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Effective food safety monitoring requires a multi-step approach from farm to fork, involving different methods, ranging from convenient screening devices to sophisticated laboratory confirmatory testing. However, sample transportation to routine laboratories is time-consuming and expensive. Simplified on-site sampling followed by laboratory analysis offers a potential solution. Dried blood spot (DBS) cards ensure stability and ease of sample transportation and are used in clinical testing. However, the applicability of such an approach could be broader and include the storage of dried extract from more complex (solid) matrices. Therefore, a simplified approach is presented here, using DBS cards for on-site sampling and subsequent laboratory confirmation for food contaminants. To achieve this, an analytical tool (Smartcard) was designed using 3D-printing technology. As a proof of concept, the approach was applied to detect the pesticide fipronil, which is widely used in ornamental flower production to limit pests and on poultry farms. The Smartcard can securely store the sample extracts on a DBS card (dried extract spot (DExS) card), incorporate the lateral flow immunoassay (LFIA) and immediately provide an estimate of contamination levels. After simplified in-syringe extraction of the sample, the LFIA allows direct screening of fipronil (half maximum inhibitory concentration of 6.5 µg/l with calibration standards), and the same sample extract can be directly applied to the DExS card for storage and transport to the laboratory, where analyte re-extraction and instrumental analysis is performed using ultra high-pressure liquid chromatography tandem mass spectrometry (UHPLC-MS/MS) detecting fipronil down to 0.8 µg/kg. [ABSTRACT FROM AUTHOR]

Beta-lactam antibiotic cephalexin is poorly recognized by bacterial beta-lactam binding proteins and therefore cannot be reliably detected by a group-specific receptor assay. For effective and rapid monitoring of cephalexin concentration in food products, the test systems based on high-affinity and selective binding of this antibiotic to polyclonal antibodies have been developed. The principle of the method for the test systems of enzyme-linked immunosorbent assay (ELISA) and lateral flow immunoassay (LFIA) is based on the competitive interaction of (a) cephalexin, potentially contained in the samples, and (b) a cephalexin-protein conjugate immobilized in the wells of a microplate or on the membrane of a test strip, with (c) polyclonal antibodies against cephalexin conjugated with peroxidase or adsorbed on gold nanoparticles. The high specificity of the obtained polyclonal antibodies against cephalexin and the absence of cross-reactivity to a number of cephalosporins, penicillins, and antibiotics of other classes have been confirmed. In the ELISA system in a buffer solution and in a milk matrix, the detection limit, the IC50 value, and the range of detected concentrations were 0.02, 1.0 and 0.025–100 ng/mL respectively. The limit of detection for visual and instrumental determination of cephalexin in the LFIA system were 1.5 and 0.1 ng/mL, and the working range of quantitatively measured concentrations was from 0.05 to 1.5 ng/mL. For both systems, the coefficient of variation of measurements was in the range of 2.5–8.0%. The test systems allow to detect cephalexin in milk without sample preparation. The recovery of cephalexin added to the milk samples was 90.0–106.7%. The presented developments can serve as the basis for kits of reagents for monitoring the content of cephalexin in food products. [ABSTRACT FROM AUTHOR]

Growing concerns about the health risks of melamine adulteration in food products highlight the urgent need for reliable detection methods. However, the long-term effects of chronic low-level melamine exposure remain inadequately explored. This study introduces THE ONE InstantCare platform, a portable immunoassay analyzer integrating a SpectroChip-based spectral processing unit (SPU) with lateral flow immunoassay (LFIA) for sensitive and accurate quantification of melamine in human urine. This platform provides a cost-effective, rapid, and user-friendly point-of-care (POC) solution for melamine detection. Analytical evaluations across eight melamine concentrations (0–100 parts per billion, ppb) achieved a limit of detection (LOD) of 1.91 ppb. Validation with 24 human urine samples demonstrated strong concordance with liquid chromatography–mass spectrometry (LC-MS), yielding an intraclass correlation coefficient (ICC) of 0.9220, a Pearson correlation coefficient of 0.9389, and 95% agreement in Bland–Altman analysis. High reproducibility was observed, with an intraday coefficient of variation (CV) of 6.53% and acceptable interday CV values, while interference studies confirmed reliability in the presence of common biological substances. By delivering results in approximately 10 min, THE ONE InstantCare platform significantly reduces analysis time compared to LC-MS, which typically requires several hours. This novel platform enhances food safety surveillance and advances human health risk assessments, particularly for evaluating melamine-linked kidney damage. Its versatility and robust performance make it a promising tool for environmental monitoring and clinical diagnostics, enabling the detection of diverse biomarkers with high sensitivity and reproducibility. [ABSTRACT FROM AUTHOR]

Early diagnosis is essential for the successful management of Burkholderia pseudomallei infection, but it cannot be achieved by the current gold standard culture technique. Therefore, this study aimed to develop a lateral flow immunoassay (LFIA) targeting B. pseudomallei capsular polysaccharide. The development was performed by varying nitrocellulose membrane reaction pads and chase buffers. The prototype LFIA is composed of Unisart CN95 and chase buffer containing tris-base, casein, and Surfactant 10G. The assay showed no cross-reactivity with E. coli, S. aureus, P. aeruginosa, and P. acne. The limit of detections (LODs) of the prototype LFIA was 107 and 106 CFU/mL B. pseudomallei in hemoculture medium and artificial urine, respectively. These LODs suggest that this prototype can detect melioidosis from positive hemoculture bottles but not straight from urine. Additionally, these LODs are still inferior compared to Active Melioidosis Detect (AMDTM). Overall, this prototype holds the potential to be used clinically with hemoculture bottles. However, further improvements should be considered, especially for use with urine samples. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Growing concerns about the health risks of melamine adulteration in food products highlight the urgent need for reliable detection methods. However, the long-term effects of chronic low-level melamine exposure remain inadequately explored. This study introduces THE ONE InstantCare platform, a portable immunoassay analyzer integrating a SpectroChip-based spectral processing unit (SPU) with lateral flow immunoassay (LFIA) for sensitive and accurate quantification of melamine in human urine. This platform provides a cost-effective, rapid, and user-friendly point-of-care (POC) solution for melamine detection. Analytical evaluations across eight melamine concentrations (0–100 parts per billion, ppb) achieved a limit of detection (LOD) of 1.91 ppb. Validation with 24 human urine samples demonstrated strong concordance with liquid chromatography–mass spectrometry (LC-MS), yielding an intraclass correlation coefficient (ICC) of 0.9220, a Pearson correlation coefficient of 0.9389, and 95% agreement in Bland–Altman analysis. High reproducibility was observed, with an intraday coefficient of variation (CV) of 6.53% and acceptable interday CV values, while interference studies confirmed reliability in the presence of common biological substances. By delivering results in approximately 10 min, THE ONE InstantCare platform significantly reduces analysis time compared to LC-MS, which typically requires several hours. This novel platform enhances food safety surveillance and advances human health risk assessments, particularly for evaluating melamine-linked kidney damage. Its versatility and robust performance make it a promising tool for environmental monitoring and clinical diagnostics, enabling the detection of diverse biomarkers with high sensitivity and reproducibility.

Lateral flow immunoassay (LFIA), as a well-known point-of-care testing (POCT) technique, is of vital significance in a variety of application scenarios due to the advantages of convenience and high efficiency. With rapid development of computational intelligence (CI), algorithms have played an important role in enhancing LFIA performance, and it is necessary to summary how algorithms can assist LFIA improvement for providing experiences. However, most existing works on LFIA are from biochemical field which pay more attention to material and reagent. Therefore, in this paper, a systematical survey is proposed to review works on applying mathematical tools to promote LFIA development. Particularly, a novel two-level taxonomy is designed for a better inspection, including LFIA-oriented mathematical modelling, CI-assisted post-processing and quantification in LFIA, and each level is further subdivided for in-depth understanding. In addition, from a higher viewpoint, outlooks of jointly developing POCT with other state-of-the-art techniques are presented from perspectives of implementation principle, technical approach and algorithm application. Moreover, this survey aims to highlight that applying CI methods is competent for boosting POCT development, so as to raise attentions from more areas like information science, extend deeper researches and inspire more interdisciplinary works. [ABSTRACT FROM AUTHOR]

• Approximately 89-91% of COVID-19 antibody-positive serum samples cross-reacted with dengue virus (DV). • COVID-19 serum samples, tested with DV antibody test kits, have a high false-positive rate. • SARS-CoV-2 infected patients' serum samples neutralized DV type 1 clinical isolate. • Neutralizing serum samples included many without dengue infection history. • Serological tests will be inconclusive where both the viruses are now co-endemic. Observing the serological cross-reactivity between SARS-CoV-2 and dengue virus (DV), we aimed to elucidate its effect on dengue serodiagnosis and infectivity in a highly dengue-endemic city in India. A total of 52 COVID-19 (reverse transcription-polymerase chain reaction [RT-PCR] positive) serum samples were tested in rapid lateral flow immunoassays and DV immunoglobulin G (IgG) enzyme-linked immunosorbent assay (ELISA) to detect DV or SARS-CoV-2 IgG/immunoglobulin M. The COVID-19 antibody (Ab) positive samples were subjected to a virus neutralization test (Huh7 cells) using DV type 1 (DV1) clinical isolate. Most (93%) of the SARS-CoV-2 Ab-positive serum samples cross-reacted with DV in rapid or ELISA tests. All were DV RNA and nonstructural protein 1 (NS1) antigen-negative. COVID-19 serum samples that were DV cross-reactive neutralized DV1. Of these, 57% had no evidence of DV pre-exposure (DV NS1 Ab-negative). The computational study also supported potential interactions between SARS-CoV-2 Ab and DV1. DV serodiagnosis will be inconclusive in areas co-endemic for both viruses. The COVID-19 pandemic appears to impart a protective response against DV in DV-endemic populations. [ABSTRACT FROM AUTHOR]

Extracellular vesicles (EVs) are biological nanoparticles of great interest as novel sources of biomarkers and as drug delivery systems for personalized therapies. The research in the field and clinical applications require rapid quantification. In this study, we have developed a novel lateral flow immunoassay (LFIA) system based on Fe3O4 nanozymes for extracellular vesicle (EV) detection. Iron oxide superparamagnetic nanoparticles (Fe3O4 MNPs) have been reported as peroxidase-like mimetic systems and competent colorimetric labels. The peroxidase-like capabilities of MNPs coated with fatty acids of different chain lengths (oleic acid, myristic acid, and lauric acid) were evaluated in solution with H2O2 and 3,3,5,5-tetramethylbenzidine (TMB) as well as on strips by biotin–neutravidin affinity assay. As a result, MNPs coated with oleic acid were applied as colorimetric labels and applied to detect plasma-derived EVs in LFIAs via their nanozyme effects. The visual signals of test lines were significantly enhanced, and the limit of detection (LOD) was reduced from 5.73 × 107 EVs/μL to 2.49 × 107 EVs/μL. Our work demonstrated the potential of these MNPs as reporter labels and as nanozyme probes for the development of a simple tool to detect EVs, which have proven to be useful biomarkers in a wide variety of diseases. [ABSTRACT FROM AUTHOR]

During the recent several decades, lateral flow immunoassay (LFIA) constructed with gold nanoparticle (AuNP) has been widely utilized to conveniently detect target analyte. However, AuNP-based LFIA has limitations, such as limited detection sensitivity and quantification capability. Herein, to overcome these constraints, we have developed cerium oxide nanoparticle (nanoceria)-based LFIA for C-reactive protein (CRP) detection in human serum samples. It was fabricated with nanoceria, a notable nanozyme that shows an oxidase activity to quickly oxidize organic substrate, such as 3,3′,5,5′-tetramethylbenzidine (TMB), to produce colored product without any oxidizing agent (e.g., hydrogen peroxide), which is advantageous for realizing point-of-care testing (POCT) applications. By employing human blood serum spiked with CRP, the nanoceria-based LFIA showed two blue-colored lines on the test and control region within 3 min via TMB oxidation, by the captured nanoceria through antigen–antibody interaction. The produced blue-colored lines were distinguished by naked eyes and quantitated with real images acquired by a conventional smartphone with the ImageJ software. With this strategy, target CRP was specifically determined down to 117 ng mL−1 with high detection precisions yielding coefficient of variation of 9.8–11.3% and recovery of 90.7–103.2% using human blood serum samples. This investigation demonstrates the potential of oxidase-like nanoceria for developing LFIA, which is particularly useful in instrumentation-free POCT environments. [ABSTRACT FROM AUTHOR]

Coronavirus disease (COVID-19) is challenging many health, economic, and social systems. RT-PCR assays are diagnosis gold standard; however, they can lead to false-negative results. Therefore, anti-SARS-CoV-2 IgG, IgM, and IgA investigation can play a complementary role in assessing the individuals immune status. Majority of serological tests focus on IgM and IgG although IgA are the main immunoglobulins involved in mucosal immunity. It has been reported that digestive symptoms may occur in the absence of any typical respiratory symptom. Thus, a complete screening, comprising IgA, IgM, and IgG detection could be more consistent and useful in patients with atypical symptoms or in paucisymptomatic cases. Current literature describes over 200 immunoassays available worldwide, pointing out a great results variability, depending on methodology or antigens' nature. In our study we evaluated anti-SARS-CoV-2 IgA, IgM, and IgG trend on a control group and on two COVID-19 patient groups (early and late infection time) with a lateral-flow combined immunoassay (LFIA) and an enzyme-linked immunosorbent assay (ELISA). Dissimilar antibodies time kinetics have been described in COVID-19 (decreasing IgM concentration with IgA/IgG persistence for a longer time; as well as persistent IgA, IgG, and IgM concentration); our results confirmed both of them depending on the methodology; therefore, it is difficult to compare different studies outcomes, suggesting the importance of a serological tests international standardization. Nevertheless, we propose a flowchart with combined anti-SARS-CoV-2 IgG/IgM/IgA detection as a screening on general population, where serological positivity should be considered as an "alert," to avoid and contain possible new outbreaks. [ABSTRACT FROM AUTHOR]

Pueraria candollei is an ingredient of Thai herbal medicine, dietary supplements, and cosmetics. The in vitro and in vivo studies of this plant supported anti-osteoporotic activity and used for hormone replacement therapy. Deoxymiroestrol shows the most potent phytoconstituent in tuberous root of P. candollei with estrogenic activity. The quality controls are important for good agricultural practice (GAP) and good manufacturing practice (GMP) of plant-derived raw materials. The rapid detection of lateral flow immunoassay (LFIA) using colloidal gold is simply method, easy visualize detection and produce less waste than conventional chromatographic detection. In this study, LFIA for qualitative detection of deoxymiroestrol using antigen-binding fragment antibody (Fab) was developed. The result showed that the developed LFIA displays specific detection of deoxymiroestrol. Cross reactivity of this method was analyzed with miroestrol, isomiroestrol and methylisomiroestrol which showed 39.97%, 7.71% and 5.72%, respectively. After optimal condition, limit of detection (LOD) for deoxymiroestrol is 250 ng/ml. Plant samples were applied to strip test compare with indirect competitive ELISA using polyclonal antibody to confirm the application of LFIA. The results of LFIA method were comparable with those from ELISA. This developed lateral flow immunoassay can apply to detect deoxymiroestrol for the rapid testing. The developed method can use for quality control in plant samples as deoxymiroestrol is biomarker compound in P. candollei. [ABSTRACT FROM AUTHOR]

Staphylococcus aureus (S. aureus) is a prevalent bacterium that affects patient recovery post-surgery and can cause postoperative complications. Consequently, detecting S. aureus in clinical settings is critical for ensuring patient well-being. In our work, a "visual-colorimetric-photothermal" three-in-one multimodal lateral flow immunoassays (LFIA) was developed for S. aureus detection to meet the growing demand for point-of-care testing (POCT) of bacteria in the field. The sensors relied on Pd/Pt@Ab1 NPs nanoprobes, created by decorating the surface of bimetallic nanoprobes (Pd/Pt NPs) with S. aureus antibodies (Ab1). A visual detection mode was realized by the Pd/Pt@Ab1 NPs being captured on the surface of test line (T line) using the sandwich method, offering a limit of detection (LOD) of 103 CFU/mL. Subsequently, Pd/Pt@Ab1 NPs catalyzed the TMB system into oxTMB to achieve colorimetric analysis, covering a detection range from 102 to 107 CFU/mL. Remarkably, the oxTMB exhibited the photothermal conversion efficiency under near-infrared (NIR) light, leading to temperature variations under 808 nm irradiation, correlating with different bacteria concentrations, with an LOD as low as 4 CFU/mL. The methodology enabled quantitative analysis of bacteria in clinical samples with satisfactory results. The diversity, complementarity, and synergy of the integrated output signals in this multimode LFIA improved the flexibility, utility, and accuracy of the assay, performing well as a POCT platform for various application scenarios. • A "three-in-one" multimode lateral flow immunoassay was developed for the detection of Staphylococcus aureus in clinic. • Pd/Pt@Ab1 NPs was synthesized to enhance and improve the sensitivity of bacterial detection. • Oxidized TMB had colorimetric and photothermal properties. • The methodology developed exhibited flexibility, practicality and accuracy. [ABSTRACT FROM AUTHOR]

[Display omitted] • Rapid antibody conjugation strategy via charge inversion achieved expedited binding of antibodies to AuNBPs. • AuNBPs based SERS-LFIA strip for AFP detection with the limit of detection as low as 0.72 pg/mL. • Novel antibody conjugation strategy promotes the utilizing of positively charged nanoparticles in LFIA. Alpha-fetoprotein (AFP) is widely utilized as the primary serum marker for diagnosing Hepatocellular carcinoma. Integrating surface-enhanced Raman scattering (SERS) with lateral flow immunoassays (LFIA) displays significant promise for the rapid quantification of AFP. Gold nanobipyramids (AuNBPs) is a kind of SERS probe with high activity showing strong application potential in SERS-LFIA. However, the drastic electrostatic interaction between negative charged antibodies and positive charged AuNBPs will result in uncontrollable aggregation, which poses a challenge for antibody binding and limits its application in SERS-LFIA. Hence, we propose a rapid antibody conjugation strategy with the aid of instant charge inversion of AuNBPs, which enables efficient and expedited antibody coupling onto AuNBPs. The thiol-free fish sperm (FSDNA) was employed to adsorb on the cetyltrimethylammonium bromide (CTAB) coated AuNBPs for immediate charge inversion. The adsorption of FSDNA will cause partial stripping of CTAB from the AuNBPs surface to provide additional active sites for antibodies binding. In this study, approximately average 37 AFP-antibodies were verified bonding on one charge inverted AuNBPs by direct incubation for 30 min. The antibodies modified AuNBPs were further incubated with 4-nitrothiophenol for preparing SERS immune probes, which display excellent colloid stability and specificity. The probes were used to construct SERS-LFIA strips for AFP detection, enabling highly sensitive detection of AFP with the limit of detection (LOD) as low as 0.72 pg·mL−1. The developed SERS-LFIA strip demonstrates excellent stability and accuracy in detecting serum samples, with a recovery rate ranging from 84 % to 114 %. This rapid antibody coupling strategy is applicable to a wide range of positively charged nanoparticles, effectively addressing the challenging issue of utilizing such nanomaterials in LFIA. [ABSTRACT FROM AUTHOR]

Lateral flow Point-Of-Care Tests (POCTs) are a valuable tool for rapidly detecting pathogens and the associated immune response in humans and animals. In the context of the SARS-CoV-2 pandemic, they offer rapid on-site diagnostics and can relieve centralized laboratory testing sites, thus freeing resources that can be focused on especially vulnerable groups. However, visual interpretation of the POCT test lines is subjective, error prone and only qualitative. Here we present pyPOCQuant, an open-source tool implemented in Python 3 that can robustly and reproducibly analyze POCTs from digital images and return an unbiased and quantitative measurement of the POCT test lines.

Extracellular vesicles (EVs) are biological nanoparticles of great interest as novel sources of biomarkers and as drug delivery systems for personalized therapies. The research in the field and clinical applications require rapid quantification. In this study, we have developed a novel lateral flow immunoassay (LFIA) system based on Fe3O4 nanozymes for extracellular vesicle (EV) detection. Iron oxide superparamagnetic nanoparticles (Fe3O4 MNPs) have been reported as peroxidase-like mimetic systems and competent colorimetric labels. The peroxidase-like capabilities of MNPs coated with fatty acids of different chain lengths (oleic acid, myristic acid, and lauric acid) were evaluated in solution with H2O2 and 3,3,5,5-tetramethylbenzidine (TMB) as well as on strips by biotin–neutravidin affinity assay. As a result, MNPs coated with oleic acid were applied as colorimetric labels and applied to detect plasma-derived EVs in LFIAs via their nanozyme effects. The visual signals of test lines were significantly enhanced, and the limit of detection (LOD) was reduced from 5.73 × 107 EVs/μL to 2.49 × 107 EVs/μL. Our work demonstrated the potential of these MNPs as reporter labels and as nanozyme probes for the development of a simple tool to detect EVs, which have proven to be useful biomarkers in a wide variety of diseases.

Objectives: To examine and summarize the current literature on serologic methods for the detection of antibodies to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2).Methods: A literature review was performed using searches in databases including PubMed, medRxiv, and bioRxiv. Thirty-two peer-reviewed papers and 23 preprints were examined.Results: The studies included lateral flow immunoassay, enzyme-linked immunosorbent assay, chemiluminescence immunoassay, and neutralizing antibody assays. The use of all major SARS-CoV-2 antigens was demonstrated to have diagnostic value. Assays measuring total antibody reactivity had the highest sensitivity. In addition, all the methods provided opportunities to characterize the humoral immune response by isotype. The combined use of IgM and IgG detection resulted in a higher sensitivity than that observed when detecting either isotype alone. Although IgA was rarely studied, it was also demonstrated to be a sensitive marker of infection, and levels correlated with disease severity and neutralizing activity.Conclusions: The use of serologic testing, in conjunction with reverse transcription polymerase chain reaction testing, was demonstrated to significantly increase the sensitivity of detection of patients infected with SARS-CoV-2. There was conflicting evidence regarding whether antibody titers correlated with clinical severity. However, preliminary investigations indicated some immunoassays may be a surrogate for the prediction of neutralizing antibody titers and the selection of recovered patients for convalescent serum donation. [ABSTRACT FROM AUTHOR]

Sulfamethazine (SMZ) as a broad antibiotic is widely used in livestock and poultry. However, the abuse of SMZ in livestock feed can lead to SMZ residues in food and the resistance of bacteria to drugs. Thus, a method for the detection of SMZ in food is urgently needed. In this study, quantum dot (QD) nanobeads (QBs) were synthesized by encapsulating CdSe/ZnS QDs using a microemulsion technique. The prepared QBs as signal probes were applied in lateral flow immunoassay (LFIA) for the detection of SMZ in chicken and milk. Our proposed method had limits of detection of 0.1138–0.0955 ng/mL and corresponding linear ranges of 0.2–12.5, 0.1–15 ng/mL in chicken and milk samples, respectively. The recovery of LFIA for the detection of SMZ was 80.9–109.4% and 84–101.6% in chicken and milk samples, respectively. Overall, the developed QBs-LFIA had high reliability and excellent potential for rapid and sensitive screening of SMZ in food.

In this study, the coupling of magnetic enrichment of bacteria from real samples with rapid surface enhanced Raman spectroscopy (SERS) detection was reported. The selective isolation and enrichment for the model bacteria Escherichia coli (E. coli) was performed using E. coli (primary) antibody bound-magnetic gold (Fe 3 O 4 @Au) nanoparticles. Following isolation and enrichment, the rennet enzyme was used to cleave of casein modified Fe 3 O 4 /Au-PEI nanoparticles from primary antibody-bound bacteria to prevent the nanoparticle aggregation and provide the movement of bacteria on nitrocellulose membrane. In the first part of the study, optimization studies were carried out namely; the amounts of gold nanoparticles (AuNPs), polyethyleneimine coated magnetic gold (Fe 3 O 4 /Au-PEI) nanoparticles, casein and rennet enzyme. The SERS signals of DTNB (5,5′-Dithiobis(2-nitrobenzoic acid)) molecule were collected on the test line and a calibration curve was plotted by using signal intensities. The correlation between the concentration of E. coli and SERS signal was found to be linear within the range of 101–107 cfu/mL (R2 = 0.984, LOD = 0.52 cfu/mL and LOQ = 1.57 cfu/mL). The selectivity of the paper-based lateral flow immunoassay (LFIA) was examined with Bacillus subtilis (B. subtilis), Micrococcus luteus (M. luteus), Salmonella enteritidis (S. enteritidis) which did not produce any significant response compared with E. coli measurement. Finally, the developed paper-based LFIA was tested with urine and milk samples. The obtained SERS results were compared with a plate counting method results which were in a good accordance. The developed method was found as rapid and sensitive to E. coli with a total analysis time of less than 60 min. Image 1 • Paper-based strips were developed using the magnetic enrichment. • LFIA strips were performed using rennet enzyme isolation of E. coli from buffer and real media. • The selectivity tests of LFIA were obtained with milk and urine media. • The specificity tests of LFIA were evaluated with B. subtilis , M. luteus , S. enteritidis. [ABSTRACT FROM AUTHOR]

Rapid and sensitive diagnosis of influenza is urgently needed to address the limitations of low sensitivity associated with current rapid tests available for clinics and on‐site monitoring. A novel horseradish peroxidase (HRP)‐labeled lateral flow immunoassay strip (HRP‐LFIA) for rapid simultaneous detection and differentiation of influenza A (INF A) and influenza B (INF B) viruses were developed. This immunoassay was based on the signal amplification by the HRP‐catalyzed oxidation of 3, 3′, 5, 5′‐tetramethylbenzidine forming a colored insoluble product, which was proportional to the analyte concentration. Compared with conventional gold‐colloidal based strips, an analytical sensitivity enhancement of more than one order of magnitude for thirteen INF virus isolates was observed. A total of 1487 swabs obtained from persons with influenza‐like illnesses were tested for the presence of INF A and B viruses using real‐time reverse transcription polymerase chain reaction (rRT‐PCR) as the reference criterion. The overall sensitivities of HRP‐LFIA were 77.5% (100/129) and 71.2% (116/163) for INF A and INF B, respectively. The overall specificities were 99.8% (1144/1146) and 99.8% (918/920), respectively. The nasopharyngeal sampling method yielded higher sensitivity rates of 90.2% (55/61) and 82.6% (71/86). In conclusion, this user‐friendly assay could be a promising rapid detection method for rapid screening of INF A and INF B viruses. A novel immunoassay based on the signal amplification by the HRP‐catalyzed oxidation of 3, 3', 5, 5'‐tetramethylbenzidine was established. Compared with conventional gold based strips, an analytical sensitivity enhancement of more than one order of magnitude was observed. [ABSTRACT FROM AUTHOR]

Extracellular protein kinase A autoantibody (ECPKA-AutoAb) has been suggested as a universal cancer biomarker due to its higher amounts in serum of several types of cancer patients than that of normal individuals. Herein, we first developed a lateral flow immunoassay (LFIA) tool, using a sandwich format, toward ECPKA-AutoAb in human serum. For this format, 3G2 as a capture antibody was identified using hybridoma technique and a series of screenings where it showed superior capacity to recognize Enzo PKA catalytic subunit alpha (Cα), compared to other PKA antibodies and antigens. Using these components, we performed sandwich ELISA toward a mimic and real sample of ECPKA-AutoAb. As per the results, limit of detection (LOD) was found to be 135 ng/mL and ECPKA-AutoAb levels were higher in various cancer patients than in normal individuals like previous studies. Based on these results, we applied this sandwich format into LFIA tool and found that the LOD of the fabricated LFIA tool showed about 3.8 ng/mL using spiked PKA-Ab, which is significantly improved compared to the LOD of sandwich ELISA. Also, the developed LFIA tool demonstrated a remarkable ability to detect significant differences in ECPKA-AutoAb levels between normal and cancer patients within 15 min, showing a potential for point-of-care (PoC) detection. One interesting point is that our LFIA strip contains an additional conjugation pad II, named because of its position behind the conjugation pad, in which PKA Cα is dried, enabling a sandwich format. • Development of a sandwich format-based LFIA tool toward ECPKA-autoantibody. • 3G2, a new PKA antibody, is identified as a capture antibody in LFIA tool. • Enzo PKA catalytic subunit alpha (Cα) is discovered as linker antigen in LFIA tool. • The developed LFIA tool reveals a limit of detection of 3.8 ng/mL. [ABSTRACT FROM AUTHOR]

Dengue is one of the most widespread and fatal arboviral infections in the world. Early detection of dengue virus (DENV) is essential to prevent the spread of the disease and provide an immediate response. The lateral flow immunoassay (LFIA) systems are low-cost, rapid, sensitive, targeted, and straightforward detection, which is an ideal early detection candidate for point-of-care testing (POCT) in dengue-affected areas. However, current commercial LFIA kits cannot fully satisfy the sensitivity, specificity, serotype differentiation, and multiplex detection requirements. Therefore, various strategies have been applied to optimize the LFIA for DENV detection, including label material improvement, optical enhancement and novel structure design. In this review, we comprehensively presented the snapshot of dengue, the principle of LFIA, and recent progress in the LFIA optimization for dengue diagnoses. Furthermore, this review also discusses insights into the prospect of LFIA dengue diagnostic methods, such as microfluidics, multiplex design, nucleic acid-typed probes and smartphone-assisted result analysis. [Display omitted] • The snapshot of dengue and the principle of lateral flow immunoassay (LFIA) have been introduced. • The latest LFIA progress for dengue diagnoses has been classified and presented in detail. • The challenges and future directions of LFIA dengue diagnosis methods have been discussed. [ABSTRACT FROM AUTHOR]

Point-of-care testing (POCT) is essential for providing a rapid diagnostic result in a prompt on-site diagnosis and treatment. A quick analysis time and a high sensitivity, with a sample-to-answer format, are the most important features for current POCT diagnostic systems. This review covers recent advances in POCT technologies with an emphasis on demonstrated and commercially available POCT diagnostic systems with laboratory quality using lateral flow immunoassay (LFIA). The system includes the integration of nanoparticles (NPs) in lateral flow test strips (LFTSs) and the mechanism through which particles improve the analytical performance of the fabricated strips. Several examples of NP-based LFTSs were selected to illustrate novel concepts or devices with promising applications as screening tools and superior alternatives to existing conventional strategies in clinical analysis, food safety, and environmental monitoring. In each analyte category, detection methods, configuration of LFIA modules, and advantages of POCT systems are reviewed and discussed along with future prospects. This review also discusses novel signal-enhancement strategies, optimal reader systems, and multiplex design prototypes, which have been employed for highly sensitive multiplex assay of LFTSs.

There have been tremendous advances in in vitro diagnostic (IVD) assays for coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The main IVD assays used for COVID-19 employ real-time reverse transcriptase polymerase chain reaction (RT-PCR) that takes a few hours. But the assay duration has been shortened to 45 min by Cepheid. Of interest is the point-of-care (POC) molecular assay by Abbott that decreased the assay duration to just 5 min. Most molecular tests have been approved by the United States Food and Drug Administration (FDA) under emergency use authorization (EUA) and are Conformité Européenne (CE) marked. A wide range of serology immunoassays (IAs) have also been developed that complement the molecular assays for the diagnosis of COVID-19. The most prominent IAs are automated chemiluminescent IA (CLIA), manual ELISA, and rapid lateral flow IA (LFIA), which detect the immunoglobulin M (IgM) and immunoglobulin G (IgG) produced in persons in response to SARS-CoV-2 infection. The ongoing research efforts and advances in complementary technologies will pave the way to new POC IVD assays in the coming months. However, the performance of IVD assays needs to be critically evaluated before they are employed for the clinical diagnosis of COVID-19.

Lateral Flow Immunoassay (LFIA) strips are among the most widely-used and cost-effective biodetection tools that have applications in disease diagnosis and food safety monitoring. In this paper, we demonstrate the novel application of Thermophotonic Lock-In Imaging (TPLI) in quantitative and sensitive interpretation of LFIA strip results used to detect the pregnancy hormone human chorionic gonadotropin ( hCG ) as a proof-of-concept analyte. Existing optical immunoassay readers, based on image acquisition and processing algorithms, rely on reflective signals (color intensity) emanating from the surface of the LFIA. Such contrast mechanism results in missing a large amount of signal from gold nanoparticles (GNP) trapped inside the bulk of the LFIA nitrocellulose strips and leads to suboptimal detection thresholds and sensitivities. TPLI, on the other hand, operates based on diffusion of thermal waves and as such does not require optical transparency to reach GNPs in the bulk of the strip. Our experimental results indicate that the developed TPLI system is able to detect GNP- hCG conjugates at concentrations as low as 0.2  mIU , while the detection threshold of human visual inspection and commercial optical immunoassay readers were both found to be 2  mIU . Miniaturization of TPLI technique will enable a highly sensitive, quantitative, low-cost, and truly point-of-care total analysis test interpretation system for LFIAs, facilitating critical early stage detection of diseases or biochemical conditions. [ABSTRACT FROM AUTHOR]

Vaccination is an effective strategy to fight COVID-19. However, the effectiveness of the vaccine varies among different populations in varying immune effects. Neutralizing antibody (NAb) level is an important indicator to evaluate the protective effect of immune response after vaccination. Lateral flow immunoassay (LFIA) is a rapid, safe and sensitivity detection method, which has great potential in the detection of SARS-CoV-2 NAb. In this study, a fluorescent beads-based lateral flow immunoassay (FBs-LFIA) and a latex beads-based LFIA (LBs-LFIA) using double antigen sandwich (DAS) strategy were established to detect NAbs in the serum of vaccinated people. The limit of detection (LoD) of the FBs-LFIA was 1.13 ng mL− 1 and the LBs-LFIA was 7.11 ng mL− 1. The two LFIAs were no cross-reactive with sera infected by other pathogenic bacteria. Furthermore, the two LFIAs showed a good performance in testing clinical samples. The sensitivity of FBs-LFIA and LBs-LFIA were 97.44% (95%CI: 93.15%–99.18%) and 98.29% (95%CI: 95.84%–99.37%), and the specificity were 98.28% (95%CI: 95.37%–99.45%) and 97.70% (95%CI: 94.82%–99.06%) compared with the conventional virus neutralization test (cVNT), respectively. Notably, the LBs-LFIA was also suitable for whole blood sample, requiring only 3 μL of whole blood, which provided the possibility to detect NAbs at home. To sum up, the two LFIAs based on double antigen sandwich established by us can rapidly, safely, sensitively and accurately detect SARS-CoV-2 NAb in human serum. [Display omitted] • LFIAs based on double antigen sandwich (DAS) have high sensitivity and specificity compared with cVNT. • The FBs-LFIA achieves a sensitivity of 97.44% and specificity of 98.28% in testing clinical serum samples (n = 389). • The LBs-LFIA achieves a sensitivity of 98.29% and a specificity of 97.70% in testing clinical serum samples (n = 554). • The LBs-LFIA can be used to plasma, serum and whole blood samples so it's suitable for home self-test and community hospital. [ABSTRACT FROM AUTHOR]

Foodborne pathogens cause diseases in humans. The traditional methods of detecting foodborne pathogens are time-consuming. The lateral flow immunoassay (LFIA) has become a widely used detection platform for onsite testing of various foodborne pathogens due to its time-efficiency, cost-effectiveness, portability, and ease of use. With the development of novel nanomaterials, the sensitivity of the LFIA has improved tremendously compared with traditional colorimetric LFIA sensors. This review first summarizes the principles and corresponding formats of the LFIA. Then, a detailed classification of nanomaterial label (e.g., metallic, carbon and selenium, fluorescent, and magnetic nanoparticles) synthesis, signal amplification strategy, and detection principles are discussed as related to food safety. Subsequently, the LFIA used in the detection of pathogenic bacteria, including Escherichia coli, Vibrio parahaemolyticus, Staphylococcus aureus, Listeria monocytogenes, and Salmonella, are classified and summarized. Multiple signal modes have been explored that improve the sensitivity of foodborne pathogen detection. Further improvement should focus on the design and preparation of high signal-to-noise ratio nanomaterials to achieve highly sensitive detection, and multitarget and multimode sensing. [ABSTRACT FROM AUTHOR]

Shiga toxin-producing Escherichia coli O157:H7 (STEC) cause food-borne illness that may be fatal. STEC strains enumerate two types of potent Shiga toxins (Stx1 and Stx2) that are responsible for causing diseases. It is important to detect the E. coli O157 and Shiga toxins in food to prevent outbreak of diseases. We describe the development of two multi-analyte antibody-based lateral flow immunoassays (LFIA); one for the detection of Stx1 and Stx2 and one for the detection of E. coli O157 that may be used simultaneously to detect pathogenic E. coli O157:H7. The LFIA strips were developed by conjugating nano colloidal gold particles with monoclonal antibodies against Stx1 and Stx2 and anti-lipid A antibodies to capture Shiga toxins and O157 antigen, respectively. Our results indicate that the LFIA for Stx is highly specific and detected Stx1 and Stx2 within three hours of induction of STEC with ciprofloxacin at 37 °C. The limit of detection for E. coli O157 LFIA was found to be 105 CFU/mL in ground beef spiked with the pathogen. The LFIAs are rapid, accurate and easy to use and do not require sophisticated equipment or trained personnel. Following the assay, colored bands on the membrane develop for end-point detection. The LFIAs may be used for screening STEC in food and the environment. [ABSTRACT FROM AUTHOR]

Parathyroid hormone-like hormone (PTHLH) exerts relevant roles in progression and dissemination of several tumors. However, factors influencing its production and secretion have not been fully characterized. The main limitation is the lack of specific, sensitive and widely available techniques to detect and quantify PTHLH. We have developed a lateral flow immunoassay using gold nanoparticles label for the fast and easy detection of PTHLH in lysates and culture media of three human cell lines (HaCaT, LA-N-1, SK-N-AS). Levels in culture media and lysates ranged from 11 to 20 ng/mL and 0.66 to 0.87 μg/mL respectively. Results for HaCaT are in agreement to the previously reported, whereas LA-N-1 and SK-N-AS have been evaluated for the first time. The system also exhibits good performance in human serum samples. This methodology represents a helpful tool for future in vitro and in vivo studies of mechanisms involved in PTHLH production as well as for diagnostics. From the Clinical Editor Parathyroid Hormone-like Hormone (PTHLH) is known to be secreted by some tumors. However, the detection of this peptide remains difficult. The authors here described their technique of using gold nanoparticles as label for the detection of PTHLH by Lateral-flow immunoassays (LFIAs). The positive results may also point a way to using the same technique for the rapid determination of other relevant cancer proteins. [ABSTRACT FROM AUTHOR]

A lateral flow immunoassay (LFIA) has been developed and fully validated to detect the primary amnesic shellfish poisoning (ASP) toxin, domoic acid (DA). The performance characteristics of two versions of the test were investigated using spiked and naturally contaminated shellfish (mussels, scallops, oysters, clams, and cockles). The tests provide a qualitative result, to indicate the absence or presence of DA in extracts of shellfish tissues, at concentrations that are relevant to regulatory limits. The new rapid assay (LFIA version 2) was designed to overcome the performance limitations identified in the first version of the assay. The improved test uses an electronic reader to remove the subjective nature of the generated results, and the positive cut-off for screening of DA in shellfish was increased from 10ppm (version 1) to 17.5ppm (version 2). A simple extraction and test procedure was employed, which required minimal equipment and materials; results were available 15min after sample preparation. Stability of the aqueous extracts at room temperature (22°C) at four time points (up to 245min after extraction) and across a range of DA concentrations was 100.3±1.3% and 98.8±2.4% for pre- and post-buffered extracts, respectively. The assay can be used both within laboratory settings and in remote locations. The accuracy of the new assay, to indicate negative results at or below 10ppm DA, and positive results at or above 17.5ppm, was 99.5% (n=216 tests). Validation data were obtained from a 2-day, randomised, blind study consisting of multiple LFIA lots (n=3), readers (n=3) and operators (n=3), carrying out multiple extractions of mussel tissue (n=3) at each concentration (0, 10, 17.5, and 20ppm). No matrix effects were observed on the performance of the assay with different species (mussels, scallops, oysters, clams, and cockles). There was no impact on accuracy or interference from other phycotoxins, glutamic acid or glutamine with various strip incubations (8, 10, and 12min). The accuracy of the assay, using naturally contaminated samples to indicate negative results at or below 12.5ppm and positive results at or above 17.5ppm, was 100%. Variability between three LFIA lots across a range of DA concentrations, expressed as coefficient of variation (% CV), was 1.1±0.4% (n=2 days) based on quantitative readings from the electronic reader. During an 8 week stability study, accuracy of the method with test strips stored at various temperatures (6, 22, 37 and 50°C) was 100%. Validation for both versions included comparisons with results obtained using reference LC–UV methods. [ABSTRACT FROM AUTHOR]

Abstract: Helicobacter pylori infection is the most common human infection where approximately 50% of the world populations are infected. The diagnosis of such infection is mainly done by endoscopy where gastric biopsies are examined for the presence of H. pylori. Such invasive approach is costly, time consuming and generally requires more than one test to confirm the infection. Serology on the other hand is a non-invasive approach that can detect H. pylori exposure. The lateral flow immunoassays (LFIA) support the serological approach and have the advantage of being fast, economic and require no additional equipment or experience. In this review the principles, components of the LFIA, sensitivities and specificities of the commercially available H. pylori test strips were compared and discussed. [Copyright &y& Elsevier]

In this paper, the particle filtering approach is used, together with the kernel smoothing method, to identify the state-space model for the lateral flow immunoassay through available but short time-series measurement. The lateral flow immunoassay model is viewed as a nonlinear dynamic stochastic model consisting of the equations for the biochemical reaction system as well as the measurement output. The renowned extended Kalman filter is chosen as the importance density of the particle filter for the purpose of modeling the nonlinear lateral flow immunoassay. By using the developed particle filter, both the states and parameters of the nonlinear state-space model can be identified simultaneously. The identified model is of fundamental significance for the development of lateral flow immunoassay quantification. It is shown that the proposed particle filtering approach works well for modeling the lateral flow immunoassay. [ABSTRACT FROM PUBLISHER]

• A neotype magnetic flux sensor for application in immunomagnetic biosensing platforms was designed. • The mathematical model and computer simulation method were used to optimize parameters of the sensor. • The modified spiral rectangular coils improves the intensity of response. • Sensitivity when applied a differential configuration strategy for sensor pick-up coils to assess MNPs influence. [Display omitted] In recent years, point-of-care testing (POCT) has become a topical issue. Lateral flow immunoassay strategies based on magnetic nanoparticles (MNPs) are important POCT elements due to their sensitive quantification of biological materials via MNP magnetic field measurement. In this study, we designed a magnetic flux sensor for use in immunomagnetic biosensing platforms, incorporating a mathematical model and computer simulation strategy. The system used field programmable gate array (FPGA) as the control chip, synthesized excitation signals and excited coils to generate excitation magnetic fields. Also, the stepping motor was controlled to drive the test strip at a uniform speed through the sensor detection area. A differential configuration strategy was used for sensor pick-up coils to assess MNP influence on the magnetic flux, which was insensitive to background magnetic interference and common-mode noise. These factors significantly enhanced the signal-to-noise ratio of the sensor. The magnetic flux sensor structure was optimized, and response magnetic field characteristics of MNP on test strips analyzed using finite element analysis (FEA) simulations. System performance was evaluated by testing human chorionic gonadotropin (HCG) and gastrin-17 (G17), which demonstrated a linear performance, with a limit of detection of 0.0098 mIU/mL and 9.1016 pg/mL, respectively. This system may be used to identify other target analytes in different application settings. [ABSTRACT FROM AUTHOR]

Sulfamethazine (SMZ) as a broad antibiotic is widely used in livestock and poultry. However, the abuse of SMZ in livestock feed can lead to SMZ residues in food and the resistance of bacteria to drugs. Thus, a method for the detection of SMZ in food is urgently needed. In this study, quantum dot (QD) nanobeads (QBs) were synthesized by encapsulating CdSe/ZnS QDs using a microemulsion technique. The prepared QBs as signal probes were applied in lateral flow immunoassay (LFIA) for the detection of SMZ in chicken and milk. Our proposed method had limits of detection of 0.1138–0.0955 ng/mL and corresponding linear ranges of 0.2–12.5, 0.1–15 ng/mL in chicken and milk samples, respectively. The recovery of LFIA for the detection of SMZ was 80.9–109.4% and 84–101.6% in chicken and milk samples, respectively. Overall, the developed QBs-LFIA had high reliability and excellent potential for rapid and sensitive screening of SMZ in food. [ABSTRACT FROM AUTHOR]

• Monoclonal antibodies for sensitive and selective gluten detection. • Rapid gluten detection (<5 min) by lateral flow immunoassay. • A single-use biosensor for easy gluten testing of foods. The gluten protein found in a variety of cereal grains is a food allergen that can elicit a spectrum of immuno-inflammatory responses in people. Consumer awareness has prompted changes in food labeling requirements, expanded gluten-free food product availability and increased demand for effective gluten testing methodologies. To meet the challenges associated with gluten testing from diverse and complex foods we developed a lateral flow immunoassay (LFIA) using a pair of novel gliadin monoclonal antibodies (MAbs). Using a visual gold reporter, we show sensitive gluten detection (150 ng/mL) from complex food substrates using a fast (<5 min) and easy testing methodology. In this report we characterize the binding properties of a cohort of newly generated gliadin monoclonal antibodies suitable for gluten detection using multiple assay formats and introduce a novel plug- n -play test strip platform with integrated test components in a single-use format. [ABSTRACT FROM AUTHOR]

The coronavirus infection 2019 (COVID-19) pandemic, caused by the highly contagious SARS-CoV-2 virus, has provoked a global healthcare and economic crisis. The control over the spread of the disease requires an efficient and scalable laboratory-based strategy for testing the population based on multiple platforms to provide rapid and accurate diagnosis. With the onset of the pandemic, the reverse transcription polymerase chain reaction (RT-PCR) method has become a standard diagnostic tool, which has received wide clinical use. In large-scale and repeated examinations, these tests can identify infected patients with COVID-19, with their accuracy, however, dependent on many factors, while the entire process takes up to 6–8 h. Here we also describe a number of serological systems for detecting antibodies against SARS-CoV-2. These are used to assess the level of population immunity in various categories of people, as well as for retrospective diagnosis of asymptomatic and mild COVID-19 in patients. However, the widespread use of traditional diagnostic tools in the context of the rapid spread of COVID-19 is hampered by a number of limitations. Therefore, the sharp increase in the number of patients with COVID-19 necessitates creation of new rapid, inexpensive, sensitive, and specific tests. In this regard, we focus on new laboratory technologies such as loop mediated isothermal amplification (LAMP) and lateral flow immunoassay (LFIA), which have proven to work well in the COVID-19 diagnostics and can become a worthy alternative to traditional laboratory-based diagnostics resources. To cope with the COVID-19 pandemic, the healthcare system requires a combination of various types of laboratory diagnostic testing techniques, whodse sensitivity and specificity increases with the progress in the SARS-CoV-2 research. The testing strategy should be designed in such a way to provide, depending on the timing of examination and the severity of the infection in patients, large-scale and repeated examinations based on the principle: screening–monitoring–control. The search and development of new methods for rapid diagnostics of COVID-19 in laboratory, based on new analytical platforms, is still a highly important and urgent healthcare issue. In the final part of the review, special emphasis is made on the relevance of the concept of personalized medicine to combat the COVID-19 pandemic in the light of the recent studies carried out to identify the causes of variation in individual susceptibility to SARS-CoV-2 and increase the efficiency and cost-effectiveness of treatment. [ABSTRACT FROM AUTHOR]

• The U-Net, a variant of the deep learning method, is used to automatically detect the concentration of LFIA images. • The method exhibits higher robustness than traditional approaches, evaluation index including PSNR and IOU. • Excellent segmentation results based on different concentrations and detections. Lateral flow immunoassay (LFIA) is one of the most common methods in point-of-care testing, which is widely applied in some conditions for various applications. Image segmentation is an increasingly popular experimental paradigm to efficiently test the target area in LFIA. However, due to process pollution, and problems related to the experimental operation and irregular structure of the background of the reaction, currently available tools cannot be used to extract correct signals from these images, which affects the accuracy of detection. Machine learning has significantly improved modern biochemical analysis by pushing the limits of traditional techniques for the recognition and processing of images. In this paper, the U-Net, a variant of the convolutional neural network (CNN) is used for the quantitative analysis of LFIA images for the accurate quantification of single- and multi-target images. By graying, binarizing, and labeling different concentrations of test strips, the target area of LFIA images containing the T-/C-lines is extracted and obtained. Then it provides updated trends and directions for the development of LFIA technology. Several indicators are introduced to evaluate the proposed U-Net structure to verify the feasibility and effectiveness of its image processing capability. When the trained U-Net model was used to process images, the peak signal-to-noise ratio was 22.4 dB, significantly higher than prevalent methods in the area that have reported only a 4 dB improvement in the quality of the graphics. The intersection-over-union between samples also increased to above 93%. Our results show that the proposed method has significant potential for detecting a segmented target in an LFIA area, especially weak positive signals and multichannel detection. With other modifications, this deep learning method can be applied as a powerful tool to study rapid detection devices, systems, and biological images. Image, graphical abstract [ABSTRACT FROM AUTHOR]

There have been tremendous advances in in vitro diagnostic (IVD) assays for coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The main IVD assays used for COVID-19 employ real-time reverse transcriptase polymerase chain reaction (RT-PCR) that takes a few hours. But the assay duration has been shortened to 45 min by Cepheid. Of interest is the point-of-care (POC) molecular assay by Abbott that decreased the assay duration to just 5 min. Most molecular tests have been approved by the United States Food and Drug Administration (FDA) under emergency use authorization (EUA) and are Conformité Européenne (CE) marked. A wide range of serology immunoassays (IAs) have also been developed that complement the molecular assays for the diagnosis of COVID-19. The most prominent IAs are automated chemiluminescent IA (CLIA), manual ELISA, and rapid lateral flow IA (LFIA), which detect the immunoglobulin M (IgM) and immunoglobulin G (IgG) produced in persons in response to SARS-CoV-2 infection. The ongoing research efforts and advances in complementary technologies will pave the way to new POC IVD assays in the coming months. However, the performance of IVD assays needs to be critically evaluated before they are employed for the clinical diagnosis of COVID-19. [ABSTRACT FROM AUTHOR]

Immunoassay has been routinely used in hospitals and central labs. Nowadays, to further meet the requirement of widespread applications of immunoassays, it is urgently needed to produce a simplified, rapid and low-cost immunoassay to perform tests on site. To this end, paper-based point-of-care (POC) immunoassays have attracted intensive interests in recent years. In this paper, we present a comprehensive review of the recent advances and emerging trends of paper-based POC immunoassays, including the fundamental components and work principles, various detection mechanisms and applications, and existing commercialized devices/products. At last, we envision three promising development directions for paper-based POC immunoassays. [ABSTRACT FROM AUTHOR]