for pathogen detection.