Ultrasensitive detection of CA125 based on a triple signal amplification strategy with a huge number of loaded probes exonuclease cyclic cleavage, rolling cyclic amplification and strand self-growth.

A novel electrochemiluminescence (ECL) aptamer biosensor with high sensitivity and selectivity for the detection of tumor biomarker carbohydrate antigen 125 (CA125) was constructed, and a strategy of triple amplification of signals was proposed using an exonuclease cyclic cleavage aptamer, combined with rolling ring amplification technologies, generating multi-branched dendritic double-stranded DNA to load a large number of probes through "strand self-growth". The double-stranded DNA, which is abbreviated as CP/CA dsDNA, formed by hybridizing the single strand of capture DNA (CP DNA) with the single strand DNA of the CA125 aptamer (CA Apt) was modified on FeO@Au. When CA125 was added, CP/CA dsDNA was unwound, and CA125 specifically combined with CA Apt to form a protein-aptamer complex, leaving only CP DNA on the surface of FeO@Au.

A sensitive electrochemiluminescence DNA biosensor based on the signal amplification of ExoIII enzyme-assisted hybridization chain reaction combined with nanoparticle-loaded multiple probes.

An electrochemiluminescence (ECL) DNA biosensor based on ExoIII exonuclease assistance and hybridization chain reaction (HCR) amplification technology has been constructed. ExoIII exonuclease and triple-helix DNA molecular switch are used in detecting a target in circulation. By combining HCR with AuNPs@DNA, a novel signal probe is built, which enables multiple signal amplification and the high-sensitive detection of transgenic rice BT63 DNA.

Effect of TiO2 colloids on the fluorescence behavior of two cyanine dyes.

The photophysical properties of two typical cyanine dyes [3,3'-diethyl-9-methyl-thiacarbocyanine iodide (dye A) and anhydro-3,3'-disulfopropyl-5,5'-diphenyl-9-ethyloxacarbocyanine hydroxide (dye B)] in the absence and presence of TiO(2) colloids have been investigated by UV-visible spectroscopy, (1)H-NMR spectroscopy, fluorescence spectroscopy, fluorescence lifetime measurements, and ESR measurements. It was found from the absorption spectra and NMR results that there are two isomers in the ground state of these dyes. Steady-state fluorescence spectra show that the fluorescence intensities of dye A and dye B are enhanced and quenched by TiO(2) colloids, respectively.

Photoinduced electron transfer from the excited J-aggregate state of a thiacarbocyanine dye to TiO2 colloids.

The photophysical properties of the J-aggregate of 3,3'-di(3-sulfopropyl)-4,5,4',5'-dibenzo-9-phenyl-thiacarbocyanine triethyl-ammonium salt in the absence and presence of TiO(2) colloids have been studied using UV-visible absorption spectroscopy, steady-state and time-resolved fluorescence spectroscopy, and ESR spectroscopy. The fluorescence emission of the J-aggregate decreases with increasing concentration of TiO(2) colloids. The average fluorescence lifetime of the J-aggregate in the presence of TiO(2) colloids is shorter than that in the absence of TiO(2) colloids.

Effects of NaCl on the J-aggregation of two thiacarbocyanine dyes in aqueous solutions.

The effects of NaCl on the aggregation of two typical thiacarbocyanine dyes (3,3'-di(3-sulfopropyl)-4,5,4',5'-dibenzo-9-phenyl-thiacarbocyanine triethyl ammonium salt (Dye 1) and 3,3'-di(3-sulfopropyl)-4,5,4',5'-dibenzo-9-methyl-thiacarbocyanine triethyl ammonium salt (Dye 2)) in aqueous solution have been studied by using absorption spectroscopy, fluorescence spectroscopy, and 1H- and 23Na-NMR measurements. It is found that the J-aggregation of two dyes can be promoted by the addition of NaCl and that the effective coherence length of the J-aggregate is shorter than that obtained without NaCl. Fluorescence spectra demonstrate that the fluorescence intensities of the J-aggregates of two dyes are quenched by addition of NaCl.

Effect of beta-Cyclodextrin on the Photoinduced Charge Transfer in Sodium 1-Anilino-8-naphthalene Sulfate (ANS)/CdS Colloidal System.

The S-center radical (ANS(.)) of sodium 1-anilino-8-naphthalene sulfate (ANS) generated by photoinduced charge transfer in ANS/CdS and ANS/CdS/beta-cyclodextrin(beta-CD) systems has been studied by using spin trapping electron spin resonance techniques, UV-visible spectroscopic methods, and fluorescence spectroscopic methods. It was found that the S-centered radical (ANS(.