title: Efficient on-chip proteolysis system based on functionalized magnetic silica microspheres.
abstract: An easily replaceable enzymatic microreactor has been fabricated based on the glass microchip with trypsin-immobilized magnetic silica microspheres (MS microspheres). Magnetic microspheres with small size (approximately 300 nm in diameter) and high magnetic responsivity to magnetic field (68.2 emu/g) were synthesized and modified with tetraethyl orthosilicate (TEOS). Aminopropyltriethoxysilane (APTES) and glutaraldehyde (GA) were then introduced to functionalize the MS microspheres for enzyme immobilization. Trypsin was stably immobilized onto the MS microspheres through the reaction of primary amines of the proteins with aldehyde groups on the MS microspheres. The trypsin-immobilized MS microspheres were then locally packed into the microchannel by the application of a strong field magnet to form an on-chip enzymatic microreactor. The digestion efficiency and reproducibility of the microreactor were demonstrated by using cytochrome c (Cyt-C) as a model protein. When compared with an incubation time of 12 h by free trypsin in the conventional digestion approach, proteins can be digested by the on-chip microreactor in several minutes. This microreactor was also successfully applied to the analysis of an RPLC fraction of the rat liver extract. This opens a route for its further application in top-down proteomic analysis.
authors.affiliation: Department of Chemistry, Institute of Biomedical Science, Fudan University, Shanghai, China.
authors.forename: Yan
authors.initials: Y
authors.lastname: Li
authors.forename: Bo
authors.initials: B
authors.lastname: Yan
authors.forename: Chunhui
authors.initials: C
authors.lastname: Deng
authors.forename: Wenjia
authors.initials: W
authors.lastname: Yu
authors.forename: Xiuqing
authors.initials: X
authors.lastname: Xu
authors.forename: Pengyuan
authors.initials: P
authors.lastname: Yang
authors.forename: Xiangmin
authors.initials: X
authors.lastname: Zhang
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D045304:Cytochromes c / Q000737:chemistry / Q000378:metabolism; D004800:Enzymes, Immobilized / Q000737:chemistry / Q000378:metabolism*; D056656:Lab-On-A-Chip Devices; D008110:Liver Extracts / Q000737:chemistry / Q000378:metabolism; D008280:Magnetics; D046208:Microchip Analytical Procedures / Q000379:methods*; D008863:Microspheres; D008969:Molecular Sequence Data; D051381:Rats; D015203:Reproducibility of Results; D012822:Silicon Dioxide / Q000737:chemistry*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D053719:Tandem Mass Spectrometry; D014357:Trypsin / Q000737:chemistry / Q000378:metabolism*
chemical_list: D004800:Enzymes, Immobilized; D008110:Liver Extracts; D012822:Silicon Dioxide; D045304:Cytochromes c; D014357:Trypsin