Comparison of DNAzyme activity for the development of an immobilized heme sensor
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MRS Advances © 2017 Materials Research Society DOI: 10.1557/adv.2017.637
Comparison of DNAzyme activity for the development of an immobilized heme sensor Natalie Hughes1, Nancy Nguyen1, Deanna-Kaye Daley1, Justin Grennell1, Amira Gee1 and Mehnaaz F. Ali1 1
Department of Chemistry,
Xavier University of Louisiana, 1, Drexel Drive, New Orleans LA 70125
ABSTRACT
Point-of-care systems require highly sensitive, quantitative and selective detection platforms for the real-time multiplexed monitoring of target analytes. To ensure facile development of a sensor, it is preferable for the detection assay to have minimal chemical complexity, contain no wash steps and provide a wide and easily adaptable detection range for multiple targets. Current studies involve label-free detection strategy for relevant clinical molecules such as heme using G-quadruplex based self-assembly. We have explored the measurement of binding and kinetic parameters of various Gquadruplex/heme complexes which are able to self-associate to form a DNAzyme with peroxidase mimicking capabilities and are critical to nucleic acid research. The detection strategy includes immobilizing the G-quadruplex sequences within a polymer matrix to provide a self-assembly based detection approach for heme that could be translated towards other clinically relevant targets. INTRODUCTION G-quadruplexes (G-quad) are stable structures formed via Hoogsteen hydrogen bonding between guanine bases in guanine rich DNA sequences.[1, 2] These interactions form tetrads that stack in a planar arrangement forming the Gquad. The amount of research that has explored G-quads has increased due to studies showing the importance of guanine-rich oligonucleotides, that can form a G-quad structure, modulating cellular processes such as replication, gene regulation, recombination and epigenetics.[3] DNA G-quad have also been widely involved in many functional DNAs and have been critical for their catalytic and target recognition activities. One such feature of G-quads is their ability to mimic peroxidase-like activity and form a DNAzyme. The underlying principal is dependent on the formation of a complex between a G-quad and hemin which can catalyze a H2O2
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mediated oxidation of a peroxidase substrate. These sequences (with peroxidase-like ability) have been identified either via in vitro selection or traditional aptamer selection methods. The present study explores the different enzymatic activities of different DNAzymes present in the literature. Previous work has demonstrated that the strongest hemin-binding affinity was related to the best DNAzyme activity.[4] In addition, the binding of heme with the G-quad showing the highest activities are further probed using isothermal calorimetry. These studies culminate towards developing a sensor for fre
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