NLC-Based Sunscreen Formulations with Optimized Proportion of Encapsulated and Free Filters Exhibit Enhanced UVA and UVB Photoprotection.

The topical use of sunscreens is recommended for avoiding the damaging effects of UV radiation. However, improvements are still needed in the existing products to enhance their photoprotection effectiveness and safety. This involves minimizing the use of chemical UV filters while providing enhanced and prolonged photoprotection. This work investigated novel sunscreen formulations and their UV protection effects by encapsulating Uvinul® A, Tinosorb® S, and Uvinul® T150 into nanostructured lipid carriers (NLCs) based on bacuri butter and raspberry seed oil. First, the impact of critical formulation and process parameters on NLCs' particle size was evaluated using a 22 Face Centered Central Composite Design. Then, formulations were evaluated in terms of critical quality factors, in vitro skin permeation, and in vitro and in vivo photoprotection activities. The developed NLCs-containing formulations exhibited appropriate size (122-135 nm), PdI (<0.3), encapsulation efficiency (>90%), and drug content (>80%), which were preserved for at least 90 days under different stability conditions. Moreover, these NLCs-based formulations had equivalent skin permeation to emulsion-based controls, and the addition of NLCs into sunscreen cream bases in the optimum proportion of 20% (w/w) resulted in enhanced UVA and UVB photoprotection levels, despite a 10% reduction in the total filters content. Altogether, these results describe the application of nanoencapsulated organic UV filters in innovative sunscreen formulations to achieve superior photoprotection and cosmeceutical properties.

Degradable and colloidally stable zwitterionic-functionalized silica nanoparticles.

Aim: This work is focused on obtaining degradable mesoporous silica nanoparticles (DMSNs) which are able to maintain their colloidal stability in complex biological media. Materials & methods: DMSNs were synthesized using different ratios of disulfide organosilane (degradable structural moiety) and further functionalized with sulfobetaine silane (SBS) to enhance colloidal stability and improve biological compatibility. Results: There was a clear trade-off between nanoparticle degradability and colloidal stability, since full optimization of the degradation process generated unstable particles, while enhancing colloidal stability resulted in poor DMSNs degradation. It was also shown that acidic pH improved particle degradation which is commonly triggered by reduction stimulus. Conclusion: A chemical composition window was found where DMSNs presented satisfactory colloidal stability in biologically relevant medium, meaningful degradation profiles and high biocompatibility.

New strategy to obtain high surface area anatase nanotube/AuNP photocatalyst.

Anatase nanotubes with high surface area (ca. 350 m2 g-1), containing gold nanoparticles, were successfully obtained from trititanate nanotubes, prepared by a template-free hydrothermal method, and calcined at 450 °C. The high surface area and tubular morphology were attained due to the presence of ionic silsesquioxane, which acts as anti-sintering agent for titania during calcination process, by forming a thin silica coating between anatase nanotubes. Additionally, the ionic silsesquioxane also acts as stabilizing and adhesion agent for gold nanoparticles on the surface of anatase nanotubes. The influence of the ionic silsesquioxane on the morphological and textural properties of anatase nanotubes was studied in three different moments during the synthesis: before, after and before/after nanotubes were rolled up. The photocatalytic activity of the nanotube samples was evaluated by hydrogen generation showing remarkable enhancement in hydrogen production and stability of catalyst when compare with the bare anatase sample and commercial P-25.

Silver nanoparticle-ionic silsesquioxane: a new system proposed as an antibacterial agent.

Spherical silver nanoparticles with an average size of ca. 5 nm were synthesized in aqueous medium using a charged silsesquioxane containing a quaternary ammonium group, the bridged 1,4-diazoniabicyclo[2.2.2]octane nitrate, as a stabilizer and size controller. For the first time this system was synthesized and applied as an antibacterial agent and its activity was confirmed with excellent results. The new system shows high stability, which can be confirmed by the unchanged UV-Vis band even one year later. The magnitude of the zeta-potential (ζ) (+24.7 mV) indicated electrostatic contribution for the silver nanoparticles stability and the signal showed that the nanoparticles have a positively charged surface. In vitro antibacterial tests were performed against E. coli, P. aeruginosa and S. aureus bacteria, and the minimum concentrations of silver in the nanoparticle form for complete inhibition of bacteria were 0.60, 1.1 and 2.0 µg mL-1, respectively. These values are very low when compared to the previous reports, making this system very promising. The cytotoxicity assay showed that these silver nanoparticles are safe for mammalian cells at the studied concentrations.