title: Ti(IV) carrying polydopamine-coated, monodisperse-porous SiO2microspheres with stable magnetic properties for highly selective enrichment of phosphopeptides.
abstract: A marked decrease in the saturation magnetization by the formation of functional shells around the magnetic core is an important disadvantage of magnetic core-shell nanoparticles. Another drawback of Ti(IV)-functionalized immobilized metal affinity chromatography (IMAC) sorbents is the acidic character of the binding medium used for Ti4+attachment onto composite magnetic nanoparticles, which causes an additional decrease in the saturation magnetization owing to the chemical interaction between the acidic moiety and the magnetic core. An IMAC sorbent in the form of magnetic microspheres with superior and stable magnetic properties with respect to magnetic core-shell nanoparticles was designed for phosphopeptide enrichment. Magnetic, monodisperse-porous silica microspheres (MagSiO2) 6μm in size were synthesized by a new staged-shape template hydrolysis-condensation protocol. A porous-silica shell layer was generated around the microspheres to protect the magnetic core from the acidic medium during Ti4+attachment (MagSiO2@SiO2). The MagSiO2@SiO2microspheres were coated with a polydopamine shell (MagSiO2@SiO2@PDA) and Ti4+was attached onto the composite microspheres (MagSiO2@SiO2@PDA@Ti(IV)). Formation of the PDA layer and Ti4+attachment did not cause any significant decrease in the saturation magnetization. The platform exhibited excellent performance for phosphopeptide enrichment from the digests of phosphorylated proteins. Selectivity was investigated by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. The detection limit for phosphopeptide enrichment by the MagSiO2@SiO2@PDA@Ti(IV) microspheres from the tryptic digests of β-casein was 50 fmol/mL. Usability of the proposed magnetic sorbent with complex biological samples was demonstrated by successful enrichment of four phosphopeptides from human serum. The proposed sorbent showed stable performance over five repeated uses.
authors.affiliation: Chemical Engineering Department, Hacettepe University, 06800, Ankara, Turkey.
authors.forename: Kouroush
authors.initials: K
authors.lastname: Salimi
authors.affiliation: Department of Medical Biology and Genetics, Faculty of Medicine, Gazi University, 06500, Ankara, Turkey; Department of Medical Biology, Faculty of Medicine, İstanbul Medeniyet University, 34700, Istanbul, Turkey.
authors.forename: Duygu Deniz
authors.initials: DD
authors.lastname: Usta
authors.affiliation: Department of Chemistry, Hacettepe University, 06800, Ankara, Turkey; Institute of Science, Division of Bioengineering, Hacettepe University, 06800, Ankara, Turkey.
authors.forename: Ömür
authors.initials: Ö
authors.lastname: Çelikbıçak
authors.affiliation: Department of Medical Biochemistry, Faculty of Medicine, Hacettepe University, 06100, Ankara, Turkey.
authors.forename: Asli
authors.initials: A
authors.lastname: Pinar
authors.affiliation: Department of Chemistry, Hacettepe University, 06800, Ankara, Turkey.
authors.forename: Bekir
authors.initials: B
authors.lastname: Salih
authors.affiliation: Chemical Engineering Department, Hacettepe University, 06800, Ankara, Turkey; Division of Nanotechnology and Nanomedicine, Hacettepe University, 06800, Ankara, Turkey. Electronic address: atuncel@hacettepe.edu.tr.
authors.forename: Ali
authors.initials: A
authors.lastname: Tuncel
mesh_terms: D020099:Coated Materials, Biocompatible / Q000737:chemistry*; D006801:Humans; D007211:Indoles / Q000737:chemistry*; D060328:Magnetic Phenomena; D008863:Microspheres; D015394:Molecular Structure; D010316:Particle Size; D010748:Phosphopeptides / Q000032:analysis*; D011108:Polymers / Q000737:chemistry*; D016062:Porosity; D012822:Silicon Dioxide / Q000737:chemistry*; D013499:Surface Properties; D014025:Titanium / Q000737:chemistry*
chemical_list: D020099:Coated Materials, Biocompatible; D007211:Indoles; D010748:Phosphopeptides; D011108:Polymers; C568283:polydopamine; D012822:Silicon Dioxide; D014025:Titanium
keywords: Adsorption; Core–shell nanoparticle; Magnetic silica nanoparticle; Phosphopeptide enrichment