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Optical birefringence of liquid crystals for label-free optical biosensing diagnosis.

Nguyen TT, Han GR, Jang CH, Ju H - Int J Nanomedicine (2015)

Bottom Line: We also provide estimation of the zenithal orientation of LCs near the gold surface of the hybrid interfaces, based on the phase retardation determined.The estimated limit of bovine serum albumin detection is approximately 2.1 μM.This optical technique with LCs can serve an optical platform for label-free quantitative diagnosis of proteins in a real time manner.

View Article: PubMed Central - PubMed

Affiliation: Department of Bionano Technology, Gachon University, Seongnam-City, South Korea.

ABSTRACT

Purpose: We present a polarization-sensitive optical detection platform for label-free quantitative optical biosensing diagnosis using liquid crystals (LCs). This is capable of determining quantitatively the optical birefringence of optical cells containing LCs, whose orientation depends on the immobilized biomolecules.

Patients and methods: This technique uses a polarization-dependent double-port detection without any polarizer at a single wavelength and removes the need of aligning optical cells of LCs in the azimuthal direction, with respect to the light path through the optical cell. Thus, this technique enables a stand-alone detection in a relatively compact format without an additional optical instrument, such as a retardation compensator, a Michael-Levy chart, and a spectrophotometer, in order to determine the optical birefringence quantitatively.

Results: We demonstrate that bovine serum albumin immobilized on the gold surface of the cell hybrid interfaces that support both homeotropic and planar anchoring of LCs causes optical phase retardation change which can be determined quantitatively. We also provide estimation of the zenithal orientation of LCs near the gold surface of the hybrid interfaces, based on the phase retardation determined. The estimated limit of bovine serum albumin detection is approximately 2.1 μM.

Conclusion: This optical technique with LCs can serve an optical platform for label-free quantitative diagnosis of proteins in a real time manner.

No MeSH data available.


Related in: MedlinePlus

Measured parameters S, γ, and the corresponding zenithal angle θ for the optical cells with 5CB LCs subject to the OTS–Au0 or the OTS–Au45 interfaces for the BSA sensing.Notes: (A) Parameter S ≡ max (S−) − min (S−) =2αIout sin γ; (B) optical phase retardation  with the estimated zenithal angle θ of 5CB LCs; (C) optical images of 5CB supported on OTS–Au0 with no BSA; (D) OTS–Au45 with No BSA; and (E) OTS–Au45 with BSA.Abbreviations: LCs, liquid crystals; 5CB, 4-cyano-4′-pentylbiphenyl; OTS, octyltrichlorisilane; Au0, gold-coated surface at a deposition angle of 0°; Au45, gold-coated surface at a deposition angle of 45°; BSA, bovine serum albumin.
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f6-ijn-10-025: Measured parameters S, γ, and the corresponding zenithal angle θ for the optical cells with 5CB LCs subject to the OTS–Au0 or the OTS–Au45 interfaces for the BSA sensing.Notes: (A) Parameter S ≡ max (S−) − min (S−) =2αIout sin γ; (B) optical phase retardation with the estimated zenithal angle θ of 5CB LCs; (C) optical images of 5CB supported on OTS–Au0 with no BSA; (D) OTS–Au45 with No BSA; and (E) OTS–Au45 with BSA.Abbreviations: LCs, liquid crystals; 5CB, 4-cyano-4′-pentylbiphenyl; OTS, octyltrichlorisilane; Au0, gold-coated surface at a deposition angle of 0°; Au45, gold-coated surface at a deposition angle of 45°; BSA, bovine serum albumin.

Mentions: In order to see the effects of the Au deposition angle of the interface, we compare the two kinds of hybrid interfaces, ie, the hybrid interfaces described above (OTS–Au45 interfaces), and those consisting of the OTS-functionalized interface (reference) and the Au interface deposited at the angle of 0° (OTS–Au0 interfaces). As illustrated in Figure 6A and B, the OTS–Au0 interfaces with 1 μL LCs produce the S and the γ, both of which are substantially smaller than those of the OTS–Au45 interfaces, respectively, for the same amount of LCs injected in between. The OTS–Au0 hybrid interfaces provide a γ even smaller than that of the OTS–OTS interfaces. The fact that target biomolecules immobilized to LCs on the Au surface are likely to disrupt their orientations in a random fashion and consequently decrease γ leads us to use OTS–Au45 hybrid interface for sensing analyte molecules. This is due to the fact that planar anchoring of LCs on the Au surface (45° deposition) produces birefringence much larger than the case with Au surface of 0° deposition.


Optical birefringence of liquid crystals for label-free optical biosensing diagnosis.

Nguyen TT, Han GR, Jang CH, Ju H - Int J Nanomedicine (2015)

Measured parameters S, γ, and the corresponding zenithal angle θ for the optical cells with 5CB LCs subject to the OTS–Au0 or the OTS–Au45 interfaces for the BSA sensing.Notes: (A) Parameter S ≡ max (S−) − min (S−) =2αIout sin γ; (B) optical phase retardation  with the estimated zenithal angle θ of 5CB LCs; (C) optical images of 5CB supported on OTS–Au0 with no BSA; (D) OTS–Au45 with No BSA; and (E) OTS–Au45 with BSA.Abbreviations: LCs, liquid crystals; 5CB, 4-cyano-4′-pentylbiphenyl; OTS, octyltrichlorisilane; Au0, gold-coated surface at a deposition angle of 0°; Au45, gold-coated surface at a deposition angle of 45°; BSA, bovine serum albumin.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4554411&req=5

f6-ijn-10-025: Measured parameters S, γ, and the corresponding zenithal angle θ for the optical cells with 5CB LCs subject to the OTS–Au0 or the OTS–Au45 interfaces for the BSA sensing.Notes: (A) Parameter S ≡ max (S−) − min (S−) =2αIout sin γ; (B) optical phase retardation with the estimated zenithal angle θ of 5CB LCs; (C) optical images of 5CB supported on OTS–Au0 with no BSA; (D) OTS–Au45 with No BSA; and (E) OTS–Au45 with BSA.Abbreviations: LCs, liquid crystals; 5CB, 4-cyano-4′-pentylbiphenyl; OTS, octyltrichlorisilane; Au0, gold-coated surface at a deposition angle of 0°; Au45, gold-coated surface at a deposition angle of 45°; BSA, bovine serum albumin.
Mentions: In order to see the effects of the Au deposition angle of the interface, we compare the two kinds of hybrid interfaces, ie, the hybrid interfaces described above (OTS–Au45 interfaces), and those consisting of the OTS-functionalized interface (reference) and the Au interface deposited at the angle of 0° (OTS–Au0 interfaces). As illustrated in Figure 6A and B, the OTS–Au0 interfaces with 1 μL LCs produce the S and the γ, both of which are substantially smaller than those of the OTS–Au45 interfaces, respectively, for the same amount of LCs injected in between. The OTS–Au0 hybrid interfaces provide a γ even smaller than that of the OTS–OTS interfaces. The fact that target biomolecules immobilized to LCs on the Au surface are likely to disrupt their orientations in a random fashion and consequently decrease γ leads us to use OTS–Au45 hybrid interface for sensing analyte molecules. This is due to the fact that planar anchoring of LCs on the Au surface (45° deposition) produces birefringence much larger than the case with Au surface of 0° deposition.

Bottom Line: We also provide estimation of the zenithal orientation of LCs near the gold surface of the hybrid interfaces, based on the phase retardation determined.The estimated limit of bovine serum albumin detection is approximately 2.1 μM.This optical technique with LCs can serve an optical platform for label-free quantitative diagnosis of proteins in a real time manner.

View Article: PubMed Central - PubMed

Affiliation: Department of Bionano Technology, Gachon University, Seongnam-City, South Korea.

ABSTRACT

Purpose: We present a polarization-sensitive optical detection platform for label-free quantitative optical biosensing diagnosis using liquid crystals (LCs). This is capable of determining quantitatively the optical birefringence of optical cells containing LCs, whose orientation depends on the immobilized biomolecules.

Patients and methods: This technique uses a polarization-dependent double-port detection without any polarizer at a single wavelength and removes the need of aligning optical cells of LCs in the azimuthal direction, with respect to the light path through the optical cell. Thus, this technique enables a stand-alone detection in a relatively compact format without an additional optical instrument, such as a retardation compensator, a Michael-Levy chart, and a spectrophotometer, in order to determine the optical birefringence quantitatively.

Results: We demonstrate that bovine serum albumin immobilized on the gold surface of the cell hybrid interfaces that support both homeotropic and planar anchoring of LCs causes optical phase retardation change which can be determined quantitatively. We also provide estimation of the zenithal orientation of LCs near the gold surface of the hybrid interfaces, based on the phase retardation determined. The estimated limit of bovine serum albumin detection is approximately 2.1 μM.

Conclusion: This optical technique with LCs can serve an optical platform for label-free quantitative diagnosis of proteins in a real time manner.

No MeSH data available.


Related in: MedlinePlus