Effect of a Stannous Fluoride Dentifrice on Biofilm Composition, Gene Expression and Biomechanical Properties.

An in situ study was conducted to examine the mode of action of a 0.454% stannous fluoride (SnF2)-containing dentifrice in controlling the composition and properties of oral biofilm. Thirteen generally healthy individuals participated in the study. Each participant wore an intra-oral appliance over a 48-h period to measure differences in the resulting biofilm's architecture, mechanical properties, and bacterial composition after using two different toothpaste products. In addition, metatranscriptomics analysis of supragingival plaque was conducted to identify the gene pathways influenced. The thickness and volume of the microcolonies formed when brushing with the SnF2 dentifrice were dramatically reduced compared to the control 0.76% sodium monofluorophosphate (MFP)-containing toothpaste. Similarly, the biophysical and nanomechanical properties measured by atomic force microscopy (AFM) demonstrated a significant reduction in biofilm adhesive properties. Metatranscriptomic analysis identified pathways associated with biofilm formation, cell adhesion, quorum sensing, and N-glycosylation that are significantly downregulated with SnF2. This study provides a clinically relevant snapshot of how the use of a stabilized, SnF2 toothpaste formulation can change the spatial organization, nanomechanical, and gene expression properties of bacterial communities.

Holistic approach to visualize and quantify collagen organization at macro, micro, and nano-scale.

BACKGROUND: There is scarcity of imaging and image processing techniques for accurate discrimination and quantitation of the dermal extracellular matrix (ECM), primarily collagen. The aim of this study was to develop and demonstrate a holistic imaging and image processing approach to visualize and quantify collagen remodeling at the macro-, micro- and nano-scale using histochemical imaging, Reflectance Confocal Microscopy (RCM), and Atomic Force Microscopy (AFM), respectively. MATERIAL AND METHODS: For proof-of-concept, a commercial anti-aging product known to induce collagen neo-synthesis and re-organization was tested ex vivo on human skin biopsies from two aged females. RESULTS: Relative to untreated skin, collagen fibers (RCM) and fibrils (AFM) were longer and aligned after treatment. The content of collagen and elastin (histochemical imaging and ELISA) statistically improved after treatment. CONCLUSION: Based on our findings, we can conclude: (1) AFM, RCM, and histochemical imaging can accurately discriminate collagen from other ECM components in the skin and (2) the image processing methods can enable quantitation and hence capture small improvements in collagen remodeling after treatment (commercial cosmetic product with collagen organizer technology as proof-of-concept). The reported holistic imaging approach has direct clinical implications for scientists and dermatologists to make quick, real-time, and accurate decisions in skin research and diagnostics.

Identification of distinct nanoparticles and subsets of extracellular vesicles by asymmetric flow field-flow fractionation.

The heterogeneity of exosomal populations has hindered our understanding of their biogenesis, molecular composition, biodistribution and functions. By employing asymmetric flow field-flow fractionation (AF4), we identified two exosome subpopulations (large exosome vesicles, Exo-L, 90-120 nm; small exosome vesicles, Exo-S, 60-80 nm) and discovered an abundant population of non-membranous nanoparticles termed 'exomeres' (~35 nm). Exomere proteomic profiling revealed an enrichment in metabolic enzymes and hypoxia, microtubule and coagulation proteins as well as specific pathways, such as glycolysis and mTOR signalling. Exo-S and Exo-L contained proteins involved in endosomal function and secretion pathways, and mitotic spindle and IL-2/STAT5 signalling pathways, respectively. Exo-S, Exo-L and exomeres each had unique N-glycosylation, protein, lipid, DNA and RNA profiles and biophysical properties. These three nanoparticle subsets demonstrated diverse organ biodistribution patterns, suggesting distinct biological functions. This study demonstrates that AF4 can serve as an improved analytical tool for isolating extracellular vesicles and addressing the complexities of heterogeneous nanoparticle subpopulations.

The Effect of Cage Shape on Nanoparticle-Based Drug Carriers: Anticancer Drug Release and Efficacy via Receptor Blockade Using Dextran-Coated Iron Oxide Nanocages.

Although a range of nanoparticles have been developed as drug delivery systems in cancer therapeutics, this approach faces several important challenges concerning nanocarrier circulation, clearance, and penetration. The impact of reducing nanoparticle size on penetration through leaky blood vessels around tumor microenvironments via enhanced permeability and retention (EPR) effect has been extensively examined. Recent research has also investigated the effect of nanoparticle shape on circulation and target binding affinity. However, how nanoparticle shape affects drug release and therapeutic efficacy has not been previously explored. Here, we compared the drug release and efficacy of iron oxide nanoparticles possessing either a cage shape (IO-NCage) or a solid spherical shape (IO-NSP). Riluzole cytotoxicity against metastatic cancer cells was enhanced 3-fold with IO-NCage. The shape of nanoparticles (or nanocages) affected the drug release point and cellular internalization, which in turn influenced drug efficacy. Our study provides evidence that the shape of iron oxide nanoparticles has a significant impact on drug release and efficacy.

Amino acid catalyzed biomimetic preparation of tin oxide-germania nanocomposites and their characterization.

The efficiency of growth of nanocrystalline tin oxide-germania nanocomposites at room temperature was investigated in the presence of the amino acids arginine, histidine, and lysine under varying conditions. The preparation of tin oxide nanoparticles under similar conditions was also examined. It was observed that of the three amino acids, arginine was the most efficient and formed higher yields of the products. Calcination of the products led to crystalline materials. The growth was carried out using a biological approach under mild conditions at room temperature. The morphology and the crystallinity of the products were examined by transmission electron microscopy and atomic force microscopy. The optical properties of the nanocomposites were characterized by fluorescence, and ultraviolet-visible spectroscopy. The nitrogen adsorption studies indicate that the nanocomposites obtained were mesoporous in nature. The nanocomposites exhibited high BET surface area. Such materials could be potentially useful for the development of improved gas sensor devices and optical devices.