Advanced Selection Methodologies for DNAzymes in Sensing and Healthcare Applications

Techniques for the selection of DNAzymes via SELEX approaches include microfluidics, nanoselection, hi-fidelity, isogenic, and automated. DNAzymes are able to catalyze chemical reactions with high activity and selectivity. DNAzymes have applications in sensing, catalysis, and healthcare. DNAzyme-based biosensors typically use RNA-cleavage and G-quadruplex DNAzymes. Suppression of cancer-related genes is an important target of DNAzymes. DNAzymes may be used as theranostic agents with dual utility in diagnosis and treatment. DNAzymes have been widely explored owing to their excellent catalytic activity in a broad range of applications, notably in sensing and biomedical devices. These newly discovered applications have built high hopes for designing novel catalytic DNAzymes. However, the selection of efficient DNAzymes is a challenging process but one that is of crucial importance. Initially, systemic evolution of ligands by exponential enrichment (SELEX) was a labor-intensive and time-consuming process, but recent advances have accelerated the automated generation of DNAzyme molecules. This review summarizes recent advances in SELEX that improve the affinity and specificity of DNAzymes. The thriving generation of new DNAzymes is expected to open the door to several healthcare applications. Therefore, a significant portion of this review is dedicated to various biological applications of DNAzymes, such as sensing, therapeutics, and nanodevices. In addition, discussion is further extended to the barriers encountered for the real-life application of these DNAzymes to provide a foundation for future research. DNAzymes have been widely explored owing to their excellent catalytic activity in a broad range of applications, notably in sensing and biomedical devices. These newly discovered applications have built high hopes for designing novel catalytic DNAzymes. However, the selection of efficient DNAzymes is a challenging process but one that is of crucial importance. Initially, systemic evolution of ligands by exponential enrichment (SELEX) was a labor-intensive and time-consuming process, but recent advances have accelerated the automated generation of DNAzyme molecules. This review summarizes recent advances in SELEX that improve the affinity and specificity of DNAzymes. The thriving generation of new DNAzymes is expected to open the door to several healthcare applications. Therefore, a significant portion of this review is dedicated to various biological applications of DNAzymes, such as sensing, therapeutics, and nanodevices. In addition, discussion is further extended to the barriers encountered for the real-life application of these DNAzymes to provide a foundation for future research. a technique used for the physical separation of mixtures into their components. All forms of chromatography work on the same principle, in that, all have a stationary phase and a mobile phase. The approach is well-known for its high sensitivity because of competitive interaction between the desired molecule and target immobilized stationary phase that are mainly composed of agarose beads. synthetic method used to prepare a library of structurally related analogues in a single process. Currently, vast ranges of simulation software are used for generating combinatorial library. the basic principle of electrochemical biosensors involves immobilization of selected functional DNA molecules on an electrode surface that specifically bind to a ligand, which can further lead to a change in the current or voltage. analysis technique used to efficiently separate charged particles from each another based on differences in their mobility. It can be used to separate a variety of small and large target molecules. The major shortcoming associated is that the target molecule should have a sufficient size to induce mobility changes. single-stranded G-rich aptamer sequences spontaneously form an intramolecular four-stranded helical structure (G4). Associates with the hemin group to form the catalytic G4-hemin-DNAzyme complex. This complex DNAzyme catalyzes the oxidation reaction of hydrogen peroxide to result in the generation of chemiluminescence. a logic gate performs a logical operation (Boolean algebra) on given inputs in order to generate a single electrical output. Different logic gates are combined using combinatorial or sequential approaches for computer programming. Basic logic gate series include-AND, OR, NOT, XOR, NOR, NAND, and XNOR. enzymes that require metal ions as cofactors for their catalytic activity. Although the metal cannot be bound in a permanent way to the enzyme, it is bound firmly to a specific region of the native conformation of the protein. it is a fundamental equation for enzyme kinetics that relates rate of reactions [V], to substrate concentration [S] i.e., V = Kcat [Enzyme] [S]/(Km + [S]). polymerase chain reaction is a molecular technique used to exponentially amplify segments of a particular DNA sequence into millions or billions of copies. The strategy involves incorporation of a PCR primer and DNA polymerase with a template strand. The method has a major limitation in that it may give false positive results. RNA molecule based regulatory system. Directs enzyme complexes to degrade mRNA molecules. Different categories of these molecules include miRNA, small interfering RNA (siRNA), and small hairpin RNA (shRNA). 2D or 3D structures attained by single-stranded nucleic acid through the use of hydrogen bonds. Stem loops, hairpins, tetraloops, and pseudo-knots are the most well-known conformations in the context of catalytic molecules. SELEX also known as 'selected and amplified binding site' (SAAB) and 'cyclic amplification and selection of targets' (CASTing) is an 'in vitro selection' method used for the isolation of DNA based catalytic molecules. It is an iterative method that includes selection, separation, and amplification of desired molecules. is an emerging field that deals with both imaging and therapeutics in one step. Initially, it was used only for nanomaterials as they are widely explored as both imaging agents and pharmaceutical agents, but now this has been expanded to other novel materials. oligonucleotide probes with altered sugar backbones have been discovered and named xenonucleic acids (XNAs). These XNA molecules were synthesized directly from DNA templates but replicated by means of specially engineered mutant polymerases. These polymerases introduced errors, thereby producing novel XNA sequences catalyzing reactions termed as XNAzymes.