An amplified electrochemical aptasensor for ochratoxin A based on DNAzyme-mediated DNA walker

Application of Nanomaterial Modified Aptamer-Based Electrochemical Sensor in Detection of Heavy Metal Ions

Heavy metal pollution resulting from significant heavy metal waste discharge is increasingly serious. Traditional methods for the detection of heavy metal ions have high requirements on external conditions, so developing a sensitive, simple, and reproducible detection method is becoming an urgent need. The aptamer, as a new kind of artificial probe, has received more attention in recent years for its high sensitivity, easy acquisition, wide target range, and wide use in the detection of various harmful substances. The detection platform that an aptamer-based electrochemical biosensor (E-apt sensor) provides is a new approach for the detection of heavy metal ions. Nanomaterials are particularly important in the construction of E-apt sensors, as they can be used as aptamer carriers or sensitizers to stimulate or inhibit electrochemical signals, thus significantly improving the detection sensitivity. This review summarizes the application of different types of nanomaterials in E-apt sensors. The construction methods and research progress of the E-apt sensor based on different working principles are systematically introduced. Moreover, the advantages and challenges of the E-apt sensor in heavy metal ion detection are summarized.

Selection of M2+-independent RNA-cleaving DNAzymes with Sidechains Mimicking Arginine and Lysine

Sequence-specific cleavage of RNA by nucleic acid catalysts in the absence of a divalent metal cation (M 2+ ) has remained an important goal in biomimicry with potential therapeutic applications. Given the lack of functional group diversity in canonical nucleotides, modified nucleotides with amino acid-like side chains were used to enhance self-cleavage rates at a single embedded ribonucleoside site. Previous works relied on three functional groups: an amine, a guanidine and an imidazole ensconced on three different nucleosides. However, to date, few studies have systematically addressed the necessity of all three modifications, as the value of any single modified nucleoside is contextualized at the outset of selection. Herein, we report on the use of only two modified dNTPs, excluding an imidazole, i.e. 5-(3-guanidinoallyl)-2'-dUTP (dU ga TP) and 5-aminoallyl-2'-dCTP (dC aa TP), to select in-vitro self-cleaving DNAzymes that cleave in the absence of M 2+ in a pH-independent fashion. Cleavage shows biphasic kinetics with rate constants that are significantly higher than in unmodified DNAzymes and compare favorably to certain DNAzymes involving an imidazole. This work is the first report of a M2+-independent DNAzyme with two cationic modifications; as such it shows appreciable self-cleaving activity in the absence of an imidazole modification.