Fluorescence "On-off-on" Strategy For The Detection Of Small Molecular Drugs Based On The Biocompatible Silver Nanoclusters

Silver nanoclusters?Ag NCs?composed of several to hundreds of silver atoms are particularly attractive as novel luminescent nanoprobes due to their subnanometer size,high luminescent quantum yield,good biocompatibility,and easy to preparation.In recent years,many fluorescence methods have been widely applied in the detection of biomacromolecules and heavy metal ions based on the Ag NCs probe.Compared with traditional organic fluorescenc dyes,Ag NCs are stable optical probes,which can avoid the photobleaching.Besides,these label-free fluorescence methods also can avoid the tedious operation process and the use of expensive instruments.Additionally,the background signal can be effectively reduced with introduction of fluorescence quencher,and thus a highly sensitive detection of targets.Therefore,we make full use of the advantages of Ag NCs to developed simple,rapid and high sensitive “on-off-on” fluorescence methods based on biocompatible materials stabilized Ag NCs,and to achieve the application in the detection of small molecular drugs in human body fluids and pharmaceutical formulations.The researches include the following two parts:Part ? Copper???-mediated silver nanoclusters as a fluorescent probe for the detection of alendronate sodiumIn this work,a new fluorescence method for the detection of ALDS based on the Cu²⁺ mediated Ag NCs as a fluorescent probe have been achieved.ALDS is an important and regularly used medicine in clinical therapy of osteoporosis.Quantitative detection of ALDS in human body fluid and quality control of ALDS in related medicines are of great importance.Herein,Ag NCs with strong red photoluminescence are prepared by employing DNA as the template?on?.Specifically,Cu²⁺ can selectively bind with DNA-stabilized Ag NCs and thus greatly quench their red fluorescence?off?.In the presence of ALDS,their fluorescence can largely recover again owing to the stronger coordination of ALDS with Cu²⁺?on?.On the basis of such a mechanism,fluorescence “on-off-on” mode of the nanoprobe is applied to detect ALDS in a wide linear range of 800 pmol/L²00 ?mol/L,with a detection limit of 100 pmol/L.Compared with previously reported methods,the present approach has significant advantages regard to simplicity,high sensitivity,and a wide detectable concentration range.This method has been successfully applied in ALDS assay in tablets and human urine and serum samples.Part ? Silver nanoclusters-MnO₂ nanosheets as a fluorescent probe for the detection of isoniazidIn this work,a rapid and simple fluorescence “on-off-on” assay is developed for INH determination using a fluorescent probe of Ag NCs-MnO₂ nanosheets.INH is an effective and indispensable basic tuberculostatic drug and widely used for prevention and treatment of tuberculosis.The therapeutic effect and the health of patients are closely associated with the dosage of medication.Quantitative detection of INH in human body fluid and quality control of INH in related medicines are of great importance to achieve an efficient treatment of tuberculosis.In the proposed sensing system,the strong red fluorescence of PMAA-Ag NCs can be greatly quenched by MnO₂ nanosheets through FRET?off?.Upon the introduction of INH,MnO₂ nanosheets can be reduced to Mn2+,and thus their fluorescence can recover again?on?.On the basis of the “on-off-on” fluorescence method,we can highly sensitive detection of INH in the range of 0.8 ?mol/L²00 ?mol/L,with a limit of detection of 476 nmol/L.The present strategy shows remarkable advantages including simplicity,rapidness,high sensitivity,low-cost and environmental-friendly.This method is also practical,which has been applied in the detection of INH in human body fluids and pharmaceutical formulations.