Analysis of Nitrocellulose-Based Solid-State Calibration Standards for Point-of-Care (PoC) Fluorometers

This study presents an analysis of nitrocellulosebased solid-state calibration standards for point-of-care (POC) fluorometers. Our findings show that the manual assembly process introduces significant variations in the alignment/offset of printed lines with respect to the optical aperture. A Claremont BioSolutions and BioDot automated dispenser were compared to determine efficacy in producing high-quality calibration standards. Qualitative analysis of line morphology shows less pronounced irregularities in lines printed by the BioDot. The BioDot also demonstrated significantly lower variation in the width of printed lines, with a CV of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">${6. 4 \%}$</tex> compared to the Claremont's <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">${2 7. 0 \%}$</tex>. However, fluorescence intensity measurements using a POC fluorometer revealed a mean inter-sample CV of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">${1 5. 0 \%}$</tex> and <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">${1 4. 2 \%}$</tex> for the Claremont and BioDot, respectively. Direct and indirect fluorophore immobilization methods were compared. The results indicated that the direct method is a viable approach, but the indirect method presents challenges with increased background and fluorophore depletion, rendering it unsuitable for calibration standard production. Clinical relevance-This work investigates the efficacy of nitrocellulose-based solid-state standards for calibrating POC fluorometers, which are essential for ensuring accurate diagnosis and screening of patient samples.