Construction And Application Of DNA-based Metallozymes

The practical application of natural enzymes is often hampered by its intrinsicdrawbacks, such as low stability, sensitivity of catalytic activity to environmentalconditions, and high costs in preparation and purification. Therefore, the discoveryand development of artificial enzymes is highly desired. Herein, based on theinteraction mechanism between polymorphic DNA and transition metal ion, twoDNA-based metalloenzymes are constructed to mimic peroxidase, and the key factorsof their enzyme-like activities are investigated.Firstly, a facile method is proposed to construct DNA-based peroxidase mimeticssimply assembled by polymorphic DNA and Cu2+ions. The reaction rates ofDNA-Cu(II) complexes are directly associated with sequence composition as well asthe secondary structure of DNA scaffold, e.g., the reaction rate decreases in thefollowing order: GpG-duplex≈G-rich coil> G-quadruplex> C-rich coil> i-motif. Acolorimetric Cu2+sensing system is explored on the basis of peroxidase mimickingactivities of polymorphic DNA-Cu(II) complexes. The GpG-duplex DNAdemonstrates the ability to sense Cu2+ions in aqueous solution without significantinterference from other metal ions. The Cu2+detection limit of1.2nM is achievedwith a linear response range of1.2~100nM, and the developed sensing system ispotentially applicable for quantitative determination of Cu2+in drinking watersamples.Secondly, G-/C-rich oligonucleotides are chosen as the nucleation templates tosynthesize Pt nanoclusters with the size distribution of1.7~2.9nm. The surfaceelectronic structures and particle sizes are greatly associated with the DNA templates,the Pt precursors as well as the molar ratios of [Pt]/[DNA]. The relative proportion ofPt0and Pt2+mainly contribute to the enzymatic activities of DNA-based Ptnanozymes. As the average size increases from1.8to2.9nm, the Kmvalue towardsH2O2decreases by three times, while towards TMB the Kmincreases by two times.The most efficient Pt nanozyme is stabilized by i-motif RET2with the average size of2.9nm. These results pave the way for manufacture metal nanozymes with facilemodulation of physicochemical properties through programming DNA sequences.