Dual-Action Gemcitabine Delivery: Chitosan-Magnetite-Zeolite Capsules for Targeted Cancer Therapy and Antibacterial Defense.

Cancer and infectious diseases are two of the world's major public health problems. Gemcitabine (GEM) is an effective chemotherapeutic agent against several types of cancer. In this study, we developed macrocapsules incorporating GEM into a chitosan matrix blended with magnetite and zeolite by ionic gelation.

An approach to investigate the crystallographic unit cell of human tooth enamel.

Human tooth enamel (HTE) is the hardest tissue in the human body and its structural organization shows a hierarchical composite material. At the nanometric level, HTE is composed of approximately 97% hydroxyapatite [HAP, Ca(PO)(OH)] as inorganic phase, and of 3% as organic phase and water. However, it is still controversial whether the hexagonal HAP phase crystallizes in P6/m or another space group.

Electron microscopy analysis of the thermal phase transition from hydroxyapatita to β-TCP observed in human teeth.

Samples of enamel and dentin from human molar teeth were heated in air from room temperature (25°C) up to 1200°C and the phase transition from hydroxyapatite (HAP) to tricalcium phosphate (β-TCP) was recorded. The changes produced in morphology and chemical composition in the tooth during heating were analysed by light microscopy, scanning electron microscopy (SEM), characteristic x-ray energy dispersion spectroscopy (EDS), x-ray diffraction (XRD), electron diffraction, transmission electron microscopy (TEM) and high-resolution electron microscopy (HRTEM). The results indicated a high correlation relationship among Ca content, P content, O content and Na content, and the existence of the Kirkendall effect during the HAP- β-TCP phase transition.

Evaluation of crystalline indexes obtained through infrared spectroscopy and x-ray diffraction in thermally treated human tooth samples.

The crystalline indexes obtained through infrared spectroscopy (CI) and X-ray diffraction (CI) were used to analyze the structural changes of dentin and enamel in human teeth when subjected to heat treatments between room temperature (25 °C) to 1200 °C in atmospheric air and argon. Thermogravimetric (TGA) and differential scanning calorimetry (DSC) analyses of sound powders were also used to support the analysis. As the temperature increased, the CI increased exhibiting a behavior like that of the crystal grain size, and the CI increased until the β-TCP phase appeared.

The SEM electron-mirror effect in human tooth and synthetic hydroxyapatite samples.

The characteristics of the electron-mirror effect (EME) image depend on both the scanning electron microscope parameters and the sample's physical properties. The behavior of human tooth (dentin and enamel) and synthetic hydroxyapatite samples submitted to the EME procedure is presented in this work. Polyethylene terephthalate (PET) and epoxy resin, two good EME producers, were used for comparison.

Aberration-Corrected Transmission Electron Microscopic Study of the Central Dark Line Defect in Human Tooth Enamel Crystals.

Angstrom resolution images of human tooth enamel (HTE) crystallites were obtained using aberration-corrected high-resolution transmission electron microscopy and atomic-resolution scanning transmission electron microscopy in the modes of bright field, annular dark field, and high-angle annular dark-field. Images show that the central dark line (CDL) defect observed around the center of the HTE crystals is a site for caries formation in the HTE and has a thickness of ~0.2 nm.

Helical Growth of Ultrathin Gold-Copper Nanowires.

In this work, we report the synthesis and detailed structural characterization of novel helical gold-copper nanowires. The nanowires possess the Boerdijk-Coxeter-Bernal structure, based on the pile up of octahedral, icosahedral, and/or decahedral seeds. They are self-assembled into a coiled manner as individual wires or into a parallel-ordering way as groups of wires.

Gold-copper nanostars as photo-thermal agents: synthesis and advanced electron microscopy characterization.

Nanoalloys have emerged as multi-functional nanoparticles with applications in biomedicine and catalysis. This work reports the efficient production and the advanced transmission electron microscopy characterization of gold-copper pentagonal nanostars. The morphology of the branches is controlled by the adequate choice of the capping agent.

Wettability modification of human tooth surface by water and UV and electron-beam radiation.

The wettability of the human tooth enamel and dentin was analyzed by measuring the contact angles of a drop of distilled water deposited on the surface. The samples were cut along the transverse and longitudinal directions, and their surfaces were subjected to metallographic mirror-finish polishing. Some samples were also acid etched until their microstructure became exposed.

Scanning Electron Microscopic Study on the Fibrillar Structures within Dentinal Tubules of Human Dentin.

Introduction: Pulp biology is central to the whole tooth, and knowledge on its microstructure is changing with new studies. This study presents certain microfibrillar structures found within the dentin tubules of human teeth connecting dentin tubules and odontoblastic processes.

Methods: We analyzed the crowns of 30 noncarious, human teeth.

Evidence of noncentrosymmetry of human tooth hydroxyapatite crystals.

Herein, we investigate human single hydroxyapatite crystals (enamel and dentine) by convergent-beam electron diffraction (CBED) and automated electron-diffraction tomography (ADT). The CBED pattern shows the absence of the mirror plane perpendicular to the c axis leading to the P63 space group instead of the P63 /m space group considered for larger-scale crystals, this is confirmed by ADT. This experimental evidence is of prime importance for understanding the morphogenesis and the architectural organization of calcified tissues.

XRD and FTIR crystallinity indices in sound human tooth enamel and synthetic hydroxyapatite.

The crystallinity index (CI) is a measure of the percentage of crystalline material in a given sample and it is also correlated to the degree of order within the crystals. In the literature two ways are reported to measure the CI: X-ray diffraction and infrared spectroscopy. Although the CI determined by these techniques has been adopted in the field of archeology as a structural order measure in the bone with the idea that it can help e.

Presence of matrix vesicles in the body of odontoblasts and in the inner third of dentinal tissue: a scanning electron microscopic study.

Objectives: The aim of this report is to present the results of a scanning electron microscopic study on the presence of matrix vesicles (MVs) found in human dentine.

Study Design: Dentin tissue from 20 human bicuspids was analyzed by means of scanning electron microscopy.

Results: MVs were found as outgrowths of the cellular membrane of the odontoblastic body, the more proximal portion of the odontoblastic process before entering the dentinal tubule and in the odontoblastic process within the inner third of the dentin.

Scanning electron micrographic features of a giant submandibular sialolith.

To recognize recently appearing mineralization phenomena, one must study the external surface of the sialoliths, since it is not possible to study them in the central portions of sialoliths. The authors examined the external surface of a sialolith by scanning electron microscopy and analyzed its microstructures. The study revealed the presence of numerous microstructures of different shapes (nodular, laminar, reticular, microgranular, and multinodular) and variable size arranged in a haphazard fashion.

Elaboration and structural analysis of aquasomes loaded with indomethacin.

The aim of this study was to prepare nanoparticles in form of aquasomes with Indomethacin as a low solubility drug mode. Aquasomes charged with Indomethacin were obtained through the formation of an inorganic core of calcium phosphate covered with a Lactose film and further adsorption of the Indomethacin. Structural analyses, particle size, and morphology were evaluated by X-ray powder diffractometry, transmission electron microscopy, and scanning electron microscopy.

STEM-HAADF electron microscopy analysis of the central dark line defect of human tooth enamel crystallites.

When human tooth enamel is observed with the Transmission Electron Microscope (TEM), a structural defect is registered in the central region of their nanometric grains or crystallites. This defect has been named as Central Dark Line (CDL) and its structure and function in the enamel structure have been unknown yet. In this work we present the TEM analysis to these crystallites using the High Angle Annular Dark Field (HAADF) technique.

Human Cementum Protein 1 induces expression of bone and cementum proteins by human gingival fibroblasts.

We recently presented evidence showing that a human cementoblastoma-derived protein, named Cementum Protein 1 (CEMP1) may play a role as a local regulator of cementoblast differentiation and cementum-matrix mineralization. This protein was shown to be expressed by cementoblasts and progenitor cells localized in the periodontal ligament. In this study we demonstrate that transfection of CEMP1 into human gingival fibroblasts (HGF) induces mineralization and expression of bone and cementum-matrix proteins.

Crystal structure characterization of nautilus shell at different length scales.

In this work, we studied the shell structure of the Nautilus pompilius Linnaeus by using analytical techniques of scanning (SEM) and transmission electron microscopy (TEM) and X-ray diffraction. The main objective of this study is the structural characterization of Nautilus shell at different length levels, from micron to nano-scale. The results were also used to try to determine the shell structure mechanism of formation.

Anti-cementoblastoma-derived protein antibody partially inhibits mineralization on a cementoblastic cell line.

The effect of human anti-cementoblastoma-derived protein antibody during cementogenesis in vitro was investigated by using human cementoblastoma-derived cells. Cultures treated with 5 microg/ml of CP antibody from day 1 to day 15 revealed a significant decrease in alkaline phosphatase activity (ALP) 40% (p < 0.005), 44% (p < 0.