title: Aptasensor based on triplex switch for SERS detection of cytochrome c.
abstract: We report a sensitive approach for SERS detection of cytochrome c using target binding-induced conformational changes of signal transduction probe (STP). STP labeled with a SERS-active molecule, carboxy-X-rhodamine (ROX), is immobilized on the substrate where the formation of a rigid triplex switching structure with aptamers does not allow SERS amplification to take place. The target binding event leads to an enhancement in SERS intensity of ROX adsorbed on the gold surface. Meanwhile, we found that an appropriate STP surface density could shield the SERS signal produced by protein adsorption which would foul the sensing surface. In addition, cytochrome c aptamers used were not the original sequence but reorganized in the nonspecific binding site to adapt to our design. This method provides a low detection limit of 2 nM (10 fmol within 5 μL sample solution), and shows good selectivity toward cytochrome c compared to interfering proteins such as hemoglobin and immunoglobulin G. The general strategy of the method can also be extended to aptamer or DNA based sensors.
authors.affiliation: Life and Environmental Science College, Shanghai Normal University, Shanghai, 200234, P R China.
authors.forename: Yunfeng
authors.initials: Y
authors.lastname: Xia
authors.forename: Peiyi
authors.initials: P
authors.lastname: Gao
authors.forename: Xiaowen
authors.initials: X
authors.lastname: Qiu
authors.forename: Qinghao
authors.initials: Q
authors.lastname: Xu
authors.forename: Siwen
authors.initials: S
authors.lastname: Gan
authors.forename: Haifeng
authors.initials: H
authors.lastname: Yang
authors.forename: Shasheng
authors.initials: S
authors.lastname: Huang
mesh_terms: D052157:Aptamers, Nucleotide / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D001483:Base Sequence; D015374:Biosensing Techniques / Q000379:methods*; D045304:Cytochromes c / Q000032:analysis* / Q000737:chemistry / Q000378:metabolism; D004247:DNA / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D008958:Models, Molecular; D011487:Protein Conformation; D013059:Spectrum Analysis, Raman; D013499:Surface Properties
chemical_list: D052157:Aptamers, Nucleotide; C051802:triplex DNA; D045304:Cytochromes c; D004247:DNA