Minimally invasive image-guided therapy for inoperable hepatocellular carcinoma: What is the evidence today?

Hepatocellular carcinoma (HCC) is a primary malignant tumor of the liver that accounts for an important health problem worldwide. Only 10–15% of HCC patients are suitable candidates for hepatic resection and liver transplantation due to the advanced stage of the disease at time of diagnosis and shortage of donors. Therefore, several minimally invasive image-guided therapies for locoregional treatment have been developed. Tumor ablative techniques are either based on thermal tumor destruction, as in radiofrequency ablation, cryoablation, microwave ablation, laser ablation and high-intensity focused ultrasound, or chemical tumor destruction, as in percutaneous ethanol injection. Image-guided catheter-based techniques rely on intra-arterial delivery of embolic, chemoembolic or radioembolic agents. These minimally invasive image-guided therapies have revolutionized the management of inoperable HCC. This review provides a description of all minimally invasive image-guided therapies currently available, an up-to-date overview of the scientific evidence for their clinical use, and thoughts for future directions

Acceleration of a Nanomotor: Electronic Control of the Rotary Speed of a Light-Driven Molecular Rotor

Facing the challenge to construct nanoscale machines, it has been noted that molecular motors stand out as essential components to provide power to such systems. The diversity of fascinating biological motors, such as the kinesin or myosin linear and ATP-ase rotary motor systems, has been a source of inspiration for the development of artificial molecular mechanical devices (such as switches, shuttles, and muscles) and a variety of elegant rotor systems. The sterically overcrowded alkenes prepared in our laboratories provided the basis for a light-driven motor. Unidirectional rotation is achieved by a combination of a photochemically mediated cis-trans isomerization followed by an irreversible thermal isomerization. The motor described here is based on the second-generation light-driven unidirectional molecular motors 1. A limitation of these molecular motors proved to be their low rotary speed. A major goal of our molecular motor program is to substantially lower the Gibbs energy of activation of the thermal isomerization, the rate-determining step for the 360° rotation around the central double bond in these overcrowded alkenes. Thus far, all attempts to decrease the thermal isomerization barriers have involved structural modifications in order to diminish steric interactions around the fjord region of the molecules. This has been achieved by the introduction of smaller-sized atoms in 1 at bridging position X or using smaller rings appended to the central alkene.

Increased Speed Of Rotation For The Smallest Light-driven Molecular Motor: Supporting information CIF-file for C28H24

In this paper we present the smallest artificial light-driven molecular motor consisting of only 28 carbon and 24 hydrogen atoms. The concept of controlling directionality of rotary movement at the molecular level by introduction of a stereogenic center next to the central olefinic bond of a sterically overcrowded alkene does not only hold for molecular motors with six-membered rings, but is also applicable to achieve the unidirectional movement for molecular motors having five-membered rings. Although X-ray analyses show that the five-membered rings in the cis-and trans-isomer of the new molecular motor are nearly flat, the energy differences between the (pseudo-)diaxial and (pseudo-)diequatorial conformations of the methyl substituents in both isomers are still large enough to direct the rotation of one-half of the molecule with respect to the other half in a clockwise fashion. The full rotary cycle comprises four consecutive steps: two photochemical isomerizations each followed by a thermal helix inversion. Both photochemical cis- transisomerizations proceed with a preference for the unstable diequatorial isomers over the stable diaxial isomers. The thermal barriers for helix inversion of this motor molecule have decreased dramatically compared to its six-membered ring analogue, the half-life of the fastest step being only 18 s at room temperature.

Light-Driven Molecular Motors

Molecular motors can be defined as molecules that are able to convert any type of energy input (a fuel) into controlled motion. These systems can be categorized into linear and rotary motors, depending on the motion induced. This brief account will discuss the state of affairs of the research on light-driven rotary molecular motors.

Controlling the color of cholesteric liquid-crystalline films by photoirradiation of a chiroptical molecular switch used as dopant

Using thin films of a cholesteric mixture of acrylates 2 and 3 doped with the chiroptical molecular switch (M)-trans-1, photo-control of the reflection color between red and green is possible. This doped liquid-crystal (LC) film can be used for photoinduced writing, color reading, and photoinduced locking (via polymerization) of chiral, optically written information