Porous membrane strip microsampling: a dried biofluid collection format and application for quantitative enzyme immunoassay
Applicability of a new and simple membrane-strip microsampling format for the analysis of human blood serum in a strip-dried form for the presence of a range of model low and high molecular weight analytes by ELISA was demonstrated. Biofluid was applied onto a narrow strip of porous membrane, dried and analysed using a square piece of membrane (0.5 × 0.5 cm). An antigen distribution along a sampling strip and storage stability in strip-dried human serum samples were investigated in a quantitative assay. It was demonstrated that thyroxine, progesterone, thyroglobulin, prostate specific antigen and antibodies (IgG) against H. pylori were stable on the strip-dried sample for at least a week at ambient temperature and 37 °C. For all antigens, the concordance of the data obtained for liquid and strip-dried serum samples was observed (Bland–Altman data analysis). The proposed new strip microsampling format provides volumetric sample collection and can find application in quantitative immunoassays, for instance, in ELISA.