Improvement of LOD in Fluorescence Detection with Spectrally Nonuniform Background by Optimization of Emission Filtering

Galievsky, Victor A.; Stasheuski, Alexander S.; Krylov, Sergey N.

doi:10.1021/acs.analchem.7b03400

Cited by 31 publications

(26 citation statements)

References 34 publications

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“…Therefore, when the design of an analytical microsystem based on fluorescence detection is attempted, the Stokes shift and the quantum yield of the molecule are fundamental prerequisites to be considered in order to properly identify the most suitable detection scheme, filtration elements, and light detector. The noise sources in optofluidic fluorescence-based sensors originate from both optical (shot and flicker components) and non-optical elements (dark noise of the detector) [ 29 ]. The optical background noise may originate from components with different spectra, e.g., other fluorophores, scattering light, and autofluorescence.…”

Section: Methodsmentioning

confidence: 99%

Optofluidic Formaldehyde Sensing: Towards On-Chip Integration

Măriuța

Govindaraji²,

Colin

et al. 2020

Micromachines

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Formaldehyde (HCHO), a chemical compound used in the fabrication process of a broad range of household products, is present indoors as an airborne pollutant due to its high volatility caused by its low boiling point ( T = − 19 °C). Miniaturization of analytical systems towards palm-held devices has the potential to provide more efficient and more sensitive tools for real-time monitoring of this hazardous air pollutant. This work presents the initial steps and results of the prototyping process towards on-chip integration of HCHO sensing, based on the Hantzsch reaction coupled to the fluorescence optical sensing methodology. This challenge was divided into two individually addressed problems: (1) efficient airborne HCHO trapping into a microfluidic context and (2) 3,5–diacetyl-1,4-dihydrolutidine (DDL) molecular sensing in low interrogation volumes. Part (2) was addressed in this paper by proposing, fabricating, and testing a fluorescence detection system based on an ultra-low light Complementary metal-oxide-semiconductor (CMOS) image sensor. Two three-layer fluidic cell configurations (quartz–SU-8–quartz and silicon–SU-8–quartz) were tested, with both possessing a 3.5 µL interrogation volume. Finally, the CMOS-based fluorescence system proved the capability to detect an initial 10 µg/L formaldehyde concentration fully derivatized into DDL for both the quartz and silicon fluidic cells, but with a higher signal-to-noise ratio (SNR) for the silicon fluidic cell ( S N R s i l i c o n = 6.1 ) when compared to the quartz fluidic cell ( S N R q u a r t z = 4.9 ). The signal intensity enhancement in the silicon fluidic cell was mainly due to the silicon absorption coefficient at the excitation wavelength, a ( λ a b s = 420 nm ) = 5 × 10 4 cm − 1 , which is approximately five times higher than the absorption coefficient at the fluorescence emission wavelength, a ( λ e m = 515 nm ) = 9.25 × 10 3 cm − 1 .

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Section: Methodsmentioning

confidence: 99%

Optofluidic Formaldehyde Sensing: Towards On-Chip Integration

Măriuța

Govindaraji²,

Colin

et al. 2020

Micromachines

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“…All CE experiments were performed with a P/ACE MDQ apparatus (SCIEX, Concord, ON, Canada) equipped with a LIF detection system. Fluorescence was excited with a blue line (488 nm) of a solid‐state laser and detected at 520 nm using a spectrally optimized emission filter system . Uncoated fused‐silica capillaries, with a total length of 50 cm and a 10.2 cm distance from one of the ends to the detection zone were used.…”

Section: Methodsmentioning

confidence: 99%

Ideal‐filter capillary electrophoresis: A highly efficient partitioning method for selection of protein binders from oligonucleotide libraries

Krylova

Krylov

2019

Electrophoresis

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Selection of affinity ligands for protein targets from oligonucleotide libraries currently involves multiple rounds of alternating steps of partitioning of protein‐bound oligonucleotides (binders) from protein‐unbound oligonucleotides (nonbinders). We have recently introduced ideal‐filter capillary electrophoresis (IFCE) for binder selection in a single step of partitioning. In IFCE, protein‐binder complexes and nonbinders move inside the capillary in the opposite directions, and the efficiency of their partitioning reaches 109, i.e., only one of a billion molecules of nonbinders leaks through IFCE while all binders pass through. The condition of IFCE can be satisfied when the magnitude of the mobility of EOF is smaller than that of the protein‐binder complexes and larger than that of nonbinders. The efficiency of partitioning in IFCE is 10 million times higher than those of solid‐phase‐based methods of partitioning typically used in selection of affinity ligands for protein targets from oligonucleotide libraries. Here, we provide additional details on our justification for IFCE development. We elaborate on electrophoretic aspects of the method and define the theoretical range of EOF mobilities that support IFCE. Based on these theoretical results, we identify an experimental range of background electrolyte's ionic strength that supports IFCE. We also extend our interpretation of the results and discuss in‐depth IFCE's prospective in practical applications and fundamental studies.

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“…In the case of a uniform background signal (save for the excitation wavelength), maximum signal-to-noise ratio(S/N) is typically achieved with the widest-range filter that captures the spectral range where the desired signal remains above the average S/N, yet still effectively blocks the excitation. In the case of frequently encountered non-spectrally-uniform background signals, choosing the optimal excitation/emission filters is more challenging and the subject of ongoing research [ 64 ].…”

Section: Zero-mode Waveguide Backgroundmentioning

confidence: 99%

Zero-mode waveguide nanophotonic structures for single molecule characterization

Crouch

Han

Bohn

2018

J. Phys. D: Appl. Phys.

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Single-molecule characterization has become a crucial research tool in the chemical and life sciences, but limitations, such as limited concentration range, inability to control molecular distributions in space, and intrinsic phenomena, such as photobleaching, present significant challenges. Recent developments in non-classical optics and nanophotonics offer promising routes to mitigating these restrictions, such that even low affinity ( K D ~ mM) biomolecular interactions can be studied. Here we introduce and review specific nanophotonic devices used to support single molecule studies. Optical nanostructures, such as zero-mode waveguides (ZMWs), are usually fabricated in thin gold or aluminum films and serve to confine the observation volume of optical microspectroscopy to attoliter to zeptoliter volumes. These simple nanostructures allow individual molecules to be isolated for optical and electrochemical analysis, even when the molecules of interest are present at high concentration (μM - mM) in bulk solution. Arrays of ZMWs may be combined with optical probes such as single molecule fluorescence, single molecule fluorescence resonance energy transfer (smFRET), and fluorescence correlation spectroscopy (FCS) for distributed analysis of large numbers of single-molecule reactions or binding events in parallel. Furthermore, ZMWs may be used as multifunctional devices, for example by combining optical and electrochemical functions in a single discrete architecture to achieve electrochemical ZMWs (E-ZMW). In this review, we will describe the optical properties, fabrication, and applications of ZMWs for single-molecule studies, as well as the integration of ZMWs into systems for chemical and biochemical analysis.

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Improvement of LOD in Fluorescence Detection with Spectrally Nonuniform Background by Optimization of Emission Filtering

Cited by 31 publications

References 34 publications

Optofluidic Formaldehyde Sensing: Towards On-Chip Integration

Optofluidic Formaldehyde Sensing: Towards On-Chip Integration

Ideal‐filter capillary electrophoresis: A highly efficient partitioning method for selection of protein binders from oligonucleotide libraries

Zero-mode waveguide nanophotonic structures for single molecule characterization

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