Simple Detection Research Articles

Photocatalytic colorimetry and fluorescence dual-signal biosensor for instant determination of terminal deoxynucleotidyl transferase

Terminal deoxynucleotidyl transferase (TdT) is a crucial biomarker for diseases such as lymphoblastic leukemia. Herein, a photocatalytic colorimetry and fluorescence dual-signal biosensor (PhoCoF-sensor) for simple, low-cost and sensitive detection of TdT was developed, which integrated with the TdT-triggered polymerization reaction and the fluorescence-photocatalytic dual performance of double-strand DNA/SYBR Green-I (dsDNA/SG-I) complex. The target TdT catalyzed the elongation of single-stranded DNA in the dTTP substrate pool, and then hybridized with complementary DNA to form dsDNA/SG-I complex that exhibited obvious fluorescent and excellent photocatalytic activity. Reactive oxygen species were generated from photosensitization of the dsDNA/SG-I complex acted as the visual colorimetric readout. The PhoCoF-sensor was successfully used to detect TdT activity with a series of color and fluorescence changes in the concentration range from 0.5 U/mL to 20.0 U/mL. The PhoCoF-sensor further improves the assay simplicity and accuracy and reduces the time and cost, which overcomes the limitations of traditional detection TdT methods and single-signal sensors. Additionally, this PhoCoF-sensor can readily be integrated with centrifugal microfluidic device for one-step test and achieve quantitative determination without sophisticated instruments. Moreover, the PhoCoF-sensor has good sensitivity and good practical reliability and is suitable for instant determination in early disease diagnosis and drug discovery.

Recognition mechanism of split T-2 toxin aptamer coupled with reliable dual-mode detection in peanut and beer

T-2 toxin is a highly poisonous trichothecene and a well-known contaminant in cereal grains and cereal-based products, hence it is essential to design a simple, reliable, and precise detection mechanism for ensuring food safety and human health. In response to this imperative, we innovatively designed an unreported split T-2 toxin aptamer probe, and the cooperative binding mechanism of the split aptamer to T-2 was first investigated. Based on these, a dual-mode fluorescence (FL) and fluorescence polarization (FP) aptasensor was developed for T-2 toxin detection in peanut and beer samples. The results showed an excellent detection property of the aptasensor, indicating a linear range of 0.1–20 nM and 0.2–50 nM at a detection limit of 0.1 nM, 0.12 nM for FL and FP signals, respectively. In actual sample assays, recoveries of 101.7%–115.2%, 109.8%–121.6% for FL and FP mode, respectively, were reached in peanuts, whereas recoveries ranged from 81.0% -124.0%, 94.1%–107.8% for FL and FP mode in beer. This designed dual-mode biosensor not only showed excellent performances but also verified each other and proved the reliability of binary split aptamer molecular probes.

Research progress on the detection of foodborne pathogens based on aptamer recognition.

Foodborne diseases caused by bacterial contamination are a serious threat to food safety and human health. The classical plate culture method has the problems of long detection cycle, low sensitivity and specificity, and complicated operation, which cannot meet the growing demand for rapid quantitative detection of pathogenic bacteria. The frequent outbreak of foodborne diseases has put forward higher requirements for rapid and simple detection technology of foodborne pathogens. Aptamer is a kind of oligonucleotide fragment that can recognize targets with the advantages of high affinity and good specificity. The target can be range from proteins, small molecules, cells bacteria, and even viruses. Herein, the latest advances in sensitive and rapid detection of foodborne pathogens based on aptamer recognition was reviewed. Special attention has been paid to the obtained sequences of aptamers to various foodborne pathogens, the optimization of sequences, and the mechanism of aptamer recognition. Then, the research progress of biosensors for the detection of pathogenic bacteria based on aptamer recognition were summarized. Some challenges and prospects for the detection of foodborne pathogens based on aptamer recognition were prospected. In summary, with the further deepening of aptamer research and improvement of detection technology, aptamer-based recognition can meet the needs of rapid, sensitive, and accurate detection in practical applications.

Development and Validation of a Simple High-Pressure Liquid Chromatography-Ultraviolet Detection Method for Simultaneous Quantitation of First-Line Anti-Tuberculosis Drugs in Formulations of Fixed-Dose Combination.

The current treatment protocol for drug-sensitive tuberculosis involves all four first-line anti-tuberculosis drugs: rifampicin, isoniazid, pyrazinamide and ethambutol hydrochloride in a single tablet, known as fixed-dose combination tablets. However, the analytical methods are scanty to test all these drugs simultaneously in a single run without any pre-sample process or using a simple method suitable for resource-limited settings. In this method, 50mM potassium phosphate buffer containing 0.2% triethylamine (without pH adjustment) added with acetonitrile (98:2, v/v) was served as mobile phase A, while mobile phase B was 100% acetonitrile. All four drugs were separated within 10.3min using a gradient mobile phase program in a C18 column (150mm × 4.6mm; 5μm) and detected at two ultraviolet wavelengths (238nm for rifampicin, isoniazid and pyrazinamide, and 210nm for ethambutol hydrochloride). The method was selective, sensitive and linear with a correlation coefficient >0.999 with the acceptable precision and accuracy (<2% relative standard deviation) for all four drugs. In conclusion, the method is simple and it does not require any pH adjustment of the buffer/mobile phase, and within 11min, the separation of all four drugs can be achieved. Overall, the method is suitable for quality testing of fixed-dose combination tablets in limited-resource settings.

A new green approach to L-histidine and β-alanine analysis in dietary supplements using rapid and simple contactless conductivity detection integrated with high-resolution glass-microchip electrophoresis.

The analysis of dietary supplements is far less regulated than pharmaceuticals, leading to potential quality issues. Considering their positive effect, many athletes consume supplements containing L-histidine and β-alanine. A new microfluidic method for the determination of L-histidine and β-alanine in dietary supplement formulations has been developed. For the first time, capacitively coupled contactless conductivity detection was employed for the microchip electrophoresis of amino acids in real samples. A linear relationship between detector response and concentration was observed in the range of 10-100µmol L-1 for L-histidine (R2 = 0.9968) and β-alanine (R2 = 0.9954), while achieved limits of detection (3 × S/N ratio) were 4.2µmol L-1 and 5.2µmol L-1, respectively. The accuracy of the method was confirmed using recovery experiments as well as CE-UV-VIS and HPLC-UV-VIS techniques. The developed method allows unambiguous identification of amino acids in native form without chemical derivatization and with the possibility of simultaneous analysis of amino acids with metal cations.

Development of real-time recombinase polymerase amplification (RPA) and RPA combined with lateral flow dipstick (LFD) assays for the rapid and sensitive detection of cyprinid herpesvirus 3.

In this issue, we established rapid, cost-effective, and simple detection methods including recombines polymerase amplification with lateral flow dipstick (RPA-LFD) and real-time RPA for cyprinid herpesvirus 3(CyHV-3), and evaluated their sensitivity, specificity, and applicability, the real-time RPA method could achieve sensitive diagnosis of CyHV-3 within 1.3 copies per reaction, respectively. The real-time RPA method is 10-fold more sensitive than RPA-LFD method. The exact number of CyHV-3 can be calculated in each sample by real-time RPA. The sera from koi also can be tested in these methods. In addition, no cross-reaction was observed with other related pathogens, including carp oedema virus (CEV), spring viraemia of carp virus (SVCV), cyprinid herpesvirus 1(CyHV-1), cyprinid herpesvirus 2(CyHV-2), type I grass carp reovirus (GCRV-I), type II GCRV (GCRV-II), type III GCRV (GCRV-III), and Aeromonas hydrophila.

A Foldable Thermoplastic Microdevice Integrating Isothermal Amplification and Schiff-Reaction-Based Colorimetric Assay for the Detection of Infectious Pathogens

In this study, we introduce a plastic-based foldable microdevice that integrates loop-mediated isothermal amplification (LAMP) and a colorimetric assay based on the Schiff reaction to detect the genes of infectious bacteria. The device comprises two sides: a sample zone containing amplification chambers and a detection zone for the colorimetric assay. The detection zone contains poly(methyl methacrylate) structures for transferring the colorimetric reagent-soaked glass micro-fiber paper into the sample chambers. Specific genes of Staphylococcus aureus (S. aureus) and Streptococcus pneumoniae (S. pneumoniae), the most common bacterial infection causes, were amplified by LAMP assay. The S. aureus gene was detected up to 10 fg/μL and the S. pneumoniae gene up to 0.1 pg/μL. The amplified target genes were visually identified using a colorimetric assay with Schiff’s reagent, which showed clear color discrimination through a reaction with aldehyde groups derived from the DNA in the amplicons. The introduced method, integrating amplification and detection processes in a single device, is expected to be utilized in point-of-care testing analysis for the simple and rapid detection of infectious pathogens.

Portable and Flexible Hydrogel Sensor for On-Site Atrazine Assay on Agricultural Products.

There is growing attention focused toward the problems of ecological sustainability and food safety raised from the abuse of herbicides, which underscores the need for the development of a portable and reliable sensor for simple, rapid, and user-friendly on-site analysis of herbicide residues. Herein, a novel multifunctional hydrogel composite is explored to serve as a portable and flexible sensor for the facile and efficient analysis of atrazine (ATZ) residues. The hydrogel electrode is fabricated by doping graphite-phase carbon nitride (g-C3N4) into the aramid nanofiber reinforced poly(vinyl alcohol) hydrogel via a simple solution-casting procedure. Benefiting from the excellent electroactivity and large specific surface area of the solid nanoscale component, the prepared hydrogel sensor is capable of simple, rapid, and sensitive detection of ATZ with a detection limit down to 0.002 ng/mL and per test time less than 1 min. After combination with a smartphone-controlled portable electrochemical analyzer, the flexible sensor exhibited satisfactory analytical performance for the ATZ assay. We further demonstrated the applications of the sensor in the evaluation of the ATZ residues in real water and soil samples as well as the user-friendly on-site point-of-need detection of ATZ residues on various agricultural products. We envision that this flexible and portable sensor will open a new avenue on the development of next-generation analytical tools for herbicide monitoring in the environment and agricultural products.

A Fluorescent Probe for Hydrazine Based on 4-hydroxycoumarin with High Selectivity and Sensitivity

Background: Therefore, the development of reliable analytical techniques with high selectivity and sensitivity to detect hydrazine is required for the protection of human health and safety. Objectives: Traditional methods for detecting N2H4 are frequently time-consuming, less accurate, and unsuitable for the analysis of living systems. Numerous fluorescent probes for hydrazine have been produced and gained some valuable results recently. The creation of a simple fluorescent probe for hydrazine detection is the goal of this project Method: In this study, 300 µL of probe 3-methyl-2-oxo-2H-chromen-7-yl propionate (MOCP) was mixed with an equivalent amount of the solution of each analyte to obtain the measurement solution. Following a 10-minute room temperature incubation period, the fluorescence spectra of the resultant solution were recorded. Results: The fluorescence intensity of the probe was noticeably enhanced when N2H4 was added to the probe, but almost no fluorescence enhancement was observed when other competitive ions were added. Conclusion: A hydrazine fluorescent probe based on 4-hydroxycoumarin fluorophore was developed. The probe MOCP displayed high sensitivity and selectivity for hydrazine, with a color change from colourless to blue for detection by the naked eye. Moreover, it demonstrated a low detection limit of 20 nM and a fast reaction time of 30 s.

A Non‐Enzymatic Electrochemical Sensor Based on Cerium Oxide Nanocubes for the Rapid Detection of Hydrogen Peroxide Residues in Food Samples†

The rapid and simple detection methods of hydrogen peroxide (H2O2) residues is highly required for food safety. Herein, an electrochemical H2O2 sensor is developed with cerium oxide nanocubes as highly active non‐enzymatic catalyst. Combined with carbon black to improve conductivity, the disposable sensor can determine H2O2 in the range from 100 to 100 μM with a limit of detection (LOD) of 100 nM. This sensor also shows good selectivity and reproducibility, which is enabled to detect H2O2 in real food samples without any pretreatment in 100 s, providing a new solution for the direct quantitative measurement of H2O2 residues for food safety. © 2024 Institute of Electrical Engineer of Japan and Wiley Periodicals LLC.

Vis-NIR spectroscopic discriminant analysis of aflatoxin B1 excessive standard in peanut meal as feedstuff materials

A fast, simple and reagent-free detection method for aflatoxin B1 (AFB1) is of great significance to food safety and human health. Visible and near-infrared (Vis-NIR) spectroscopy was applied to the discriminant analysis of AFB1 excessive standard of peanut meal as feedstuff materials. Two types of excessive standard discriminant models based on spectral quantitative analysis with partial least squares (PLS) and direct pattern recognition with partial least squares-discrimination analysis (PLS-DA) were established, respectively. Multi-parameter optimization of Norris derivative filtering (NDF) was used for spectral preprocessing; the two-stage wavelength screening method based on equidistant combination-wavelength step-by-step phase-out (EC-WSP) was used for wavelength optimization. A rigorous sample experimental design of calibration-prediction-validation was utilized. The calibration and prediction samples were used for modeling and parameter optimization, and the selected model was validated using the independent validation samples. For quantitative analysis-based, the positive, negative and total recognition-accuracy rates in validation (RARV+, RARV-, and RARV) were 84.8 %, 74.6 % and 79.8 %, respectively; but, the relative root mean square error of prediction was as high as 51.0 %. For pattern recognition-based, the RARV+, RARV-, and RARV were 93.3 %, 90.5 % and 91.9 %, respectively. Moreover, the number of wavelengths N was drastically reduced to 17, and the discrete wavelength combination was in NIR overtone frequency region. The results indicated that, the EC-WSP-PLS-DA model achieved significantly better discrimination effect. Thus demonstrated that Vis-NIR spectroscopy has feasibility for the excessive standard discrimination of aflatoxin B1 in feedstuff materials.

Shadow Detection in Remote Sensing Images Based on Spectral Radiance Separability Enhancement.

Shadow detection is a basic task of remote sensing image analysis, but it is often seriously disturbed by vegetation, water bodies, and black objects. It is observed that vegetation and dark objects often show a dark look in visible bands but brighter in the near-infrared (NIR), and is also noticed that the reflection of inland water bodies in the green band is stronger than that in the blue band. Taking advantage of these physical properties and combining them with the bluish and dark appearance of shadows, we propose a simple but effective shadow detection method for multispectral remote sensing images. These physical properties are used to create transformation models that suppress features such as vegetation, water bodies, etc., but at the same time enhance shadows. Then, we transform the shadow representation into a color space to generate candidate shadows using dominant color components. To separate shadows from the others, we propose two indexes, the normalized Color Difference Composite Index (CDCI) and Color Purity Index (CPI), and fuse them to achieve shadows and their confidence. The experimental results indicate that the proposed method can effectively detect the shadows in multispectral images and outperforms the state-of-the-art approaches.

Manipulation of magnetic beads for actively capturing Vibrio parahaemolyticus and nucleic acid based on microfluidic system.

Rapid biological detection of pathogen micro-organisms has attracted much attention for practical biomedical applications. Despite the development in this field, it is still challenging to achieve simple and rapid biological detection using the microfluidic method. Herein, we propose a novel strategy of biological detection that combines precise detection control of the capillary microfluidic chip and versatile manipulation of magnetic beads. The microfluidic chip was fabricated via laser cutting, which utilized capillary pressure to realize rapid passive injection of liquid samples. Under an external magnetic field, the aptamer-modified magnetic beads were actuated to mix with Vibrio parahaemolyticus (V. parahaemolyticus) and its nucleic acid in the capillary microfluidic chip for rapid selective capture and detection, which could be achieved within 40 min. The experimental results demonstrated that V. parahaemolyticus could be captured using on-chip immunomagnetic beads with a high efficiency and significantly enhanced detection value. Due to these superior performances, the capillary microfluidic system, based on the manipulation of magnetic beads, demonstrated great potential for automatic biological detection.

Electrochemical Detection of Benzenediols using Carbon-Supported Catalysts

A novel implementation of an electrochemical sensors making use of Screen-Printed Electrodes (SPE) has been discussed. SPE's modified with Carbon-supported Platinum (Pt/C) and Gold (Au/C) were used to detect the three benzenediol isomers, Catechol (CC), Hydroquinone (HQ) and Resorcinol (RS) in acidic media using traditional electrochemical analytical methods such as Cyclic Voltammetry (CV), Chronoamperometry (CA) and Differential Pulse Voltammetry (DPV). Detection of each benzenediol in isolation was possible by CV measurements, and peak oxidation potentials for each isomer were noted. Simultaneous detection of more than one, or all analytes in the same solution was also observed through DPV, once again noting the peak oxidation potentials. Quantification limits were observed using CA's across concentration values ranging from close to saturation down to 1 mM for CC and HQ, and 100 nM for RS, until the recorded current values were nearly indistinguishable to a blank 1 M HCl solution containing no analyte(s), and also evaluating the maximum possible linear range of sensing. The analytes were introduced to the sensor elements in controlled amounts and the electrochemical responses of the sensor elements were recorded and processed. Measurements were repeated across two potentiostats to ensure reproducibility. With these results, successful detection of benzenediols in acidic environment was possible using modified SPE's, proving a potential viable mechanism for quick, simple and inexpensive Volatile Toxic Organic Compounds (VTOC) detection and monitoring.

A turn-on fluorescent probe based on pyrene for hydrazine detection

This paper presents a novel fluorescent probe (GNEM) based on a pyrene fluorophore, with dicarboximide as the recognition unit for hydrazine. The fluorescence probe can be synthesized in a simple one-step process. A highly selective and sensitive fluorescence turn-on GNEM synthesized. GNEM react with hydrazine through nucleophilic addition, leading to the deprotection of dicarboximide and the release of dicarboximide hydrazine, resulting in significant blue fluorescence. This enhanced emission is attributed to the intramolecular charge transfer (ICT) sensing mechanism of GNEM. In addition, detection of hydrazine in soil and water is conducted. By designing a simple detection device, the hydrazine content in the air can be quantitatively measured.

Sucrose-Powered Liposome Nanosensors for Urinary Glucometer-Based Monitoring of Cancer.

Timely detection of early-stage cancer holds immense potential in enhancing prognostic outcomes. There is an increasing desire for versatile tools to enable simple, sensitive, and cost-effective cancer detection. By exploiting the extraintestinal metabolic inertness and efficiency renal clearance of sucrose, we designed a liposome nanosensor using sucrose as a messenger to convert tumor-specific esterase activity into glucose meter readout, enabling economical and sensitive uri-nalysis for cancer detection in point-of-care testing (POCT). Our results demonstrate that the nanosensors exhibited sig-nificant signal differences between tumor-bearing and healthy mice in both orthotopic and metastatic tumor models. Ad-ditionally, efficient elimination of the nanosensors through the hepatobiliary pathway was observed with no significant toxicity. Such a non-invasive diagnostic modality significantly assists in personalized pharmacological treatment and fol-low-up efficacy assessment. We envision that this modular liposome nanosensor platform might be applied for economi-cally detecting diverse diseases via a simple urinary test.

α-Synuclein: A Promising Biomarker for Parkinson's Disease and Related Disorders.

Mutations in the SNCA gene, which encodes α-synuclein (α-syn), play a key role in the development of genetic Parkinson's disease (PD). α-Syn is a major component of Lewy bodies in PD and glial cytoplasmic inclusions in multiple system atrophy (MSA). Rapid eye movement sleep behavior disorder patients often progress to PD, dementia with Lewy bodies, or MSA, which are collectively known as α-synucleinopathies. The loss of dopaminergic neurons with Lewy bodies precedes motor dysfunction in these diseases, but the mechanisms of neurodegeneration due to α-syn aggregation are poorly understood. Monitoring α-syn aggregation in vivo could serve as a diagnostic biomarker and help elucidate pathogenesis, necessitating a simple and accurate detection method. Seed amplification assays (SAAs), such as real-time quaking-induced conversion and protein misfolding cyclic amplification, are used to detect small amounts of abnormally structured α-syn protofibrils, which are central to aggregation. These methods are promising for the early diagnosis of α-synucleinopathy. Differences in α-syn filament structures between α-synucleinopathies, as observed through transmission electron microscopy and cryo-electron microscopy, suggest their role in the pathogenesis of neurodegeneration. SAAs may differentiate between subtypes of α-synucleinopathy and other diseases. Efforts are also being made to identify α-syn from blood using various methods. This review introduces body fluid α-syn biomarkers based on pathogenic α-syn seeds, which are expected to redefine α-synucleinopathy diagnosis and staging, improving clinical research accuracy and facilitating biomarker development.

Silver-doped microcrystalline cellulose as a material for simple detection of urinary cysteine using a smartphone

Silver-doped microcrystalline cellulose as a material for simple detection of urinary cysteine using a smartphone

Designing a Simple Electrochemical Genosensor for the Detection of Urinary PCA3, a Prostate Cancer Biomarker

This study investigates the feasibility of a simple electrochemical detection of Prostate Cancer Antigen 3 (PCA3) fragments extracted from patients’ urine, using a thiolated single-strand DNA probe immobilized on a gold surface without using a redox probe. To enhance the PCA3 recognition process, we conducted a comparative analysis of the hybridization location using two thiolated DNA probes: Probe 1 targets the first 40 bases, while Probe 2 targets the fragment from bases 47 to 86. Hybridization with PCA3 followed, using square wave voltammetry. The limit of detection of the designed genosenors were of the order of (2.2 ng/mL), and (1.6 ng/mL) for Probes 1 and 2, respectively, and the subsequent sensitivities were of the order of (0.09 ± 0.01) µA−1 · µg−1 · mL and (0.10 ± 0.01) µA−1 · µg−1 · mL. Specificity tests were then conducted with the sensor functionalized with Probe 2, as it presents better analytical performances. The electrochemical results indicate that the designed sensor can clearly discriminate a complementary target from a non-complementary one. A further modeling of the calibration curves with the Power Law/Hill model indicates that the dissociation constant increases by one order of magnitude, confirming the ability of the designed sensor to perfectly discriminate complementary targets from non-complementary ones.

Quartz Crystal Microbalance as a Holistic Detector for Quantifying Complex Organic Matrices during Liquid Chromatography: 1. Coupling, Characterization, and Validation.

A matrix in highly complex samples can cause adverse effects on the trace analysis of targeted organic compounds. A suitable separation of the target analyte(s) and matrix before the instrumental analysis is often a vital step for which chromatographic cleanup methods remain one of the most frequently used strategies, particularly high-performance liquid chromatography (HPLC). The lack of a simple real-time detection technique that can quantify the entirety of the matrix during this step, especially with gradient solvents, renders optimization of the cleanup challenging. This paper, along with a companion one, explores the possibilities and limitations of quartz crystal microbalance (QCM) dry-mass sensing for quantifying complex organic matrices during gradient HPLC. To this end, this work coupled a QCM and a microfluidic spray dryer with a commercial HPLC system using a flow splitter and developed a calibration and data processing strategy. The system was characterized in terms of detection and quantification limits, with LOD = 4.3-15 mg/L and LOQ = 16-52 mg/L, respectively, for different eluent compositions. Validation of natural organic matter in an environmental sample against offline total organic carbon analysis confirmed the approach's feasibility, with an absolute recovery of 103 ± 10%. Our findings suggest that QCM dry-mass sensing could serve as a valuable tool for analysts routinely employing HPLC cleanup methods, offering potential benefits across various analytical fields.