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Chimhashu TL, Verhoef H, Symington EA, Zandberg L, Baumgartner J, Malan L, Smuts CM, Feskens EJM, Melse-Boonstra A. Comparison of test performance of two commonly used multiplex assays to measure micronutrient and inflammatory markers in serum: results from a survey among pregnant women in South Africa. Br J Nutr 2024; 131:248-255. [PMID: 37560803 PMCID: PMC10751947 DOI: 10.1017/s0007114523001782] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2023] [Revised: 07/07/2023] [Accepted: 08/07/2023] [Indexed: 08/11/2023]
Abstract
The combined sandwich-ELISA (s-ELISA; VitMin Lab, Germany) and the Quansys Q-Plex™ Human Micronutrient Array (7-Plex) are multiplex serum assays that are used to assess population micronutrient status in low-income countries. We aimed to compare the agreement of five analytes, α-1-acid glycoprotein (AGP), C-reactive protein (CRP), ferritin, retinol-binding protein 4 (RBP4) and soluble transferrin receptor (sTfR) as measured by the 7-Plex and the s-ELISA. Serum samples were collected between March 2016 and December 2017. Pregnant women (n 249) were recruited at primary healthcare clinics in Johannesburg, and serum samples were collected between March 2016 and December 2017. Agreement between continuous measurements was assessed by Bland-Altman plots and concordance measures. Agreement in classifications of deficiency or inflammation was assessed by Cohen's kappa. Strong correlations (r > 0·80) were observed between the 7-Plex and s-ELISA for CRP and ferritin. Except for CRP, the 7-Plex assay gave consistently higher measurements than the s-ELISA. With the exception of CRP (Lin's ρ = 0·92), there was poor agreement between the two assays, with Lin's ρ < 0·90. Discrepancies of test results difference between methods increased as the serum concentrations rose. Cohen's kappa for all the five analytes was < 0·81 and ranged from slight agreement (vitamin A deficiency) to substantial (inflammation and Fe deficiency) agreement. The 7-Plex 1.0 is a research and or surveillance tool with potential for use in low-resource laboratories but cannot be used interchangeably with the s-ELISA. Further optimising and validation is required to establish its interchangeability with other validated methods.
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Affiliation(s)
- Tsitsi Letwin Chimhashu
- Division of Human Nutrition and Health, Wageningen University & Research, Wageningen, The Netherlands
- Centre of Excellence for Nutrition, North-West University, Potchefstroom, South Africa
| | - Hans Verhoef
- Division of Human Nutrition and Health, Wageningen University & Research, Wageningen, The Netherlands
| | - Elizabeth A. Symington
- Department of Life and Consumer Sciences, University of South Africa, Johannesburg, South Africa
| | - Lizelle Zandberg
- Centre of Excellence for Nutrition, North-West University, Potchefstroom, South Africa
| | - Jeannine Baumgartner
- Centre of Excellence for Nutrition, North-West University, Potchefstroom, South Africa
- Department of Nutritional Sciences, King’s College, London, UK
| | - Linda Malan
- Centre of Excellence for Nutrition, North-West University, Potchefstroom, South Africa
| | | | - Edith J. M. Feskens
- Division of Human Nutrition and Health, Wageningen University & Research, Wageningen, The Netherlands
| | - Alida Melse-Boonstra
- Division of Human Nutrition and Health, Wageningen University & Research, Wageningen, The Netherlands
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Rathod V, Kadam L, Gautam M, Gumma PD, Marke K, Asokanathan C, Douglas-Bardsley A, Hassell L, Bhandare S, Gupta S, Parekh S, Pujari P, Rao H, Sharma H, Shaligram U, Gairola S. Multiplexed bead-based assay for the simultaneous quantification of human serum IgG antibodies to tetanus, diphtheria, pertussis toxin, filamentous hemagglutinin, and pertactin. Front Immunol 2023; 14:1190404. [PMID: 37342321 PMCID: PMC10278353 DOI: 10.3389/fimmu.2023.1190404] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2023] [Accepted: 05/02/2023] [Indexed: 06/22/2023] Open
Abstract
Background Luminex bead-based assays offer multiplexing to test antibodies against multiple antigens simultaneously; however, this requires validation using internationally certified reference standards. Therefore, there is an urgent need to characterize existing reference standards for the standardization of multiplex immunoassays (MIAs). Here, we report the development and validation of an MIA for the simultaneous estimation of levels of human serum immunoglobulin G (IgG) antibodies for pertussis toxin (PT), filamentous hemagglutinin (FHA), pertactin (PRN), diphtheria toxoid (DT), and tetanus toxoid (TT). Methods The MIA was assessed using a panel of human serum samples and WHO reference standards. The WHO reference standards were also studied for suitability in the MIA. Purified antigens (PT, FHA, PRN, DT, and TT) were coupled to the spectrally unique magnetic carboxylated microspheres. The method was validated in accordance with the United States Food and Drug Administration (US FDA), European Medicines Agency (EMA), and the International Committee of Harmonization Multidisciplinary (ICH M10) guidelines, and parameters such as precision, accuracy, dilutional linearity, assay range, robustness, and stability were assessed. Method agreements with commercially available IgG enzyme-linked immunosorbent assay (ELISA) assays were also evaluated. In addition, the study assessed the level of correlation between the IgG levels estimated by the MIA and the cell-based neutralizing antibody assays for PT and DT. Results We identified that an equimix of WHO international standards (i.e., 06/142, 10/262, and TE-3) afforded the best dynamic range for all the antigens in the MIA. For all five antigens, we observed that the back-fitted recoveries using the four-parameter logistic (4-PL) regression fits ranged between 80% and 120% for all calibration levels, and the percentage coefficient of variation (% CV) was < 20%. In addition, the difference in mean fluorescence intensity (MFI) between the monoplex and multiplex format was < 10% for each antigen, indicating no crosstalk among the beads. The MIA also showed good agreement with conventional and commercially available assays, and a positive correlation (> 0.75) with toxin neutralization assays for PT and DT was observed. Conclusion The MIA that was calibrated in accordance with WHO reference standards demonstrated increased sensitivity, reproducibility, and high throughput capabilities, allowing for the design of robust studies that evaluate both natural and vaccine-induced immunity.
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Affiliation(s)
- Vishal Rathod
- Clinical Bioanalytical Laboratory, Serum Institute of India Pvt. Ltd., Pune, Maharashtra, India
| | - Laxmikant Kadam
- Clinical Bioanalytical Laboratory, Serum Institute of India Pvt. Ltd., Pune, Maharashtra, India
| | - Manish Gautam
- Clinical Bioanalytical Laboratory, Serum Institute of India Pvt. Ltd., Pune, Maharashtra, India
| | - Prabhu Dasu Gumma
- Clinical Bioanalytical Laboratory, Serum Institute of India Pvt. Ltd., Pune, Maharashtra, India
| | - Kevin Marke
- Science, Research and Innovation, Medicines, and Healthcare Products Regulatory Agency, South Mimms, United Kingdom
| | - Cathy Asokanathan
- Science, Research and Innovation, Medicines, and Healthcare Products Regulatory Agency, South Mimms, United Kingdom
| | - Alex Douglas-Bardsley
- Science, Research and Innovation, Medicines, and Healthcare Products Regulatory Agency, South Mimms, United Kingdom
| | - Laura Hassell
- Science, Research and Innovation, Medicines, and Healthcare Products Regulatory Agency, South Mimms, United Kingdom
| | - Sachin Bhandare
- Clinical Bioanalytical Laboratory, Serum Institute of India Pvt. Ltd., Pune, Maharashtra, India
| | - Sumit Gupta
- Clinical Bioanalytical Laboratory, Serum Institute of India Pvt. Ltd., Pune, Maharashtra, India
| | - Sameer Parekh
- Clinical Bioanalytical Laboratory, Serum Institute of India Pvt. Ltd., Pune, Maharashtra, India
| | - Pramod Pujari
- Clinical Bioanalytical Laboratory, Serum Institute of India Pvt. Ltd., Pune, Maharashtra, India
| | - Harish Rao
- Clinical Bioanalytical Laboratory, Serum Institute of India Pvt. Ltd., Pune, Maharashtra, India
| | - Hitt Sharma
- Clinical Bioanalytical Laboratory, Serum Institute of India Pvt. Ltd., Pune, Maharashtra, India
| | - Umesh Shaligram
- Clinical Bioanalytical Laboratory, Serum Institute of India Pvt. Ltd., Pune, Maharashtra, India
| | - Sunil Gairola
- Clinical Bioanalytical Laboratory, Serum Institute of India Pvt. Ltd., Pune, Maharashtra, India
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DeBoer MD, Elwood SE, Platts-Mills JA, McDermid JM, Scharf RJ, Rogawski McQuade ET, Jatosh S, Houpt ER, Mduma E. Association of Circulating Biomarkers with Growth and Cognitive Development in Rural Tanzania: A Secondary Analysis of the Early Life Interventions in Childhood Growth and Development In Tanzania (ELICIT) Study. J Nutr 2023; 153:1453-1460. [PMID: 36963502 DOI: 10.1016/j.tjnut.2023.03.020] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2023] [Revised: 02/09/2023] [Accepted: 03/15/2023] [Indexed: 03/26/2023] Open
Abstract
BACKGROUND Children in low-resource areas experience nutritional and infection challenges delaying growth and cognitive development. OBJECTIVE Our goal was to assess for associations of circulating biomarkers related to nutrition and inflammation, with growth and developmental outcomes among children in a birth cohort in a resource-poor area in rural Tanzania. METHODS We assessed data from 1120 children participating in the Early Life Interventions for Childhood Growth and Development in Tanzania (ELICIT) study. At age 12 and 18 months participants had blood tests performed for hemoglobin, collagen-X, insulin-like growth factor-1 (IGF-1), fibroblast growth-factor-21 (FGF21), thyroglobulin, ferritin, soluble transferrin receptor (sTFR), retinol binding protein-4 (RBP4), C-reactive protein (CRP), alpha(1)-acid glycoprotein (AGP), and CD14. At 18 months, participants had anthropometry measured and converted to z-scores for length-for-age (LAZ), weight-for-age (WAZ) and head-circumference-for-age (HCZ) and had the Malawi Developmental Assessment Tool (MDAT) performed to evaluate cognitive development. We performed linear regression assessing biomarkers (predictor variable) on anthropometry and MDAT scores (dependent variables), adjusted for sex, socioeconomic status and baseline values. RESULTS There was a high degree of intra-factor correlation between 12 and 18 months, and inter-factor correlation between biomarkers. IGF-1 and sTFR were positively- and FGF21 and ferritin negatively-associated with LAZ 18 months, while collagen-X and CD14 were additionally associated with recent linear growth. Only markers predominantly related to nutrition were consistently linked with WAZ at 18 months, while RBP4 and AGP were additionally associated with recent change in WAZ. IGF-1 was positively- and thyroglobulin, RBP4 and CD14 negatively linked to MDAT scores. IGF-1 was the only factor linked to both 18-month LAZ and MDAT. CONCLUSIONS Individual biomarkers were consistently linked to growth and cognitive outcomes, providing support for relationships between nutrition and inflammation in early child development. Further research is needed to assess overlaps in how biomarker-related processes interact with both growth and learning.
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Affiliation(s)
- Mark D DeBoer
- Department of Pediatrics, University of Virginia, Charlottesville, VA, USA.
| | - Sarah E Elwood
- Division of Infectious Diseases & International Health, University of Virginia, Charlottesville, VA, USA
| | - James A Platts-Mills
- Division of Infectious Diseases & International Health, University of Virginia, Charlottesville, VA, USA
| | - Joann M McDermid
- Division of Infectious Diseases & International Health, University of Virginia, Charlottesville, VA, USA
| | - Rebecca J Scharf
- Department of Pediatrics, University of Virginia, Charlottesville, VA, USA; Division of Infectious Diseases & International Health, University of Virginia, Charlottesville, VA, USA
| | | | - Samwel Jatosh
- Haydom Global Health Research Centre, Haydom Lutheran Hospital, Haydom, Tanzania
| | - Eric R Houpt
- Division of Infectious Diseases & International Health, University of Virginia, Charlottesville, VA, USA
| | - Estomih Mduma
- Haydom Global Health Research Centre, Haydom Lutheran Hospital, Haydom, Tanzania
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4
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Brindle E, Lillis L, Barney R, Bansil P, Arredondo F, Craft NE, Murphy E, Boyle DS. Multiplexed micronutrient, inflammation, and malarial antigenemia assessment using a plasma fractionation device. PLoS One 2022; 17:e0277835. [PMID: 36409692 PMCID: PMC9678258 DOI: 10.1371/journal.pone.0277835] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2021] [Accepted: 11/03/2022] [Indexed: 11/22/2022] Open
Abstract
Processing and storing blood samples for future analysis of biomarkers can be challenging in resource limited environments. The preparation of dried blood spots (DBS) from finger-stick collection of whole blood is a widely used and established method as DBS are biosafe, and allow simpler field processing, storage, and transport protocols than serum or plasma. Therefore, DBS are commonly used in population surveys to assess infectious disease and/or micronutrient status. Recently, we reported that DBS can be used with the Q-plex™ Human Micronutrient 7-plex Array (MN 7-plex), a multiplexed immunoassay. This tool can simultaneously quantify seven protein biomarkers related to micronutrient deficiencies (iodine, iron and vitamin A), inflammation, and malarial antigenemia using plasma or serum. Serum ferritin, an iron biomarker, cannot be measured from DBS due to red blood cell (RBC) ferritin content confounding the results. In this study, we assess a simple blood fractionation tool that passively separates plasma from other blood components via diffusion through a membrane into a plasma collection disc (PCD). We evaluated the concordance of MN 7-plex analyte concentrations from matched panels of eighty-eight samples of PCD, DBS, and wet plasma prepared from anticoagulated venous whole blood. The results showed good correlations of >0.93 between the eluates from PCD and DBS for each analyte except ferritin; while correlations seen for plasma/PCD were weaker. However, the recovery rate of the analytes from the PCD were better than those from DBS. The serum ferritin measures from the PCD were highly correlated to wet plasma samples (0.85). This suggests that surveillance for iron status in low resource settings can be improved over the current methods restricted to only measuring sTfR in DBS. When used in combination with the MN 7-plex, all seven biomarkers can be simultaneously measured using eluates from the PCDs.
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Affiliation(s)
- Eleanor Brindle
- Center for Studies in Demography and Ecology, University of Washington, Seattle, Washington, United States of America
- PATH, Seattle, Washington, United States of America
| | | | | | - Pooja Bansil
- PATH, Seattle, Washington, United States of America
| | - Francisco Arredondo
- Dept of Medicine, Duke University, Durham, North Carolina, United States of America
| | - Neal E. Craft
- Craft Nutrition Consulting, Elm City, North Carolina, United States of America
| | | | - David S. Boyle
- PATH, Seattle, Washington, United States of America
- * E-mail:
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5
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Brindle E, Lillis L, Barney R, Bansil P, Hess SY, Wessells KR, Ouédraogo CT, Arredondo F, Barker MK, Craft NE, Fischer C, Graham JL, Havel PJ, Karakochuk CD, Zhang M, Mussai EX, Mapango C, Randolph JM, Wander K, Pfeiffer CM, Murphy E, Boyle DS. A multicenter analytical performance evaluation of a multiplexed immunoarray for the simultaneous measurement of biomarkers of micronutrient deficiency, inflammation and malarial antigenemia. PLoS One 2021; 16:e0259509. [PMID: 34735520 PMCID: PMC8568126 DOI: 10.1371/journal.pone.0259509] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2021] [Accepted: 10/20/2021] [Indexed: 11/19/2022] Open
Abstract
A lack of comparative data across laboratories is often a barrier to the uptake and adoption of new technologies. Furthermore, data generated by different immunoassay methods may be incomparable due to a lack of harmonization. In this multicenter study, we describe validation experiments conducted in a single lab and cross-lab comparisons of assay results to assess the performance characteristics of the Q-plex™ 7-plex Human Micronutrient Array (7-plex), an immunoassay that simultaneously quantifies seven biomarkers associated with micronutrient (MN) deficiencies, inflammation and malarial antigenemia using plasma or serum; alpha-1-acid glycoprotein, C-reactive protein, ferritin, histidine-rich protein 2, retinol binding protein 4, soluble transferrin receptor, and thyroglobulin. Validations included repeated testing (n = 20 separately prepared experiments on 10 assay plates) in a single lab to assess precision and linearity. Seven independent laboratories tested 76 identical heparin plasma samples collected from a cohort of pregnant women in Niger using the same 7-plex assay to assess differences in results across laboratories. In the analytical validation experiments, intra- and inter-assay coefficients of variation were acceptable at <6% and <15% respectively and assay linearity was 96% to 99% with the exception of ferritin, which had marginal performance in some tests. Cross-laboratory comparisons showed generally good agreement between laboratories in all analyte results for the panel of 76 plasma specimens, with Lin's concordance correlation coefficient values averaging ≥0.8 for all analytes. Excluding plates that would fail routine quality control (QC) standards, the inter-assay variation was acceptable for all analytes except sTfR, which had an average inter-assay coefficient of variation of ≥20%. This initial cross-laboratory study demonstrates that the 7-plex test protocol can be implemented by users with some experience in immunoassay methods, but familiarity with the multiplexed protocol was not essential.
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Affiliation(s)
- Eleanor Brindle
- Center for Studies in Demography and Ecology, University of Washington, Seattle, Washington, United States of America
| | | | | | - Pooja Bansil
- PATH, Seattle, Washington, United States of America
| | - Sonja Y. Hess
- Department of Molecular Biosciences, School of Veterinary Medicine and Department of Nutrition, University of California, Davis, California, United States of America
| | - K. Ryan Wessells
- Department of Molecular Biosciences, School of Veterinary Medicine and Department of Nutrition, University of California, Davis, California, United States of America
| | - Césaire T. Ouédraogo
- Department of Molecular Biosciences, School of Veterinary Medicine and Department of Nutrition, University of California, Davis, California, United States of America
- Helen Keller International, Niamey, Niger
| | - Francisco Arredondo
- Duke University Medical Ctr. Durham, Durham, North Carolina, United States of America
| | - Mikaela K. Barker
- Faculty of Land and Food Systems, University of British Columbia, Vancouver, British Columbia, Canada
| | - Neal E. Craft
- Craft Nutrition Consulting, Elm City, North Carolina, United States of America
| | - Christina Fischer
- Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America
| | - James L. Graham
- Department of Molecular Biosciences, School of Veterinary Medicine and Department of Nutrition, University of California, Davis, California, United States of America
| | - Peter J. Havel
- Department of Molecular Biosciences, School of Veterinary Medicine and Department of Nutrition, University of California, Davis, California, United States of America
| | - Crystal D. Karakochuk
- Faculty of Land and Food Systems, University of British Columbia, Vancouver, British Columbia, Canada
| | - Mindy Zhang
- Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America
| | - Ei-Xia Mussai
- Faculty of Land and Food Systems, University of British Columbia, Vancouver, British Columbia, Canada
| | - Carine Mapango
- Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America
| | - Jody M. Randolph
- Department of Molecular Biosciences, School of Veterinary Medicine and Department of Nutrition, University of California, Davis, California, United States of America
| | - Katherine Wander
- Binghamton University (SUNY), Binghamton, New York, United States of America
| | - Christine M. Pfeiffer
- Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America
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Arndt MB, Cantera JL, Mercer LD, Kalnoky M, White HN, Bizilj G, Boyle DS, de Hostos EL, Choy RKM. Validation of the Micronutrient and Environmental Enteric Dysfunction Assessment Tool and evaluation of biomarker risk factors for growth faltering and vaccine failure in young Malian children. PLoS Negl Trop Dis 2020; 14:e0008711. [PMID: 32997666 PMCID: PMC7549819 DOI: 10.1371/journal.pntd.0008711] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2019] [Revised: 10/12/2020] [Accepted: 08/13/2020] [Indexed: 12/31/2022] Open
Abstract
Environmental enteric dysfunction (EED) is an intestinal disorder common among children in low-resource settings and is associated with increased risk of growth stunting, cognitive deficits, and reduced oral vaccine immunogenicity. The Micronutrient and EED Assessment Tool (MEEDAT) is a multiplexed immunoassay that measures biomarkers previously associated with child growth faltering and/or oral vaccine immunogenicity: intestinal fatty acid–binding protein (I-FABP), soluble CD14 (sCD14), insulin-like growth factor 1 (IGF-1), and fibroblast growth factor 21 (FGF21). MEEDAT also measures systemic inflammation (α1-acid glycoprotein, C-reactive protein), ferritin, soluble transferrin receptor, retinol binding protein 4, thyroglobulin, and Plasmodium falciparum antigenemia (histidine-rich protein 2). The performance of MEEDAT was compared with commercially available enzyme-linked immunosorbent assays (ELISAs) using 300 specimens from Malian infant clinical trial participants. Regression methods were used to test if MEEDAT biomarkers were associated with seroconversion to meningococcal A conjugate vaccine (MenAV), yellow fever vaccine (YFV), and pentavalent rotavirus vaccine (PRV) after 28 days, or with growth faltering over 12 weeks. The Pearson correlations between the MEEDAT and ELISA results were 0.97, 0.86, 0.80, and 0.97 for serum I-FABP, sCD14, IGF-1, and FGF21, respectively. There were significant associations between I-FABP concentration and the probability of PRV IgG seroconversion and between IGF-1 concentration and the probability of YFV seroconversion. In multivariable models neither association remained significant, however there was a significant negative association between AGP concentration and YFV seroconversion. GLP-2 and sCD14 concentrations were significantly negatively associated with 12-week change in weight-for-age z-score and weight-for-height z-score in multivariable models. MEEDAT performed well in comparison to commercially-available ELISAs for the measurement of four analytes for EED and growth hormone resistance. Adoption of MEEDAT in low-resource settings could help accelerate the identification of interventions that prevent or treat child stunting and interventions that boost the immunogenicity of child vaccinations. Environmental enteric dysfunction (EED) is an intestinal disorder common among children in low-resource settings and has been associated with increased risk of growth stunting, cognitive deficits, and reduced oral vaccine immunogenicity. A key challenge to identifying children with EED at highest risk of morbid sequelae is the lack of validated predictive biomarkers. Ongoing clinical studies are testing and validating EED biomarkers in child populations at risk for stunting, yet testing multiple biomarkers commonly requires specialized equipment, complex methods, resources, and considerable effort. The Micronutrient and EED Assessment Tool (MEEDAT) is a multiplexed immunoassay that measures biomarkers associated with child growth faltering and oral vaccine immunogenicity, and biomarkers indicative of systemic inflammation and micronutrient deficiencies. The performance of MEEDAT was well-correlated with commercial monoplex assays in specimens from children living in a low-resource setting in the present study. MEEDAT biomarkers were associated with growth outcomes and seroconversion in response to several vaccines. MEEDAT has the potential to reduce the time and cost of evaluating impact of interventions targeting EED.
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Affiliation(s)
- Michael B. Arndt
- PATH, Seattle, Washington, United States of America
- Department of Global Health, University of Washington, United States of America
- * E-mail:
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Restrepo-Gallego M, Díaz LE, Rondó PHC. Classic and emergent indicators for the assessment of human iron status. Crit Rev Food Sci Nutr 2020; 61:2827-2840. [PMID: 32619106 DOI: 10.1080/10408398.2020.1787326] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Iron deficiency is the leading cause of anemia, a significant global public health problem. Different methods exist for assessing iron nutritional status, including laboratory tests that focus on storage, transportation, and iron functional compartment parameters. Classical markers such as bone marrow, serum iron, ferritin, hemoglobin, erythrocyte parameters, transferrin, transferrin receptors, and zinc protoporphyrin are discussed in this review. Additional parameters calculated from these indicators, including transferrin saturation, ferritin index and Thomas plot, and some emergent parameters such as hepcidin, erythroferrone, and low hemoglobin density are also discussed. There is no a single indicator for assessing iron nutritional status. Therefore, the use of more than one indicator may be the best practice to obtain the correct diagnosis, also considering the influence of inflammation/infection on many of these indicators. The constant validation of the current parameters, the improvement of assessment methods, and the identification of new indicators will be the key to refine the assessment of iron nutritional status and the right choice of treatment for its improvement.
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Affiliation(s)
| | - Luis E Díaz
- Doctorate Program in Bioscience, La Sabana University, Chía, Colombia
| | - Patrícia H C Rondó
- Department of Nutrition, School of Public Health, University of São Paulo, São Paulo, Brazil
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8
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The Quansys multiplex immunoassay for serum ferritin, C-reactive protein, and α-1-acid glycoprotein showed good comparability with reference-type assays but not for soluble transferrin receptor and retinol-binding protein. PLoS One 2019; 14:e0215782. [PMID: 31034479 PMCID: PMC6488062 DOI: 10.1371/journal.pone.0215782] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2019] [Accepted: 04/08/2019] [Indexed: 01/08/2023] Open
Abstract
The Quansys multiplex (Q-Plex) measures ferritin (Fer), soluble transferrin receptor (sTfR), C-reactive protein (CRP), α-1-acid glycoprotein (AGP), and retinol-binding protein (RBP). We compared Q-Plex results with reference-type assays and evaluated Q-Plex performance. Pearson correlation and Lin’s concordance coefficients between the Q-Plex and reference assay were: Fer 0.98 and 0.91, sTfR 0.88 and 0.35, CRP 0.98 and 0.98, AGP 0.82 and 0.81, and RBP 0.68 and 0.31, respectively. The median relative difference between the Q-Plex and reference assay were: Fer -2.4%, sTfR 107%, CRP 0.03%, AGP -1.3%, and RBP 51%. The Q-Plex intra-assay CVs were <5%; the inter-assay CVs were higher: Fer 11%, sTfR 14%, CRP 9.3%, AGP 7.5%, and RBP 19%. EDTA plasma produced 74% higher Q-Plex sTfR concentrations compared to serum. Analyte stability was good for ≤5 freeze-thaw cycles. After adjusting Q-Plex data to the reference assays, sensitivity and specificity were >85% for Fer and CRP; specificity was >85% for sTfR, AGP, and RBP. Using performance criteria derived from biologic variation, Fer, CRP, and AGP met the minimum allowable imprecision (<10.7%, <31.7%, and <8.5%, respectively) and difference from the reference assay (<±7.7%, <±32.7%, and <±10.3%, respectively), while sTfR and RBP exceeded these thresholds (<8.5% and <7.8% for imprecision and <±7.7% and <±12% for difference, respectively). The Q-Plex measures multiple biomarkers simultaneously, is easy to perform, and uses small sample volumes. With some improvements in accuracy and precision (i.e., sTfR and RBP), this assay could be a useful tool for low-resource laboratories conducting micronutrient surveys for epidemiologic screening applications. These findings need to be verified using other populations, particularly those with inadequate micronutrient status.
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Karakochuk CD, Hess SY, Moorthy D, Namaste S, Parker ME, Rappaport AI, Wegmüller R, Dary O. Measurement and interpretation of hemoglobin concentration in clinical and field settings: a narrative review. Ann N Y Acad Sci 2019; 1450:126-146. [PMID: 30652320 DOI: 10.1111/nyas.14003] [Citation(s) in RCA: 42] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2018] [Revised: 12/16/2018] [Accepted: 12/26/2018] [Indexed: 12/26/2022]
Abstract
Anemia affects over 800 million women and children globally. Defined as a limited or insufficient functional red blood cell supply in peripheral blood, anemia causes a reduced oxygen supply to tissues and can have serious health consequences for women and children. Hemoglobin (Hb) concentration is most commonly measured for anemia diagnosis. Methods to measure Hb are usually invasive (requiring a blood sample); however, advances in diagnostic and clinical chemistry over the past decade have led to the development of new noninvasive methods. Accurate diagnosis at the individual level is important to identify individuals who require treatment. At the population level, anemia prevalence estimates are often the impetus for national nutrition policies or programs. Thus, it is essential that methods for Hb measurement are sensitive, specific, accurate, and reproducible. The objective of our narrative review is to describe the basic principles, advantages, limitations, and quality control issues related to methods of Hb measurement in clinical and field settings. We also discuss other biomarkers and tests that can help to determine the severity and underlying causes of anemia. In conclusion, there are many established and emerging methods to measure Hb concentration, each with their own advantages, limitations, and factors to consider before use.
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Affiliation(s)
- Crystal D Karakochuk
- Food, Nutrition and Health, University of British Columbia, Vancouver, British Columbia, Canada
| | - Sonja Y Hess
- Department of Nutrition, University of California Davis, Davis, California
| | - Denish Moorthy
- USAID-funded Strengthening Partnerships, Results, and Innovation in Nutrition Globally Project, John Snow Inc., Arlington, Virginia
| | | | - Megan E Parker
- Nutrition Innovation, Maternal Newborn and Child Health and Nutrition, PATH, Seattle, Washington
| | - Aviva I Rappaport
- Centre for Global Child Health, Hospital for Sick Children, Toronto, Ontario, Canada
| | - Rita Wegmüller
- GroundWork, Fläsch, Switzerland.,Medical Research Council Unit the Gambia, Keneba, the Gambia
| | - Omar Dary
- Nutrition Division, Office of Maternal and Child Health and Nutrition, Bureau for Global Health, United States Agency for International Development, Washington, DC
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- Food, Nutrition and Health, University of British Columbia, Vancouver, British Columbia, Canada
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10
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Brindle E, Lillis L, Barney R, Bansil P, Lyman C, Boyle DS. Measurement of micronutrient deficiency associated biomarkers in dried blood spots using a multiplexed immunoarray. PLoS One 2019; 14:e0210212. [PMID: 30620768 PMCID: PMC6324783 DOI: 10.1371/journal.pone.0210212] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2018] [Accepted: 12/17/2018] [Indexed: 11/18/2022] Open
Abstract
Simplifying blood collection is often critical when collecting specimens in remote and/or austere settings. The use of dried blood spots (DBS) offers a practical collection method suitable for a wide variety of analytes. A small volume of whole blood can be obtained rapidly through a minimally invasive heel- or finger-stick using a disposable safety lancet. Once dried, the samples require no further processing, are stable for months or longer, pose minimal risk of disease transmission, and are easy to ship. DBS are often used in demographic health surveys to assess infectious disease status in vulnerable populations. These samples can be used to screen biomarkers of micronutrient deficiency (MND) and inflammation. We recently described a multiplexed immunoarray, the Q-plex human micronutrient array, which can simultaneously quantify seven biomarkers related to MND, inflammation and malarial antigenemia using plasma (alpha-1-acid glycoprotein, C-reactive protein, ferritin, histidine-rich protein 2, retinol binding protein, soluble transferrin receptor, and thyroglobulin). In this work, we present a protocol for preparing eluates from DBS samples and their measurement using a modified protocol for this new tool. We evaluated the concordance of analyte concentrations (excluding ferritin) from a panel ninety samples of DBS prepared from anticoagulated venous blood and paired K2-EDTA plasma. The results show high correlation between DBS eluates and wet plasma for five of the six analytes screened, suggesting the Q-plex human micronutrient array can be used with DBS samples, but also highlighting that anticoagulants can have a negative effects on some test components.
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Affiliation(s)
- Eleanor Brindle
- Center for Studies in Demography and Ecology, University of Washington, Seattle, Washington, United States of America
| | | | | | - Pooja Bansil
- PATH, Seattle, Washington, United States of America
| | | | - David S. Boyle
- PATH, Seattle, Washington, United States of America
- * E-mail:
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11
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Lynch S, Pfeiffer CM, Georgieff MK, Brittenham G, Fairweather-Tait S, Hurrell RF, McArdle HJ, Raiten DJ. Biomarkers of Nutrition for Development (BOND)-Iron Review. J Nutr 2018; 148:1001S-1067S. [PMID: 29878148 PMCID: PMC6297556 DOI: 10.1093/jn/nxx036] [Citation(s) in RCA: 172] [Impact Index Per Article: 28.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2017] [Revised: 05/27/2017] [Accepted: 11/07/2017] [Indexed: 12/20/2022] Open
Abstract
This is the fifth in the series of reviews developed as part of the Biomarkers of Nutrition for Development (BOND) program. The BOND Iron Expert Panel (I-EP) reviewed the extant knowledge regarding iron biology, public health implications, and the relative usefulness of currently available biomarkers of iron status from deficiency to overload. Approaches to assessing intake, including bioavailability, are also covered. The report also covers technical and laboratory considerations for the use of available biomarkers of iron status, and concludes with a description of research priorities along with a brief discussion of new biomarkers with potential for use across the spectrum of activities related to the study of iron in human health.The I-EP concluded that current iron biomarkers are reliable for accurately assessing many aspects of iron nutrition. However, a clear distinction is made between the relative strengths of biomarkers to assess hematological consequences of iron deficiency versus other putative functional outcomes, particularly the relationship between maternal and fetal iron status during pregnancy, birth outcomes, and infant cognitive, motor and emotional development. The I-EP also highlighted the importance of considering the confounding effects of inflammation and infection on the interpretation of iron biomarker results, as well as the impact of life stage. Finally, alternative approaches to the evaluation of the risk for nutritional iron overload at the population level are presented, because the currently designated upper limits for the biomarker generally employed (serum ferritin) may not differentiate between true iron overload and the effects of subclinical inflammation.
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Affiliation(s)
| | - Christine M Pfeiffer
- National Center for Environmental Health, Centers for Disease Control and Prevention, Atlanta, GA
| | - Michael K Georgieff
- Division of Neonatology, Department of Pediatrics, University of Minnesota School of Medicine, Minneapolis, MN
| | - Gary Brittenham
- Division of Pediatric Hematology, Oncology and Stem Cell Transplant, Department of Pediatrics, Columbia University College of Physicians and Surgeons, New York, NY
| | - Susan Fairweather-Tait
- Department of Nutrition, Norwich Medical School, Norwich Research Park, University of East Anglia, Norwich NR4 7JT, UK
| | - Richard F Hurrell
- Institute of Food, Nutrition and Health, Swiss Federal Institute of Technology, Zurich, Switzerland
| | - Harry J McArdle
- Rowett Institute of Nutrition and Health, University of Aberdeen, Aberdeen AB21 9SB, UK
| | - Daniel J Raiten
- Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD), National Institutes of Health (NIH)
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12
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Garcia-Casal MN, Peña-Rosas JP, Urrechaga E, Escanero JF, Huo J, Martinez RX, Lopez-Perez L. Performance and comparability of laboratory methods for measuring ferritin concentrations in human serum or plasma: A systematic review and meta-analysis. PLoS One 2018; 13:e0196576. [PMID: 29723227 PMCID: PMC5933730 DOI: 10.1371/journal.pone.0196576] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2017] [Accepted: 04/16/2018] [Indexed: 01/21/2023] Open
Abstract
BACKGROUND Different laboratory methods are used to quantify ferritin concentrations as a marker of iron status. A systematic review was undertaken to assess the accuracy and comparability of the most used methods for ferritin detection. METHODS AND FINDINGS National and regional databases were searched for prospective, retrospective, sectional, longitudinal and case-control studies containing the characteristics and performance of at least one method for serum/plasma ferritin determinations in humans published to date. The analysis included the comparison between at least 2 methods detailing: sensitivity, precision, accuracy, predictive values, inter-methods adjustment, and use of international reference materials. Pooled method performance was analyzed for each method and across methods. OUTCOMES Search strategy identified 11893 records. After de-duplication and screening 252 studies were assessed, including 187 studies in the qualitative analysis and 148 in the meta-analysis. The most used methods included radiometric, nonradiometric and agglutination assays. The overall within-run imprecision for the most reported ferritin methods was 6.2±3.4% (CI 5.69-6.70%; n = 171), between-run imprecision 8.9±8.7% (CI 7.44-10.35%; n = 136), and recovery rate 95.6% (CI 91.5-99.7%; n = 94). The pooled regression coefficient was 0.985 among all methods analyzed, and 0.984 when comparing nonradiometric and radiometric methods, without statistical differences in ferritin concentration ranging from 2.3 to 1454 μμg/L. CONCLUSION The laboratory methods most used to determine ferritin concentrations have comparable accuracy and performance. Registered in PROSPERO CRD42016036222.
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Affiliation(s)
- Maria N. Garcia-Casal
- Evidence and Programme Guidance, Department of Nutrition for Health and Development, World Health Organization, Geneva, Switzerland
| | - Juan P. Peña-Rosas
- Evidence and Programme Guidance, Department of Nutrition for Health and Development, World Health Organization, Geneva, Switzerland
| | | | - Jesus F. Escanero
- Department of Pharmacology and Physiology, Faculty of Medicine, University of Zaragoza, Zaragoza, Spain
| | - Junsheng Huo
- Department of Food Science and Technology, Institute of Nutrition and Food Safety, Beijing, China
| | - Ricardo X. Martinez
- Evidence and Programme Guidance, Department of Nutrition for Health and Development, World Health Organization, Geneva, Switzerland
| | - Lucero Lopez-Perez
- Evidence and Programme Guidance, Department of Nutrition for Health and Development, World Health Organization, Geneva, Switzerland
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13
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Karakochuk CD, Henderson AM, Samson KLI, Aljaadi AM, Devlin AM, Becquey E, Wirth JP, Rohner F. Comparison of a New Multiplex Immunoassay for Measurement of Ferritin, Soluble Transferrin Receptor, Retinol-Binding Protein, C-Reactive Protein and α¹-Acid-glycoprotein Concentrations against a Widely-Used s-ELISA Method. Diagnostics (Basel) 2018; 8:E13. [PMID: 29393894 PMCID: PMC5871996 DOI: 10.3390/diagnostics8010013] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2018] [Revised: 01/26/2018] [Accepted: 01/31/2018] [Indexed: 01/30/2023] Open
Abstract
Recently, a multiplex ELISA (Quansys Biosciences) was developed that measures ferritin, soluble transferrin receptor (sTfR), retinol-binding protein (RBP), C-reactive protein (CRP), α¹-acid glycoprotein (AGP), thyroglobulin, and histidine-rich protein 2. Our primary aim was to conduct a method-comparison study to compare five biomarkers (ferritin, sTfR, RBP, CRP, and AGP) measured with the Quansys assay and a widely-used s-ELISA (VitMin Lab, Willstaett, Germany) with use of serum samples from 180 women and children from Burkina Faso, Cambodia, and Malaysia. Bias and concordance were used to describe the agreement in values measured by the two methods. We observed poor overall agreement between the methods, both with regard to biomarker concentrations and deficiency prevalence estimates. Several measurements were outside of the limit of detection with use of the Quansys ELISA (total n = 42 for ferritin, n = 2 for sTfR, n = 0 for AGP, n = 5 for CRP, n = 22 for RBP), limiting our ability to interpret assay findings. Although the Quansys ELISA has great potential to simplify laboratory analysis of key nutritional and inflammation biomarkers, there are some weaknesses in the procedures. Overall, we found poor comparability of results between methods. Besides addressing procedural issues, additional validation of the Quansys against a gold standard method is warranted for future research.
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Affiliation(s)
- Crystal D Karakochuk
- Food, Nutrition, and Health, University of British Columbia, Vancouver, BC V6T 1Z4, Canada.
- BC Children's Hospital Research Institute, Vancouver, BC V5Z 4H4, Canada.
| | - Amanda M Henderson
- BC Children's Hospital Research Institute, Vancouver, BC V5Z 4H4, Canada.
- Department of Paediatrics, University of British Columbia, Vancouver, BC V6H 3V4, Canada.
| | - Kaitlyn L I Samson
- Food, Nutrition, and Health, University of British Columbia, Vancouver, BC V6T 1Z4, Canada.
- BC Children's Hospital Research Institute, Vancouver, BC V5Z 4H4, Canada.
| | - Abeer M Aljaadi
- Food, Nutrition, and Health, University of British Columbia, Vancouver, BC V6T 1Z4, Canada.
- BC Children's Hospital Research Institute, Vancouver, BC V5Z 4H4, Canada.
| | - Angela M Devlin
- BC Children's Hospital Research Institute, Vancouver, BC V5Z 4H4, Canada.
- Department of Paediatrics, University of British Columbia, Vancouver, BC V6H 3V4, Canada.
| | - Elodie Becquey
- International Food Policy Research Institute, Washington, DC 20005, USA.
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14
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Brindle E, Lillis L, Barney R, Hess SY, Wessells KR, Ouédraogo CT, Stinca S, Kalnoky M, Peck R, Tyler A, Lyman C, Boyle DS. Simultaneous assessment of iodine, iron, vitamin A, malarial antigenemia, and inflammation status biomarkers via a multiplex immunoassay method on a population of pregnant women from Niger. PLoS One 2017; 12:e0185868. [PMID: 28982133 PMCID: PMC5628875 DOI: 10.1371/journal.pone.0185868] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2017] [Accepted: 09/20/2017] [Indexed: 11/24/2022] Open
Abstract
Deficiencies of vitamin A, iron, and iodine are major public health concerns in many low- and middle-income countries, but information on their status in populations is often lacking due to high costs and logistical challenges associated with assessing micronutrient status. Accurate, user-friendly, and low-cost analytical tools are needed to allow large-scale population surveys on micronutrient status. We present the expansion of a 7-plex protein microarray tool for the simultaneous measurement of up to seven biomarkers with relevance to the assessment of the key micronutrients iron, iodine, and vitamin A, and inflammation and malaria biomarkers: α-1-acid glycoprotein, C-reactive protein, ferritin, retinol binding protein 4, soluble transferrin receptor, thyroglobulin, and histidine-rich protein II. Assay performance was assessed using international reference standards and then verified by comparing the multiplexed and conventional immunoassay results on a training panel of plasma samples collected from US adults. These data were used to assign nominal concentrations to the calibrators of the assay to further improve performance which was then assessed by interrogating plasma samples from a cohort of pregnant women from Niger. The correlation between assays for each biomarker measured from this cohort was typically good, with the exception of thyroglobulin, and the sensitivity ranged from 74% to 93%, and specificity from 81% to 98%. The 7-Plex micronutrient assay has the potential for use as an affordable tool for population surveillance of vitamin A, iron, and iodine deficiencies as well as falciparum malarial parasitemia infectivity and inflammation. The assay is easy-to-use, requires minimal sample volume, and is scalable, rapid, and accurate—needing only a low-cost reader and basic equipment present in most reference laboratory settings and so may be employed by low and middle income countries for micronutrient surveillance to inform on status in key populations. Micronutrient deficiencies including iron, iodine, and vitamin A affect a significant portion of the world’s population. Efforts to assess the prevalence of these deficiencies in vulnerable populations are challenging, partly due to measurement tools that are inadequate for assessing multiple micronutrients in large-scale population surveys. We have developed a 7-plex immunoassay for the simultaneous measurement of seven biomarkers relevant to assessing iodine, iron, and vitamin A status, inflammation and Plasmodium falciparum parasitemia by measuring levels of thyroglobulin, ferritin, soluble transferrin receptor, retinol binding protein 4, α-1-acid glycoprotein, C-reactive protein, and histidine-rich protein II. This 7-plex immunoassay technique has potential as a rapid and effective tool for use in large-scale surveys and assessments of nutrition intervention programs in low- and middle-income countries.
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Affiliation(s)
- Eleanor Brindle
- Center for Studies in Demography and Ecology, University of Washington, Seattle, WA, United States of America
| | | | | | - Sonja Y. Hess
- Program in International and Community Nutrition, Department of Nutrition, University of California, Davis, CA, United States of America
| | - K. Ryan Wessells
- Program in International and Community Nutrition, Department of Nutrition, University of California, Davis, CA, United States of America
| | - Césaire T. Ouédraogo
- Program in International and Community Nutrition, Department of Nutrition, University of California, Davis, CA, United States of America
- Helen Keller International, Niamey, Niger
| | - Sara Stinca
- Laboratory of Human Nutrition, Swiss Federal Institute of Technology, Zurich, Switzerland
| | | | - Roger Peck
- PATH, Seattle, WA, United States of America
| | - Abby Tyler
- Quansys Biosciences, Logan, Utah, United States of America
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15
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Lee S, Srinivasan B, Vemulapati S, Mehta S, Erickson D. Personalized nutrition diagnostics at the point-of-need. LAB ON A CHIP 2016; 16:2408-2417. [PMID: 27272753 DOI: 10.1039/c6lc00393a] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Micronutrient deficiency is widespread and negatively impacts morbidity, mortality, and quality of life globally. On-going advancements in nutritional biomarker discovery are enabling objective and accurate assessment of an individual's micronutrient and broader nutritional status. The vast majority of such assessment however still needs to be conducted in traditional centralized laboratory facilities which are not readily accessible in terms of cost and time in both the developed and developing countries. Lab-on-a-chip (LOC) technologies are enabling an increasing number of biochemical reactions at the point-of-need (PON) settings, and can significantly improve the current predicament in nutrition diagnostics by allowing rapid evaluation of one's nutritional status and providing an easy feedback mechanism for tracking changes in diet or supplementation. We believe that nutrition diagnostics represents a particularly appealing opportunity over other PON applications for two reasons: (1) healthy ranges for many micronutrients are well defined which allows for an unbiased diagnosis, and (2) many deficiencies can be reversed through changes in diet or supplementation before they become severe. In this paper, we provide background on nutritional biomarkers used in nutrition diagnostics and review the emerging technologies that exploit them at the point-of-need.
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Affiliation(s)
- Seoho Lee
- Sibley School of Mechanical and Aerospace Engineering, Cornell University, Ithaca, NY 14853, USA.
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16
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Konopińska K, Pietrzak M, Mazur R, Malinowska E. Analytical characterization of IgG–cTpp and IgG–Mn-cTpp conjugates. J PORPHYR PHTHALOCYA 2016. [DOI: 10.1142/s1088424615500984] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Herein, the conjugation of carboxylated tetraphenylporphyrin or its derivative containing manganese cation and model protein — immunoglobulin G is presented. The obtained IgG–cTpp and IgG–Mn-cTpp conjugates were subsequently used for model immunoassays construction. The IgG–cTpp formation was confirmed using size-exclusion chromatography. Thanks to the unique properties of applied labels the assay analysis was carried out with both spectrophotometric and spectrofluorimetric detection. The assays were performed creating semi-quantitative detection system using 96-well plates. The incubation time, ensuring full saturation of the surface with secondary antibodies was also optimized. Moreover, in the case of IgG–Mn-cTpp conjugates we present the possibility of both direct and indirect determination of the label, the latter based on the catalytic activity of Mn-cTpp, which allows for amplification of the measured signal. We proved that both cTpp and Mn-cTpp may be successfully used for protein labeling and serve as universal tracers for various formats of affinity assays and sensors.
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Affiliation(s)
- Kamila Konopińska
- Department of Microbioanalytics, Faculty of Chemistry, Warsaw University of Technology, Noakowskiego 3, 00-664 Warsaw, Poland
| | - Mariusz Pietrzak
- Department of Microbioanalytics, Faculty of Chemistry, Warsaw University of Technology, Noakowskiego 3, 00-664 Warsaw, Poland
| | - Radosław Mazur
- Department of Metabolic Regulation, Institute of Biochemistry, Faculty of Biology, University of Warsaw, Miecznikowa 1, 02-096 Warsaw, Poland
| | - Elżbieta Malinowska
- Department of Microbioanalytics, Faculty of Chemistry, Warsaw University of Technology, Noakowskiego 3, 00-664 Warsaw, Poland
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