Fabrication of nano-decorated ZnO-fibrillar chitosan exhibiting a superior performance as a promising replacement for conventional ZnO

Coated composite paper with nano-chitosan/cinnamon essential oil-nanoemulsion containing grafted CNC@ZnO nanohybrid; synthesis, characterization and inhibitory activity on Escherichia coli biofilm developed on grey zucchini

This investigation aims to highlight the applicability of a potent eco-friendly developed composite film to combat the Escherichia coli biofilm formed in a model food system. ZnO nanoparticles (NPs) synthesized using green methods were anchored on the surface of cellulose nanocrystals (CNCs). Subsequently, nano-chitosan (NCh) solutions were used to disperse the synthesized nanoparticles and cinnamon essential oil (CEO). These solutions, containing various concentrations of CNC@ZnO NPs and CEO, were sequentially coated onto cellulosic papers to inhibit Escherichia coli biofilms on grey zucchini slices. Six films were developed, and Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy, biodegradation, and mechanical properties were assessed. The film containing 5 % nano-emulsified CEO + 3 % dispersed CNC@ZnO nano-hybrid in an NCh solution was selected for further testing since it exhibited the largest zone of inhibition (34.32 mm) against E. coli and the highest anti-biofilm activity on biofilms developed on glass surfaces. The efficacy of the film against biofilms on zucchini surfaces was temperature-dependent. During 60 h, the selected film resulted in log reductions of approximately 4.5 logs, 2.85 logs, and 1.57 logs at 10 °C, 25 °C, and 37 °C, respectively. Applying the selected film onto zucchini surfaces containing biofilm structures leads to the disappearance of the distinctive three-dimensional biofilm framework. This innovative anti-biofilm film offers considerable potential in combatting biofilm issues on food surfaces. The film also preserved the sensory quality of zucchini evaluated for up to 60 days.

Multifunctional Gold-Silver-Carbon Quantum Dots Nano-Hybrid Composite: Advancing Antibacterial Wound Healing and Cell Proliferation

The urgent need for innovative materials that effectively eliminate bacteria while promoting cell growth to accelerate wound healing has led to the exploration of new options, as current antimicrobial nanoparticles often exhibit high cytotoxicity, which hinders wound closure. In this study, a nano-hybrid composite, named gold-silver-carbon quantum dots (AuAg-CDs), was prepared by embedding gold and silver nanoclusters into carbon dots. The AuAg-CDs nano-hybrid composite demonstrates remarkable biocompatibility, displays potent antibacterial activity, and possesses a unique capability to promote cell proliferation. By physically disrupting bacterial membranes and promoting mammalian cell proliferation, this composite emerges as a highly promising material for wound healing applications. The underlying mechanism of the multifunctional AuAg-CDs was investigated through comprehensive analyses encompassing cell morphology, bacterial membrane potential, levels of reactive oxygen species (ROS), and adenosine triphosphate (ATP) production in both bacterial and mammalian cells. Additionally, AuAg-CDs were incorporated into alginate to create a hydrogel wound dressing, which underwent evaluation using animal models. The results underscore the remarkable potential of the AuAg-CDs wound dressing in facilitating the proliferation of wound fibroblasts and combating bacterial infections. The significance of designing multifunctional nanomaterials to address the challenges associated with pathogenic bacterial infections and regenerative medicine is highlighted by this study, paving the way for future advancements in these fields.

Bringing resistance modulation to methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant enterococci (VRE) strains using a quaternary ammonium compound coupled with zinc oxide nanoparticles

Nowadays, there are concerns about the inadequacy of new antimicrobials and the rise of antimicrobial resistance. Hence, novel antibacterial agents need to be discovered. In this respect, the use of nanoparticles (NPs) seems promising. Zinc oxide nanoparticles (ZnONPs) are functional and inexpensive NPs that possess antimicrobial characteristics, stability, microbial selectivity, and an easy manufacturing procedure. Imidazolium is one of the quaternary ammonium compounds (QACs) frequently employed as antimicrobial materials in industrial and clinical fields. The present study successfully employed imidazolium to couple with ZnONPs to improve their antimicrobial properties. The antimicrobial activities of ZnONPs doped with imidazolium (IM@ZnONPs) compared to ZnONPs and zinc (Zn) ions against some pathogen microorganism species including Streptococcus aureus (S. aureus), Enterococcus faecalis (E. faecalis), methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant enterococci (VRE), and Candida albicans (C. albicans) were evaluated by the microdilution method. The minimum inhibitory concentration (MIC) results revealed that the antimicrobial activities of Zn ions, ZnONPs, and IM@ZnONPs were concentration-dependent. Moreover, we found that the nanoparticulate forms of Zn had considerably stronger antibacterial activities, particularly against VRE and MRSA, compared to Zn ions which failed to restrain the microbial strains at the tested microdilutions of this experiment (MIC: ≥512 µg/mL). Interestingly, the incorporation of imidazolium into ZnONPs resulted in significant inhibition of microbial growth in antimicrobial-resistant pathogens at low concentrations (MIC: 32 µg/mL) and effectively improved the monodispersity of the final coated NPs in terms of size and morphology. To sum up, IM@ZnONPs can be a favorable substitute for conventional antimicrobial agents to combat antimicrobial resistance in many fields, including pharmaceuticals, dental materials, and cosmetic products.

A step forward to overcome the cytotoxicity of graphene oxide through decoration with tragacanth gum polysaccharide

Hybridization of nanomaterials (NMs) with natural polymers is one of the best techniques to promote their exciting properties. In this way, the main objective of this work was to investigate the efficiency of decoration of the graphene oxide (GO) nano-sheets with tragacanth gum (TG) polysaccharide. To aim this, different approaches were used (with and without ultrasonic treatment) and various tests (XRD, FTIR, Raman, UV-Vis, DLS, Zeta potential, contact angle, AFM, FE-SEM, TEM, and MTT assay) were conducted. Test results indicated that the nano-hybrids were successfully synthesized. Furthermore, our findings represented that, the TG hybridized GO (TG-GO) appreciably enhanced the biocompatibility of GO. Moreover, it was demonstrated that the ultrasonic treatment of TG solution put a remarkable impact on the microstructure, wettability, and also surface charge characteristic of fabricated nano-hybrids and consequently improved the biocompatibility against L929-fibroblast cells.

Synthesis and Characterization of Green ZnO@polynaniline/Bentonite Tripartite Structure (G.Zn@PN/BE) as Adsorbent for As (V) Ions: Integration, Steric, and Energetic Properties

A green ZnO@polynaniline/bentonite composite (G.Zn@PN/BE) was synthesized as an enhanced adsorbent for As (V) ions. Its adsorption properties were assessed in comparison with the integrated components of bentonite (BE) and polyaniline/bentonite (PN/BE) composites. The G.Zn@PN/BE composite achieved an As (V) retention capacity (213 mg/g) higher than BE (72.7 mg/g) and PN/BE (119.8 mg/g). The enhanced capacity of G.Zn@PN/BE was studied using classic (Langmuir) and advanced equilibrium (monolayer model of one energy) models. Considering the steric properties, the structure of G.Zn@PN/BE demonstrated a higher density of active sites (Nm = 109.8 (20 °C), 108.9 (30 °C), and 67.8 mg/g (40 °C)) than BE and PN/BE. This declared the effect of the integration process in inducing the retention capacity by increasing the quantities of the active sites. The number of adsorbed As (V) ions per site (1.76 up to 2.13) signifies the retention of two or three ions per site by a multi-ionic mechanism. The adsorption energies (from -3.07 to -3.26 kJ/mol) suggested physical retention mechanisms (hydrogen bonding and dipole bonding forces). The adsorption energy, internal energy, and free enthalpy reflected the exothermic, feasible, and spontaneous nature of the retention process. The structure is of significant As (V) uptake capacity in the existence of competitive anions or metal ions.

Development of tannin-bridged cerium oxide microcubes-chitosan cryogel as a multifunctional wound dressing

Efficient resolution of oxidative stress, inflammation, and bacterial infections is crucial for wound healing. To surmount these problems, tannic acid (TA)-bridged CeO₂ microcubes and chitosan (CS) (CS-TA@CeO₂) cryogel was fabricated through hydrogen bonding interactions as a multifunctional wound dressing. Successful introduction and uniform incorporation TA@CeO₂ microtubules enter the CS network. Thus-obtained CS-TA@CeO₂ cryogels displayed a suitable porous structure and swelling rate. Cryogels has excellent tissue adhesion, blood cell coagulation and hemostasis, anti-infection, and cell recruitment functions. In addition, the cryogel also showed good antibacterial activity against gram-positive bacteria and gram-negative bacteria. Based on the in vivo study of the multifunctional mixed cryogels, it promotes fibroblasts' adhesion and proliferation and significantly improves cell proliferation and tissue remodelling in wound beds. Furthermore, the chronic wound healing process in infected full-thickness skin defect models showed that cryogels significantly enhanced angiogenesis, collagen deposition and granulation tissue formation by providing a large amount of antioxidant activity. Therefore, this multifunctional mixed cryogels has potential clinical application value.

Poly (vinyl alcohol)/chitosan/polyethylene glycol-assembled graphene oxide bio-nanocomposites as a prosperous candidate for biomedical applications and drug/food packaging industry

The graphene oxide (GO) nanoplates and polyethylene glycol-decorated GO (GO-PEG nano-hybrid) were synthesized and characterized by FTIR, Raman, XRD, AFM, FE-SEM-EDAX and MTT assay. Obtained results confirmed the graphite oxidation and also assembly of PEG upon GO plates. The MTT assay indicated that GO-PEG nanohybrid enhanced biocompatibility to cells compared to the GO. The GO-PEG nanohybrid was introduced to the polyvinyl alcohol/chitosan carbohydrate (PVA/CS) blends. The bio-nanocomposite were prepared by simple casting method. The GO-PEG nanohybrids demonstrated a significant role in improving thermal, mechanical and antibacterial properties. Accordingly, bio-nanocomposites containing modified GO (PVA/CS/GO-PEG) exhibited higher glass transition temperature (Tg), Young's modulus, tensile strength, elongation at break and antibacterial properties than nanocomposites containing pure GO (PVA/CS/GO). The biodegradation outcomes indicated that the highest weight loss and degradability is related to the bio-nanocomposite containing modified GO (PVA/CS/GO-PEG), which was also confirmed by FE-SEM micrographs. Therefore, PVA/CS/GO-PEG bio-nanocomposites can be a suitable candidate for biomedical applications (tissue engineering, wound dressing) and food-drug packaging industry.