title: Nanocrystalline diamond sensor targeted for selective CRP detection: an ATR-FTIR spectroscopy study.
abstract: Protein immobilization on functionalized fluorine-terminated nanocrystalline (NCD) films was studied by attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy using an immobilization protocol developed to specifically bind C-reactive protein (CRP). Using an ATR-FTIR spectroscopy method employing a force-controlled anvil-type configuration, three critical steps of the ex situ CRP immobilization were analyzed. First, the NCD surface was passivated by deposition of a copolymer layer consisting of polyethylene oxide and polypropylene oxide. Second, a synthetic modified polypeptide binder with high affinity to CRP was covalently attached to the polymeric film. Third, CRP dissolved in aqueous buffer in concentrations of 10-20 μg/mL was added on the functionalized NCD surface. Both the amide I and II bands, due to the polypeptide binder and CRP, were clearly observed in ATR-FTIR spectra. CRP amide I bands were extracted from difference spectra and yielded bands that agreed well with the reported amide I band of free (non-bonded) CRP in solution. Thus, our results show that CRP retains its secondary structure when it is attached to the polypeptide binders. Compared to previous IR studies of CRP in solution, about 200 times lower concentration was applied in the present study. Graphical Abstract Direct non-destructive ATR-FTIR analysis of C-reactive protein (CRP) selectively bound to functionalized nanocrystalline diamond (NCD) sensor surface.
authors.affiliation: CBRN Defence and Security, FOI Swedish Defence Research Agency, 901 82, Umeå, Sweden. perola.andersson@foi.se.|Department of Engineering Sciences, Uppsala University, P.O. Box 534, 751 21, Uppsala, Sweden. perola.andersson@foi.se.|Molecular Fingerprint Sweden AB, Eksätravägen 130, 756 55, Uppsala, Sweden. perola.andersson@foi.se.
authors.forename: Per Ola
authors.initials: PO
authors.lastname: Andersson
authors.affiliation: Department of Engineering Sciences, Uppsala University, P.O. Box 534, 751 21, Uppsala, Sweden.
authors.forename: Pernilla
authors.initials: P
authors.lastname: Viberg
authors.affiliation: Department of Engineering Sciences, Uppsala University, P.O. Box 534, 751 21, Uppsala, Sweden.
authors.forename: Pontus
authors.initials: P
authors.lastname: Forsberg
authors.affiliation: Department of Engineering Sciences, Uppsala University, P.O. Box 534, 751 21, Uppsala, Sweden.|Molecular Fingerprint Sweden AB, Eksätravägen 130, 756 55, Uppsala, Sweden.
authors.forename: Fredrik
authors.initials: F
authors.lastname: Nikolajeff
authors.affiliation: Department of Engineering Sciences, Uppsala University, P.O. Box 534, 751 21, Uppsala, Sweden.|Molecular Fingerprint Sweden AB, Eksätravägen 130, 756 55, Uppsala, Sweden.
authors.forename: Lars
authors.initials: L
authors.lastname: Österlund
authors.affiliation: Department of Engineering Sciences, Uppsala University, P.O. Box 534, 751 21, Uppsala, Sweden.|Molecular Fingerprint Sweden AB, Eksätravägen 130, 756 55, Uppsala, Sweden.
authors.forename: Mikael
authors.initials: M
authors.lastname: Karlsson
mesh_terms: D015374:Biosensing Techniques; D002097:C-Reactive Protein / Q000032:analysis*; D003460:Crystallization; D018130:Diamond; D049329:Nanostructures; D017550:Spectroscopy, Fourier Transform Infrared / Q000379:methods*
chemical_list: D018130:Diamond; D002097:C-Reactive Protein
keywords: ATR-FTIR; Biosensor; CRP; Infrared spectroscopy; Nanocrystalline diamond; Protein binders