Since the last few decades, the development of smart hydrogels, which can respond to stimuli and adapt their responses based on external cues from their environments, has become a thriving research frontier in the biomedical engineering field. Nowadays, drug delivery systems have received great attention and smart hydrogels can be potentially used in these systems due to their high stability, physicochemical properties, and biocompatibility. Smart hydrogels can change their hydrophilicity, swelling ability, physical properties, and molecules permeability, influenced by external stimuli such as pH, temperature, electrical and magnetic fields, light, and the biomolecules’ concentration, thus resulting in the controlled release of the loaded drugs. Herein, this review encompasses the latest investigations in the field of stimuli-responsive drug-loaded hydrogels and our contribution to this matter.
Orthopedic implants, such as those made of stainless steel, cobalt (Co)-based alloys and titanium (Ti) alloys, are commonly used to stabilize, protect, improve, replace or regenerate damaged musculoskeletal tissues both anatomically and functionally in millions of bone injury patients. The biggest drawback of these metallic biomaterials is their non-degradability in the body environment. Magnesium (Mg) and magnesium-based alloys are a new generation of degradable implant materials that have attracted great attention in the past 10 years. There are several advantages of magnesium-based alloys for orthopedic application over other metallic biomaterials. First, magnesium is an essential element for many biological activities, including enzymatic reactions, the formation of apatite and bone cell adsorption. Second, their mechanical properties, including density, elastic modulus and compressive yield strength, are much closer to those of natural bone, and, therefore, they can avoid the stress-shielding effect. Third, magnesium alloys can eliminate the necessity of a second surgery to remove permanent bone implants. Recent results show that alloying of magnesium with aluminum (Al), zinc (Zn), calcium (Ca), zirconium (Zr), yttrium (Y) and rare-earth elements can significantly improve its corrosion resistance and mechanical strength. This paper reviews and compares the mechanical properties, corrosion resistance and biocompatibility of currently researched magnesium-based alloys for use in medical implant applications.
Topography and surface chemistry can significantly affect biofilm formation on dental implants. Recently, the γ-TiAl alloy was considered as the most reliable candidates for the preparation of dental implants because of its excellent mechanical strength, chemical stability and biocompatibility. The emphasis of this study lies in the effects of high-speed milling assisted the minimum quantity of lubrication (HSM-MQL), micro-current wire electrical discharge machining (mWEDM), Er,Cr:YSGG laser and sandblasting/largegrit/acid-etching (SLA) treatments on surface morphology, topography, chemical composition, wettability and biofilm-associated infections on the surface of each group. The surface-treated samples were analyzed using a scanning electron microscope (SEM), SEM surface reconstruction, energy dispersive x-ray spectroscopy (EDS) and water contact angle measuring system. SEM and topography images of mWEDM and laser-treated surfaces showed more irregular surfaces compared to SLA and HSM-MQL surfaces. Results showed that mWEDM and laser-treated surfaces revealed hydrophobic behavior. A significant decrease of biofilm formation was observed on mWEDM treated surface due to the hydrophobicity and existence of the copper element in the recast layer chemical composition. Moreover, EDS confirmed that the zirconium, silicon, and fluorine elements were decorated onto the SLA treated γ-TiAl surface that can have a direct effect on the anti-bacterial activity.
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