title: Highly sensitive detection of copper ions by densely grafting fluorescein inside polyethyleneimine core-silica shell nanoparticles.
abstract: In this work, polyethyleneimine (PEI) core-silica shell nanoparticles were synthesized and used for densely grafting fluorescent receptor units inside the core of these particles to result in multi-receptor units collectively sensing a target. Herein, copper ion quenching of the fluorescence intensity of a fluorescein isothiocyanate (FITC) system was selected as a model to confirm our proof-of-concept strategy. Our results showed that, compared to free FITC in solution, a 10-fold enhancement of the Stern-Volmer constant value for Cu(2+) quenching of the fluorescence intensity of the grafted state of FITC in PEI core-silica shell nanoparticles was achieved. Furthermore, compared to a previous collective sensing scheme by densely grafting fluorescent receptor units on a silica nanoparticle surface, the proposed scheme, which grafted fluorescent receptor units inside a polymer nano-core, was simple, highly efficient and presented higher sensitivity.
authors.affiliation: Key Laboratory of Analytical Chemistry for Life Science of Shaanxi Province, School of Chemistry & Chemical Engineering, Shaanxi Normal University, Xi'an 710062, P. R. China. zhengxw@snnu.edu.cn.
authors.forename: Yali
authors.initials: Y
authors.lastname: Qiao
authors.affiliation: Key Laboratory of Analytical Chemistry for Life Science of Shaanxi Province, School of Chemistry & Chemical Engineering, Shaanxi Normal University, Xi'an 710062, P. R. China. zhengxw@snnu.edu.cn.
authors.forename: Xingwang
authors.initials: X
authors.lastname: Zheng
mesh_terms: D002623:Chemistry Techniques, Analytical / Q000379:methods*; D003300:Copper / Q000032:analysis* / Q000737:chemistry; D019793:Fluorescein / Q000737:chemistry*; D007477:Ions / Q000032:analysis; D057230:Limit of Detection; D046529:Microscopy, Electron, Transmission; D053758:Nanoparticles / Q000737:chemistry*; D011094:Polyethyleneimine / Q000737:chemistry*; D016062:Porosity; D012822:Silicon Dioxide / Q000737:chemistry*; D013050:Spectrometry, Fluorescence
chemical_list: D007477:Ions; D012822:Silicon Dioxide; D003300:Copper; D011094:Polyethyleneimine; D019793:Fluorescein