title: Label-Free Carbon-Dots-Based Ratiometric Fluorescence pH Nanoprobes for Intracellular pH Sensing.
abstract: Measuring pH in living cells is of great importance for better understanding cellular functions as well as providing pivotal assistance for early diagnosis of diseases. In this work, we report the first use of a novel kind of label-free carbon dots for intracellular ratiometric fluorescence pH sensing. By simple one-pot hydrothermal treatment of citric acid and basic fuchsin, the carbon dots showing dual emission bands at 475 and 545 nm under single-wavelength excitation were synthesized. It is demonstrated that the fluorescence intensities of the as-synthesized carbon dots at the two emissions are pH-sensitive simultaneously. The intensity ratio (I475 nm/I545 nm) is linear against pH values from 5.2 to 8.8 in buffer solution, affording the capability as ratiometric probes for intracellular pH sensing. It also displays that the carbon dots show excellent reversibility and photostability in pH measurements. With this nanoprobe, quantitative fluorescence imaging using the ratio of two emissions (I475 nm/I545 nm) for the detection of intracellular pH were successfully applied in HeLa cells. In contrast to most of the reported nanomaterials-based ratiometric pH sensors which rely on the attachment of additional dyes, these carbon-dots-based ratiometric probes are low in toxicity, easy to synthesize, and free from labels.
authors.affiliation: State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Biology, College of Chemistry and Chemical Engineering, Hunan University , Key Laboratory for Bio-Nanotechnology and Molecule Engineering of Hunan Province, Changsha 410082, China.
authors.forename: Jingfang
authors.initials: J
authors.lastname: Shangguan
authors.affiliation: State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Biology, College of Chemistry and Chemical Engineering, Hunan University , Key Laboratory for Bio-Nanotechnology and Molecule Engineering of Hunan Province, Changsha 410082, China.
authors.forename: Dinggeng
authors.initials: D
authors.lastname: He
authors.affiliation: State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Biology, College of Chemistry and Chemical Engineering, Hunan University , Key Laboratory for Bio-Nanotechnology and Molecule Engineering of Hunan Province, Changsha 410082, China.
authors.forename: Xiaoxiao
authors.initials: X
authors.lastname: He
authors.affiliation: State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Biology, College of Chemistry and Chemical Engineering, Hunan University , Key Laboratory for Bio-Nanotechnology and Molecule Engineering of Hunan Province, Changsha 410082, China.
authors.forename: Kemin
authors.initials: K
authors.lastname: Wang
authors.affiliation: State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Biology, College of Chemistry and Chemical Engineering, Hunan University , Key Laboratory for Bio-Nanotechnology and Molecule Engineering of Hunan Province, Changsha 410082, China.
authors.forename: Fengzhou
authors.initials: F
authors.lastname: Xu
authors.affiliation: State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Biology, College of Chemistry and Chemical Engineering, Hunan University , Key Laboratory for Bio-Nanotechnology and Molecule Engineering of Hunan Province, Changsha 410082, China.
authors.forename: Jinquan
authors.initials: J
authors.lastname: Liu
authors.affiliation: State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Biology, College of Chemistry and Chemical Engineering, Hunan University , Key Laboratory for Bio-Nanotechnology and Molecule Engineering of Hunan Province, Changsha 410082, China.
authors.forename: Jinlu
authors.initials: J
authors.lastname: Tang
authors.affiliation: State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Biology, College of Chemistry and Chemical Engineering, Hunan University , Key Laboratory for Bio-Nanotechnology and Molecule Engineering of Hunan Province, Changsha 410082, China.
authors.forename: Xue
authors.initials: X
authors.lastname: Yang
authors.affiliation: State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Biology, College of Chemistry and Chemical Engineering, Hunan University , Key Laboratory for Bio-Nanotechnology and Molecule Engineering of Hunan Province, Changsha 410082, China.
authors.forename: Jin
authors.initials: J
authors.lastname: Huang
mesh_terms: D002244:Carbon / Q000737:chemistry; D002470:Cell Survival / Q000187:drug effects; D002738:Chloroquine / Q000737:chemistry / Q000494:pharmacology; D003593:Cytoplasm / Q000737:chemistry*; D003907:Dexamethasone / Q000737:chemistry / Q000494:pharmacology; D006367:HeLa Cells; D006801:Humans; D006863:Hydrogen-Ion Concentration; D018625:Microscopy, Atomic Force; D018613:Microscopy, Confocal; D045663:Quantum Dots / Q000737:chemistry* / Q000633:toxicity; D017382:Reactive Oxygen Species / Q000032:analysis; D013438:Sulfhydryl Compounds / Q000032:analysis
chemical_list: D017382:Reactive Oxygen Species; D013438:Sulfhydryl Compounds; D002244:Carbon; D003907:Dexamethasone; D002738:Chloroquine