Rapid and Highly Effective Noninvasive Disinfection by Hybrid Ag/CS@MnO2 Nanosheets Using Near-Infrared Light

Effective killing of bacteria under blue-light irradiation promoted by green synthesized silver nanoparticles loaded on reduced graphene oxide sheets

Graphene oxide (GO) materials loaded with silver nanoparticles (AgNPs) have drawn considerable attention due to their capacity to efficiently inactivate bacteria though a multifaceted mechanism of action, as well as for presenting a synergetic effect against bacteria when compared to the activity of AgNPs and GO alone. In this investigation, we present an inexpensive and environmentally-friendly method for synthesizing reduced GO sheets coated with silver nanoparticles (AgNPs/r-GO) using a coffee extract solution as a green reducing agent. The physical and chemical properties of the produced materials were extensively characterized by scanning electron microscopy (SEM), field-emission gun transmission electron microscopy (FEG-TEM), ultraviolet and visible absorption (UV-Vis), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), inductively coupled plasma-optical emission spectroscopy (ICP-OES) and ion release determination. The results demonstrated that AgNPs/r-GO composites were successfully produced, revealing the formation of micrometer-sized r-GO sheets decorated by AgNPs of approximately 70 nm diameter. Finally, bactericidal and photobactericidal effects of the AgNPs/r-GO composites were tested against Staphylococcus aureus, in which the results showed that the composites presented antimicrobial and photoantimicrobial activities. Moreover, our results demonstrated for the first time, to our knowledge, that an efficient process of bacterial inactivation can be achieved by using AgNPs/r-GO composites under blue light irradiation as a result of three different bacterial killing processes: (i) chemical effect promoted by Ag⁺ ion release from AgNPs; (ii) photocatalytic activity induced by AgNPs/r-GO composites, enhancing the bacterial photoinactivation due to the excited-Plasmons of the AgNPs when anchored on r-GO; and (iii) photodynamic effect produced by bacterial endogenous photosensitizers under blue-light irradiation. In summary, the present findings demonstrated that AgNPs/r-GO can be obtained by a non-toxic procedure with great potential for biomedical-related applications.

Plasmonic Ag decorated graphitic carbon nitride sheets with enhanced visible-light response for photocatalytic water disinfection and organic pollutant removal

Photocatalytic disinfection with high performance is thought to be a promising way for water purification. Herein, plasmonic Ag doped urea-derived graphitic carbon nitride (g-C₃N₄) composites were fabricated via in-situ photo-deposition at room temperature as the visible-light photocatalyst. Scan electron microscopy and transmission electron microscopy images showed the uniform dispersion of Ag nanoparticles on the surface of g-C₃N₄ sheet, which facilitated the synergistic effect of antibacterial performance from Ag and photocatalytic property from Ag/g-C₃N₄ composites. Photocatalytic water disinfection against Escherichia coli with visible light was performed to demonstrate the improved photocatalytic property with assistance of Ag. The 3-Ag/g-C₃N₄ exhibited the best bactericidal performance by inactivating all bacteria within 120 min with damaged cell membranes of Escherichia coli observed by scan electron microscopy and transmission electron microscopy images. Photoluminescence spectra, steady-state surface photovoltage spectra, photocurrent response, and electrochemical impedance spectra results revealed that Ag nanoparticles inhibited the recombination of photo-generated e^- and h⁺ pairs and further reinforced the photocatalytic performance of g-C₃N₄. Scavenger experiments indicated that h⁺ produced on valence band of g-C₃N₄ dominated the photocatalytic disinfection process against Escherichia coli. This work further proved Ag/g-C₃N₄ showed great potential in photocatalytic water disinfection under visible-light irradiation.

Well-Defined Gold Nanorod/Polymer Hybrid Coating with Inherent Antifouling and Photothermal Bactericidal Properties for Treating an Infected Hernia

Biomedical device-associated infection (BAI) is a great challenge in modern clinical medicine. Therefore, developing efficient antibacterial materials is significantly important and meaningful for the improvement of medical treatment and people's health. In the present work, we developed a strategy of surface functionalization for multifunctional antibacterial applications. A functionalized polyurethane (PU, a widely used biomedical material for hernia repairing) surface (PU-Au-PEG) with inherent antifouling and photothermal bactericidal properties was readily prepared based on a near-infrared (NIR)-responsive organic/inorganic hybrid coating which consists of gold nanorods (Au NRs) and polyethylene glycol (PEG). The PU-Au-PEG showed a high efficiency to resist adhesion of bacteria and exhibited effective photothermal bactericidal properties under 808 nm NIR irradiation, especially against multidrug-resistant bacteria. Furthermore, the PU-Au-PEG could inhibit biofilm formation long term. The biocompatibility of PU-Au-PEG was also proved by cytotoxicity and hemolysis tests. The in vivo photothermal antibacterial properties were first verified by a subcutaneous implantation animal model. Then, the anti-infection performance in a clinical scenario was studied with an infected hernia model. The results of animal experiment studies demonstrated excellent in vivo anti-infection performances of PU-Au-PEG. The present work provides a facile and promising approach to develop multifunctional biomedical devices.

Zn2+-assisted photothermal therapy for rapid bacteria-killing using biodegradable humic acid encapsulated MOFs

Bacterial infection is seriously threatening human health all over the world, especially with the emergence of increasing drug-fast bacteria. It is urgent to develop a drug-free strategy to kill bacteria rapidly and efficiently. In this work, humic acid (HuA) encapsulated zeolitic imidazole framework-8 (ZIF-8) (HuA@ZIF-8) nanocomposites are synthesized by the in-situ growth of ZIF-8 on the surface of polyvinylpyrrolidone (PVP)-modified HuA. The synthesized nanocomposites possesses good photothermal effects, i.e., the temperature increased to 59.4 °C under the particle concentration of 1000 μg/mL with 10 min NIR irradiation. In addition, NIR irradiation can also control the release of Zn²⁺ from the composites. The good photothermal effects originate from HuA that can effectively absorb NIR light. The controlled release of Zn²⁺ is ascribed to the induced-dissociation of ZIF-8 under NIR light irradiation. The synergistic action of photothermal therapy and release of zinc ions contributes to the excellent antibacterial efficiency of HuA@ZIF-8 within a short time, i.e. 99.59 % and 99.37 % against Staphylococcus aureus and Escherichia coli with 20 min NIR irradiation, respectively. This work provides a promising strategy to develop a light-responsive platform with good biodegradability and low cost for rapid and effective sterilization.

Fe-TCPP@CS nanoparticles as photodynamic and photothermal agents for efficient antimicrobial therapy

Photodynamic and photothermal agents for efficient antimicrobial therapy.

MnO2-Based nanosystems for cancer therapy

Recent achievements of MnO₂-based nanosystems for various cancer therapies are comprehensively reviewed.

Two-dimensional nanomaterials beyond graphene for antibacterial applications: current progress and future perspectives

The marked augment of drug-resistance to traditional antibiotics underlines the crying need for novel replaceable antibacterials. Research advances have revealed the considerable sterilization potential of two-dimension graphene-based nanomaterials. Subsequently, two-dimensional nanomaterials beyond graphene (2D NBG) as novel antibacterials have also demonstrated their power for disinfection due to their unique physicochemical properties and good biocompatibility. Therefore, the exploration of antibacterial mechanisms of 2D NBG is vital to manipulate antibacterials for future applications. Herein, we summarize the recent research progress of 2D NBG-based antibacterial agents, starting with a detailed introduction of the relevant antibacterial mechanisms, including direct contact destruction, oxidative stress, photo-induced antibacterial, control drug/metallic ions releasing, and the multi-mode synergistic antibacterial. Then, the effect of the physicochemical properties of 2D NBG on their antibacterial activities is also discussed. Additionally, a summary of the different kinds of 2D NBG is given, such as transition-metal dichalcogenides/oxides, metal-based compounds, nitride-based nanomaterials, black phosphorus, transition metal carbides, and nitrides. Finally, we rationally analyze the current challenges and new perspectives for future study of more effective antibacterial agents. This review not only can help researchers grasp the current status of 2D NBG antibacterials, but also may catalyze breakthroughs in this fast-growing field.

Electrochemical Preparation of Synergistic Nanoantimicrobials

The rapid spreading of resistance among common bacterial pathogens towards the misused antibiotics/disinfectant agents has drawn much attention worldwide to bacterial infections. In light of this, the present work aimed at the realization of core-shell nanoparticles possessing remarkable antimicrobial properties thanks to the synergistic action of the metal core and the disinfectant shell. Copper nanoparticles stabilized by benzalkonium chloride were prepared, characterized, and implemented in poly-vinyl-methyl ketone to obtain nanoantimicrobial composite coatings. Bioactivity tests are reported, proving the excellent disinfectant properties of the proposed nanomaterials, as compared to one of the well-known and strongest silver-based nanoantimicrobials. Applications are also briefly described.

Multifunctional Magnetic Copper Ferrite Nanoparticles as Fenton-like Reaction and Near-Infrared Photothermal Agents for Synergetic Antibacterial Therapy

Synergistic therapeutic strategies for bacterial infection have attracted extensive attentions owing to their enhanced therapeutic effects and less adverse effects compared with monotherapy. Herein, we report a novel synergistic antibacterial platform that integrates the nanocatalytic antibacterial therapy and photothermal therapy (PTT) by hemoglobin-functionalized copper ferrite nanoparticles (Hb-CFNPs). In the presence of a low concentration of hydrogen peroxide (H₂O₂), the excellent Fenton and Fenton-like reaction activity of Hb-CFNPs can effectively catalyze the decomposition of H₂O₂ to produce hydroxyl radicals (·OH), rendering an increase in the permeability of the bacterial cell membrane and the sensitivity to heat. With the assistance of NIR irradiation, hyperthermia generated by Hb-CFNPs can induce the death of the damaged bacteria. Additionally, owing to the outstanding magnetic property of Hb-CFNPs, it can improve the photothermal efficiency by about 20 times via magnetic enrichment, which facilitates to realize excellent bactericidal efficacy at a very low experimental dose (20 μg/mL). In vitro antibacterial experiment shows that this synergistic antibacterial strategy has a broad-spectrum antibacterial property against Gram-negative Escherichia coli (E. coli, 100%) and Gram-positive Staphylococcus aureus (S. aureus, 96.4%). More importantly, in vivo S. aureus-infected abscess treatment studies indicate that Hb-CFNPs can serve as an antibacterial candidate with negligible toxicity to realize synergistic treatment of bacterial infections through catalytic and photothermal effects. Accordingly, this study proposes a novel, high-efficiency, and multifunctional therapeutic system for the treatment of bacterial infection, which will open up a new avenue for the design of synergistic antibacterial systems in the future.