Enhanced Detection Sensitivity Research Articles

Applications of metals and metal compounds in improving the sensitivity of microfluidic biosensors - a review.

The enhancement of detection sensitivity in microfluidic sensors has been a continuously explored field. Initially, many strategies for sensitivity improvement involved introducing enzyme cascade reactions, but enzyme-based reactions posed challenges in terms of cost, stability, and storage. Therefore, there is an urgent need to explore enzyme-free cascade amplification methods, which are crucial for expanding the application range and improving detection stability. Metal or metal compound nanomaterials have gained great attention in the exploitation of microfluidic sensors due to their ease of preparation, storage, and lower cost. The unique physical properties of metallic nanomaterials, including surface plasmon resonance, surface-enhanced Raman scattering, metal-enhanced fluorescence, and surface-enhanced infrared absorption, contribute significantly to enhancing detection capabilities. The metal-based catalytic nanomaterials, exemplified by Fe3O4 nanoparticles and metal-organic frameworks, are considered viable alternatives to biological enzymes due to their excellent performance. Herein, we provide a detailed overview of the applications of metals and metal compounds in improving the sensitivity of microfluidic biosensors. This review not only highlights the current developments but also critically analyzes the challenges encountered in this field. Furthermore, it outlines potential directions for future research, contributing to the ongoing development of microfluidic biosensors with improved detection sensitivity.

Passive Wireless Partial Discharge Sensors with Multiple Resonances.

Partial discharge (PD) is the dominant insulating defect in Gas-Insulated Switchgear (GIS). The existing detection methods are mainly divided into built-in wire-connected disk antennas with destructive drilling and external ultra-high frequency antennas with poor anti-interference ability. This research introduces a passive wireless PD sensor implanted inside GIS on the observation window. The sensor is implemented by a sheeting branch-inductor with multiple resonances which is able to enhance detection sensitivity. A coaxially aligned readout circuit, positioned outside the GIS, interrogates the PD sensor to wirelessly obtain the PD signal. The proposed sensing scheme improves signal-to-noise ratio and ensures minimal disruption to the electric field distribution inside GIS. An experimental setup was established in a controlled laboratory environment to benchmark the multi-resonant sensor against the commercial UHF sensor. A 2.5-times enhancement of signal strength was observed. Since our sensor was implanted inside the GIS, a high signal-to-noise ratio (68.82 dB) was obtained. Moreover, we constructed a wireless calibration test to investigate the accuracy of the proposed sensor. The precision of the signal test was as high as 0.72 pC. The pulse phase distribution information was collected to demonstrate a phase-resolved partial discharge (PRPD) pattern. The experiment results validate the effectiveness of the proposed method and demonstrate excellent performance in PD detection.

Phosphorylation-amplified synchronized droplet microfluidics sensitizes bacterial growth kinetic real-time monitoring

The necessity for rapid and accurate bacterial growth monitoring is imperative across various domains, including healthcare and environmental safety. We introduce the self-synchronized droplet-amplified electrical screening cytometry (SYNC) system, a novel meld of droplet microfluidics and electrochemical amplification tailored for precise bacterial growth kinetic monitoring. SYNC encapsulates single bacteria in picolitre droplets, enabling real-time, fluorescence-free electrochemical monitoring. A specially devised phosphorylation-amplified culture medium translates bacterial metabolic activity into discernible electrical impedance changes. The dual-channel design and a rail-based structure in SYNC facilitate parallel screening and self-synchronization of droplets, addressing the limitations of conventional impedance cytometry. SYNC showcases a 5-fold enhancement in detection sensitivity and reduces 50% of the detection time compared to traditional approaches. Notably, SYNC is pioneering in providing exact initial bacterial concentrations, achieve to 104 bacteria/ml, a capability unmatched by existing real-time techniques measuring electrochemical variations. Along with its robust performance, this earmarks SYNC as a powerful tool for applications such as antibiotic susceptibility testing, food quality monitoring, and real-time water bacteria monitoring, paving the way for enhanced microbial process management and infection control.

Ultrasensitive Detection of Tumor Suppressor Gene Methylation by Piezoelectric Sensing Based on Enrichment of Transcription Activator-Like Effectors.

The detection of DNA methylation at cytosine/guanine dinucleotide (CpG) islands in promoter regions of tumor suppressor genes has great potential for early cancer screening, diagnosis, and prognosis monitoring. Nevertheless, achieving accurate, sensitive, cost-effective, and quantitative detection of target methylated DNA remains challenging. Herein, we propose a novel piezoelectric sensor (series piezoelectric quartz crystal (SPQC)) based on transcription activator-like effectors (TALEs) for detecting DNA methylation of Ras association domain family 1 isoform A (RASSF1A) tumor suppressor genes (R-5mC). The sensor employs TALEs-Ni magnetic beads to specifically recognize and separate the R-5mC, thereby improving the detection selectivity. The TALEs-Ni magnetic beads-R-5mC complex is sheared by a nucleic acid enzyme (DNAzyme) to release the single-stranded DNA (ST). ST initiates a catalyzed hairpin assembly (CHA) reaction on the surface of the electrode, which in turn triggers the hybridization chain reaction (HCR) and silver staining for enhanced detection sensitivity. The strategy exhibits a linear response in the detection of R-5mC in the range of 1 fM to 1 nM with a detection limit of 0.79 fM. R-5mC as low as 0.01% can be detected, even in the presence of large numbers of unmethylated DNA. The detection of R-5mC in circulating cell-free DNA (cfDNA) derived from clinical plasma specimens of lung cancer patients yielded satisfactory results.

Special RCA based sensitive point‐of‐care detection of HPV mRNA for cervical cancer screening

AbstractDeveloping the sensitive point‐of‐care testing (POCT) of oncogenic nucleic acids from human papillomavirus (HPV) infection is essential in preventing cervical cancer, especially in resource‐limited settings. Rolling circle amplification (RCA) is attractive in achieving POCT via nucleic acid‐based aggregation under isothermal conditions. However, the influence of RCA product structure on the aggregation remains unexplored resulting in limited sensitivity. Here, a minimum secondary structured RCA technique (MSS‐RCA) is developed by designing a unique circular template, demonstrating significantly enhanced detection sensitivity with only one amplification step and one primer under isothermal conditions. The amplification efficiency of MSS‐RCA could be kinetically manipulated by controlling the secondary structure of the circular template. Introducing the invertase probe to MSS‐RCA, HPV16 E6/E7 nucleic acid target was detected with a personal glucose meter (PGM) with a sensitivity of 5 fm (50 zmol in 10 µL). This integrated MSS‐RCA‐PGM detection system was successfully applied to detect HPV16 E6/E7 mRNA extracted from 54 cervical swab samples reaching a positive predictive value of 100.00% and negative predictive values of 96.00% (77.77% to 99.40%, 95% CI). MSS‐RCA‐PGM provides a sensitive POCT platform for the detection of nucleic acid biomarkers for screening of cervical cancer or other diseases.

Sensitive and visual detection of SARS-CoV-2 using RPA-Cas12a one-step assay with ssDNA-modified crRNA

BackgroundCRISPR-Cas12a based one-step assays are widely used for nucleic acid detection, particularly for pathogen detection. However, the detection capability of the one-step assay is reduced because the Cas12a protein competes with the isothermal amplification enzymes for the target DNA and cleaves it. Therefore, the key to improving the sensitivity of the one-step assay is to address the imbalance between isothermal amplification and CRISPR detection. In previous study, we developed a Cas12a one-step assay using single-stranded DNA (ssDNA)-modified crRNA (mD-crRNA) and applied this method for the detection of pathogenic DNA. ResultsHere, we utilized mD-crRNA to establish a sensitive one-step assay that enables the visual detection of SARS-CoV-2 under ultraviolet light, achieving a detection limit of 5 aM without cross-reactivity. The sensitivity of mD-crRNA in the one-step assay was 100-fold higher than that of wild-type crRNA. Mechanistic studies revealed that the addition of ssDNA at the 3′ end of mD-crRNA attenuates the binding affinity between the Cas12a-mD-crRNA complex and the target DNA. Consequently, this reduction in binding affinity decreases the cis-cleavage activity of Cas12a, mitigating its cleavage of the target DNA in the one-step assay. As a result, there is an augmentation in the amplification and accumulation of target DNA, thereby enhancing detection sensitivity. In the clinical testing of 40 SARS-CoV-2 RNA samples, the concordance between the results of the one-step assay and known qPCR results was 97.5 %. SignificanceThe one-step assay using mD-crRNA proves to be highly sensitive and specificity and visually effective for the detection of SARS-CoV-2. Our study delves into the application of the mD-crRNA-mediated one-step assay in nucleic acid detection and its associated reaction mechanism. This holds great significance in addressing the inherent incompatibility issues between isothermal amplification and CRISPR detection.

A simple and green offline-online capillary electrophoresis stacking strategy for the simultaneous determination of hydrophobic compounds in complicated samples using sodium dodecyl sulfate as the solubilizer and pseudophase

BackgroundCapillary electrophoresis is a powerful analytical method featured with high separation efficiency, minimal sample requirements, and reduced organic solvents consumption. However, its low sensitivity hinders its wide application in determination of trace analytes especially for the weakly ionized hydrophobic compounds. Offline and Online capillary electrophoresis stacking methods are more favored to enhance detection sensitivity of analytes. The determination of two sesquiterpenes and an alkaloid from the dried root of Lindera aggregata merged as an example for developing a simple, sensitive and green method for the simultaneous determination of two hydrophobic compounds in complicated matrix samples. ResultsAn offline-online capillary electrophoresis stacking strategy by integrating micro matrix solid phase dispersion with field-amplified sample stacking and micelle to cyclodextrin stacking has been developed for the simultaneous determination of dehydrocostus lactone, linderane, norisoboldine in complex matrices. The optimized parameters were set at 65 mM sodium dihydrogen phosphate, 35% methanol, 180 s for sample injection and 210 s for cyclodextrin injection, 20 mM sodium dodecyl sulfate of sample matrix for online stacking; 1:1 sample to MCM-48, 180 s grinding time, and 1,000 μL of 20 mM sodium dodecyl sulfate elution for offline procedure. Under the optimum conditions, the method showed good linearity with correlation coefficients (R2≥0.9927), low limits of detection within the range of 25-50 ng mL-1, satisfactory repeatability and reproducibility below 3.98%, and acceptable recoveries between 94% and 97%. The developed method was successfully applied to two real samples, the root of L. aggregata and rat feces. SignificanceSodium dodecyl sulfate is firstly used as an eluent in micro matrix solid phase dispersion and plays a dual role throughout the analytical procedure, including extraction solvent in sample preparation and micelle pseudophase during online stacking. It brings great procedure convenience to the method. The sensitivity of this method can improve up to 1283-folds compared with the normal mode. Moreover, the overall strategy indicates satisfied green potential evaluated by greenness assessment tools

Surface-active agent enhanced FRET effect Cu-doped NH2-MIL-88(Fe) for highly sensitive detection of 3-nitro-L-tyrosine

In this study, Cu-doped NH2-MIL-88(Fe) metal–organic frameworks (MOF) were synthesized via a one-step method. Characterization techniques such as XPS, XRD and FTIR confirmed the successful incorporation of Cu2+ into NH2-MIL-88(Fe), naming this MOF as NH2-MIL-88(Fe)@Cu2+. This MOF was employed to develop a highly sensitive fluorescence sensing platform for detecting 3-nitro-L-tyrosine(3-NT). The potential for fluorescence resonance energy transfer (FRET) was suggested by the spectral overlap between NH2-MIL-88(Fe)@Cu2+'s emission and 3-NT's UV absorption. To augment this effect, cationic surfactant hexadecyltrimethylammonium bromide (CTAB), which self-assembled into nanostructured microspheres above its critical micelle concentration, was utilized. The charged surface of these microspheres, formed by the self-assembly of CTAB, is bound to the MOF surface through electrostatic force and simultaneously attracts 3-NT. Adjusting the solution's pH strengthened the interaction between NH2-MIL-88(Fe)@Cu2+ and 3-NT, thereby enhancing their mutual FRET interaction. Experimental results indicated that CTAB's introduction markedly improved the FRET effects, potentially converting a weak FRET into a strong one and enhancing detection sensitivity and accuracy. Under optimal conditions, NH2-MIL-88(Fe)@Cu2+ detected 3-NT within 0–30 μM range, with a limit of detection (LOD, S/N = 3) of 41.1 nM. Finally, the applicability of the sensor is tested by calibrating measurements in fetal bovine serum samples, achieving good performance in terms of sensitivity, selectivity and reproducibility. This research provides a method for efficient and highly sensitive 3-NT detection and insights into the FRET effect between MOF and target molecules, likely advancing related fields and inspiring future fluorescence sensor designs.

A novel entropy-driven dual-output mode integrated with DNAzyme for enhanced microRNA detection

Accurate microRNA (miRNA) detection is pivotal in the diagnosis and monitoring of cancer. Entropy-driven catalysis (EDC) has attracted widespread attention as an enzyme-free, isothermal technique for miRNA detection owing to its inherent simplicity and reliability. However, conventional EDC is a single-output mode, limiting the efficiency of signal amplification. In this study, a novel EDC dual-output mode was employed in conjunction with DNAzyme, resulting in the development of an EDC dual-end DNAzyme (EDC-DED) approach for highly sensitive miRNA detection. In this system, miRNA-21 initiated the EDC reaction, producing a large amount of catalytically active dual-end Mg2+-dependent DNAzyme. The DNAzyme further cleaved the reporter cyclically, generating a notably amplified fluorescence signal. The proposed method achieved a low detection limit of 2 pM. Compared with the traditional EDC single-end DNAzyme (EDC-SED) strategy, the present method exhibited superior amplification efficiency, enhancing detection sensitivity by approximately 46.5-fold. Furthermore, this platform demonstrated ideal specificity, satisfactory reproducibility and acceptable detection capabilities in clinical serum samples. Therefore, the straightforward and convenient strategy is a potential tool for miRNA analysis, which may provide a new perspective for biological analysis and clinical application.

Multi-scale perceptual YOLO for automatic detection of clue cells and trichomonas in fluorescence microscopic images

Vaginitis is a common disease among women and has a high recurrence rate. The primary diagnosis method is fluorescence microscopic inspection, but manual inspection is inefficient and can lead to false detection or missed detection. Automatic cell identification and localization in microscopic images are necessary. For vaginitis diagnosis, clue cells and trichomonas are two important indicators and are difficult to be detected because of the different scales and image characteristics. This study proposes a Multi-Scale Perceptual YOLO (MSP-YOLO) with super-resolution reconstruction branch to meet the detection requirements of clue cells and trichomonas. Based on the scales and image characteristics of clue cells and trichomonas, we employed a super-resolution reconstruction branch to the detection network. This branch guides the detection branch to focus on subtle feature differences. Simultaneously, we proposed an attention-based feature fusion module that is injected with dilated convolutional group. This module makes the network pay attention to the non-centered features of the large target clue cells, which contributes to the enhancement of detection sensitivity. Experimental results show that the proposed detection network MSP-YOLO can improve sensitivity without compromising specificity. For clue cell and trichomoniasis detection, the proposed network achieved sensitivities of 0.706 and 0.910, respectively, which were 0.218 and 0.051 higher than those of the baseline model. In this study, the characteristics of the super-resolution reconstruction task are used to guide the network to effectively extract and process image features. The novel proposed network has an increased sensitivity, which makes it possible to detect vaginitis automatically.

A Novel CRISPR/Cas12a-Mediated Ratiometric Dual-Signal Electrochemical Biosensor for Ultrasensitive and Reliable Detection of Circulating Tumor Deoxyribonucleic Acid.

Circulating tumor DNA (ctDNA) holds great promise as a noninvasive biomarker for cancer diagnosis, treatment, and prognosis. However, the accurate and specific quantification of low-abundance ctDNA in serum remains a significant challenge. This study introduced, for the first time, a novel exponential amplification reaction (EXPAR)-assisted CRISPR/Cas12a-mediated ratiometric dual-signal electrochemical biosensor for ultrasensitive and reliable detection of ctDNA. To implement the dual-signal strategy, a signal unit (ssDNA-MB@Fc/UiO-66-NH2) was prepared, consisting of methylene blue-modified ssDNA as the biogate to encapsulate ferrocene signal molecules within UiO-66-NH2 nanocarriers. The presence of target ctDNA KRAS triggered EXPAR amplification, generating numerous activators for Cas12a activation, resulting in the cleavage of ssDNA-P fully complementary to the ssDNA-MB biogate. Due to the inability to form a rigid structure dsDNA (ssDNA-MB/ssDNA-P), the separation of ssDNA-MB biogate from the UiO-66-NH2 surface was hindered by electrostatic interactions. Consequently, the supernatant collected after centrifugation exhibited either no or only a weak presence of Fc and MB signal molecules. Conversely, in the absence of the target ctDNA, the ssDNA-MB biogate was open, leading to the leakage of Fc signal molecules. This clever ratiometric strategy with Cas12a as the "connector", reflecting the concentration of ctDNA KRAS based on the ratio of the current intensities of the two electroactive signal molecules, enhanced detection sensitivity by at least 60-300 times compared to single-signal strategies. Moreover, this strategy demonstrated satisfactory performance in ctDNA detection in complex human serum, highlighting its potential for cancer diagnosis.

Tuning the Dynamic Reaction Balance of CRISPR/Cas12a and RPA in One Pot: A Key to Switch Nucleic Acid Quantification.

Excavating nucleic acid quantitative capabilities by combining clustered regularly interspaced short palindromic repeats (CRISPR) and isothermal amplification in one pot is of common interest. However, the mutual interference between CRISPR cleavage and isothermal amplification is the primary obstacle to quantitative detection. Though several works have demonstrated enhanced detection sensitivity by reducing the inhibition of CRISPR on amplification in one pot, few paid attention to the amplification process and even dynamic reaction processes between the two. Herein, we find that DNA quantification can be realized by regulating either recombinase polymerase amplification (RPA) efficiency or CRISPR/Cas12a cleaving efficiency (namely, tuning the dynamic reaction balance) in one pot. The sensitive quantification is realized by utilizing dual PAM-free crRNAs for CRISPR/Cas12a recognition. The varied RPA primer concentration with stabilized CRISPR systems significantly affects the amplification efficiency and quantitative performances. Alternatively, quantitative detection can also be achieved by stabilizing the amplification process while regulating the CRISPR/Cas12a concentration. The quantitative capability is proved by detecting DNA targets from Lactobacillus acetotolerans and SARS-CoV-2. The quantitative performance toward real samples is comparable to quantitative real-time PCR for detecting L. acetotolerans spiked in fermented food samples and SARS-CoV-2 clinical samples. We expect that the presented method will be a powerful tool for quantifying other nucleic acid targets.

Pressure-resistant and portable array gas membrane device for rapid Escherichia coli detection in infant milk powder via smartphone colorimetry with all-in-one preparation strategy

This study presents a novel Pressure-Resistant and Portable Array Gas Membrane Separation (PAGMS) device for the rapid, smartphone-based detection of Escherichia coli (E. coli) in infant milk powder. The PAGMS device efficiently separates acetic acid, a byproduct of E. coli growth, enhancing detection sensitivity. Utilizing bromocresol violet as an indicator, this method quantifies E. coli based on colorimetric changes, with UV spectrum absorbance shifts indicating a linear correlation (R2 = 0.9864) within 5.0–120 μmol/L acetic acid concentration. Visual MINTEQ simulations validate the mechanism behind the indicator’s response. The approach surpasses traditional plate culture methods in terms of sample preparation time, achieving detection within a comparable timeframe of 15 min, and can concurrently process up to 48 samples, thereby substantially enhancing analytical throughput while detecting E. coli with a limit of detection of 5 cfu/g. This method demonstrates enhanced sensitivity, speed, and high-throughput capabilities, offering significant advantages in food safety monitoring.

Concomitant investigation of crustacean amphipods lipidome and metabolome during the molting cycle by Zeno SWATH data-independent acquisition coupled with electron activated dissociation and machine learning

BackgroundDIA (Data-Independent Acquisition) is a powerful technique in Liquid Chromatography coupled with high-resolution tandem Mass Spectrometry (LC-MS/MS) initially developed for proteomics studies and recently emerging in metabolomics and lipidomics. It provides a comprehensive and unbiased coverage of molecules with improved reproducibility and quantitative accuracy compared to Data-Dependent Acquisition (DDA). Combined with the Zeno trap and Electron-Activated Dissociation (EAD), DIA enhances data quality and structural elucidation compared to conventional fragmentation under CID. These tools were applied to study the lipidome and metabolome of the freshwater amphipod Gammarus fossarum, successfully discriminating stages and highlighting significant biological features. Despite being underused, DIA, along with the Zeno trap and EAD, holds great potential for advancing research in the omics field. ResultsDIA combined with the Zeno trap enhances detection reproducibility compared to conventional DDA, improving fragmentation spectra quality and putative identifications. LC coupled with Zeno-SWATH-DIA methods were used to characterize molecular changes in reproductive cycle of female gammarids. Multivariate data analysis including Principal Component Analysis and Partial Least Square Discriminant Analysis successfully identified significant features. EAD fragmentation helped to identify unknown features and to confirm their molecular structure using fragmentation spectra database annotation or machine learning. EAD database matching accurately annotated five glycerophospholipids, including the position of double bonds on fatty acid chain moieties. SIRIUS database predicted structures of unknown features based on experimental fragmentation spectra to compensate for database incompleteness. SignificanceReproducible detection of features and confident identification of putative compounds are pivotal stages within analytical pipelines. The DIA approach combined with Zeno pulsing enhances detection sensitivity and targeted fragmentation with EAD in positive polarity provides orthogonal fragmentation information. In our study, Zeno-DIA and EAD thereby facilitated a comprehensive and insightful exploration of pertinent biological molecules associated with the reproductive cycle of gammarids. The developed methodology holds great promises for identifying informative biomarkers on the health status of an environmental sentinel species.

Determination of genotoxic impurities of aromatic aldehydes in pharmaceutical preparations by high performance liquid chromatography after derivatization with N-Cyclohexyl-4-hydrazino-1,8-naphthalenediimide

The detection of aromatic aldehydes, considered potential genotoxic impurities, holds significant importance during drug development and production. Current analytical methods necessitate complex pre-treatment processes and exhibit insufficient specificity and sensitivity. This study presents the utilization of naphthalenediimide as a pre-column derivatisation reagent to detect aromatic aldehyde impurities in pharmaceuticals via high-performance liquid chromatography (HPLC). We screened a series of derivatisation reagents through density functional theory (DFT) and investigated the phenomenon of photoinduced electron transfer (PET) for both the derivatisation reagents and the resulting products. Optimal experimental conditions for derivatisation were achieved at 40 °C for 60 min. This approach has been successfully applied to detect residual aromatic aldehyde genotoxic impurities in various pharmaceutical preparations, including 4-Nitrobenzaldehyde, 2-Nitrobenzaldehyde, 1,4-Benzodioxane-6-aldehyde, and 5-Hydroxymethylfurfural. The pre-column derivatisation method significantly enhanced detection sensitivity and reduced the limit of detection (LOD), which ranged from 0.002 to 0.008 μg/ml for the analytes, with relative standard deviations < 3 %. The correlation coefficient (R2) >0.998 demonstrated high quality. In chloramphenicol eye drops, the concentration of 4-Nitrobenzaldehyde was measured to be 8.6 µg/mL below the specified concentration, with recoveries ranging from 90.0 % to 119.2 %. In comparison to existing methods, our work simplifies the pretreatment process, enhances the sensitivity and specificity of the analysis, and offers comprehensive insights into impurity detection in pharmaceutical preparations.

Modulation by Co (II) Ion of Optical Activities of L/D-glutathione (GSH)-modified Chiral Copper Nanoclusters for Sensitive Adenosine Triphosphate Detection.

Chiral nanoscale enantiomers exhibit different biological effects in living systems. However, their chirality effect on the detection sensitivity for chiral biological targets still needs to be explored. Here, we discovered that Co2+ can modulate the luminescence performance of L/D-glutathione (GSH)-modified copper nanoclusters (L/D-Cu NCs) and induce strong chiroptical activities as the asymmetric factor was enhanced 223-fold with their distribution regulating from the ultraviolet to visible region. One Co2+ coordinated with two GSH molecules that modified on the surface of Cu NCs in the way of CoN2O2. On this basis, dual-modal chiral and luminescent signals of Co2+ coordinated L/D-Cu NCs (L/D-Co-Cu NCs) were used to detect the chiral adenosine triphosphate (ATP) based on the competitive interaction between surficial GSH and ATP molecules with Co2+. The limits of detection of ATP obtained with fluorescence and circular dichroism intensity were 9.15 μM and 15.75 nM for L-Co-Cu NCs, and 5.35 μM and 4.69 nM for D-Co-Cu NCs. This demonstrated that selecting suitable chiral configurations of nanoprobes effectively enhances detection sensitivity. This study presents not only a novel method to modulate and enhance the chiroptical activity of nanomaterials but also a unique perspective of chirality effects on the detection performances for bio-targets.

Modulation by Co (II) Ion of Optical Activities of L/D‐glutathione (GSH)‐modified Chiral Copper Nanoclusters for Sensitive Adenosine Triphosphate Detection

AbstractChiral nanoscale enantiomers exhibit different biological effects in living systems. However, their chirality effect on the detection sensitivity for chiral biological targets still needs to be explored. Here, we discovered that Co2+ can modulate the luminescence performance of L/D‐glutathione (GSH)‐modified copper nanoclusters (L/D−Cu NCs) and induce strong chiroptical activities as the asymmetric factor was enhanced 223‐fold with their distribution regulating from the ultraviolet to visible region. One Co2+ coordinated with two GSH molecules that modified on the surface of Cu NCs in the way of CoN2O2. On this basis, dual‐modal chiral and luminescent signals of Co2+ coordinated L/D−Cu NCs (L/D−Co−Cu NCs) were used to detect the chiral adenosine triphosphate (ATP) based on the competitive interaction between surficial GSH and ATP molecules with Co2+. The limits of detection of ATP obtained with fluorescence and circular dichroism intensity were 9.15 μM and 15.75 nM for L−Co−Cu NCs, and 5.35 μM and 4.69 nM for D−Co−Cu NCs. This demonstrated that selecting suitable chiral configurations of nanoprobes effectively enhances detection sensitivity. This study presents not only a novel method to modulate and enhance the chiroptical activity of nanomaterials but also a unique perspective of chirality effects on the detection performances for bio‐targets.

Research on the Flow Characteristics and Reaction Mechanisms of Lateral Flow Immunoassay under Non-Uniform Flow.

Lateral flow immunoassay (LFIA) is extensively utilized for point-of-care testing due to its ease of operation, cost-effectiveness, and swift results. This study investigates the flow dynamics and reaction mechanisms in LFIA by developing a three-dimensional model using the Richards equation and porous media transport, and employing numerical simulations through the finite element method. The study delves into the transport and diffusion behaviors of each reaction component in both sandwich LFIA and competitive LFIA under non-uniform flow conditions. Additionally, the impact of various parameters (such as reporter particle concentration, initial capture probe concentrations for the T-line and C-line, and reaction rate constants) on LFIA performance is analyzed. The findings reveal that, in sandwich LFIA, optimizing parameters like increasing reporter particle concentration and initial capture probe concentration for the T-line, as well as adjusting reaction rate constants, can effectively enhance detection sensitivity and broaden the working range. Conversely, in competitive LFIA, the effects are inverse. This model offers valuable insights for the design and enhancement of LFIA assays.

Ultrasensitive Electrochemical Immunosensor for Multiplex Sandwich Bioassaying Based on the Functional Antibodies.

In vitro diagnostics (IVDs) based on electrochemical immunosensors are crucial for disease screening, diagnosis, prognosis, and treatment monitoring. However, label-free electrochemical immunosensors commonly suffer from poor specificity, leading to false positives. To address this issue, we propose a highly sensitive and precise electrochemical immunosensor for protein marker detection. This approach involves directly labeling the detection antibodies (Ab2) with thionine (Thi). The Ab2 labeled by Thi exhibits a distinct redox peak upon targeted voltage stimulation, enabling accurate quantification of protein biomarkers. Thi-modified antibodies provide significant advantages over traditional antibody modification methods, such as enhanced detection sensitivity, improved accuracy, and specificity in protein marker identification. The method is straightforward and efficient, ensuring specific analyte detection while minimizing interference from other substances in the sample. Additionally, a multielectrode detection method was employed, achieving remarkably low limits of detection (LoDs) for tumor necrosis factor-alpha (TNF-alpha), cardiac troponin I (cTnI), and interleukin-6 (IL-6), with LoDs of 9.38 fg/mL, 1.70 fg/mL, and 8.14 fg/mL, respectively. The proposed electrochemical immunosensor also exhibited high selectivity and repeatability, with relative standard deviations (RSD) of 6.39% for TNF-alpha, 2.42% for cTnI, and 2.72% for IL-6 (n = 5). Moreover, it demonstrated high sensitivity and was evaluated for serum detection using the standard addition method. The results highlight the great potential of the proposed electrochemical immunosensor for clinical applications, offering a novel approach for future utilization in clinical settings.

Fiber SPR Sensor Based on S-Taper Sensitivity Enhancement for Nickel Ion Detection

Fiber SPR Sensor Based on S-Taper Sensitivity Enhancement for Nickel Ion Detection