Photocatalytic Antibacterial Activity Research Articles

Recent Advances in Antibacterial Strategies Based on TiO2 Biomimetic Micro/Nano-Structured Surfaces Fabricated Using the Hydrothermal Method

Ti and its alloys, widely utilized in orthopedic and dental implants, inherently lack antibacterial properties, posing significant infection risks, especially in the context of growing antibiotic resistance. This review critically evaluates non-antibiotic antibacterial strategies, with a particular focus on surface modifications and micro/nano-structured surfaces. Micro/nano-structured surfaces, inspired by natural topographies, utilize physical mechanisms to eradicate bacteria. Despite their potential, the antibacterial efficacy of these surfaces remains insufficient for clinical application. Titanium dioxide (TiO2), known for its excellent photocatalytic antibacterial activity and biocompatibility, is emerging as an ideal candidate for enhancing micro/nano-structured surfaces. By combining the photocatalytic antibacterial effects of TiO2 with the mechanical bactericidal properties of micro/nano-structured surfaces, superior antibacterial performance can be achieved. The hydrothermal method is frequently employed to fabricate TiO2 micro/nano-structured surfaces, and this area of research continues to thrive, particularly in the development of antibacterial strategies. With demonstrated efficacy, combined antibacterial strategies based on TiO2 micro/nano-structured surfaces have become a prominent focus in current research. Consequently, the integration of physical stimulation and chemical release mechanisms may represent the future direction for TiO2 micro/nano-structured surfaces. This review aims to advance the study of TiO2 micro/nano-structured surfaces in antibacterial applications and to inspire more effective non-antibiotic antibacterial solutions.

Fabrication of sulfur doped exfoliated gCN photocatalyst for enhanced visible light degradation of pernicious organic pollutants and their photocatalytic antibacterial activity

The synthesis of sulfur-doped exfoliated graphitic carbon nitride (S-gCN) photocatalyst was achieved by the implementation of a two-step calcination technique. The XRD results revealed that all the fabricated photocatalytic materials were crystalline in nature. The inclusion of 5% sulfur in gCN led to a conspicuous escalation in the surface area of photocatalyst, rising from 10.294 to 61.185 m2g⁻1. Morphological scrutiny of the samples using FE-SEM revealed that pristine gCN exhibited tightly stacked small nanosheets, whereas inclusion of sulfur and exfoliation resulted in generation of loosely distributed large nanosheet. Furthermore, the inclusion of sulfur also induced a shift in the energy band gap (Eg) from 2.81 eV to 2.63 eV, making it felicitous for investigation as proficient visible light photocatalyst. Additionally, the photoluminescence photo-induced charge carrier recombination behavior revealed a reduced peak intensity for 5% S-gCN compared to other synthesized compositions. This observation can be directly linked to the minimized electron-hole pairs recombination during photocatalysis, underscoring its superior photocatalytic performance. Our findings revealed that the 5% S-gCN photocatalyst exhibit the most promising attributes, it degraded Tetracycline drug, Chlorpyrifos pesticide and Eriochrome Black T dye under visible light irradiation almost ∼4 times more efficiently than pristine gCN. Additionally, exceptional visible light photocatalytic antibacterial efficacy was also perceived by 5% S-gCN against S. aureus bacteria. Overall, the present research sheds light on how doping and exfoliation interact to modify the structure and catalytic properties of gCN, paving the way for the development of outstanding performance, visible light-responsive efficient photocatalysts for environmental restoration.

CuO/ZnO heterojunction nanofilm for effective photocatalytic disinfection

Pathogenic bacteria can spread rapidly from contaminated surfaces to human skin once humans touch such surfaces, resulting in contact infection and subsequent bacterial infectious diseases. In addition to the bacterial drug resistance induced by overuse of antibiotics, the commonly used antibiotic bacteria-killing strategy is unsuitable for surface sterilization of facilities. Herein, a heterojunction CuO/ZnO nanofilm was constructed on glass plates by calcination and atomic layer deposition. This film exhibited excellent photocatalytic antibacterial activity under visible light. The heterostructure between CuO and ZnO at the interface accelerated the separation of photogenerated electrons and holes, resulting in increased yield of reactive oxygen species, which effectively kill bacteria. After 5 min of simulated sunlight irradiation, the antibacterial efficiencies of CuO/ZnO against Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) were 99.68 ± 0.31 % and 96.49 ± 0.78 %, respectively. The photocatalytic antimicrobial nanofilm synthesized in this study can potentially be used for rapid and safe disinfection of contact surfaces in public facilities.

Development of superhydrophilic ZnOX/TiO2 with visible light-induced self-cleaning and antibacterial properties

Many studies aimed to improve the antibacterial ability and applicability of antibacterial surface materials by altering their chemical composition and structure. In this study, we successfully prepared a multifunctional ZnOX/TiO2 (0<X ≤ 2) nanocomposites by a sol-gel method, which exhibits visible light responsive self-cleaning, antibacterial adhesion, and antimicrobial properties. In the comparison of the three zinc sources, it was found that the ZnOX/TiO2 prepared with zinc sulfate doping had a water contact angle of only 1.7°, with enhanced hydrophilicity, and exhibited the best photocatalytic activity under visible light, with a removal rate of up to 90.2% of methylene orange (MO). Antibacterial tests revealed the average diameters of the inhibition halos for Escherichia coli and Staphylococcus aureus were 10 and 12 mm, respectively, thereby showing excellent antibacterial activity under visible light. The low photogenerated electron-hole recombination and the high rates of ·OH and ·O2- generation through photo-induced interface charge transfer in ZnOX/TiO2 composite, which is the main reason for enhancing the photocatalytic antibacterial activity under visible light irradiation. Release of Zn2+ species, resulting in significant antibacterial performance even under dark conditions. This study combines doping and surface modification, introduce abundant surface hydroxyl groups to endow the composite material surface with superhydrophilicity, anti-bacterial adhesion, and antibacterial properties that can meet the needs of clean and antibacterial surfaces in medical.

Eco-friendly activation of cotton textiles with LiNbO3 nanoparticles for enhanced self-cleaning and antibacterial performance

Cotton textiles play a universal role in everyday life, but they are prone to stain and serve as a primary channel for transmitting viruses and bacteria. The photocatalytic/antibacterial coatings are highly effective in addressing bacterial contamination on fabrics, although their efficacy diminishes with continuous use and washing. Here, insights are provided into the attachment of LiNbO3 on cotton surfaces using eco-friendly chemical activators to promote resistance to washing cycles, self-cleaning, and bactericide textiles. LiNbO3 nanoparticles were synthesized by low-temperature hydrothermal synthesis and directly applied to cotton fabric using immersion. The synthesized nanoparticles were characterized by X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET) N2 adsorption, diffuse reflectance for band gap determination, and Raman spectroscopy. A simple and effective impregnation method was used, promoting an ester-bond attachment between the cotton surface and the activators. Microscopy analysis (SEM) confirmed the successful deposition of the nanoparticles on cotton fabric. The LiNbO3 coating consisted of transparent layers and did not change the properties of cotton. Methylene blue stains are generally eliminated under UV light after 2 h using nanoparticles and activators. Antibacterial properties were evaluated under visible light through direct contact with bacterial suspensions and culturing. The coated cotton fabric that was activated with oxalic acid exhibited significant photocatalytic antibacterial activity against both Escherichia coli (gram-negative) and Staphylococcus aureus (gram-positive) bacteria, with bacterial reduction rate above 97 %, even after 10 washing cycles. This performance can be attributed to the effective coupling of LiNbO3 with oxalic acid in the cotton’s surface and its resistance to washing out. This study's novel synthesis and coating method offers an environmentally friendly, cost-effective, and straightforward approach for producing LiNbO3 self-cleaning and antibacterial surface-activated cotton.

Multiple strategy for antibacterial effect via copper porphyrin doping polyphenolic aldehydes based covalent organic framework

Microbial infections continue to be one of the cosmopolitan safety hazards to humankind. To achieve effective sterilization, it is urgent to develop non-antibiotic strategies or integrating multiple antimicrobial methods. Organic photo-antimicrobials (OPAMs) has attracted attention in fighting against bacteria by reactive oxygen species (ROS) or heat without triggering drug resistance. In our work, a copper-porphyrin doping donor-acceptor (D-A) type covalent organic framework (COF), named CTF-BTA2OH-Por(Cu), is constructed to achieve synergistic antibacterial effects by ROS generation and protein degradation. Copper-porphyrin doping improves ROS generation of D-A COF, showing great photocatalytic antibacterial activity (>90 % within 1 h). Additionally, the polyphenolic aldehydes of BTA2OH can interact with protein strongly and cause degradation, resulting inhibition of bacteria growth without light. Thus, CTF-BTA2OH-Por(Cu) showed antibacterial activity under both light and dark conditions. These findings give inspiration for COF multifunctional design for antimicrobials strategy and its application in supplies anti-infection or preservation.

Defect regulation of p-n scheme Cu2NxO1–x/PDINH composites for enhanced photocatalytic antibacterial activities

The defect regulation and p-n heterojunction of composites have gained significant attention due to their potential applications. Nitrogen (N) as doping heteroatoms and perylene-3,4,9,10-tetracarboximide (PDINH) as an appropriate n-type semiconductor were innovatively and reasonably selected to enhance the photocatalytic performance of pristine p-type cuprous oxide (Cu2O). In this study, the defect regulation of N doping (1) achieved the small-size effect of Cu2O, (2) optimized the electron features, and (3) improved the kinetics of reactive oxygen species. The p-n heterojunction with PDINH was developed to sharply improve the light utilization of Cu2O, from the UV region to the near-infrared region. As expected, the optimized Cu2NxO1–x/PDINH (x = 0.02) exhibited excellent long-term photocatalytic antibacterial activities, with antibacterial rates exceeding 91 % against Staphylococcus aureus and Pseudomonas aeruginosa. Defect regulation and p-n heterojunction of Cu2O-based composites thus provide a great deal of potential for future advancements in photocatalysis.

Thermal treatment impact on the evolution of active phases in layered double hydroxide-based ZnCr photocatalysts: Photodegradation and antibacterial performance

Abstract This study investigated the influence of thermal treatment on the photocatalytic performance of ZnCr layered double hydroxide-based mixed metal oxides in the degradation of methylene blue and brilliant cresyl blue organic dyes under simulated solar light irradiation. The photocatalysts were synthesized using a simple coprecipitation method and subjected to thermal treatment at temperatures ranging from 100°C to 900°C. Additionally, the study explored the antibacterial activity against Escherichia coli and Staphylococcus aureus using a novel antibacterial experimental setup. It not only involved the introduction of ZnCr samples into BioPeptone/prepared cell suspension to enhance photocatalyst–bacteria cell contact but also included research on antibacterial activity induced by solar irradiation and also in the absence of light, providing crucial insights into photocatalytic antibacterial activity of ZnCr photocatalysts. Despite satisfactory efficiencies observed for all thermally treated ZnCr samples (removal efficiency ranging from 40% to 90%), ZnCr 900 (thermally treated at 900°C) exhibited exceptional performance, achieving nearly 100% removal efficiency and complete growth inhibition for both bacteria. Integrating these findings with structural and textural characterization data, as well as kinetic studies, our comprehensive analysis enhances the understanding of structure-dependent photocatalytic activities. These insights open possibilities for the application of ZnCr photocatalysts in water purification and environmental remediation.

Construction of atom co-sharing Bi/Bi4O5Br2 nanosheet heterojunction for plasmonic-enhanced visible-light-driven photocatalytic antibacterial activity

The rapid advancement of photodynamic therapy (PDT) antibacterial materials has led to promising alternatives to antibiotics for treating bacterial infections. However, antibacterial drugs have poor light absorption and utilization rates, which limits their practical application. Constructing two-dimensional (2D) heterojunctions from materials with matching photophysical properties has emerged as a highly effective strategy for achieving high-efficiency photo-antibacterial performance. Here, we designed and prepared an atom co-sharing Bi/Bi4O5Br2 nanosheet heterojunction by a simple in situ reduction. This heterojunction material combines outstanding biocompatibility with excellent bactericidal efficiency, which exceeded 90 % against Escherichia coli (a Gram-negative bacterium) and Staphylococcus aureus (a Gram-positive bacterium) under visible light irradiation, around nine-fold higher than that with pure Bi4O5Br2 nanosheets. The results suggest that localized surface plasmon resonance (LSPR) of shared Bi atoms on the Bi4O5Br2 nanosheets promotes light utilization and the separation and transfer of photo-generated charges, thus producing more abundant reactive oxygen species (ROS), which can partake in the PDT antibacterial effect. Our study underscores the potential utility of LSPR-enhanced Bi-based nanosheet heterojunctions for safe and efficient PDT to combat bacterial infections.

Highly flexible carbon nitride-polyethylene glycol-cellulose acetate film with photocatalytic antibacterial activity for fruit preservation

Cellulose acetate film, as a biodegradable and biomass-derived material, has great potential applications in food packaging. However, the poor mechanical and antibacterial properties limit its applications. Herein, a highly flexible carbon nitride-polyethylene glycol-cellulose acetate (CN-PEG-CA) film was successfully prepared by combining graphitic carbon nitride (g-C3N4) photocatalyst with cellulose acetate (CA). The g-C3N4 enables the film with antibacterial activity, as a green photocatalyst. PEG softens the rigid polymer CA and crosslinks CA, PEG, and g-C3N4 together by hydrogen bonding, as a flexible crosslinker. X-ray diffractometer (XRD), scanning electron microscope (SEM), and Fourier transform infrared spectrum (FT-IR) characterizations confirmed the successful preparation of the CN-PEG-CA film. The mechanical property tests demonstrated that adding PEG increased the elongation at break of the film by about 4 times. The composite film had high antibacterial activity, and the bactericidal rates on Escherichia coli and Staphylococcus aureus were 99.98 % and 99.89 %, respectively. It effectively extended the shelf life of strawberries to 96 h and effectively maintained the quality of strawberries during storage. After 96 h, the weight loss rate of strawberries packaged with 15 % CN-PEG-CA film was 21.83 %, vitamin C content was 45.47 %, titratable acidity content was 0.89 %, and color, hardness and total soluble solids were well maintained. And biocompatibility test results showed that the film was safe and nontoxic. From the ecological and economic point of view, the highly flexible and biodegradable films with efficient photocatalytic antibacterial activity synthesized in this paper have great potential in the field of food packaging.

Defect engineering of Cu2-xGaxO/PDINH nanomaterial for significantly improved photocatalytic antibacterial activities

The judicious engineering of defects and microstructure in novel photocatalysts is essential for optimizing their functional properties. This study focuses on the design of copper oxide (Cu2O)-based catalysts employing defect engineering and heterogeneous composition with perylene-3,4,9,10-tetracarboximide (PDINH) to enhance their photocatalytic antibacterial performance. Introducing transition metals such as gallium (Ga) into the Cu2O lattice serves to 1) generate Cu vacancies to accelerate reactive oxygen species (ROS) kinetics, 2) induce a small size effect in Cu2O nanoparticles to amplify photocatalytic activities, and 3) fine-tune electronic characteristics by modulating the electron density near the Fermi level and the d-band center. The defect engineering of doped Ga atoms and the p-n junction construction with PDINH resulted in a notable redshift of the light absorption edge of Cu2O. The optimized Cu2-xGaxO/PDINH (x=0.2) nanomaterials displayed superior photocatalytic antibacterial performance, achieving bacterial inhibition rates greater than 91% against Staphylococcus aureus and Pseudomonas aeruginosa. The nanomaterial also exhibited a large double-layer capacitance, elevated photocurrent density, and substantial ROS production. Cu1.8Ga0.2O/PDINH nanomaterial was a potent candidate for photocatalysis and environmentally friendly antibacterial treatments.

Photocatalytic Zinc Oxide Nanoparticles in Antibacterial Ultrafiltration Membranes for Biofouling Control.

Global water scarcity is a threat that can be alleviated through membrane filtration technologies. However, the widespread adoption of membranes faces significant challenges, primarily due to membrane biofouling. This is the reason why membrane modifications have been under increasing investigation to address the fouling issues. Antibacterial membranes, designed to combat biofouling by eliminating microorganisms, offer a promising solution. Within this study, flat sheet ultrafiltration (UF) membranes with integrated photocatalytic zinc oxide (ZnO) nanoparticles were developed, characterized, and assessed through filtration and fouling tests. The antibacterial properties of the membranes were conducted in static tests using Gram-negative bacteria-Escherichia coli-and natural tap water biofilm. The results demonstrated a notable enhancement in membrane surface wettability and fouling resistance. Furthermore, the incorporation of ZnO resulted in substantial photocatalytic antibacterial activity, inactivating over 99.9% of cultivable E. coli. The antibacterial activity persisted even in the absence of light. At the same time, the persistence of natural tap water organisms in biofilms of modified membranes necessitates further in-depth research on complex biofilm interactions with such membranes.

Nickel-doped microtubular CeVO4 inspired by wood powder structure for visible light photocatalytic degradation of methylene blue and bacterial inactivation

In this study, inspired by natural wood powder structure, nickel-doped microtubular cerium vanadate (Ni/T-CeVO4) was obtained using wood powder as a biological template. Photocatalytic experiments under visible light revealed that Ni/T-CeVO4-3wt possessed the highest photocatalytic activity, with a degradation efficiency of up to 99 % for methylene blue. The enhanced photocatalytic performance was not only attributed to the microtubule wood powder structure assigned the composite a larger specific surface area but also the nickel doping narrowed the band gap of the composites while introducing more oxygen vacancies. The rapidly generated current in transient photocurrent responses and small arc radius in electrochemical impedance spectra further indicated the higher photogenerated carrier separation and smaller photogenerated electron transfer resistance within the composite. ESR spin-trapping tests proved that O2− and OH dominated the photocatalytic process. Furthermore, owing to its unique structural characteristics, the composite showed excellent photocatalytic antibacterial activity against Staphylococcus aureus and Escherichia coli. The present study provides a theoretical basis for developing efficient dual-effect photocatalysts using visible light to remove organic dyes and pathogenic bacteria from the water environment.

Construction of a g-C3N4/Bi(OH)3 Heterojunction for the Enhancement of Visible Light Photocatalytic Antibacterial Activity.

Photocatalytic technology has been recently conducted to remove microbial contamination due to its unique features of nontoxic by-products, low cost, negligible microbial resistance and broad-spectrum elimination capacity. Herein, a novel two dimensional (2D) g-C3N4/Bi(OH)3 (CNB) heterojunction was fabricated byincorporating Bi(OH)3 (BOH) nanoparticles with g-C3N4 (CN) nanosheets. This CNB heterojunction exhibited high photocatalytic antibacterial efficiency (99.3%) against Escherichia coli (E. coli) under visible light irradiation, which was 4.3 and 3.4 times that of BOH (23.0%) and CN (28.0%), respectively. The increase in specific surface area, ultra-thin layered structure, construction of a heterojunction and enhancement of visible light absorption were conducive to facilitating the separation and transfer of photoinduced charge carriers. Live/dead cell staining, sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) assays and scanning electron microscopy (SEM) have been implemented to investigate the damage to the cell membrane and the leakage of the intracellular protein in the photocatalytic antibacterial process. The e-, h+ and O2•- were the active species involved in this process. This study proposed an appropriate photocatalyst for efficient treatment of bacterial contamination.

Enhanced photocatalytic antibacterial activity of Au-coated Ni–Ti–O nanotubes for biomedical applications

Nickel-titanium (NiTi) alloy is a smart material exhibiting superelasticity, contributing to low stiffness and facilitating integration with bone structures. However, NiTi alloy's bioactivity and antibacterial activity limit its dental applications. In this study, we fabricated nickel titanium oxide (Ni–Ti–O) nanotubes with the potential for bioactivity and photocatalytic properties on the surface of NiTi alloy. Specifically, we applied a coating of gold (Au) nanoparticles to the surface of Ni–Ti–O nanotubes, in order to leverage the antibacterial activity through the photocatalytic effect under 470 nm visible light. Field-emission scanning electron microscopy (FE-SEM) and high-resolution transmission electron microscopy (HR-TEM) observations revealed that Au was deposited mainly at the top surface of Ni–Ti–O nanotubes (diameter: 12.76 ± 2.91 nm, height: 721.12 ± 50.25 nm). X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and diffuse reflectance spectroscopy (DRS) analyses revealed that the Ni–Ti–O nanotubes were NiTiO3 crystalline phases with low crystallinity. Therefore, based on the methylene blue (MB) degradation test, the photocatalytic effect was only achieved under visible light at 470 nm, facilitated by the presence of Au. The antibacterial colony forming unit test and enzymatic activity tests demonstrated that Au-coated Ni–Ti–O nanotubes displayed excellent antibacterial activity under 470 nm visible light irradiation, which was also attributed to photocatalytic effect. Consequently, the combination of Au-coated Ni–Ti–O nanotubes and visible light-based photofunctionalization holds promise for expressing antibacterial properties in dental applications.

Designing a photocatalytic and self-renewed g-C3N4 nanosheet/poly-Schiff base composite coating towards long-term biofouling resistance.

Inhibiting the adhesion and growth of marine microorganisms through photocatalysis is a potentially efficient and environmentally friendly antifouling strategy. However, the undesired "shading effect" caused by resin coatings and microbial deposition reduces the utilization of the catalysts and leads to a failure in the antifouling active substance on the coating surface. Here, we successfully developed a composite coating (DPC-x) combining g-C3N4 nanosheet (g-C-NS) photocatalysts with degradable green poly-Schiff base resins, which integrates the dual functions of enhanced dynamic self-renewal and photocatalytic antibacterial activities towards long-term anti-biofouling. The controllable and complete degradability of the poly-Schiff base polymer chains and the self-renewal mechanism of the DPC-x coating exposed the internal g-C-NS, which provided a constant stream of photocatalytic reactive interfaces for 100% utilization and release of the photocatalysts. g-C-NS were homogeneously dispersed in the degradable resin coating, significantly enhancing and adjusting the self-renewal rate of the poly-Schiff base resin coating in visible light. The degradation reaction rate of DPC-0.2 (20 wt% g-C-NS) was 40 times that of DPC, thus improving the capabilities of surface self-renewal and fouling-release. Due to the synergistic antifouling mechanism of the efficient antibacterial properties and the enhanced degradation/self-renewal, the antimicrobial rates of DPC and DPC-0.2 were 94.58% and 99.31% in the dark, and 98.2% and 99.87% in visible light. DPC-x has excellent all-weather antimicrobial efficacy and could offer a new perspective on eco-friendly marine antifouling strategies.

AgNPs/g-C3N4/PVA antibacterial hydrogel with excellent photocatalytic antibacterial activity for wound dressing

AgNPs/g-C3N4/PVA hydrogel has been prepared by cyclic freeze-thaw method. E. coli was used as the model microbe and full-thickness wound defect models in mice were established to assess the antimicrobial activity of the hydrogel in vitro and in vivo.

Highly hydrophilic and dispersed TiO2 nano-system with enhanced photocatalytic antibacterial activities and accelerated tissue regeneration under visible light

Titanium dioxide (TiO2)-based photodynamic antibacterial (PDA) agents present a novel approach for addressing drug-resistant bacterial infections and the associated tissue damage. However, the suboptimal dispersibility, negative charge, and weak photocatalytic activity under visible light of TiO2 hinder its practical applications. This study aimed to address these limitations by developing a highly hydrophilic and dispersed Zn-TiO2/reduced graphene oxide (rGO) (HTGZ) nano-system with exceptional visible light catalytic activity and tissue repair ability. HTGZ produced an antibacterial ratio over 98% within a short time, likely due to the enhanced production of reactive oxygen species under visible light. After being co-cultured for 4 days, L929 cells and BMSCs maintained over 90% activity, indicating that HTGZ had no significant cytotoxicity. Furthermore, the transcriptomic and metabolic analyses revealed that the antibacterial mechanism mainly came from the destruction of cell membranes and the disruption of various metabolic processes, such as purine metabolism and fatty acid biosynthesis. Critically, results of in vivo experiments had authenticated that HTGZ significantly promoted infected tissue regeneration by slaughtering bacteria and release Zn2+. After 14 days, the wound area was only one-third that of the control group. Overall, the enhanced antibacterial efficacy and wound-healing potential position HTGZ as a promising nano-antibacterial medication for the clinical treatment of infectious bacterial diseases.

Visible-light-driven Au/PCN-224/Cu(II) modified fabric with enhanced photocatalytic antibacterial and degradation activity and mechanism insight

The development of novel photocatalytic platform for efficient water purification and sterilization is of utmost importance due to the significant threat of chronic diseases resulting from water pollution and bacterial contamination. Herein, a high-efficiency, easy-recyclable, and environment-friendly photocatalytic fabric was developed as a water disinfection and organic pollutant degradation platform. In which, microamounts of Au nanoparticles (2 wt%) and Cu(II) clusters (2.5 wt%) co-decorated porphyrinic MOF (Au/PCN-224/Cu(II)) coating was applied as photocatalytic surface, and flexible cotton fabric served as stable support. Au/PCN-224/Cu(II) composite photocatalyst was prepared via a facile photo-deposition procedure followed by impregnation method, and further immobilized onto polydopamine (PDA) pre-treated cotton fabric through catechol-amine reaction. The fabricated photocatalytic platform exhibited excellent ability to generate reactive oxygen species (ROS) by multiple routes under low-power visible light irradiation, and achieved efficient photodisinfection effects for causative organism including Gram-negative Escherichia coli (E. coli) and Gram-positive Staphylococcus aureus (S. aureus) without the obvious leakage of metal ions from the potocatalyst during the reaction. Additionally, the reaction rate constant for organic dye MB photodegradation achieved by Au/PCN-224/Cu(II)@Fabric was 3.73 times higher than that of PCN-224@Fabric, and the degradation intermediates analysis was also conducted. The band alignments of PCN-224, Au/PCN-224, Au/PCN-224/Cu(II) photocatalysts were determined, and the charge transfer mechanism within Au/PCN-224/Cu(II) photocatalyst was elucidated through the utilization of DRS, Mott − Schottky, ESR, EIS, and photocurrent analyses. It is suggested that the deposition of Au and doping of Cu(II) both with small amounts enhanced the light absorption capacity, and also improved the charge separation ability through the surface plasmon resonance (SPR) effect and interfacial electron transfer (IFCT) mechanism. Moreover, Au SPR and Cu doping exhibited a substantial enhancement in photothermal conversion effect, thereby synergistically reinforcing the sterilization performance. This work provides an approach for the development of effective photocatalytic platform based on porphyrinic MOFs combined with trace metal co-catalysts in the application of water disinfection and purification.

Photo-crosslinked composite hydrogels with silver-deposited polymeric carbon nitride for boosting antibacterial activity

Rational design of antibacterial hydrogels is an important link to promote the multi-scenario application of this promising soft material. Herein, acrylamide and sodium alginate were selected as mixed monomers, silver-deposited polymeric carbon nitride nanosheets were used as a photoinitiator, pre-gelation was achieved under UV irradiation, and then a composite hydrogel was obtained through calcium ion crosslinking. The composite hydrogels exhibit good mechanical stability, structural stability in water and degradability under simulated physiological conditions. The composite hydrogels have the activity of killing Escherichia coli with or without light. The visible light response and surface plasmon resonance effect of the silver-deposited polymeric carbon nitride boosted the photocatalytic antibacterial activity of the composite hydrogels, and the bactericidal rate of the optimal sample reached 95.5% after 120 min of visible light irradiation. This work provides a constructive and green roadmap for the design of composite dual-network photoresponsive antibacterial hydrogels.