Development of ultrabright semiconducting polymer dots for ratiometric pH sensing

Yang-Hsiang Chan, Changfeng Wu, Fangmao Ye, Yuhui Jin, Polina B. Smith, Daniel T. Chiu

Research output: Contribution to journalArticle

196 Scopus citations


Semiconducting polymer-based nanoparticles (Pdots) have recently emerged as a new class of ultrabright probes for biological detection and imaging. This paper describes the development of poly(2,5-di(3′,7′-dimethyloctyl) phenylene-1,4-ethynylene) (PPE) Pdots as a platform for designing Förster resonance energy transfer (FRET)-based ratiometric pH nanoprobes. We describe and compare three routes for coupling the pH-sensitive dye, fluorescein, to PPE Pdots, which is a pH-insensitive semiconducting polymer. This approach offers a rapid and robust sensor for pH determination using the ratiometric methodology where excitation at a single wavelength results in two emission peaks, one that is pH sensitive and the other one that is pH insensitive for use as an internal reference. The linear range for pH sensing of the fluorescein-coupled Pdots is between pH 5.0 and 8.0, which is suitable for most cellular studies. The pH-sensitive Pdots show excellent reversibility and stability in pH measurements. In this paper, we use them to measure the intracellular pH in HeLa cells following their uptake by endocytosis, thus demonstrating their utility for use in cellular and imaging experiments.

Original languageEnglish
Pages (from-to)1448-1455
Number of pages8
JournalAnalytical Chemistry
Issue number4
StatePublished - 15 Feb 2011

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