title: Indication of intracellular physiological pH changes by L-cysteine-coated CdTe quantum dots with an acute alteration in emission color.
abstract: A novel quantum dots (QDs) based biosensor was developed to monitor physiological pH changes in both fixed and living cells by means of pH-dependent emission color of the QDs. In our system, the nominally single-sized colloidal solution samples of the L-cysteine-capped CdTe QDs with intrinsically broadened size distributions were prepared by employing aqueous synthesis technique. The quench of fluorescence intensities of the QDs with a 16 nm red shift of the emission maximum and a color change from green to yellow was observed with a slight pH decrease (from 7.0 to 6.8) in the system. This pH-dependent emission could be attributed to the efficient exciton energy transfer from smaller QDs to larger ones, which was controlled by electrostatic-tuned aggregation/disaggregation (low/high pH values) processes of the QDs. In addition to high stability, the emission shift of the QDs was reversible for at least one cycle under optimal conditions. Our pH biosensor may find potential application for monitoring the intracellular pH changes in both physiological and pathological conditions.
authors.affiliation: Anhui Key Laboratory of Chemo-Biosensing, College of Chemistry and Materials Science, Anhui Normal University, Wuhu, 241000, PR China.
authors.forename: Meifang
authors.initials: M
authors.lastname: Gui
authors.forename: Linjun
authors.initials: L
authors.lastname: Bao
authors.forename: Yunsheng
authors.initials: Y
authors.lastname: Xia
authors.forename: Chao
authors.initials: C
authors.lastname: Wei
authors.forename: Shengzhou
authors.initials: S
authors.lastname: Zhang
authors.forename: Changqing
authors.initials: C
authors.lastname: Zhu
mesh_terms: D015374:Biosensing Techniques / Q000295:instrumentation*; D019187:Cadmium Compounds / Q000737:chemistry*; D020099:Coated Materials, Biocompatible / Q000737:chemistry; D003124:Colorimetry / Q000295:instrumentation*; D003545:Cysteine / Q000737:chemistry*; D004867:Equipment Design; D019544:Equipment Failure Analysis; D006863:Hydrogen-Ion Concentration; D007424:Intracellular Fluid / Q000737:chemistry*; D045663:Quantum Dots; D013691:Tellurium / Q000737:chemistry*
chemical_list: D019187:Cadmium Compounds; D020099:Coated Materials, Biocompatible; D003545:Cysteine; D013691:Tellurium; C028337:cadmium telluride