Intrinsic Antibacterial Properties Research Articles

Self-healing hydrogel from poly(aspartic acid) and dextran with antibacterial property for burn wound healing

Designing hydrogel dressing with intrinsic antibacterial property to promote skin injury recovery remains a significant challenge. In this research, poly(aspartic hydrazide) with grafted betaine (PAHB) was designed and reacted with oxidized dextran (OD) to fabricate biodegradable PAHB/OD hydrogel and its application as wound dressing was systematically investigated. The PAHB/OD hydrogels exhibited fast gelation, strong tissue adhesion, preferable mechanical properties and biocompatibility. The grafted betaine endowed the hydrogel with antibacterial property and antibacterial rate enhanced through photothermal performance of composited CuS nanoparticles under near infrared (NIR) radiation. The CuS composited PAHB/OD hydrogel (CuS/hydrogel) with microporous morphology was used as burn wound dressing with loaded anti-inflammatory drug diclofenac sodium (DS) in mouse model. The results showed the DS loaded CuS/hydrogel (CuS@DS/hydrogel) promoted the tissue regeneration and suppressed the inflammatory response. The histological analysis and immunohistochemical expression confirmed the CuS@DS/hydrogel promote angiogenesis of the burn wound by regulating the expression of inflammatory cytokines (IL-6 and CD68) and vascular endothelial growth factor (VEGF). Overall, the CuS@DS/hydrogel hydrogel is a promising candidate as wound dressing due to its tissue adhesive, antioxidant, antibacterial and anti-inflammatory activities.

Polyhydroxy structure orchestrates the intrinsic antibacterial property of acrylamide hydrogel as a versatile wound-healing dressing.

Hydrogel is considered as a promising candidate for wound dressing due to its tissue-like flexibility, good mechanical properties and biocompatibility. However, traditional hydrogel dressings often fail to fulfill satisfied mechanical, antibacterial, and biocompatibility properties simultaneously, due to the insufficient intrinsic bactericidal efficacy and the addition of external antimicrobial agents. In this paper, hydroxyl-contained acrylamide monomers, N-Methylolacrylamide (NMA) and N-[Tris (hydroxymethyl)methyl] acrylamide (THMA), are employed to prepare a series of polyacrylamide hydrogel dressings xNMA-yTHMA, where x and y represent the mass fractions of NMA and THMA in the hydrogels. We have elucidated that the abundance of hydroxyl groups determines the antibacterial effect of the hydrogels. Particularly, hydrogel 35NMA-5THMA exhibits excellent mechanical properties, with high tensile strength of 259kPa and large tensile strain of 1737%. Furthermore, the hydrogel dressing 35NMA-5THMA demonstrates remarkable inherent antibacterial without exogenous antimicrobial agents owing to the existence of abundant hydroxyl groups. Besides, hydrogel dressing 35NMA-5THMA possesses excellent biocompatibility, in view of marginal cytotoxicity, low hemolysis ratio, and negligible inflammatory response and organ toxicity to mice during treatment. Encouragingly, hydrogel 35NMA-5THMA drastically promote the healing of bacteria-infected wound in mice. This study has revealed the importance of polyhydroxyl in the antibacterial efficiency of hydrogels and provided a simplified strategy to design wound healing dressings with translational potential.

Polymers with one free gallic acid per monomer unit. Controlled synthesis and intrinsic antioxidant/antibacterial properties

The development of bio-based thermoplastics is rapidly growing due to the depletion of fossil fuel reserves but also in the hope of obtaining polymers with original properties. Herein, we report the controlled synthesis of original homopolymers derived from gallic acid, one of the well-known natural polyphenols that exhibits various health-promoting effects. More precisely, acrylate, methacrylate and acrylamide monomers based on a protected gallic acid are firstly obtained by a rethought multistep scheme. Then, a controlled photo-mediated RAFT (Reversible Addition Fragmentation chain Transfer) polymerization is carried out before a final deprotection. By this way, original polymers bearing a free gallic acid as a lateral substituent on each monomer unit are described. The intrinsic antibacterial and antioxidant properties of these polymers are highlighted and compared with those of gallic acid.

Synergistic cobalt‑copper metal-organic framework anchored amino-functionalized cellulose for antibiotic degradation: Interfacial engineering and mechanism insight.

Improving electron transfer rate of Co species and inhibiting aggregation of metal-organic frameworks (MOFs) particles are essential prerequisites for activating advanced oxidation process in wastewater treatment field. Here, we exploit Cu species with variable valence states to accelerate electron transfer of Co species and then to boost the unsatisfactory degradation efficiency for refractory pharmaceuticals via in-situ growth of copper and cobalt species on l-lysine functionalized carboxylated cellulose nanofibers. Utilizing the synergistic interplay of Co sites and deliberately exposed Cu0/Cu1+ atoms, the subtly designed catalyst exhibited a surprising degradation efficiency (~100 %) toward tetracycline hydrochloride within 10 min (corresponding to a catalytic capacity of 267.71 mg/g) without adjusting temperature and pH. Meanwhile, the catalyst displays good recyclability, well tolerance for coexisting ions and excellent antibacterial performance derived from the intrinsic antibacterial property of Cu-MOF. This research provided a novel strategy to construct MOFs-cellulose materials toward degrading various stubborn antibiotic pollutants.

Green Additives in Chitosan-based Bioplastic Films: Long-term Stability Assessment and Aging Effects.

Although biomass-based alternatives for the manufacturing of bioplastic films are an important aspect of a more sustainable future, their physicochemical properties need to be able to compete with the existing market to establish them as a viable alternative. One important factor that is often neglected is the long-term stability of renewables-based functional materials, as they should neither degrade after a day or week, nor last forever. One material showing high potential in this regard, also due to its intrinsic biodegradability and antibacterial properties, is chitosan, which can form stable, self-standing films. We previously showed that green additives introduce a broad tunability of the chitosan-based material properties. In this work, we investigate the long-term stability and related degradation processes of chitosan-based bioplastics by assessing their physicochemical properties over 400 days. It was found that the film properties change similarly for samples stored in the fridge (4 °C, dark) as at ambient conditions (20 °C, light/dark cycles of the day). Additives with high vapor pressure, such as glycerol, evaporate and degrade, causing both brittleness and discoloration. In contrast, films with the addition of crosslinking additives, such as citric acid, show high stability also over a long time, bearing great preconditions for practical applications. This knowledge serves as a stepping-stone to utilizing chitosan as an alternative material for renewable-resourced bioplastic products.

Microenvironment-responsive smart hydrogels with antibacterial activity and immune regulation for accelerating chronic wound healing

Current therapeutic strategies for chronic refractory wounds remain challenge owing to their unfavorable wound microenvironment and poor skin regeneration ability. Thus far, a regimen for effective chronic refractory wounds management involves bacterial elimination, alleviation of oxidative stress, inhibition of inflammatory response, and promotion of angiogenesis. In this work, an injectable glycopeptide hydrogel based on phenylboronic acid-grafted ϵ-polylysine (EPBA) and poly (vinyl alcohol) (PVA) with pH/reactive oxygen species (ROS) dual-responsive properties was prepared, which exerted intrinsic antibacterial and antioxidant properties. ROS-responsive micelles (MIC) loaded with herb-derived Astragaloside IV (AST) are introduced into the hydrogel before gelation. Attributed to the acidic condition and oxidative stress microenvironment of wound bed, the hydrogel gradually disintegrates, and the released EPBA could help to eliminate bacterial. Meanwhile, the subsequential release of AST could help to achieve anti-oxidation, anti-inflammatory, proangiogenic effects, and regulation of macrophage polarization to accelerate chronic wound healing. In addition, the wound repair mechanism of composite hydrogel accelerating skin regeneration was assessed by RNA-sequencing, exploring a range of potential targets and pathway for further study. Collectively, this multifunctional hydrogel dressing, matching different healing stages of tissue remodeling, holds a great potential for the treatment of chronic refractory wounds.

Preparation strategies of mussel-inspired chitosan-based biomaterials for hemostasis.

Chitosan (CS) has been extensively studied in wound care for its intrinsic hemostatic and antibacterial properties. However, CS has limiting hemostasis applications on account of its drawbacks such as poor adhesion in humid environments and water solubility at neutral pH. CS-based biomaterials, inspired by mussel-adhesive proteins, serve as a suggested platform by biomedical science. The reports show that the mussel-inspired CS-based hemostatic structure has negligible toxicity and excellent adhesiveness. Biomedicine has witnessed significant progress in the development of these hemostatic materials. This review summarizes the methods for the modification of CS by mussel-inspired chemistry. Moreover, the general method for preparation of mussel-inspired CS-based biomaterials is briefly discussed in this review. This work is expected to give a better understanding of opportunities and challenges of the mussel-inspired strategy for the functionalization of CS-based biomaterials in hemostasis and wound healing. This review is hoped to provide an important perspective on the preparation of mussel-inspired CS-based hemostatic materials.

“Graphene nanospikes exert bactericidal effect through mechanical damage and oxidative stress”

Microbial contamination of biomedical surfaces is an important clinical challenge, driving the development of new antibacterial materials. Nanoprotrusions on the wing surface of some insects have intrinsic antibacterial and antifouling properties, which inspires fabrication of biomimetic nanopatterns on medical devices. Herein, we report a broad-spectrum bactericidal surface consisting of graphene nanospikes synthesized by plasma-enhanced chemical vapor deposition. Similar coatings have been reported before, but the killing mechanism and main parameters for efficiency of such coatings have not been clarified. We investigated the correlation of anti-biofilm efficiency of graphene nanospikes to their major physicochemical parameters. While height and thickness of nanospikes did not directly correlate with bactericidal effects, edge/defect density showed linear correlation with lethality for both Gram-negative and Gram-positive bacteria. We further demonstrated that the killing mechanism is synergistic, depending on physical rupture of bacterial membranes as well as considerable oxidative damage to the cells. Of note, for the first time, we quantify the level of oxidative stress induced by graphene nanospikes in two bacterial species using genetically encoded biosensors. Our work provides a fundamental understanding of the impact of various parameters of graphene nanostructures on the bactericidal efficiency, enabling rational design of graphene-based bactericidal surfaces.

Enhancement of antibacterial and wound healing capabilities of cotton fabric through the covalent bonding of antibiotic-loaded hydrophobized mesoporous silica nanoparticles

Wound dressings are highly desirable for mitigating pathogenic bacterial infections. Sterilized cotton fabric is a widely used medical dressing, facilitating wound healing, mitigating pathogenic infections, and reducing treatment expenses. Nevertheless, untreated cotton fabric lacks intrinsic antibacterial properties. In this study, we introduced antibiotics-loaded aminopropyl and octadecyl grafted mesoporous silica nanoparticles onto the surface of hydrophobized cotton fabric. The obtained wound dressing exhibited remarkable antibacterial efficacy against Escherichia coli and Staphylococcus aureus through sustained antibiotic release. In vivo assessments verified that this intelligent cotton fabric dressing accelerates wound healing and prevents adhesion to skin tissues. Additionally, the reusability, hydrophobic nature, and straightforward synthesis methodology collectively provide an alternative solution to smart wound dressings for biomedical applications.© 2014 xxxxxxxx. Hosting by Elsevier B.V. All rights reserved.

Directional transport of drug droplets based on structural and wettability gradients on antibacterial Janus wound plaster with hemostatic, antiextravasation, and prehealing properties

The failure of wound healing is majorly attributed to uncontrolled bleeding and bacterial infections. However, developing a wound plaster that can stop bleeding, resist blood extravasation, and realize directional transportation of drugs to promote wound healing remains a significant challenge. Herein, a superhydrophilic/hydrophobic polyvinyl alcohol/chitosan/silver@Thermoplastic polyurethane (PVA/CS/Ag@TPU) Janus membrane with structural and wettability gradients is developed. In this newly developed membrane, water is absorbed from blood via the superhydrophilic layer, which is attached to the wound, and the charge interactions between platelets and the introduced chitosan (CS) promote blood clotting. The capillary pressure resistance (∆p > 0) of the superhydrophilic layer toward the hydrophobic layer prevents blood permeation, thereby reducing blood loss. The favorable ∆p (< 0) of the membrane based on its structural and wettability gradients can realize the directional transportation of drugs that promote wound healing from the hydrophobic to the superhydrophilic layer. The incorporation of CS and silver endows the Janus membrane with intrinsic antibacterial properties (99.9%). The formation of the hydrated layer on the hydrophilic layer imparts a resisting effect, further endowing the membrane with antiadhesion and antibacterial properties. Experiments involving mice with full-thickness skin wounds revealed that the wound-healing rate increased from 87.65% to ~ 100% when the Janus membrane was loaded with the prehealing drug. Moreover, the dressing accelerated wound healing, regenerated epidermal and granulation tissues, promoted collagen formation, and reduced scar size. Thus, this gradient design strategy opens an avenue for the development of next-generation wound dressings.Graphical abstract

Cis-2-Decenoic Acid and Bupivacaine Delivered from Electrospun Chitosan Membranes Increase Cytokine Production in Dermal and Inflammatory Cell Lines.

Wound dressings serve to protect tissue from contamination, alleviate pain, and facilitate wound healing. The biopolymer chitosan is an exemplary choice in wound dressing material as it is biocompatible and has intrinsic antibacterial properties. Infection can be further prevented by loading dressings with cis-2-decenoic acid (C2DA), a non-antibiotic antimicrobial agent, as well as bupivacaine (BUP), a local anesthetic that also has antibacterial capabilities. This study utilized a series of assays to elucidate the responses of dermal cells to decanoic anhydride-modified electrospun chitosan membranes (DA-ESCMs) loaded with C2DA and/or BUP. Cytocompatibility studies determined the toxic loading ranges for C2DA, BUP, and combinations, revealing that higher concentrations (0.3 mg of C2DA and 1.0 mg of BUP) significantly decreased the viability of fibroblasts and keratinocytes. These high concentrations also inhibited collagen production by fibroblasts, with lower loading concentrations promoting collagen deposition. These findings provide insight into preliminary cellular responses to DA-ESCMs and can guide future research on their clinical application as wound dressings.

Photothermal antibacterial antioxidant conductive self-healing hydrogel with nitric oxide release accelerates diabetic wound healing

Diabetic wound healing is affected by insufficient angiogenesis, oxidative damage, and bacterial infection, resulting in a delayed healing process. There is an urgent need to design a novel multifunctional wound dressing for promoting diabetic wound healing. Nitric oxide (NO) represents a promising wound healing agent because of its positive role in angiogenesis. Here, a series of antibacterial antioxidant self-healing conductive multifunctional hydrogels integrating near-infrared (NIR) laser irradiation NO release behavior, were developed based on carboxymethyl chitosan (CMCS), 2,3,4-trihydroxybenzaldehyde (THB), copper chloride (CuCl2), and graphene oxide (GO)-N, N′-di-sec-butyl-N, N′-dinitroso-1,4-phenylenediamine (BNN6) (GO-BNN6, abbreviated as GB), to promote wound healing in Type I diabetes (TID). CMCS/THB/Cu/GB hydrogels show stable mechanical properties, self-healing ability, conductivity, antioxidant properties, intrinsic antibacterial properties, biocompatibility, etc. The addition of GB enabled the hydrogel to exhibit photothermal properties and photothermal-induced antibacterial activity in vitro. More importantly, the CMCS/THB/Cu/GB2 (2 mg/mL of GB in the hydrogel) was able to release NO under NIR laser irradiation. In a full-thickness skin wound model in diabetic mice, CMCS/THB/Cu/GB2 hydrogel combined with NIR laser treatment (CMCS/THB/Cu/GB2+NIR) can significantly accelerate wound contraction, collagen content, and angiogenesis. In conclusion, these multifunctional photothermal conductive antioxidant self-healing hydrogels with integrated NO-releasing behavior show great potential for treating type I diabetic wounds.

Vancomycin coupled chitosan/PEO nanofibrous scaffold with the desired antibacterial activity as a potential for biomedical application

This study aims to evaluate the Vancomycin (VCM) combination with Chitosan (CS)/ Polyethylene oxide (PEO) nanofibers’ intrinsic antibacterial properties causing a synergistic effect against possible serious bacterial infections (PSBI). VCM/CS nanofiber scaffold was fabricated using the electrospinning method. Characterizations are performed by Fourier transform infrared (FT-IR) to examine the functional groups of each compound, scanning electron microscopy (SEM), and transient electron microscopy (TEM) to evaluate nanofiber diameter and structure. Antibacterial activities of the nanofibrous scaffold were assessed against bacterial strains, including standard Staphylococcus aureus ( S. aureus), VCM-sensitive Enterococcus (VSE), methicillin-resistant S. aureus (MRSA), VCM-resistant Enterococcus (VRE), and Streptococcus group A by microdilution broth methods. The FT-IR, SEM, and TEM examination results confirm the CS/PEO nanofiber scaffold fabrication. The antibacterial examination results showed no significant difference between the minimum inhibitory concentration (MIC) values of VCM and with MIC of VCM/CS nanofibers. Still, there were significant differences between the MIC of CS and VCM/CS nanofibers in S. aureus, but this is not more significant than VCM. This study illustrated that VCM coupled to CS nanofibers had acceptable antibacterial activity against the Gram-positive bacterium. This work motivated researchers’ insight into nanostructures’ potential accompanied by antibacterial polymer and antibiotics synergistic effects against PSBI.

Promising Materials in the Fight against Healthcare-Associated Infections: Antibacterial Properties of Chitosan-Polyhedral Oligomeric Silsesquioxanes Hybrid Hydrogels.

New technologies and materials could help in this fight against healthcare-associated infections. As the majority of these infections are caused by antibiotic-resistant bacteria, the development of materials with intrinsic antibacterial properties is a promising field of research. We combined chitosan (CS), with antibacterial properties, with polyhedral oligomeric silsesquioxanes (POSS), a biocompatible polymer with physico-chemical, mechanical, and rheological properties, creating a hydrogel using cross-linking agent genipin. The antibacterial properties of CS and CS-POSS hydrogels were investigated against nosocomial Gram-positive and Gram-negative bacteria both in terms of membrane damage and surface charge variations, and finally, the anti-biofilm property was studied through confocal microscopy. Both materials showed a good antibacterial capacity against all analyzed strains, both in suspension, with % decreases between 36.36 and 73.58 for CS and 29.86 and 66.04 for CS-POSS, and in plates with % decreases between 55.29 and 78.32 and 17.00 and 53.99 for CS and CS-POSS, respectively. The treated strains compared to the baseline condition showed an important membrane damage, which also determined a variation of surface charges, and finally, for both hydrogels, a remarkable anti-biofilm property was highlighted. Our findings showed a possible future use of these biocompatible materials in the manufacture of medical and surgical devices with intrinsic antibacterial and anti-biofilm properties.

Photothermal/Photoacoustic Therapy Combined with Metal-Based Nanomaterials for the Treatment of Microbial Infections.

The increased spread and persistence of bacterial drug-resistant phenotypes remains a public health concern and has contributed significantly to the challenge of combating antibiotic resistance. Nanotechnology is considered an encouraging strategy in the fight against antibiotic-resistant bacterial infections; this new strategy should improve therapeutic efficacy and minimize side effects. Evidence has shown that various nanomaterials with antibacterial performance, such as metal-based nanoparticles (i.e., silver, gold, copper, and zinc oxide) have intrinsic antibacterial properties. These antibacterial agents, such as those made of metal oxides, carbon nanomaterials, and polymers, have been used not only to improve antibacterial efficacy but also to reduce bacterial drug resistance due to their interaction with bacteria and their photophysical properties. These nanostructures have been used as effective agents for photothermal therapy (PTT) and photodynamic therapy (PDT) to kill bacteria locally by heating or the controlled production of reactive oxygen species. Additionally, PTT or PDT therapies have also been combined with photoacoustic (PA) imaging to simultaneously improve treatment efficacy, safety, and accuracy. In this present review, we present, on the one hand, a summary of research highlighting the use of PTT-sensitive metallic nanomaterials for the treatment of bacterial and fungal infections, and, on the other hand, an overview of studies showing the PA-mediated theranostic functionality of metal-based nanomaterials.

A Facile Strategy to Construct Anti-Swelling, Antibacterial, and Antifogging Coatings for Protection of Medical Goggles.

During the COVID-19 (Corona Virus Disease 2019) pandemic, traditional medical goggles are not only easy to attach bacteria and viruses in long-term exposure, but easy to fogged up, which increases the risk of infection and affects productivity. Bacterial adhesion and fog can be significantly inhibited through the hydrogel coatings, owing to super hydrophilic properties. On the one hand, hydrogel coatings are easy to absorb water and swell in wet environment, resulting in reduced mechanical properties, even peeling off. On the other hand, the hydrogel coatings don't have intrinsic antibacterial properties, which still poses a potential risk of bacterial transmission. Herein, an anti-swelling and antibacterial hydrogel coating is synthesized by 2-hydroxyethyl methacrylate (HEMA), acrylamide (AM), dimethylaminoethyl acrylate bromoethane (IL-Br), and poly(sodium-p-styrenesulfonate) (PSS). Due to the self-driven entropy reduction effect of polycation and polyanion, an ion cross-linking network is formed, which endows the hydrogel coating with excellent antiswelling performance. Moreover, because of the synergistic effect of highly hydrated surfaces and the active bactericidal effect from quaternary ammonium cations, the hydrogel coating exhibits outstanding antifouling performances. This work develops a facile strategy to fabricate anti-swelling, antifouling, and antifogging hydrogel coatings for the protection of medical goggles, and also for biomedical and marine antifouling fields.

Treatment of Periodontal Infections, the Possible Role of Hydrogels as Antibiotic Drug-Delivery Systems

With the advancement of biomedical research into antimicrobial treatments for various diseases, the source and delivery of antibiotics have attracted attention. In periodontal diseases, antibiotics are integral in positive treatment outcomes; however, the use of antibiotics is with caution as the potential for the emergence of resistant strains is of concern. Over the years, conventional routes of drug administration have been proven to be effective for the treatment of PD, yet the problem of antibiotic resistance to conventional therapies continues to remain a setback in future treatments. Hydrogels fabricated from natural and synthetic polymers have been extensively applied in biomedical sciences for the delivery of potent biological compounds. These polymeric materials either have intrinsic antibacterial properties or serve as good carriers for the delivery of antibacterial agents. The biocompatibility, low toxicity and biodegradability of some hydrogels have favoured their consideration as prospective carriers for antibacterial drug delivery in PD. This article reviews PD and its antibiotic treatment options, the role of bacteria in PD and the potential of hydrogels as antibacterial agents and for antibiotic drug delivery in PD. Finally, potential challenges and future directions of hydrogels for use in PD treatment and diagnosis are also highlighted.

Synthesis and antimicrobial testing of 5-fluorouracil derivatives.

Antibiotic resistance has increased the demand for novel treatments against multidrug-resistant microorganisms. In the research literature, 5-fluorouracil (5-FU) was proposed as an alternative due to its intrinsic antibacterial property. However, given its toxicity profile at high doses, its use in antibacterial therapy is dubious. In the quest for improving the efficacy of 5-FU, the present study intends to synthesise 5-FU derivatives and assess their susceptibility and mechanism against pathogenic bacteria. It was found that the compounds having tri-hexylphosphonium substitution on both nitrogen groups of 5-FU (6a, 6b and 6c) had considerable activity against both Gram-positive and Gram-negative bacteria. Among the active compounds, those with an asymmetric linker group 6c were found to have higher antibacterial efficacy. However, no conclusive efflux inhibition activity was found. As elucidated by electron microscopy studies, these self-assembling active phosphonium-based 5-FU derivatives caused considerable septal damage and cytosolic alterations in Staphylococcus aureus cells. In Escherichia coli, these compounds triggered plasmolysis. Interestingly, the minimal inhibitory concentration (MIC) of the most potent 5-FU derivative 6c remained constant, regardless of the bacteria's resistance profile. Further analysis revealed that compound 6c generated significant alterations in membrane permeabilization and depolarization in S. aureus and E. coli cells at the MIC. Compound 6c was found to substantially impede bacterial motility, suggesting its importance in regulating bacterial pathogenicity. Additionally, the nonhaemolytic activity of 6c suggested that it could be a potential therapeutic option for treating multidrug-resistant bacterial infections.

Green Nanoformulations of Polyvinylpyrrolidone-Capped Metal Nanoparticles: A Study at the Hybrid Interface with Biomimetic Cell Membranes and In Vitro Cell Models.

Noble metal nanoparticles (NP) with intrinsic antiangiogenic, antibacterial, and anti-inflammatory properties have great potential as potent chemotherapeutics, due to their unique features, including plasmonic properties for application in photothermal therapy, and their capability to slow down the migration/invasion speed of cancer cells and then suppress metastasis. In this work, gold (Au), silver (Ag), and palladium (Pd) NP were synthesized by a green redox chemistry method with the reduction of the metal salt precursor with glucose in the presence of polyvinylpyrrolidone (PVP) as stabilizing and capping agent. The physicochemical properties of the PVP-capped NP were investigated by UV-visible (UV-vis) and attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopies, dynamic light scattering (DLS), and atomic force microscopy (AFM), to scrutinize the optical features and the interface between the metal surface and the capping polymer, the hydrodynamic size, and the morphology, respectively. Biophysical studies with model cell membranes were carried out by using laser scanning confocal microscopy (LSM) with fluorescence recovery after photobleaching (FRAP) and fluorescence resonance energy transfer (FRET) techniques. To this purpose, artificial cell membranes of supported lipid bilayers (SLBs) made with 1-palmitoyl-2-oleoyl-sn-glycerol-3-phosphocholine (POPC) dye-labeled with 7-nitro-2-1,3-benzoxadiazol-4-yl (NBD, FRET donor) and/or lissamine rhodamine B sulfonyl (Rh, FRET acceptor) were prepared. Proof-of-work in vitro cellular experiments were carried out with prostate cancer cells (PC-3 line) in terms of cytotoxicity, cell migration (wound scratch assay), NP cellular uptake, and cytoskeleton actin perturbation.

Shaping Silver Nanoparticles' Size through the Carrier Composition: Synthesis and Antimicrobial Activity.

The increasing resistance of bacteria to conventional antibiotics represents a severe global emergency for human health. The broad-spectrum antibacterial activity of silver has been known for a long time, and silver at the nanoscale shows enhanced antibacterial activity. This has prompted research into the development of silver-based nanomaterials for applications in clinical settings. In this work, the synthesis of three different silver nanoparticles (AgNPs) hybrids using both organic and inorganic supports with intrinsic antibacterial properties is described. The tuning of the AgNPs' shape and size according to the type of bioactive support was also investigated. Specifically, the commercially available sulfated cellulose nanocrystal (CNC), the salicylic acid functionalized reduced graphene oxide (rGO-SA), and the commercially available titanium dioxide (TiO2) were chosen as organic (CNC, rGO-SA) and inorganic (TiO2) supports. Then, the antimicrobial activity of the AgNP composites was assessed on clinically relevant multi-drug-resistant bacteria and the fungus Candida albicans. The results show how the formation of Ag nanoparticles on the selected supports provides the resulting composite materials with an effective antibacterial activity.