scholarly journals SARS-CoV-2 Detection using Colorimetric Plasmonic Sensors: A Proof-of-Concept Computational Study

2021 ◽  
Author(s):  
Somen Baidya ◽  
Ahmed M Hassan
Keyword(s):  
Gold Nanoparticles ◽  
Outer Surface ◽  
Near Infrared ◽  
Computational Study ◽  
Visible Spectrum ◽  
Resonance Wavelength ◽  
Infrared Region ◽  
Molecular Techniques ◽  
Visible Range ◽  
Broadband Absorption

Traditional molecular techniques for SARS-CoV-2 viral detection are time-consuming and can exhibit a high probability of false negatives. In this work, <a>we present a computational study of SARS-CoV-2 detection using plasmonic gold nanoparticles</a>. The resonance wavelength of a SARS-CoV-2 virus was recently estimated to be in the near-infrared region. By engineering gold nanospheres to specifically bind with the outer surface of the SARS-CoV-2 virus, the resonance frequency can be shifted to the visible range (380 nm – 700 nm). Moreover, we show that broadband absorption will emerge in the visible spectrum when the virus is partially covered with gold nanoparticles at a specific coverage percentage. This broadband absorption can be used to guide the development of an efficient and accurate colorimetric plasmon sensor for COVID-19 detection. Our observation also suggests that this technique is unaffected by the number of protein spikes present on the virus outer surface, hence can pave a potential path for a diagnostic tool independent on the number of protein spikes.

scholarly journals SARS-CoV-2 Detection using Colorimetric Plasmonic Sensors: A Proof-of-Concept Computational Study

2021 ◽  
Author(s):  
Somen Baidya ◽  
Ahmed M Hassan
Keyword(s):  
Gold Nanoparticles ◽  
Outer Surface ◽  
Near Infrared ◽  
Computational Study ◽  
Visible Spectrum ◽  
Resonance Wavelength ◽  
Infrared Region ◽  
Molecular Techniques ◽  
Visible Range ◽  
Broadband Absorption

Traditional molecular techniques for SARS-CoV-2 viral detection are time-consuming and can exhibit a high probability of false negatives. In this work, <a>we present a computational study of SARS-CoV-2 detection using plasmonic gold nanoparticles</a>. The resonance wavelength of a SARS-CoV-2 virus was recently estimated to be in the near-infrared region. By engineering gold nanospheres to specifically bind with the outer surface of the SARS-CoV-2 virus, the resonance frequency can be shifted to the visible range (380 nm – 700 nm). Moreover, we show that broadband absorption will emerge in the visible spectrum when the virus is partially covered with gold nanoparticles at a specific coverage percentage. This broadband absorption can be used to guide the development of an efficient and accurate colorimetric plasmon sensor for COVID-19 detection. Our observation also suggests that this technique is unaffected by the number of protein spikes present on the virus outer surface, hence can pave a potential path for a diagnostic tool independent on the number of protein spikes.

scholarly journals Spectroscopic detection of forest diseases: a review (1970–2020)

2021 ◽  
Author(s):  
Lorenzo Cotrozzi
Keyword(s):  
Early Detection ◽  
Optical Sensors ◽  
Near Infrared ◽  
Sustainable Forest Management ◽  
Visible Spectrum ◽  
Cost Effective ◽  
Infrared Region ◽  
Forest Disturbances ◽  
Effective Manner ◽  
Forest Diseases

AbstractSustainable forest management is essential to confront the detrimental impacts of diseases on forest ecosystems. This review highlights the potential of vegetation spectroscopy in improving the feasibility of assessing forest disturbances induced by diseases in a timely and cost-effective manner. The basic concepts of vegetation spectroscopy and its application in phytopathology are first outlined then the literature on the topic is discussed. Using several optical sensors from leaf to landscape-level, a number of forest diseases characterized by variable pathogenic processes have been detected, identified and quantified in many country sites worldwide. Overall, these reviewed studies have pointed out the green and red regions of the visible spectrum, the red-edge and the early near-infrared as the spectral regions most sensitive to the disease development as they are mostly related to chlorophyll changes and symptom development. Late disease conditions particularly affect the shortwave-infrared region, mostly related to water content. This review also highlights some major issues to be addressed such as the need to explore other major forest diseases and geographic areas, to further develop hyperspectral sensors for early detection and discrimination of forest disturbances, to improve devices for remote sensing, to implement long-term monitoring, and to advance algorithms for exploitation of spectral data. Achieving of these goals will enhance the capability of vegetation spectroscopy in early detection of forest stress and in managing forest diseases.

scholarly journals Computed Tomography Imaging Agent Based on Gold Nanoparticles for Internal Iliac Artery Embolization after Endovascular Abdominal Aortic Repair and CCN3 Protection Mechanism

2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
Siying Pei ◽  
Yao Sun ◽  
Dongxu Fan ◽  
Shuhua Deng ◽  
Haoran Mei ◽  
...  
Keyword(s):  
Gold Nanoparticles ◽  
Near Infrared ◽  
Infrared Region ◽  
Fluorescent Properties ◽  
Protection Mechanism ◽  
Abdominal Aortic ◽  
Infrared Rays ◽  
Growth Method ◽  
Internal Iliac ◽  
Endovascular Abdominal Aortic Repair

Abdominal aortic aneurysm is more stressful and has more complications in many diseases. During treatment and repair, arteriosclerosis, abdominal congestion deposition, and abdominal swelling cannot be eliminated. In this paper, we used the seed growth method to obtain gold nanoparticles (AuNPs) with good morphology and dispersion. The AuNPs of larger aspect ratio synthesized in this experiment moved their longitudinal plasmon resonance absorption peak to the near-infrared region, which provided suitable materials for subsequent experiments and laid the foundation for the photothermal therapy of tumors. Experiments show that near-infrared rays can penetrate into deep tissues to overcome the shortcomings that visible light cannot penetrate abdominal aorta well. AuNPs absorb near-infrared rays, thereby generating heat energy to achieve the purpose of treating tumors. In addition, AuNPs also have fluorescent properties, combined with other forms of imaging methods, to achieve the purpose of multimodal imaging, and improve the diagnostic accuracy of studying the protection mechanism of the nephroblastoma overexpressed (NOV or CCN3) gene.

scholarly journals Experimental setup for light-to-heat NIR conversion measurements of gold nano-particles’ solutions

2018 ◽  
Vol 5 (2) ◽  
pp. 38-47
Author(s):  
Nikolay Uzunov ◽  
Michele Bello ◽  
Laura Melendez-Alafort ◽  
Laura De Nardo
Keyword(s):  
Gold Nanoparticles ◽  
Near Infrared ◽  
Laser System ◽  
Fluorescence Emission ◽  
Ambient Air ◽  
Infrared Region ◽  
Nano Particles ◽  
Fixed Temperature ◽  
Electronic Temperature ◽  
Cuvette Holder

Abstract In recent years, there is a constantly increasing interest in the application of nanoparticles for cancer diagnosis and cancer therapy. In this respect, the most promising nano-objects at present are the gold nanoparticles. A very convenient and powerful property of these objects is their ability to increase their temperature under electro-magnetic irradiation with certain wavelength. In our research we have directed our efforts toward particular nano-objects specifically sensitive to electromagnetic radiation in the near-infrared region (NIR). In order to study the photothermic properties of the solutions of gold nanoparticles in the NIR we constructed a specific electronic setup consisting of a laser system with interchangeable laser diodes with different wavelength NIR light, a thermally-insulated cuvette-holder compartment with temperature measuring probes and a NIR spectrometer to control the stimulated fluorescence emission of the nanoparticles’ solutions. The temperature measurement compartment with the thermal-insulated cuvette holder was designed to maintain the solutions’ temperature at a fixed value right before the moment of laser irradiation. To maintain the measurement setup at a fixed temperature before the irradiation we used a thermal stabilized system based on two Peltier cells with electronic temperature control. The temperatures of the ambient air and the temperature of the cuvette walls were continuously measured in order to make corrections about the temperature dissipation during the irradiation.

scholarly journals Preliminary Assays towards Melanoma Cells Using Phototherapy with Gold-Based Nanomaterials

Nanomaterials ◽  
2020 ◽  
Vol 10 (8) ◽  
pp. 1536
Author(s):  
Joana Lopes ◽  
João Miguel Pinto Coelho ◽  
Pedro Manuel Cardoso Vieira ◽  
Ana Silveira Viana ◽  
Maria Manuela Gaspar ◽  
...  
Keyword(s):  
Gold Nanoparticles ◽  
Cell Lines ◽  
Complex Disease ◽  
Near Infrared ◽  
Infrared Region ◽  
Melanoma Cells ◽  
Therapeutic Window ◽  
New Paradigm ◽  
Skin Cells ◽  
Mean Size

Cancer like melanoma is a complex disease, for which standard therapies have significant adverse side effects that in most cases are ineffective and highly unspecific. Thus, a new paradigm has come with the need of achieving alternative (less invasive) and effective therapies. In this work, biocompatible gold nanoparticles (GNPs) coated with hyaluronic acid and oleic acid were prepared and characterized in terms of size, morphology and cytotoxicity in the presence of Saccharomyces cerevisiae, and two cell lines, the keratinocytes (healthy skin cells, HaCat) and the melanoma cells (B16F10). Results showed that these GNPs absorb within the near-infrared region (750–1400 nm), in the optical therapeutic window (from 650 to 1300 nm), in contrast to other commercial gold nanoparticles, which enables light to penetrate into deep skin layers. A laser emitting in this region was applied and its effect also analyzed. The coated GNPs showed a spherical morphology with a mean size of 297 nm without cytotoxic effects towards yeast and tested cell lines. Nevertheless, after laser irradiation, a reduction of 20% in B16F10 cell line viability was observed. In summary, this work appears to be a promising strategy for the treatment of non-metastatic melanoma or other superficial tumors.

scholarly journals White light generation using photonic crystal fiber with sub-micron circular lattice

2017 ◽  
Vol 68 (4) ◽  
pp. 282-289 ◽  
Author(s):  
Hamed Saghaei ◽  
Ashkan Ghanbari
Keyword(s):  
Photonic Crystal ◽  
Photonic Crystal Fiber ◽  
White Light ◽  
Near Infrared ◽  
Metabolic Response ◽  
Stimulated Raman Scattering ◽  
Infrared Region ◽  
Visible Range ◽  
Crystal Fiber ◽  
White Light Generation

AbstractIn this paper, we study a photonic crystal fiber (PCF) with circular lattice and engineer linear and nonlinear parameters by varying the diameter of air-holes. It helps us obtain low and high zero dispersion wavelengths in the visible and nearinfrared regions. We numerically demonstrate that by launching 100 fs input pulses of 1, 2, and 5 kW peak powers with center wavelength of 532 nm from an unamplified Ti:sapphire laser into a 100 mm length of the engineered PCF, supercontinua as wide as 290, 440 and 830 nm can be obtained, respectively. The spectral broadening is due to the combined action of self-phase modulation, stimulated Raman scattering and parametric four-wave-mixing generation of the pump pulses. The third and the widest spectrum covers the entire visible range and a part of near infrared region making it a suitable source for both white light applications and optical coherence tomography to measure retinal oxygen metabolic response to systemic oxygenation.

Optical properties of potassium acid phthalate

1997 ◽  
Vol 12 (5) ◽  
pp. 1262-1267 ◽  
Author(s):  
Davide Comoretto ◽  
Laura Rossi ◽  
Alessandro Borghesi
Keyword(s):  
Optical Properties ◽  
Near Infrared ◽  
Normal Incidence ◽  
Infrared Region ◽  
Visible Range ◽  
Direct Inversion ◽  
Potassium Acid Phthalate ◽  
Absolute Reflectance ◽  
Reflectance Measurements ◽  
Acid Phthalate

Potassium acid phthalate (KAP) crystals are promising as substrates for the growth of highly oriented films of conjugated polymers with exceedingly high and fast nonlinear optical response. We report the KAP optical properties (real and imaginary parts of the refractive index ñ = n + ik) in the near infrared and visible range deduced by ellipsometric measurements and direct inversion of transmittance and near-normal incidence absolute reflectance measurements. In the infrared region n was also deduced by the interference fringes.

scholarly journals SERS, XPS and DFT Study of Xanthine Adsorbed on Citrate-Stabilized Gold Nanoparticles

Sensors ◽  
2019 ◽  
Vol 19 (12) ◽  
pp. 2700 ◽  
Author(s):  
Stefano Caporali ◽  
Francesco Muniz-Miranda ◽  
Alfonso Pedone ◽  
Maurizio Muniz-Miranda
Keyword(s):  
Gold Nanoparticles ◽  
Photoelectron Spectroscopy ◽  
Active Sites ◽  
Density Functional ◽  
Near Infrared ◽  
Fluorescence Emission ◽  
Colloidal Suspensions ◽  
Infrared Region ◽  
Chloride Ions ◽  
Surface Enhanced Raman

We have studied the adsorption of xanthine, a nucleobase present in human tissue and fluids that is involved in important metabolic processes, on citrate-reduced gold colloidal nanoparticles by means of surface-enhanced Raman scattering (SERS), absorption, and X-ray photoelectron spectroscopy (XPS) measurements, along with density functional theory (DFT) calculations. The citrate anions stabilize the colloidal suspensions by strongly binding the gold nanoparticles. However, these anions do not impair the adsorption of xanthine on positively-charged active sites present on the metal surface. We have obtained the Fourier transform (FT)-SERS spectra of adsorbed xanthine by laser excitation in the near infrared spectral region, where interference due to fluorescence emission does not usually occur. In fact, the addition of chloride ions to the Au/xanthine colloid induces the aggregation of the gold nanoparticles, whose plasmonic band is shifted to the near infrared region where there is the exciting laser line of the FT–Raman instrument. Hence, this analytical approach is potentially suitable for spectroscopic determination of xanthine directly in body fluids, avoiding fluorescence phenomena induced by visible laser irradiation.

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