Next Article in Journal
Suitability of the Cyclic Voltammetry Measurements and DPPH• Spectrophotometric Assay to Determine the Antioxidant Capacity of Food-Grade Oenological Tannins
Previous Article in Journal
ANOVA Design for the Optimization of TiO2 Coating on Polyether Sulfone Membranes
Previous Article in Special Issue
Metamaterial Lensing Devices
Article Menu

Export Article

Open AccessArticle

Ratiometric pH Sensing and Imaging in Living Cells with Dual-Emission Semiconductor Polymer Dots

College of Chemistry and Life Sciences, Zhejiang Normal University, Jinhua 321004, China
Xingzhi College, Zhejiang Normal University, Jinhua 321004, China
Authors to whom correspondence should be addressed.
Molecules 2019, 24(16), 2923;
Received: 23 July 2019 / Revised: 6 August 2019 / Accepted: 10 August 2019 / Published: 12 August 2019
(This article belongs to the Special Issue Optical Properties of Nanomaterials)
PDF [3633 KB, uploaded 12 August 2019]


Polymer dots (Pdots) represent newly developed semiconductor polymer nanoparticles and exhibit excellent characteristics as fluorescent probes. To improve the sensitivity and biocompatibility of Pdots ratiometric pH biosensors, we synthesized 3 types of water-soluble Pdots: Pdots-PF, Pdots-PP, and Pdots-PPF by different combinations of fluorescent dyes poly(9,9-dioctylfluorenyl-2,7-diyl) (PFO), poly[(9,9-dioctyl-fluorenyl-2,7-diyl)-co-(1,4-benzo-{2,1′,3}-thiadazole)] (PFBT), and fluorescein isothiocyanate (FITC). We found that Pdots-PPF exhibits optimal performance on pH sensing. PFO and FITC in Pdots-PPF produce pH-insensitive (λ = 439 nm) and pH-sensitive (λ = 517 nm) fluorescence respectively upon a single excitation at 380 nm wavelength, which enables Pdots-PPF ratiometric pH sensing ability. Förster resonance energy transfer (FRET) together with the use of PFBT amplify the FITC signal, which enables Pdots-PPF robust sensitivity to pH. The emission intensity ratio (I517/I439) of Pdots-PPF changes linearly as a function of pH within the range of pH 3.0 to 8.0. Pdots-PPF also possesses desirable reversibility and stability in pH measurement. More importantly, Pdots-PPF was successfully used for cell imaging in Hela cells, exhibiting effective cellular uptake and low cytotoxicity. Our study suggests the promising potential of Pdots-PPF as an in vivo biomarker. View Full-Text
Keywords: Pdots; semiconductor polymer; FRET; pH sensing; cell imaging Pdots; semiconductor polymer; FRET; pH sensing; cell imaging

Figure 1

This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited (CC BY 4.0).

Share & Cite This Article

MDPI and ACS Style

Chen, P.; Ilyas, I.; He, S.; Xing, Y.; Jin, Z.; Huang, C. Ratiometric pH Sensing and Imaging in Living Cells with Dual-Emission Semiconductor Polymer Dots. Molecules 2019, 24, 2923.

Show more citation formats Show less citations formats

Note that from the first issue of 2016, MDPI journals use article numbers instead of page numbers. See further details here.

Related Articles

Article Metrics

Article Access Statistics



[Return to top]
Molecules EISSN 1420-3049 Published by MDPI AG, Basel, Switzerland RSS E-Mail Table of Contents Alert
Back to Top