Ultraviolet light

About: Ultraviolet light is a research topic. Over the lifetime, 49494 publications have been published within this topic receiving 843151 citations.

Protein Denaturation and the Properties of Protein Groups

Abstract: Publisher Summary The chapter discusses (1) the properties of protein groups, how they are influenced by denaturation and other factors, and how these influences can be explained, (2) the reversibility of denaturation, and (3) the all-or-none character of denaturation. The conversion of native protein that is soluble at its isoelectric point to denatured protein that is insoluble at the isoelectric point in the absence of reagents such as urea can be brought about not only by heat but also by surface action, ultraviolet light, high pressure, organic solvents such as alcohol, and, in general, those reagents that can dissolve coagulated protein— such as acid, alkali, urea, guanidine hydrochloride, detergents, and salicylate. A protein denatured so that it becomes insoluble at its isoelectric point in pure water or dilutes salt solutions is also changed in a number of other properties. Groups such as SH, S-S, and tyrosine give certain characteristic reactions more readily in the denatured than in the native form of many proteins. Some of the specific properties of individual native proteins are lost when the protein is denatured. When a molecule of protein is denatured it opens up and, as a result, changes its shape radically. Although this general change in structure is now well established, it is not possible at the present stage of knowledge of protein structure to define denaturation exactly by means of a detailed description of the change in structure of the protein molecule.

Near-infrared upconversion-activated CRISPR-Cas9 system: A remote-controlled gene editing platform.

Abstract: As an RNA-guided nuclease, CRISPR-Cas9 offers facile and promising solutions to mediate genome modification with respect to versatility and high precision. However, spatiotemporal manipulation of CRISPR-Cas9 delivery remains a daunting challenge for robust effectuation of gene editing both in vitro and in vivo. Here, we designed a near-infrared (NIR) light–responsive nanocarrier of CRISPR-Cas9 for cancer therapeutics based on upconversion nanoparticles (UCNPs). The UCNPs served as “nanotransducers” that can convert NIR light (980 nm) into local ultraviolet light for the cleavage of photosensitive molecules, thereby resulting in on-demand release of CRISPR-Cas9. In addition, by preparing a single guide RNA targeting a tumor gene (polo-like kinase-1), our strategies have successfully inhibited the proliferation of tumor cell via NIR light–activated gene editing both in vitro and in vivo. Overall, this exogenously controlled method presents enormous potential for targeted gene editing in deep tissues and treatment of a myriad of diseases.

Topical L-ascorbic acid : Percutaneous absorption studies

Abstract: background. Reactive oxygen species generated by ultraviolet light result in photocarcinogenic and photoaging changes in the skin. Antioxidants protect skin from these insults. objective. This study defines formulation characteristics for delivering L-ascorbic acid into the skin to supplement the skin’s natural antioxidant reservoir. methods. L-ascorbic acid or its derivatives were applied to pig skin. Skin levels of L-ascorbic acid were measured to determine percutaneous delivery. results. L-ascorbic acid must be formulated at pH levels less than 3.5 to enter the skin. Maximal concentration for optimal percutaneous absorption was 20%. Tissue levels were saturated after three daily applications; the half-life of tissue disappearance was about 4 days. Derivatives of ascorbic acid including magnesium ascorbyl phosphate, ascorbyl-6-palmitate, and dehydroascorbic acid did not increase skin levels of L-ascorbic acid. conclusions. Delivery of topical L-ascorbic acid into the skin is critically dependent on formulation characteristics.