Applications of gold nanoparticles in ELISA, PCR, and immuno-PCR assays: A review

Immuno-PCR: A high-sensitivity approach for biomarker analysis

The integration of immunology and molecular biology, Immuno-Polymerase Chain Reaction, ie, Immuno-PCR, (iPCR), is an innovative cutting-edge detection strategy that holds significant promise for the identification of pathophysiologic biomarkers present at very low concentration or those inherently unstable. iPCR, known for superior sensitivity and specificity, has proven valuable in early disease diagnosis, monitoring and prognosis. This review summarizes the current applications of iPCR in detecting various disease biomarkers including those related to cancer, infection, autoimmune, cardiovascular, and neurological disease. We introduce the principle, advantages and limitations, specific applications, and clinical significance of iPCR, thereby promoting the widespread application of this technology in disease diagnosis. This technology facilitates early detection and intervention, enhances patient outcomes and survival rates, and is a valuable reference for future research and applications.

Nanopore-based enzyme-linked immunosorbent assay for cancer biomarker detection

Enzyme-linked immunosorbent assay (ELISA) has been widely used in cancer diagnostics due to its specificity, sensitivity and high throughput. However, conventional ELISA is semiquantitative and has an insufficiently low detection limit for applications requiring ultrahigh sensitivity. In this study, we developed an α-hemolysin-nanopore-based ELISA for detecting cancer biomarkers. After forming the immuno-sandwich complex, peptide probes carrying enzymatic cleavage sites are introduced, where they interact with enzymes conjugated to the detection antibodies within the complex. These probes generate distinct current signatures when translocated through the nanopore after enzymatic cleavage, enabling precise biomarker quantification. This approach offers a low detection limit of up to 0.03 fg ml-1 and the simultaneous detection of six biomarkers, including antigen and antibody biomarkers in blood samples. Overall, the nanopore-based ELISA demonstrates high sensitivity and multiplexing capability, making it suitable for next-generation diagnostic and point-of-care testing applications.

Nanoparticle-assisted PCR: fundamentals, mechanisms, and forensic implications

Polymerase Chain Reaction (PCR) has transformed forensic DNA analysis but is still limited when dealing with compromised trace or inhibitor-containing samples. Nanotechnology has been integrated into nanoPCR (nanoparticle-assisted PCR) to overcome these obstacles. Nanomaterials improve PCR sensitivity, selectivity, and efficiency. Examples of these materials are semiconductor quantum dots and metal nanoparticles. They enhance DNA binding to primers, stabilize enzymes, and function as effective heat conductors, making accurate amplification possible even with tainted samples. The developments in nanoPCR have potential uses in forensics, as they allow for the more sensitive analysis of smaller, polluted, or deteriorated samples. Nevertheless, there are methodological and ethical issues. To provide credible and legitimate forensic evidence, rigorous validation and standardization of NanoPCR techniques are vital. The article addresses the relevant ethical and methodological aspects in forensic casework while examining the integration of nanotechnology into PCR.

Machine Learning Interpretation of Optical Spectroscopy Using Peak-Sensitive Logistic Regression

Optical spectroscopy, a noninvasive molecular sensing technique, offers valuable insights into material characterization, molecule identification, and biosample analysis. Despite the informativeness of high-dimensional optical spectra, their interpretation remains a challenge. Machine learning methods have gained prominence in spectral analyses, efficiently unveiling analyte compositions. However, these methods still face challenges in interpretability, particularly in generating clear feature importance maps that highlight the spectral features specific to each class of data. These limitations arise from feature noise, model complexity, and the lack of optimization for spectroscopy. In this work, we introduce a machine learning algorithm─logistic regression with peak-sensitive elastic-net regularization (PSE-LR)─tailored for spectral analysis. PSE-LR enables classification and interpretability by producing a peak-sensitive feature importance map, achieving an F1-score of 0.93 and a feature sensitivity of 1.0. Its performance is compared with other methods, including k-nearest neighbors (KNN), elastic-net logistic regression (E-LR), support vector machine (SVM), principal component analysis followed by linear discriminant analysis (PCA-LDA), XGBoost, and neural network (NN). Applying PSE-LR to Raman and photoluminescence (PL) spectra, we detected the receptor-binding domain (RBD) of SARS-CoV-2 spike protein in ultralow concentrations, identified neuroprotective solution (NPS) in brain samples, recognized WS2 monolayer and WSe2/WS2 heterobilayer, analyzed Alzheimer's disease (AD) brains, and suggested potential disease biomarkers. Our findings demonstrate PSE-LR's utility in detecting subtle spectral features and generating interpretable feature importance maps. It is beneficial for the spectral characterization of materials, molecules, and biosamples and applicable to other spectroscopic methods. This work also facilitates the development of nanodevices such as nanosensors and miniaturized spectrometers based on nanomaterials.

Synergistic effect between bacteriophages and nanozymes for hybrid dual recognition of pathogenic bacteria from water, food, and agricultural samples: promising new tools for sensitive and specific biosensing

Worldwide, pathogenic bacteria are among the most significant causes of infections. Indeed, delays in diagnosis and detection of these bacteria result in high morbidity and mortality rates and detection platforms must be developed to overcome these challenges. Biosensors, as high-potential analytical tools, can play an important role in the detection of pathogenic bacteria. The application of nanozymes as nanomaterial-based artificial enzymes in the structure of biosensors can overcome the limitations of common biological elements. Furthermore, the integration of bacteriophages, as novel bioreceptors, with nanozymes enabled a clear distinction between viable and dead bacteria. The application of bacteriophage-nanozyme as hybrid probes in biosensors can boost pathogenic bacteria detection. In this review, the effects of different nanozymes, including metal-based, metal oxide-based, and metal-organic framework (MOF)-based nanozymes, after integration with bacteriophages are discussed. Perspectives and challenges of a combination of these novel bioreceptors and nanomaterial-based artificial enzymes are presented for detecting various pathogenic bacteria.

Double antibody sandwich ELISA based on rabbit monoclonal antibody targeting gD protein for the detection of bovine herpesvirus 1

Bovine herpesvirus 1 (BHV-1) is a highly contagious and latent virus that induces various diseases in the respiratory and reproductive systems. It is widespread in numerous countries, including China, and has a high positive detection rate, causing significant economic losses to global cattle industry. Timely and precise diagnosis is essential for effective preventative and control strategies. This study constructed a rabbit phage single chain fragment variable (scFv) display library with 7.14 × 1010 cfu/mL based on BHV-1 gD protein expressed in a prokaryotic system. Following three rounds of biopanning, three high-affinity scFv targeting the gD protein were obtained, and CHO-K1 cells were employed to express three high-affinity secreted rabbit monoclonal antibodies (RmAb). Double antibody sandwich enzyme-linked immunosorbent assay (DAS-ELISA) was established with D3 as the capture antibody and D2 as the detection antibody. The findings indicated that optimal reaction conditions were: 3 % BSA blocking, 90 min antigen incubation time, 15 min color development time, and a cutoff value of 0.8525. The specificity test demonstrated that the method exclusively responded with BHV-1, exhibiting no cross-reactivity with other bovine-related viruses. Additionally, the coefficients of variation between Intra-batch and Inter-batch were below 5 %, indicating good stability and reliability. This study is the first application of RmAb in developing a detection method for BHV-1, aimed at improving the specificity and sensitivity of the method, thereby offering robust scientific technical assistance for the epidemiological surveillance and prevention of this disease.

Cavity Effect of Gold Nanoparticles on Mid-Infrared Light

Nanophotonics has attracted wide attention in photonic devices and biotechnology. Interaction of visible and near-infrared lights with metal nanoparticles (NPs) is already well explored, leading to a mount of applications, especially in high-sensitivity biodetection. However, the effects of metal NPs on mid-infrared (MIR) light are still lacking because the light cannot resonantly excite the surface electron oscillation of the NPs. Recently, gold NP (AuNP)-assisted experiments indicate that AuNPs can be used in the detection of MIR biophotons, but the underlying mechanism remains unclear. Here, constructing a cavity by two AuNPs and performing finite difference time domain simulations based on Maxwell equations, we demonstrate that even if the AuNP dimension is significantly smaller than the MIR wavelength, the AuNP-formed cavity (AuNP-cavity) still can confine the light. The confinement effect increases with an increase in the wavelength or the cavity length when the cavity length and wavelength are fixed, respectively, while it vanishes only when the AuNP dimension is less than 1000th of the light wavelength. These results can be attributed to the resonance of MIR light with the two AuNPs, and in this view, it can be said that this nanocavity overcomes the diffraction limitation of the optical system. Our findings provide an understanding of the biophoton detection mentioned above, potentially promoting the applications of metal NPs in biotechnology and even in MIR-related imaging and wave-guiding circuits.

Tetrahedral DNA nanostructures-assisted electrochemical assay for detecting circulating tumor DNA by combining a masking tactic with 3D-hybridization chain reactions

Circulating tumor DNA (ctDNA) is a remarkable noninvasive tumor marker that plays a crucial role in tumor diagnosis, prognosis and treatment. However, detecting low-abundance ctDNA from a substantial amount of nucleic acids originating from healthy cells is challenging. Herein, we proposed a tetrahedral DNA nanostructures (TDNs)-assisted electrochemical biosensor for ctDNA detection. This biosensor combines a masking tactic with 3D-hybridization chain reactions. Masking hairpins (MHs) were initially introduced to prevent interference from wild-type (WT) DNA. Then, the initiator sequence was transferred to the electrode surface modified with TDNs by the target ctDNA. The initiator sequence triggers the 3D self-assembly of hairpin strands, leading to the formation of DNA networks or even DNA hydrogels (long reaction time). This process generates numerous evenly distributed biotin molecules that can bind to streptavidin peroxidase to considerably amplify the signal. This method exhibits high sensitivity (the minimum concentration for detecting ctDNA is 1 aM, which corresponds to 60 ctDNA molecules in 100 μl sample) and excellent specificity (single mismatch). More importantly, this high-performance sensor can detect ctDNA with other mutation sites and their mixtures by modifying the corresponding capture probes on the TDNs. Furthermore, this ultrasensitive sensor effectively detects target ctDNA (0.001 %) at high levels of WT DNA and in complex matrices such as serum. These findings suggest that the sensor has promising potential as a noninvasive tool for early tumor diagnosis.

Harnessing the power of inorganic nanoparticles for the management of TNBC

Triple-negative breast cancer (TNBC) is a highly aggressive and metastatic form of breast cancer characterized by the absence of hormonal receptors with a poor prognosis and limited treatment options. Addressing this challenge has become an urgent priority, driving substantial scientific efforts in this area. In recent years, inorganic nanoparticles have emerged as promising agents for the therapeutic and diagnostic management of this malignancy. Their unique physicochemical properties such as exceptional stability, uniform size, ease of surface functionalization, and distinctive optical and magnetic characteristics have positioned them as highly attractive candidates for these applications. This review primarily focuses on the therapeutic and diagnostic applications of inorganic nanoparticles, summarizing key research findings that demonstrate their efficacy against TNBC. Additionally, it addresses the toxicological concerns associated with these nanoparticles and explores advanced strategies to mitigate their adverse effects, thereby improving their clinical utility. Finally, the review concludes with a concise discussion of the prospects of these nanoparticles in biomedicine.

Advances in molecular epidemiology and detection methods of pseudorabies virus

Pseudorabies (PR), a highly contagious disease caused by the pseudorabies virus (PRV), represents a significant threat to the global swine industry. Despite the success of developed countries in controlling the PRV epidemic through swine pseudorabies eradication programs, wild boars, as a potential source of infection, still require sustained attention and effective control measures. Concurrently, there has been considerable global attention directed towards cases of PRV infection in humans. In consideration of the aforementioned factors, this paper presents a comprehensive review of recent developments in the PRV genome, epidemiology, vaccine research, and molecular detection methods. The epidemiology section presents an analysis of the transmission routes, susceptible animal groups, and geographic distribution of PRV, as well as an examination of the trend of the epidemic in recent years. In the field of vaccine research, the current development of genetically engineered vaccines is emphasized, and the immunogenicity and safety of vaccines are discussed. Moreover, the molecular detection techniques utilized to identify PRV, including immunological methods, nucleic acid detection methods, biosensors, and so forth, are presented in a systematic manner. Finally, this paper presents a comprehensive discussion of the current status of PRV-related research and offers insights into future directions, with the aim of providing a foundation for the scientific prevention and control of PRV.

The outputs of molecular sensors detectable by human senses

Molecular sensors respond to the presence of biological analytes by producing signals that are either directly perceivable by human sensory systems or converted into electric signals, which require electronic devices for communicating the signals to humans. Here, we review the outputs of molecular sensors detectable directly by human senses. According to the literature, sensors with visual outputs dominate. Undeservedly unnoticed, sensors that release gases might be particularly useful since the gas output can be detected with the several human senses in a quantifiable format. Relatively new sensors with tactile outputs can be accessed by visually impaired people. Molecular sensors communicating their outputs directly to human senses bypassing electronic devices may contribute to the development of point-of-care testing technologies, as well as providing the direct communication of molecular nanorobots with humans.

Nanoparticle-based colorimetric assays for early and rapid screening of the oncogenic HPV variants 16 and 18

Cervical cancer is predominantly caused by human papillomavirus (HPV), with oncogenic strains HPV 16 and 18 accounting for most cases worldwide. Prompt and precise identification of these high-risk HPV types is essential for enhancing patient outcomes as it enables timely intervention and management. However, the existing HPV detection techniques are time-consuming, expensive, and require highly skilled personnel. This study presents the development and evaluation of a colorimetric nanosensor for the rapid detection of high-risk human papillomavirus (HPV) variants 16 and 18. Gold nanoparticles (AuNPs) were synthesized using an optimized method based on response surface methodology and then functionalized with monoclonal antibodies specific to HPV16-L1 and HPV18-L1 proteins. The nanosensor exhibited a visible color shift from red to violet upon the detection of the target proteins. The analytical validation demonstrated good linearity, sensitivity, precision, accuracy, robustness, and selectivity for detecting recombinant HPV16-L1 and HPV18-L1 proteins. The nanosensor remained stable for at least 90 days when stored at 4 °C. Clinical evaluation of 173 patients, obtained from cervical samples, showed high specificity (77.8 % for HPV16 and 87.3 % for HPV18) and excellent negative predictive value (>96 % for both). Several false-positive results have been associated with other HPV variants or cervical abnormalities. While the sensitivity was limited by the low prevalence of positive samples, the simple, rapid, and equipment-free nature of this colorimetric nanosensor makes it a promising tool for HPV screening, especially in resource-limited settings.

New insights into gold nanoparticles in virology: A review of their applications in the prevention, detection, and treatment of viral infections

Viral infections have led to the deaths of millions worldwide and come with significant economic and social burdens. Emerging viral infections, as witnessed with coronavirus disease 2019 (COVID-19), can profoundly affect all aspects of human life, highlighting the imperative need to develop diagnostic, therapeutic, and effective control strategies in response. Numerous studies highlight the diverse applications of nanoparticles in diagnosing, controlling, preventing, and treating viral infections. Due to favorable and flexible physicochemical properties, small size, immunogenicity, biocompatibility, high surface-to-volume ratio, and the ability to combine with antiviral agents, gold nanoparticles (AuNPs) have shown great potential in the fight against viruses. The physical and chemical properties, the adjustability of characteristics based on the type of application, the ability to cross the blood-brain barrier, the ability to infiltrate cells such as phagocytic and dendritic cells, and compatibility for complexing with various compounds, among other features, transform AuNPs into a suitable tool for combating and addressing pathogenic viral agents through multiple applications. In recent years, AuNPs have been employed in various applications to fight viral infections. However, a comprehensive review article on the applications of AuNPs against viral infections has yet to be available. Given their versatility, AuNPs present an appealing option to address various gaps in combating viral infections. Hence, this review explores the attributes, antiviral properties, contributions to drug delivery, vaccine development, and diagnostic uses of AuNPs.

Detection of MPT-64 protein in pleural tuberculosis cases by magnetic bead-gold nanoparticle-PCR amplified immunoassay

AIM

Diagnosis of pleural tuberculosis (TB) is challenging; thus, an efficient method is urgently needed.

METHODS

We developed a magnetic-bead-gold nanoparticle-PCR amplified immunoassay (MB-AuNP-I-PCR, liquid system) to detect the Mycobacterium tuberculosis MPT-64 protein in pleural TB patients. AuNPs functionalized with detection antibodies/oligonucleotides were characterized by UV-vis spectroscopy, Transmission/Scanning electron microscopy, Fourier-transform infrared spectrometer, ELISA, and PCR, whereas MBs conjugated with detection antibodies were validated by magneto-ELISA/UV-vis spectroscopy.

RESULTS

We utilized the MB-AuNP-I-PCR for MPT-64 detection in 99 clinical specimens which displayed 85.2% sensitivity and 97.8% specificity to diagnose pleural TB cases. Markedly, the sensitivity achieved by MB-AuNP-I-PCR was noticeably higher (p < 0.01) than magneto-ELISA and GeneXpert.

CONCLUSION

This is a preliminary report to diagnose pleural TB cases by MB-AuNP-I-PCR with promising results that require further corroboration in a higher number of specimens.

Integration of silver nanostructures in wireless sensor networks for enhanced biochemical sensing

Integrating noble metal nanostructures, specifically silver nanoparticles, into sensor designs has proven to enhance sensor performance across key metrics, including response time, stability, and sensitivity. However, a critical gap remains in understanding the unique contributions of various synthesis parameters on these enhancements. This study addresses this gap by examining how factors such as temperature, growth time, and choice of capping agents influence nanostructure shape and size, optimizing sensor performance for diverse conditions. Using silver nitrate and sodium borohydride, silver seed particles were created, followed by controlled growth in a solution containing additional silver ions. The size and morphology of the resulting nanostructures were regulated to achieve optimal properties for biochemical sensing in wireless sensor networks. Results demonstrated that embedding these nanostructures in Polyvinyl Alcohol (PVA) matrices led to superior stability, maintaining 93% effectiveness over 30 days compared to 70% in Polyethylene Glycol (PEG). Performance metrics revealed significant improvements: reduced response times (1.2 ms vs. 1.5 ms at zero analyte concentration) and faster responses at higher analyte levels (0.2 ms). These outcomes confirm that higher synthesis temperatures and precise shape control contribute to larger, more stable nanostructures.The enhanced stability and responsiveness underscore the potential of noble metal nanostructures for scalable and durable sensor applications, offering a significant advancement over current methods.

Constructions, Purifications and Applications of DNA-Antibody Conjugates: A Review

A DNA-antibody conjugate is a synthetic molecule that combines the unique functions of both an antibody and DNA. With the increased accessibility of commercialized kits, the procedure for constructing conjugates is simplified and the requirement for chemistry background is reduced. As a result, the difficulty of preparing a DNA-antibody conjugate has been significantly lowered. Therefore, the application of DNA-antibody conjugates has attracted more interest in recent years. The most common application of DNA-antibody conjugates is based on the amplifiable property of DNA through PCR. This includes single-conjugate-based immuno-PCR, paired-conjugates-based proximity ligation assay, and proximity extension assay. These methods achieve highly sensitive or specific detection of target proteins. The conjugated single stranded DNA molecules can also specifically hybridize with another strand containing its complementary sequence. This property can be used to selectively bind fluorophore labeled DNA strands, which plays an important role in tissue imaging and spatial omics. All these factors make DNA-antibody conjugates have a broad range of applications in research, diagnosis, and potentially therapy.

Can nanotechnology and genomics innovations trigger agricultural revolution and sustainable development?

At the dawn of new millennium, policy makers and researchers focused on sustainable agricultural growth, aiming for food security and enhanced food quality. Several emerging scientific innovations hold the promise to meet the future challenges. Nanotechnology presents a promising avenue to tackle the diverse challenges in agriculture. By leveraging nanomaterials, including nano fertilizers, pesticides, and sensors, it provides targeted delivery methods, enhancing efficacy in both crop production and protection. This integration of nanotechnology with agriculture introduces innovations like disease diagnostics, improved nutrient uptake in plants, and advanced delivery systems for agrochemicals. These precision-based approaches not only optimize resource utilization but also reduce environmental impact, aligning well with sustainability objectives. Concurrently, genetic innovations, including genome editing and advanced breeding techniques, enable the development of crops with improved yield, resilience, and nutritional content. The emergence of precision gene-editing technologies, exemplified by CRISPR/Cas9, can transform the realm of genetic modification and enabled precise manipulation of plant genomes while avoiding the incorporation of external DNAs. Integration of nanotechnology and genetic innovations in agriculture presents a transformative approach. Leveraging nanoparticles for targeted genetic modifications, nanosensors for early plant health monitoring, and precision nanomaterials for controlled delivery of inputs offers a sustainable pathway towards enhanced crop productivity, resource efficiency, and food safety throughout the agricultural lifecycle. This comprehensive review outlines the pivotal role of nanotechnology in precision agriculture, emphasizing soil health improvement, stress resilience against biotic and abiotic factors, environmental sustainability, and genetic engineering.

Proposal of a Rapid Detection System Using Image Analysis for ELISA with an Autonomous Centrifugal Microfluidic System

In this study, with the aim of adapting an enzyme-linked immunosorbent assay (ELISA) system for point-of-care testing (POCT), we propose an image analysis method for ELISAs using a centrifugal microfluidic device that automatically executes the assay. The developed image analysis method can be used to quantify the color development reaction on a TMB (3,3',5,5'-tetramethylbenzidine) substrate. In a conventional ELISA, reaction stopping reagents are required at the end of the TMB reaction. In contrast, the developed image analysis method can analyze color in the color-developing reaction without a reaction stopping reagent. This contributes to a reduction in total assay time. The microfluidic devices used in this study could execute reagent control for ELISAs by steady rotation. In the demonstration of the assay and image analysis, a calibration curve for mouse IgG detection was successfully prepared, and it was confirmed that the image analysis method had the same performance as the conventional analysis method. Moreover, the changes in the amount of color over time confirmed that a calibration curve equal to the endpoint analysis was obtained within 2 min from the start of the TMB reaction. As the assay time before the TMB reaction was approximately 7.5 min, the developed ELISA system could detect TMB in just 10 min. In conventional methods using a plate reader, the assay required a time of 90 min for manual handling using microwell plates, and in the case of using automatic microfluidic devices, 30 min were required. The time of 10 min realized by this proposed method is equal to the time required for detection in an immunochromatographic assay with a lateral flow assay; therefore, it is expected that ELISAs can be performed sufficiently to adapt to POCT.

Biotechnological advances in microbial synthesis of gold nanoparticles: Optimizations and applications

This review discusses the eco-friendly and cost-effective biosynthesis of gold nanoparticles (AuNPs) in viable microorganisms, focusing on microbes-mediated AuNP biosynthesis. This process suits agricultural, environmental, and biomedical applications, offering renewable, eco-friendly, non-toxic, sustainable, and time-efficient methods. Microorganisms are increasingly used in green technology, nanotechnology, and RNAi technology, but several microorganisms have not been fully identified and characterized. Bio-nanotechnology offers eco-friendly and sustainable solutions for nanomedicine, with microbe-mediated nanoparticle biosynthesis producing AuNPs with anti-oxidation activity, stability, and biocompatibility. Ultrasmall AuNPs offer rapid distribution, renal clearance, and enhanced permeability in biomedical applications. The review explores nano-size dependent biosynthesis of AuNPs by bacteria, fungi, and viruses revealing their non-toxic, non-genotoxic, and non-oxidative properties on human cells. AuNPs with varying sizes and shapes, from nitrate reductase enzymes, have shown potential as a promising nano-catalyst. The synthesized AuNPs, with negative charge capping molecules, have demonstrated antibacterial activity against drug-resistant Pseudomonas aeruginosa, and Acinetobacter baumannii strains, and were non-toxic to Vero cell lines, indicating potential antibiotic resistance treatments. A green chemical method for the biosynthesis of AuNPs using reducing chloroauric acid and Rhizopus oryzae protein extract has been described, demonstrating excellent stability and strong catalytic activity. AuNPs are eco-friendly, non-toxic, and time-efficient, making them ideal for biomedical applications due to their antioxidant, antidiabetic, and antibacterial properties. In addition to the biomedical application, the review also highlights the role of microbially synthesized AuNPs in sustainable management of plant diseases, and environmental bioremediation.

Rapid Real-Time PCR Based on Core-Shell Tecto-Dendrimer-Entrapped Au Nanoparticles

Rapid real-time PCR (generally <1 h) has broad prospects. In this study, we synthesized a new type of nanomaterial core-shell tecto-dendrimer coated with Au nanoparticles (Au CSTDs) for research in this field. The experimental results showed that Au CSTDs could significantly shorten the time of real-time PCR (from 72 to 28 min) with different templates, while the detection limit reached 10 copies and the nonspecific amplification was significantly reduced. Furthermore, experimental analyses and theoretical studies using the finite element simulation method confirmed that Au CSTDs function by synergistically enhancing electrostatic adsorption and thermal conductivity. These properties play a key role in improving real-time PCR, especially in particle-particle interactions. This study contributes an advanced method to rapid real-time PCR, which is expected to remarkably improve the efficiency, lower the detection limit, and enhance the specificity of molecular detection.

Enhancing the sensitivity of immunomagnetic assay for 3-phenoxybenzonic acid: a novel approach utilizing magnetosome-nanobody complexes and gold nanoparticles probes

The 3-phenoxybenzoic acid (3-PBA) residues in environment are posing a significant challenge to our daily lives. To establish a more sensitive and rapid detection method, anti-3-PBA nanobodies (Nbs) were immobilized onto magnetosomes (bacterial magnetic nanoparticles, termed as BMPs), forming a robust BMP-Nb complex. The 3-PBA derivative was labeled with horseradish peroxidase (HRP) and further associated with gold nanoparticles (AuNPs) to create a highly sensitive probe (3-PBA-HRP-AuNP). An innovative immunoassay that combined BMP-Nb complex with 3-PBA-HRP-AuNP was developed for determinaton of 3-PBA. This method enabled the determination of 3-PBA with a half-maximum signal inhibition concentration (IC50) of 1.03 ng/mL, which was more sensitive than that of using 3-PBA-HRP as tracer with an IC50 of 2.18 ng/mL. The reliability of the assay was evidenced by the quantitative recovery of 3-PBA from water and soil samples ranging from 76.85 to 95.64%. The 3-PBA residues determined by this assay in actual water samples were between < LOD and 2.54 ng/mL and were between < LOD and 11.25 ng/g (dw) in real soils, respectively, which agreed well with those of liquid chromatography mass spectrometry (LC-MS). Collectively, the BMP-Nb and 3-PBA-HRP-AuNP-based immunoassay provides a powerful tool for the precise detection of 3-PBA residues in environment matrices, reinforcing our capacity to monitor and mitigate potential ecological and health impacts associated with this prevalent pollutant.

A review: early detection of oral cancer biomarkers using microfluidic colorimetric point-of-care devices

Oral squamous cell carcinoma (OSCC) is the most common type of head and neck cancers. OSCC constitutes 90% of the head and neck malignancies. The delayed identification of oral cancer is the primary cause of ineffective medical treatment. To address this issue, low-cost, reliable point-of-care devices that can be utilized for large-scale screening, even in low-resource settings, including rural areas and primary healthcare centers, are of great interest. Herein, a comprehensive analysis of numerous salivary biomarkers that exhibit significant variations in concentration between individuals with oral cancer and those without is given. Furthermore, the article explores several point-of-care devices that exhibit potential in the realm of oral cancer detection. The biomarkers are discussed with a focus on their structural characteristics and role in oral cancer progression. The devices based on colorimetry and microfluidics are discussed in detail, considering their compliance with the 'REASSURED' criteria given by the World Health Organization (WHO) and suitability for mass screening in low-resource settings. Finally, the discourse revolves around the fundamental aspects pertaining to the advancement of multiplex, cost-effective point-of-care devices designed for widespread screening purposes.

Detection methods for antibiotics in wastewater: a review

Antibiotics are widely used as fungicides because of their antibacterial and bactericidal effects. However, it is necessary to control their dosage. If the amount of antbiotics is too much, it cannot be completely metabolized and absorbed, will pollute the environment, and have a great impact on human health. Many antibiotics usually left in factory or aquaculture wastewater pollute the environment, so it is vital to detect the content of antibiotics in wastewater. This article summarizes several common methods of antibiotic detection and pretreatment steps. The detection methods of antibiotics in wastewater mainly include immunoassay, instrumental analysis method, and sensor. Studies have shown that immunoassay can detect deficient concentrations of antibiotics, but it is affected by external factors leading to errors. The detection speed of the instrumental analysis method is fast, but the repeatability is poor, the price is high, and the operation is complicated. The sensor is a method that is currently increasingly studied, including electrochemical sensors, optical sensors, biosensors, photoelectrochemical sensors, and surface plasmon resonance sensors. It has the advantages of fast detection speed, high accuracy, and strong sensitivity. However, the reproducibility and stability of the sensor are poor. At present, there is no method that can comprehensively integrate the advantages. This paper aims to review the enrichment and detection methods of antibiotics in wastewater from 2020 to the present. It also aims to provide some ideas for future research directions in this field.

Smartphone-enabled colorimetric immunoassay for deoxynivalenol based on Mn2+-mediated aggregation of AuNPs

Deoxynivalenol (DON) is a common mycotoxin in food that mainly pollutes grain crops and feeds, such as barley, wheat and corn. DON has caused widespread concern in the field of food and feed safety. In this study, a colorimetric immunoassay was proposed based on the aggregation of gold nanoparticles (AuNPs) due to the decomposition of Mn2+ from gold-coated manganese dioxide (AuNP@MnO2) nanosheets. In this study, 2-(dihydrogen phosphate)-l-ascorbic acid (AAP) was hydrolyzed by alkaline phosphatase (ALP) and converted to ascorbic acid (AA). Then, AuNP@MnO2 was reduced to Mn2+ and AuNPs aggregation occurred. Using the unique optical characteristics of AuNPs and AuNP@MnO2, visible color changes realized simple detection of DON with high sensitivity and portability. With increasing DON content, the color changed more obviously. To quantitatively detect DON, pictures can be taken and the blue value can be read by a smartphone. The detection limit (Ic10) of this method was 0.098 ng mL-1, which was 326 times higher than that of traditional competitive ELISA, and the detection range was 0.177-6.073 ng mL-1. This method exhibited high specificity with no cross-reaction in other structural analogs. The average recovery rate of DON in corn flour samples was 89.1 %-110.2 %, demonstrating the high accuracy and stability of this assay in actual sample detection. Therefore, the colorimetric immunoassay can be used for DON-related food safety monitoring.

Research progress of nanoparticles in diagnosis and treatment of hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is among the most common malignant liver tumors. Despite progress in anticancer drugs and surgical approaches, early detection of HCC remains challenging, often leading to late-stage diagnosis where rapid disease progression precludes surgical intervention, leaving chemotherapy as the only option. However, the systemic toxicity, low bioavailability, and significant adverse effects of chemotherapy drugs often lead to resistance, rendering treatments ineffective for many patients. This article outlines how nanoparticles, following functional modification, offer high sensitivity, reduced drug toxicity, and extended duration of action, enabling precise targeting of drugs to HCC tissues. Combined with other therapeutic modalities and imaging techniques, this significantly enhances the diagnosis, treatment, and long-term prognosis of HCC. The advent of nanomedicine provides new methodologies and strategies for the precise diagnosis and integrated treatment of HCC.

Recent advances and challenges in plant viral diagnostics

Accurate and timely diagnosis of plant viral infections plays a key role in effective disease control and maintaining agricultural productivity. Recent advances in the diagnosis of plant viruses have significantly expanded our ability to detect and monitor viral pathogens in agricultural crops. This review discusses the latest advances in diagnostic technologies, including both traditional methods and the latest innovations. Conventional methods such as enzyme-linked immunosorbent assay and DNA amplification-based assays remain widely used due to their reliability and accuracy. However, diagnostics such as next-generation sequencing and CRISPR-based detection offer faster, more sensitive and specific virus detection. The review highlights the main advantages and limitations of detection systems used in plant viral diagnostics including conventional methods, biosensor technologies and advanced sequence-based techniques. In addition, it also discusses the effectiveness of commercially available diagnostic tools and challenges facing modern diagnostic techniques as well as future directions for improving informed disease management strategies. Understanding the main features of available diagnostic methodologies would enable stakeholders to choose optimal management strategies against viral threats and ensure global food security.

Operation-friendly and accurate naked-eye observation assay for fast zoonotic echinococcosis and pulmonary tuberculosis monitoring in clinics

Echinococcosis and tuberculosis are two common zoonotic diseases that can cause severe pulmonary infections. Early screening and treatment monitoring are of great significance, especially in areas with limited medical resources. Herein, we designed an operation-friendly and rapid magnetic enrichment-silver acetylene chromogenic immunoassay (Me-Sacia) to monitor the antibody. The main components included secondary antibody-modified magnetic nanoparticles (MNP-Ab2) as capture nanoparticles, specific peptide (EG95 or CFP10)-modified silver nanoparticles (AgNP-PTs) as detection nanoparticles, and alkyne-modified gold nanoflowers as chromogenic nanoparticles. Based on the magnetic separation and plasma luminescence techniques, Me-Sacia could completely replace the colorimetric assay of biological enzymes. It reduced the detection time to approximately 1 h and simplified the labor-intensive and equipment-intensive processes associated with conventional ELISA. Meanwhile, the Me-Sacia showed universality for various blood samples and intuitive observation with the naked eye. Compared to conventional ELISA, Me-Sacia lowered the detection limit by approximately 96.8 %, increased the overall speed by approximately 15 times, and improved sensitivity by approximately 7.2 %, with a 100 % specificity and a coefficient of variation (CV) of less than 15 %.

Quantitative reagent monitoring in paper-based electrochemical rapid diagnostic tests

Paper-based rapid diagnostic tests (RDTs) are an essential component of modern healthcare, particularly for the management of infectious diseases. Despite their utility, these capillary-driven RDTs are compromised by high failure rates, primarily caused by user error. This limits their utility in complex assays that require multiple user operations. Here, we demonstrate how this issue can be directly addressed through continuous electrochemical monitoring of reagent flow inside an RDT using embedded graphenized electrodes. Our method relies on applying short voltage pulses and measuring variations in capacitive discharge currents to precisely determine the flow times of injected samples and reagents. This information is reported to the user, guiding them through the testing process, highlighting failure cases and ultimately decreasing errors. Significantly, the same electrodes can be used to quantify electrochemical signals from immunoassays, providing an integrated solution for both monitoring assays and reporting results. We demonstrate the applicability of this approach in a serology test for the detection of anti-SARS-CoV-2 IgG in clinical serum samples. This method paves the way towards "smart" RDTs able to continuously monitor the testing process and improve the robustness of point-of-care diagnostics.

To see or not to see: In vivo nanocarrier detection methods in the brain and their challenges

Nanoparticles have a great potential to significantly improve the delivery of therapeutics to the brain and may also be equipped with properties to investigate brain function. The brain, being a highly complex organ shielded by selective barriers, requires its own specialized detection system. However, a significant hurdle to achieve these goals is still the identification of individual nanoparticles within the brain with sufficient cellular, subcellular, and temporal resolution. This review aims to provide a comprehensive summary of the current knowledge on detection systems for tracking nanoparticles across the blood-brain barrier and within the brain. We discuss commonly employed in vivo and ex vivo nanoparticle identification and quantification methods, as well as various imaging modalities able to detect nanoparticles in the brain. Advantages and weaknesses of these modalities as well as the biological factors that must be considered when interpreting results obtained through nanotechnologies are summarized. Finally, we critically evaluate the prevailing limitations of existing technologies and explore potential solutions.

Facile construction of sandwich ELISA based on double-nanobody for specific detection of α-hemolysin in food samples

α-hemolysin (Hla), a toxin secreted by Staphylococcus aureus (S. aureus), has been proved to be involved in the occurrence and aggravation of food poisoning. Hence, it is quite essential to establish its rapid detection methods to guarantee food safety. Sandwich ELISA based on nanobody is well known to be viable for toxins, but there is absence of nanobody against Hla, let alone a pair for it. Therefore, in this paper, we screened specific nanobodies by bio-panning and obtained the optimal nanobody pair for sandwich ELISA firstly. Then, RANbody, a novel nanobody owning both recognition and catalytic capability, is generated in a single step and at low cost through molecular recombination technology. Subsequently, sandwich ELISA was developed to detect Hla based on the nanobody and RANbody, that not only eliminated the use of secondary antibodies and animal-derived antibody, but also reduced detection time and cost, compared with traditional sandwich ELISA. Lastly, the performance has been evaluated, especially for specificity which showed no response to other hemolysins and a low limit of detection of 10 ng/mL. Besides, the proposed sandwich ELISA exhibits favorable feasibility and was successfully employed for the detection of Hla in milk and pork samples.

Cas12a/Guide RNA-Based Platform for Rapidly and Accurately Detecting blaKPC Gene in Carbapenem-Resistant Enterobacterales

Purpose

Accurate detection and identification of pathogens and their associated resistance mechanisms are essential prerequisites for implementing precision medicine in the management of Carbapenem-resistant Enterobacterales (CRE). Among the various resistance mechanisms, the production of KPC carbapenemase is the most prevalent worldwide. Consequently, this study aims to develop a convenient and precise nucleic acid detection platform specifically for the blaKPC gene.

Methods

The initial phase of our research methodology involved developing a CRISPR/Cas12a detection framework, which was achieved by designing highly specific single-guide RNAs (sgRNAs) targeting the blaKPC gene. To enhance the sensitivity of this system, we incorporated three distinct amplification techniques-polymerase chain reaction (PCR), loop-mediated isothermal amplification (LAMP), and recombinase polymerase amplification (RPA)-into the CRISPR/Cas12a framework. Subsequently, we conducted a comparative analysis of the sensitivity and specificity of these three amplification methods when used in combination with the CRISPR/Cas12a system. Additionally, we assessed the clinical applicability of the methodologies by evaluating fluorescence readouts from 80 different clinical isolates. Furthermore, we employed lateral flow assay technology to provide a visual representation of the results, facilitating point-of-care testing.

Results

Following a comparative analysis of the sensitivity and specificity of the three methods, we identified the RPA-Cas12a approach as the optimal detection technique. Our findings demonstrated that the limit of detection (LoD) of the RPA-Cas12a platform was 1 aM (~1 copy/µL) for plasmid DNA and 5 × 10³ fg/µL for genomic DNA. Furthermore, both the sensitivity and specificity of the platform achieved 100% upon validation with 80 clinical isolates.

Conclusion

These findings suggest that the developed RPA-Cas12a platform represents a promising tool for the cost-effective, convenient, and accurate detection of the blaKPC gene.

Sensitive, Semiquantitative, and Portable Nucleic Acid Detection of Rabies Virus Using a Personal Glucose Meter

Rabies is a zoonotic infection with the potential to infect all mammals and poses a significant threat to mortality. Although enzyme-linked immunosorbent tests and real-time reverse transcription-quantitative polymerase chain reaction (RT-qPCR) have been established for rabies virus (RABV) detection, they require skilled staff. Here, we introduce a personal glucose meter (PGM)-based nucleic acid (NA-PGM) detection method to diagnose RABV. This method ensures sensitive and convenient RABV diagnosis through hybridization of reverse transcription-recombinase aided amplification (RT-RAA) amplicons with probes labeled with sucrose-converting enzymes, reaching a detection level as low as 6.3 copies/μL equivalent to 12.26 copies. NA-PGM allows for the differentiation of RABV from other closely related viruses. In addition, NA-PGM showed excellent performance on 65 clinical samples with a 100% accuracy rate compared with the widely adopted RT-qPCR method. Thus, our developed NA-PGM method stands out as sensitive, semiquantitative, and portable for RABV detection, showcasing promise as a versatile platform for a wide range of pathogens.

Classification and applications of nanomaterials in vitro diagnosis

With the rapid development of clinical diagnosis and treatment, many traditional and conventional in vitro diagnosis technologies are unable to meet the demands of clinical medicine development. In this situation, nanomaterials are rapidly developing and widely used in the field of in vitro diagnosis. Nanomaterials have distinct size-dependent physical or chemical properties, and their optical, magnetic, electrical, thermal, and biological properties can be modulated at the nanoscale by changing their size, shape, chemical composition, and surface functional groups, particularly because they have a larger specific surface area than macromaterials. They provide an amount of space to modify different molecules on their surface, allowing them to detect small substances, nucleic acids, proteins, and microorganisms. Combining nanomaterials with in vitro diagnosis is expected to result in lower detection limits, higher sensitivity, and stronger selectivity. In this review, we will discuss the classfication and properties of some common nanomaterials, as well as their applications in protein, nucleic acids, and other aspect detection and analysis for in vitro diagnosis, especially on aging-related nanodiagnostics. Finally, it is summarized with guidelines for in vitro diagnosis.

An isothermal nucleic acid amplification-based enzymatic recombinase amplification method for dual detection of porcine epidemic diarrhea virus and porcine rotavirus A

Viral diarrhea is the predominant digestive tract sickness in piglings, resulting in substantial profit losses in the porcine industry. Porcine rotavirus A (PoRVA) and porcine epidemic diarrhea virus (PEDV) are the main causes of grave gastroenteritis and massive dysentery, especially in piglets. PoRVA and PEDV have high transmissibility, exhibit similar clinical symptoms, and frequently co-occur. Therefore, to avoid financial losses, a quick, highly efficient, objective diagnostic test for the prevention and detection of these diseases is required. Enzymatic recombinase amplification (ERA) is a novel technology based on isothermal nucleic acid amplification. It demonstrates high sensitivity and excellent specificity, with a short processing time and easy operability, compared with other in vitro nucleic acid amplification technologies. In this study, a dual ERA method to detect and distinguish between PEDV and PoRVA nucleic acids was established. The method shows high sensitivity, as the detection limits were 101 copies/μL for both viruses. To test the usefulness of this method in clinical settings, we tested 64 swine clinical samples. Our results were 100% matched with those acquired using a commercially available kit. Therefore, we have successfully developed a dual diagnostic ERA nucleic acids method for detecting and distinguishing between PEDV and PoRVA.

Identification of Microorganism in Infected Wounds by Positively Charged Selective Sensor Array and Deep Learning Algorithm

Microorganism are ubiquitous and intimately connected with human health and disease management. The accurate and fast identification of pathogenic microorganisms is especially important for diagnosing infections. Herein, three tetraphenylethylene derivatives (S-TDs: TBN, TPN, and TPI) featuring different cationic groups, charge numbers, emission wavelengths, and hydrophobicities were successfully synthesized. Benefiting from distinct cell wall binding properties, S-TDs were collectively utilized to create a sensor array capable of imaging various microorganisms through their characteristic fluorescent signatures. Furthermore, the interaction mechanism between S-TDs and different microorganisms was explored by calculating the binding energy between S-TDs and cell membrane/wall constituents, including phospholipid bilayer and peptidoglycan. Using a combination of the fluorescence sensor array and a deep learning model of residual network (ResNet), readily differentiation of Gram-negative bacteria (G-), Gram-positive bacteria (G+), fungi, and their mixtures was achieved. Specifically, by extensive training of two ResNet models with large quantities of images data from 14 kinds of microorganism stained with S-TDs, identification of microorganism was achieved at high-level accuracy: over 92.8% for both Gram species and antibiotic-resistant species, with 90.35% accuracy for the detection of mixed microorganism in infected wound. This novel method provides a rapid and accurate method for microbial classification, potentially aiding in the diagnosis and treatment of infectious diseases.

Diagnosis of abdominal tuberculosis: Detection of mycobacterial CFP-10 and HspX proteins by gold nanoparticle-PCR amplified immunoassay

Attempts were made to improve the efficacy of PCR amplified immunoassay (I-PCR) for diagnosing abdominal TB cases by utilizing the gold nanoparticle (AuNP)-based I-PCR, where AuNPs were functionalized with detection antibodies/oligonucleotides that exhibited 84.3% sensitivity and 95.1% specificity. This assay would improve the ongoing algorithms used in abdominal TB diagnosis.

Progress in Procalcitonin Detection Based on Immunoassay

Procalcitonin (PCT) serves as a crucial biomarker utilized in diverse clinical contexts, including sepsis diagnosis and emergency departments. Its applications extend to identifying pathogens, assessing infection severity, guiding drug administration, and implementing theranostic strategies. However, current clinical deployed methods cannot meet the needs for accurate or real-time quantitative monitoring of PCT. This review aims to introduce these emerging PCT immunoassay technologies, focusing on analyzing their advantages in improving detection performances, such as easy operation and high precision. The fundamental principles and characteristics of state-of-the-art methods are first introduced, including chemiluminescence, immunofluorescence, latex-enhanced turbidity, enzyme-linked immunosorbent, colloidal gold immunochromatography, and radioimmunoassay. Then, improved methods using new materials and new technologies are briefly described, for instance, the combination with responsive nanomaterials, Raman spectroscopy, and digital microfluidics. Finally, the detection performance parameters of these methods and the clinical importance of PCT detection are also discussed.

Target-triggered dual signal amplification based on HCR-enhanced nanozyme activity for the sensitive visual detection of Escherichia coli

The detection of foodborne pathogens is crucial for food hygiene regulation and disease diagnosis. Colorimetry has become one of the main analytical methods in studying foodborne pathogens due to its advantages of visualization, low cost, simple operation, and no complex instrument. However, the low sensitivity limits its applications in early identification and on-site detection for trace analytes. In order to overcome such a limitation, herein we propose a joint strategy featuring dual signal amplification based on the hybridization chain reaction (HCR) and DNA-enhanced peroxidase-like activity of gold nanoparticles (AuNPs) for the sensitive visual detection of Escherichia coli. Target bacteria bound specifically to the aptamer domain in the capture hairpin probe, exposing the trigger domain for HCR and forming the extended double-stranded DNA (dsDNA) structures. The peroxidase-like catalytic capacity of AuNPs can be enhanced significantly by dsDNAs with the sticky ends of dsDNAs being adsorbed on AuNPs and the rigidity of dsDNAs causing the spatial regulation of AuNP concentration. The intensity of the enhancement was linearly related to the number of target bacteria. With the above strategy, the detection limit of our colorimetric method for Escherichia coli was down to 28 CFU mL-1 within a short analytical time (50 min). This study provides a new perspective for the sensitive and visual detection of early bacterial contamination in foods.

A portable microfluidic photometric detection method based on enzyme linked immunoscatter enhancement

Currently, the combination of smart phones and microfluidic chips is a commonly used device for point-of-care testing (POCT) detection. Enzyme linked immunosorbent assay (ELISA) is an effective way to detect specific proteins in disease. Because the detection accuracy of smartphone cameras is difficult to directly replace high-precision spectral devices, the combination of smartphones and ELISA has not been widely used. Therefore, this paper proposes a microfluidic photometric detection method based on ELISA scattering enhancement. Firstly, the scattering characteristics of IMB are mined, and the optimal value of absorbance error compensation parameter is obtained. Secondly, the absorbance error compensation model based on scattering enhancement characteristics is established to improve the image acquisition accuracy of smart phones. Finally, the microfluidic photometric detection chip is developed, and the optical path system, optical path adjustment system and POCT detection App of smart phone are designed. The optimal compensation parameters of IMB were obtained based on simulated samples, and the linearity of absorbance and concentration increased by 22.6% after compensation. In the IL-6 sample experiment, the detection results of the platform in this paper had a good linear correlation with IL-6 sample concentration, and the linear correlation coefficient was above 0.95459. At the same time, the detection limit and accuracy meet the detection requirements. Therefore, with the participation of smart phones and microfluidic chips, problems such as difficult carrying and complex operation in traditional ELISA daily detection have been solved, laying a foundation for the future promotion and application of ELISA based POCT platform.

Nanomaterials for detection of biomolecules and delivering therapeutic agents in theragnosis: A review

Nanomaterials are emerging facts used to deliver therapeutic agents in living systems. Nanotechnology is used as a compliment by implementing different kinds of nanotechnological applications such as nano-porous structures, functionalized nanomaterials, quantum dots, carbon nanomaterials, and polymeric nanostructures. The applications are in the initial stage, which led to achieving several diagnoses and therapy in clinical practice. This review conveys the importance of nanomaterials in post-genomic employment, which includes the design of immunosensors, immune assays, and drug delivery. In this view, genomics is a molecular tool containing large databases that are useful in choosing an apt molecular inhibitor such as drug, ligand and antibody target in the drug delivery process. This study identifies the expression of genes and proteins in analysis and classification of diseases. Experimentally, the study analyses the design of a disease model. In particular, drug delivery is a boon area to treat cancer. The identified drugs enter different phase trails (Trails I, II, and III). The genomic information conveys more essential entities to the phase I trials and helps to move further for other trails such as trails-II and III. In such cases, the biomarkers play a crucial role by monitoring the unique pathological process. Genetic engineering with recombinant DNA techniques can be employed to develop genetically engineered disease models. Delivering drugs in a specific area is one of the challenging issues achieved using nanoparticles. Therefore, genomics is considered as a vast molecular tool to identify drugs in personalized medicine for cancer therapy.

One-Step Purification of IgE Epitope-Specific Antibody Using Immunomagnetic Beads and Highly Sensitive Detection of Bovine β-Lactoglobulin for the Prediction of Milk Allergenicity in Foods

Bovine β-lactoglobulin (BLG) is a common allergen found in milk, and the immunoglobulin E (IgE) epitope plays a crucial role in cow milk allergy. Therefore, targeting the IgE epitope could be useful in accurately detecting BLG and assessing its allergenicity. However, producing an IgE epitope-specific antibody (IgE-EsAb) through traditional methods requires complex and time-consuming procedures. Here, IgE-EsAb was purified from rabbit anti-BLG sera by immunomagnetic beads in one step. Then, a sandwich ELISA (sELISA) based on the IgE-EsAb was developed to detect BLG and predict the potential milk allergenicity in foods. The obtained IgE-EsAb could specifically recognize the target IgE epitope of BLG and exhibited high affinity and specificity. The developed IgE-EsAb-based sELISA demonstrated an ultra-wide linear range of 3.9-1.28 × 105 ng/mL, with a limit of detection of 0.49 ng/mL for BLG. Additionally, the proposed immunoassay showed high specificity and recoveries (91.24-109.61%). The ability of the IgE-EsAb-based sELISA to evaluate the potential milk allergenicity in foods was validated using sera from cow milk allergy patients. These results suggest that immunomagnetic beads are an effective tool for rapidly obtaining the IgE-EsAb, and our proposed sELISA could be a reliable and user-friendly method for monitoring trace amounts of BLG and predicting the potential milk allergenicity of food samples.

Sensitive and highly rapid electrochemical measurement of airborne coronaviruses through condensation-based direct impaction onto carbon nanotube-coated porous paper working electrodes

Rapid detection of indoor airborne viruses is critical to prevent the spread of respiratory diseases. Herein, we present sensitive, highly rapid electrochemical measurement of airborne coronaviruses through condensation-based direct impaction onto antibody-immobilized, carbon nanotube-coated porous paper working electrodes (PWEs). Carboxylated carbon nanotubes are drop-cast on paper fibers to make three-dimensional (3D) porous PWEs. These PWEs have higher active surface area-to-volume ratios and electron transfer characteristics than conventional screen-printed electrodes. The limit of detection and detection time of the PWEs for liquid-borne coronaviruses OC43 are 65.7 plaque-forming units (PFU)/mL and 2 min, respectively. The PWEs showed sensitive and rapid detection of whole coronaviruses, which can be ascribed to the 3D porous electrode structure of the PWEs. Moreover, water molecules condense on airborne virus particles during air sampling, and these water-encapsulated virus particles (<4 µm) are impacted on the PWE for direct measurement without virus lysis and elution. The whole detection takes ∼10 min, including air sampling, at virus concentrations of 1.8 and 11.5 PFU/L of air, which can be due to the highly enriching and minimally damaging virus capture on a soft and porous PWE, demonstrating the potential for the rapid and low-cost airborne virus monitoring system.

Gold nanoparticle-decorated covalent organic frameworks as amplified light-scattering probes for highly sensitive immunodetection of Salmonella in milk

Traditional immunoassays exhibit insufficient screening sensitivity for foodborne pathogens due to their low colorimetric signal intensities. Herein, we propose an ultrasensitive dynamic light scattering (DLS) immunosensor for Salmonella based on a "cargo release-seed growth" strategy enabled by a probe, namely gold nanoparticle-decorated covalent organic frameworks (COF@AuNP). Large amounts of AuNPs in COF@AuNP can be released by acid treatment-induced decomposition of the imine-linked COF, and then they are enlarged via gold growth to generate a dramatically enhanced light-scattering signal, leading to a vast improvement in detection sensitivity. Based on an immunomagnetic microbead carrier, the proposed DLS immunosensor is capable of detecting trace Salmonella in milk in the range of 2.0 × 102-2.0 × 105 CFU mL-1, with a limit of detection of 60 CFU mL-1. The immunosensor also demonstrated excellent selectivity, good accuracy and precision, and high reliability for detecting Salmonella in milk.

SERS immuno- and apta-assays in biosensing/bio-detection: Performance comparison, clinical applications, challenges

Surface Enhanced Raman Spectroscopy is increasingly used as a sensitive bioanalytical tool for detection of variety of analytes ranging from viruses and bacteria to cancer biomarkers and toxins, etc. This comprehensive review describes principles of operation and compares the performance of immunoassays and aptamer assays with Surface Enhanced Raman scattering (SERS) detection to each other and to some other bioassay methods, including ELISA and fluorescence assays. Both immuno- and aptamer-based assays are categorized into assay on solid substrates, assays with magnetic nanoparticles and assays in laminar flow or/and strip assays. The best performing and recent examples of assays in each category are described in the text and illustrated in the figures. The average performance, particularly, limit of detection (LOD) for each of those methods reflected in 9 tables of the manuscript and average LODs are calculated and compared. We found out that, on average, there is some advantage in terms of LOD for SERS immunoassays (0.5 pM median LOD of 88 papers) vs SERS aptamer-based assays (1.7 pM median LOD of 51 papers). We also tabulated and analyzed the clinical performance of SERS immune and aptamer assays, where selectivity, specificity, and accuracy are reported, we summarized the best examples. We also reviewed challenges to SERS bioassay performance and real-life application, including non-specific protein binding, nanoparticle aggregation, limited nanotag stability, sometimes, relatively long time to results, etc. The proposed solutions to those challenges are also discussed in the review. Overall, this review may be interesting not only to bioanalytical chemist, but to medical and life science researchers who are interested in improvement of bioanalyte detection and diagnostics.

Nucleic acid aptamer-based biosensors and their application in thrombin analysis

Thrombin is a multifunctional serine protease that plays an important role in coagulation and anticoagulation processes. Aptamers have been widely applied in biosensors due to their high specificity, low cost and good biocompatibility. This review summarizes recent advances in thrombin quantification using aptamer-based biosensors. The primary focus is optical sensors and electrochemical sensors, along with their applications in thrombin analysis and disease diagnosis.

Hybridization chain reaction cascaded amplification platform for sensitive detection of pathogen

Rapid, sensitive, and accurate identification of pathogens is vital for preventing and controlling fish disease, reducing economic losses in aquaculture, and interrupting the spread of food-borne diseases in human populations. Herein, we proposed a hybridization chain reaction (HCR) cascaded dual-signal amplification platform for the ultrasensitive and specific detection of pathogenic microorganisms. A couple of specific primers for target bacterial 16S rRNAs were used to obtain amplified target single-stranded DNAs (AT-ssDNA). Then, AT-ssDNA initiated HCR amplification along with the opening of fluorophore (FAM) and a quencher (BHQ1) labeled hairpin reporter probe (H1), and the FAM fluorescence signal recovered. The proposed strategy could achieve a detection limit down to 0.31 CFU/mL for Staphylococcus aureus (S. aureus), 0.49 CFU/mL for Escherichia coli (E. coli) in buffer, and a linear range from 1 to 1 × 10⁶ CFU/mL for S. aureus, 1 to 1 × 10⁷ CFU/mL for E. coli. Furthermore, this platform enabled sensitive and precise detection of pathogenic microorganisms in complex samples such as fish blood and different organ tissues (large intestine, gallbladder, heart, liver, ren, gill, skin), which shows great potential in disease prevention and control in aquatic products.

Rapid nanocatalytic reaction using antibody-conjugated gold nanoparticles for simple and sensitive detection of parathyroid hormone

Biomolecule-conjugated metal nanoparticles (NPs) have been primarily used as colorimetric labels in affinity-based bioassays for point-of-care testing. A facile electrochemical detection scheme using a rapid nanocatalytic reaction of a metal NP label is required to achieve more quantitative and sensitive point-of-care testing. Moreover, all the involved components should be stable in their dried form and solution. This study developed a stable component set that allows for rapid and simple nanocatalytic reactions combined with electrochemical detection and applied it for the sensitive detection of parathyroid hormone (PTH). The component set consists of an indium-tin oxide (ITO) electrode, ferrocenemethanol (FcMeOH), antibody-conjugated Au NPs, and ammonia borane (AB). Despite being a strong reducing agent, AB is selected because it is stable in its dried form and solution. The slow direct reaction between FcMeOH⁺ and AB provides a low electrochemical background, and the rapid nanocatalytic reaction allows for a high electrochemical signal. Under optimal conditions, PTH could be quantified in a wide range of concentrations in artificial serum, with a detection limit of ~0.5 pg/mL. Clinical validation of the developed PTH immunosensor using real serum samples indicates that this novel electrochemical detection scheme is promising for quantitative and sensitive immunoassays for point-of-care testing.

Particulate Standard Establishment for Absolute Quantification of Nanoparticles by LA-ICP-MS

The development of nanotechnology has transformed many cutting-edge studies related to single-molecule analysis into nanoparticle (NP) detection with a single-NP sensitivity and ultrahigh resolution. While laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) has been successful in quantifying and tracking NPs, its quantitative calibration remains a major challenge due to the lack of suitable standards and the uncertain matrix effects. Herein, we frame a new approach to prepare quantitative standards via precise synthesis of NPs, nanoscale characterization, on-demand NP distribution, and deep learning-assisted NP counting. Gold NP standards were prepared to cover the mass range from sub-femtogram to picogram levels with sufficient accuracy and precision, thus establishing an unambiguous relationship between the sampled NP number in each ablation and the corresponding mass spectral signal. Our strategy facilitated for the first time the study of the factors affecting particulate sample capture and signal transductions in LA-ICP-MS analysis and culminated in the development of an LA-ICP-MS-based method for absolute NP quantification with single-NP sensitivity and single-cell quantification capability. The achievements would herald the emergence of new frontiers cut across a spectrum of toxicological and diagnostic issues related to NP quantification.

Metal-based nanomaterials and nanocomposites as promising frontier in cancer chemotherapy

Cancer is a disease associated with complex pathology and one of the most prevalent and leading reasons for mortality in the world. Current chemotherapy has challenges with cytotoxicity, selectivity, multidrug resistance, and the formation of stemlike cells. Nanomaterials (NMs) have unique properties that make them useful for various diagnostic and therapeutic purposes in cancer research. NMs can be engineered to target cancer cells for early detection and can deliver drugs directly to cancer cells, reducing side effects and improving treatment efficacy. Several of NMs can also be used for photothermal therapy to destroy cancer cells or enhance immune response to cancer by delivering immune-stimulating molecules to immune cells or modulating the tumor microenvironment. NMs are being modified to overcome issues, such as toxicity, lack of selectivity, increase drug capacity, and bioavailability, for a wide spectrum of cancer therapies. To improve targeted drug delivery using nano-carriers, noteworthy research is required. Several metal-based NMs have been studied with the expectation of finding a cure for cancer treatment. In this review, the current development and the potential of plant and metal-based NMs with their effects on size and shape have been discussed along with their more effective usage in cancer diagnosis and treatment.

Effect of Selenium Nanoparticle Size on IL-6 Detection Sensitivity in a Lateral Flow Device

Sepsis is the body's response to an infection. Existing diagnostic testing equipment is not available in primary care settings and requires long waiting times. Lateral flow devices (LFDs) could be employed in point-of-care (POC) settings for sepsis detection; however, they currently lack the required sensitivity. Herein, LFDs are constructed using 150-310 nm sized selenium nanoparticles (SeNPs) and are compared to commercial 40 nm gold nanoparticles (AuNPs) for the detection of the sepsis biomarker interleukin-6 (IL-6). Both 310 and 150 nm SeNPs reported a lower limit of detection (LOD) than 40 nm AuNPs (0.1 ng/mL compared to 1 ng/mL), although at the cost of test line visual intensity. This is to our knowledge the first use of larger SeNPs (>100 nm) in LFDs and the first comparison of the effect of the size of SeNPs on assay sensitivity in this context. The results herein demonstrate that large SeNPs are viable alternatives to existing commercial labels, with the potential for higher sensitivity than standard 40 nm AuNPs.