Background Critical-sized bone defects remain a major challenge in orthopedic practice. Biomimetic scaffolds are designed to support bone regeneration by reproducing the structural and functional characteristics of native bone. Objective To synthesize advances in multidimensional biomimetic bone scaffolds, examine their roles in bone regeneration, and identify key barriers to clinical translation. Methods This narrative review drew primarily on literature identified through PubMed and Google Scholar, with an emphasis on publications from the past five years. Representative original studies and reviews were selected based on their relevance to biomimetic scaffold design, regenerative mechanisms, pathological bone defects, and fabrication technologies. Earlier publications were included where needed to provide foundational context. The selected literature was synthesized thematically across complementary aspects of scaffold design and application. Results The synthesis integrates five interconnected design dimensions: composition, hierarchical structure, mechanical properties, biophysical signaling, and biological regulation. These dimensions link scaffold design to controlled drug delivery, reconstruction of a vascularized microenvironment, and neuro-osseous coupling. Preclinical studies report promising regenerative outcomes in models of infected, post-tumor-resection, and diabetic bone defects. Three-dimensional printing, electrospinning, and self-assembly offer complementary fabrication approaches for implementing these strategies across diverse material classes. However, limited clinical evidence and unresolved challenges in long-term biosafety, mechanical compatibility, functional stability, and reproducible, patient-specific manufacturing continue to hinder translation. Conclusion Multidimensional biomimetic design provides a framework for coordinating structural support with biological regulation during bone repair. Further progress requires validation of long-term safety and functional performance, alongside manufacturing approaches that balance functional complexity with clinical feasibility.
Background Magnesium-based alloys have emerged as promising biodegradable materials for temporary biomedical implants due to their biocompatibility, low density, and elastic modulus similar to natural bone. However, their rapid degradation in physiological environments limits their clinical application, making surface modification strategies necessary to improve corrosion resistance and mechanical performance. Objective The aim of this study was to evaluate the effect of ionic nitriding on the microstructure, corrosion resistance, mechanical properties, and cytocompatibility of Mg–Zn–Ca–Mn biodegradable alloys. Methods Mg–Zn–Ca–Mn quaternary alloys were synthesized by powder metallurgy and subsequently surface modified by ionic nitriding. The microstructure and phase composition were characterized using scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), and X-ray diffraction (XRD). Corrosion behavior was evaluated through electrochemical tests in Hank's solution, while mechanical properties were assessed using Vickers microhardness measurements. Cytocompatibility was analyzed by indirect cytotoxicity tests using fibroblast and keratinocyte cells. Results The nitrided alloys exhibited improved corrosion resistance, evidenced by lower corrosion current densities and more noble corrosion potentials compared with pure magnesium. In addition, ionic nitriding increased the Vickers microhardness by approximately 42–48%. Cytotoxicity assays showed that the Mg64–Zn30–Ca5–Mn1 alloy and its nitrided counterpart-maintained cell viability above 70%, indicating acceptable cytocompatibility. Conclusion Ionic nitriding is an effective surface modification technique to enhance the corrosion resistance, mechanical properties, and biological performance of Mg–Zn–Ca–Mn biodegradable alloys, demonstrating their potential for use as temporary biomedical implant materials.
Background316L stainless steel (SS) is widely used in biomedical implant applications because of its excellent mechanical properties, corrosion resistance, biocompatibility, and cost-effectiveness. However, its long-term performance in physiological environments is limited by localized corrosion, ion release, and inadequate surface interactions with biological tissues. Surface modification using Ti-based physical vapor deposition (PVD) coatings has emerged as a promising strategy to enhance the corrosion resistance and durability of implant materials.ObjectiveThis study aimed to investigate the effect of Ti-based PVD coatings, namely TiCoCr, TiN, and TiO2, on the corrosion behavior of 316L SS under simulated physiological conditions.MethodsTiCoCr, TiN, and TiO2 coatings were deposited onto 316L SS substrates using the PVD technique. The corrosion performance of the coated and uncoated samples was evaluated in phosphate-buffered saline (PBS), Hanks' solution, and Ringer's solution at 37 °C. Electrochemical corrosion parameters, including corrosion potential and corrosion current density, were analyzed to assess the effectiveness of the coatings.ResultsAll Ti-based coatings improved the corrosion resistance of 316L SS compared with the uncoated substrate. Among the investigated coatings, the TiCoCr coating deposited for 90 min exhibited the best corrosion performance. In Ringer's solution, the coating showed a corrosion potential of -0.0504 V and a corrosion current density of 4.74 × 10-6 A/cm2. In Hanks' solution, the same coating demonstrated a corrosion potential of -0.1815 V and a corrosion current density of 5.0537 × 10-6 A/cm2. The enhanced corrosion resistance was attributed to the protective and stable nature of the Ti-based coating layer.ConclusionThe TiCoCr, TiN, and TiO2 PVD coatings significantly enhanced the corrosion resistance of 316L SS in simulated physiological environments. Among them, the TiCoCr coating demonstrated superior corrosion protection, indicating its strong potential for improving the long-term reliability and performance of biomedical implants.
BackgroundAllergic conjunctivitis is an inflammatory disorder of the conjunctiva triggered by allergens. Although topical eye drops are widely used, their efficacy is limited by rapid precorneal clearance and low ocular bioavailability. Hyaluronic acid (HA)-based nanoparticles may prolong ocular residence time and improve drug delivery.ObjectiveThis study aimed to develop and evaluate chitosan- and polyethylenimine (PEI)-cross-linked HA nanoparticles to improve drug encapsulation efficiency and achieve sustained release of diclofenac sodium for allergic conjunctivitis.MethodsHA nanoparticles were prepared by EDC/sulfo-NHS-mediated cross-linking with chitosan or PEI. Nanoparticle properties were characterized by FTIR, 1H-NMR, DLS, and HRTEM. Encapsulation efficiency, in vitro drug release, and cytocompatibility in SIRC cells were evaluated.ResultsFTIR and 1H-NMR analyses confirmed successful nanoparticle formation, cross-linking, and drug incorporation. H1P1-01DS exhibited a particle size of approximately 170 nm and a significantly higher encapsulation efficiency (82.0%) than the HA-chitosan formulations. Drug release followed a biphasic profile, with H1P1-01DS achieving approximately 90% cumulative release within 180 min, compared with 68-83% for HA-chitosan formulations. WST-1 assays demonstrated favorable cytocompatibility across all formulations, although cell viability decreased in a dose-dependent manner at higher concentrations.ConclusionThe HA-PEI nanoparticle formulation (H1P1-01DS) demonstrated sustained drug release, high encapsulation efficiency, and favorable biocompatibility, indicating its potential as a long-acting ocular drug delivery system for allergic conjunctivitis.
Background Hydroxyapatite (HA) coatings on titanium (Ti) implants are widely studied owing to their biocompatibility and osteoconductivity. However, the effect of substrate temperature during flame spraying on coating performance remains unclear. Objective This study investigated the influence of substrate temperature on the microstructure, mechanical properties, and electrochemical behavior of flame-sprayed HA coatings on Ti implants. Methods HA coatings were deposited on commercially pure Ti Grade 2 substrates by flame spraying at room temperature (RT) and 300 °C. The coatings were characterized by XRD, FTIR, XPS, SEM, and EDS. Surface roughness, adhesion strength, abrasion resistance, potentiodynamic polarization, and electrochemical impedance spectroscopy were evaluated. Results Substrate heating at 300 °C modified the crystalline phase composition and slightly increased the apparent HA crystallite size and crystalline peak index. The 300 °C coating exhibited a more compact surface morphology, higher adhesion strength, lower abrasion-induced mass loss, lower corrosion current density, and higher charge transfer resistance than the RT coating. Conclusion Substrate heating at 300 °C improved the mechanical durability and corrosion resistance of flame-sprayed HA coatings, indicating its usefulness for enhancing Ti implant coating performance.
