Preparation, characterization, corrosion behavior and cytocompatibility of NiTiO3 nanosheets hydrothermally synthesized on biomedical NiTi alloy

Synergistic Biocidal Effects of Curcumin, Chitosan, and Nickel Titanate-Based Nanohybrids for Enhanced Antibacterial and Anticancer Therapies

Microbial infections and colorectal cancer are significant contributors to mortality and morbidity, necessitating prompt action. In the present work, NiTiO3 (NT), curcumin-loaded NiTiO3 (CUNT), chitosan-loaded NiTiO3 (CHNT), and both curcumin and chitosan-loaded NiTiO3 (CUCHNT) hybrid nanomaterials (HNMs) were systematically prepared using Psidium guajava leaf extract. PXRD studies revealed that NT, CUNT, CHNT, and CUCHNT exhibited a rhombohedral structure with the R3̅ space group with mean crystallite sizes of ∼66.41, ∼61.94, ∼61.65, and ∼65.12 nm, respectively. Band gap energies were estimated as ∼3.10, ∼3.15, ∼3.14, and ∼3.15 eV for NT, CUNT, CHNT, and CUCHNT, respectively. Antibacterial efficacies of synthesized HNMs were analyzed against both Gram-positive (G+) and Gram-negative (G-) bacteria using the well diffusion method, and the zone of inhibition (ZOI) exhibited by NT, CUNT, CHNT, and CUCHNT against Staphylococcus aureus were 11.5, 13, 12, and 17.5 mm, respectively; those of Staphylococcus pneumoniae were 9, 13.5, 11, and 14 mm, respectively; those of Klebsiella pneumoniae were 10, 9.5, 10, and 17 mm, respectively; and those of Escherichia coli were 11, 11.5, 13, and 16.5 mm, respectively. ZOI results showed that CUCHNT HNMs have superior antibacterial efficacies for all tested bacterial strains compared to NT, CUNT, and CHNT. Cytotoxic capabilities of the synthesized HNMs were analyzed using the MTT assay against the HCT-116 colorectal carcinoma cell line. All HNMs showed significant anticancer activity, with CUCHNT exhibiting the most pronounced activity, having an IC50 value of 87 μg/mL. Morphological changes and cell death mechanisms of synthesized HNMs were studied using dual AO/EtBr, H2DCFDA, and JC-1 staining. These findings emphasize that biosynthesized CUCHNT HNMs using P. guajava leaf extract could be a potential therapeutic agent for antimicrobial and anticancer applications.

Multifunctional coatings of nickel-titanium implant toward promote osseointegration after operation of bone tumor and clinical application: a review

Metal implants, especially Ni-Ti shape memory alloy (Ni-Ti SMA) implants, have increasingly become the first choice for fracture and massive bone defects after orthopedic bone tumor surgery. In this paper, the internal composition and shape memory properties of Ni-Ti shape memory alloy were studied. In addition, the effects of porous Ni-Ti SMA on osseointegration, and the effects of surface hydrophobicity and hydrophilicity on the osseointegration of Ni-Ti implants were also investigated. In addition, the effect of surface coating modification technology of Ni-Ti shape memory alloy on bone bonding was also studied. Several kinds of Ni-Ti alloy implants commonly used in orthopedic clinic and their advantages and disadvantages were introduced. The surface changes of Ni-Ti alloy implants promote bone fusion, enhance the adhesion of red blood cells and platelets, promote local tissue regeneration and fracture healing. In the field of orthopaedics, the use of Ni-Ti shape memory alloy implants significantly promoted clinical development. Due to the introduction of the coating, the osseointegration and biocompatibility of the implant surface have been enhanced, and the success rate of the implant has been greatly improved.

Fabrication of Antibacterial TiO2 Nanostructured Surfaces Using the Hydrothermal Method

Implant-associated infections (IAI) are a common cause for implant failure, increased medical costs, and critical for patient healthcare. Infections are a result of bacterial colonization, which leads to biofilm formation on the implant surface. Nanostructured surfaces have been shown to have the potential to inhibit bacterial adhesion mainly due to antibacterial efficacy of their unique surface nanotopography. The change in topography affects the physicochemical properties of their surface such as surface chemistry, morphology, wettability, surface charge, and even electric field which influences the biological response. In this study, a conventional and cost-effective hydrothermal method was used to fabricate nanoscale protrusions of various dimensions on the surface of Ti, Ti₆Al₄V, and NiTi materials, commonly used in biomedical applications. The morphology, surface chemistry, and wettability were analyzed using scanning electron microscopy (SEM), X-ray photoemission spectroscopy (XPS), and water contact angle analysis. The antibacterial efficacy of the synthesized nanostructures was analyzed by the use of Escherichia coli bacterial strain. XPS analysis revealed that the concentration of oxygen and titanium increased on Ti and Ti₆Al₄V, which indicates that TiO₂ is formed on the surface. The concentration of oxygen and titanium however decreased on the NiTi surface after hydrothermal treatment, and also a small amount of Ni was detected. SEM analysis showed that by hydrothermal treatment alterations in the surface topography of the TiO₂ layer could be achieved. The oxide layer on the NiTi prepared by the hydrothermal method contains a low amount of Ni (2.8 atom %), which is especially important for implantable materials. The results revealed that nanostructured surfaces significantly reduced bacterial adhesion on the Ti, Ti₆Al₄V, and NiTi surface compared to the untreated surfaces used as a control. Furthermore, two sterilization techniques were also studied to evaluate the stability of the nanostructure and its influence on the antibacterial activity. Sterilization with UV light seems to more efficiently inhibit bacterial growth on the hydrothermally modified Ti₆Al₄V surface, which was further reduced for hydrothermally treated Ti and NiTi. The developed nanostructured surfaces of Ti and its alloys can pave a way for the fabrication of antibacterial surfaces that reduce the likelihood of IAI.

Nickel-Catcher-Doped Zwitterionic Hydrogel Coating on Nickel-Titanium Alloy Toward Capture and Detection of Nickel Ions

Nickel-titanium (NiTi) alloys show broad applicability in biomedical fields. However, the unexpected aggregation of bacteria and the corrosion of body fluid on NiTi-based medical devices often lead to the leakage of nickel ions, resulting in inevitable allergic and cytotoxic activities. Therefore, the capture and detection of nickel ions are important to avoid serious adverse reactions caused by NiTi-based medical devices. Herein, we presented a nickel ion capture strategy by the combination of zwitterionic hydrogels as anti-bacteria layers and carbon disulfide (CS₂) components as nickel-catchers (Ni-catchers). On the one hand, the hydration layer of zwitterionic hydrogel can efficiently inhibit bacteria adhesion and reduce nickel ions leakage from NiTi corrosion. On the other hand, Ni-catchers can capture leaked nickel ions from NiTi alloy actively by chelation reaction. Therefore, this strategy shows great capabilities in resisting bacteria adhesion and capturing nickel ions, providing the potential possibility for the detection of nickel ion leakage for implantable biomedical materials and devices.

Regulation of endothelial functionality through direct and immunomodulatory effects by Ni-Ti-O nanospindles on NiTi alloy

Stent implantation has become one of the most widely used methods for the treatment of cardiovascular diseases. However, endothelial dysfunction and abnormal inflammatory response following implantation may lead to delayed re-endothelialization, resulting in vascular restenosis and stent thrombus. To address the concerns, we constructed nanospindles composed of TiO₂ and Ti₄Ni₂O through hydrothermal treatment of amorphous Ni-Ti-O nanopores anodically grown on NiTi alloy. The results show the treatment can significantly improve hydrophilicity and reduce Ni ion release, essentially independent of hydrothermal duration. The nanospindle surfaces not only promote the expression of endothelial functionality but also activate macrophages to induce a favorable immune response, downregulate pro-inflammatory M1 markers and upregulate pro-healing M2 markers. Moreover, nitric oxide (NO) synthesis, VEGF secretion, and migration of endothelial cells are enhanced after cultured in macrophage conditioned medium. The nanospindles thus are promising as vascular stent coatings to promote re-endothelization.