title: Near Infrared Graphene Quantum Dots-Based Two-Photon Nanoprobe for Direct Bioimaging of Endogenous Ascorbic Acid in Living Cells.
abstract: Ascorbic acid (AA), as one of the most important vitamins, participates in various physiological reactions in the human body and is implicated with many diseases. Therefore, the development of effective methods for monitoring the AA level in living systems is of great significance. Up to date, various technologies have been developed for the detection of AA. However, few methods can realize the direct detection of endogenous AA in living cells. In this work, we for the first time reported that near-infrared (NIR) graphene quantum dots (GQD) possessed good two-photon fluorescence properties with a NIR emission at 660 nm upon exciting with 810 nm femtosecond pulses and a two-photon (TP) excitation action cross-section (δΦ) of 25.12 GM. They were then employed to construct a TP nanoprobe for detection and bioimaging of endogenous AA in living cells. In this nanosystem, NIR GQDs (NGs), which exhibited lower fluorescence background in living system to afford improved fluorescence imaging resolution, were acted as fluorescence reporters. Also CoOOH nanoflakes were chosen as fluorescence quenchers by forming on the surface of NGs. Once AA was introduced, CoOOH was reduced to Co2+, which resulted in a "turn-on" fluorescence signal of NGs. The proposed nanoprobe demonstrated high sensitivity toward AA, with the observed LOD of 270 nM. It also showed high selectivity to AA with excellent photostability. Moreover, the nanoprobe was successfully used for TP imaging of endogenous AA in living cells as well as deep tissue imaging.
authors.affiliation: Molecular Science and Biomedicine Laboratory, State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Collaborative Innovation Center for Chemistry and Molecular Medicine, Hunan University , Changsha 410082, China.
authors.forename: Li-Li
authors.initials: LL
authors.lastname: Feng
authors.affiliation: Molecular Science and Biomedicine Laboratory, State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Collaborative Innovation Center for Chemistry and Molecular Medicine, Hunan University , Changsha 410082, China.
authors.forename: Yong-Xiang
authors.initials: YX
authors.lastname: Wu
authors.affiliation: Molecular Science and Biomedicine Laboratory, State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Collaborative Innovation Center for Chemistry and Molecular Medicine, Hunan University , Changsha 410082, China.
authors.forename: Dai-Liang
authors.initials: DL
authors.lastname: Zhang
authors.affiliation: Molecular Science and Biomedicine Laboratory, State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Collaborative Innovation Center for Chemistry and Molecular Medicine, Hunan University , Changsha 410082, China.
authors.forename: Xiao-Xiao
authors.initials: XX
authors.lastname: Hu
authors.affiliation: Molecular Science and Biomedicine Laboratory, State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Collaborative Innovation Center for Chemistry and Molecular Medicine, Hunan University , Changsha 410082, China.
authors.forename: Jing
authors.initials: J
authors.lastname: Zhang
authors.affiliation: Molecular Science and Biomedicine Laboratory, State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Collaborative Innovation Center for Chemistry and Molecular Medicine, Hunan University , Changsha 410082, China.
authors.forename: Peng
authors.initials: P
authors.lastname: Wang
authors.affiliation: Key Laboratory of Sensor Analysis of Tumor Marker, Ministry of Education, College of Chemistry and Molecular Engineering, Qingdao University of Science and Technology , Qingdao 266042, China.
authors.forename: Zhi-Ling
authors.initials: ZL
authors.lastname: Song
authors.affiliation: Molecular Science and Biomedicine Laboratory, State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Collaborative Innovation Center for Chemistry and Molecular Medicine, Hunan University , Changsha 410082, China.
authors.forename: Xiao-Bing
authors.identifier: 0000-0002-4010-0028
authors.initials: XB
authors.lastname: Zhang
authors.affiliation: Molecular Science and Biomedicine Laboratory, State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Collaborative Innovation Center for Chemistry and Molecular Medicine, Hunan University , Changsha 410082, China.
authors.forename: Weihong
authors.identifier: 0000-0002-8066-1524
authors.initials: W
authors.lastname: Tan
mesh_terms: D001205:Ascorbic Acid / Q000032:analysis*; D005456:Fluorescent Dyes / Q000737:chemistry*; D006108:Graphite / Q000737:chemistry*; D006367:HeLa Cells; D006801:Humans; D053758:Nanoparticles / Q000737:chemistry*; D061848:Optical Imaging; D010316:Particle Size; D017785:Photons; D045663:Quantum Dots / Q000737:chemistry*; D013499:Surface Properties
chemical_list: D005456:Fluorescent Dyes; D006108:Graphite; D001205:Ascorbic Acid