title: Amplified terminal protection assay of small molecule/protein interactions via a highly characteristic solid-state Ag/AgCl process.
abstract: In this work, we describe a new sensitive strategy for electrochemical detection of protein via small molecule/protein interactions. This assay is based on a terminal protection mechanism that small molecule-linked single-stranded DNA (ssDNA) is protected against hydrolysis by exonuclease I when the target protein is captured by the corresponding small molecule recognition element. Positively charged gold nanoparticles (AuNPs) are attached to the termini-protected and negatively charged ssDNA through electrostatic interactions. Subsequent AuNP-catalyzed silver enhancement followed by a highly characteristic and sensitive solid-state Ag/AgCl process is introduced to the sensing platform to amplify the signal output. By combining the amplification ability resulting from the silver deposition on the surface-captured AuNPs with the inherent high sensitivity of the electrochemical solid-state Ag/AgCl process, our method expands its range to the detection of macromolecules that bind to specific small molecules and enables low picomolar detection of protein. As a model of biotin/streptavidin interaction, a detection limit of 10 pM for streptavidin is readily achieved with desirable sensitivity and specificity, which indicates that the terminal protection assay coupled with the electrochemical solid-state Ag/AgCl process can offer a promising platform for the determination of various of types of proteins or small molecule-protein interactions.
authors.affiliation: Key Laboratory on Luminescence and Real-Time Analysis, Ministry of Education, School of Chemistry and Chemical Engineering, Southwest University, Chongqing 400715, PR China.
authors.forename: Qiong
authors.initials: Q
authors.lastname: Wang
authors.forename: Bingying
authors.initials: B
authors.lastname: Jiang
authors.forename: Jin
authors.initials: J
authors.lastname: Xu
authors.forename: Jiaqing
authors.initials: J
authors.lastname: Xie
authors.forename: Yun
authors.initials: Y
authors.lastname: Xiang
authors.forename: Ruo
authors.initials: R
authors.lastname: Yuan
authors.forename: Yaqin
authors.initials: Y
authors.lastname: Chai
mesh_terms: D000669:Amplifiers, Electronic; D015374:Biosensing Techniques / Q000295:instrumentation; D003217:Conductometry / Q000295:instrumentation*; D004247:DNA / Q000737:chemistry* / Q000235:genetics; D004566:Electrodes; D004867:Equipment Design; D019544:Equipment Failure Analysis; D006046:Gold / Q000737:chemistry; D053768:Metal Nanoparticles / Q000737:chemistry / Q000648:ultrastructure; D040081:Protein Array Analysis / Q000295:instrumentation*; D025941:Protein Interaction Mapping / Q000295:instrumentation*; D011506:Proteins / Q000032:analysis* / Q000235:genetics; D018030:Silver Compounds / Q000737:chemistry*
chemical_list: D011506:Proteins; D018030:Silver Compounds; D006046:Gold; D004247:DNA; C037548:silver chloride