Photocatalytic Bacterial Inactivation by a Rape Pollen-MoS₂ Biohybrid Catalyst: Synergetic Effects and Inactivation Mechanisms

Abstract

A novel and efficient 3D biohybrid photocatalyst, defective MoS2 nanosheets encapsulated carbonized rape pollen, was fabricated and applied to water disinfection. The rape pollen-MoS2 (PM) biohybrid showed excellent dispersibility, high stability, and efficient charge-carrier separation and migration ability, resulting in the highly enhanced photocatalytic inactivation performance toward various waterborne bacteria under different light sources. The inactivation mechanisms were systematically investigated. Reactive species (RSs), including electrons, holes, and reactive oxygen species (•O2 – and •OH), played major roles in inactivating bacteria. The antioxidant system of bacteria exhibited a self-protection capacity by eliminating the photogenerated RSs from PM biohybrid at the early stage of inactivation. With the accumulation of RSs, the cell membrane and membrane-associated functions were destroyed, as suggested by the collapse of cell envelope and subsequent loss of cell respiration and ATP synthesis capacity. The microscopic images further confirmed the destruction of the bacterial membrane. After losing the membrane barrier, the oxidation of cytoplasmic proteins and lipids caused by invaded RSs occurred readily. Finally, the leakage of DNA and RNA announced the irreversible death of bacteria. These results indicated that the bacterial inactivation began with the membrane rupture, followed by the oxidation and leakage of intracellular substances. This work not only provided a new insight into the combination of semiconductors with earth-abundant biomaterials for fabricating high-performance photocatalysts, but also revealed the underlying mechanisms of photocatalytic bacterial inactivation in depth.

Interfacing Iodine‐Doped Hydrothermally Carbonized Carbon with Escherichia coli through an “Add‐on” Mode for Enhanced Light‐Driven Hydrogen Production

“…Cells with intact membrane emit green fluorescence, and those with damaged cell membranes emitted red signals. [51] The consistent green fluorescence signals gave rise by the E. coli cells before and after reactions suggested they were in a healthy state throughout the H 2 production process. All of the above-mentioned evidence illustrated that both the fabrication and reaction processes were biocompatible to bacterial cells, which ensured its potentials for practical applications.…”

“…As presented in Figure 5a, the cell viability remained almost unchanged during the entire reaction period, indicating that both the light intensity and the I-HTCC NPs did not affect cell growth. The bacterial membrane consists of phospholipid bilayers, [51] thus the peroxidation intermediate MDA was measured to reflect the levels of membrane oxidation. The MDA concentration was stable state in the first 120 min, followed by a slight increase in the last 60 min.…”

Inside‐and‐Out Semiconductor Engineering for CO2 Photoreduction: From Recent Advances to New Trends

“…[ 152,153 ] In Z‐scheme junction, the photogenerated charge carriers are efficiently separated through the interface between semiconductor and semiconductor or semiconductor–metal–semiconductor, and meanwhile the strong oxidative and reductive potentials were maintained. [ 154–157 ] 5) A series of new photocatalytic systems are developed for CO 2 photoreduction, such as metal organic frameworks (MOFs), [ 158–163 ] covalent organic frameworks (COFs), [ 164–169 ] semiconductor biohybrids systems, [ 170–172 ] and single atom. [ 173–177 ] These systems have different chemical affinities to CO 2 molecules, and thus may change the redox reaction pathways during CO 2 reduction process.…”

Solar‐Driven Photocatalytic Disinfection Over 2D Semiconductors: The Generation and Effects of Reactive Oxygen Species

“…Carbonized rape pollen skeleton, originating from plants, showed a 3D porous structure which provided platforms for secondary component loading and plenty of active sites ( Figure a). [ 96 ] The coupling of defective MoS 2 with ripe pollen formed a band alignment that was suitable for ⋅O 2 − generation (Figure 5b, c). As the leading bactericidal element, ⋅O 2 − contributed to the accelerated visible light‐driven photocatalysis with 7 log E. coli , S. aureus and P. aeruginosa completely inactivated within 60 min.…”