Research data supporting "Gene to Diagnostic: Self immobilizing protein for silica microparticle biosensor, modelled with sarcosine oxidase"

Raw analytical data supporting manuscript, including fluorescent data, laser scattering, protein sequences, and raw data belonging to the graphs in the publication. Abstract of manuscript: A rational design approach is proposed for a multifunctional enzyme reagent for point-of-care diagnostics. The biomaterial reduces downstream isolation steps and eliminates immobilization coupling chemicals for integration in a diagnostic platform. Fusion con-structs combined the central functional assay protein (e.g. monomeric sarcosine oxidase, mSOx, horseradish peroxidase, HRP), a visualizing protein (e.g. mCherry) and an in-built immobilization peptide (e.g. R5). Monitoring protein expression in E.coli was facilitated by following the increase in mCherry fluorescence, which could be matched to a color card, indicating when good protein expression has occurred. The R5 peptide (SSKKSGSYSGSKGSKRRIL) provided inbuilt affinity for silica and an immobilization capability for a silica based diagnostic, without requiring additional chemical coupling reagents. Silica particles extracted from beach sand were used to collect protein from crude protein extract with 85-95% selective uptake. The silica immobilized R5 pro-teins were stable for more than 2 months at room temperature. The Km for the silica-R52-mCh-mSOx-R5-6H was 16.5±0.9mM (com-pared with 16.5±0.4 mM, 16.3±0.3 mM, and 16.1±0.4 mM for R52-mCh-mSOx-R5-6H, mSOx-R5-6H and mSOx-6H respectively in solution). The use of the “silica-enzymes” in sarcosine and peroxide assays was shown, and a design using particle sedimentation through the sample was examined. Using shadowgraphy and particle image velocimetry the particle trajectory through the sample was mapped and an hourglass design with a narrow waist shown to give good control of particle position. The hourglass biosensor was demonstrated for sarcosine assay in the clinically useful range of 2.5 to 10 µM in both a dynamic and end point measurement regime.