Integration of antimicrobial peptides and gold nanorods for bimodal antibacterial applications

β-Carotene laden antibacterial and antioxidant gelatin/polyglyceryl stearate nano-hydrogel system for burn wound healing application

Worldwide, burn wounds are severe health issues prone to bacterial infections and challenging to treat with traditional wound dressings. Therefore, a highly desirable biological macromolecules-based wound dressing with good antioxidant, antibacterial, biocompatible, and a large surface area is required. Herein, aim to develop a biological macromolecules-based physically cross-linked gelatin/polyglyceryl stearate/graphene oxide (GPGO) hydrogel to treat burn wounds. Four sets of hydrogels were prepared by varying GO concentrations. FT-IR, FE-SEM, viscosity analysis, mechanical and thermal stability confirmed the successful preparation of hydrogels with desired properties. Further, β-carotene (0.5 mg/mL) was encapsulated in hydrogels to enhance the antioxidant activity, and a cumulative release as well as kinetics at pH 6.4 and 7.4 was performed. With an increase in GO concentration, hydrogels showed sustained release of β-carotene. Among all, GPGO-3 β hydrogel showed the highest antioxidant potency (57.75 %), hemocompatible (<5 %), cytocompatible (viable with NIH 3T3 cells), cell migration, proliferation, and in vitro wound healing. Also, GPGO-3 β hydrogel showed efficient antibacterial activity (%inhibition of 85.5 % and 80.2 % and zone of 11 mm and 9.8 mm against S. aureus and E. coli). These results demonstrated the ability of GPGO-3 β hydrogel as a promising candidate for burn wound healing applications.

Near-infrared light-responsive multifunctional hydrogel releasing peptide-functionalized gold nanorods sequentially for diabetic wound healing

Treatment for chronic diabetic wounds remains a clinical challenge. Wound healing process occurs in three phases: inflammation, proliferation and remodeling. Several factors including bacterial infection, decreased local angiogenesis and diminished blood supply delay wound healing. There is an urgent need to develop wound dressings with multiple biological effects for different stages of diabetic wound healing. Here, we develop a multifunctional hydrogel with two-stage sequential release upon near-infrared (NIR) stimulation, antibacterial activity and pro-angiogenic efficacy. This hydrogel consists of covalently crosslinked bilayer structure, with the lower thermoresponsive poly(N-isopropylacrylamide)/gelatin methacrylate (NG) layer and the upper highly stretchable alginate/polyacrylamide (AP) layer embedding different peptide-functionalized gold nanorods (AuNRs) in each layer. Antimicrobial peptide-functionalized AuNRs released from NG layer exert antibacterial effects. After NIR irradiation, the photothermal transition efficacy of AuNRs synergistically enhances bactericidal efficacy. The contraction of thermoresponsive layer also promotes the release of embedded cargos during early stage. The pro-angiogenic peptide-functionalized AuNRs released from AP layer promote angiogenesis and collagen deposition by accelerating fibroblast and endothelial cell proliferation, migration and tube formation during the subsequent healing phases. Therefore, the multifunctional hydrogel with effective antibacterial activity, pro-angiogenic efficacy and sequential release behaviors is a potential biomaterial for diabetic chronic wound healing.

Antibacterial Pathways in Transition Metal-Based Nanocomposites: A Mechanistic Overview

Across the planet, outbreaks of bacterial illnesses pose major health risks and raise concerns. Photodynamic, photothermal, and metal ion release effects of transition metal-based nanocomposites (TMNs) were recently shown to be highly effective in reducing bacterial resistance and upsurges in outbreaks. Surface plasmonic resonance, photonics, crystal structures, and optical properties of TMNs have been used to regulate metal ion release, produce oxidative stress, and generate heat for bactericidal applications. The superior properties of TMNs provide a chance to investigate and improve their antimicrobial actions, perhaps leading to therapeutic interventions. In this review, we discuss three alternative antibacterial strategies based on TMNs of photodynamic therapy, photothermal therapy, and metal ion release and their mechanistic actions. The scientific community has made significant efforts to address the safety, effectiveness, toxicity, and biocompatibility of these metallic nanostructures; significant achievements and trends have been highlighted in this review. The combination of therapies together has borne significant results to counter antimicrobial resistance (4-log reduction). These three antimicrobial pathways are separated into subcategories based on recent successes, highlighting potential needs and challenges in medical, environmental, and allied industries.

Antimicrobial peptide functionalized gold nanorods combining near-infrared photothermal therapy for effective wound healing

Photothermal therapy using laser activated gold nanorods (AuNRs) is a strategy for treatment of bacterial infections. Nevertheless, it also exerts cytotoxicity against human cells which leads to adverse effects in healthy human tissues and limits the applicable dose. Functionalization of AuNRs with a selective antimicrobial peptide (AMP) with higher selectivity for bacteria over human cells is a promising strategy for increasing the selectivity of the AuNRs for bacteria, hence increasing their cellular uptake by the bacteria in order to achieve stronger antimicrobial effects with lower doses of AuNRs without damaging the human cells. In this study, the surface of AuNRs was functionalized with a short AMP named C-At5 and the efficiency of the peptide functionalized AuNRs in killing gram-positive and gram-negative bacteria was evaluated in vitro as well as their potential for facilitating wound healing in a mouse model of wound infection with and without application of laser. The peptide-conjugated AuNRs exhibited higher antibacterial activity in vitro compared to the plain AuNRs both in the presence and absence of laser irradiation. Furthermore, AuNR@C-At5 had very low toxicity against human skin fibroblasts and human red blood cells indicating their higher biocompatibility compared to the plain AuNRs. Treatment of wounded mice with AuNR@C-At5 accelerated the wound healing process which was further enhanced by applying laser. The system developed in this study has great potential for customization for specific antimicrobial or antifungal therapy via conjugation of different types of AMPs with higher selectivity and can therefore serve as a guide for any future attempts in this regard.

Metal nanoparticles against multi-drug-resistance bacteria

Antimicrobial-resistant (AMR) bacterial infections remain a significant public health concern. The situation is exacerbated by the rapid development of bacterial resistance to currently available antimicrobials. Metal nanoparticles represent a new perspective in treating AMR due to their unique mechanisms, such as disrupting bacterial cell membrane potential and integrity, biofilm inhibition, reactive oxygen species (ROS) formation, enhancing host immune responses, and inhibiting RNA and protein synthesis by inducing intracellular processes. Metal nanoparticles (MNPs) properties such as size, shape, surface functionalization, surface charges, and co-encapsulated drug delivery capability all play a role in determining their potential against multidrug-resistant bacterial infections. Silver, gold, zinc oxide, selenium, copper, cobalt, and iron oxide nanoparticles have recently been studied extensively against multidrug-resistant bacterial infections. This review aims to provide insight into the size, shape, surface properties, and co-encapsulation of various MNPs in managing multidrug-resistant bacterial infections.

Advances in Nanostructures for Antimicrobial Therapy

Microbial infections caused by a variety of drug-resistant microorganisms are more common, but there are fewer and fewer approved new antimicrobial chemotherapeutics for systemic administration capable of acting against these resistant infectious pathogens. Formulation innovations of existing drugs are gaining prominence, while the application of nanotechnologies is a useful alternative for improving/increasing the effect of existing antimicrobial drugs. Nanomaterials represent one of the possible strategies to address this unfortunate situation. This review aims to summarize the most current results of nanoformulations of antibiotics and antibacterial active nanomaterials. Nanoformulations of antimicrobial peptides, synergistic combinations of antimicrobial-active agents with nitric oxide donors or combinations of small organic molecules or polymers with metals, metal oxides or metalloids are discussed as well. The mechanisms of actions of selected nanoformulations, including systems with magnetic, photothermal or photodynamic effects, are briefly described.

Antimicrobial peptide-based materials: opportunities and challenges

The multifunctional properties of antimicrobial peptides (AMPs) make them attractive candidates for the treatment of various diseases. AMPs are considered alternatives to antibiotics due to the rising number of multidrug-resistant...

Delineating the Role of Tailored Gold Nanostructures at the Biointerface

Gold (Au) has emerged as a superior element, because of its widespread applications in electronic and medical fields. The desirable physical, chemical, optical, and inherent enzyme-like properties of Au are efficiently exploited for detection, diagnostic, and therapeutic purposes. Au offers a unique advantage of fabricating gold nanostructures (GNS) having exact physical, chemical, optical, and enzyme-like properties required for the specific biomedical application. In this Review, the emerging trend of GNS for various biomedical applications is highlighted. Some notable structural and chemical modifications achieved for the detection of biomolecules, pathogens, diagnosis of diseases, and therapeutic applications are discussed in brief. The limitations of GNS during biomedical usage are highlighted and the way forward to overcome these limitations are discussed.

Silica-supported near-infrared carbon dots and bicarbonate nanoplatform for triple synergistic sterilization and wound healing promotion therapy

Widespread bacterial infection and the emergence of antibiotic resistance exhibit an increasing threat to public health. Additionally, chronic wounds caused by bacterial infection have become a major challenge and threat in medical. Therefore, it is of great significance to explore effective and safe nanomaterials which possess antibacterial and wound healing promotion performance. Herein, we developed silica-supported near-infrared carbon dots (QPCuRC@MSiO₂) and bicarbonate (BC) nanoplatform (BC/QPCuRC@MSiO₂@PDA), which possess triple synergistic antibacterial including quaternary ammonium compounds (QACs), photothermal therapy (PTT), and photodynamic therapy (PDT). Meanwhile, the nanoplatform realized the controlled release of CO₂ in situ triggered by 808 nm laser irradiation for wound healing. In vitro and in vivo antibacterial assays displayed that the BC/QPCuRC@MSiO₂@PDA possess excellent antibacterial property, the antibacterial rate up to 99.6% and 99.99% to Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus), respectively. Wound healing evaluation proved that suitable release of CO₂ could promote the process of infected wound healing, and the wound healing rate up to 100% after treatment for 14 days. Additionally, the cellular imaging experiment revealed that the BC/QPCuRC@MSiO₂@PDA could be considered as fluorescence probe. Together, these results demonstrated that the BC/QPCuRC@MSiO₂@PDA have great potential in biomedical field.

Surface engineering strategies of gold nanomaterials and their applications in biomedicine and detection

Gold nanomaterials have potential applications in biosensors and biomedicine due to their controllable synthesis steps, high biocompatibility, low toxicity and easy surface modification. However, there are still various limitations including low water solubility and stability, which greatly affect their applications. In addition, some synthetic methods are very complicated and costly. Therefore, huge efforts have been made to improve their properties. This review mainly introduces the strategies for surface modification of gold nanomaterials, such as amines, biological small molecules and organic small molecules as well as the biological applications of these functionalized AuNPs. We aim to provide effective ideas for better functionalization of gold nanomaterials in the future.

Gold Nanomaterials as a Promising Integrated Tool for Diagnosis and Treatment of Pathogenic Infections-A Review

This review summarizes research on functionalized gold nanomaterials as pathogen detection sensors and pathogen elimination integrated tools. After presenting the challenge of current severe threat from pathogenic bacteria and the increasingly serious growth rate of drug resistance, the first section mainly introduces the conspectus of gold nanostructures from synthesis, characterization, physicochemical properties and applications of gold nanomaterials. The next section deals with gold nanomaterials-based pathogen detection sensors such as colorimetric sensors, fluorescence sensors and Surface-Enhanced Raman Scattering sensors. We then discuss strategies based on gold nanomaterials for eliminating pathogenic infections, such as the dual sterilization strategy for grafting gold nanomaterials with antibacterial substances, photothermal antibacterial and photodynamic antibacterial methods. The fourth part briefly introduces the comprehensive strategy for diagnosis and sterilization of pathogen infection based on gold nanomaterials, such as the diagnosis and treatment strategy for pathogen infection using Roman signals real-time monitoring and photothermal sterilization. A concluding section that summarizes the current status and challenges of the novel diagnosis and treatment integrated strategy for pathogenic infections, gives an outlook on potential future perspectives.

Recent advances in design of antimicrobial peptides and polypeptides toward clinical translation

The recent outbreaks of infectious diseases caused by multidrug-resistant pathogens have sounded a piercing alarm for the need of new effective antimicrobial agents to guard public health. Among different types of candidates, antimicrobial peptides (AMPs) and the synthetic mimics of AMPs (SMAMPs) have attracted significant enthusiasm in the past thirty years, due to their unique membrane-active antimicrobial mechanism and broad-spectrum antimicrobial activity. The extensive research has brought many drug candidates into clinical and pre-clinical development. Despite tremendous progresses have been made, several major challenges inherent to current design strategies have slowed down the clinical translational development of AMPs and SMAMPs. However, these challenges also triggered many efforts to redesign and repurpose AMPs. In this review, we will first give an overview on AMPs and their synthetic mimics, and then discuss the current status of their clinical translation. Finally, the recent advances in redesign and repurposing AMPs and SMAMPs are highlighted.

A series of carboxymethyl cellulose-based antimicrobial peptide mimics were synthesized for antimicrobial applications

Inspired by antimicrobial peptides (AMP) which could alleviate drug resistance pressure, antimicrobial peptide mimics (AMPMs) were designed timely. Here, carboxymethyl cellulose (CMC) -based AMPMs were constructed by introducing different diamines on CMC effectively. Firstly, CMC was degraded to be oligomers with different molecular weights, followed by amination reactions with different diamines respectively. After protonation, a series of AMPMs with different structures were synthesized successfully. Their antibacterial effect has been evaluated by dynamic growth curves and microdilution method. The images snapped by the confocal laser scanning microscope and transmission electron microscope have fully proved its great lethality. And the antibacterial mechanism measured by flow cytometry analysis and zeta potential detection demonstrated that the destruction of membrane potential leads to bacteria death. The excellent blood compatibility and negligible drug resistance has also been confirmed. In addition, the synthesis method is simple and environmental-friendly.