Newly emerging and innovative technologies are converging, so that one new technology can enhance the use of the other, and there are benefits of the convergence that are greater than the sum of its parts. Convergence is a fruitful area for addressing some global crises, and in particular the emerging food crisis. The global population is now over seven billion people and will reach 9.3 billion by 2050, pushing up food demand by about 60%. Food irradiation technology and polymer nanomaterials1 for food packaging are developing in parallel. Both of these technologies have specific benefits and risks of their own. Unanswered questions in the literature are about the possibilities of combining these technologies, how the benefit/risk balance is altered, and whether such a convergence is publicly acceptable. This paper begins to gathering and relating basic facts that may assist in seeking answers to these questions. It overviews some of the technical possibilities and the benefit/risk issues involved in the possible convergence of nanomaterials, polymer-packaging materials and food irradiation.
Artificially synthesized hydroxyapatite (HAp) exhibits excellent biocompatibility with various kinds of cells and tissues, making it an ideal candidate for orthopedic and dental applications. HAp-based nanocomposites with polymers, metals, and other kinds of bioceramics have developed in order to improve the mechanical strength of HAp. This review is focused on providing a summary of existing knowledge and recent advances on fabrication methods of HAp nanocomposites.
Composite resin (CR) is used in vivo as a root perforation sealer and as a retrograde obturation material following apicoectomy, but it does not possess adequate biocompatibility. Effective biological modification of the CR surface is thus needed to improve its biocompatibility. Carbon nanotubes (CNTs) are a type of nanocarbon material formed from cylindrical graphene sheets with a diameter of about 10 to 200 nm. CNTs have garnered attention for useful properties such as promoting cell adhesion and proliferation. The present study evaluated cell adhesion and proliferation on CR discs coated with CNTs. CR discs were coated by immersion in a dispersion of CNTs (Nanocyl NC7000, 9.5 nm diameter). The CNT coating was then observed with a scanning electron microscope (SEM) to investigate its surface properties. The effects of CNT coating were also investigated by conducting cell culture assay using osteoblasts. The coating process enabled CNTs to adhere to the resin surface, resulting in good adhesion and spreading of the osteoblasts that indicated a high level of cell proliferation. The study findings showed that coating the surface of CRs with CNTs improved their biocompatibility.
Orthodontic adhesives are usually colorless and transparent for aesthetic purposes. However, making such adhesives fluorescent is one of the most effective solutions to make them visible to ensure safe and complete removal after orthodontic treatments. Trivalent europium ions were doped into yttrium oxides by a homogeneous precipitation method. The particles were synthesized via a homogeneous precipitation method and had a narrow size distribution (200–300 nm) and showed sharp crystallinity independent of the starting concentration of Eu3+. The strongest emission and absorption peaks were identified at 611 nm and 396 nm, respectively. In this study, 8 mol% was confirmed to be the optimum doping concentration. The emission intensity of phosphor containing PMMA adhesives was appreciably weak even when the concentration of phosphors was 10 wt%. It may be attributed to the clustering of the particles or a multiphonon relaxation process owing to organic groups in the polymer. We conclude that the crystalline Y2O3:Eu3+ particles could be applicable for the development of fluorescent orthodontic adhesives.
Since one of the potential applications of titanium oxide nano-tubes (TNT) is to photodynamic therapy (PDT), the effects of reactive oxygen species (ROS) generated by TNT irradiated with ultraviolet (UV) rays were evaluated in HeLa cells.
The microstructures of cells incubated in TNT-containing medium were observed using scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX), and the adherence of TNT to these cells was confirmed. An oxidative stress fluorescence probe was then used to visualize oxidative stress in HeLa cells, and revealed that the ROS generated by TNT led to oxidative stress in HeLa cells. A flow cytometric analysis was performed to characterize the cell status and distinguish between viable and unviable cells. Polyethylene glycol (PEG) modifications to the surfaces of TNT effectively facilitated adherence to cells, and the UV irradiation of HeLa cells during their incubation in culture medium containing PEG-modified TNT induced oxidative stress, thereby suppressing DNA repair.
Carcinogens are mostly mutagens that cause genetic abnormalities as cancer initiators. Multi-walled carbon nanotubes (MWCNTs) have been demonstrated to be mutagenic in many animal experiments. In the present study, we examined the mutagenicity of MWCNTs using an umu test for mutagenicity screening and the leakage of mutagens from MWCNTs, secondary to the exposure of cultured cells to MWCNTs, demonstrating no mutagenicity, although some values were nearly positive.
The purpose of this study was to investigate the effect of gliding arc discharge non-thermal atmospheric pressure plasma with N2 carrier gas on surface chemical modification for adhesion improvement. The shear bond strength between the orthodontic adhesive resin and plasma-treated stainless steel surface improved slightly, although the surface free energy of the stainless steel samples increased from 73.6 mJ·m−2 to 112.9 mJ·m−2 mainly due to an increase of the dipole component (γSp) and partially due to an increase of the hydrogen bond component (γSh). This is partly because the metastability of the stainless steel surface was stabilized by immediate hydration or adsorption of water on the highly hydroxylated stainless steel surfaces. However, surface cleaning and hydroxylating efficacy of the handheld device was determined to be superior to those of other surface cleaning procedures, particularly in terms of intraoral applications. The technique may be potentially employed in establishing M-S coordinate bonds in dental precious metals and related alloys.