Wavelength encoded analytical imaging and fiber optic sensing with pH sensitive CdTe quantum dots

• Type: Article in International Scientific Journal
• Date: 2010

Authors

maule, c (Author) Other; goncalves, h (Author) Other; mendonca, c (Author) Other; sampaio, p (Author) Other; da silva, jcge (Author) FCUP; jorge, p (Author) FCUP

Journal

Title: Talanta

Vol. 80 No. 5

Pages: 1932-1938

ISSN: 0039-9140

Publisher: Elsevier

Indexing

ISI Web of Knowledge - 36 Citations

ISI Web of Science

Scopus - 38 Citations

Scientific classification

FOS: Natural sciences > Chemical sciences

Other information

Authenticus ID: P-003-8AJ

DOI: 10.1016/j.talanta.2009.10.048

Abstract (EN): CdTe quantum dots (QDs), capped with mercaptopropionic acid (MPA), were synthesized and the variation of their fluorescence properties (steady state and lifetime)with pH was assessed in solution and when immobilized in a sol-gel host Three different sizes of CdTe QDs with excited state lifetimes ranging from 42 to 48 ns and with emission maximum at 540 nm (QD(540)). 580 nm (QD(580)) and 625 nm (QD(625)) were selected The solution pH affects the maximum emission wavelength (shifts to higher wavelengths of 23, 24 and 27 nm for QD(540), QD(550) and QP(625), respectively), the excited state lifetime and the fluorescence intensity in a reversible way. Linearization of the maximum emission wavelength variation with the pH allows the estimation of an apparent ionization constant (pK(a)) for each QD: 6.5 +/- 0.1 (QD(540)), 6.1 +/- 0.5 (QD(580)) and 5.4 +/- 0.3 (QD(625)) The variation of the QDs fluorescence properties was further explored using confocal laser scanning microscopy allowing the implementation of a new calibration method for pH imaging in solution QDs were successfully immobilized on the tip of an optical fiber by dip-coating using sal-gel procedure The immobilized QDs showed a similar pH behaviour to the one observed in solution and an apparent lifetime of 80,68 and 99 ns, respectively. The proposed QDs based methodology can be successfully used to monitor pH using wavelength encoded data in imaging and fiber optic sensing applications.

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 7