Development of Photoactive g-C₃N₄/Poly(vinyl alcohol) Composite Hydrogel Films with Antimicrobial and Antibiofilm Activity

Abstract

Free-standing, composite hydrogels containing the visible-light responsive metal-free semiconductor graphitic carbon nitride (g-C 3 N 4 ) as an integral component have been fabricated by direct casting techniques. At 0.67% g-C 3 N 4 loading, intermolecular interactions between the semiconductor particles and the PVA polymer chains enhance both the mechanical and photophysical properties of the resulting hydrogels. In contrast, much higher g-C 3 N 4 loadings of 3.3 or 6.7% g-C 3 N 4 resulted in growth of the average semiconductor particle size and reduction in interactions between the incorporated photocatalyst and the PVA chains. The increased dimensions of the g-C 3 N 4 semiconductor particles had the effect of compromising the mechanical properties of the composite system and reducing the lifetime of photogenerated charge carriers. However, the close proximity of g-C 3 N 4 particles that is realized at increased semiconductor loading densities improves the absorption cross section of the material, resulting in an overall improvement in the photocatalytic activity of the material. Application of visible radiation caused all of the composite hydrogels to generate hydrogen peroxide (H 2 O 2 ) at catalytic rates of 0.9−2.5 μM/min, while H 2 O 2 decomposition rates remained similar across the different preparations. In studies to examine antimicrobial performance, irradiation of 6.7% g-C 3 N 4 /PVA hydrogel samples with visible radiation (400 ≤ λ ≤ 800 nm) generated sufficient H 2 O 2 to significantly reduce both the viable planktonic cell population and biofilm formation in cultures of Pseudomonas aeruginosa. KEYWORDS: g-C 3 N 4 , hydrogel, H 2 O 2 , antibiofilm, antibacterial

Fabrication and Performance of a Multidischarge Cold-Atmospheric Pressure Plasma Array

“…However, the peroxide concentration in the biological test samples in our study was not determined directly. In addition, the detection of H 2 O 2 suggests one potential plasma mechanism responsible for the observed loss of viable CFU since peroxides are known to exert antimicrobial effects [21], [22], and these effects can be further enhanced by the plasma treatment [23]. This preliminary work demonstrates that our device has the capacity to create hydrogen peroxide, but it is probable that the antimicrobial activity that we observe in our experiments is due to a combination of plasma-generated species.…”

“…Indeed, it would need to be higher to exert an antimicrobial effect of the magnitude that we see in these experiments. Other studies support that peroxide concentrations from 150 μM [21] to 0.88 M [22], [23] were required to produce measurable and comparable antimicrobial effects. However, the peroxide concentration in the biological test samples in our study was not determined directly.…”

Photoinduced post-modification of graphitic carbon nitride-embedded hydrogels: synthesis of 'hydrophobic hydrogels' and pore substructuring

“…Integration of g-CN into hydrogels has been popularized in the last four years, where g-CN nanosheets can be implemented into hydrogels through embedding [ 36 ] or covalent binding [ 37 – 38 ] for the target application such as reinforced hydrogels [ 39 ] and hydrogels for photoredox-based applications [ 40 – 41 ].…”

1,4,5,8-Naphthalene tetracarboxylate dianhydride/g-C3N4 van der Waals heterojunctions exhibit enhanced photochemical H2O2 production and antimicrobial activity

“…11,12 Subsequent studies, conducted by both our group and others, have illustrated that CN-mediated ROS formation reduces microbial biolm formation, but complete inhibition was generally not observed. 13,14 It is clear that efficient photochemical formation of ROS is critical for developing CN-based systems that effectively combat microbial biolms. Unfortunately, the photochemical activity of CN can be compromised by high charge carrier recombination rates.…”

“… 11,12 Subsequent studies, conducted by both our group and others, have illustrated that CN-mediated ROS formation reduces microbial biofilm formation, but complete inhibition was generally not observed. 13,14 …”