Urea-derived graphitic carbon nitride (u-g-C3N4) films with highly enhanced antimicrobial and sporicidal activity

Abstract

In this manuscript, we describe the fabrication of photoactive biocidal or sporicidal films from urea-derived graphitic carbon nitride (u-g-C3N4). Co-deposited films of u-g-C3N4 and Escherichia coli O157:H7 (IC50 = 14.1 ± 0.2 mJ) or Staphylococcus aureus (methicillin resistant IC50 = 33.5 ± 0.2 mJ, methicillin sensitive IC50 = 42.7 ± 0.5 mJ) demonstrated significantly enhanced bactericidal behavior upon administration of visible radiation (400 nm ≤ λ ≤ 426 nm). In all cases, complete eradication of the microbial sample was realized upon administration of 100 mJ of visible radiation, while no antimicrobial activity was observed for non-irradiated samples. In contrast, Bacillus anthracis endospores were more resistant to u-g-C3N4 mediated killing with only a ca. 25% reduction in spore viability when treated with a 200 mJ dose of visible radiation. Characterization of u-g-C3N4 reveals that the improved activity results from enhancements of both the surface area and reduction potential of the material’s conduction band edge, coupled with fast injection of charge carriers into localized states and a decline in radiative recombination events. The results of this study demonstrate that g-C3N4-based materials offer a viable scaffold for the development of new, visible light driven technologies for controlling potentially pathogenic microorganisms.

Two‐Dimensional Materials for Antimicrobial Applications: Graphene Materials and Beyond

“…However, in the above case, the most crucial role in bacterial inactivation is played by α‐S 8 , and g ‐C 3 N 4 only plays an auxiliary role. The real photocatalytic disinfection by using g ‐C 3 N 4 was achieved later . Zhao and co‐workers compared the different disinfection efficacy of bulk g ‐C 3 N 4 , g ‐C 3 N 4 nanosheets ( g ‐C 3 N 4 NS), and single‐layer g ‐C 3 N 4 (SL g ‐C 3 N 4 ), of which the SL g ‐C 3 N 4 showed the highest antibacterial activity (Figure f) because its 2D structure facilitated charge separation to produce photogenerated holes that dominate the bacterial inactivation ability .…”

“…The real photocatalytic disinfectionb yu sing g-C 3 N 4 was achieved later. [184][185][186][187] Zhao and coworkers compared the different disinfection efficacy of bulk g-C 3 N 4 , g-C 3 N 4 nanosheets (g-C 3 N 4 NS), and single-layer g-C 3 N 4 (SL g-C 3 N 4 ), of which the SL g-C 3 N 4 showed the highesta ntibacteriala ctivity (Figure 15f) because its 2D structure facilitated charges eparation to produce photogenerated holes that dominate the bacterial inactivation ability. [184] It was also confirmed by Huang et al that the photogenerated holes directly enhancet he oxidation of bacteria and thus lead to bacterial death.…”

Facile oxalic acid-assisted construction of laminated porous N-deficient graphitic carbon nitride: Highly efficient visible-light-driven hydrogen evolution photocatalyst

“…Especially, exploring a suitable synthetic method for g-C 3 N 4 to obtain ideal physicochemical properties is commonly deemed effective and forms the main part of this work. g-C 3 N 4 is originally prepared by direct calcination of pure precursors such as melamine [20] , cyanamine [21] and urea [22] . They usually have smaller specific surface areas and higher photogenerated electron-hole recombination rates, both of which limit the photocatalytic activity of the pristine g-C 3 N 4 .…”

Different inactivation behaviors and mechanisms of representative pathogens (Escherichia coli bacteria, human adenoviruses and Bacillus subtilis spores) in g-C3N4-based metal-free visible-light-enabled photocatalytic disinfection

“…MS2 bacteriophages and human adenoviruses) ( Li et al, 2016 ; Zhang et al, 2019c ), and spores (e.g. Bacillus anthracis endospores) ( Thurston et al, 2017 ) via the attack of photogenerated reactive oxidative species (ROS), attracting increasing interest as a low cost and environmentally friendly antimicrobial agent candidate for next-generation sustainable water disinfection.…”

“…To the best of our knowledge, there is no comprehensive comparative study on the antimicrobial performance of the g-C 3 N 4 /Vis process for a broad spectrum of pathogens, involving bacteria, human viruses, and spores. Also, a major issue in g-C 3 N 4 -based metal-free visible-light-enabled photocatalytic disinfection is its slow microbial inactivation kinetics due to the limited photocatalytic activity of pure g-C 3 N 4 and the strong environmental resistance of many pathogens (e.g., human adenoviruses and bacterial spores) ( Thurston et al, 2017 ; Zhang et al, 2020 ; Zhang et al, 2019c ). As a result, extensive efforts have been made to modify g-C 3 N 4 materials for enhanced photocatalytic disinfection performance ( Wang et al, 2013 ; Xia et al, 2020 ).…”