Xueping Tao,Mengting Su,Panpan Chen,Meiting Yan,Dan Wang,Lan Xia,Li Rao,Zhining Xia,Qifeng Fu
In recent years, mussel-inspired polydopamine (PDA)-based materials have attracted significant attention in the field of open-tubular capillary electrochromatography (OT-CEC) owing to their diverse and appealing properties. However, previously established functionalized PDA coating-based CEC stationary phases predominantly relied on the latent reactivity of PDA with amine/thiol-containing molecules, limiting the types of applicable modifiers and requiring time-consuming reaction processes. Herein, we presented a versatile and efficient method for the facile and rapid fabrication of diverse functionalized PDA coatings as OT-CEC stationary phases through a Zr(IV) coordination-mediated post-modification strategy. Different kinds of modifiers, including octadecylamine (ODA), lauric acid (LA), and perfluorooctanoic acid (PFOA), were rapidly and robustly grafted onto the PDA coating, verified through multiple characterization techniques. The influences of preparation parameters on the grafting efficiency of the functionalized PDA coating were systematically investigated. Utilizing the Zr(IV)-mediated ODA-, LA- and PFOA-functionalized PDA-based OT-CEC columns, we achieved high-efficiency baseline separation of a series of neutral analytes with excellent repeatability, good stability, and long lifetime. Given the strong universality of the Zr(IV) coordination-mediated post-modification approach, our study provides an effective pathway for advancing the development of a wider range of functional PDA-based chromatographic stationary phases.
The assay of kinase activity with ultrahigh sensitivity is important to medical diagnostics and drug discovery. Herein, we report the biologically mediated RAFT polymerization (BMRP) and its potential use as an efficient amplification strategy in the ultrasensitive electrochemical sensing of kinase activity. In BMRP, the reversible addition–fragmentation chain-transfer (RAFT) process is initiated and sustained by the reduced form of coenzyme I (i.e., NADH), which can efficiently mediate the direct fragmentation of thiocarbonylthio (TCT) compounds (or the TCT-capped dormant chains) to produce an initiating/propagating radical under mild conditions. Due to the absence of exogenous radicals, the notorious radical termination in RAFT equilibrium can be greatly suppressed. For the sensing of kinase activity, the recognition peptides, without carboxyl groups, are immobilized via the Au–S self-assembly. After phosphorylation, TCT compounds (as RAFT agents) are tethered to the enzymatically generated phosphate groups via the carboxylate-Zr(IV)-phosphate (CZP) linkage. Subsequently, the BMRP of ferrocenylmethyl methacrylate (FcMMA) results in the labeling of each phosphate group with hundreds to thousands of Fc tags, thereby greatly amplifying the sensing signal. Obviously, the BMRP-based strategy is biologically friendly, highly efficient, uncomplicated, and quite low-cost. The detection limit of 1.85 mU/mL has been achieved toward the selective sensing of the cAMP-dependent protein kinase (PKA). Moreover, the proposed kinase sensor is applicable to inhibitor screening and kinase activity sensing in serum samples. By virtue of its low cost, high sensitivity and selectivity, and uncomplicated operation, the proposed kinase sensor holds great potential in medical diagnostics and drug discovery.
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