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.

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 Experimental setup for light-to-heat NIR conversion measurements of gold nanoparticle solutions

2019 ◽  
Vol 6 (1) ◽  
pp. 91-99
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 ◽  
Fixed Temperature ◽  
Electronic Temperature ◽  
Cuvette Holder ◽  
Electro Magnetic

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 nanoparticle 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 Dermacozine N, the First Natural Linear Pentacyclic Oxazinophenazine with UV–Vis Absorption Maxima in the Near Infrared Region, Along with Dermacozines O and P Isolated from the Mariana Trench Sediment Strain Dermacoccus abyssi MT 1.1T

Marine Drugs ◽  
2021 ◽  
Vol 19 (6) ◽  
pp. 325
Author(s):  
Bertalan Juhasz ◽  
Dawrin Pech-Puch ◽  
Jioji N. Tabudravu ◽  
Bastien Cautain ◽  
Fernando Reyes ◽  
...  
Keyword(s):  
Linear Regression ◽  
Density Functional ◽  
Near Infrared ◽  
Linear Regression Analysis ◽  
2D Nmr ◽  
Multiple Linear Regression Analysis ◽  
Infrared Region ◽  
Cellular Level ◽  
Mariana Trench ◽  
Uv Visible

Three dermacozines, dermacozines N–P (1–3), were isolated from the piezotolerant Actinomycete strain Dermacoccus abyssi MT 1.1T, which was isolated from a Mariana Trench sediment in 2006. Herein, we report the elucidation of their structures using a combination of 1D/2D NMR, LC-HRESI-MSn, UV–Visible, and IR spectroscopy. Further confirmation of the structures was achieved through the analysis of data from density functional theory (DFT)–UV–Visible spectral calculations and statistical analysis such as two tailed t-test, linear regression-, and multiple linear regression analysis applied to either solely experimental or to experimental and calculated 13C-NMR chemical shift data. Dermacozine N (1) bears a novel linear pentacyclic phenoxazine framework that has never been reported as a natural product. Dermacozine O (2) is a constitutional isomer of the known dermacozine F while dermacozine P (3) is 8-benzoyl-6-carbamoylphenazine-1-carboxylic acid. Dermacozine N (1) is unique among phenoxazines due to its near infrared (NIR) absorption maxima, which would make this compound an excellent candidate for research in biosensing chemistry, photodynamic therapy (PDT), opto-electronic applications, and metabolic mapping at the cellular level. Furthermore, dermacozine N (1) possesses weak cytotoxic activity against melanoma (A2058) and hepatocellular carcinoma cells (HepG2) with IC50 values of 51 and 38 μM, respectively.

scholarly journals Stable and tunable plasmon resonance of molybdenum oxide nanosheets from the ultraviolet to the near-infrared region for ultrasensitive surface-enhanced Raman analysis

2019 ◽  
Vol 10 (25) ◽  
pp. 6330-6335 ◽  
Author(s):  
Jinhu Wang ◽  
Yinhua Yang ◽  
Hua Li ◽  
Jun Gao ◽  
Ping He ◽  
...  
Keyword(s):  
Near Infrared ◽  
Infrared Region ◽  
Raman Analysis ◽  
Surface Protection ◽  
Surface Enhanced ◽  
Color Tunable ◽  
Surface Enhanced Raman ◽  
Heavily Doped ◽  
Near Infrared Region ◽  
Preparation Strategy

Preparation of color-tunable and stable plasmonic MoO3 nanomaterials remains challenging, due to the lack of an effective preparation strategy and surface protection in heavily doped MoO3.

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.

Single crystal polarized spectra in the near-infrared region: a local-mode analysis of the spectra of CsMnCl3•2X2O (X = H, D)

1994 ◽  
Vol 72 (5) ◽  
pp. 1211-1217 ◽  
Author(s):  
Ian M. Walker ◽  
Paul J. McCarthy
Keyword(s):  
Hydrogen Bond ◽  
Near Infrared ◽  
Infrared Region ◽  
Chloride Ions ◽  
Mode Analysis ◽  
Local Mode ◽  
Local Modes ◽  
Near Infrared Spectra ◽  
Parameter Values ◽  
Local Mode Analysis

Polarized near-infrared spectra of single crystals of CsMnCl3•2X2O (X = H, D) were recorded at 10 K. Those bands which could be assigned to O—H or O—D stretch overtones were analyzed using local-mode theory specifically adapted for systems having less than C2v symmetry. Both O—H oscillators form nearly linear hydrogen bonds to neighboring chloride ions at different distances. As a result, the local-mode harmonic frequency and anharmonicity parameters show characteristic shifts from their gas-phase values. The parameter values cover an unusually narrow range in this crystal, considering the spread in hydrogen-bond distances. Assignment of stretch overtone bands to specific oscillators in the crystal was made by using the polarization behavior expected of local modes in the oriented gas model. Several of the overtone bands show combinations with lattice modes or low-energy hydrogen-bond modes in unusual detail.

scholarly journals CCCCC pentadentate chelates with planar Möbius aromaticity and unique properties

2016 ◽  
Vol 2 (8) ◽  
pp. e1601031 ◽  
Author(s):  
Congqing Zhu ◽  
Caixia Yang ◽  
Yongheng Wang ◽  
Gan Lin ◽  
Yuhui Yang ◽  
...  
Keyword(s):  
Photothermal Therapy ◽  
Density Functional ◽  
Near Infrared ◽  
Chelating Agent ◽  
Density Functional Theory Calculations ◽  
Infrared Region ◽  
Carbon Chain ◽  
Broad Absorption ◽  
Functional Theory ◽  
Potential Applications

The coordinating atoms in polydentate chelates are primarily heteroatoms. We present the first examples of pentadentate chelates with all binding atoms of the chelating agent being carbon atoms, denoted as CCCCC chelates. Having up to five metal-carbon bonds in the equatorial plane has not been previously observed in transition metal chemistry. Density functional theory calculations showed that the planar metallacycle has extended Craig-Möbius aromaticity arising from 12-center–12-electron dπ-pπ π-conjugation. These planar chelates have broad absorption in the ultraviolet-visible–near-infrared region and, thus, notable photothermal performance upon irradiation by an 808-nm laser, indicating that these chelates have potential applications in photothermal therapy. The combination of facile synthesis, high stability, and broad absorption of these complexes could make the polydentate carbon chain a novel building block in coordination chemistry.

scholarly journals Supported Gold Nanoparticles as Catalysts in Peroxidative and Aerobic Oxidation of 1-Phenylethanol under Mild Conditions

Nanomaterials ◽  
2020 ◽  
Vol 10 (1) ◽  
pp. 151 ◽  
Author(s):  
Ekaterina Pakrieva ◽  
Ana P. C. Ribeiro ◽  
Ekaterina Kolobova ◽  
Luísa M. D. R. S. Martins ◽  
Sónia A. C. Carabineiro ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Active Sites ◽  
Density Functional ◽  
Aerobic Oxidation ◽  
Reaction Conditions ◽  
Tert Butyl Hydroperoxide ◽  
Temperature Programmed ◽  
Pretreatment Atmosphere ◽  
Supported Gold Nanoparticles ◽  
Supported Gold

The efficiency of Au/TiO2 based catalysts in 1-phenylethanol oxidation was investigated. The role of support modifiers (La2O3 or CeO2), influence of gold loading (0.5% or 4%) and redox pretreatment atmosphere, catalyst recyclability, effect of oxidant: tert-butyl hydroperoxide (TBHP) or O2, as well as the optimization of experimental parameters of the reaction conditions in the oxidation of this alcohol were studied and compared with previous studies on 1-octanol oxidation. Samples were characterized by temperature-programmed oxygen desorption (O2-TPD) method. X-ray photoelectron spectroscopy (XPS) measurements were carried out for used catalysts to find out the reason for deactivation in 1-phenylethanol oxidation. The best catalytic characteristics were shown by catalysts modified with La2O3, regardless of the alcohol and the type of oxidant. When O2 was used, the catalysts with 0.5% Au, after oxidative pretreatment, showed the highest activity in both reactions. The most active catalysts in 1-phenylethanol oxidation with TBHP were those with 4% Au and the H2 treatment, while under the same reaction conditions, 0.5% Au and O2 treatment were beneficial in 1-octanol oxidation. Despite the different chemical nature of the substrates, it seems likely that Au+(Auδ+) act as the active sites in both oxidative reactions. Density functional theory (DFT) simulations confirmed that the gold cationic sites play an essential role in 1-phenylethanol adsorption.

A Novel Near-Infrared Fluorescence Sensor for H2O2 Based on N-Acetyl-L-Cysteine-Capped Gold Nanoparticles

2017 ◽  
Vol 46 ◽  
pp. 234-240
Author(s):  
Wen Juan Dong ◽  
Ji Yan Han ◽  
Xin Wu ◽  
Li Fan ◽  
Wen Ting Liang
Keyword(s):  
Hydrogen Peroxide ◽  
Gold Nanoparticles ◽  
Fluorescence Quenching ◽  
Near Infrared ◽  
Fluorescence Probe ◽  
Fluorescence Emission ◽  
Excitation Wavelength ◽  
Experimental Conditions ◽  
Time Resolved ◽  
Near Infrared Fluorescence

A novel near-infrared fluorescence quenching method has been developed for the determination of hydrogen peroxide based on N-acetyl-L-cysteine-capped gold nanoparticles (NAC-AuNPs) as a fluorescence probe. The prepared gold nanoparticles with the size of about 1.91 nm exhibited strong near-infrared fluorescence emission at 693 nm with excitation wavelength at 450 nm in aqueous solution. The fluorescence intensity of NAC-AuNPs was quenched dramatically by adding hydrogen peroxide. Therefore, it could be used to detect hydrogen peroxide based on the fluorescence quenching intensity was linear with the concentration of hydrogen peroxide. Under the optimal experimental conditions, the linear range and detection limit were 1.0×10-6 –3.0×10-2 mol/L and 1.0×10-7 mol/L, respectively. The possible quenching mechanism was investigated by time-resolved fluorescence spectroscopy. The proposed method was simple, sensitive and showed good repeatability and stability.

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