Aptamer-Modified Cu²⁺-Functionalized C-Dots: Versatile Means to Improve Nanozyme Activities-“Aptananozymes”

Abstract

The covalent linkage of aptamer binding sites to nanoparticle nanozymes is introduced as a versatile method to improve the catalytic activity of nanozymes by concentrating the reaction substrates at the catalytic nanozyme core, thereby emulating the binding and catalytic active-site functions of native enzymes. The concept is exemplified with the synthesis of Cu 2+ ion-functionalized carbon dots (C-dots), modified with the dopamine binding aptamer (DBA) or the tyrosinamide binding aptamer (TBA), for the catalyzed oxidation of dopamine to aminochrome by H 2 O 2 or the oxygenation of l -tyrosinamide to the catechol product, which is subsequently oxidized to amidodopachrome, in the presence of H 2 O 2 /ascorbate mixture. Sets of structurally functionalized DBA-modified Cu 2+ ion-functionalized C-dots or sets of structurally functionalized TBA-modified Cu 2+ ion-functionalized C-dots are introduced as nanozymes of superior catalytic activities (aptananozymes) toward the oxidation of dopamine or the oxygenation of l -tyrosinamide, respectively. The aptananozymes reveal enhanced catalytic activities as compared to the separated catalyst and respective aptamer constituents. The catalytic functions of the aptananozymes are controlled by the structure of the aptamer units linked to the Cu 2+ ion-functionalized C-dots. In addition, the aptananozyme shows chiroselective catalytic functions demonstrated by the chiroselective-catalyzed oxidation of l / d -DOPA to l / d -dopachrome. Binding studies of the substrates to the different aptananozymes and mechanistic studies associated with the catalytic transformations are discussed.

Nanozyme Catalytic Turnover and Self-Limited Reactions

“…Aside from Fe 3 O 4 NPs, over 40 types of peroxidase-mimicking nanozymes have been reported, , including various metal and metal oxide NPs, − carbon-based nanomaterials, − sulfide-based nanomaterials, − metal organic frameworks (MOFs), − and hybrid nanomaterials, − a combination of the categories aforementioned. The information presented in most of these works is limited, disallowing us to perform a similar in-depth analysis.…”

Au3+‐Functionalized UiO‐67 Metal‐Organic Framework Nanoparticles: O2•− and •OH Generating Nanozymes and Their Antibacterial Functions

“…For example, by the functionalization of C-dots nanozymes with β-cyclodextrins, chiralselective peroxidase activities were revealed, [22] and the modification of Cu 2+modified C-dots with aptamers enhanced peroxidase activities, and the oxidation of dopamine or hydroxylation of tyrosinamide, were demonstrated. [42] Different catalytic, enzyme-like, processes were driven by nanozymes including peroxidase, [43][44][45] oxidase, [46][47][48][49] catalase, [13,50] laccase, [51] superoxide dismutase, [52] hydrolase, [53,54] hydrogenase, [55] and more were demonstrated. Different applications of nanozymes were suggested including their use as sensors, [56][57][58][59][60] imaging agents, [61][62][63] catalysts in fuel cells, [64] and biomedical and therapeutic applications, such as cancer therapies, [65][66][67] Alzheimer's or Parkinson's diseases.…”

Chiral Carbon Dots Derived from Serine with Well-Defined Structure and Enantioselective Catalytic Activity

“…D-C-Dots are more effective to D-DOPA (k cat /K m , 2.65 × 10 −2 s −1 M −1 ) than L-DOPA (k cat /K m , 1.26 × 10 −2 s −1 M −1 ) with selectivity factor of 2.11. Although the chiral C-Dots could not specifically recognize and catalyze chiral substrates as natural enzymes or aptamer-modified material, 34 the selectivity factor (1.95−2.11) of the obtained chiral C-Dots is higher than the previously reported chiral nanomaterials with oxidase-like property (selectivity factor, 1.47−1.86), 32,33 demonstrating that the chiral C-Dots have great potential in chiral catalysis.…”