In this Article, we present a new strategy for preparing an antihemoglobin biointerface on cellulose. The preparation method is based on functionalization of the cellulose surface by the irreversible adsorption of CMC, followed by covalent linking of antibodies to CMC. This would provide the means for affordable and stable cellulose-based biointerfaces for immunoassays. The preparation and characterization of the biointerface were studied on Langmuir-Schaefer cellulose model surfaces in real time using the quartz crystal microbalance with dissipation and surface plasmon resonance techniques. The stable attachment of antihemoglobin to adsorbed CMC was achieved, and a linear calibration of hemoglobin was obtained. CMC modification was also observed to prevent nonspecific protein adsorption. The antihemoglobin-CMC surface regenerated well, enabling repeated immunodetection cycles of hemoglobin on the same surface.
Morphine was used as a model analyte to examine the possibility of using cellulose, physically modified by papermaking and converting techniques, as a capillary matrix in a lateral flow type of diagnostic assay. This research was directed toward low-cost, disposable, and portable paper-based diagnostics, with the aim of addressing the analytical performance of paper as a substrate in the analysis for drugs of abuse. Antibody Fab fragments were used as sensing molecules, and gold nanoparticle detection was employed. Inkjet printing was used to pattern sensing biomolecules as detection zones on paper. To validate the usefulness of paper as a diagnostic platform, the principle of a direct sandwich assay, based on immunocomplex formation between morphine and the anti-morphine Fab fragment and detection of the formed immunocomplex by another Fab fragment, was implemented. Results were compared with that achieved by using nitrocellulose as a reference material. Possible interfering from the sample matrix on assay quality was investigated with spiked oral fluid samples. Under optimized conditions, a visually assessed limit of detection for the sandwich assay was 1 ng/mL, indicating that the paper-based test devices developed in this work can perform screening for drugs of abuse and can fulfill the requirement for a sensitive assay in diagnostically relevant ranges.
Syrup with optimized flavor was produced from birch (Betula pubescens Ehrh.) sap (1°Brix) by reverse osmosis and evaporation under reduced pressure. The soluble solids content (70-75°Brix) gave an adequate consistency to the syrup, which needed a low-heat treatment to obtain the desired color (IUâ bout 3.5 cm-1 °Brix-1) and flavor. Excess heating produced a dark brown color and a burned flavor. More than 90% (w/w) of the dry matter consisted of sugars (48% glucose, 41% fructose, 0.6% sucrose, 0.5% galactose), 3.1% malic acid, 2.8% ash, and 0.4% free amino acids. The syrup varied between pH 5.6 and 6.5, showing a decreasing tendency when heated.Birch Sap and Syrup. The birch sap of B. pubescens Ehrh. from Katiskoski, Finland (61°6 0' N, 24°30' E), was
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