Strategies for Controlling the Spatial Orientation of Single Molecules Tethered on DNA Origami Templates Physisorbed on Glass Substrates: Intercalation and Stretching.

Nanoarchitectural control of matter is crucial for next-generation technologies. DNA origami templates are harnessed to accurately position single molecules; however, direct single molecule evidence is lacking regarding how well DNA origami can control the orientation of such molecules in three-dimensional space, as well as the factors affecting control. Here, we present two strategies for controlling the polar (θ) and in-plane azimuthal (ϕ) angular orientations of cyanine Cy5 single molecules tethered on rationally-designed DNA origami templates that are physically adsorbed (physisorbed) on glass substrates. By using dipolar imaging to evaluate Cy5's orientation and super-resolution microscopy, the absolute spatial orientation of Cy5 is calculated relative to the DNA template. The sequence-dependent partial intercalation of Cy5 is discovered and supported theoretically using density functional theory and molecular dynamics simulations, and it is harnessed as our first strategy to achieve θ control for a full revolution with dispersion as small as ±4.5°. In our second strategy, ϕ control is achieved by mechanically stretching the Cy5 from its two tethers, being the dispersion ±10.3° for full stretching. These results can in principle be applied to any single molecule, expanding in this way the capabilities of DNA as a functional templating material for single-molecule orientation control. The experimental and modeling insights provided herein will help engineer similar self-assembling molecular systems based on polymers, such as RNA and proteins.

[Effect of nanostructured lipid carriers (NLCs) in improving stability of essential oils and its application].

Essential oils are easy to cause oxidative damage, chemical transformation or polymerization, and have some intrinsic problems, such as instability, low water solubility and low bioavailability, which restrict their application in the fields of product development. Nanostructured lipid carriers(NLCs) can overcome some of the restrictions of other colloidal carriers, such as emulsions, liposomes, polymer nanoparticles and solid lipid nanoparticles. NLC is an efficient and stable delivery system for bioactive substances. With unique lipid properties(mixture of solid and liquid lipid), it can overcome the disadvantages of essential oils and protect them from adverse environments, thus improving the stability, bioavailability and safety of essential oils, and achieve sustained release and controlled release. In EOs-NLCs system, essential oils, as special liquid lipid with biological activities and medicinal properties, can fully play the role of medicine-adjuvant integration by changing the structural characteristics of mixed lipid. Based on the development of nanocarriers system, this paper introduces the composition and structural characteristics of EOs-NLCs, and clarifies how to improve the stability of essential oils based on the effects of NLCs on physical and chemical properties, physical stability and release of active components of essential oils. In addition, it also introduces the application of the system in the fields of pharmaceutical, food, cosmetics and skin care products. This review aims to provide some references for improving the stability of essential oils and their applications by using NLCs.