Talanta

Cardiovascular disease (CVD) is a serious worldwide health concern that necessitates the development of novel diagnostic techniques for early identification and personalized healthcare management. Even before the insights provided by gut microbiota, current research has demonstrated the importance of circulating microbiome (CMB) in the evolution of cardiometabolic illness risk and progression. We developed a nanobiosensor that uses specific labeled capture probes with perovskite quantum dots (PQDs) to detect the targeted 16S rRNA sequences in the peripheral milieu. With ideal applicability, specificity, and sensitivity, this sensor delivers unique insights into the presence and characterization of circulating microbiota signatures. Developing a nanophotonic microbiome detection method in body fluids may pave the way for creating a distinctive tool for CVD risk prediction for population-based screening programs in low and middle-income countries.

Early diagnosis of bacterial causing the disease is important for treatment of patent and preventing the spread of pathogen. Utilizing of POCT devices to detect the pathogens on-site will accelerate the diagnosis of infectious disease. By using loop-mediated-amplification, we developed a microfluidic chip for multiplex detection of three bacterial, where the samples were driven by negative pressure were loaded quickly. The performance of the device was preliminarily evaluated. The specificities of the detections were demonstrated. And the LOD for Escherichia coli, Staphylococcus aureus and Pseudomonas aeruginosa were measured as 17.15, 5.67 and 16.47 ng/L, respectively. The results demonstrated the feasibility of the method.

Developing rapid and highly sensitive methods for alkaline phosphatase (ALP) activity analysis is significant for the clinical diagnosis and treatment of diseases. Here, a Pyrococcus furiosus Argonaute (PfAgo)-based biosensor is presented for ALP activity detection in which the ALP-catalyzed hydrolysis of 3-phosphate-modified functional DNA activates the strand displacement amplification, and the amplicon -mediates the fluorescent reporter cleavage as a guide sequence of PfAgo. Under the dual amplification mode of PfAgo-catalyzed multiple-turnover cleavage activity and pre-amplification technology, the developed method was successfully applied in ALP activity analysis with a detection limit (LOD) of 0.0013 U L-1 (3{sigma}) and a detection range of 0.0025 U L-1 to 1 U L-1 within 90 min. The PfAgo-based method exhibits satisfactory analytic performance in the presence of the potential interferents and in complex human serum samples. The proposed method shows several advantages, such as rapid, highly sensitive, low-cost, and easy operation, and has great potential in disease evolution fundamental studies and clinical diagnosis applications.

Cystatin-C is an important renal function biomarker, and conventional quantification requires centralized laboratory analyzers, which limits timely testing in primary care and resource-limited settings. To address this need, we developed and validated a simple, rapid, and quantitative smartphone-based (SP) lateral flow immunoassay (LFIA) for measuring serum Cystatin-C. The SP-LFIA platform consists of a colorimetric LFIA strip and a custom SP reader with uniform LED illumination and macro lens for image capture. Quantitative image analysis of the colorimetric signal is performed by a dedicated application using a pre-defined third order polynomial calibration model. Following systematic optimization, the assay demonstrated a wide quantitative range of 0.32-8.00 mg/L, with a limit of detection of 0.15 mg/L. Analytical validation conducted according to CLSI guidelines showed excellent precision, with intra- and inter-assay coefficients of variation below 10%, and no significant interference from bilirubin, triglycerides, hemoglobin, or rheumatoid factor. Accelerated stability testing confirmed robust strip performance after storage at 50 {degrees}C for 28 days. Method comparison using 100 clinical serum samples showed high agreement with a commercial PETIA reference method (R{superscript 2} = 0.993) and minimal bias. These results indicate that the developed smartphone-based LFIA provides a reliable, cost-effective, and practical tool for point-of-care Cystatin-C monitoring.

Foodborne bacteria are major causes that affect human health. Development of new method that could achieve Rapid, sensitive and quantitative detection of pathogen is urgently needed. In this research, a step emulsion microfluidic,combined with droplet-based digital-RPA, was developed to detect Vibrio parahaemolyticus, a major seafood-borne pathogenic bacteria. Specific and rapid detection of Vibrio parahaemolyticus in 30 min has been achieved by this new device, with a detection limit of 10 CFU/L, about 10-times lower than classical tube-based RPA. This device was demonstrated to be a promising tool for detection of pathogenic bacteria.

Volatile organic compounds (VOCs) are common constituents of fruits, vegetables, and crops, and are closely associated with their quality attributes, such as firmness, sugar level, ripeness, translucency, and pungency levels. While VOCs are vital for assessing vegetable quality, traditional detection methods, such as Gas Chromatography-Mass Spectrometry (GC-MS) and Proton Transfer Reaction Mass Spectrometry (PTR-MS) are limited by expensive equipment, complex sample preparation, and slow turnaround time. Additionally, the transient nature of VOCs complicates their detection using these methods. Here, we developed a paper-based colorimetric sensor array combined with needles that could induce vegetable VOC release in a minimally invasive fashion and analyze VOCs in situ with a smartphone reader device. The colorimetric sensor array was optimized using sulfur compounds as main targets and classified fourteen different vegetable VOCs, including sulfoxides, sulfides, mercaptans, thiophenes, and aldehydes. By combining principal components analysis (PCA) analysis, the integrated sensor platform proficiently discriminated between four vegetable subtypes originating from two major categories within 2 min of testing time. This rapid and minimally invasive sensing technology holds great promise for conducting field-based vegetable quality monitoring. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=133 SRC="FIGDIR/small/628229v1_ufig1.gif" ALT="Figure 1"> View larger version (44K): org.highwire.dtl.DTLVardef@12bf541org.highwire.dtl.DTLVardef@f2a809org.highwire.dtl.DTLVardef@f5f5b7org.highwire.dtl.DTLVardef@1d7027f_HPS_FORMAT_FIGEXP M_FIG C_FIG

Digital polymerase chain reaction (PCR) is a fast-developed technology, which makes it possible to provide absolute quantitative results. However, this technology has not been widely used in research field or clinical diagnostics. Although digital PCR has been born for two decades, the products on this subject still suffer from either high cost or cumbersome user experience, hence very few labs have the willingness or budget to routinely use such product; On the other hand, the unique sensitivity of dPCR over traditional qPCR shows great potential applications. Here, a cost-effective digital PCR method based on a microfluidic printing system was introduced, trying to overcome those shortcomings. The microfluidic droplet printing technology was utilized in this study to directly generate droplet array containing PCR reaction solution onto the simple glass substrate for the subsequent PCR and imaging, which could be done with any regular flat-panel PCR machine and microscope. The method introduces a new perspective in droplet-based digital PCR in that the droplets generated with this method aligns well in an array without touch with each other, therefore the regular glass and oil could be used without any special surfactant. With simple analysis, the data generated with this method showed reliable quality, which followed the Poisson distribution trend. Compared with other expensive digital PCR methods, this system is more affordable and simpler to integrate, especially for those biological or medical labs which are in need for the digital PCR options but short in budget. Therefore, this method is believed to have the great potential in the future market application.

The postsynaptic density (PSD) is a complex, multi-layered protein network largely situated on the internal surface of the postsynaptic membrane. It is the first processing unit for incoming synaptic transmissions, and changes in its internal structure are associated with synaptic strength and plasticity. These structural changes are largely governed by multivalent interactions between its components. The in vitro characterization of such complexes requires unbiased methods that can be used to estimate the size of the emerging assemblies for systems with multiple possible stoichiometries. Here we present an experimental method for detecting specific PSD proteins as well as their complexes based on their diffusion in a microfluidic environment. The method requires a fluorescent labelling technique that does not disrupt the function of labelled proteins, a microfluidic device that can maintain laminar flow for protein solutions, a microscope that can record the fluorescent signal emitted by these solutions, and an analytic software package that can process the collected experimental data and convert them into approximate particle sizes. We demonstrate the applicability of our method on protein constructs of various postsynaptic proteins, including the multivalent assembly between GKAP and LC8.

SARS-CoV-2 causes ongoing infections worldwide, and identifying people with immunity is becoming increasingly important. Available point-of-care diagnostic systems as lateral flow assays have high potential for fast and easy on-site antibody testing but are lacking specificity, sensitivity or possibility for quantitative measurements. Here, a new point-of-care approach for SARS-CoV-2 specific antibody detection in human serum based on magnetic immuno-detection is described and compared to standard ELISA. For magnetic immuno-detection, immunofiltration columns were coated with a SARS-CoV-2 spike protein peptide. SARS-CoV-2 peptide reactive antibodies, spiked at different concentrations into PBS and human serum, were rinsed through immunofiltration columns. Specific antibodies were retained within the IFC and labelled with an isotype specific biotinylated antibody. Streptavidin-functionalized magnetic nanoparticles were applied to label the secondary antibodies. Enriched magnetic nanoparticles were then detected by means of frequency magnetic mixing detection technology, using a portable magnetic read-out device. Measuring signals corresponded to the amount of SARS-CoV-2 specific antibodies in the sample. Our preliminary magnetic immuno-detection setup resulted in a higher sensitivity and broader detection range and was four times faster than ELISA. Further optimizations could reduce assay times to that of a typical lateral flow assay, enabling a fast and easy approach, well suited for point-of-care measurements without expensive lab equipment.

To overcome the technical bottlenecks in the precise quantification and molecular typing of viable foodborne pathogens, this study establishes a microfluidic droplet digital PCR (ddPCR) based method for rapid and accurate detection and quantification of viable Listeria monocytogenes with clonal specificity. In contrast to the time-consuming plate culture methods and unspecific rapid detection methods, the method in this study employs clonal complex (CC) specific primers and probe for strain-specificity and integrate the nucleic acid dye propidium monoazide (PMA) to effectively distinguish viable from dead bacteria. The rapid and precise quantification of viable bacteria is achieved through microdroplet counting. This method does not require DNA extraction, and the entire detection process takes only about 3 hours, with a quantitative detection limit of 3.3x102 CFU/mL, providing strong technical support for the risk monitoring of highly pathogenic specific types of L. monocytogenes.

Polymerase chain reaction (PCR) is a method widely used to amplify trace amount of nucleic acids. It needs a process of thermocycling (repeated alternation of temperature). Traditional thermocycler relies on bulk size of metal block to achieve thermocycling, which results in high cost and the lack of portability. Here, a PCR chip made of graphene Transparent Conductive Films (TCFs) was employed. The thermocycling of the chip was fulfilled by a temperature programed microcontroller and a cooling fan under a low driving voltage (12V). A 35 cycles PCR was accomplished within 13 minutes using the chip and the thermocycler. The transparency of the graphene PCR chip enables the PCR reaction to be visually monitored by naked eye for a color change. The PCR chip and the thermocycler have a low cost at $2.5 and $6 respectively, and thus are feasible for Point-of-care testing (POCT) of nucleic acids in a disposable manner. The whole platform makes it possible to perform a low-cost testing of nucleic acids for varieties of purposes outside of laboratories or at resource limited locations.

Hybridization of fluorescent molecular probes, such as molecular beacons or linear molecular probes, with their molecular targets can be confirmed through fluorescence spectra. In this study, we investigate the interaction between fluorescent probes, specifically linear molecular probes, and their targets in the presence of chaotropic agents. Our findings show that double-stranded structures containing mismatched nucleotides (e.g., single-nucleotide polymorphisms) occupy lower energy levels (red shifted) compared to those without mismatched nucleotides. Molecular duplexes formed in buffers without chaotropic agents do not exhibit significant differences, independently on whether they contain mismatched nucleotides or are formed with perfectly matching targets. This effect appears in the presence of a naturally occurring chaotropic agent, urea, and was confirmed in the concentration range of 1 mM to 4 mM. These findings suggest that urea and similar agents may play a significant role in the formation of mismatched nucleotide structures.

In recent decades, nanopores have become a promising diagnostic tool. Protein and solid-state nanopores are increasingly used for both RNA/DNA sequencing and small molecule detection. The latter is of great importance because small molecules are difficult or expensive to detect using available methods such as HPLC or LC-MS. Moreover, DNA aptamers are an excellent detection element for sensitive and specific detection of small molecules. Here, we describe a method for the quantification of ethanolamine using Oxford Nanopores ready-to-use sequencing platform. To this end, we have developed a strand displacement assay using a binding ethanolamine aptamer and magnetic beads. The displaced aptamer can be detected using the MinION(R) nanopores and analysed/quantified using our in-house developed analysis software.

There are various techniques for detecting recombinant proteins such as western blot, SDS-PAGE, ELISA and fluorescence microscopy. However, these methods are difficult to handle, time-consuming and need special tools. We developed a rapid, inexpensive, sensitive, and straightforward approach to address these problems using an Antihistidine biosensor. Colloidal gold nanoparticles (GNPs) were synthesized by chitosan as reducer and stabilizer via the green synthesis method. Then, anti-His tag antibody was immobilized on the Chitosan-gold nanoparticles (CS-GNPs) surface to visually detect spotted target protein on nitrocellulose (NC) membrane. Our results showed that the designed dot-blot immunoassay can detect histidine-tagged recombinant proteins with the limit of detection (LOD) of 1{micro}g/ml without any signal enhancement directly from cell lysate within 5 minutes. In an extra step, we applied HAuCl4 and NH2OH\ HCl as a gold enhancement system and increased the detection sensitivity to 0.1 {micro}g/ml. The results showed that the developed assay can rapidly detect production of recombinant proteins, and it can be used as a screening method in low-resource laboratories.

BackgroundThe clinical translation of molecularly targeted therapeutics and imaging agents represents a cornerstone of precision oncology, with the global theranostics market projected to exceed $25 billion by 2030. However, the development of theragnostic agents or diagnostic companions remains constrained by analytical bottlenecks in quality control, such as target-binding specificity, which are increasingly required by regulatory agencies as product release criteria during the translation process. Current methods, including enzyme-linked immunosorbent assay (ELISA), which require specialized resources or external CROs, or bead-based assays for radiolabeled compounds, which involve complex multi-step protocols; these limitations and others hamper their practical implementation in clinical manufacturing environments. Assay delays can postpone clinical trial initiation, increase development costs, and delay patient access to these agents. ResultsWe have developed and validated a rapid, size-exclusion high-performance liquid chromatography (SE-HPLC) method for the determination of target-binding fractions of labeled biologics. The method separates the unbound biologic from the larger antigen-bound complex, allowing for rapid quantification. We validated the method using a panel of fluorescently labeled antibodies (panitumumab-IRDye800CW, nivolumab-IRDye800CW) and radiolabeled biologics ([18F]GEH200521, [18F]NOTA-ABY-030), assessing linearity, specificity, and concentration independence. The SE-HPLC method achieved excellent separation of bound and unbound species with a resolution (Rs) of 3.2. A strong linear relationship (R2 = 0.999) was observed between the antigen-to-antibody ratio and the measured binding fraction. The method demonstrated high specificity, with no binding detected with non-target antigens. The total assay and analysis time was less than 35 minutes, a significant improvement over traditional methods. ConclusionsSE-HPLC provides a rapid, specific, and cost-effective alternative to traditional binding fraction assessment methods, reducing quality control timelines from weeks/hours to minutes. The methods compatibility with both fluorescent and radiolabeled biologics and integration with existing HPLC infrastructure represents a significant advancement in development workflows.

There are various protein assays for specific and quantitative detection and widely used for laboratory and clinic purposes, but current methods still have limitations. Immunoassays based on antibodies, like ELISA, suffer from slow response and a long antibody-screening period, while physical or electrochemical methods are generally restricted by high cost or the stringent requirement of equipment or operating skills. In this study, we developed an in vitro sensitive protein quantification method: Captamer. The Captamer system comprises a molecular switch derived from aptamer sequence and an exponential fluorescence signal amplification pathway based on recombinase polymerase amplification (RPA). We demonstrated the Captamer for SARS-CoV-2 nucleocapsid protein detection and obtained results from samples within 30 min, displaying a wide detection window from 0.2 pg/mL to 200 pg/mL with high specificity. Furthermore, we tested the Captamer for Tau441 protein (a potential Alzheimers disease biomarker) and thrombin (a classic aptamer-protein interaction model), showing the limit of detection as low as 1 ng/mL and 0.02pg/mL respectively, which suggested the capacity of Captamer to be applied to various aptamer-protein pairs. Compared with the most commonly used and recently reported protein quantification methods, Captamer stands out for its high sensitivity, short response time, low cost, and simplicity, indicating its great potential to be widely used in protein quantification. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=131 SRC="FIGDIR/small/686180v1_ufig1.gif" ALT="Figure 1"> View larger version (32K): org.highwire.dtl.DTLVardef@1e38ffaorg.highwire.dtl.DTLVardef@1019e72org.highwire.dtl.DTLVardef@1498b68org.highwire.dtl.DTLVardef@15f5ea2_HPS_FORMAT_FIGEXP M_FIG C_FIG

1The ongoing outbreak of the novel coronavirus disease 2019 (COVID-19) originating from Wuhan, China, draws worldwide concerns due to its long incubation period and strong infectivity. Although RT-PCR-based molecular diagnosis techniques are being widely applied for clinical diagnosis currently, timely and accurate diagnosis are still limited due to labour intensive and time-consuming operations of these techniques. To address the issue, herein we report the synthesis of poly (amino ester) with carboxyl groups (PC)-coated magnetic nanoparticles (pcMNPs), and the development of pcMNPs-based viral RNA extraction method for the sensitive detection of COVID-19 causing virus, the SARS-CoV-2. This method combines the lysis and binding steps into one step, and the pcMNPs-RNA complexes can be directly introduced into subsequent RT-PCR reactions. The simplified process can purify viral RNA from multiple samples within 20 min using a simple manual method or an automated high-throughput approach. By identifying two different regions (ORFlab and N gene) of viral RNA, a 10-copy sensitivity and a strong linear correlation between 10 and 105 copies of SARS-CoV-2 pseudovirus particles are achieved. Benefitting from the simplicity and excellent performances, this new extraction method can dramatically reduce the turn-around time and operational requirements in current molecular diagnosis of COVID-19, in particular for the early clinical diagnosis.

In the current study, for rapid detection of azocylotin residues in agricultural products, the Co3O4/PAn nanoparticles modified electrochemical immunosensor was generated successfully. Azocylotin-BSA artificial antigen coupling to the surface of the working electrode coated with the Co3O4/PAn nanoparticles thin-layer, the competitive inhibition reaction is launched between the azocylotin in the samples and the azocylotin coupled on the electrode with the azocylotin monoclonal antibodies in the test system. The antigen-antibody reaction signal conductive amplified by the coupled silver nanoparticles, and then the electrolytic current in the reaction system was detected. After establishing basic detection system, a series of optimization including the concentration of immobilized membrane optimization, electrode surface coated material composition optimization, selection of buffer, coupling antigen concentration optimization and anti-antibody label optimization will be done. Subsequently, the concentrations of azocylotin in samples of standards, orange and apple were tested, and the results indicated that this immune sensor has good sensitivity and high accuracy. The research could provide the reference for the research, development and application of sensors to realize rapid detection of pesticide residues in agricultural products.

Antimicrobial resistance is one of the top global health threats; it is associated with millions of deaths per year. Traditional and most commonly used antibiotic susceptibility tests are based on detection of bacterial growth and its inhibition in the presence of an antimicrobial. These tests typically take over 1-2 days to perform, so empirical therapy schemes are often administered before the proper testing. Rapid tests for antimicrobial resistance are necessary to optimize the treatment of bacterial infection. A combination of MTT test with Raman spectroscopy to provide 1.5-hour long test antimicrobial susceptibility determination requiring 106-108 CFU/mL of bacteria. Here the first rapid antibiotic susceptibility test for trace amounts of bacteria is described. The bacterial titer can be decreased down to 102 CFU/mL using surface-enhanced Raman spectroscopy (SERS) of the MTT-treated bacteria caught with the silver coated track-etched membranes allowing the antimicrobial testing of low-titer bacterial samples within 1.5 hour. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=109 SRC="FIGDIR/small/664554v1_ufig1.gif" ALT="Figure 1"> View larger version (28K): org.highwire.dtl.DTLVardef@1e241c5org.highwire.dtl.DTLVardef@14c071forg.highwire.dtl.DTLVardef@67aad7org.highwire.dtl.DTLVardef@140db_HPS_FORMAT_FIGEXP M_FIG C_FIG A combination of MTT test with membrane filtration and surface-enhanced Raman spectroscopy is used to determine antibiotic susceptibility of E.col

Amatoxins contribute to the majority of mushroom poisoning, most prominently, -amanitin. Since mushroom is a common foodstuff worldwide, an easy, rapid, sensitive test for -amanitin is needed. Several detection methods for -amanitin have been developed, including HPLC, LC-MS, and ELISA, and LFIA. Aptamers have several advantages compared to antibodies: easy development via SELEX, longer shelf life, and higher temperature- and pH-tolerance. Aptamer Lateral Flow Assay (ALFA) is a similar technology compared to LFIA but incorporates aptamers as target-recognizing agents. This study attempted to develop an ALFA test strip for -amanitin using a previously-developed aptamer, however failure of generating a colorimetric readout at the test line is persisted throughout all experiments, even though the concept is fully-proved and the control line functions normally. The failure is attributed to the small size of the molecule, leading to immobilization difficulties on the nitrocellulose membrane to form the test line, and the hindering of effective "surround" mechanism of aptamer-target binding (instead of "adhere", when the target molecule is large, e.g. a protein). It is concluded that ALFAs for small-molecules whose aptamer-target interaction has not yet been studied and modelled in detail remains a challenge, despite ALFAs large potential.