Chemical and biological sensing using liquid crystals

Abstract

The liquid crystalline state of matter arises from orientation-dependent, non-covalent interaction between molecules within condensed phases. Because the balance of intermolecular forces that underlies formation of liquid crystals is delicate, this state of matter can, in general, be easily perturbed by external stimuli (such as an electric field in a display). In this review, we present an overview of recent efforts that have focused on exploiting the responsiveness of liquid crystals as the basis of chemical and biological sensors. In this application of liquid crystals, the challenge is to design liquid crystalline systems that undergo changes in organization when perturbed by targeted chemical and biological species of interest. The approaches described below revolve around the design of interfaces that selectively bind targeted species, thus leading to surface-driven changes in the organization of the liquid crystals. Because liquid crystals possess anisotropic optical and dielectric properties, a range of different methods can be used to read out the changes in organization of liquid crystals that are caused by targeted chemical and biological species. This review focuses on principles for liquid crystal-based sensors that provide an optical output.

Non-electronic gas sensors from electrospun mats of liquid crystal core fibres for detecting volatile organic compounds at room temperature

“…The response is due to the ability of certain gas molecules, even at low concentration, to strongly influence the liquid crystal self-assembly [40,[42][43][44][45], triggering a reorientation of the liquid crystal director [32,34,43,44], a change in period of the supramolecular helix of shortpitch cholesterics [19,36,42,[46][47][48], or even complete loss of long-range ordering [11]. In particular, Abbott and his group [35,39,[43][44][45] demonstrated the capability of nematic LCs as sensors for detecting nerve agents at concentrations as low as part per billion. Recently, the group also demonstrated highly sensitive detection of toluene vapour using nematics [32].…”

“…We are currently experiencing an increasing interest in gas sensors based on liquid crystals (LCs) [32][33][34][35][36][37][38][39][40][41], functioning at room temperature, requiring no energy supply as they are powered by thermal energy alone, and delivering a strong optical response that is easily detected without complex spectroscopic equipment. The response is due to the ability of certain gas molecules, even at low concentration, to strongly influence the liquid crystal self-assembly [40,[42][43][44][45], triggering a reorientation of the liquid crystal director [32,34,43,44], a change in period of the supramolecular helix of shortpitch cholesterics [19,36,42,[46][47][48], or even complete loss of long-range ordering [11].…”

Volumetric Properties of Sodium Decylsulfate Solutions at the Micelles Shape Transformations Region

“…Изучение таких систем при концентрациях, близких к их мицеллярной растворимости, является в настоящее время актуальным для биологии и медицины в связи с поисками новых антибиотиков на основе пептидов, модифици-рованных ионными ПАВ [7].…”

Thermodynamic Characteristics of the Surface of Spherical Micelles in Sodium n-Alkylsulphates Solution

“…В последние десятилетия эти исследования приобретают новое звучание в связи с успехами моделирования биологических объек-тов (липидов, протеинов, клеточных мембран и др. ), в том числе и с помощью мицеллярных и ве-зикулярных моделей [2]. В ряде публикаций [3][4][5][6][7][8] рассмотрены условия термодинамического и ме-ханического равновесия на искривленных поверх-ностях, а также применимости к нанообъектам уравнений, связывающих кривизну поверхности с поверхностным натяжением.…”