TiO2 -coated fluoride nanoparticles for dental multimodal optical imaging

Visualization of Small Vessels by Micro-Computed Tomography Using Titanium Dioxide Nanoparticles as a Novel Contrast Agent

Angiography by means of micro-computed tomography (m-CT) is extensively used for the diagnosis of vasculature disorders. To establish a connection between m-CT images and genuine histopathology findings, we developed two novel titanium dioxide nanoparticle (TiO2-NP)-based perfusion contrast agents: TiNpCA-1 and TiNpCA-2. Three-dimensionally reconstructed m-CT images in mice perfused with these contrast agents showed high resolution and accuracy in various organs without deformation or dilation of vessels. Vessels < 20  μm in diameter were clearly visualized by m-CT, and capillaries of 4 μm in diameter were visualized by nano-CT. After perfusion, the contrast agents were kept in the vessels by the formation of an aggregate with ethanol. Histological samples were prepared from CT-scanned specimens. No perfusion-induced damage or abnormal structures were observed. The signals of the contrast agents were detected clearly, and the tissue histology was of adequate quality for pathological diagnosis. Agglomerates of TiO2-NPs were present in both agents; their approximate sizes were 1.0 and 6.0 μm in TiNpCA-1 and 1.5 μm in TiNpCA-2. We considered that these agglomerates were trapped within capillaries at the beginning of perfusion. And at the end of perfusion, vessels of larger size were filled with agglomerates. These findings suggest a direct correlation between the signal intensity in m-CT imaging and the volume of contrast agent entering the vessels, indicating a quantitative aspect to the system. The low K-edge value of titanium (4.6 KeV) ensures that the signal intensity of the contrast agent remains unaffected at low energies (40 KeV). Lower energy levels improve the contrast-to-noise ratio. Consequently, using titanium dioxide as a contrast agent allows us to achieve a higher contrast-to-noise ratio while maintaining a favorable signal-to-noise ratio. Our results strongly support the notion that TiO2-NPs as a contrast agents hold promise not only for investigating circulatory disorders in experimental pathology but also for uncovering new insights in anatomical physiology.

Recent advances in nanomaterial-based biosensor for periodontitis detection

Periodontitis, a chronic inflammatory condition caused by bacteria, often causes gradual destruction of the components that support teeth, such as the alveolar bone, cementum, periodontal ligament, and gingiva. This ultimately results in teeth becoming loose and eventually falling out. Timely identification has a crucial role in preventing and controlling its progression. Clinical measures are used to diagnose periodontitis. However, now, there is a hunt for alternative diagnostic and monitoring methods due to the progress of technology. Various biomarkers have been assessed using multiple bodily fluids as sample sources. Furthermore, conventional periodontal categorization factors do not provide significant insights into the present disease activity, severity and amount of tissue damage, future development, and responsiveness to treatment. In recent times, there has been a growing utilization of nanoparticle (NP)-based detection strategies to create quick and efficient detection assays. Every single one of these platforms leverages the distinct characteristics of NPs to identify periodontitis. Plasmonic NPs include metal NPs, quantum dots (QDs), carbon base NPs, and nanozymes, exceptionally potent light absorbers and scatterers. These find application in labeling, surface-enhanced spectroscopy, and color-changing sensors. Fluorescent NPs function as photostable and sensitive instruments capable of labeling various biological targets. This article presents a comprehensive summary of the latest developments in the effective utilization of various NPs to detect periodontitis.

Monitoring silver diamine fluoride application with optical coherence tomography and thermal imaging: An in vitro proof of concept study

OBJECTIVES

The purpose of this study was to show that optical coherence tomography (OCT) and thermal imaging can be used to monitor changes in the structure and activity of caries lesions over time after treatment with silver diamine fluoride (SDF).

METHODS

Artificial caries lesions were formed on enamel and dentin bovine blocks. Each block was partitioned into five windows with the central three windows exposed to a demineralization solution to create lesions: one sound window served as a sound control (SC), one sound window was exposed to SDF to serve as a test control (SCT), one lesion window served as a lesion control (LC), one lesion window received one application of SDF (L1), while the other lesion window received two applications of SDF (L2). Each window was scanned using OCT before SDF application, and every week subsequently, for 12 weeks after initial SDF treatment. Changes in the mean intensity and the width of the peak of increased reflectivity due to the lesion and SDF along with the intensity at a depth of 180 µm from the surface representing optical penetration through the lesion were monitored. Changes in the heat lost, ΔQ (temperature integrated over time) of each window during drying with air were also monitored using a thermal imaging camera. Transverse microradiography (TMR), and high-resolution microscopy were also used for the analysis of selected samples.

RESULTS

The reflectivity and optical penetration of sound and lesion areas of enamel and dentin manifested significant changes in OCT images after SDF application. Thermal imaging showed significant differences in ΔQ indicative of permeability changes in the sound and lesion areas of enamel and dentin after SDF application.

Band gap engineering of Ce-doped anatase TiO2 through solid solubility mechanisms and new defect equilibria formalism

The present work reports a detailed mechanistic interpretation of the role of the solubility of dopants and resultant midgap defect energies in band gap engineering. While there is a general perception that a single dopant is associated with single solubility and defect mechanisms, in reality, the potential for multiple solubility and defect mechanisms requires a more nuanced interpretation. Similarly, Kröger-Vink defect equilibria assume that stoichiometries during substitutional and interstitial solid solubility as well as Schottky and Frenkel pair formation are compensated by the diffusion of matrix ions to the grain boundaries or surface. However, this approach does not allow the possibility that stoichiometry is uncompensated, where diffusion of the matrix ion to lattice interstices occurs, followed by charge compensation by redox of this ion. Consequently, a modified defect equilibria formalism has been developed in order to allow description of this situation. Experimental data for the structural, chemical, semiconducting, and photocatalytic properties as a function of doping level are correlated with conceptual structural models, a comprehensive energy band diagram, and the corresponding defect equilibria. These correlations reveal the complex mechanisms of the interrelated solubility and defect formation mechanisms, which change significantly and irregularly as a function of small changes in doping level. The analyses confirm that the assumption of single mechanisms of solid solubility and defect formation may be simplifications of more complex processes. The generation of (1) a matrix of complementary characterisation and analytical data, (2) the calculation of a complete energy band diagram, (3) consideration of charge compensation mechanisms and redox beyond the limitations of Kröger-Vink approaches, and (4) the development of models of corresponding structural analogies combine to create a new approach to interpret and explain experimental data. These strategies allow deconstruction of these complex issues and thus targeting of optimal and possibly unique doping levels to achieve lattice configurations that may be energetically and structurally unfavorable. These approaches then can be applied to other doped semiconducting systems.