Chemo/biosensing Based On Novel Fluorescence Probes Of Gold,Silver Nanocomposites

Noble metal materials,especially gold?Au?and silver?Ag?nanomaterials have attracted worldwide attention in both fundamental research and industrial application on account of their unique physical and chemical properties and tunable optical performances.The preparation and application of gold and silver nano-structure materials and their complexs have become one of the hot research topics in modern analytical science.In this paper,new composite systems based on pyrene derivatives,conjugated polyelectrolytes and nobel metal nanocomposites were constructed for the fluorescent sensing of etimicin,pyrophosphate ion and iron???ion with high sensitivity.The main contents of the dissertation are summarized in the following:?1?A new ratiometric nanosystem is developed for selective and ultrasensitivedetectionofetimicinbasedon N,N-bis-?1-pyrenecarboxaldehyde?-1,12-dodecanediamine?probe 1?and citrate-stabilized silver nanoparticles?AgNPs?.Probe 1,a bispyrene schiff base derivative,is designed to function as a sensitive ratiometric fluorescence probe owing to the spatial sensitivity of characteristic peak of monomer and excimer.Meanwhile,AgNPs can serve as an excellent fluorescent quencher of probe 1 as well as a colorimetric probe.In the presence of etimicin,the fluorescence intensity at 396 nm?monomer?increases owing to the fluorescence recovery of probe 1.Moreovere,etimicin can induce the aggregation of AgNPs and subsequently enhance the emission quenching of probe 1/AgNPs at 483 nm?excimer?due to the restriction of conformational change of bispyrene molecule,thus leading to the corresponding ratiometric fluorescent measurement of analyte.Additionally,analyte-caused aggregation of AgNPs also favors ratiometric colorimetric detection of etimicin.Under the optimum conditions,this ratiometric nanosensor can be applied to the fluorescent and colorimetric analysis of etimicin with the detection limit as low as0.05 nM and 0.25 nM?S/N=3?,respectively.?2?A novel nanosensor is developed for ultrasensitive detection of pyrophosphate ion?PPi?based on conjugated polyelectrolyte-stabilized silver nanoparticles?P2-AgNPs?.The strong fluorescence of P2-AgNPs was quenched upon the addition of copper???-amino acid complexes and could then be restored in the presence of PPi.Based on these phenomena,the use of the P2-AgNPs-Cu²⁺composite system as a selective fluorescent probe for PPi detection was constructed.The lowest detectable concentration of PPi was 50 nM herein.?3?A fluorescent sensor based on the fluorescence quenching of gold nanorods?GNRs?and conjugated polyelectrolyte?P2?was demonstrated for iron ion(Fe³⁺).This detection scheme relies on the ability of Fe³⁺ion to catalyze the etching of gold in the presence of thiourea species and the binding capacity of the fluorescence of P2/GNRs nanocomposite system was quenched with Fe³⁺.As a result,P2/GNRS nanocomposite exhibited high sensitivity and selectivity for fluorescence detection of Fe³⁺over other metal ions.Under the optimum conditions,the lowest detectable concentration of Fe³⁺was 50 nM.