Enrichment of Peptides using Novel C8-functionalized Magnetic Nanoparticles for Matrix-Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometric Analysis

Sun-Mi Song,Hyo-Jik Yang,Seong-Jae Shin,Eun-Hye Park,Jeong-Kwon Kim,Jin-Hee Kim

doi:10.5478/msl.2011.2.2.053

Abstract

C8-functionalized magnetic nanoparticles were synthesized by coating magnetic Fe3O4 nanoparticles with silica–amine groups using 3-aminopropyltriethoxysilane and by subsequently modifying the amine groups with chloro(dimethyl)octylsilaneto produce octyl groups on the surface of the MNPs. The C8-functionalized MNPs were used to enrich peptides from trypticprotein digests of myoglobin and α-casein. The enriched peptides were analyzed by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI−ΤΟF−MS). MALDI-MS was also used to investigate desalting of the C8-functionalized MNPs. Sample solutions were prepared in 1.0 M NaCl, and the successful removal of salt was observed. Enrichmentwith C8-functionalized MNPs was very effective for separating and concentrating tryptic peptides.

Highlights

Magnetic materials have been used for separating and enriching proteins or peptides.[1,2,3,4,5] Magnetite (Fe O ) 34 nanoparticles are popular due to their superparamagnetic properties, which endow the nanoparticles with strong magnetic responsibility, reducing sample preparation time.[4,5] The surface of magnetic nanoparticles (MNPs) is commonly modified with specific functional groups for various applications.[6]MNPs coated with alkyl groups can be used to enrich peptides through hydrophobic interactions between alkyl groups and peptides
Myoglobin derived from horse heart, α-casein from bovine milk, bradykinin, angiotensin I, adenocorticotropic hormone, 3-aminopropyltriethoxysilane, 2,5-dihydroxybenzoic acid (DHB), ammonium bicarbonate, sodium chloride (NaCl), chlorooctylsilane, iron(II) chloride hexahydrate, iron(III) chloride tetrahydrate, pyridine, phosphoric acid, and trifluoroacetic acid (TFA) were purchased from Sigma-Aldrich
The synthesis of C8-MNPs consists of three steps: synthesis of MNPs, modification of MNPs with active functional groups, and attachment of octyl groups

Summary

Introduction

Magnetic materials have been used for separating and enriching proteins or peptides.[1,2,3,4,5] Magnetite (Fe O ) 34 nanoparticles are popular due to their superparamagnetic properties, which endow the nanoparticles with strong magnetic responsibility, reducing sample preparation time.[4,5] The surface of magnetic nanoparticles (MNPs) is commonly modified with specific functional groups for various applications.[6]. Laboratory-prepared C -MNPs were used to enrich peptides from serum using FeCl ·6H O and 1,6-hexadiamine to coat the Fe O surface with amine functional groups to prepare amine-functionalized MNPs, which were modified with chloro(dimethyl)octylsilane.[5] MNPs synthesized with. 17 33 were used to extract peptides and proteins from aqueous solutions.[7] Alternatively, MNPs were enclosed in a silica shell after reacting with tetraethylorthosilicate and subsequently modified with chloro(dimethyl)octylsilane[4] to generate C 8. C - and C -functionalized MNPs.[8] In the present study, C - MNPs were synthesized using a method in which the surface of the MNPs was modified by 3-aminopropyltriethoxysilane (APES)[9,10] to generate an amino silane coating and by

Materials and Methods

Results and Discussion

Conclusions