Sub-Second Electrochemiluminescence Imaging Assay of SARS-CoV-2 Nucleocapsid Protein Based on Reticulation of Endo-Coreactants.

The nonphotodriven electrochemiluminescence (ECL) imageology necessitates concentrated coreacting additives plus longtime exposures. Seeking biosafe and streamlined ensembles can help lower the bar for quality ECL bioimaging to which call the crystallized endo-coreaction in nanoreticula might provide a potent solution. Herein, an exo-coreactant-free ECL visualizer was fabricated out in one-pot, which densified the dyad triethylamine analogue: 1,4-diazabicyclo-[2.2.2]octane (DABCO) in the lamellar hive of 9,10-di(p-carboxyphenyl)anthracene (DPA)-Zn2+. This biligated non-noble metal-organic framework (m-MOF) facilitated a self-contained anodic ECL with a yield as much as 70% of Ru(bPy)32+ in blank phosphate buffered saline. Its featured two-stage emissions rendered an efficient and endurant CCD imaging at 1.0 V under mere 0.5 s swift snapshots and 0.1 s step-pulsed stimulation. Upon structural and spectral cause analyses as well as parametric set optimization, simplistic ECL-graphic immunoassay was mounted in the in situ imager to enact an ultrasensitive measurement of coronaviral N-protein in both signal-on and off modes by the privilege of straight surface amidation on m-MOFs, resulting in a wide dynamic range (10-4-10 ng/mL), a competent detection limit down to 56 fg/mL, along with nice precision and parallelism in human saliva tests. The overall work manifests a rudimentary endeavor in self-sufficient ECL visuality for brisk, biocompatible, and brilliant production of point-of-care diagnostic "Big Data".

Ligand-binding assay based on microfluidic chemotaxis of porphyrin receptors.

Recent studies have shown that enzymes undergo chemotaxis up substrate gradients during catalysis. One important avenue to identify the molecular level origins of this phenomenon is the ligand-protein binding that occurs even in the absence of catalytic turnover. Here, the chemotaxis of zinc porphyrin as a cofactor mimic was observed by imposing a concentration gradient of organic amines in the microfluidic device. Their axial ligations led to the directed motions of porphyrin receptors. The dissociation constant for selected recognition could be obtained by measuring the chemotactic shift as a function of ligand content, which is associated with both the binding strength and the steric hindrance of the specific ligand. Finally, a statistical thermodynamic model was derived, relating the change of Gibbs free energy (ΔG) in the binding process to the directional migration of receptors. The theoretical model agreed quantitatively with experimental results, elucidating that ΔG of reversible binding essentially drives molecular chemotaxis.