Improving Liquid-Crystal-Based Biosensing in Aqueous Phases

Abstract

Liquid crystal (LC)-based biological sensors permit the study of aqueous biological samples without the need for the labeling of biological species with fluorescent dyes (which can be laborious and change the properties of the biological sample under study). To date, studies of LC-based biosensors have explored only a narrow range of the liquid crystal/alignment layer combinations essential to their operation. Here we report a study of the role of LC elastic constants and the surface anchoring energy in determining the sensitivity of LC-based biosensors. By investigating a mixture of rod-shape and bent-shape mesogens, and three different alignment layers, we were able to widen the useful detection range of a LC-based sensor by providing an almost linear mapping of effective birefringence with concentration between 0.05 and 1mM of an anionic surfactant (model target analyte). These studies pave the way for optimization of LC-based biosensors and reveal the importance of the choice of both the LC material and the alignment layer in determining sensor properties.

Thermotropic Liquid Crystal-Assisted Chemical and Biological Sensors

“…Iglesias et al [ 6 ] studied the effect of adjusting the elastic constants of the LC films by adding bent-core LC to 5CB. They found that the range of sensitivity to a simple surfactant, SDS, increased and a nearly linear response signal was achieved as shown in Figure 11 .…”

“…The unique combination of LC responsiveness to the environment and the striking optical effects that allow the rapid visualization of this response facilitates the use of LCs in sensing applications. The LC responds to several different classes of molecules, including surface-active agents such as lipids and surfactants [ 5 , 6 , 7 , 8 , 9 ] and non-surface-active molecules such as gas vapors [ 10 , 11 , 12 , 13 ] and can be tailored to respond only to specific antigens [ 9 , 10 , 14 , 15 , 16 , 17 ].…”

Morphology Tuning of Electrospun Liquid Crystal/Polymer Fibers

“…This is because if liquid crystals are incorporated into the fibers, they maintain all their responsive properties including their optical responset oc hanges in temperature [16] or application of an electric field [17] and their ability to sense the presence of chemical [18,19] or biological stimuli. [20,21] Methods for the fabrication of polymerf ibers, including electrospinning, [22,23] solution blow spinning, [24,25] and other methods, [26] are relativelyw ell-developeda nd understoodt echniques. Amongt hem,e lectrospinning has been widely adopted due to its versatility and flexibility.E ncapsulation of LC in an electrospun polymerf iber is am uch less-developed technique.…”

Low-voltage electro-optical memory device based on NiO nanorods dispersed in a ferroelectric liquid crystal

“…7 Among the members of the so matter family, liquid crystals (LCs) have attracted a great deal of scientic interest owing to their unique electro-optical properties for displays as well as non-display applications such as lenses, spatial light modulators, antennas, sensors etc. [8][9][10][11] Also, the so memory behavior shown by LCs are fascinating one due to its use as an active component for futuristic and motivating memory devices. The non-volatile memory seen in different LC systems are the topological frustrations driven memory effect in nematic LC, 12,13 sub microsecond bistable electro-optic switching in surface stabilized ferroelectric liquid crystal (FLC), 14 electro-mechanical helix deformations in deformed helix FLCs, 15 nano structured materials induced electro-optical memory effect in LCs 16 etc.…”