Vancomycin and nisin-modified magnetic Fe3O4@SiO2 nanostructures coated with chitosan to enhance antibacterial efficiency against methicillin resistant Staphylococcus aureus (MRSA) infection in a murine superficial wound model

BACKGROUND

The objective of this research was to prepare some Fe3O4@SiO2@Chitosan (CS) magnetic nanocomposites coupled with nisin, and vancomycin to evaluate their antibacterial efficacy under both in vitro and in vivo against the methicillin-resistant Staphylococcus. aureus (MRSA).

METHODS

In this survey, the Fe3O4@SiO2 magnetic nanoparticles (MNPs) were constructed as a core and covered the surface of MNPs via crosslinking CS by glutaraldehyde as a shell, then functionalized with vancomycin and nisin to enhance the inhibitory effects of nanoparticles (NPs). X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), field emission scanning electron microscope (FE-SEM), vibrating sample magnetometer (VSM), and dynamic light scattering (DLS) techniques were then used to describe the nanostructures.

RESULTS

Based on the XRD, and FE-SEM findings, the average size of the modified magnetic nanomaterials were estimated to be around 22-35 nm, and 34-47 nm, respectively. The vancomycin was conjugated in three polymer-drug ratios; 1:1, 2:1 and 3:1, with the percentages of 45.52%, 35.68%, and 24.4%, respectively. The polymer/drug ratio of 1:1 exhibited the slowest release rate of vancomycin from the Fe3O4@SiO2@CS-VANCO nanocomposites during 24 h, which was selected to examine their antimicrobial effects under in vivo conditions. The nisin was grafted onto the nanocomposites at around 73.2-87.2%. All the compounds resulted in a marked reduction in the bacterial burden (P-value < 0.05).

CONCLUSION

The vancomycin-functionalized nanocomposites exhibited to be more efficient in eradicating the bacterial cells both in vitro and in vivo. These findings introduce a novel bacteriocin-metallic nanocomposite that can suppress the normal bacterial function on demand for the treatment of MRSA skin infections.

Design of Bio-Graphene-Based Multifunctional Nanocomposites Exhibits Intracellular Drug Delivery in Cervical Cancer Treatment

The advent of bio-nanotechnology has revolutionized nanodrug delivery by improving drug efficacy and safety. Nevertheless, acceptable carriers for therapeutic molecules are one of the most difficult challenges in drug delivery. Graphene material-based (GMB) and polymer-based drug-loaded nanocarriers have both demonstrated clinical advantages in delivering drugs of interest in vitro/in vivo. Cisplatin (CDDP) is an inorganic chemotherapeutic drug that is commonly used to treat a variety of cancers. However, its clinical use is associated with drug resistance and few side effects, which reduces its antitumor effects. Therefore, we developed a CDDP-loaded chitosan-functionalized graphene oxide nanocomposite (CDDP@CS-GO NC)-based nanodrug delivery system (NDDS). Flow cytometry and confocal imaging show that the CDDP@CS-GO NCs lead to significantly increased intracellular drug accumulation in tumor cells. Cancer cells take up the nanocomposite via endocytosis and can generate intracellular reactive oxygen species (ROS) to increase mitochondrial membrane potential loss (Δψm) and enable cytochrome-c release, followed by the dysregulation of Bcl-2 into the cytosol and activation of caspase-3 to induce cancer cell apoptosis. In vitro experiments demonstrated the excellent cancer therapeutic effect with few side effects of the carriers. CDDP@CS-GO NCs are expected to play an important role in responsive NDDSs for cancer therapy.

Determination of mechanical properties of two-phase and hybrid nanocomposites: experimental determination and multiscale modeling

In this paper, the effects of filler content and the use of hybrid nanofillers on agglomeration and nanocomposite mechanical properties such as elastic moduli, ultimate strength and elongation to failure are investigated experimentally. In addition, thermoset epoxy-based two-phase and hybrid nanocomposites are simulated using multiscale modeling techniques. First, molecular dynamics simulation is carried out at nanoscale considering the interphase. Next, finite element method and micromechanical modeling are used for micro and macro scale modeling of nanocomposites. Nanocomposite samples containing carbon nanotubes, graphene nanoplatelets, and hybrid nanofillers with different filler contents are prepared and are tested. Also, field emission scanning electron microscopy is used to take micrographs from samples’ fracture surfaces. The results indicate that in two-phase nanocomposites, elastic modulus and ultimate strength increase while nanocomposite elongation to failure decreases with reinforcement weight fraction. In addition, nanofiller agglomeration occurred at high nanofiller contents especially higher than 0.75 wt% in the two-phase nanocomposites. Nanofiller agglomeration was observed to be much lower in the hybrid nanocomposite samples. Therefore, using hybrid nanofillers delays/prevents agglomeration and improves mechanical properties of nanocomposite at the same total filler content.