title: Ratiometric pH-dot ANSors.
abstract: A silica based analytical nanosphere sensor (ANSor) containing quantum dots (QDs) is reported, which can measure local pH in a ratiometric fashion. A silane modified reference QD was incorporated into a silica matrix by the Stöber method hydrolysis and polycondensation of tetraethoxysilane, giving highly fluorescent QD-embedded silica particles with high yield. A further QD was then bonded onto the silica particle surface and modified with Nile Blue to render it pH responsive. These two populations of QDs were excited simultaneously and gave out well-separated emission peaks which could be taken as a ratio to yield a ratiometric estimate of pH. The sensors are stable, robust and capable of measuring pH in the physiologically relevant range.
authors.affiliation: Institute of Biotechnology, Department of Chemical Engineering and Biotechnology, University of Cambridge, Tennis Court Road, Cambridge, CB2 1QT, UK.
authors.forename: Xiaojuan
authors.initials: X
authors.lastname: Wang
authors.forename: Chiara
authors.initials: C
authors.lastname: Boschetti
authors.forename: Maria Jose
authors.initials: MJ
authors.lastname: Ruedas-Rama
authors.forename: Alan
authors.initials: A
authors.lastname: Tunnacliffe
authors.forename: Elizabeth A H
authors.initials: EA
authors.lastname: Hall
mesh_terms: D031541:Fluorescence Resonance Energy Transfer; D006863:Hydrogen-Ion Concentration; D045663:Quantum Dots; D012821:Silanes / Q000737:chemistry; D013050:Spectrometry, Fluorescence
chemical_list: D012821:Silanes; C040733:tetraethoxysilane