Peroxidyme‐Amplified Radical Chain Reaction (PARCR): Visible Detection of a Catalytic Reporter

Abstract

Peroxidyme Amplified Radical Chain Reaction (PARCR), anovel enzyme-free system that achieves exponential amplification of av isible signal, is presented. Typical enzyme-free amplification systems that produce avisible readout suffer from long reaction times,low sensitivity,and narrow dynamic range.P ARCR employs photocatalyzed nonlinear signal generation, enabling unprecedented one-pot, naked-eye detection of acatalytic reporter from 1 mm down to 100 pm.In this reaction, hemin-binding peroxidase-mimicking DNAzymes ("peroxidymes") mediate the NADH-driven oxidation of acolorless,nonfluorescent phenoxazine dye (Amplex Red) to abrightly colored, strongly fluorescent product (resorufin); illumination with green light initiates multiple radical-forming positive-feedbackl oops,r apidly producing visible levels of resorufin. Collectively,t hese results demonstrate the potential of PARCR as an easy-to-use readout for ar ange of detection schemes,i ncluding aptamer labels,h ybridization assays,a nd nucleic acid amplification.

A Push–Pull Mechanism Helps Design Highly Competent G-Quadruplex-DNA Catalysts

“…[8][9][10][11][12] The current popularity of G4-DNAzymes stems from the versatile designability [13][14][15][16][17] and excellent biocompatibility of G4 precatalysts. [18][19][20][21] Unfortunately, the performances of G4-DNAzymes are still below those of corresponding enzymes, leading to new research and strategies for improved performance. To date, optimization strategies can be divided into two types: the addition of exogenous activators, [22][23][24][25][26][27][28][29] such as spermine, 22 cytidine triphosphate (CTP), 23 adenine triphosphate (ATP), [23][24][25] templateassembled synthetic G-quartet (TASQ), 26 and self-assembling peptides [27][28][29] on one side, and the modification of the G4 structure [30][31][32][33][34][35] to provide hemin with a more defined and suited binding pocket 31,32 or hemin itself 36,37 on the other side.…”