Optical amplification of ligand-receptor binding using liquid crystals

Science

Volumn 279, Issue 5359, 1998, Pages 2077-2080

  Gupta, Vinay K ^a,b   Skaife, Justin J ^a   Dubrovsky, Timothy B ^a,c   Abbott, Nicholas L ^a  

^a University of California   (United States)

^b UNIVERSITY OF ILLINOIS AT URBANA CHAMPAIGN   (United States)

^c HOFFMANN LA ROCHE INC   (United States)

Author keywords

[No Author keywords available]

Indexed keywords

LIGAND; RECEPTOR;

ARTICLE; CONFORMATIONAL TRANSITION; LIGAND BINDING; LIGHT; LIQUID CRYSTAL; PRIORITY JOURNAL;

ANISOTROPY; ANTIGEN-ANTIBODY REACTIONS; AVIDIN; BIOTIN; BIOTINYLATION; CRYSTALLIZATION; GOLD; IMMUNOGLOBULIN G; LIGANDS; OPTICS; PROTEIN BINDING;

EID: 0032571404     PISSN: 00368075     EISSN: None     Source Type: Journal    
DOI: 10.1126/science.279.5359.2077     Document Type: Article

References (32)

1. N. B. Gamaleya, Forensic Sci. Int. 63, 285 (1993); A. Solans, M. Carnicero, R. Delatorre, J. Segura, J. Anal. Toxicol. 19, 104 (1995).
2. N. B. Gamaleya, Forensic Sci. Int. 63, 285 (1993); A. Solans, M. Carnicero, R. Delatorre, J. Segura, J. Anal. Toxicol. 19, 104 (1995).
3. H. M. Crews and A. B. Hanley, Biomarkers in Food Chemical Risk Assessment (Royal Society of Chemistry, Cambridge, 1995).
4. C. P. Price and D. J. Newman, Principles and Practice of Immunoassays (Macmillan, New York, 1991); D. Wild, The Immunoassay Handbook (Macmillan, New York, 1994).
5. C. P. Price and D. J. Newman, Principles and Practice of Immunoassays (Macmillan, New York, 1991); D. Wild, The Immunoassay Handbook (Macmillan, New York, 1994).
6. Several recent studies have detected the binding of proteins and ligands at surfaces by means of electroanalytical methods in combination with sliding ion channels [B. A. Cornell et al., Nature 387, 580 (1997)] or interferometric methods based on porous silicon [V. S.-Y. Lin et al., Science 278, 840 (1997)]. Stress-induced chromatic transitions caused by multivalent attachment of proteins and viruses to liposomes in solution or to polymer films prepared at the surface of water and transferred to a solid substrate have also been reported [D. H. Charych, J. O. Nagy, W. Spevak, M. D. Bednarski, Science 261, 585 (1993); D. Charych et al., Chem. Biol. 3, 113 (1996); J. Pan and D. Charych, Langmuir 13, 1365 (1997)]. Our approach, in contrast, is not restricted to multivalent binding events, does not require the use of complex instrumentation, and uses surfaces that can be formed spontaneously from solution and readily patterned.
7. Several recent studies have detected the binding of proteins and ligands at surfaces by means of electroanalytical methods in combination with sliding ion channels [B. A. Cornell et al., Nature 387, 580 (1997)] or interferometric methods based on porous silicon [V. S.-Y. Lin et al., Science 278, 840 (1997)]. Stress-induced chromatic transitions caused by multivalent attachment of proteins and viruses to liposomes in solution or to polymer films prepared at the surface of water and transferred to a solid substrate have also been reported [D. H. Charych, J. O. Nagy, W. Spevak, M. D. Bednarski, Science 261, 585 (1993); D. Charych et al., Chem. Biol. 3, 113 (1996); J. Pan and D. Charych, Langmuir 13, 1365 (1997)]. Our approach, in contrast, is not restricted to multivalent binding events, does not require the use of complex instrumentation, and uses surfaces that can be formed spontaneously from solution and readily patterned.
8. Several recent studies have detected the binding of proteins and ligands at surfaces by means of electroanalytical methods in combination with sliding ion channels [B. A. Cornell et al., Nature 387, 580 (1997)] or interferometric methods based on porous silicon [V. S.-Y. Lin et al., Science 278, 840 (1997)]. Stress-induced chromatic transitions caused by multivalent attachment of proteins and viruses to liposomes in solution or to polymer films prepared at the surface of water and transferred to a solid substrate have also been reported [D. H. Charych, J. O. Nagy, W. Spevak, M. D. Bednarski, Science 261, 585 (1993); D. Charych et al., Chem. Biol. 3, 113 (1996); J. Pan and D. Charych, Langmuir 13, 1365 (1997)]. Our approach, in contrast, is not restricted to multivalent binding events, does not require the use of complex instrumentation, and uses surfaces that can be formed spontaneously from solution and readily patterned.
9. Several recent studies have detected the binding of proteins and ligands at surfaces by means of electroanalytical methods in combination with sliding ion channels [B. A. Cornell et al., Nature 387, 580 (1997)] or interferometric methods based on porous silicon [V. S.-Y. Lin et al., Science 278, 840 (1997)]. Stress-induced chromatic transitions caused by multivalent attachment of proteins and viruses to liposomes in solution or to polymer films prepared at the surface of water and transferred to a solid substrate have also been reported [D. H. Charych, J. O. Nagy, W. Spevak, M. D. Bednarski, Science 261, 585 (1993); D. Charych et al., Chem. Biol. 3, 113 (1996); J. Pan and D. Charych, Langmuir 13, 1365 (1997)]. Our approach, in contrast, is not restricted to multivalent binding events, does not require the use of complex instrumentation, and uses surfaces that can be formed spontaneously from solution and readily patterned.
10. Several recent studies have detected the binding of proteins and ligands at surfaces by means of electroanalytical methods in combination with sliding ion channels [B. A. Cornell et al., Nature 387, 580 (1997)] or interferometric methods based on porous silicon [V. S.-Y. Lin et al., Science 278, 840 (1997)]. Stress-induced chromatic transitions caused by multivalent attachment of proteins and viruses to liposomes in solution or to polymer films prepared at the surface of water and transferred to a solid substrate have also been reported [D. H. Charych, J. O. Nagy, W. Spevak, M. D. Bednarski, Science 261, 585 (1993); D. Charych et al., Chem. Biol. 3, 113 (1996); J. Pan and D. Charych, Langmuir 13, 1365 (1997)]. Our approach, in contrast, is not restricted to multivalent binding events, does not require the use of complex instrumentation, and uses surfaces that can be formed spontaneously from solution and readily patterned.
11. S. Chandrasekhar, Liquid Crystals (Cambridge Univ. Press, New York, ed. 2, 1992); P.-G. de Gennes and J. Prost, The Physics of Liquid Crystals (Oxford Univ. Press, New York, ed. 2, 1993).
12. S. Chandrasekhar, Liquid Crystals (Cambridge Univ. Press, New York, ed. 2, 1992); P.-G. de Gennes and J. Prost, The Physics of Liquid Crystals (Oxford Univ. Press, New York, ed. 2, 1993).
13. Indirect amplification of surface-bound analytes can be achieved with the use of enzyme-linked IgGs that bind to antigenic regions on analytes (3). In contrast to our approach, these methods require the use of IgGs labeled with enzymes and incubation of the surface-bound analytes with IgGs for tens of minutes, during which time the enzyme-linked IgGs bind to the analytes. A second incubation step, typically taking several minutes, is then required to enzymatically transform substrates into colored products.
14. We prepared gold films on a stationary glass substrate with a fixed angle of incidence of gold during deposition. Analysis of atomic force microscopy images of these films reveals their roughness to be greatest in a direction parallel to the direction of deposition of the gold. Using ellipsometry, we have also measured anisotropy in the amplitude and phase of reflected light (J. J. Skaife, V. K. Gupta, N. L. Abbott, unpublished data). On these gold films, nematic LCs orient uniformly in a direction perpendicular to the direction of incidence of the gold and parallel to the plane of the surface [V. K. Gupta and N. L. Abbott, Langmuir 12, 2587 (1996)]. A nematic LC has no preferred orientation in the plane of a gold film that is prepared by rotating the glass substrate during deposition of the gold.
15. We prepared gold films on a stationary glass substrate with a fixed angle of incidence of gold during deposition. Analysis of atomic force microscopy images of these films reveals their roughness to be greatest in a direction parallel to the direction of deposition of the gold. Using ellipsometry, we have also measured anisotropy in the amplitude and phase of reflected light (J. J. Skaife, V. K. Gupta, N. L. Abbott, unpublished data). On these gold films, nematic LCs orient uniformly in a direction perpendicular to the direction of incidence of the gold and parallel to the plane of the surface [V. K. Gupta and N. L. Abbott, Langmuir 12, 2587 (1996)]. A nematic LC has no preferred orientation in the plane of a gold film that is prepared by rotating the glass substrate during deposition of the gold.
16. J. Spinke et al., J. Chem. Phys. 99, 7012 (1993).
17. Mixed SAMs were also formed in a few minutes by using solutions that contained millimolar concentrations of the organothiols.
18. All thickness measurements were performed using a Rudolph Auto ellipsometer with light (633 nm) incident at an angle of 70°. A refractive index of 1.45 was used to estimate the thickness of bound layers of thiols and proteins. Standard deviations of the reported ellipsometric thicknesses (Δ) are ± 0.2 nm.
19. -15 M (3, 8) [P. C. Weber et al., Science 243, 85 (1989)].
20. Av = 0.2 to 0.6 nm. Nonspecific adsorption of proteins on SAMs can also be minimized by using alkanethiols end-functionalized with oligoethylene glycol or hydroxyl groups [K. L. Prime and G. M. Whitesides, J. Am. Chem. Soc. 115, 10714 (1993)].
21. When rotated between crossed polarizers, the light transmitted through the sample did not show a large modulation in intensity. This result indicates the absence of a preferred orientation of the LC within the cell. The general features of the optical textures were not influenced by variations in rates of cooling of the LC to the ambient temperature.
22. 6 mesogens per protein). We did not investigate LC films thicker than 20 μm because the optical effects of birefringence within a 20-μm-thick film of LC are easily seen with the naked eye. The threshold surface mass of avidin that causes reorientation of the LC is a strong function of the manner of deposition of the gold, the composition of the mixed SAM, and the type of LC (J. J. Skaife and N. L. Abbott, unpublished data).
23. d reported here correspond to values measured in bulk solution [see, for example, H. Bagci et al., FEBS Lett. 322, 47 (1993)].
24. Anti-Bi-IgG was purchased from Sigma BioScience and anti-FITC-IgG was purchased from Molecular Probes. All measurements were performed in PBS containing 0.5 μM IgG and 0.004% Triton X-100. After binding of the IgG in PBS, the samples were rinsed with deionized water and dried under a stream of nitrogen.
25. 11-Ala-Ala-Pro-Phe-p-nitroanilide.
26. Fluorescein-labeled streptavidin (FITC-Av) was purchased from Pierce. All measurements were performed in PBS containing 0.5 μM FITC-Av and 0.004% Triton X-100. After binding of the FITC-Av in PBS, the samples were rinsed with deionized water.
27. -10 M) to be 100 ppm (∼1 μM) when using liposomes in solution and 20 ppm (∼0.2 μM) when using supported films of the polymer (4). The use of this method to detect the binding of antibodies to antigens has not been reported.
28. The surfaces of a TNLC cell are designed such that the region of LC in contact with one surface is oriented at right angles to the region of LC in contact with the opposing surface (Fig. 2B). The LC sandwiched between the two surface regions of the cell undergoes a 90° twist-type deformation, and the polarization of linearly polarized light transmitted through such a cell is rotated by 90°. A twisted LC cell, when viewed between two parallel polarizers, appears dark. In contrast, a cell containing LC that is not twisted appears bright between parallel polars [B. Bahadur, Ed., Liquid Crystals: Applications and Uses (World Scientific, Singapore, 1990)].
29. A. Kumar et al., Acc. Chem. Res. 28, 219 (1995).
30. V. K. Gupta and N. L. Abbott, Science 276, 1533 (1997).
31. 8SH [V. K. Gupta and N. L. Abbott, Phys. Rev. E 54, 4540 (1996)].
32. Supported in part by NSF grants CTS-9502263 and DMR-9400354 and by the Office of Naval Research Presidential Early Career Award for Scientists and Engineers (N.L.A.). We thank Boehringer Mannheim and W. Knoll for their gift of BiSH, and G. Lopez and K. Oppermann for helpful suggestions.