Subscriber access provided by Loyola University Libraries
Article
Using Graphene Quantum Dots as Novel Photoluminescent Probes for Protein Kinase Sensing Ying Wang, Li Zhang, Ru-Ping Liang, Jian-Mei Bai, and Jian-Ding Qiu Anal. Chem., Just Accepted Manuscript • DOI: 10.1021/ac401807b • Publication Date (Web): 05 Sep 2013 Downloaded from http://pubs.acs.org on September 18, 2013
Just Accepted “Just Accepted” manuscripts have been peer-reviewed and accepted for publication. They are posted online prior to technical editing, formatting for publication and author proofing. The American Chemical Society provides “Just Accepted” as a free service to the research community to expedite the dissemination of scientific material as soon as possible after acceptance. “Just Accepted” manuscripts appear in full in PDF format accompanied by an HTML abstract. “Just Accepted” manuscripts have been fully peer reviewed, but should not be considered the official version of record. They are accessible to all readers and citable by the Digital Object Identifier (DOI®). “Just Accepted” is an optional service offered to authors. Therefore, the “Just Accepted” Web site may not include all articles that will be published in the journal. After a manuscript is technically edited and formatted, it will be removed from the “Just Accepted” Web site and published as an ASAP article. Note that technical editing may introduce minor changes to the manuscript text and/or graphics which could affect content, and all legal disclaimers and ethical guidelines that apply to the journal pertain. ACS cannot be held responsible for errors or consequences arising from the use of information contained in these “Just Accepted” manuscripts.
Analytical Chemistry is published by the American Chemical Society. 1155 Sixteenth Street N.W., Washington, DC 20036 Published by American Chemical Society. Copyright © American Chemical Society. However, no copyright claim is made to original U.S. Government works, or works produced by employees of any Commonwealth realm Crown government in the course of their duties.
Page 1 of 23
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
Analytical Chemistry
Using Graphene Quantum Dots as Novel Photoluminescent Probes for Protein Kinase Sensing Ying Wang, Li Zhang, Ru-Ping Liang, Jian-Mei Bai, Jian-Ding Qiu* Department of Chemistry, Nanchang University, Nanchang 330031, P. R. China
*Corresponding author Jian-Ding Qiu Department of Chemistry, Nanchang University, Nanchang 330031, P. R. China Phone: +86-791-8396-9518 ; Fax: +86-791-8396-9518; E-mail:
[email protected] ACS Paragon Plus Environment
1
Analytical Chemistry
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
Page 2 of 23
ABSTRACT A simple and sensitive photoluminescence (PL) assay for the activity of protein kinase was established based on the selective aggregation of phosphorylated peptide-graphene quantum dots (GQDs) conjugates triggered by Zr4+ ions coordination. With more sophisticated design on the peptide substrate sequences, detecting other enzymes could also be possible. Under optimal conditions, a linear relationship between the decreased PL intensity of peptide-GQDs and the concentration of casein kinase II (CK2) in the range from 0.1 U mL-1 to 1.0 U mL-1 with a detection limit of 0.03 U mL-1 (3σ) was obtained. The EC50 value (enzyme concentration at which 50% substrate is converted) of CK2 was evaluated to be 0.34 U mL-1. The proposed method showed potential applications in kinase inhibitor screening. To demonstrate the potential of this GQDs-based platform for screening kinase inhibitors in real biological systems, the inhibition of CK2 phosphorylation activity by four different inhibitors, ellagic acid, 5,6Dichloroben-zimidazole-l-β-D-ribofuranoside (DRB), emodin, and quercetin, was tested in human serum by comparing signals from samples incubated with inhibitors against that without any inhibitor. As expected, in the presence of inhibitors, the PL intensity increased with the increasing efficiency of inhibitor. The IC50 value (inhibitor concentration producing 50% inhibition) of ellagic acid was estimated to be 0.041 µM. The developed protocol provided a new and promising tool for the analysis of both enzyme and its inhibitors with low cost and excellent performance.
KEYWORDS: protein kinase, graphene quantum dot, photoluminescence quenching, inhibitor.
ACS Paragon Plus Environment
2
Page 3 of 23
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
Analytical Chemistry
INTRODUCTION Graphene, a two-dimensional carbon material, has sparked great excitement within the scientific community due to its fascinating and unusual physical and chemical properties.1,2 Nevertheless, as graphene is a zero-bandgap semiconductor, the possibility of observing its luminescence is highly unlikely,3 and its optoelectronic applications have so far been limited. To generate an electronic band gap in graphene, various methods such as opening the bandgap through doping,4 manipulating graphene oxide (GO) through partial reduction and surface passivation,5,6 and cleaving GO materials into nanoscale graphene quantum dots (GQDs)7,8 have been used to induce photoluminescence (PL). Among them, the GQDs fabrication and the tuning of their optical properties have become the most active area. In theoretical and experimental studies, GQDs with
