Abstract
Nitrogen-functionalization is an effective means of improving the catalytic performances of nanozymes. In the present work, plasma-assisted nitrogen modification of nanocolumnar Ni GLAD films was performed using an ammonia plasma, resulting in an improvement in the peroxidase-like catalytic performance of the porous, nanostructured Ni films. The plasma-treated nanozymes were characterized by TEM, SEM, XRD, and XPS, revealing a nitrogen-rich surface composition. Increased surface wettability was observed after ammonia plasma treatment, and the resulting nitrogen-functionalized Ni GLAD films presented dramatically enhanced peroxidase-like catalytic activity. The optimal time for plasma treatment was determined to be 120 s; when used to catalyze the oxidation of the colorimetric substrate TMB in the presence of H2O2, Ni films subjected to 120 s of plasma treatment yielded a much higher maximum reaction velocity (3.7⊆10−8 M/s vs. 2.3⊆10−8 M/s) and lower Michaelis-Menten coefficient (0.17 mM vs. 0.23 mM) than pristine Ni films with the same morphology. Additionally, we demonstrate the application of the nanozyme in a gravity-driven, continuous catalytic reaction device. Such a controllable plasma treatment strategy may open a new door toward surface-functionalized nanozymes with improved catalytic performance and potential applications in flow-driven point-of-care devices.
Highlights
Enzymes are complex biological structures that play key roles in metabolic activities and catalyze numerous biological reactions with excellent catalytic activity, efficiency, and selectivity
We utilize the plasma-modified and pristine Ni films to catalyze the oxidation of Tetramethyl benzidine (TMB) by H2O2, and we show that the N-functionalized films present enhanced catalytic reaction rates
No significant morphology changes were identified by scanning electron microscopy (SEM) following plasma treatment (S1 Fig), indicating that the plasma processing does not strongly affect the film morphology and associated surface area
Summary
Enzymes are complex biological structures that play key roles in metabolic activities and catalyze numerous biological reactions with excellent catalytic activity, efficiency, and selectivity. These natural enzymes, generally require well-controlled reaction conditions (temperature, pH, purity, etc.) [1], and outside of the human body, precisely controlling these operation and storage conditions can be very difficult, which limits commercial applications [2]. Artificial enzymes known as “nanozymes” are nanomaterials with enzyme-like characteristics [3, 4]. Nanozymes have attracted enormous research interest in recent years for their unique advantages
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