Ago Mrsa (ab), Trine Grønhaug Halvorsen (a) and Léon Reubsaet (a) a University of Oslo, Department of Pharmacy, Oslo, Norway b Norwegian Defense Research Establishment, Kjeller, Norway Email: ago.mrsa@ffi.no
The demand for biomarker analysis is rising to detect and treat diseases that need frequent follow-up. Microsampling techniques such as dried blood spots, offer several benefits, such as increased patient compliance, ease of use and low cost. However, due to the low sample volume (≥50µL), analysis of compounds such as protein biomarkers can be challenging. In 2018, the concept of smart sampling was introduced to reduce processing time and help standardize the method by integrating sample preparation into the sampler.
This work presents a paper-based antibody smart sampler used for selective capture of the model protein human chorionic gonadotropin (hCG). This work has aimed to bring the idea of smart sampling from the research lab a step closer to real-world application.
Manufacturing of the smart sampler was achieved through the chemical modification of cellulose using divinyl sulfone, enabling covalent binding of antibodies to the paper by a one-step reaction. This antibody-based sampler has demonstrated strong performance and has thus been validated for hCG in human serum using EMA’s ICH M10 guidelines on bioanalytical methods. Calibration curves in the range of 0.5 ng/mL to 75 ng/mL all display excellent linearity (r2 ≥ 0.995) with accuracy and precision for inter day (n=3) and intra day (n=5) falling well within the guideline’s acceptable limits. Comparison of the Smart sampling method and a commercial ELICA method used by thew Norwegian Doping Control Laboratory for hCG determination in serum has been done for a set of 21 unknown samples. Investigation using different matrices highlighted some challenges regarding whole blood, as removing enough hemoglobin proved difficult resulting in complete loss of analyte signal. To address this, a new two-in-one sampler was developed, integrating plasma separation and immunocapture in the same sampling device. This design achieved efficient red blood cell removal and improved sample cleanup without analyte loss, significantly enhancing performance for whole blood applications of smart samplers.