title: One-step synthesis of biofunctional carbon quantum dots for bacterial labeling.
abstract: In this study, we used a simple one-step dry heating method to synthesize mannose-modified fluorescent carbon quantum dots (Man-CQDs) from solid ammonium citrate and mannose, and successfully applied for labeling Escherichia coli. The highly soluble Man-CQDs had an average particle diameter of 3.1±1.2 nm and exhibited a quantum yield of 9.8% at excitation and emission wavelengths of 365 and 450 nm, respectively. The fluorescent Man-CQDs could selectively bind to the FimH lectin unit in the flagella of the wild-type 1 E. coli K12 strain. We optimized the labeling efficiency of the Man-CQDs by controlling the ratio of ammonium citrate to mannose during their synthesis. The specific binding of the mannose units to E. coli allowed quantitative detection of the bacteria at levels down to 450 colony forming units mL(-1) in lab samples, and facilitate the application of the Man-CQDs for bacterial analyses of real samples (tap water, apple juice, human urine). The synthesis of our Man-CQDs, their labeling, and their use in the detection of bacteria were all simple, inexpensive and efficient processes.
authors.affiliation: Department of Bioscience and Biotechnology, NationalTaiwan Ocean University, 2, Pei-Ning Road, Keelung 20224, Taiwan.
authors.forename: Cheng-I
authors.initials: CI
authors.lastname: Weng
authors.affiliation: Department of Chemistry, National Taiwan University, Taipei 10617, Taiwan.
authors.forename: Huan-Tsung
authors.initials: HT
authors.lastname: Chang
authors.affiliation: Key Laboratory of Nano-Bio Interface, Suzhou Key Laboratory for Nanotheranostics, Division of Nanobiomedicine, Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences, Suzhou 215123, China.
authors.forename: Chia-Hua
authors.initials: CH
authors.lastname: Lin
authors.affiliation: Department of Bioscience and Biotechnology, NationalTaiwan Ocean University, 2, Pei-Ning Road, Keelung 20224, Taiwan.
authors.forename: Yu-Wei
authors.initials: YW
authors.lastname: Shen
authors.affiliation: Department of Bioscience and Biotechnology, NationalTaiwan Ocean University, 2, Pei-Ning Road, Keelung 20224, Taiwan.
authors.forename: Binesh
authors.initials: B
authors.lastname: Unnikrishnan
authors.affiliation: Department of Bioscience and Biotechnology, NationalTaiwan Ocean University, 2, Pei-Ning Road, Keelung 20224, Taiwan.
authors.forename: Yu-Jia
authors.initials: YJ
authors.lastname: Li
authors.affiliation: Department of Bioscience and Biotechnology, NationalTaiwan Ocean University, 2, Pei-Ning Road, Keelung 20224, Taiwan; Center of Excellence for the Oceans, National Taiwan Ocean University, Keelung, Taiwan; School of Pharmacy, College of Pharmacy, Kaohsiung Medical University, Kaohsiung 80708, Taiwan. Electronic address: huanging@ntou.edu.tw.
authors.forename: Chih-Ching
authors.initials: CC
authors.lastname: Huang
mesh_terms: D015374:Biosensing Techniques; D002244:Carbon / Q000737:chemistry; D019343:Citric Acid / Q000737:chemistry; D004926:Escherichia coli / Q000302:isolation & purification*; D006801:Humans; D008358:Mannose / Q000138:chemical synthesis / Q000737:chemistry; D045663:Quantum Dots / Q000737:chemistry*; D000644:Quaternary Ammonium Compounds / Q000737:chemistry; D013194:Staining and Labeling
chemical_list: D000644:Quaternary Ammonium Compounds; D019343:Citric Acid; D002244:Carbon; C481046:ammonium citrate; D008358:Mannose
keywords: Bacterial labeling; Carbon quantum dots; E. coli; Lectin; Mannose