Bioinspired Heteromultivalent Chitosan-α-Fe₂O₃/Gadofullerene Hybrid Composite for Enhanced Antibiotic-Resistant Bacterial Pneumonia

Design of an imaging magnetic microsphere based on photopolymerization for magnetic hyperthermia in tumor therapy

Magnetic hyperthermia therapy has been widely used in the nonsurgical treatment of patients with advanced stage cancers that cannot be treated by surgery. It is minimally invasive, precise, and highly efficient and has a good curative effect. In this paper, a magnetic microsphere with Fe3O4 was prepared for thermal therapy and imaging based on a photoinitiated suspension polymerization method from biallelic monomers. The preparation method clearly minimized the degradative chain transfer of allyl polymerization reactions. The microspheres were characterized by microscope observation, spectral analysis, thermal analysis, and magnetic testing. The magnetothermal effect was detected by an infrared thermal imager in vitro and in vivo under a high-frequency alternating magnetic field (AMF). The antitumor effect was verified by testing the viability of H22 cells and observing a tumor-bearing mouse model under high-frequency AMF. Biocompatibility was evaluated by cell viability assay, tissue section observation, and blood biochemical analysis. The imaging capacity was tested by X-ray, MRI, and CT imaging experiments. The results show that the product has good dispersibility, thermal stability, superparamagnetism, and biocompatibility. Under the action of an AMF, the magnetic hyperthermia effect in tumor-bearing mice was better, and an antitumor effect could be achieved.

Magnetic Nanoparticles: Current Advances in Nanomedicine, Drug Delivery and MRI

Magnetic nanoparticles (MNPs) have evolved tremendously during recent years, in part due to the rapid expansion of nanotechnology and to their active magnetic core with a high surface-to-volume ratio, while their surface functionalization opened the door to a plethora of drug, gene and bioactive molecule immobilization. Taming the high reactivity of the magnetic core was achieved by various functionalization techniques, producing MNPs tailored for the diagnosis and treatment of cardiovascular or neurological disease, tumors and cancer. Superparamagnetic iron oxide nanoparticles (SPIONs) are established at the core of drug-delivery systems and could act as efficient agents for MFH (magnetic fluid hyperthermia). Depending on the functionalization molecule and intrinsic morphological features, MNPs now cover a broad scope which the current review aims to overview. Considering the exponential expansion of the field, the current review will be limited to roughly the past three years.

Metformin-Loaded Alginate Nanoparticles Inhibits Mouse Atherosclerosis by Regulating Macrophage Differentiation by Activating the Adenosine Monophosphate-Activated Protein Kinase/Signal Transducer and Activator of Transcription 3 Pathway

Objective: By modulating macrophage phenotype and the adenylate-activated protein kinase/signal transducer and activator of transcription 3 (STAT3) signaling pathway, metformin-loaded alginate nanoparticles may prevent atherosclerosis (As). Methods: Flow cytometry was used to determine the percentage of macrophages with distinct phenotypes (CD86 and CD206). Analysis of protein expression levels of iNOS, arginase 1, AMPK, pAMPK, STAT3 and phosphorylated STAT3 were performed by Western Blot. To confirm the in vitro findings, ApoE−/− mice were employed. Results: AMPK activity and the fraction of M2 macrophages dramatically increased in cells treated with Met, but STAT3 activity was considerably reduced. It was also shown that the Met group had much shorter aortas and lower levels of lipid deposition than that of the control group; also, the fraction of M1 macrophages in the lipid plaques of the animals treated with Met was dramatically reduced by using immunofluorescence labeling. There was a considerable increase in AMPK activity in the Met group, but STAT3 activity was dramatically lowered. Conclusion: According to the results of this study, STAT3 activity is regulated by activation of AMPK and macrophage development in plaques is prevented in mice by metformin-loaded alginate nanoparticles.

Antibacterial Properties of Ag-Cu Alloy Nanoparticles Against Multidrug-Resistant Pseudomonas aeruginosa Through Inhibition of Quorum Sensing Pathway and Virulence-Related Genes

Objective: To evaluate the application of Ag-Cu NPs as quorum sensing (QS) inhibitors and attenuate virulence expression to overcome the global crisis of multidrug-resistant (MDR) P. aeruginosa. Methods: Ag-Cu NPs were synthesized by co-reduction of silver-nitrate and copper-nitrate (Ag:Cu = 1:1 0.75 μM). In this cross-sectional study, a total of eighty clinical strains of P. aeruginosa were collected from patients with burns. The antibacterial and resistance pattern of the clinical isolated was determined using the microdilution and Kirby Bauer disk methods. The effect of sub-MIC of Ag-Cu NPs on the expression of lasI, exoS and toxA in five clinical isolates of imipenem-resistant P. aeruginosa was performed using qRT-PCR. Results: The characterization methods confirm the formation of the Ag-Cu alloy NPs with agglomerated spherical morphology and particle sizes of about 30-40 nm. We observed that the MIC and MBC of Ag-Cu alloy NPs against MDR P. aeruginosa was found to be 2.5 and 5 μg ml^-1, respectively. The effects of a sub-inhibitory concentration of Ag-Cu NPs on MDR P. aeruginosa QS and virulence-related genes showed that the expression level of QS regulatory and virulence genes significantly decreased in both MDR P. aeruginosa and reference strain under Ag-Cu sub-MIC treatment. Conclusion: Ag-Cu NPs could be potentially used as a promising QS inhibitor and anti-virulence compound against P. aeruginosa.

A biomimetic hierarchical small intestinal submucosa-chitosan sponge/chitosan hydrogel scaffold with a micro/nano structure for dural repair

The dura mater is an essential barrier to protect the brain tissue and the dural defects caused by accidents can lead to serious complications. Various materials have been applied to dural repair, but it remains a challenge to perfectly match the structure and properties of the natural dura mater. Small intestinal submucosa has been developed for dural repair because of its excellent biocompatibility and biological activity, but its application is tremendously limited by the rapid degradation rate. Chitosan has also been broadly investigated in tissue repair, but the traditional chitosan hydrogels exhibit poor mechanical properties. A nanofiber chitosan hydrogel can be constructed based on an alkaline solvent, which is equipped with surprisingly high strength. Therefore, based on the bilayer structure of the natural dura mater, a biomimetic hierarchical small intestinal submucosa-chitosan sponge/chitosan hydrogel scaffold with a micro/nano structure was fabricated, which possessed a microporous structure in the upper sponge and a nanofiber structure in the lower hydrogel. The degradation rate was remarkably reduced compared with that of the small intestinal submucosa in the enzymatic degradation experiment in vitro. Meanwhile, the chitosan nanofibers brought high mechanical strength to the bilayer scaffold. Moreover, the hierarchical micro/nano structure and the active factors in the small intestinal submucosa have a fantastic effect on promoting the proliferation of fibroblasts and vascular endothelial cells. The bilayer scaffold showed good histocompatibility in the experiment of in vitro subcutaneous implantation in rats. Thus, the biomimetic hierarchical small intestinal submucosa-chitosan sponge/chitosan hydrogel scaffold with micro/nano structure simulates the structure of the natural dura mater and possesses properties with excellent performance, which has high practical value for dural repair.