Ellipsometric Approach for the Real-Time Detection of Label-Free Protein Adsorption by Second Harmonic Generation

Polizzi, Mark A.; Plocinik, Ryan M.; Simpson, Garth J.

doi:10.1021/ja031627v

Cited by 40 publications

(43 citation statements)

References 49 publications

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“…72 SHG-CD was shown to be a particularly sensitive probe of the redox state of the heme group, which is known to be essential for the electron transfer process that occurs in cytochrome c. Simpson and co-workers used chiral SHG experiments to observe the dynamics of protein binding (bovine serum albumin) to a surface. 73 Their experimental results are shown in Figure 7. Recently, chiral SHG signals from the peptide melittin allowed Conboy et al to detect its binding to a lipid bilayer.…”

Section: Surface Nonlinear Opticsmentioning

confidence: 99%

Nonlinear optical spectroscopy of chiral molecules

2005

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We review nonlinear optical processes that are specific to chiral molecules in solution and on surfaces. In contrast to conventional natural optical activity phenomena, which depend linearly on the electric field strength of the optical field, we discuss how optical processes that are nonlinear (quadratic, cubic, and quartic) functions of the electromagnetic field strength may probe optically active centers and chiral vibrations. We show that nonlinear techniques open entirely new ways of exploring chirality in chemical and biological systems: The cubic processes give rise to nonlinear circular dichroism and nonlinear optical rotation and make it possible to observe dynamic chiral processes at ultrafast time scales. The quadratic second-harmonic and sum-frequency-generation phenomena and the quartic processes may arise entirely in the electric-dipole approximation and do not require the use of circularly polarized light to detect chirality. They provide surface selectivity and their observables can be relatively much larger than in linear optical activity. These processes also give rise to the generation of light at a new color, and in liquids this frequency conversion only occurs if the solution is optically active. We survey recent chiral nonlinear optical experiments and give examples of their application to problems of biophysical interest.

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Section: Surface Nonlinear Opticsmentioning

confidence: 99%

Nonlinear optical spectroscopy of chiral molecules

2005

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“…[97] In other studies, Polizzi et al have developed an ellipsometric approach for selectively probing the orientational changes induced within a weakly bound SHG-active local probe molecule upon coadsorption of a protein. [33] In general, any perturbation that significantly changes the nonlinear optical properties of an interface can be selectively isolated simply by placing an appropriately oriented combination of a quarter-wave plate and half-wave plate in the path of the detected nonlinear optical beam. [33] In one specific example of this general approach, bovine serum albumin (BSA) binding at the glass/aqueous solution interface was measured in real time and with chiral specificity by the structural chirality induced in an achiral rhodamine dye coadsorbate ( Figure 5) upon protein binding.…”

Section: Chirality In Nonlinear Optical Biosensing Applicationsmentioning

confidence: 99%

“…[1,4,5, The chiral specificity of these methods also opens up new opportunities for the development of chiral-selective surface detection and analysis approaches. [32,33] Emerging second-harmonic and sum-frequency microscopy methods for imaging biological samples demand an understanding of the role of chirality to assist in interpreting the nonlinear optical image contrast. [34][35][36][37][38][39][40][41] Additionally, the novel symmetry properties of SHG and SFG in chiral media suggest that new nonlinear optical materials can be constructed that exploit these chiroptical effects.…”

Section: Introductionmentioning

confidence: 99%

Molecular Origins of the Remarkable Chiral Sensitivity of Second‐Order Nonlinear Optics

2004

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Recent observations of remarkably large chiroptical effects in second-harmonic generation (SHG) and sum-frequency generation (SFG) measurements suggest exciting possibilities for the development of new chiral-specific spectroscopies and novel chiral materials for nonlinear optics. Several fundamental studies designed to elucidate the molecular and macromolecular origins of the chiral responses are reviewed to provide a framework for development of this emerging field. In general, the chiral activity in SHG and SFG has the potential to arise from complex interactions between hosts of different competing effects. Fortunately, relatively simple electric dipole-allowed mechanisms routinely dominate the nonlinear optical chiral activities of most practical systemsexpressions can often be generated to link the. This substantial reduction in complexity allows for the development of simple models connecting the macroscopic nonlinear optical response to intuitive molecular and supramolecular properties.

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“…Electronic resonance enhancement is used to detect chiral SFG vibrational spectra generated from the molecular chirality, because under electronic resonance the asymmetric Raman tensor components will be greatly enhanced by the electronicvibrational coupling (18). Strong SHG and SFG signals can be observed from chiral molecules; however, Simpson and coworkers (33)(34)(35)(36)(37) demonstrated by using SHG that achiral molecules adsorbed on a surface or interface may generate detectable nonlinear optical chiral signals. They concluded that macromolecular orientational effects can dominate the chiroptical responses of uniaxial systems.…”

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confidence: 99%

Detection of chiral sum frequency generation vibrational spectra of proteins and peptides at interfaces in situ

Wang

Chen

Clarke

et al. 2005

Proc. Natl. Acad. Sci. U.S.A.

190

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In this work, we demonstrate the feasibility to collect off-electronic resonance chiral sum frequency generation (SFG) vibrational spectra from interfacial proteins and peptides at the solid͞liquid interface in situ. It is difficult to directly detect a chiral SFG vibrational spectrum from interfacial fibrinogen molecules. By adopting an interference enhancement method, such a chiral SFG vibrational spectrum can be deduced from interference spectra between the normal achiral spectrum and the chiral spectrum. We found that the chiral SFG vibrational spectrum of interfacial fibrinogen was mainly contributed by the ␤-sheet structure. For a ␤-sheet peptide tachyplesin I, which may be quite ordered at the solid͞liquid interface, chiral SFG vibrational spectra can be collected directly. We believe that these chiral signals are mainly contributed by electric dipole contributions, which can dominate the chiroptical responses of uniaxial systems. For the first time, to our knowledge, this work indicates that the off-electronic resonance SFG technique is sensitive enough to collect chiral SFG vibrational spectra of interfacial proteins and peptides, providing more structural information to elucidate interfacial protein and peptide structures. chiral vibrational spectroscopy ͉ interfacial proteins and peptides U nderstanding chirality is important in biology, chemistry, and medicine. For example, chiral surfaces and interfaces are important in asymmetric chemical synthesis, chiral molecule separation, binding between chiral drugs and proteins, crystal growth, and the adsorption of proteins on biomedical material surfaces. Since the excellent work on chiroptical effects using second-harmonic generation (SHG) was presented by Hicks and coworkers (1-4) and Persoons and coworkers (5-7), extensive research has been performed to investigate such effects in oriented thin films or bulk media by using SHG and sum frequency generation (SFG) spectroscopic techniques (8-38). Many excellent experimental demonstrations and theoretical treatments on this topic have been published in the last decade or so. These studies indicate that more structural information about chiral materials can possibly be deduced by SHG and SFG studies. It has been demonstrated that the nonlinear chiral effect detected by nonlinear optical methods, such as SHG and SFG, can be several orders of magnitude larger than those detected by linear optical methods (refs. 8, 29, and 36 and references therein).Currently, several general models have been used to interpret the molecular mechanisms of second-order nonlinear chiral spectra (ref. 36 and references therein). Some experimental results can be interpreted by magnetic-dipole contributions and͞or interference between electric and magnetic-dipole contributions. For other experiments, the factors mentioned above cannot explain the very strong nonlinear chiral signal observed, and interpretations based on a pure electric-dipole contribution have been proposed. Recently, Shen and coworkers (10,17) demonstrated that chir...

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Ellipsometric Approach for the Real-Time Detection of Label-Free Protein Adsorption by Second Harmonic Generation

Cited by 40 publications

References 49 publications

Nonlinear optical spectroscopy of chiral molecules

Nonlinear optical spectroscopy of chiral molecules

Molecular Origins of the Remarkable Chiral Sensitivity of Second‐Order Nonlinear Optics

Detection of chiral sum frequency generation vibrational spectra of proteins and peptides at interfaces in situ

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