Photothermal Antibacterial Activity Research Articles

Biological and structural properties of graphene oxide/curcumin nanocomposite incorporated chitosan as a scaffold for wound healing application

AimsThe purpose of this research is to fabricate chitosan (CS)/graphene oxide (GO)/curcumin (Cur) 3D scaffolds through the freeze-drying method for wound dressing applications. Main methodsGO is produced by Hammer's method; then, it is characterized by X-ray diffraction and TEM analysis. Fabricated scaffolds are characterized by FTIR, FESEM, AFM, water vapor transmission rate, PBS absorption, contact angle, tensile strength, porosity measurement, biodegradability, and drug release methods. The cell viability and morphology of NIH/3 T3 cells are investigated by WST assay kit and FESEM analysis, and the antibacterial activity of scaffolds is determined by the optical density (OD) method. The photothermal antibacterial activity is characterized by NIR irradiation, too. Key findingsThe mean pore diameter of scaffolds adjusted by the incorporation of about 0–1.5%wt. of GO/Cur nanocomposite into CS matrix, decreasing from 87 to 40 μm that can be attributed to the intermolecular bonds between CS and GO/Cur nanocomposite. Besides, the PBS absorption of scaffolds enhances by the addition of GO/Cur, especially 1% of it. Furthermore, the overall average of cell viability of nanocomposite scaffolds is about 95%, and the FESEM images show that NIH/3T3 fibroblasts well spread on the nanocomposite scaffolds. GO/Cur has a significant influence on the antibacterial activity of CS scaffolds as CS/GO/Cur 0.5 scaffold diminishes the bacterial growth to about 52% of the control sample's growth. SignificanceThe results evidence the antibacterial CS/GO/Cur scaffolds are excellent supports for cell growth and proliferation, and they could be promising candidates for wound dressing applications.

Size-Dependent Modulation of Polydopamine Nanospheres on Smart Nanoprobes for Detection of Pathogenic Bacteria at Single-Cell Level and Imaging-Guided Photothermal Bactericidal Activity

Pathogenic bacterial fouling in agriculture and food-associated products poses mounting food safety concerns today. Efficient integration of precise tracking and on-demand bacterial killing to achieve the source control of pathogenic bacteria at the single-cell level is one of the most valuable antifouling methods for safeguarding food safety but remains unexplored. Here, we report an all-in-one design strategy as a proof of concept to establish a stimuli-responsive nanoprobe PDANSs-FAM-Apt for the detection of Staphylococcus aureus (S. aureus) at the single-cell level, which could be capable of guiding the on-demand photothermal killing of bacteria upon near-infrared (NIR) light irradiation. By examining the size-dependent modulation of the fluorescence resonance energy transfer efficiency to polydopamine nanospheres (PDANSs), PDANSs-FAM-Apt was finally assembled by 6-carboxyfluorescein-terminated S. aureus, binding the aptamer (FAM-Apt) and PDANSs at ∼258 nm through π-π stacking interactions. As a result, PDANSs-FAM-Apt exhibits a remarkable fluorescence enhancement (∼261-fold) to S. aureus with a satisfactory detection limit of 1.0 cfu/mL, allowing for assay at the single-cell level and thus ultralow background fluorescence imaging of S. aureus as well as its biofilms. Moreover, PDANSs-FAM-Apt shows a high photothermal bactericidal property upon NIR light irradiation, endowing it with the strong capacity to efficiently produce heat for destroying S. aureus and its biofilms with the guidance of imaging results. This work emphasizes the versatility of using the combination of stimuli-responsive fluorescence imaging dependent on the PDANS size modulation and NIR light-activated photothermal antibacterial activity to design stimuli-responsive nanoprobes with an improved precision for pathogenic bacteria monitoring and source controlling, which opens a promising antifouling avenue to eliminate bacteria and disrupt bacterial biofilms in agriculture and food-related industries.

Polyethylenimine modified MoS2 nanocomposite with high stability and enhanced photothermal antibacterial activity

The widespread bacterial infections accompanied by drug resistance, resulting from the abuse of traditional antibiotics, motivates researchers to develop effective antibacterial substitutes. Current researches have focused on positive antibacterial composites to promote interactions with bacteria, however facing challenges of unstable binding and low antibacterial efficiency. Here, we used covalent bonds to construct polyethylenimine modified Molybdenum disulfide (MoS2-PEI) nanocomposite to achieve tight combination and improve stability. We employed bifunctional groups including thiol and carboxylate group as a linker to firmly connect MoS2 and PEI. The covalent bonding strategy not only enhanced the stability of MoS2-PEI but also promoted the binding of MoS2-PEI to the surface of bacteria through electrostatic interaction. The distribution of MoS2-PEI around bacteria studies proved that positively charged MoS2-PEI could efficiently bind with negative bacteria. These two binding modes achieved accumulation of MoS2-PEI around bacteria and shortened the distance of reactive oxygen species (ROS) destruction. Moreover, the photothermal property of MoS2-PEI generated deep-penetrating heat and accelerated the oxidative stress. Under NIR light irradiation, MoS2-PEI exhibited synergistically prominent antibacterial efficacy against both Escherichia coli and Staphylococcus aureus and displayed long term bactericidal effect after 1 week storage. This work could contribute as an alternative to improve the effectiveness of current disinfection treatments.

Injectable self-healing supramolecular hydrogels with conductivity and photo-thermal antibacterial activity to enhance complete skin regeneration

Hydrogel dressings with good biocompatibility and the ability to maintain a moist environment at the wound site have great potential for clinical application. Multifunctional injectable self-healing supramolecular hydrogel with conductivity and photo-thermal property as wound dressing to promote wound healing has been not reported. Herein, a series of antibacterial, injectable self-healing and conductive supramolecular hydrogels were fabricated through host-guest interaction based on quaternized chitosan-graft-cyclodextrin (QCS-CD), quaternized chitosan-graft-adamantane (QCS-AD) and graphene oxide-graft-cyclodextrin (GO-CD) polymer solutions which combined the good antibacterial activity of QCS and photo-thermal property of reduced graphene oxide (rGO). These supramolecular hydrogels wound dressings have a conductivity value similar to that of the skin and a rapid self-healing behavior, and have great antibacterial property against E. coli (gram-negative), S. aureus (gram-positive), and multi-drug resistant bacteria (such as Methicillin-resistant Staphylococcus aureus, MRSA). Furthermore, QCS-CD-AD/GO4 (0.4 wt% of rGO in the sample) shows a good balance between antibacterial activity, cell proliferation and hemocompatibility. Compared with commercial dressings (Tegaderm™ film) and QCS-CD-AD/GO0, the hydrogel QCS-CD-AD/GO4 significantly accelerated the in vivo healing process of full-thickness wounds with promoted epidermis and granulation tissue thickness, increased area coverage of collagen, and up-regulated VEGF expression. In short, these antibacterial, conductive self-healing supramolecular hydrogels are promising biomaterials as wound dressings for full-thickness skin repair.

Physical Double‐Network Hydrogel Adhesives with Rapid Shape Adaptability, Fast Self‐Healing, Antioxidant and NIR/pH Stimulus‐Responsiveness for Multidrug‐Resistant Bacterial Infection and Removable Wound Dressing

AbstractDeveloping physical double‐network (DN) removable hydrogel adhesives with both high healing efficiency and photothermal antibacterial activities to cope with multidrug‐resistant bacterial infection, wound closure, and wound healing remains an ongoing challenge. An injectable physical DN self‐healing hydrogel adhesive under physiological conditions is designed to treat multidrug‐resistant bacteria infection and full‐thickness skin incision/defect repair. The hydrogel adhesive consists of catechol–Fe3+ coordination cross‐linked poly(glycerol sebacate)‐co‐poly(ethylene glycol)‐g‐catechol and quadruple hydrogen bonding cross‐linked ureido‐pyrimidinone modified gelatin. It possesses excellent anti‐oxidation, NIR/pH responsiveness, and shape adaptation. Additionally, the hydrogel presents rapid self‐healing, good tissue adhesion, degradability, photothermal antibacterial activity, and NIR irradiation and/or acidic solution washing‐assisted removability. In vivo experiments prove that the hydrogels have good hemostasis of skin trauma and high killing ratio for methicillin‐resistant staphylococcus aureus (MRSA) and achieve better wound closure and healing of skin incision than medical glue and surgical suture. In particular, they can significantly promote full‐thickness skin defect wound healing by regulating inflammation, accelerating collagen deposition, promoting granulation tissue formation, and vascularization. These on‐demand dissolvable and antioxidant physical double‐network hydrogel adhesives are excellent multifunctional dressings for treating in vivo MRSA infection, wound closure, and wound healing.

High Stability Thiol-Coated Gold Nanostars Monolayers with Photo-Thermal Antibacterial Activity and Wettability Control.

The adhesion and proliferation of bacteria on abiotic surfaces pose challenges in both health care and industrial applications. Gold nanostars (GNSs) monolayers grafted on glass have demonstrated to exert antibacterial action due to their photo-thermal features. Here, these GNS layers were further functionalized using thiols monolayers, in order to impart different wettability to the surfaces and thus adding a feature that could help to fight bacterial proliferation. Thiol that has different functional groups was used and the thiol-protected surfaces were characterized by means of UV-vis spectroscopy, contact angles, SEM and surface enhanced Raman spectroscopy (SERS). We verified that (i) coating with the proper thiol allows us to impart high hydrophilicity or hydrophobicity to the surfaces (with contact angle values ranging from 10 to 120°); (ii) GNS monolayers are strongly stabilized by functionalization with thiols, with shelf stability increasing from a few weeks to more than three months and (iii) photo-thermal features and subsequent antibacterial effects caused by hyperthermia are not changed by thiols layers, allowing us to kill at least 99.99% of representative bacterial strains.

Adhesive Hemostatic Conducting Injectable Composite Hydrogels with Sustained Drug Release and Photothermal Antibacterial Activity to Promote Full-Thickness Skin Regeneration During Wound Healing.

Developing injectable nanocomposite conductive hydrogel dressings with multifunctions including adhesiveness, antibacterial, and radical scavenging ability and good mechanical property to enhance full-thickness skin wound regeneration is highly desirable in clinical application. Herein, a series of adhesive hemostatic antioxidant conductive photothermal antibacterial hydrogels based on hyaluronic acid-graft-dopamine and reduced graphene oxide (rGO) using a H2 O2 /HPR (horseradish peroxidase) system are prepared for wound dressing. These hydrogels exhibit high swelling, degradability, tunable rheological property, and similar or superior mechanical properties to human skin. The polydopamine endowed antioxidant activity, tissue adhesiveness and hemostatic ability, self-healing ability, conductivity, and NIR irradiation enhanced in vivo antibacterial behavior of the hydrogels are investigated. Moreover, drug release and zone of inhibition tests confirm sustained drug release capacity of the hydrogels. Furthermore, the hydrogel dressings significantly enhance vascularization by upregulating growth factor expression of CD31 and improve the granulation tissue thickness and collagen deposition, all of which promote wound closure and contribute to a better therapeutic effect than the commercial Tegaderm films group in a mouse full-thickness wounds model. In summary, these adhesive hemostatic antioxidative conductive hydrogels with sustained drug release property to promote complete skin regeneration are an excellent wound dressing for full-thickness skin repair.

Designing distance dependent SERS assay for monitoring photothermal antibacterial activity response

This communication reports, for the first time, the design of distance dependent SERS assay for monitoring the photothermal antibacterial activity process.