A label-free biosensor device based on registration of photonic crystal surface waves is described. Angular interrogation of the optical surface wave resonance is used to detect changes in the ...thickness of an adsorbed layer, while an additional simultaneous detection of the critical angle of total internal reflection provides independent data of the liquid refractive index. The abilities of the device are demonstrated by measuring of biotin molecule binding to a streptavidin monolayer, and by measuring association and dissociation kinetics of immunoglobulin G proteins. Additionally, deposition of PSS / PAH polyelectrolytes is recorded in situ resulting calculation of PSS and PAH monolayer thicknesses separately.
We present a new optical biosensor technique based on registration of dual optical s-polarized modes on a photonic crystal surface. The simultaneous registration of two optical surface waves with ...different evanescent depths from the same surface spot permits the segregation of the volume and the surface contributions from an analyte, while the absence of metal damping permits an increase in the propagation length of the optical surface waves and the sensitivity of the biosensor. Our technique was tested with the binding of biotin molecules to a streptavidin monolayer that has been detected with signal/noise ratio of ∼15 at 1-s signal accumulation time. The detection limit is ∼20 fg of the analyte on the probed spot of the surface.
•A new imaging biosensor technique based on photonic crystal surface modes (PCSMs) is presented.•The spectral shift of the PCSM resonance peak is detected by a standard color camera at each point of ...the PC chip surface.•The dynamic range of the biosensor in the adsorbate layer thickness is 150 nm and the baseline noise is 3.5 pm.•The first experiments using the device showed that the proposed imaging method can surpass its plasmonic analog (SPRi) with respect to both signal-to-noise ratio and dynamic range.
A novel biosensing technique with a two-dimensional (2D) visualization, which is based on photonic crystal surface modes (PC SMs), is presented. The 2D image of the surface with picometer thickness resolution can be obtained when the PC chip under study is placed between crossed polarizers to convert a PC SM resonance dip into a resonance peak. The PC chip is designed so that the PC SM resonance peak is located between the maxima of the blue and green pixels of a color camera. The spectral shift of the resonance peak is determined by balancing of the intensities of the blue and green pixels at each point in the color camera. The spatial distribution of resonance wavelength shifts across the camera reflects the spatial distribution of changes in the thickness of the adsorbate over the sample. The spatial resolution of the resulting 2D image is determined by the propagation length of the PC surface wave.
•A new imaging biosensor technique based on waveguide modes is presented.•A standard color camera detects spectral shifts at each point of the planar waveguide.•The baseline noise of the biosensor in ...the adsorbate layer thickness is 1.3 pm.•A comparison with the photonic crystal imaging biosensor is made.
A biosensing technique with a two-dimensional spatial resolution based on a planar optical waveguide is presented. The thickness of the waveguide is chosen such that the wavelength of the waveguide mode is located between the maxima of the blue and green pixels of a color camera. A prism based Kretschmann-like configuration is used for waveguide excitation. The prism is placed between crossed polarizers to obtain the waveguide resonance peak. The spectral shift of the resonance peak is determined through the normalized differences in intensities of the blue and green pixels at each point of the color camera. The spatial distribution of resonance wavelength shifts across the camera reflects the spatial distribution of changes in the thickness of the adsorbate over the sample. The sensitivity, dynamic range, and simplicity of practical implementation of this biosensor are compared with those of an imaging biosensor based on photonic crystal surface mode.
Efficient nonlinear conversion requires that interacting optical waves maintain a consistent phase relationship when traveling in a medium despite its dispersion. Birefringent phase-matching, which ...is often used to compensate for the dispersion, is not applicable to optically isotropic nonlinear materials. Here, we present a one-dimensional photonic crystal structure that allows the propagation of optical surface waves, both at the fundamental and third-harmonic frequencies, as an efficient medium for phase-matched third-harmonic generation. A unique advantage of this structure is that the effective refractive indices for the surface waves are similar to the refractive index of air at both frequencies. This allows phase-matching between the first and third harmonics, and a visible collinear beam of the third harmonic is produced at the prism-coupled output. Moreover, these optical surface waves propagate over long distances even if a lossy nonlinear nanofilm is deposited onto the photonic crystal surface. We provide experimental results for third-harmonic generation at a wavelength of 410 nm for a bare dielectric Ta
O
/SiO
multilayer structure and for the same structure coated with a 15-nm GaAs film.
We present experimental results on ultralong-range surface plasmon polaritons, propagating in a thin metal film on a one-dimensional (1D) photonic crystal surface over a distance of several ...millimeters. This propagation length is about 2 orders of magnitude higher than the one in the ordinary Kretschmann configuration at the same optical frequency. We show that a long-range surface plasmon polaritons propagation may take place not only in a (quasi)symmetrical scheme, where a thin metal film is located between two media with (approximately) the same refraction index, but also in a scheme where the thin metal film is located between an appropriate 1D photonic crystal and an arbitrary (air, water, etc.) medium. The ultralong-range surface plasmon polaritons are potentially important for biosensors, plasmonics, and other applications.
A high-precision optical biosensor technique capable of independently determining the refractive index (RI) of liquids is presented. Photonic crystal surface waves were used to detect surface binding ...events, while an independent registration of the critical angle was used for accurate determination of the liquid RI. This technique was tested using binding of biotin molecules to a streptavidin monolayer at low and high biotin concentrations. The attained baseline noise is
5
×
1
0
−
13
m/Hz
1/2 for adlayer thickness changes and
9
×
1
0
−
8
RIU/Hz
1/2 for RI changes.
Here, we propose and study several types of quartz surface coatings designed for the high-performance sorption of biomolecules and their subsequent detection by a photonic crystal surface mode (PC ...SM) biosensor. The deposition and sorption of biomolecules are revealed by analyzing changes in the propagation parameters of optical modes on the surface of a photonic crystal (PC). The method makes it possible to measure molecular and cellular affinity interactions in real time by independently recording the values of the angle of total internal reflection and the angle of excitation of the surface wave on the surface of the PC. A series of dextrans with various anchor groups (aldehyde, carboxy, epoxy) suitable for binding with bioligands have been studied. We have carried out comparative experiments with dextrans with other molecular weights. The results confirmed that dextran with a Mw of 500 kDa and anchor epoxy groups have a promising potential as a matrix for the detection of proteins in optical biosensors. The proposed approach would make it possible to enhance the sensitivity of the PC SM biosensor and also permit studying the binding process of low molecular weight molecules in real time.
We propose and demonstrate dendrimer-based coatings for a sensitive biochip surface that enhance the high-performance sorption of small molecules (i.e., biomolecules with low molecular weights) and ...the sensitivity of a label-free, real-time photonic crystal surface mode (PC SM) biosensor. Biomolecule sorption is detected by measuring changes in the parameters of optical modes on the surface of a photonic crystal (PC). We describe the step-by-step biochip fabrication process. Using oligonucleotides as small molecules and PC SM visualization in a microfluidic mode, we show that the PAMAM (poly-amidoamine)-modified chip's sorption efficiency is almost 14 times higher than that of the planar aminosilane layer and 5 times higher than the 3D epoxy-dextran matrix. The results obtained demonstrate a promising direction for further development of the dendrimer-based PC SM sensor method as an advanced label-free microfluidic tool for detecting biomolecule interactions. Current label-free methods for small biomolecule detection, such as surface plasmon resonance (SPR), have a detection limit down to pM. In this work, we achieved for a PC SM biosensor a Limit of Quantitation of up to 70 fM, which is comparable with the best label-using methods without their inherent disadvantages, such as changes in molecular activity caused by labeling.
Highlights
Long-range surface plasmons were first excited in a hybrid photonic-crystal/organic-light-emitting-diode microstructure containing two metal nanolayers.
These surface plasmons were excited ...without any external laser light, but by injecting current through the two metal nanolayers, which serve as thin metal electrodes for organic light-emitting microfilm between the layers.
A current-driven source of long-range surface plasmons (LRSPs) on a duplex metal nanolayer is reported. Electrical excitation of LRSPs was experimentally observed in a planar structure, where an organic light-emitting film was sandwiched between two metal nanolayers that served as electrodes. To achieve the LRSP propagation in these metal nanolayers at the interface with air, the light-emitting structure was bordered by a one-dimensional photonic crystal (PC) on the other side. The dispersion of the light emitted by such a hybrid PC/organic-light-emitting-diode structure (PC/OLED) comprising two thin metal electrodes was obtained, with a clearly identified LRSP resonance peak.
PDF
