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An Electrochemical Cholesteric Liquid Crystalline Device for Quick and Low-Voltage Color Modulation
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Cholesteric Liquid Crystal Droplets for Biosensors
Hyun-Gyu Lee1, Sundas Munir1, Soo-Young Park1
1Department of Polymer Science & Engineering, Polymeric Nanomaterials Laboratory, School of Applied Chemical Engineering, Kyungpook National University , 80 Daehak-ro, Buk-gu, Daegu 41566, Korea.
ACS Applied Materials & Interfaces
|September 13, 2016
Summary
We developed cholesteric liquid crystal (CLC) droplets using microfluidics for sensitive biosensing. These droplets change color patterns to detect glucose and cholesterol without needing polarizers.
Area of Science:
- Materials Science
- Nanotechnology
- Biochemistry
Background:
- Cholesteric liquid crystals (CLCs) exhibit unique optical properties based on their helical structure.
- Controlling the helical structure and surface anchoring of CLCs is crucial for their application in sensors.
- Microfluidics offers a precise method for fabricating uniform CLC droplets.
Purpose of the Study:
- To prepare uniformly sized CLC droplets using microfluidics.
- To investigate the influence of surface modification on CLC droplet structure and optical properties.
- To develop CLC-based biosensors for glucose and cholesterol detection.
Main Methods:
- Microfluidic preparation of cholesteric liquid crystal (CLC) droplets doped with a chiral dopant.
- Surface modification of CLC droplets using poly(vinyl alcohol) (PVA), sodium dodecyl sulfate (SDS), and pH-responsive polymers (PAA-b-LCP).
- Immobilization of enzymes (glucose oxidase and cholesterol oxidase) within CLC droplets for biosensing applications.
Main Results:
- Surface modification with SDS induced a transition from planar to homeotropic anchoring, altering the droplet's color pattern from a central spot to a chicken-skin and then flashlight pattern.
- pH-responsive CLC droplets (CLCPAA) exhibited reversible changes in helical structure and color patterns due to protonation/deprotonation of the PAA coating.
- Immobilized CLCPAA-GOx and CLCPAA-ChO droplets demonstrated high sensitivity (0.5 μM and 2.5 μM, respectively), selectivity, and rapid response (≤4 s) for glucose and cholesterol detection.
- The color patterns of CLC droplets allowed for detection without the need for crossed polarizers.
Conclusions:
- Microfluidically prepared CLC droplets can be functionalized for tunable optical responses.
- Surface anchoring control is key to manipulating CLC droplet morphology and optical properties.
- The developed CLC-based biosensors offer a promising, polarizer-free platform for sensitive and selective detection of analytes like glucose and cholesterol.
