Schematic illustrating the plasma collection disc in operation.

The schematic illustrates a single PCD. Photos on the left show the PCD with the the filter disc placed on a manifold for multiple samples and the addition of 35 μL of whole blood to each disc (top), a PDC detail view prior to whole blood being added (middle), and the discs after blood has been absorbed and finally the plasma collection disc exposed after the whole blood treated filter has been removed (bottom). The disc is removed with sterile forceps and is ready for use or can be stored until required.</p

Summary statistics and cross-laboratory coefficients of variation (CV) for plasma, DBS and PCD.

Summary statistics and cross-laboratory coefficients of variation (CV) for plasma, DBS and PCD.</p

Fig 3 -

A. Lin’s concordance correlation coefficient (CCC) plots comparing the analyte measurements in paired wet plasma (x-axes) and DBS samples (y-axes). AGP, α-1-acid glycoprotein; CRP, C-reactive protein; FER, ferritin; HRP2, histidine rich protein 2; RBP4, retinol binding protein 4; sTfR, soluble transferrin receptor; Tg, thyroglobulin; DBS, dried blood spot; rho_c, CCC. B, Lin’s CCC plots comparing the analyte measurements in paired wet plasma (x-axes) and the adjusted PCD (y-axes). AGP, α-1-acid glycoprotein; CRP, C-reactive protein; FER, ferritin; HRP2, histidine rich protein 2; RBP4, retinol binding protein 4; sTfR, soluble transferrin receptor; Tg, thyroglobulin; DBS, dried blood spot; rho_c, CCC.</p

The comparison of results for plasma, DBS and the volume adjusted PCD eluates using <i>R</i>_<i>s</i> and recovery of expected plasma values.

The comparison of results for plasma, DBS and the volume adjusted PCD eluates using Rs and recovery of expected plasma values.</p

Sample panels and experiment design.

Sample panels and experiment design.</p

Fig 4 -

A. Bland Altman plots of the difference in results derived from wet plasma versus DBS types measured using the 7-plex assay. Average of the wet plasma and dry sample type (x-axes) are plotted against the difference between measurements from the 7-Plex assay for paired wet plasma and dry sample types (y-axes). B. Bland Altman plots of the difference in results derived from wet plasma versus the adjusted PCD. For both Figures, the horizontal lines indicate line of perfect agreement (green), mean (purple), and ± 2standard deviations of the difference (red). AGP, α-1-acid glycoprotein; CRP, C-reactive protein; FER, ferritin; HRP2, histidine rich protein 2; RBP4, retinol binding protein 4; sTfR, soluble transferrin receptor; Tg, thyroglobulin; DBS, dried blood spot.</p

Contrived blood samples spiked with a range of elevated levels of AGP, CRP, HRP2 and sTfR.

Contrived blood samples spiked with a range of elevated levels of AGP, CRP, HRP2 and sTfR.</p

Example soft cassette tests run with standard wick (Ahlstrom 243) or compressed cellulose wick.

<p>All tests were run with positive-spiked blood samples. Vivid samples shown below were run with 5 µl of blood and Cytosep samples shown were run with 30 µl of blood.</p

Fraction of tests that failed due to blood on membrane after dry.

<p>Tests that had blood on the membranes after the test was dry were counted as failed tests. This failure rate is shown as a function of the volume, blood filter, and wick material. A minimum of 10 tests were run for each condition shown.</p

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

<div><p>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 <i>Plasmodium falciparum</i> 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.</p></div