title: Highly sensitive optical biosensor for thrombin based on structure switching aptamer-luminescent silica nanoparticles.
abstract: We describe here the construction of a sensitive and selective optical sensor system for the detection of human α-thrombin. The surface functionalized luminescent [Ru(dpsphen)(3)](4-) (dpsphen-4,7-diphenyl-1,10-phenanthroline disulfonate) ion doped silica nanoparticles (SiNPs) with a size ~70 nm have been prepared. The DABCYL (2-(4-dimethylaminophenyl)diazenyl-benzoic acid) quencher labeled thrombin binding aptamer is conjugated to the surface of SiNPs using BS(3) (bis(sulfosuccinimidyl) suberate) as a cross-linker, resulting in the conformational change of aptamer to form G-quadruplex structure upon the addition of thrombin. The binding event is translated into a change in the luminescence intensity of Ru(II) complex via FRET mechanism, due to the close proximity of DABCYL quencher with SiNPs. The selective detection of thrombin using the SiNPs-aptamer system up to 4 nM is confirmed by comparing its sensitivity towards other proteins. This work demonstrates the application of simple aptamer-SiNPs conjugate as a highly sensitive system for the detection of thrombin and also it is highly sensitive towards thrombin in the presence of other proteins and complex medium such as BSA.
authors.affiliation: School of Chemistry, Madurai Kamaraj University, Madurai 625 021, India.
authors.forename: Ethiraju
authors.initials: E
authors.lastname: Babu
authors.forename: Paulpandian Muthu
authors.initials: PM
authors.lastname: Mareeswaran
authors.forename: Seenivasan
authors.initials: S
authors.lastname: Rajagopal
mesh_terms: D052157:Aptamers, Nucleotide / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D001483:Base Sequence; D015374:Biosensing Techniques / Q000379:methods*; D049408:Luminescent Agents / Q000737:chemistry; D053758:Nanoparticles / Q000737:chemistry*; D055620:Optical Phenomena; D009942:Organometallic Compounds / Q000737:chemistry; D010618:Phenanthrolines / Q000737:chemistry; D012428:Ruthenium / Q000737:chemistry; D012822:Silicon Dioxide / Q000737:chemistry*; D013917:Thrombin / Q000378:metabolism*; D004124:p-Dimethylaminoazobenzene / Q000031:analogs & derivatives / Q000737:chemistry
chemical_list: D052157:Aptamers, Nucleotide; D049408:Luminescent Agents; D009942:Organometallic Compounds; D010618:Phenanthrolines; C063127:4-(4-dimethylaminophenylazo)benzoic acid; D012822:Silicon Dioxide; D012428:Ruthenium; D004124:p-Dimethylaminoazobenzene; D013917:Thrombin