Lateral Flow Immunochromatographic Assay Research Articles

Lateral Flow Immunochromatography Assay for Detection of Furosemide in Slimming Health Foods.

In recent years, furosemide has been found to be abused in slimming health foods. There is an urgent need for a simpler, faster method for detecting furosemide in slimming health foods. In this study, a rapid, convenient and sensitive lateral flow immunochromatography (LFIA) based on Au nanoparticles (AuNPs) was established for the first time. Under optimal conditions, the qualitative limit of detection (LOD) of the AuNPs-based LFIA was 1.0~1.2 μg/g in slimming health foods with different substrates. AuNPs-LFIA could specifically detect furosemide within 12 min (including sample pretreatment) and be read by the naked eye. The developed AuNPs-LFIA showed high consistency with liquid chromatography with tandem mass spectrometry (LC-MS/MS), and no false positive or false negative results were found in spiked slimming health foods, proving that the AuNPs-LFIA should be accurate and reliable. The AuNPs-LFIA reported here provides a serviceable analytical tool for the on-site detection and rapid initial screening of furosemide for the first time.

A magnetic nanoparticle-based lateral flow immunochromatography assay for the rapid detection of fluoroquinolones in milk

A magnetic nanoparticle-based lateral flow immunochromatography assay for the rapid detection of fluoroquinolones in milk

Red Zn2SiO4:Eu3+ and Mg2TiO4:Mn4+ nanophosphors for on-site rapid optical detections: Synthesis and characterization.

This study reports the synthesis and characterization of the red nanophosphors Zn2SiO4:Eu3+ (ZSO:Eu3+) and Mg2TiO4:Mn4+ (MTO:Mn4+). The use of phosphors as a fluorescence label for lateral flow immunochromatographic assay (LFIA) has also been described. The optimal photoluminescence (PL) for ZSO:Eu3+ was obtained when it was synthesized with 7 mol% of Eu3+ and annealed at 1100 °C for 1 h. Long fluorescence lifetime (1.01 ms), high activation energy it {text{E}}_{text{a}} (0.28 eV), and low PL degeneration (10% at 110 °C) are the characteristics of ZSO:Eu3+. MTO:Mn4+ also exhibited high PL intensity along with a high Ea of 0.32 eV. The emission wavelengths of phosphors are biocompatible with the optical bio-window of tissues. When human immunoglobulin G (human IgG) at a constant concentration of 100 μg/mL was used for detection, the PL ratios of the test line to the control line were 2.15 and 2.28 for the ZSO:Eu3+- and MTO:Mn4+-labeled LFIA, respectively. Thus, the ZSO:Eu3+ and MTO:Mn4+ nanophosphors are capable of human IgG recognition and are the promising candidates as fluorescent labels for on-site rapid optical biodetection.Graphical abstract Supplementary InformationThe online version contains supplementary material available at 10.1007/s00339-021-04733-0.

Highly Specific and Sensitive Detection of Yersinia pestis by Portable Cas12a-UPTLFA Platform.

The recent discovery of collateral cleavage activity of class-II clustered regularly interspaced short palindromic repeats–CRISPR-associated protein (CRISPR-Cas) makes CRISPR-based diagnosis a potential high-accuracy nucleic acid detection method. Colloidal gold-based lateral flow immunochromatographic assay (LFA), which has been combined with CRISPR/Cas-based nucleic detection, usually associates with drawbacks of relative high background and the subjectivity in naked-eye read-out of the results. Here, we developed a novel system composed of Cas12a-based nucleic acid detection and up-converting phosphor technology (UPT)-based LFA (UPT–LFA), termed Cas12a-UPTLFA. We further demonstrated the utility of this platform in highly sensitive and specific detection of Yersinia pestis, the causative agent of the deadly plague. Due to high infectivity and mortality, as well as the potential to be misused as bioterrorism agent, a culture-free, ultrasensitive, specific, and rapid detection method for Y. pestis has long been desired. By incorporating isothermal recombinase polymerase amplification, the Cas12a-UPTLFA we established can successfully detect genomic DNA of Y. pestis as low as 3 attomolar (aM) and exhibited high sensitivity (93.75%) and specificity (90.63%) for detection of spiked blood samples with a detection limit of 102 colony-forming unit per 100 μl of mouse blood. With a portable biosensor, Cas12a-UPTLFA assay can be operated easily by non-professional personnel. Taken together, we have developed a novel Cas12a-UPTLFA platform for rapid detection of Y. pestis with high sensitivity and specificity, which is portable, not expensive, and easy to operate as a point-of-care method. This detection system can easily be extended to detect other pathogens and holds great promise for on-site detection of emerging infectious pathogens.

Development and characterization of mouse monoclonal antibodies targeting to distinct epitopes of Zika virus envelope protein for specific detection of Zika virus.

The recent Zika virus (ZIKV) epidemic poses a serious threat to global health due to its association with microcephaly and congenital diseases in newborns and neurological complications and Guillain-Barré syndrome in adults. However, the majority of people infected with ZIKV do not develop symptoms. The platforms aimed to specifically diagnose ZIKV infection are needed for patient care and public health surveillance. In the study, four ZIKV envelope (E) protein-specific monoclonal antibodies (mAbs) (A1, B1, C1, and 9E-1) have been developed by using the conventional mAb technology. The binding epitopes of mAbs A1, B1, C1, and 9E-1 are located at E(238-257), E(410-431), E(258-277), and E(340-356), respectively. mAb 9E-1 performs 1.4- to 47-fold strong affinity to ZIKV E protein compared to another three mAbs. mAbs A1, C1, and 9E-1 do not have cross-reactivity against the recombinant E proteins of dengue virus serotypes 2, 3, and 4. Although these four mAbs do not have ZIKV neutralizing activity, mAbs B1 and 9E-1 have been developed as the lateral flow immunochromatographic assay for specific detection of ZIKV E protein and virions.Key points• The mAbs targeting to the regions of E(238-257), E(410-431), E(258-277), and E(340-356) do not have ZIKV neutralizing activity.• The binding epitope of mAb 9E-1 is highly specific to ZIKV E protein.• mAbs B1 and 9E-1 can bind to ZIKV virions and have been developed as the lateral flow immunochromatographic assay.

Clinical Performance of Two Methods for Detecting Anti SARS-CoV-2 Antibodies

Evaluating the clinical performance of available methods to detect antibodies against Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2) has become a primordial issue in clinical laboratories. The aim of this study was to evaluate the clinical performance of two methods for SARS-CoV-2 antibodies detection, an automated Chemiluminescent Immunoassay (CLIA) and an immunochromatographic Lateral-Flow Assay (LFA) in patients with positive reverse transcription polymerase chain reaction (RT-PCR). Performance for CLIA method was Positive Agreement (PA) 56.6% and Negative Agreement (NA) 96,6% for IgM and PA 85.8%/NA 90,2% for IgG. Performance for LFA method was PA 56.2% and NA 100% for IgM and PA 95.5% and NA 100 % for IgG. LFA general agreement IgG was better than CLIA. In both methods, significant differences in Kappa index are observed when IgG and IgM are compared. When evaluating the data from a clinical perspective, we found that both method performance for IgM detection may not meet the expected requirements for their clinical utility and could lead to an inappropriate medical decision. The findings of this study show that both immunoassay methods might be reliable for assessing immunological response in COVID-19 patients. Our results also confirm that IgG measurement could be helpful, especially for epidemiological studies in our population. These results provide evidence to justify epidemiological studies in our population.

Rapid quantitative detection for multiple antibiotics in honey using a quantum dot microsphere immunochromatographic strip

We design a honey antibiotic detection system (HADS), which provides honey antibiotic residue rapid on-site detecting solution relying on simple sample preparation tactics, lateral-flow immunochromatographic assay (LFIA)-based strip and handheld sensor reader. Relying on the quantum dot microsphere probes conjugated to the antibiotic monoclonal antibodies, the LFIA strip can simultaneously detect sulfonamides (SAs) and tetracyclines (TCs) in high sensitivity with extremely low detecting limits of 0.4 μg/kg and good specificity. Moreover, the fabricated LFIA strips can be well conserved in vacuum-sealed bags at 4 °C for at least 6 months. Combining with the handheld sensor reader, both SAs and TCs can be quantitatively and automatically measured in high accuracy. All the operations including sample preparation and detection can be finished within 20 min at room temperature on site without any extra devices or complicated operations. • We design honey antibiotic detection system (HADS) for antibiotic residue detection. • HADS can detect sulfonamides (SAs) and tetracyclines (TCs) in high sensitivity. • HADS supports rapid (20 min) and cost-effective (75 cents) antibiotic detection. • HADS is proved with high accuracy, good stability, selectivity and specificity. • HADS supports rapid on-site detection for honey antibiotic residues.

Lateral flow immunoassay for the simultaneous detection of fipronil and its metabolites in food samples

We developed a sensitive and rapid lateral flow immunochromatographic (LFI) assay for the simultaneous detection of fipronil and its metabolites in eggs and cucumbers using gold nanoparticle (GNP)-labeled monoclonal antibodies (mAbs). Anti-fipronil mAbs (1B6) were produced using two haptens and identified by heterologous indirect competitive enzyme-linked immunosorbent assay (icELISA) with half maximal inhibitory concentration (IC50) and limit of detection (LOD) values of 0.46 ± 0.07 and 0.05 ± 0.01 ng mL−1, respectively. The developed LFI strip showed high sensitivity and specificity in the detection of fipronil with cut-off and visual limit of detection (vLOD) values of 10 and 0.25 ng mL−1, respectively. Furthermore, the application of LFI in the detection of fipronil-spiked egg and cucumber samples was validated by liquid chromatography tandem mass spectrometry (LC-MS/MS). Our developed LFI assay is suitable for detection of fipronil and its metabolites in real samples.

Validation of a lateral flow immunochromatographic assay for tinea unguium diagnosis.

Tinea unguium is a common nail disease caused by dermatophytes. Although direct potassium hydroxide (KOH) microscopy and fungal culture are considered the gold standard for diagnosing this disease, their accuracy is insufficient. A lateral flow immunochromatographic assay (LFIA) kit, using a monoclonal antibody against Trichophyton rubrum, was developed and its sensitivity was recently improved 50% in vitro relative to its earlier version. The present study aimed to validate the clinical utility of this improved LFIA kit for diagnosing tinea unguium in comparison with direct KOH microscopy. A similar trial was simultaneously performed using scale samples from patients with tinea pedis to determine the assay's diagnostic potential. Nail samples, approximately 2mg in weight, were collected from 112 non-treated tinea unguium patients and 56 non-tinea unguium patients. Samples from 25 tinea pedis patients and 20 non-tinea pedis patients were also collected. The sensitivity and specificity of the LFIA kit for tinea unguium was 84.8% (95/112) (95% confidence interval [CI], 76.8-90.9) and 83.9% (47/56) (95% CI, 71.7-92.4), respectively. The inconsistency rate was 15.5% (26/168) (95% CI, 10.4-21.9). The sensitivity and specificity of the LFIA kit for tinea pedis was 84.0% (21/25) and 100.0% (20/20), respectively. These results suggest that for diagnosing tinea unguium, the LFIA kit is a useful supplement to, but not a replacement for, direct KOH microscopy. For definitive diagnosis of suspected cases, appropriate sampling, repeated examinations, and a combination of diagnostic techniques are essential.

Lateral flow immunogold assay as a rapid detection tool for screening of congenital hypothyroidism

ABSTRACT Congenital hypothyroidism (CH) is one of the most common preventable causes of mental retardation. The majority of infants are diagnosed after detection through newborn screening programs using thyroid-stimulating hormone (TSH) test. A rapid immunochromatographic lateral flow assay based on monoclonal antibodies (MAbs) colloidal gold nanoparticles was developed in a sandwich format for the detection of TSH. Two MAbs binding distinct TSH epitopes are used; one is conjugated to the detection reagent while the other is immobilized at the test line on the membrane. The colloidal gold was prepared by the reduction of gold salt coupled with MAbs and this optimal concentration was determined by spectrophotometry method. The sensitivity of our developed lateral flow immunoassay was determined using 5, 10, 15, 25 and 50 μUI/mL of TSH. The color intensity of the test line was directly proportional to the TSH concentration and the visual limit of detection was 10 μUI/mL. Twenty samples of umbilical cord serum were analyzed by the developed strips and the intensity of the signal was in agreement with the results obtained by the conventional radioimmunoassay method. The results suggest that this rapid test can be used in initial screening for congenital hypothyroidism especially in rural areas.

Monoclonal Antibodies Application in Lateral Flow Immunochromatographic Assays for Drugs of Abuse Detection.

Lateral flow assays (lateral flow immunoassays and nucleic acid lateral flow assays) have experienced a great boom in a wide variety of early diagnostic and screening applications. As opposed to conventional examinations (High Performance Liquid Chromatography, Polymerase Chain Reaction, Gas chromatography-Mass Spectrometry, etc.), they obtain the results of a sample’s analysis within a short period. In resource-limited areas, these tests must be simple, reliable, and inexpensive. In this review, we outline the production process of antibodies against drugs of abuse (such as heroin, amphetamine, benzodiazepines, cannabis, etc.), used in lateral flow immunoassays as revelation or detection molecules, with a focus on the components, the principles, the formats, and the mechanisms of reaction of these assays. Further, we report the monoclonal antibody advantages over the polyclonal ones used against drugs of abuse. The perspective on aptamer use for lateral flow assay development was also discussed as a possible alternative to antibodies in view of improving the limit of detection, sensitivity, and specificity of lateral flow assays.

Fast-track identification of CTX-M-extended-spectrum-\u03b2-lactamase- and carbapenemase-producing Enterobacterales in bloodstream infections: implications on the likelihood of deduction of antibiotic susceptibility in emergency and internal medicine departments

This study aims at presenting a reliable fast-track diagnostics for the detection of CTX-M ESBL- (CTX-M-p) and carbapenemase-producers (CA-p) directly from blood cultures (BCs) of patients with Enterobacterales (EB) bloodstream infections (BSIs) admitted in emergency and internal medicine departments and its contribution in estimation of in vitro antibiotic susceptibility. A fast-track workflow including MALDI-TOF species identification and two lateral flow immunochromatographic assays for the detection of CTX-M-p and CA-p directly from BCs was performed in parallel with conventional routine, and results were compared. A total of 236 BCs of patients suffering from EB BSI were included. Accuracy of the fast-track workflow ranged from 99.6 to 100%. Among E. coli isolates, CTX-M-p (20.5%) were susceptible to ceftolozane-tazobactam (C/T, 97%), ceftazidime-avibactam (CZA, 100%), and piperacillin-tazobactam (TZP, 84.8%), whereas CTX-M-and-main-carbapenemases-non-producer (CTX-M-CA-np, 79.5%) isolates were susceptible to all the antibiotics tested. Among K. pneumoniae isolates, CTX-M-p (23.3%) were poorly susceptible to TZP (40%) but widely susceptible to C/T (90%), CZA (100%), and amikacin (90%), whereas CTX-M-CA-np (55.8%) were also susceptible to cefepime. CA-p K. pneumoniae (20.9%) were susceptible to CZA (88.9%). All the species other than E. coli and K. pneumoniae were CTX-M-CA-np and were widely susceptible to the antibiotics tested except for isolates of the inducible and derepressed AmpC- or AmpC/ESBL-p species. Rapid identification of species and phenotype together with knowledge of local epidemiology may be crucial to determine the likelihood of deduction of in vitro antibiotic susceptibility on the same day of positive BC processing.

Development and validation of point-of-care testing of albuminuria for early screening of chronic kidney disease.

IntroductionChronic kidney disease (CKD) is a significant global health issue. As the prevalence of renal replacement therapy (RRT) in Thailand is increasing, early detection and management of CKD is the most important step to prevent CKD progression and the need for RRT. Current diagnostic tests for CKD are non‐specific and expensive. We aimed to develop and validate antibody‐based‐albumin point‐of‐care testing (POCT) to detect patients with impaired kidney function at early stage.MethodsThe prototype strip test was developed under the concept of competitive lateral flow immunochromatography assay, or strip test. Monoclonal antibodies (MAbs) to human serum albumin (HSA) were harvested from the hybridomas of spleen cells from immunized mice and mouse myeloma cells. Presence of MAbs was detected by enzyme‐linked immunosorbent assay (ELISA). Spot urine was obtained from patients with kidney disease, type I, or type II Diabetes Mellitus upon their visit at King Chulalongkorn Memorial Hospital during 2018–2019. All samples were analyzed for urine albumin with our POCT (CU microalbumin) and the other two commercial POCTs (Microalbu PHAN and MICRAL). The results were validated against standard method for urine microalbumin measurement. A urine microalbumin concentration of less than 20 ug/ml was defined as normal. The sensitivity, specificity, and predictive values were calculated in comparison with the standard laboratory method.ResultA total of 100 adult patients were included. CU microalbumin had a sensitivity of 86%, a specificity of 94%, and a positive predictive value of 96%. Our POCT showed good correlation with the laboratory results.ConclusionCU microalbumin correlated well with the standard method for quantitative measurement of urine albumin. Therefore, it has the potential for early screening of CKD, especially in primary health care facilities in resource limited settings.

Comparison of diagnostic accuracy for eight SARS-CoV-2 serological assays.

IntroductionSevere acute respiratory syndrome coronavirus 2 (SARS-CoV-2) serological tests have been suggested as an additional diagnostic tool in highly suspected cases with a negative molecular test and determination of seroprevalence in population. We compared the diagnostic performance of eight commercial serological assays for IgA, IgM, and IgG antibodies to the SARS-CoV-2 virus.Materials and methodsThe comparison study was performed on a total of 76 serum samples: 30 SARS-CoV-2 polymerase chain reaction (PCR)-negative and 46 SARS-CoV-2 PCR-positive patients with asymptomatic to severe disease and symptoms duration from 3-30 days. The study included: three rapid lateral flow immunochromatographic assays (LFIC), two enzyme-linked immunosorbent assays (ELISA), and three chemiluminescence immunoassays (CLIA).ResultsAgreement between IgM assays were minimal to moderate (kappa 0.26 to 0.63) and for IgG moderate to excellent (kappa 0.72 to 0.92). Sensitivities improved with > 10 days of symptoms and were: 30% to 89% for IgM; 89% to 100% for IgG; 96% for IgA; 100% for IgA/IgM combination; 96% for total antibodies. Overall specificities were: 90% to 100% for IgM; 85% to 100% for IgG; 90% for IgA; 70% for IgA/IgM combination; 100% for total antibodies. Diagnostic accuracy for IgG ELISA and CIA assays were excellent (AUC ≥ 0.90), without significant difference. IgA showed significantly better diagnostic accuracy than IgM (P < 0.001).ConclusionThere is high variability between IgM assays independently of the assay format, while IgG assays showed moderate to perfect agreement. The appropriate time for testing is crucial for the proper immunity investigation.

Development and validation of a lateral flow immunochromatographic assay for specific detection of viral hemorrhagic septicemia virus (VHSV, genotype IVa) in olive flounder (Paralichthys olivaceus)

A lateral flow immunochromatographic assay (LFIA) for the detection of viral hemorrhagic septicemia virus (VHSV, genotype IVa) was developed using seven anti-VHSV monoclonal antibodies (mAbs). The mAb 15E10 was not only used to bio-conjugate the VHSV antigen with colloidal gold nanoparticles but also as a capture antibody on the test line. The detection limit of the LFIA with VHSV isolates (genotype I-IV) was in the range of 105.05 to 105.55 TCID50/100 μL without any cross-reactivity with other fish viruses. Field-level validation of the assay using the heart of VHSV-infected and non-infected olive flounders (Paralichthys olivaceus) showed a specificity of 100% and sensitivity of 93.9% with a diagnostic effectiveness of 97.3%. The LFIA facilitates rapid detection of VHSV (genotype IVa) in olive flounders in farming facilities.

Rapid Serological Tests for SARS-CoV-2: Diagnostic Performance of 4 Commercial Assays

Objective: To assess the diagnostic performance of lateral flow immunochromatographic assays (LFAs) of 4 different manufacturers to identify SARS-CoV-2 antibodies (IgM, IgG, or total), comparing them with the nucleic acid amplification test (NAAT) or the clinical defined test (definite or probable SARS-CoV-2 infection, respectively). Methods: One hundred nineteen serum samples were randomly selected by convenience and distributed in the following groups: (1) group with SARS-CoV-2 infection (n = 82; RT-qPCR positive [definite, n = 70] and probable [n = 12]); (2) other diseases (n = 27; other viruses identified [n = 8] and SARS of other etiologies [n = 19]); and (3) healthy control group (n = 10). LFAs of 4 manufacturers were compared: MedTest Coronavirus (COVID-19) IgG/IgM (MedLevensohn, Brazil); COVID-19 IgG/IgM ECO Test (Ecodiagnóstica, Brazil); Camtech COVID-19 IgM/IgG Rapid Test Kit (Camtech Diagnostics Pte Ltd, Singapore); and 1-Step COVID-19 Test for total antibodies (Guangzhou Wondfo Biotech Co., China). Results: The 4 tests studied showed high diagnostic performance characteristics for the diagnoses of definite or probable SARS-CoV-2 infection. The best measures were for the Wondfo test: sensitivity (86.59%; 95% CI: 77.26–93.11%), specificity (100%; 90.51–100%), DOR (257; 60–1,008), LR+ (33.43; 4.82–231.85), LR− (0.13; 0.08–0.23), accuracy (90.76%; 84.06–95.29%), and Matthews correlation coefficient (MCC) 0.82. Although considering only the probable SARS-CoV-2 infection (PCR−) cases, all the kits studied showed limited values. Conclusion: Our data demonstrate the excellent performance of LFA for the diagnoses of definite or probable SARS-CoV-2 infection. There was substantial heterogeneity in sensitivities of IgM and IgG antibodies among the different kits. LFA tests cannot replace molecular diagnostics but should be used as an additional screening tool.

SARS-CoV-2 Seroprevalence and Accuracy Diagnostic Evaluation During a Covid-19 Outbreak in a Major Penitentiary Complex in Brazil, June-July 2020: A Population-Based Study

Summary: The pandemic of COVID-19 has presented as a threat to prison systems worldwide, as overcrowding, limited possibility of social distancing and sanitary restrictions favouring viral spread. SARS-CoV-2 seroprevalence studies in prison settings are important tools to understand transmission and to develop control measures. We aimed to estimate the overall SARS-CoV-2 seroprevalence and evaluated the accuracy of an antibody rapid test compared to a reference serological assay during a COVID-19 outbreak in a prison complex housing over 13,000 inmates in Brasília. Methods: We conducted a repeated serosurvey of IgM/IgG SARS-CoV-2 antibodies among inmates between June 17-July 1 (baseline) and July 8-22, 2020 (21-days follow-up). We obtained a randomized, stratified representative sample of each prison unit. Inmates who accepted to be part of the study were interviewed through a standardised questionnaire covering sociodemographic and clinical characteristics. Blood samples were collected from each participant for the evaluation of SARS-CoV-2 antibodies with a lateral-flow immunochromatographic assay (LFIA). Inmates with negative results in the first serosurvey were interviewed and tested for a second time to evaluate recent symptoms history and serological status 21 days later. Samples were also retested using a chemiluminescence enzyme immunoassay (CLIA) to compare SARS-CoV-2 seroprevalence and 21-days incidence, as well as to estimate the overall infection fatality rate (IFR) and determine the diagnostic accuracy of the LFIA test.Findings: We identified 485 eligible individuals and enrolled 460 participants (94.8%), distributed across four prison units. Baseline and 21-days follow-up seroprevalence were estimated at 52.0% (95%CI 44.9-59.0) and 56.7% (95%CI 48.2-65.3) with the LFIA test; and 80.7% (95%CI 74.1-87.3) and 81.1% (95%CI 74.4-87.8) with the CLIA test, with an overall IFR of 0.02%. There were 78.2% (95%CI 66.7-89.7) symptomatic inmates among the positive cases, and the main symptoms included changes in taste or smell, headache, and fever. Sensitivity and specificity of LFIA test were estimated at 43.4% and 83.3% for IgM; 46.5% and 91.5% for IgG; and 59.1% and 77.3% for combined tests. There was a fair agreement between LFIA and CLIA results (Kappa score 0.23).Interpretation: We found rapid viral spread and high seroprevalence of anti-SARS-CoV-2 antibodies within the prison complex. The occurrence of asymptomatic infection highlights the importance of periodic mass testing in addition to case-finding of symptomatic inmates, however the field performance of LFIA tests should be validated. We recommend that vaccination strategies consider the inclusion of persons deprived of liberty and prison staff in priority groups.Funding: EN, GASR, RH, WNA acknowledge the Brazilian Ministry of Education (MEC) for support the COVID-19 response by University of Brasília (#23106.028855/2020-74). RH, WMR and WNA acknowledge the Federal District Research Foundation (FAP-DF) for grants that supported this research (# 00193-00000495/2020-72). GASR, JHC, WMR, WNA acknowledge the National Research Council (CNPq) for grants that supported this research (# 402957/2020-2)Declaration of Interest: None to declare. Ethical Approval: The study was part of an epidemiological investigation conducted by the Brazilian Field Epidemiology Training Program/Ministry of Health as a response to a public health emergency, and it is supported by the national law 8.080/1990. Moreover, all participants provided informed consent and ethics approval was obtained under the CONEP protocol number 37007220.1.0000.0008.

Point-of-care diagnosis of COVID-19 disease based on antigen tests.

This review is focused on the laboratory diagnoses of the coronavirus disease 2019 (COVID-19) by recognizing the antigen of the causative agent SARS-CoV-2 virus. Various antigen tests are available in this moment and these tests are being further developed in order to reach a better diagnostic value. The issue is reviewed in a complex view. In this work, a complex survey of the current literature was made. The relevant and recent papers related to antigen tests of COVID-19 are discussed and cited. Basic specifications of the antigen tests and competitive methods were also scrutinized in the current literature. The survey of the current literature (years 2019 ‒ 2021) was made and diagnostic methods like lateral flow tests (lateral flow immunochromatographic assay) and various types of biosensors were specified as tools for COVID-19 diagnosis and their application to be used as a point-of-care test is considered. Small hand-held assays applicable in the point-of-care conditions for diagnosis of COVID-19 by analysis of SARS-CoV-2 antigen are the means of a growing interest and these means undergo a significant development leading to the improvements of their specifications and applicability to the current praxis. Merit of the assays is discussed in this paper (Tab. 3, Fig. 2, Ref. 109).

Lateral flow immunochromatographic assay on a single piece of paper.

Lateral flow immunochromatographic assays (LFIAs) are analytical devices used to detect the presence of one or more target analytes in a liquid sample. While LFIAs are one of the simplest and inexpensive types of immunoassays, they consist of multiple components (sample pad, conjugate pad, membrane, absorbent pad, backing card) and materials, requiring time-consuming device assembly. Here, we report a unique lateral flow immunochromatographic assay constructed from a single piece of cellulose paper, which is fabricated via laser cutting. Compared with conventional lateral flow immunochromatographic devices, this single-layer immunoassay enables simpler and faster fabrication, while minimizing material consumption and overall device costs. For proof-of-concept, this device was used to detect Plasmodium falciparum histidine-rich protein 2 (PfHRP2), a biomarker for malaria infection, which could be detected at concentrations as low as 4 ng mL-1 by the naked eye with no cross reactivity with other common Plasmodium protein biomarkers. While offering similar speed and ease-of-use as conventional LFIAs with a higher detection sensitivity than existing LFIAs for PfHRP2 detection, this single-layer lateral flow immunoassay has the potential to improve malaria testing, as well as the detection of other important protein biomarkers for point-of-care testing.

COVID-19 molecular level laboratory diagnoses.

Survey of actual literature and scientific reports was made. The most substantial analytical and diagnostical methods were identified and described. Principles and limitations of the methods are described, and actual papers are cited in this review. Analytical and diagnostical methods like Polymerase Chain Reaction (PCR), Loop-mediated isothermal Amplification (LAMP), Lateral Flow Immunochromatography Assay (LFIA), Enzyme-Linked Immunosorbent Assay (ELISA), biosensors and ChemiLuminescence ImmunoAssay (CLIA) are discussed for assay of viral particles, antigens and specific host antibodies in blood, serum, plasma, nasopharyngeal swab and other samples in order to diagnose COVID-19. The Coronavirus Disease 2019 (COVID-19) is an emerging disease that has spread over the world since the end of year 2019. The global epidemic pointed at the necessity to introduce sensitive methods for instrumental diagnosis of COVID-19 and distinguishing it from the other viral diseases. (Tab. 2, Ref. 96).