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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 and γ for the optical cells with 5CB LCs (OTS–OTS interfaces).Notes: (A) Parameter S ≡ max (S−) − min (S−) =2αIout sin γ; (B) optical phase retardation .Abbreviations: LCs, liquid crystals; 5CB, 4-cyano-4′-pentylbiphenyl; OTS, octyltrichlorisilane.
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f3-ijn-10-025: Measured parameters S and γ for the optical cells with 5CB LCs (OTS–OTS interfaces).Notes: (A) Parameter S ≡ max (S−) − min (S−) =2αIout sin γ; (B) optical phase retardation .Abbreviations: LCs, liquid crystals; 5CB, 4-cyano-4′-pentylbiphenyl; OTS, octyltrichlorisilane.

Mentions: In this work, we use the top substrate of an optical cell as a reference interface, which is supposed to produce least birefringence in this system. Various surfaces such as OTS-functionalized glass surface and glass substrate where Au is deposited at 45°, can be used as a reference interface that can be reproducible. The OTS-functionalized surface supports homeotropic orientation of LCs and is expected to produce the smaller optical birefringence than the other. We experimentally check the birefringence properties of the two kinds of interfaces by measuring S and γ. Figure 3A and B show the S and γ for optical cells with the OTS–OTS interfaces, while Figure 4A and B for optical cells with the Au45–Au45 interfaces. The Au45 interface is treated with octanethiol to make planar orientation of LCs. The injection of LCs (1 or 2 μL) into the optical cell causes the S to increase despite the fact that the transmitted intensity of light through the cells remains nearly unchanged for both cases (OTS–OTS interfaces and Au45–Au45 interfaces). This is due to the fact that the γ increases with the LCs injection compared to that of the empty cell, which reflects the inherent background birefringence. Note that, in the case of OTS–OTS interfaces, the γ increases by less than 5% with the LCs injection, revealing that the OTS–OTS interfaces allow the negligible response of the optical cell to the LCs injection or to its concentration change.


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 and γ for the optical cells with 5CB LCs (OTS–OTS interfaces).Notes: (A) Parameter S ≡ max (S−) − min (S−) =2αIout sin γ; (B) optical phase retardation .Abbreviations: LCs, liquid crystals; 5CB, 4-cyano-4′-pentylbiphenyl; OTS, octyltrichlorisilane.
© Copyright Policy
Related In: Results  -  Collection

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

f3-ijn-10-025: Measured parameters S and γ for the optical cells with 5CB LCs (OTS–OTS interfaces).Notes: (A) Parameter S ≡ max (S−) − min (S−) =2αIout sin γ; (B) optical phase retardation .Abbreviations: LCs, liquid crystals; 5CB, 4-cyano-4′-pentylbiphenyl; OTS, octyltrichlorisilane.
Mentions: In this work, we use the top substrate of an optical cell as a reference interface, which is supposed to produce least birefringence in this system. Various surfaces such as OTS-functionalized glass surface and glass substrate where Au is deposited at 45°, can be used as a reference interface that can be reproducible. The OTS-functionalized surface supports homeotropic orientation of LCs and is expected to produce the smaller optical birefringence than the other. We experimentally check the birefringence properties of the two kinds of interfaces by measuring S and γ. Figure 3A and B show the S and γ for optical cells with the OTS–OTS interfaces, while Figure 4A and B for optical cells with the Au45–Au45 interfaces. The Au45 interface is treated with octanethiol to make planar orientation of LCs. The injection of LCs (1 or 2 μL) into the optical cell causes the S to increase despite the fact that the transmitted intensity of light through the cells remains nearly unchanged for both cases (OTS–OTS interfaces and Au45–Au45 interfaces). This is due to the fact that the γ increases with the LCs injection compared to that of the empty cell, which reflects the inherent background birefringence. Note that, in the case of OTS–OTS interfaces, the γ increases by less than 5% with the LCs injection, revealing that the OTS–OTS interfaces allow the negligible response of the optical cell to the LCs injection or to its concentration change.

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