title: Proton-functionalized two-dimensional graphitic carbon nitride nanosheet: an excellent metal-/label-free biosensing platform.
abstract: Ultrathin graphitic carbon nitride (g-C3N4) nanosheets, due to their interesting two-dimensional graphene-like structure and unique physicochemical properties, have attracted great research attention recently. Here, a new approach is developed to prepare, for the first time, proton-functionalized ultrathin g-C3N4 nanosheets by sonication-exfoliation of bulk g-C3N4 under an acid condition. This method not only reduces the exfoliation time from more than 10 h to 2 h, but also endows the nanosheets with positive charges. Besides retaining the properties of g-C3N4, the obtained nanosheets with the thickness of 2-4 nm (i.e., 6-12 atomic monolayers) also exhibit large specific surface area of 305 m(2) g(-1), enhanced fluorescence intensity, and excellent water dispersion stability due to their surface protonation and ultrathin morphology. The well-dispersed protonated g-C3N4 nanosheets are able to interact with negatively charged heparin, which results in the quenching of g-C3N4 fluorescence. A highly sensitive and highly selective heparin sensing platform based on protonated g-C3N4 nanosheets is established. This metal-free and fluorophore label-free system can reach the lowest heparin detection limit of 18 ng mL(-1).
authors.affiliation: School of Chemical Engineering, The University of Adelaide, Adelaide, SA, 5005, Australia.
authors.forename: Tian Yi
authors.initials: TY
authors.lastname: Ma
authors.forename: Youhong
authors.initials: Y
authors.lastname: Tang
authors.forename: Sheng
authors.initials: S
authors.lastname: Dai
authors.forename: Shi Zhang
authors.initials: SZ
authors.lastname: Qiao
mesh_terms: D000818:Animals; D015374:Biosensing Techniques / Q000295:instrumentation / Q000379:methods; D020099:Coated Materials, Biocompatible / Q000138:chemical synthesis* / Q000737:chemistry; D006108:Graphite / Q000737:chemistry*; D006493:Heparin / Q000032:analysis / Q000097:blood; D006801:Humans; D057230:Limit of Detection; D008422:Materials Testing; D008670:Metals; D049329:Nanostructures / Q000737:chemistry*; D009570:Nitriles / Q000138:chemical synthesis / Q000737:chemistry*; D011522:Protons; D013552:Swine
chemical_list: D020099:Coated Materials, Biocompatible; D008670:Metals; D009570:Nitriles; D011522:Protons; C011206:cyanogen; D006108:Graphite; D006493:Heparin
keywords: biosensing; carbon nitride; fluorescence; heparin; nanosheets