title: In situ probing of intracellular pH by fluorescence from inorganic nanoparticles.
abstract: Intracellular pH (pHi) plays a critical role in the physiological processes of cells. Nanoscale sensors based on pH-sensitive fluorescent proteins attached on nanoparticles (NPs) have been designed but inorganic NP-dependent fluorescent nanosensors have not yet been explored. Herein we describe a pH sensitive inorganic semiconductor fluorescent probe based on ultrathin 3C-SiC NPs which can effectively monitor pH in the range of 5.6-7.4 by taking advantage of the linear dependence between the fluorescent intensity ratio of the surface OH(-) and H(+) bonding states to band-to-band recombination and pH. Detection of pHi is demonstrated in living HeLa cells. In particular, pHi measurements during apoptosis confirm the validity and sensitivity of this technique in monitoring real-time changes in the intracellular environment. Toxicity assessment and confocal laser scanning microscopy indicate that the 3C-SiC NPs have low cytotoxicity and are compatible with living cells.
authors.affiliation: Department of Physics, NingBo Normal University, NingBo 315301, China.
authors.forename: Junhong
authors.initials: J
authors.lastname: Guo
authors.forename: Shijie
authors.initials: S
authors.lastname: Xiong
authors.forename: Xinglong
authors.initials: X
authors.lastname: Wu
authors.forename: Jiancang
authors.initials: J
authors.lastname: Shen
authors.forename: Paul K
authors.initials: PK
authors.lastname: Chu
mesh_terms: D017209:Apoptosis; D002138:Calibration; D017554:Carbon Compounds, Inorganic / Q000378:metabolism*; D004705:Endocytosis; D005452:Fluoresceins / Q000378:metabolism; D005453:Fluorescence; D005456:Fluorescent Dyes / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D006863:Hydrogen-Ion Concentration; D042541:Intracellular Space / Q000378:metabolism*; D053758:Nanoparticles / Q000737:chemistry* / Q000648:ultrastructure; D010316:Particle Size; D017655:Silicon Compounds / Q000378:metabolism*; D013050:Spectrometry, Fluorescence
chemical_list: D017554:Carbon Compounds, Inorganic; D005452:Fluoresceins; D005456:Fluorescent Dyes; D017655:Silicon Compounds; C043829:2',7'-bis(carboxyethyl)-5(6)-carboxyfluorescein; C022088:silicon carbide
keywords: Intracellular pH detection; Nanoparticles; Silicon carbide; pH-dependent photoluminescence