scholarly journals Lipid droplets as endogenous intracellular microlenses

2021 ◽  
Vol 10 (1) ◽  
Author(s):  
Xixi Chen ◽  
Tianli Wu ◽  
Zhiyong Gong ◽  
Jinghui Guo ◽  
Xiaoshuai Liu ◽  
...  
Keyword(s):  
Optical Tweezers ◽  
Lipid Droplets ◽  
Incident Light ◽  
Extracellular Fluid ◽  
Excitation Power ◽  
Fluorescence Signal ◽  
Enhanced Fluorescence ◽  
Focusing Effect ◽  
Extracellular Signals ◽  
Single Cell Diagnosis

AbstractUsing a single biological element as a photonic component with well-defined features has become a new intriguing paradigm in biophotonics. Here we show that endogenous lipid droplets in the mature adipose cells can behave as fully biocompatible microlenses to strengthen the ability of microscopic imaging as well as detecting intra- and extracellular signals. By the assistance of biolenses made of the lipid droplets, enhanced fluorescence imaging of cytoskeleton, lysosomes, and adenoviruses has been achieved. At the same time, we demonstrated that the required excitation power can be reduced by up to 73%. The lipidic microlenses are finely manipulated by optical tweezers in order to address targets and perform their real-time imaging inside the cells. An efficient detecting of fluorescence signal of cancer cells in extracellular fluid was accomplished due to the focusing effect of incident light by the lipid droplets. The lipid droplets acting as endogenous intracellular microlenses open the intriguing route for a multifunctional biocompatible optics tool for biosensing, endoscopic imaging, and single-cell diagnosis.

scholarly journals Spontaneous transitions to enhanced fluorescence for GeV centers in a single microcrystalline diamond

2018 ◽  
Vol 190 ◽  
pp. 04012
Author(s):  
Natalia A. Lozing ◽  
Maxim G. Gladush ◽  
Ivan Yu. Eremchev ◽  
Eugeniy A. Ekimov ◽  
Andrey V. Naumov
Keyword(s):  
Continuous Wave ◽  
Incident Light ◽  
Theoretical Explanation ◽  
Dielectric Medium ◽  
Continuous Wave Laser ◽  
Enhanced Fluorescence ◽  
Colour Centres ◽  
Transient Regimes ◽  
Generalized System ◽  
Bright Luminescence

We propose a theoretical explanation of spontaneous transitions between dim and bright fluorescence intensity states observed experimentally in a microcrystal of diamond with germanium-vacancy colour centres driven by a continuous wave laser. We use a generalized system of optical Maxwell-Bloch equations derived for an emitter in an ensemble of motionless similar particles embedded in a dielectric medium, which is transparent for the incident light. A numerical analysis of transient regimes and several models of slow damping of the bright luminescence mode are reported.

scholarly journals Dynamic Analysis and Simulation of an Optically Levitated Rotating Ellipsoid Rotor in Liquid Medium

2021 ◽  
Author(s):  
Qi Zhu ◽  
Nan Li ◽  
Heming Su ◽  
Wenqiang Li ◽  
Huizhu Hu
Keyword(s):  
Dynamic Analysis ◽  
Liquid Medium ◽  
Optical Tweezers ◽  
Incident Light ◽  
Optical Trap ◽  
Future Research ◽  
Rotational Axis ◽  
Micron Particle ◽  
Three Degree Of Freedom ◽  
And Control

AbstractOptical trap, a circularly polarized laser beam can levitate and control the rotation of microspheres in liquid medium with high stiffness. Trapping force performs as confinement while the trapped particle can be analog to a liquid floated gyroscope with three degree-of-freedom. In this work, we analyzed the feasibility of applying optically levitated rotor in the system. We presented the dynamic analysis and simulation of an ellipsoid micron particle. The precession motion and nutation motion of a rotating ellipsoid probe particle in optical tweezers were performed. We also analyzed the attitude changes of an optically levitated ellipsoid when there was variation of the external torque caused by deviation of the incident light that was provided. Furthermore, the trail path of the rotational axis vertex and the stabilization process of a particle of different ellipticities were simulated. We compared the movement tendencies of particles of different shapes and analyzed the selection criteria of ellipsoid rotor. These analytical formulae and simulation results are applicable to the analysis of the rotational motion of particles in optical tweezers, especially to the future research of the gyroscope effect.

The Detection of a Fluorescent Dye by Surface-Enhanced Fluorescence with the Addition of Silver Nanoparticles and Its Application for the Space Station

2020 ◽  
Vol 20 (5) ◽  
pp. 3195-3200 ◽  
Author(s):  
Jian Wu ◽  
Yongjun Du ◽  
Chunyan Wang ◽  
Tao Chen
Keyword(s):  
Silver Nanoparticles ◽  
Fluorescence Detection ◽  
Microfluidic Chip ◽  
Fluorescent Dye ◽  
Fluorescence Signal ◽  
Fast Method ◽  
Dye Molecules ◽  
Enhanced Fluorescence ◽  
Surface Enhanced Fluorescence ◽  
Surface Enhanced

Surface-enhanced fluorescence detection has large potential for detecting many chemical and biological trace analytes. This paper presents a novel method for preparing silver nanomaterials in microfluidic chip channels for the surface-enhanced fluorescence detection of fluorescent dye (SYBR Green I) molecules. Microfluidic chip channels were fabricated by a 248-nm excimer laser. Silver nanoparticles (Ag-NPs) were prepared inside the microfluidic chip channels by directly heating the silver precursor solution. The influence of different temperatures on the sizes of the silver nanoparticles was studied. Then, the surface-enhanced fluorescence technology based on the microfluidic system was used to detect the fluorescent dye molecules. As a result, the fluorescence signal of the fluorescent dye molecules was significantly enhanced by the silver nanoparticles. In addition, the effect of particle size on the fluorescence signal was studied. This simple and fast method is suitable for a fluorescent PCR (polymerase chain reaction) system and has good application prospects for detecting harmful microorganisms in a spacecraft.

scholarly journals Recent Progress on Plasmon-Enhanced Fluorescence

Nanophotonics ◽  
2015 ◽  
Vol 4 (4) ◽  
pp. 472-490 ◽  
Author(s):  
Jun Dong ◽  
Zhenglong Zhang ◽  
Hairong Zheng ◽  
Mentao Sun
Keyword(s):  
Surface Plasmons ◽  
Single Molecule ◽  
Recent Progress ◽  
Radiative Decay ◽  
Fluorescence Signal ◽  
Enhanced Fluorescence ◽  
Fluorescence Measurements ◽  
Plasmon Enhanced Fluorescence ◽  
Early Results ◽  
Surface Enhanced

AbstractThe optically generated collective electron density waves on metal–dielectric boundaries known as surface plasmons have been of great scientific interest since their discovery. Being electromagnetic waves on gold or silver nanoparticle’s surface, localised surface plasmons (LSP) can strongly enhance the electromagnetic field. These strong electromagnetic fields near the metal surfaces have been used in various applications like surface enhanced spectroscopy (SES), plasmonic lithography, plasmonic trapping of particles, and plasmonic catalysis. Resonant coupling of LSPs to fluorophore can strongly enhance the emission intensity, the angular distribution, and the polarisation of the emitted radiation and even the speed of radiative decay, which is so-called plasmon enhanced fluorescence (PEF). As a result, more and more reports on surface-enhanced fluorescence have appeared, such as SPASER-s, plasmon assisted lasing, single molecule fluorescence measurements, surface plasmoncoupled emission (SPCE) in biological sensing, optical orbit designs etc. In this review, we focus on recent advanced reports on plasmon-enhanced fluorescence (PEF). First, the mechanism of PEF and early results of enhanced fluorescence observed by metal nanostructure will be introduced. Then, the enhanced substrates, including periodical and nonperiodical nanostructure, will be discussed and the most important factor of the spacer between molecule and surface and wavelength dependence on PEF is demonstrated. Finally, the recent progress of tipenhanced fluorescence and PEF from the rare-earth doped up-conversion (UC) and down-conversion (DC) nanoparticles (NPs) are also commented upon. This review provides an introduction to fundamentals of PEF, illustrates the current progress in the design of metallic nanostructures for efficient fluorescence signal amplification that utilises propagating and localised surface plasmons.

scholarly journals Three-Way Junction-Induced Isothermal Amplification with High Signal-to-Background Ratio for Detection of Pathogenic Bacteria

Sensors ◽  
2021 ◽  
Vol 21 (12) ◽  
pp. 4132
Author(s):  
Jung Ho Kim ◽  
Seokjoon Kim ◽  
Sung Hyun Hwang ◽  
Tae Hwi Yoon ◽  
Jung Soo Park ◽  
...  
Keyword(s):  
Nucleic Acid ◽  
Nucleic Acids ◽  
Pathogenic Bacteria ◽  
High Selectivity ◽  
Isothermal Amplification ◽  
Rna Aptamers ◽  
High Signal ◽  
Fluorescence Signal ◽  
Enhanced Fluorescence ◽  
Target Nucleic Acid

The consumption of water and food contaminated by pathogens is a major cause of numerous diseases and deaths globally. To control pathogen contamination and reduce the risk of illness, a system is required that can quickly detect and monitor target pathogens. We developed a simple and reproducible strategy, termed three-way junction (3WJ)-induced transcription amplification, to detect target nucleic acids by rationally combining 3WJ-induced isothermal amplification with a light-up RNA aptamer. In principle, the presence of the target nucleic acid generates a large number of light-up RNA aptamers (Spinach aptamers) through strand displacement and transcription amplification for 2 h at 37 °C. The resulting Spinach RNA aptamers specifically bind to fluorogens such as 3,5-difluoro-4-hydroxybenzylidene imidazolinone and emit a highly enhanced fluorescence signal, which is clearly distinguished from the signal emitted in the absence of the target nucleic acid. With the proposed strategy, concentrations of target nucleic acids selected from the genome of Salmonellaenterica serovar Typhi (S. Typhi) were quantitatively determined with high selectivity. In addition, the practical applicability of the method was demonstrated by performing spike-and-recovery experiments with S. Typhi in human serum.

scholarly journals Enhanced fluorescence signal in nonlinear microscopy through supplementary fiber-optic light collection

2009 ◽  
Vol 17 (8) ◽  
pp. 6421 ◽  
Author(s):  
Christoph J. Engelbrecht ◽  
Werner Göbel ◽  
Fritjof Helmchen
Keyword(s):  
Fiber Optic ◽  
Fluorescence Signal ◽  
Nonlinear Microscopy ◽  
Light Collection ◽  
Enhanced Fluorescence

scholarly journals Recent Developments in Plasmonic Nanostructures for Metal Enhanced Fluorescence-Based Biosensing

Nanomaterials ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 1749 ◽  
Author(s):  
Mohsin Ali Badshah ◽  
Na Yoon Koh ◽  
Abdul Wasy Zia ◽  
Naseem Abbas ◽  
Zahra Zahra ◽  
...  
Keyword(s):  
Forensic Science ◽  
Basic Mechanism ◽  
Medical Diagnostics ◽  
Plasmonic Nanostructures ◽  
Fluorescence Signal ◽  
Enhanced Fluorescence ◽  
Metal Enhanced Fluorescence ◽  
Research Areas ◽  
Design Flexibility ◽  
Recent Developments

Metal-enhanced fluorescence (MEF) is a unique phenomenon of surface plasmons, where light interacts with the metallic nanostructures and produces electromagnetic fields to enhance the sensitivity of fluorescence-based detection. In particular, this enhancement in sensing capacity is of importance to many research areas, including medical diagnostics, forensic science, and biotechnology. The article covers the basic mechanism of MEF and recent developments in plasmonic nanostructures fabrication for efficient fluorescence signal enhancement that are critically reviewed. The implications of current fluorescence-based technologies for biosensors are summarized, which are in practice to detect different analytes relevant to food control, medical diagnostics, and forensic science. Furthermore, characteristics of existing fabrication methods have been compared on the basis of their resolution, design flexibility, and throughput. The future projections emphasize exploring the potential of non-conventional materials and hybrid fabrication techniques to further enhance the sensitivity of MEF-based biosensors.

scholarly journals Fabrication of a Plasmonic Nanoantenna Array Using Metal Deposition on Polymer Nanoimprinted Nanodots for an Enhanced Fluorescence Substrate

Polymers ◽  
2020 ◽  
Vol 13 (1) ◽  
pp. 48
Author(s):  
Jun Kim ◽  
Naseem Abbas ◽  
Seongmin Lee ◽  
Jeongwoo Yeom ◽  
Md Ali Asgar ◽  
...  
Keyword(s):  
Electromagnetic Field ◽  
Enhancement Factor ◽  
Cost Effective ◽  
Localized Surface Plasmon ◽  
Fluorescence Signal ◽  
Enhanced Fluorescence ◽  
Maximum Enhancement ◽  
Geometrical Properties ◽  
Nanodot Array ◽  
Cost Effective Method

A simple and cost-effective method is proposed herein for a plasmonic nanoantenna array (PNAA) for the fabrication of metal-enhanced fluorescence (MEF) substrates in which fluorophores interact with the enhanced electromagnetic field generated by a localized surface plasmon to provide a higher fluorescence signal. The PNAA is fabricated by the deposition of a silver (Ag) layer on an ultraviolet (UV) nanoimprinted nanodot array with a pitch of 400 nm, diameter of 200 nm, and height of 100 nm. During deposition, raised Ag nanodisks and a lower Ag layer are, respectively, formed on the top and bottom of the imprinted nanodot array, and the gap between these Ag layers acts as a plasmonic nanoantenna. Since the thickness of the gap within the PNAA is influenced by the thickness of Ag deposition, the effects of the latter upon the geometrical properties of the fabricated PNAA are examined, and the electromagnetic field intensity distributions of PNAAs with various Ag thicknesses are simulated. Finally, the fluorescence enhancement factor (FEF) of the fabricated PNAA MEF substrate is measured using spotted Cy5-conjugated streptavidin to indicate a maximum enhancement factor of ~22× for the PNAA with an Ag layer thickness of 75 nm. The experimental results are shown to match the simulated results.

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