Grafting from polymerization was used to synthesize nano-titania/polyurethane (nTiO(2)/polyurethane) composite coatings, where nTiO(2) was chemically attached to the backbone of the polyurethane polymer matrix with a bifunctional monomer, 2,2-bis(hydroxymethyl) propionic acid (DMPA). This bifunctional monomer can coordinate to nTiO(2) through an available -COOH group, with two available hydroxyl groups that can react with diisocyanate terminated pre-polyurethane through step-growth polymerization. The coordination reaction was monitored by FTIR and TGA, with the coordination reaction found to follow first order kinetics. After step-growth polymerization, the polyurethane nanocomposites were found to be stable on standing with excellent distribution of Ti in the polymer matrix without any significant agglomeration compared to simple physical mixtures of nTiO(2) in the polyurethane coatings. The functionalized nTiO(2)-polyurethane composite coatings showed excellent antibacterial activity against gram-negative bacteria Escherichia coli; 99% of E. coli were killed within less than one hour under solar irradiation. Self-cleaning was also demonstrated using stearic acid as a model for 'dirt'.

Background: Immuno-modulatory effects of ginseng, including both immuno-stimulatory and immuno-suppressive effects, have been widely reported. This study aims to determine whether the paradoxical immuno-modulatory effect is related to unique phytochemical profiles of different North American (NA) ginseng, namely aqueous (AQ) and alcoholic (ALC) extracts. Methods: AQ and ALC extracts were prepared and their immuno-bioactivity were studied in vitro in murine macrophages (Raw 264.7) through measuring the direct stimulatory production of pro-inflammatory mediator and cytokines as well as the suppression of lipopolysaccharide (LPS)-stimulatory response by the two extracts. Gel permeation chromatography was used to fractionate and isolate phytochemicals for characterization of ginseng extracts. Results: AQ extract up-regulated the production of nitric oxide (NO), tumour necrosis factor-α (TNF-α) and interleukin-6 (IL-6) while ALC extract did not. ALC extract but not AQ extract suppressed LPS-induced macrophage NO and TNF-α production. These immuno-stimulatory and suppressive effects were exhibited at similar extract concentrations. Moreover, the macrophage-stimulating activity of the AQ extract was inhibited in the presence of ALC extract. Fractionation of AQ extract revealed the presence of two major peaks at 230 nm with average molecular weights of 73,000 and 37,000 Da. The first fraction had similar elution volume as the crude polysaccharide (PS) fraction isolated from the AQ extract, and it was the only bioactive species. Parallel fractionation study of ALC extract yielded similar elution profiles; however, both sub-fractions were devoid of PS. Fraction I of the ALC extract suppressed LPS-induced NO production dose-dependently. Conclusion: ALC extract of NA ginseng, which was devoid of PS, was immuno-inhibitory whereas the AQ extract, which contained PS, was immuno-stimulatory. These extract-related anti-inflammatory and pro-inflammatory effects may be considered as the Yin and Yang actions of ginseng.

Silicon Quantum Dots (SQDs) have recently attracted great interest due to their excellent optical properties, low cytotoxicity, and ease of surface modification. The size of SQDs and type of ligand on their surface has a great influence on their optical properties which is still poorly understood. Here we report the synthesis and spectroscopic studies of three families of unreported SQDs functionalized by covalently linking to the aromatic fluorophores, 9-vinylphenanthrene, 1-vinylpyrene, and 3-vinylperylene. The results showed that the prepared functionalized SQDs had a highly-controlled diameter by HR-TEM, ranging from 1.7–2.1 nm. The photophysical measurements of the assemblies provided clear evidence for efficient energy transfer from the fluorophore to the SQD core. Fӧrster energy transfer is the likely mechanism in these assemblies. As a result of the photogenerated energy transfer process, the emission color of the SQD core could be efficiently tuned and its emission quantum efficiency enhanced. To demonstrate the potential application of the synthesized SQDs for bioimaging of cancer cells, the water-soluble perylene- and pyrene-capped SQDs were examined for fluorescent imaging of HeLa cells. The SQDs were shown to be of low cytotoxicity