BACKGROUND:A life-threatening anaphylactic shock can occur if a patient with undiagnosed immunoglobulin A (IgA) deficiency (i.e., IgA levels <500 ng/mL) receives IgA-containing blood, hence the need for a rapid, point-of-care (POC) method for IgA deficiency screening. Enzyme-linked immunosorbent assay (ELISA) is routinely used to detect IgA, but this method requires trained specialists and ≥24 h to obtain a result. We developed a surface plasmon resonance (SPR)-based protocol to identify IgA-deficient patients or donors within 1 h. MATERIALS AND METHODS:The SPR sensor relies on the detection of IgAs captured by primary antibodies adsorbed on the SPR chip and quantified with secondary antibodies. The sensor was calibrated from 0 to 2000 ng/mL in buffer, IgA-depleted human serum, and plasma samples from IgA-deficient individuals. A critical concentration of 500 ng/mL was set for IgA deficiency. The optimized sensor was then tested on eight plasma samples with known IgA status (determined by ELISA), including five with IgA deficiency and three with normal IgA levels. RESULTS:The limit of detection was estimated at 30 ng/mL in buffer and 400 ng/mL in diluted plasma. The results obtained fully agreed with ELISA among the eight plasma samples tested. The protocol distinguished IgA-deficient from normal samples, even for samples with an IgA concentration closer to critical concentration. DISCUSSION:In conclusion, we developed a reliable POC assay for the quantification of IgA in plasma. This test may permit POC testing at blood drives and centralized centers to maintain reserves of IgA-deficient blood and in-hospital testing of blood recipients.

Health-care-associated infections (HAIs) can occur if a contaminated product bypasses current tests and prophylactic measures. These contaminations may be missed due to low bacterial loads or the presence of adhered biofilms. Antibacterial coatings applied inside blood storage bags or onto medical devices are promising to further reduce the residual risk of HAIs. The aim of this study was to optimize the antibacterial efficacy of a polymer — polydopamine — as a potential material for the prevention of transfusion-transmitted bacterial infections. When varying the concentration of dopamine monomers (1-3 mg/mL), the sample position (horizontal vs vertical), the stirring speed (0–90 RPM) and the reaction time (0.5 – 24 h), the morphology and wettability of the coatings were modified as determined by UV–visible (absorbance 0.013 – 0.562 at 320 nm), wettability (contact angle 35 – 61 °C) and atomic force microscopy measurements (total roughness 6 – 140 nm). The resulting cytotoxic (< 6%) and antibacterial behaviors (< 90 – 99% bacterial reduction) of the coatings were determined using ISO-10993–5 and ISO 22196 standardization. Coatings with good thickness and roughness had optimal antibacterial effects against Staphylococcus aureus (1.6 ± 0.4 log reduction), although minimal reduction was measured against Escherichia coli (0.05 log reduction). The antibacterial efficacy of polydopamine appears to be linked to its thickness and roughness, two parameters that may affect the surface wettability and, in turn, bacterial adhesion. Based on these results, polydopamine could be employed to help limit HAIs, although its antibacterial properties need to be further improved depending on the nature of bacteria and the requirements of the applications.

Diffuse reflectance spectroscopy (DRS) is a promising technique for non-invasive monitoring of tissue oxygen saturation (StO2). However, the interpretation of DRS data can be complicated by the presence of confounding factors such as the volume fraction of blood, tissue scattering, and lipid content which both absorb and scatter. Principal component analysis (PCA) is a multivariate statistical method that can help overcome these challenges by extracting relevant information from complex datasets and providing new dimensions used to estimate parameters such as concentrations. In this study, we present a PCA-based algorithm for estimating retinal StO2 from DRS measurements. We evaluated the performance of our algorithm using simulated data and experimental measurements on a retinal tissue phantom model. Our results show that the PCA-based algorithm can estimate the value of StO2 with a root-mean-square error of 6.38% in the presence of confounding factors. Our study demonstrates the potential of PCA as a powerful tool for extracting the concentration of components from complex DRS.

TransfusionVolume 63, Issue S5 p. 52A-52A SUPPLEMENT ARTICLE OA3-AM23-SN-05 | Ferritin Determination in Blood Using a Point-of-Care Surface Plasmon Resonance Sensor C. Dubois, C. Dubois Montreal UniversitySearch for more papers by this authorJ. Robidoux, J. Robidoux Héma-QuébecSearch for more papers by this authorJ. Masson, J. Masson Montreal UniversitySearch for more papers by this authorD. Brouard, D. Brouard Héma-QuébecSearch for more papers by this author C. Dubois, C. Dubois Montreal UniversitySearch for more papers by this authorJ. Robidoux, J. Robidoux Héma-QuébecSearch for more papers by this authorJ. Masson, J. Masson Montreal UniversitySearch for more papers by this authorD. Brouard, D. Brouard Héma-QuébecSearch for more papers by this author First published: 12 October 2023 https://doi.org/10.1111/trf.54_17554Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onEmailFacebookTwitterLinkedInRedditWechat No abstract is available for this article. Volume63, IssueS5October 2023Pages 52A-52A RelatedInformation

Ocular oximetry, in which blood oxygen saturation is evaluated in retinal tissues, is a promising technique for the prevention, diagnosis and management of many diseases and conditions. However, the development of new tools for evaluating oxygen saturation in the eye fundus has often been limited by the lack of reference tools or techniques for such measurements. In this study, we describe a two-step validation method. The impact of scattering, blood volume fraction and lens yellowing on the oximetry model is investigated using a tissue phantom, while a Monte Carlo model of the light propagation in the eye fundus is used to study the effect of the fundus layered-structure. With this method, we were able to assess the performance of an ocular oximetry technique in the presence of confounding factors and to quantify the impact of the choroidal circulation on the accuracy of the measurements. The presented strategy will be useful to anyone involved in studies based on the eye fundus diffuse reflectance.

We present an oximetry validation method, combining phantom and Monte Carlo simulation, that allows to investigate the robustness to light scattering, hemoglobin concentrations and lens yellowing; and study the impact of the fundus layered structure.

BACKGROUND Great deformability allows red blood cells (RBCs) to flow through narrow capillaries in tissues. A number of microfluidic devices with capillary‐like microchannels have been developed to monitor storage‐related impairment of RBC deformability during blood banking operations. This proof‐of‐concept study describes a new method to standardize and improve reproducibility of the RBC deformability measurements using one of these devices. STUDY DESIGN AND METHODS The rate of RBC flow through the microfluidic capillary network of the microvascular analyzer (MVA) device made of polydimethylsiloxane was measured to assess RBC deformability. A suspension of microbeads in a solution of glycerol in phosphate‐buffered saline was developed to be used as an internal flow rate reference alongside RBC samples in the same device. RBC deformability and other in vitro quality markers were assessed weekly in six leukoreduced RBC concentrates (RCCs) dispersed in saline‐adenine‐glucose‐mannitol additive solution and stored over 42 days at 4°C. RESULTS The use of flow reference reduced device‐to‐device measurement variability from 10% to 2%. Repeated‐measure analysis using the generalized estimating equation (GEE) method showed a significant monotonic decrease in relative RBC flow rate with storage from Week 0. By the end of storage, relative RBC flow rate decreased by 22 ± 6% on average. CONCLUSIONS The suspension of microbeads was successfully used as a flow reference to increase reproducibility of RBC deformability measurements using the MVA. Deformability results suggest an early and late aging phase for stored RCCs, with significant decreases between successive weeks suggesting a highly sensitive measurement method.