LC today: industry & applications news October 2016

LC controlled drug delivery

Vesicles have gained popularity as a system for drug delivery. Usually made up of a lipid bilayer membrane, they encapsulate an aqueous solution and can therefore be used as a container for drugs. Controlled delivery of the contents from such a system is important for ensuring the drug reaches the correct location, or that it is released over the correct time period. Researchers at the University of Chicago’s Institute for Molecular Engineering have now developed a novel use of a liquid crystal (LC) medium to control the deformation of a vesicle [1]. Not only can this be used as a novel means of controlling drug delivery without direct contact of the vesicle, but the technique could have many other applications in biology or materials science.

The group from Chicago proposed the mechanism as a result of advanced computer models. They showed that LC molecules forming a nematic phase, in which all the molecules tend to align in the same direction, could be used to deform a spherical vesicle into an elongated shape. This model was then confirmed by the experimental observation of the deformation of a giant unilamellar vesicle (GUV) in such a system. When placed in solutions of lyotropic chromonic LC, the GUV would exhibit a spherical shape, approximately 5 μm in diameter, while in an isotropic solution, whereas it would take on a spindle shape in a nematic solution as a result of the elastic forces [2].

The mechanism is of interest as the elastic and anchoring properties of the LC can be used to modify the deformation. The temperature dependence of the LC phases could also be exploited to produce a system which would only produce the deformation under a certain temperature range. The head of the research group, Professor Juan de Pablo, suggests that the technique could be used as a way to squeeze the vesicle and eject the contents without direct contact to the system.

Micro-pumping for lab-on-chip

Lab-on-chip devices often suffer the problem of not entirely fitting into the limited space that their name suggests. While these exciting devices are capable of performing all manners of testing and diagnostics in an extremely confined space, the difficulty of miniaturising certain components has prevented some devices from realising their chip-like potential. One such component is the pumping and tubing system required to move fluids around such a micro-lab. Light-driven proposals have previously fallen short; however, new work from Fudan University Shanghai has devised a solution by fabricating specially designed tubing from a liquid crystal polymer (LCP) [3,4].

The tubular material acts as a microactuator and can be used to precisely move small amounts of liquid around, using the response of the material to light as the driving force. The response of the material aims to mimic that of blood-carrying arteries inside the human body. Being able to drive such a response with light allows the researchers to precisely move a volume of fluid around the system over a large distance and in a controlled manner.

The LCP designed for the task utilises an azobenzene component to achieve the desired properties: ensuring the material assembles into layers and also providing a response to light. The material, upon exposure to blue light, exhibits an expansion. This causes any liquid inside the cavity to move away from the illuminated segment, towards a region of lower light intensity as a result of differences in surface tension. This allowed the team to move slugs of liquid around the system at controllable velocities, and even up inclines, as reported in Nature [5].

The team have been able to fabricate a series of different structures out of the LCP, as well as move a variety of liquids inside it. While promising, there is still much work required before the technology is seen in lab-on-chip devices – such as a precise method for light delivery – but the potential uses could prove plentiful.

Merck invests in LC windows

Merck, one of the leading companies in the LC market, announced in August that they would be investing €15 million into LC-based smart window technology [6]. This follows on from the company’s acquisition of Dutch company, Peer+, in 2014, with whom they had collaborated on the technology since 2011. Merck hope to begin manufacturing the switchable glass by the end of 2017.

The smart windows allow switching not only between transparent and opaque states, but also the ability to change through a range of opacities. Varying the light transmitted through a window can vastly aid the eco-friendliness of a building by blocking solar radiation when necessary. Merck’s initial measurements have shown potential energy savings of up to 40%. One main advantage of this iteration of the technology over competitor’s efforts is the high colour neutrality being touted.

This investment from Merck is one of the major steps in the company’s attempt to expand its influence in the LC market beyond displays, as part of the companies LC 2021 initiative. The windows can already be seen in action in Merck’s Innovation Center in Darmstadt, Germany.

LC driving glasses

A new technology to make driving at night a more comfortable experience has been proposed by start-up company, Inoptec, and Cambridgeshire-based PA Consulting [7,8]. The concept is based around glasses featuring LC technology which can react to block glare from oncoming traffic. The glasses demonstrate the ability to balance a variety of light intensity levels at a faster rate than the human eye is capable of. The device can also be synchronised with the headlights or other light sources of the user, allowing foreign sources of glare to be removed while maintaining the same lighting conditions for the user.

After conception by Inoptec, the technology was rapidly prototyped by PA Consulting, and demonstrated at the New Scientist Live event in London in September.

Disclosure statement

No potential conflict of interest was reported by the author.