Abstract
Paper and cellulosic films are used in many designs of low-cost diagnostics such as paper-based blood grouping devices. A major issue limiting their commercialization is the short stability of the functional biomolecules. To address this problem, the effect of relative humidity (RH) and bovine serum albumin (BSA) on the antibody bioactivity and the surface chemical composition of a paper blood typing biodiagnostic were studied. An IgM blood typing antibody was physisorbed from solution onto paper - with or without BSA pretreatment, and aged for periods up to 9 weeks under various conditions with a series of RH. The blood typing efficiency of the antibodies and the substrate surface chemical composition were analyzed by image analysis and X-ray photoelectron spectroscopy (XPS), respectively. This study tests two hypotheses. The first is that the hydroxyl groups in paper promote antibody denaturation on paper; the second hypothesis is that proteins such as BSA can partially block the hydroxyl groups within paper, thus preserving antibody bioactivity. Results show that high RH is detrimental to antibody longevity on paper, while BSA can block hydroxyl groups and prolong antibody longevity by almost an order of magnitude—regardless of humidity. This study opens up new engineering concepts to develop robust and marketable paper diagnostics. The simplest is to store paper and antibody based diagnostics in moisture proof packages.
Highlights
Paper and cellulosic films have emerged as powerful platforms to engineer biomedical diagnostics for detecting blood glucose, blood groups, and pathogens (Pohanka et al, 2007)
Anti-A IgM blood typing antibodies were physisorbed from solution onto a paper towel, pretreated or not with bovine serum albumin (BSA), and aged up to 9 weeks under various relative humidity (RH)
The antibody bioactivity over time and the chemical composition of the bioactive paper were measured by image analysis and X-ray photoelectron spectroscopy (XPS), respectively
Summary
Paper and cellulosic films have emerged as powerful platforms to engineer biomedical diagnostics for detecting blood glucose, blood groups, and pathogens (Pohanka et al, 2007). Major obstacles, including sensor instability and poor longevity, have restricted paper biosensors commercialization. Paper-based blood grouping devices containing blood grouping antibodies on paper provide reproducible results for only up to 1 month (Guan et al, 2014). Paper diagnostics often show poor reproducibility in quantification tested months apart (Delaney et al, 2011). These drawbacks are believed to result from the antibody instability. The mechanism by which antibodies physisorbed on paper lose their bioactivity is poorly understood. Unknown is whether paper can be modified to stabilize physisorbed antibodies. Efficient commercialization of paper biosensors requires a robust understanding of the mechanisms behind antibody functionality and stability loss
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