Study of engineered low-modulus Mg/PLLA composites as potential orthopaedic implants: An in vitro and in vivo study

Design of Light-Driven Biocompatible and Biodegradable Microrobots Containing Mg-Based Metallic Glass Nanowires

Light-driven microrobots capable of moving rapidly on water surfaces in response to external stimuli are widely used in a variety of fields, such as drug delivery, remote sampling, and biosensors. However, most light-driven microrobots use graphene and carbon nanotubes as photothermal materials, resulting in poor biocompatibility and degradability, which greatly limits their practical bioapplications. To address this challenge, a composition and microstructure design strategy with excellent photothermal properties suitable for the fabrication of light-driven microrobots was proposed in this work. The Mg-based metallic glass nanowires (Mg-MGNWs) were embedded with polyhydroxyalkanoates (PHA) to fabricate biocompatible and degradable microrobots with excellent photothermal effect and complex shapes. Consequently, the microrobot can be precisely driven by a near-infrared laser to achieve high efficiency and remote manipulation on the water surface for a long period of time, with a velocity of 9.91 mm/s at a power density of 2.0 W/cm2. Due to the Marangoni effect, programmable and complex motions of the microrobot such as linear, clockwise, counterclockwise, and obstacle avoidance motions can be achieved. The biocompatible and degradable microrobot fabrication strategy could have great potential in the fields of environmental detection, targeted drug delivery, disease diagnosis, and detection.

Preparation of fully bio-based multilayers composed of heparin-like carboxymethylcellulose sodium and chitosan to functionalize poly (l-lactic acid) film for cardiovascular implant applications

In this study, heparin-like polysaccharides were successfully produced by sulfation of carboxymethylcellulose sodium, then a fully biobased bilayer composed of sulfated carboxymethylcellulose sodium (SCMC) and chitosan (CS) was composited on the surface of Poly (L-lactic acid) (PLA) through layer-by-layer (LBL) assembly for the potential blood-contact application such as bioresorbable vascular scaffold. The preliminary structure and bioactivity of SCMC with different degree of sulfation were investigated, and the SCMC with best performance was selected. The surface chemical compositions, morphologies and wettability of SCMC/CS multilayer-modified PLA films were researched by X-ray photoelectron spectrometer, scanning electron microscopy and water contact angle meter. A series of anticoagulation tests of SCMC/CS multilayer-modified PLA films were performed. In term of (SCMC/CS)₁₅ multilayer-modified PLA film, the protein adsorption and plate adhesion decreased by 44.6 % and 71.5 %, respectively, the activated partial thromboplastin time prolonged by 11.9 times and thrombin time exceed 300 s, the contact activation and hemolysis rate significantly reduced compared with unmodified PLA film. Besides, this modified PLA films performed good cytocompatibility to L929 fibroblast cells, excellent anti-inflammatory and antibacterial abilities. In conclusion, the multifunctional SCMC/CS multilayer-modified PLA films with hemocompatibility, cytocompatibility, anti-inflammatory and antibacterial properties may have promising potential in future clinical applications.

Surface Modification of WE43 Magnesium Alloys with Dopamine Hydrochloride Modified GelMA Coatings

As biodegradable medical implants, magnesium alloys have attracted great concerns due to their desirable biological and mechanical performances. Nevertheless, the overfast degradation rate of magnesium alloys makes it difficult to make full use of their potential in medical sciences. Therefore, it is a hot issue to control the degradation rate and functionalize the magnesium alloys via surface modifications. Herein, methacrylate gelatin (GelMA) hydrogel was adopted as coatings on the surface of WE43 magnesium alloys to control the degradation behaviors of magnesium alloys. Inspired by mussels, dopamine (DOPA) hydrochloride was adopted to modify GelMA to further functionalize the coatings. The compositions, swelling properties, degradation behaviors, and morphologies of samples were characterized by UV-Vis spectrophotometer, nuclear magnetic resonance (NMR), Fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM), and immersion test. It was shown that GelMA-DOPA composites could be obtained and the swelling and degradation behaviors of magnesium alloys could be controlled by adjusting the compositions of GelMA and DOPA. Furthermore, the GelMA-DOPA hydrogel coatings can be tightly bonded to the Mg alloys.

The effect of composite PHB coating on the biological properties of a magnesium based alloy

Magnesium alloys have been widely investigated as biodegradable cardiovascular temporal implants due to their better mechanical properties and biocompatibility, but the rapid degradation limited its application. In this study, the anodic oxidation-Cu structure was used to improve the adhesive strength and stability between poly-β-hydroxybutyrate (PHB) and magnesium alloys, and the effects of anodic oxidation magnesium alloys with copper film and PHB film (MACP) on human umbilical vein endothelial cells (HUVECs), blood compatibility and antibacterial properties were investigated in this research. As the result, the MACP structure had a stable structure and better corrosion resistance, and significant antibacterial properties. The coating would not affect the original excellent biocompatibility of the magnesium alloy. It was indicated that MACP was a potential surface modification strategy for vascular stents candidate material.

In vitro corrosion resistance of a Ta2O5 nanofilm on MAO coated magnesium alloy AZ31 by atomic layer deposition

Micro-arc oxidation (MAO) coating with outstanding adhesion strength to Mg alloys has attracted more and more attention. However, owing to the porous structure, aggressive ions easily invaded the MAO/substrate interface through the through pores, limiting long-term corrosion resistance. Therefore, a dense and biocompatible tantalum oxide (Ta2O5) nanofilm was deposited on MAO coated Mg alloy AZ31 through atomic layer deposition (ALD) technique to seal the micropores and regulate the degradation rate. Surface micrography, chemical compositions and crystallographic structure were characterized using FE-SEM, EDS, XPS and XRD. The corrosion resistance of all samples was evaluated through electrochemical and hydrogen evolution tests. Results revealed that the Ta2O5 film mainly existed in the form of amorphousness. Moreover, uniform deposition of Ta2O5 film and effective sealing of micropores and microcracks in MAO coating were achieved. The current density (i corr) of the composite coating decreased three orders of magnitude than that of the substrate and MAO coating, improving corrosion resistance. Besides, the formation and corrosion resistance mechanisms of the composite coating were proposed.

The Potential Selective Cytotoxicity of Poly (L- Lactic Acid)-Based Scaffolds Functionalized with Nanohydroxyapatite and Europium (III) Ions toward Osteosarcoma Cells

Osteosarcoma (OSA) is malignant bone tumor, occurring in children and adults, characterized by poor prognosis. Despite advances in chemotherapy and surgical techniques, the survival of osteosarcoma patients is not improving significantly. Currently, great efforts are taken to identify novel selective strategies, distinguishing between cancer and normal cells. This includes development of biomimetic scaffolds with anticancer properties that can simultaneously support and modulate proper regeneration of bone tissue. In this study cytotoxicity of scaffolds composed from poly (L-lactic acid) functionalized with nanohydroxyapatite (nHAp) and doped with europium (III) ions-10 wt % 3 mol % Eu³⁺: nHAp@PLLA was tested using human osteosarcoma cells: U-2 OS, Saos-2 and MG-63. Human adipose tissue-derived stromal cells (HuASCs) were used as non-transformed cells to determine the selective cytotoxicity of the carrier. Analysis included evaluation of cells morphology (confocal/scanning electron microscopy (SEM)), metabolic activity and apoptosis profile in cultures on the scaffolds. Results obtained indicated on high cytotoxicity of scaffolds toward all OSA cell lines, associated with a decrease of cells' viability, deterioration of metabolic activity and activation of apoptotic factors determined at mRNA and miRNA levels. Simultaneously, the biomaterials did not affect HuASCs' viability and proliferation rate. Obtained scaffolds showed a bioimaging function, due to functionalization with luminescent europium ions, and thus may find application in theranostics treatment of OSA.