Salimi Kouroush, Usta Duygu Deniz, Çelikbıçak Ömür, Pinar Asli, Salih Bekir, Tuncel Ali
Chemical Engineering Department, Hacettepe University, 06800, Ankara, Turkey.
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.
Colloids Surf B Biointerfaces. 2017 May 1;153:280-290. doi: 10.1016/j.colsurfb.2017.02.028. Epub 2017 Feb 22.
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 Ti 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 (MagSiO) 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 Ti attachment (MagSiO@SiO). The MagSiO@SiO microspheres were coated with a polydopamine shell (MagSiO@SiO@PDA) and Ti was attached onto the composite microspheres (MagSiO@SiO@PDA@Ti(IV)). Formation of the PDA layer and Ti 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 MagSiO@SiO@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.
磁性核壳纳米颗粒的一个重要缺点是，围绕磁芯形成功能壳会导致饱和磁化强度显著降低。Ti(IV)功能化固定化金属亲和色谱（IMAC）吸附剂的另一个缺点是，用于将Ti附着到复合磁性纳米颗粒上的结合介质具有酸性，由于酸性部分与磁芯之间的化学相互作用，这会导致饱和磁化强度进一步降低。为了富集磷酸肽，设计了一种相对于磁性核壳纳米颗粒具有优异且稳定磁性的磁性微球形式的IMAC吸附剂。通过一种新的分段形状模板水解缩合方案合成了尺寸为6μm的磁性单分散多孔二氧化硅微球（MagSiO）。在微球周围生成多孔二氧化硅壳层，以在Ti附着过程中保护磁芯免受酸性介质的影响（MagSiO@SiO）。MagSiO@SiO微球涂覆有多巴胺壳（MagSiO@SiO@PDA），并将Ti附着到复合微球上（MagSiO@SiO@PDA@Ti(IV)）。PDA层的形成和Ti的附着并未导致饱和磁化强度有任何显著降低。该平台在从磷酸化蛋白质消化物中富集磷酸肽方面表现出优异的性能。通过基质辅助激光解吸/电离飞行时间质谱法研究了选择性。MagSiO@SiO@PDA@Ti(IV)微球从β-酪蛋白胰蛋白酶消化物中富集磷酸肽的检测限为50 fmol/mL。通过成功从人血清中富集四种磷酸肽，证明了所提出的磁性吸附剂在复杂生物样品中的可用性。所提出的吸附剂在五次重复使用中表现出稳定的性能。
