Encapsulation and Release of Doxorubicin from TiO2 Nanotubes: Experiment, Density Functional Theory Calculations, and Molecular Dynamics Simulation

Design of engineered nanoparticles for biomedical applications by computational modeling

Engineered nanoparticles exhibit superior physicochemical, antibacterial, optical, and sensing properties compared to their bulk counterparts, rendering them attractive for biomedical applications. However, given that nanoparticle properties are sensitive to their nanostructural characteristics and their chemical stability is largely affected by physiological conditions, nanoparticle behavior can be unpredictable in vivo, requiring careful surface modification to ensure biocompatibility, prevent rapid aggregation, and maintain functionality under biological environments. Therefore, understanding the mechanisms of nanoparticle formation and macroscopic behavior in physiological media is essential for the development of structure-property relationships and, their rational design for biomedical applications. Computational simulations provide insight into nanoscale phenomena and nanoparticle dynamics, expediting material discovery and innovation. This review provides an overview of the process design and characterization of metallic and metal oxide nanoparticles with an emphasis on atomistic and mesoscale simulations for their application in bionanomedicine.

Nanoscale CaO2-Loaded Surface-Engineered Iodine-125 Seed with Sustained Self-Oxygenation for Sensitized Tumor Brachytherapy

Iodine-125 (125I) brachytherapy (BT) is renowned for its precision and effectiveness in delivering localized radiation doses to solid tumors. However, the therapeutic efficacy of traditional125I seed is often limited due to the inherent and acquired radioresistance. Based on the importance of tumor hypoxia in radioresistance, a novel "in situ oxygen-supplement" surface-modified radioactive 125I seed (125I@TNT-CaO2) is designed and constructed to overcome hypoxia-induced radioresistance in tumor BT. Titanium dioxide nanotubes (TNTs) are modified on the titanium shell of traditional 125I seed and loaded with nanoscale calcium peroxide (CaO2), further leading to a sustained release of O2. This in situ oxygen delivery system sensitizes hypoxic tumor regions to 125I BT, significantly improving therapeutic efficacy by inducing more ROS generation and DNA damage. Both in vitro and in vivo experiments demonstrate enhanced tumor suppression and apoptosis, with elevated O2 levels further inhibiting hypoxia-inducible factor 1-alpha (HIF-1α) and its associated signaling pathways. This innovative 125I@TNT-CaO2 seed presents a promising paradigm to enhance the effectiveness of BT by reversing hypoxia-mediated resistance.

Synthesis of Urchin-Like Au@TiO2 Nano-Carriers as a Drug-Loading System Toward Cancer Treatment

In recent years, improving the pharmaceutical properties of drug delivery for anti-cancer treatment has become increasingly important. This is necessary to address challenges related to absorption, distribution, and stability. One potential approach solution is to attach the drug to a carrier system, such as functional noble nanomaterials, in order to improve the control of drug release and stability. Core-satellite nanoparticles (CSN) with an anisotropic morphology have enormous potential for targeted drug delivery and cancer treatment because of their large surface area, exceptional stability, and biocompatibility. We used a simple seed-mediated approach to synthesize urchin-like gold nanoparticles (ULGNPs) with a high aspect ratio and a dense network of 49 nm-sized branches, using seed solution, silver nitrate, and ascorbic acid. The ULGNPs were synthesized without a surfactant and then encapsulated with thin layers of amorphous TiO2 (ULGNPs@TiO2), resulting in an average overall size of 136±15 nm with a 27.5 nm TiO2 layer. Doxorubicin (Dox) was chosen as a model drug to assess the distribution carrier ability of ULGNPs@TiO2 core-satellite nanoparticles. The results showed 86.5 % Dox loading and 72.3 % release capacity at pH 5. The anti-cancer ability of ULGNPs@TiO2-Dox was meticulously assessed using breast cancer MCF-7 cells in the WST-1 assay. The results revealed that ULGNPs@TiO2-Dox exhibited approximately 92 % toxicity in MCF-7 cells compared to the free Dox of 89.6 % at low concentrations (5 ppm). Based on the simulation results for loading ULGNPs@TiO2 with Dox, it was observed that a structure containing five layers of Au (111) with three fixed bottom layers and two relaxed top layers, in addition to six TiO2 (100) layers, was analyzed using Grimme's DFT-D3 dispersion corrections (Scheme 1). The density functional theory (DFT) adsorption energy (Eads) shows that the amorphous TiO2 increases the Dox loading activity of ULGNPs, with Eads=-3.85 eV, negatively higher than isolated ULGNPs (Eads=-2.87 eV) and TiO2 alone (Eads=-3.61 eV). This drug carrier design has the potential to revolutionize anti-cancer treatment.

Reduced TiO2 Nanotubes/Silk Fibroin/ZnO as a Promising Hybrid Antibacterial Coating

The current research aims to elucidate the influence of reduction process of TiO2 nanostructures on the surface properties of a bioinspired Ti modified implant, considering that the interface between a biomaterial surface and the living tissue plays an important role for this interaction. The production of reduced TiO2 nanotubes (RNT) with lower band gap is optimized and their performance is compared with those of simple TiO2 nanotubes (NT). The more conductive surfaces provided by the presence of RNT on Ti, allow a facile deposition of silk fibroin (SF) film using the electrochemical deposition method. This hybrid film is then functionalized with ZnO nanoparticles, to improve the antibacterial effect of the coating. The modified Ti surface is evaluated in terms of surface chemistry, morphology and roughness, wettability, surface energy, surface charge and antibacterial properties. Surface analysis such as SEM, AFM, FTIR and contact angle measurements were performed to obtain topographical features and wettability. FT-IR analysis confirms that SF was effectively attached to TiO2 nanotubes surfaces. The electrochemical deposition of SF and SF-ZnO reduced the interior diameter of nanotubes from ~85 nm to approx. 50-60 nm. All modified surfaces have a hydrophilic character.

Controlled growth of titanium dioxide nanotubes for doxorubicin loading and studies of in vitro antitumor activity

Titanium dioxide (TiO₂) materials are suitable for use as drug carriers due to their natural biocompatibility and nontoxicity. The aim of the study presented in this paper was to investigate the controlled growth of TiO₂ nanotubes (TiO₂ NTs) of different sizes via an anodization method, in order to delineate whether the size of NTs governs their drug loading and release profile as well as their antitumor efficiency. TiO₂ NTs were tailored to sizes ranging from 25 nm to 200 nm according to the anodization voltage employed. The TiO₂ NTs obtained by this process were characterized using scanning electron microscopy, transmission electron microscopy, and dynamic light scattering The larger TiO₂ NTs exhibited greatly improved doxorubicin (DOX)-loading capacity (up to 37.5 wt%), which contributed to their outstanding cell-killing ability, as evidenced by their lower half-maximal inhibitory concentration (IC50). Comparisons were carried out of cellular uptake and intracellular release rates of DOX for large and small TiO₂ NTs loaded with DOX. The results showed that the larger TiO₂ NTs represent a promising therapeutic carrier for drug loading and controlled release, which could improve cancer treatment outcomes. Therefore, TiO₂ NTs of larger size are useful substances with drug-loading potency that may be used in a wide range of medical applications.

Experimental Studies on TiO2 NT with Metal Dopants through Co-Precipitation, Sol-Gel, Hydrothermal Scheme and Corresponding Computational Molecular Evaluations

In the last decade, TiO₂ nanotubes have attracted the attention of the scientific community and industry due to their exceptional photocatalytic properties, opening a wide range of additional applications in the fields of renewable energy, sensors, supercapacitors, and the pharmaceutical industry. However, their use is limited because their band gap is tied to the visible light spectrum. Therefore, it is essential to dope them with metals to extend their physicochemical advantages. In this review, we provide a brief overview of the preparation of metal-doped TiO₂ nanotubes. We address hydrothermal and alteration methods that have been used to study the effects of different metal dopants on the structural, morphological, and optoelectrical properties of anatase and rutile nanotubes. The progress of DFT studies on the metal doping of TiO₂ nanoparticles is discussed. In addition, the traditional models and their confirmation of the results of the experiment with TiO₂ nanotubes are reviewed, as well as the use of TNT in various applications and the future prospects for its development in other fields. We focus on the comprehensive analysis and practical significance of the development of TiO₂ hybrid materials and the need for a better understanding of the structural-chemical properties of anatase TiO₂ nanotubes with metal doping for ion storage devices such as batteries.

Anodic TiO2 Nanotubes: Tailoring Osteoinduction via Drug Delivery

TiO₂ nanostructures and more specifically nanotubes have gained significant attention in biomedical applications, due to their controlled nanoscale topography in the sub-100 nm range, high surface area, chemical resistance, and biocompatibility. Here we review the crucial aspects related to morphology and properties of TiO₂ nanotubes obtained by electrochemical anodization of titanium for the biomedical field. Following the discussion of TiO₂ nanotopographical characterization, the advantages of anodic TiO₂ nanotubes will be introduced, such as their high surface area controlled by the morphological parameters (diameter and length), which provides better adsorption/linkage of bioactive molecules. We further discuss the key interactions with bone-related cells including osteoblast and stem cells in in vitro cell culture conditions, thus evaluating the cell response on various nanotubular structures. In addition, the synergistic effects of electrical stimulation on cells for enhancing bone formation combining with the nanoscale environmental cues from nanotopography will be further discussed. The present review also overviews the current state of drug delivery applications using TiO₂ nanotubes for increased osseointegration and discusses the advantages, drawbacks, and prospects of drug delivery applications via these anodic TiO₂ nanotubes.