Biocompatible polyurethane/thiacalix[4]arenes functionalized Fe3O4 magnetic nanocomposites: Synthesis and properties

Biological Effects, Applications and Design Strategies of Medical Polyurethanes Modified by Nanomaterials

Polyurethane (PU) has wide application and popularity as medical apparatus due to its unique structural properties relationship. However, there are still some problems with medical PUs, such as a lack of functionality, insufficient long-term implantation safety, undesired stability, etc. With the rapid development of nanotechnology, the nanomodification of medical PU provides new solutions to these clinical problems. The introduction of nanomaterials could optimize the biocompatibility, antibacterial effect, mechanical strength, and degradation of PUs via blending or surface modification, therefore expanding the application range of medical PUs. This review summarizes the current applications of nano-modified medical PUs in diverse fields. Furthermore, the underlying mechanisms in efficiency optimization are analyzed in terms of the enhanced biological and mechanical properties critical for medical use. We also conclude the preparation schemes and related parameters of nano-modified medical PUs, with discussions about the limitations and prospects. This review indicates the current status of nano-modified medical PUs and contributes to inspiring novel and appropriate designing of PUs for desired clinical requirements.

Antibacterial Host-Guest Intercalated LDH-Adorned Polyurethane for Accelerated Dermal Wound Healing

Curcumin has a limited clinical application because of its extremely poor accessibility. In the present study, improved curcumin bioavailability within a castor oil polyurethane/layered double hydroxide (LDH) wound cover was achieved by preparing a curcumin p-sulfonic acid calix[4]arene (SC4A) inclusion complex. Then, it was utilized to intercalate MgAl-layered double hydroxide (MgAl-LDH) nanosheets. The incorporation of the nanostructure into a PU/Cur-SC4A-LDH film provided bacteria-killing performance against both Gram-positive Staphylococcus aureus and Gram-negative Escherichia coli bacteria. This finding is due to an increase in curcumin bioavailability in the PU matrix. Furthermore, all PU nanocomposites exhibited appropriate cytocompatibility based on an MTT assay. Mainly, the proliferation of L929 fibroblast cells in contact with the PU/Cur-SC4A-LDH sample was significantly further enhanced than that for other nanocomposites within 7 days. This observation can be related to the better availability of curcumin on the film's surface, which causes an improvement in the proliferation rate of cells. Regarding the histological results, the hematoxylin and eosin (H&E) images showed faster epidermal layer formation and a larger quantity of matured hair follicles for PU/Cur-SC4A-LDH-healed wounds in comparison with those for the negative control over a period of 28 days. Thus, this practical healing ability of the PU/Cur-SC4A-LDH nanocomposite makes it a promising candidate as a wound dressing film.

Nanomagnetic macrocyclic Schiff-base-Mn(ii) complex: an efficient heterogeneous catalyst for click approach synthesis of novel β-substitued-1,2,3-triazoles

In the present work, a novel symmetrical 15-membered macrocyclic Schiff base complex of manganese was prepared using the reaction of the synthetic 2,6-diacetylpyridine functionalized Fe₃O₄ MNPs with 2,2-(piperazine-1,4-diyl)dianiline and Mn(ii) bromide salt via a template approach. The resulting [Fe₃O₄@PAM-Schiff-base-Mn][ClO₄] heterogenized complex was characterized using FT-IR, XRD, BET, TGA, EDX, Xray-mapping, SEM, TEM and VSM analysis. To demonstrate proof of concept, Huisgen 1,3-dipolar cycloaddition synthesis of 1,2,3-triazoles was selected to evaluate the activity and reusability of the catalyst. The ethanol as a green solvent proved to be an excellent reaction medium for this synthesis. Yields of up to 100% were obtained in some cases. Significantly, as demonstrated, [Fe₃O₄@PAM-Schiff-base-Mn][ClO₄] catalyst was recycled for 8 cycles without losing catalytic activity under the optimized reaction conditions. The hot filtration and ICP-OES tests ratified that there was no leaching of metal during the catalytic reaction, indicating the heterogeneous manner of the catalyst.

Novel electrospun conduit based on polyurethane/collagen enhanced by nanobioglass for peripheral nerve tissue engineering

Peripheral nerve injury can significantly affect the daily life of individuals with impaired nerve function and permanent nerve deformity. One of the most common treatments is autograft transplantation. Tissue engineering is one of the efficient methods to regenerate injured nerves using scaffolds, cells, and growth factors. Conduits, which are produced by a variety of techniques, could be used as an alternative treatment for patients with damaged nerves. The electrospinning technique is one of the most important and widely used methods for generating nanofiber conduits from biocompatible polymers. In this study, using the electrospinning method, three different conduits, including polyurethane (PU), polyurethane/collagen (PU/C), and a new conduit based on polyurethane + collagen + nanobioglass (PU/C/NBG), were prepared. The characteristics of these three types of conduits were evaluated by SEM, XRD, and various experiments, including porosity, degradation, contact angle, DMTA, FTIR, MTT, and DAPI staining. The results of MTT and DAPI assays revealed the safety of conduits and proper cell attachment. Overall, the results obtained from various experiments showed that the novel PU/C/NBG conduit has better mechanical properties in terms of porosity, hydrophilicity, and biocompatibility in comparison with PU and PU/C conduits and could be a suitable candidate for peripheral nerve regeneration and axonal growth due to its repair potential.

Magnetic solid-phase extraction based on zirconium-based metal-organic frameworks for simultaneous enantiomeric determination of eight chiral pesticides in water and fruit juices

A novel multi-residue method, magnetic solid-phase extraction combined with LC-MS/MS, was proposed for simultaneous enantiomeric determination of eight chiral pesticides in water and fruit juices. Fe₃O₄@C@UiO-66 was firstly used to extract and enrich pesticides, showing excellent adsorption capacity, which was proved by adsorption kinetic and thermodynamic experiments. Multiple extraction parameters were optimized by Plackett-Burman and Box-Behnken design. Under optimized conditions, good linearity (1.0-200 ng L^-1, R² ≥ 0.9953) for all analytes, detection limits (0.10 to 0.35 ng L^-1), quantitation limits (0.35 to 1.00 ng L^-1), recoveries (83.68-95.99%), and precision (intra-day RSD ≤ 7.06%, inter-day RSD ≤ 9.40%) were obtained, meeting the requirements of pesticides residues analysis. It is worth mentioning that eight chiral pesticides can be separated quickly within 19 min. The above results indicate that the proposed method with satisfactory sensitivity and accuracy has the potential for routine analysis of chiral pesticide residues in aqueous samples.

The sandwich-like structures of polydopamine and 8-hydroxyquinoline coated graphene oxide for excellent corrosion resistance of epoxy coatings

A novel sandwich-like structure material was exploited for the fabrication of an effective corrosion resistance system. An environmentally friendly composite material was synthesized by installing 8-hydroxyquinoline (8-HQ) on the surface of graphene oxide (GO). In order to prevent leakage of corrosion inhibitor 8-HQ, GO/8-HQ was modified by polydopamine (PDA), denoted as GO/8-HQ/PDA. A sandwich-like structure (GO/8-HQ/PDA) enables long-term stable storage of corrosion inhibitor in the protective matrix. Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) were utilized to verify the sandwich-like structure of GO/8-HQ/PDA. The electrochemical tests in a 3.5 wt% NaCl solution showed that the addition of well-dispersed GO/8-HQ/PDA into epoxy system (GO/8-HQ/PDA-EP) remarkably improved corrosion protection of AZ31b magnesium alloy compared with pure epoxy (EP) coating. The sandwich structure protects the activity and structural integrity of the corrosion inhibitor (8-HQ). The corrosion inhibitor (8-HQ) of the GO/8-HQ/PDA sandwich structure cuts off the ion exchange between the metal alloy and the electrolyte solution, which hinders the electrochemical corrosion of the metal. A possible corrosion resistance mechanism of GO/8-HQ/PDA is fully discussed. This study provides feasibilities for the immobilization of corrosion inhibitors on the metal surface.

Preparation and characterization of a new hydrophilic and biocompatible magnetic polypropylene carrier used in wastewater treatment

This paper employed a blending method to prepare a new hydrophilic and biocompatible magnetic polypropylene carrier (HBMPC) and pure polypropylene carrier (PPC). Mechanical strength, magnetic induction on surface, microstructure, hydrophilicity and biocompatibility of HBMPC were measured, characterized and investigated respectively. The results showed that mechanical strength of PPC and HBMPC was not much different; magnetic induction on the surface of HBMPC was 4-6 mT; HBMPC had relatively large surface roughness and specific surface; average water content of PPC and HBMPC was 47.1% and 64.7%, respectively; contact angle of PPC and HBMPC was 88.7° and 58.5°, respectively; adsorption capacity of HBMPC and PPC to microorganism was 5.40E + 05 and 5.70E + 04 cfu (g·h)^-1, respectively. It took about 15 days for PPC to succeed in biofilm culturing while it took only 12 days for HBMPC. COD and [Formula: see text] removal efficiencies of PPC and HBMPC on the 15th day of biofilm formation were 80.5%, 90.5%, 63.7% and 85.4%, respectively; and growth status of microorganism adhering to the surface of HBMPC was better than that of PPC, biomass on single HBMPC and PPC after succeeded in biofilm culturing was 43.9 and 27.4 mg, respectively. All of these indicated that HBMPC had excellent hydrophilicity and biocompatibility.

Synthesis and characterization of optically active magnetic PAI/Fe3O4 nanocomposites

This work presents the preparation and characterization of hybrid organic-inorganic optically active poly(amide-imide)/nano-Fe₃O₄ composites with different amount of modified Fe₃O₄ nanoparticles as new nanocomposites by ultrasonic irradiation and characterized by Fourier transform infrared spectra, X-ray diffraction, scanning electron microscopy (SEM), thermogravimetric analysis and vibrating sample magnetometry. The surface of Fe₃O₄ nanoparticles was modified with 3-aminopropyltriethoxyl silane because of the homogeneous distribution of nano-Fe₃O₄ in polymer matrix, which the SEM results confirmed that the Fe₃O₄ nanoparticles were dispersed uniformly in polymer matrix. Furthermore, as compared with pure polymer, thermogravimetric analysis data indicated an improvement of thermal stability of nanocomposites.