[Show abstract][Hide abstract] ABSTRACT: Protein kinase plays a vital role in regulating signal-transduction pathways and its simple and quick detection is highly desirable because traditional kinase assays typically rely on a time-consuming kinase-phosphorylation process (ca. 1 h). Herein, we report a new and rapid fluorescence-based sensing platform for probing the activity of protein kinase that is based on the super-quenching capacity of graphene oxide (GO) nanosheets and specific recognition of the aptameric peptide (FITC-IP20 ). On the GO/peptide platform, the fluorescence quenching of FITC-IP20 that is adsorbed onto GO can be restored by selective binding of active protein kinase to the aptameric peptide, thereby resulting in the fast switch-on detection of kinase activity (ca. 15 min). The feasibility of this method has been demonstrated by the sensitive measurement of the activity of cAMP-dependent protein kinase (PKA), with a detection limit of 0.053 mU μL(-1) . This assay technique was also successfully applied to the detection of kinase activation in cell lysate.
Full-text · Article · Sep 2014 · Chemistry - An Asian Journal
[Show abstract][Hide abstract] ABSTRACT: Protein kinases are significant regulators in the cell signaling pathways, and it is still greatly desirable to achieve simple and quick kinase detection. Herein, we present a novel colorimetric gold nanoparticles (AuNPs)/peptide platform for probing the activity and inhibition of protein kinases based on phosphorylation-induced suppression of carboxypeptidase Y (CPY) cleavage. This AuNPs/peptide platform can easily monitor the kinase activity by a UV-vis spectrometer or even by the naked eye. The feasibility of the method has been demonstrated by sensitive measurement of the cAMP-dependent protein kinase (PKA) activity with a low detection limit of 0.232mU/µL and assessment of kinase inhibition by H-89 with an IC50 value of 18.13nM. The assay was also successfully put into practice for the detection of kinase activity in cell lysate. Because of its label-free, homogenous and colorimetric merits, the proposed assay presents great potential in high-throughput screening for kinase-targeted drug discovery.
Full-text · Article · Oct 2013 · Biosensors & Bioelectronics
[Show abstract][Hide abstract] ABSTRACT: A novel electrochemiluminescence (ECL) method for label-free detection of cancer cells was proposed for the first time by capturing negatively charged Jurkat cells onto Ru(bpy′)-immobilized indium tin oxide (ITO) electrode via electrostatic interaction. The ECL sensor exhibited excellent sensitivity, good stability and a linear response to Jurkat cells in the concentration range from 1×103 to 2×105 cells/mL, with a detection limit of 730 cells/mL. Furthermore, the method was successfully applied in the study of cell growth and cell apoptosis, which was supported by fluorescent images analysis. The proposed protocol is simple, rapid, inexpensive and universally targetable for tumors, offering a novel platform for the development of an ECL biosensor for cell detection.
[Show abstract][Hide abstract] ABSTRACT: The research on complicated kinomics and kinase-target drug discovery requires the development of simple, cost-effective, and multiplex kinase assays. Herein, we propose a novel and versatile biosensing platform for the detection of protein kinase activity based on graphene oxide (GO)-peptide nanocomplex and phosphorylation-induced suppression of carboxypeptidase Y (CPY) cleavage. Kinase-catalyzed phosphorylation protects the fluorophore-labeled peptide probe against CPY digestion and induces the formation of a GO/peptide nanocomplex resulting in fluorescence quenching, while the nonphosphopeptide is degraded by CPY to release free fluorophore as well as restore fluorescence. This GO-based nanosensor has been successfully applied to sensitively detect two model kinases, casein kinase (CKII) and cAMP-dependent protein kinase (PKA) with low detection limits of 0.0833 mU/μL and 0.134 mU/μL, respectively. The feasibility of this GO-based sensor was further demonstrated by the assessment of kinase inhibition by staurosporine and H-89, in vitro kinase assay in cell lysates, and simultaneous detection of CKII and PKA activity. Moreover, the GO-based fluorescence anisotropy (FA) kinase assay has been also developed using GO as a FA signal amplifier. The proposed sensor is homogeneous, facile, universal, label-free, and applicable for multiplexed kinase assay, presenting a promising method for kinase-related biochemical fundamental research and inhibitor screening.
No preview · Article · Jun 2013 · Analytical Chemistry
[Show abstract][Hide abstract] ABSTRACT: We report here an affinity separation-based fluorometric method for monitoring the activity and inhibition of protein kinase. In this assay, when the fluorescein isothiocyanate (FITC) labeled substrate peptides (S-peptide) are phosphorylated by kinase, the product peptides (P-peptide) will be adsorbed and concentrated onto the surface of Zr(4+)-immobilized nitrilotriacetic acid-coated magnetic nanoparticles (Zr-NTA MNPs) through the chelation of Zr(4+) and phosphate groups. After magnetic separation, the fluorescence intensity of the homogeneous solution changes dramatically. Hence the fluorescence response allows this MNPs-based method to easily probe kinase activity by a spectrometer. The feasibility of the method has been demonstrated by sensitive measurement of the activity of cAMP-dependent protein kinase (PKA) with a low detection limit (0.5mUμL(-1)). Moreover, the system is successfully applied to estimate the IC50 value of PKA inhibitor H-89 and detect the Forskolin/3-isobutyl-1-methylxanthine (IBMX) stimulated activation of PKA in cell lysate. Additionally, Zr-NTA MNPs are reusable by stripping Zr(4+) ions from NTA-coated MNPs and rechelating again. This method, which relies on the surface-functionalized MNPs, presents a promising candidate for simple and cost-effective assay of kinase activity and inhibitor screening.
No preview · Article · May 2013 · Analytica chimica acta
[Show abstract][Hide abstract] ABSTRACT: Protein kinases are significant regulators in the cell signal pathway, and it is difficult to achieve quick kinase detection because traditional kinase assays normally rely on a time-consuming kinase phosphorylation process. Herein, we present a novel one-step strategy to detect protein kinase by using a kinase-specific aptameric peptide-functionalized quartz crystal microbalance (QCM) electrode, in which the detection can be finished in less than 10 min. A peptide kinase inhibitor (IP(20)) was used as the aptameric peptide because of its selective and strong interaction with the target protein kinase (cyclic adenosine monophosphate-dependent protein kinase A, PKA), high stability, and ease of inexpensive synthesis, presenting a new direct recognition element for kinase. The aptameric peptide was immobilized on the Au-coated quartz electrode through dual-thiol anchoring and the binding of His-tagged peptide with a nitrilotriacetic acid/Ni(II) complex, fabricating a highly specific and stable detection platform. The interaction of aptameric peptide with kinase was monitored with the QCM in real time, and the concentration of protein kinase was sensitively measured by the frequency response of the QCM with the low detection limit for PKA at 0.061 mU μL(-1) and a linear range from 0.64 to 22.33 mU μL(-1). This method is rapid and reagentless and does not require a phosphorylation process. The versatility of our aptameric peptide-based strategy has also been demonstrated by the application in kinase assay using electrochemical impedance spectroscopy. Moreover, this method was successfully applied to detect the forskolin/3-isobutyl-1-methylxanthine-stimulated activation of PKA in cell lysate.
No preview · Article · Apr 2012 · Analytical Chemistry
[Show abstract][Hide abstract] ABSTRACT: A new label-free method for the detection of apoptosis was proposed based on colorimetric assay of caspase-3 activity using an unlabeled Asp-Glu-Val-Asp (DEVD)-containing peptide substrate and unmodified gold nanoparticles (AuNPs).
Full-text · Article · Dec 2011 · Chemical Communications
[Show abstract][Hide abstract] ABSTRACT: A novel method based on click chemistry for the immobilization of Ru(bpy)32+ derivative on electrode to fabricate a solid state electrochemiluminescence (ECL) sensor was reported. Pentenyl functionalized Ru(bpy′)3Cl2 was synthesized and immobilized on a (3-mercaptopropyl) trimethoxysilane (MPTMS) pretreated indium tin oxide (ITO) substrate via thiol-ene click chemistry reaction between its alkenyl group and the sulfhydryl group of MPTMS. The immobilization method is simple, fast, and efficient. More importantly, the resulting Ru(bpy′)32+ monolayer film exhibited excellent stability in organic solvent, which is superior to many previously reported methods. Using tri-n-propylamine (TPrA) as a model analyte, the ECL sensor gave a wide linear range over 5×10−6 to 5×10−3M, with a satisfactory detection limit of 1×10−6M (S/N=3).
No preview · Article · Dec 2011 · Electrochemistry Communications