Polyvinyl alcohol/chitosan nanofiber membranes loaded with oxygenated graphitic carbon nitride nanosheets for enhanced photocatalytic bacteriostasis

Abstract

The visible light catalytic antibacterial nanofiber membranes as a novel functional material were designed to solve the problem of bacterial infection and water pollution. In this work, oxygenated graphite carbon nitride nanosheets (O‐g‐C3N4) with 12% oxygen content were synthesized through thermal polycondensation followed by chemical oxidation. Exfoliation and dispersion of O‐g‐C3N4 were strongly enhanced compared to pristine g‐C3N4 due to rich hydrophilic carboxyl and hydroxyl groups. The amount of ROS generated by O‐g‐C3N4 was about 13.8% more than that of g‐C3N4. Then, the polyvinyl alcohol (PVA)/chitosan (CS)/O‐g‐C3N4 (PCO) composite nanofiber membranes were prepared by electrospinning. The contact angle of the PCO nanofiber membranes decreased from 55.0° ± 0.5 to 45.9° ± 0.2 along with the increased amount of O‐g‐C3N4, indicating the improvement of hydrophilicity. Meanwhile, the diameter of nanofibers increased from 148.0 ± 22.9 nm to 244.0 ± 52.3 nm with the loading ratio from 0% to 17%. The PCO nanofiber membranes exhibited significantly higher antibacterial activity compared to the blank nanofiber membranes and bare O‐g‐C3N4. The maximum diameter of the inhibition zone against Escherichia coli and Staphylococcus aureus could reach 26 ± 0.1 mm and 16 ± 0.2 mm, respectively. The inhibition rate against E. coli could reach 97% in 24 h under the irradiation of simulated sunlight. Based on reactive oxygen species (ROS) testing, zeta potential, and bacterial inhibition experiments, a possible synergistic mechanism was proposed. The electrostatic adsorption effect of PCO nanofiber membranes and ROS could effectively decompose the organic components of bacteria and destroy their structural integrity. The results indicated that the antibacterial PCO composite nanofiber membranes have wide application prospects in biomedical‐related fields.

Pushing the Operational Barriers for g-C3N4: A Comprehensive Review of Cutting-Edge Immobilization Strategies

“…In addition, several composites were synthesized by a combination of chitosan and PVA [61]. In this context, oxygenated g-C 3 N 4 nanosheets were immobilized into a solution of PVA/chitosan by electrospinning technology, which will be explained in Section 3.2, to fabricate nanofiber membranes [62]. The immobilization of g-C 3 N 4 by this method permits its application in other uses such as food packaging [61] or antibacterial activity [62].…”

“…In this context, oxygenated g-C 3 N 4 nanosheets were immobilized into a solution of PVA/chitosan by electrospinning technology, which will be explained in Section 3.2, to fabricate nanofiber membranes [62]. The immobilization of g-C 3 N 4 by this method permits its application in other uses such as food packaging [61] or antibacterial activity [62]. Table 2 summarizes several examples of g-C 3 N 4 immobilization, highlighting uses different to the degradation of pollutants.…”

“…Chitosan and PVA Encapsulation Preparation of film for food packaging [61] Chitosan and PVA Electrospinning Nanofiber membranes with light catalytic antibacterial activity [62] Natural latex foam Brush coating PVA/MXene and protonated-g-C 3 N 4 . Solar steam generation.…”

“…In the past year, numerous studies have sought to modify fibers using non-metal components for antibacterial performance. Examples of this trend and application to immobilize g-C 3 N 4 are the studies of Luan et al [46] and Bai et al [62]. In the research of Luan et al [46], polydopamine (PDA) has been added to improve the dispersion of g-C 3 N 4 nanosheets in the PVA polymer solution, providing an enhancement in photocatalytic bacterial inhibition activity.…”

“…Bai et al [62] used a PVA fiber with chitosan and modified g-C 3 N 4 , specifically oxygenated and termed O-g-C 3 N 4 with 12% O 2 content. In contrast to the study of Luan et al [46], using a fiber containing 17% O-g-C 3 N 4 detected a higher inhibition effect on Escherichia coli and Staphylococcus aureus with inhibition zone diameters of 26 mm and 16 mm, respectively.…”