Intrinsic Light-Activated Oxidase Mimicking Activity of Conductive Polyaniline Nanofibers: A Class of Metal-Free Nanozyme

Abstract

In recent decades, studies have focused on inorganic nanozymes to overcome the intrinsic drawbacks of bioenzymes due to the demands of improving the reaction conditions and lack of robustness to harsh environmental factors. Many biochemical reactions catalyzed by enzymes require light activation. Light-activated nanozymes have distinct advantages, including being regulated by light stimuli, activating the molecular oxygen to produce reactive oxygen species (ROS) without interfering supplementary oxidants, and often showing a synergistic effect to catalyze some challenging reactions. Only a few studies have been done on this connection. Therefore, it is still a big challenge to develop a nanozyme regulated by light activation. Herein, we uncovered the light-activated oxidase mimicking activity of a conducting polymer polyaniline nanofibers (PANI-NFs). PANI-NFs exhibit intrinsic lightactivated brilliant oxidase-like activity, can catalyze the colorless tetramethyl benzidine (TMB) to produce a blue product TMBox, and have a distinct K m = 0.087 mM and a high V max = 2.32 μM min −1 value, measured by using Hanes−Woolf kinetics. We also report the light-activated oxidase activity of some other renowned carbocatalysts graphene oxide and graphitic carbon nitride and compare them with PANI-NFs. This type of property shown by the conductive polymer is amazing. The density functional theory is used to verify the stability and the mode of adsorption of the PANI NFs-TMB composite, which corroborates the experimental results. Furthermore, the current nanozyme demonstrated a significant ability to kill both Gram-negative and Gram-positive bacteria as well as effectively destroy biofilms under physiological conditions. We believe that this work provides the motivation to create a link between optoelectronics and biological activity in the near future.

Rational synthesis and characterization of temperature switching ZnFe2O4/ZnO nanocomposites used for anti-bacterial, anti-oxidant and seed germination properties

“…84 The O–H bending vibrational mode for moisture leads to the appearance of a peak in the 1629–1631 cm −1 range. 83 So, the peak became less intense with the increase in calcination temperature. Additionally, two peaks corresponding to the C–H bending vibrational bands at 1384 cm −1 and the CH 2 scissoring band at 1468 cm −1 were observed.…”

“…4 presents the FTIR spectra of the nanocomposites and the broad peak for all the composites at wavenumber 3400-3430 cm À1 arises from O-H stretching due to H 2 O molecules. 83 The asymmetric stretching and stretching vibrations of -CH 2 -in aliphatic chains are responsible for two small, sharp peaks at 2920 cm À1 and 2850 cm À1 . 84 The O-H bending vibrational mode for moisture leads to the appearance of a peak in the 1629-1631 cm À1 range.…”

Synthesis of Spherical Mn2O3 Nanozymes from Different Green Precursors for their Innovative Applications in Catalytic Properties and Bioactivity

“…The color changes from blue to green and then to yellow when the pH of the solution decreases; this may be due to TMB-diimine formation at acidic pH. TMB-diimine is produced by two-electron-transfer oxidation Figure B shows the time-dependent oxidase-mimicking activity; the absorbance increases with increasing time and reaches the maximum at 5 min and then remains constant; therefore, 5 min was considered as the optimum time for the present oxidation reaction.…”

“…TMB-diimine is produced by two-electron-transfer oxidation. 32 Figure 3B shows the time-dependent oxidase-mimicking activity; the absorbance increases with increasing time and reaches the maximum at 5 min and then remains constant; therefore, 5 min was considered as the optimum time for the present oxidation reaction. Therefore, the optimum conditions for the best activity were considered at pH 5 at 5 min and room temperature.…”

Nanozymes with biomimetically designed properties for cancer treatment

“…Combining the characteristics of nanomaterials, they can mediate changes in enzyme-like catalytic reactions based on physicochemical factors such as pH, temperature, light, or magnetism. [108][109][110][111] Moreover, ideally, these nanozymes are designed to be highly selective, and activated by specific triggers related to the TME or external stimuli. This targeted approach enables them to precisely attack tumors or specific cancer cells, thus reducing the possibility of damaging healthy cells or tissues.…”