Self-Assembly of Bioconjugated Amphiphilic Mesogens Having Specific Binding Moieties at Aqueous-Liquid Crystal Interfaces

New bioconjugated amphiphilic mesogens with recognition groups have been synthesized, and their self assembly behavior has been characterized at aqueous liquid crystal (LC) interfaces. Specifically, the rod-shaped 2,3-difluoro-4'-(4-trans-pentylcyclohexyl)biphenyl-based mesogen was conjugated with either biotin or the arginine glycine aspartic acid (RGD) peptide sequence through a tetraethylene glycol chain. Langmuir film measurements revealed that the two biorecognition moieties lead to very different surface pressure area isotherms, indicating that biotin and RGD have distinct effects on self-assembled monolayers formed by these bioconjugated mesogens at aqueous surfaces. Measurements of the surface-induced orientations of LCs exhibited by biotin-conjugated mesogens mixed with the room-temperature nematic LC 4-cyano-4'-pentylbiphenyl (5CB) revealed formation of cholesteric phases (consistent with the chiral nature of biotin) and evidence of the presence of the conjugated mesogen at aqueous interfaces. Preliminary measurements based on fluorescence measurements using Texas Red-labeled streptavidin confirmed that the biotin mesogen is located at the interface and capable of specific recognition of streptavidin. Overall, these results demonstrate that bioconjugated mesogens provide the basis of a general and facile method for the introduction of biological recognition functionality at aqueous LC interface. These LC interfaces have mobility, elastic properties and responsiveness that are distinct from past studies of biorecognition groups presented at the interface of a solid or isotropic liquid, and the results thus provide a new approach for the introduction of biorecognition groups into this important and promising class of interface for biological and analytical applications.