Diffuse Reflectance Method Research Articles

Growth and improved properties of single crystal α-LiIO3 doped with amino acids

In this study, the effect of doping the amino acids L-arginine and L-nitroarginine on α-LiIO3 single crystal were presented. Bulk crystals were grown both from solutions doped with L-arginine and L-nitroarginine and from pure solution of α-LiIO3.When doped with L-arginine and L-nitroarginine the optical quality of the crystals was improved and growth rate was increased. These grown crystals were studied by single-crystal X-ray diffraction, IR and UV–Vis spectroscopy, Vickers microhardness, diffuse reflection, and second harmonic generation methods. Studies of microhardness and nonlinear optical activity showed that the properties of α-LiIO3 crystals were improved in the presence of L-arginine and L-nitroarginine. UV–Vis transmittance was improved in the presence of L-arginine (range 370–800 nm) and L-nitroarginine (range 290–370 nm). The second harmonic generation activity of the crystals α-LiIO3 grown with L-arginine (1.16 times) and L-nitroarginine (1.18 times) dopants is higher than that of pure α-LiIO3. The energy of the band gap increases by 1.2 times in the case of arginine dopants, and it decreases by 1.37 times in the case of the nitroarginine dopants, compared to that for the pure α-LiIO3.

Influence of recrystallization process on ionic conductivity of Ag6.75P0.25Ge0.75S5I based ceramic materials

This paper presents the results of research on ceramic materials based on Ag6.75(P0.25Ge0.75)S5I nanopowders with different grain size. Nanopowders with an average grain size of ∼100 and ∼160 nm, obtained by ball mill grinding, were characterized by XRD, SEM and diffuse reflectance methods. Ag6.75(P0.25Ge0.75)S5I ceramic samples were obtained by annealing pre-pressed disks at a pressure of 400 MPa. The microstructure and chemical composition of the obtained Ag6.75(P0.25Ge0.75)S5I ceramics were determined by SEM and EDS methods. The prepared Ag6.75(P0.25Ge0.75)S5I ceramics are chemically homogeneous with an average crystallite size of ∼1.99 and ∼2.29 μm and a low porosity of ∼6.4%. The electrical parameters of the investigated ceramics were characterized by the electrochemical impedance spectroscopy method. For both ceramics, there is an increase in total electrical conductivity with increasing frequency. It was established that the values of ionic conductivity of nanoceramic samples exceed the corresponding value of the bulk single crystalline sample. The influence of the recrystallization process and grain size on the electrical parameters of Ag6.75(P0.25Ge0.75)S5I ceramics is explained.

Formation and Structure Research of a Molecular Conjugate in the L-Ascorbic Acid – Isomaltite System

The formation of L-ascorbic acid molecular complexes with various biologically active substances opens the way to the production of a new drug type promising for the pharmaceutical, food and cosmetic industries use. The research concerns the possibility study of obtaining a conjugate of L-ascorbic acid with isomaltite in an aqueous ethanol (40 %) medium. The method of the target product isolating involves thermostating a solution containing equimolar amounts (0.001 mmol) of components (50 °C, 1 hour), followed by slow solvent removal for 24 hours (25 °C). The authors examined formation processes dynamics by molecular spectroscopy methods through sequential sampling. The optical density values at 350 Nm in the electronic spectra and 1,674 and 1,754 cm−1 bands position in the IR-Fourier solution spectra indicate the components destruction absence during thermostate control. When treated with carbon tetrachloride or diethyl ether, the syrupy mass obtained after solvent removal containing significant solvent amounts crystallizes a yellowish powder (0.32 g, ice point at 146.6 °C). A man studied its structure by the IR-Fourier spectroscopy. The authors recorded the spectra in the transmission mode (in the KBr tablets) and using the diffusion reflection method enabling to record changes in the absorption bands characteristic positions of the molecular complex formation. The transmission spectra of the high-frequency area indicate the 1-O-glycosylated isomaltite component involvement in the conjugation with ascorbic acid. The shifts of the C=C, C−O and C−O−H bond oscillation bands in the diffusion reflection spectrum of the isolated product relative to their position in the initial component spectra in the low-frequency area indicate the endiol ascorbic acid fragment interaction with the secondary OH groups of the acyclic isomaltite component. Structural analogues of the studied molecular conjugate are promising antioxidant preparations. This determines the further study relevance of its properties.

INFLUENCE OF IONIZING RADIATION ON THE DIFFUSE REFLECTION SPECTRA OF STEATITE CERAMICS SNC

In this article, the radiation defects induced in steatite ceramics type- SNC- irradiated with high doses of gamma-rays of 60Co source and mixed reactor nо-gamma-irradiation were studied using optical spectroscopy, i.e. diffuse reflection method. An analysis of the results of the diffuse reflection spectra showed that some structural defects are formed under gamma-irradiation. These are oxygen vacancies, unbound oxygen atoms, and E1 -centers (a three-coordinated silicon atom that has captured an electron) in the ultraviolet region of the spectrum. In the visible region of the spectrum, the types of hole centers are different. After decomposing the spectrum of the visible region into Gaussians, it was found that in this region of the spectrum, with no –gamma- irradiation of the reactor, in comparison with gamma-irradiation, various types of hole centers - (O-Me, Me-metal) are additionally formed. The efficiency of creating these structural defects in nо-gamma-reactor irradiated samples was higher compared to gamma irradiated samples.

Diffuse reflectance spectroscopy characterises the functional chemistry of soil organic carbon in agricultural soils

AbstractSoil organic carbon (SOC) originates from a complex mixture of organic materials, and to better understand its role in soil functions, one must characterise its chemical composition. However, current methods, such as solid‐state 13C nuclear magnetic resonance (NMR) spectroscopy, are time‐consuming and expensive. Diffuse reflectance spectroscopy in the visible, near infrared and mid‐infrared regions (vis–NIR: 350–2500 nm; mid‐IR: 4000–400 cm−1) can also be used to characterise SOC chemistry; however, it is difficult to know the frequencies where the information occurs. Thus, we correlated the C functional groups from the 13C NMR to the frequencies in the vis–NIR and mid‐IR spectra using two methods: (1) 2‐dimensional correlations of 13C NMR spectra and the diffuse reflectance spectra, and (2) modelling the NMR functional C groups with the reflectance spectra using support vector machines (SVM) (validated using 5 times repeated 10‐fold cross‐validation). For the study, we used 99 mineral soils from the agricultural regions of Sweden. The results show clear correlations between organic functional C groups measured with NMR and specific frequencies in the vis–NIR and mid‐IR spectra. While the 2D correlations showed general relationships (mainly related to the total SOC content), analysing the importance of the wavelengths in the SVM models revealed more detail. Generally, models using mid‐IR spectra produced slightly better estimates than the vis–NIR. The best estimates were for the alkyl C group (R2 = 0.83 and 0.85, vis–NIR and mid‐IR, respectively), and the O/N‐alkyl C group was the most difficult to estimate (R2 = 0.34 and 0.38, vis–NIR and mid‐IR, respectively). Combining 13C NMR with the cost‐effective diffuse reflectance methods could potentially increase the number of measured samples and improve the spatial and temporal characterisation of SOC. However, more studies with a wider range of soil types and land management systems are needed to further evaluate the conditions under which these methods could be used.Highlights Diffuse reflectance spectroscopy was used to characterise and model SOC functional chemistry. NMR derived C functional groups could be modelled with vis‐NIR and mid‐IR diffuse reflectance spectra. The methods allow for characterisation of SOC chemical composition on whole mineral soil samples. The approach can improve the spatial and temporal characterisation of SOC composition.

Simultaneous Noninvasive Detection and Therapy of Atherosclerosis Using HDL Coated Gold Nanorods.

Cardiovascular disease (CVD) is a major cause of death and disability worldwide. A real need exists in the development of new, improved therapeutic methods for treating CVD, while major advances in nanotechnology have opened new avenues in this field. In this paper, we report the use of gold nanoparticles (GNPs) coated with high-density lipoprotein (HDL) (GNP-HDL) for the simultaneous detection and therapy of unstable plaques. Based on the well-known HDL cardiovascular protection, by promoting the reverse cholesterol transport (RCT), injured rat carotids, as a model for unstable plaques, were injected with the GNP-HDL. Noninvasive detection of the plaques 24 h post the GNP injection was enabled using the diffusion reflection (DR) method, indicating that the GNP-HDL particles had accumulated in the injured site. Pathology and noninvasive CT measurements proved the recovery of the injured artery treated with the GNP-HDL. The DR of the GNP-HDL presented a simple and highly sensitive method at a low cost, resulting in simultaneous specific unstable plaque diagnosis and recovery.

Development of a diffuse reflectance probe for in situ measurement of inherent optical properties in sea ice

Abstract. Detailed characterization of the spatially and temporally varying inherent optical properties (IOPs) of sea ice is necessary to better predict energy and mass balances, as well as ice-associated primary production. Here we present the development of an active optical probe to measure IOPs of a small volume of sea ice (dm3) in situ and non-destructively. The probe is derived from the diffuse reflectance method used to measure the IOPs of human tissues. The instrument emits light into the ice by the use of an optical fibre. Backscattered light is measured at multiple distances away from the source using several receiving fibres. Comparison to a Monte Carlo simulated lookup table allows, in theory, retrieval of the absorption coefficient, the reduced scattering coefficient and a phase function similarity parameter γ, introduced by Bevilacqua and Depeursinge (1999). γ depends on the two first moments of the Legendre polynomials, allowing the analysis of the backscattered light not satisfying the diffusion regime. The depth reached into the medium by detected photons was estimated using Monte Carlo simulations: the maximum depth reached by 95 % of the detected photons was between 40±2 and 270±20 mm depending on the source–detector distance and on the ice scattering properties. The magnitude of the instrument validation error on the reduced scattering coefficient ranged from 0.07 % for the most scattering medium to 35 % for the less scattering medium over the 2 orders of magnitude we validated. Fixing the absorption coefficient and γ, which proved difficult to measure, vertical profiles of the reduced scattering coefficient were obtained with decimetre resolution on first-year Arctic interior sea ice on Baffin Island in early spring 2019. We measured values of up to 7.1 m−1 for the uppermost layer of interior ice and down to 0.15±0.05 m−1 for the bottommost layer. These values are in the range of polar interior sea ice measurements published by other authors. The inversion of the reduced scattering coefficient at this scale was strongly dependent on the value of γ, highlighting the need to define the higher moments of the phase function. This newly developed probe provides a fast and reliable means for measurement of scattering in sea ice.

Formation of 1D coordination polymers by reaction of a tetrazine ligand and PbX2 (X: Br, I) salts: Spectral, structural and theoretical studies

Two lead(II) 1D-coordination polymers, [Pb3(μ-BPTZ)2(μ4-Br)(μ3-Br)(μ-Br)3Br]n (1) (BPTZ = 3,6-di(pyridin-2-yl)-1,2,4,5-tetrazine) and [Pb(HPMPHz)(μ-I)2]n (2) (HPMPHz = zwitterionic form of N-(pyridin-2-ylmethylene)picolinohydrazonic acid, HPMPH) were prepared and identified by elemental analysis, FT-IR spectroscopy and single-crystal X-ray diffraction. The crystal structure of 1, is the first example for coordination of a tetrazine ligand to the lead(II) ion. The 1D chain in 1 is expanding by BPTZ and bromide bridges. Three different coordination environments were found for lead atoms: PbN4(μ4-Br)(μ3-Br)(μ-Br)2 with cube geometry; PbN2(μ4-Br)(μ3-Br)(μ2-Br)Br and PbN2(μ4-Br)(μ3-Br)2(μ2-Br)2 with capped octahedral geometries. Ligands around these lead(II) ions are arranged in hemidirected mode. X-ray analysis of 2 revealed a ring opening hydrolysis reaction that converts BPTZ ligand to the HPMPHz. This structure is the first example for a PbN2OI4 coordination environment which is extended by iodide bridges and contains hemidirected pentagonal bipyramidal coordinated lead(II) ions. Also 2 is the first example containing zwitterionic form of HPMPH. In the crystal network of the complexes, in addition to hydrogen bonds there are π–π stacking interactions between pyridine rings. Optical properties of the compound 1 were investigated by UV–Vis diffuse reflectance and emission spectroscopy methods in solid state. According to the DFT calculated electronic band structures, the compounds are indirect band gap semiconductors. Linear optical properties of the compounds (including the dielectric function, absorption coefficient, reflectivity, refractive index, optical conductivity and energy loss function) are also investigated by DFT method.

Cadmium copper selenite chloride, CdCu2(SeO3)2Cl2, an insulating spin gap system

Novel copper cadmium selenite chloride has been synthesized via vapor transport reaction as well as by solid state process. CdCu2(SeO3)2Cl2 crystallizes in a monoclinic space group I2/a with cell constants a ​= ​7.8057(3) Å, b ​= ​9.6036(4) Å, c ​= ​10.7817(5) Å and β ​= ​102.362(4)°, Z ​= ​4. Its crystal structure can be described as an open channel three-dimensional framework, formed by [CdO2Cl4] and [CuO4Cl2] polyhedra interconnected by pyramidal SeO3 groups. The copper polyhedra form magnetically isolated dimers with a spin gap Δ ​= ​38.7 ​± ​0.8 ​meV, as defined from magnetic susceptibility measurements. The electron band gap estimated by diffuse reflectance method Eg ​= ​2.82 ​± ​0.02 ​eV is in agreement with the yellow-green color of the substance. Density functional theory provides the values of electron (2.4 ​eV) and spin (36.6 ​meV) gaps consistent with experimental observations.

Comparative analysis of anti-reflection coatings on solar PV cells through TiO2 and SiO2 nanoparticles

PurposePhoton absorbance and reflectance are the most important parameters for the recombination of electron-hole pairs. Bandgap energy plays a vital role in photon absorption. That is, the photons with energy greater than band gap energy are absorbed. Also, the refractive index of semiconductors is responsible for photon reflection, as the surface with the highest refractive index will reflect more photons than a surface with have a low refractive index. The purpose of this paper is to improvise the absorbance and reduce the reflectance of photons on the front surface of solar cells.Design/methodology/approachPhoton reflection is results in reduction in electron-hole pair generation due to the high refractive index of semiconductive materials. To overcome this problem, an Anti-reflection (AR) coating of TiO2 and SiO2 is undertaken on solar cells through the Sol-spin coating method. Finally, the effectiveness of the Anti-Reflection coating is scrutinized through UV Vis-Spectroscopy, which provides details regarding reflectance, absorbance and bandgap energy characteristics.FindingsUV–visible spectroscopy was used to measure the responses from the samples. The samples responded to the ultraviolet and visible range of electromagnetic radiation perfectly. UV spectroscopy was done before and after the antireflection coating of TiO2 and SiO2 over the solar cell to find their corresponding extreme reflectance and absorbance values. The effects of TiO2 and SiO2 were evaluated from the results.Originality/valueIn this research work, the authors have done anti-reflection coating over solar cells with nanoparticles derived from sol-gel process. Absorbance of photons observed through diffuse reflection method.

Diffusion Reflection Method for Early Detection of Oral Squamous Cell Carcinoma Specifically Targeted by Circulating Gold-Nanorods Bio-Conjugated to Anti-Epidermal Growth Factor Receptor.

BackgroundTranslation of nanomedical developments into clinical application is receiving an increasing interest. However, its use for oral squamous cell carcinoma (OSCC) diagnosis remains limited. We present an advanced nanophotonic method for oral cancer detection, based on diffusion reflection (DR) measurements of gold-nanorods bio-conjugated to anti-epidermal growth factor receptor (C-GNRs) specifically attached to OSCC cells.ObjectiveTo investigate in a rat model of oral carcinogenesis the targeting potential of C-GNRs to OSCC by using the DR optical method.Materials and MethodsOSCC was induced by the carcinogen 4-nitroquinoline-N-oxide (4NQO). C-GNRs were introduced locally and systemically and DR measurements were recorded from the surface of the rat tongue following illumination with red laser beam. Rats were divided into experimental and control groups. The results were compared with the histologic diagnosis.ResultsA total of 75 Wistar-derived rats were enrolled in the study. Local application did not reveal any statistical results. DR measurements following intravenous injection of C-GNRs revealed a significant increase in light absorption in rats with OSCC compare with rats without cancer (p<0.02, sensitivity 100%, specificity 89%). In addition, absorption of light increased significantly in cases of severe dysplasia and cancer (high risk) compared to rats without cancer and rats with mild dysplasia (low risk) (86% sensitivity and 89% specificity, AUC=0.79).ConclusionCombining nanotechnology and nanophotonics for in vivo diagnosis of OSCC serves as additional tier in the translation of advanced nanomedical developments into clinical applications. The presented method shows a promising potential of nanophotonics for oral cancer identification, and provides support for the use of C-GNRs as a selective drug delivery.

Extraction of optical properties from a turbid medium using fiber probe for spectral and spatial diffuse reflectance measurement

Diffuse reflectance technique is popular in the study of tissue physiology through the change in optical properties in a noninvasive manner. Diffuse reflected light intensity is commonly collected either from a single distance with spectral measurement or from a single wavelength with different spatial distances. Improving existing systems is necessary in order to obtain information from greater depths and in smaller volumes. In this paper, we propose a fast and compact fiber probe-based diffuse reflectance method for combining the spectral measurements in the range of 400–950 nm and spatial information up to 1.33 mm from the illumination source. First, we chose the most appropriate analysis model for the proposed distances between the fiber probe and tested it on solid phantoms with varying scattering and absorption components. The measurements are compared to the scattering coefficients according to Mie theory and the absorption according to spectrophotometer measurements. Next, we measured two-layer phantoms with constant scattering and absorption contrast in different layer thicknesses. We extracted the penetration depth from the measured effective absorption coefficient. In the near-IR, we were able to detect the absorption coefficient of the bottom phantom layer behind a top layer of up to 5 mm. We achieved a maximum penetration depth of 5.7 mm for 5 mm top layer thickness at 900 nm. Our fiber probe diffuse reflectance system can be used in the near future for skin lesion detection in clinical studies.

FTIR spectral signatures of amazon inorganic phosphates: Igneous, weathering, and biogenetic origin

The characterization of phosphates is generally hampered by the variability of their sources, the complexity of the mineralogical assemblies and/or the thermochemical transformations undergone. Fourier transform infrared (FTIR) spectroscopy can characterize and differentiate phosphates in a practical and efficient way. In this sense, in order to differentiate phosphates from different Amazonian deposits and establish a spectral database, initially small because it is starting, six samples of phosphate rocks were analyzed by FTIR spectroscopy in the near-IR and middle-IR regions using the transmittance, attenuated reflectance, and diffuse reflectance methods. X-ray diffraction and X-ray fluorescence spectroscopy were also used as complementary analyses. The IR results revealed that the transmittance and diffuse reflectance methods are the most suitable for the analysis of phosphate materials, and they should be used together whenever possible. The identification of the PO4 bands, as well as of the (CO3)2-, Al2OH, and NH4 bands, allowed the differentiation of the phosphate materials according to their geological source and the establishment of a database of the studied materials by both the transmittance and diffuse reflectance methods.

Influence of PDA Coating on the Structural, Optical and Surface Properties of ZnO Nanostructures.

Polydopamine (PDA) is a new biocompatible material, which has prospects in biomedical and sensor applications. Due to functional groups, it can host wide range of biomolecules. ZnO nanostructures are well known templates for optical sensors and biosensors. The combination of ZnO and PDA results in a change of optical properties of ZnO–PDA composites as a shift of photoluminescence (PL) peaks and PL quenching. However, to date, the effect of the PDA layer on fundamental properties of ZnO–PDA nanostructures has not been studied. The presented paper reports on optical and surface properties of novel ZnO–PDA nanocomposites. PDA layers were chemically synthesized on ZnO nanostructures from different solution concentrations of 0.3, 0.4, 0.5 and 0.7 mg/mL. Structure, electronic and optical properties were studied by SEM, Raman, FTIR, diffuse reflectance and photoluminescence methods. The Z-potential of the samples was evaluated in neutral pH (pH = 7.2). The response of the samples towards poly-l-lysine adsorption, as a model molecule, was studied by PL spectroscopy to evaluate the correlation between optical and surface properties. The role of the PDA concentration on fundamental properties was discussed.

High-performance hydrogen evolution of NiB/ZnCdS under visible light irradiation

With the continuous growth of global energy demand, the artificial photosynthetic system of photocatalytic decomposition of hydrogen production has been widely concerned, CdZnS, a photocatalyst based on solid solution, has shown good performance. In order to avoid the rapid recombination of photogenerated electron and hole, metal boride is added as a catalyst to enhance its photocatalytic hydrogen production performance. We prepared CdZnS photocatalyst by hydrothermal method, and synthesized different proportions of NiB/CdZnS catalyst by programmed heating method and calcined it at 773K. Characterized by XRD, XPS, uv–vis diffuse reflection and other methods, CZS solid solution and NiB/CdZnS were synthesized, and the absorption edge of NiB/CZS was redshifted relative to the pure CdZnS. The addition of NiB can effectively inhibit the recombination of electrons and holes to improve the separation efficiency of photogenerated charge, and its content has an impact on photocatalytic activity. We found that under visible light irradiation, when the content is 15 wt%, the hydrogen production was the highest. The optimal quantum efficiency was 13.3%, and the hydrogen production reacheed 8137 μmol/g/h, which is 17 times that of pure CdZnS. The addition of NiB greatly improved the photocatalytic performance of CdZnS.

Fabrication of Ag based ternary nanocomposite system for visible-light photocatalytic hydrogen evolution reaction

Solar driven visible photocatalytic H2 evolution using semiconductors is recognized as one of the most promising routes for clean energy technology; however, efficient visible light utilization and charge separation are the key roles in a photocatalyst system for high activity. Herein, Ag based ternary nanocomposite system, Ag2S/Ag/Ag3VO4 was synthesized by chemical reduction and subsequent hydrothermal methods. The prepared nanocomposites were characterized by Powder X-ray diffraction, X-ray photoelectron spectroscopy, Scanning and transmission electron microscopy, UV–vis diffuse reflectance and photoluminescence spectroscopy methods. The Ag2S/Ag/Ag3VO4 ternary nanocomposite system displayed a higher photocatalytic H2 evolution activity than that of pure Ag3VO4, Ag2S and their binary composites under visible light irradiation. In the present work, Ag2S/Ag/Ag3VO4 exhibited a photocatalytic H2 evolution activity of ~8.5 mmol·g−1. The enhanced photocatalytic activity can be attributed to the improved visible light absorption and effective charge separation between Ag3VO4 and Ag2S via the electron shuttle mediator Ag.

Diffuse Reflectance of Powders

The propagation of light through powders differs significantly from the propagation of light in a homogeneous material, since the light scatters off points in its path. Colors of powders are related to the fineness of the powder, when the powder is illuminated with white light. As Fourier transform infrared has become more common, the diffuse reflection method has become widely used. Diffuse reflectance is an excellent sampling tool for powdered materials.

Hyperlipidemic mice as a model for a real‐time in vivo detection of atherosclerosis by gold nanorods‐based diffusion reflection technique

Atherosclerosis (AS), the leading cause of morbidity and mortality in cardiovascular disease, needs an early detection for treatment and prevention of fatal events. Here, for the first time, we applied gold nanorods (GNRs)-assisted diffusion reflection (DR), a noninvasive technique for in vivo detection of AS in a high-fat-diet-induced c57bl mouse model, which resembles the manifestation of AS in humans. DR simply detects the change in light reflection profile of tissue due to the accumulation of GNRs in the AS plaques and enables clear detection of AS lesions in carotid and femoral arteries of these hyperlipidemic mice. After 24 hours post-GNRs injection, DR showed the highest efficiency of AS detection. Moreover, the sensitivity of the DR method is much higher than computed tomography (CT) and is comparable to ex vivo high-resolution CT. Our results strongly suggest that the DR method can detect early atherosclerotic lesions in a sensitive and specific manner.

The peculiarities of light absorption and light emission in Cu-doped Y-stabilized ZrO2 nanopowders

The influence of doping with copper and annealing temperature on the characteristics of yttrium-stabilized ZrO2 nanopowders was investigated using photo- and cathodoluminescence as well as diffuse reflectance and electron paramagnetic resonance methods. After annealing at temperatures below 800 °С, both Cu-doped and Cu-free powders demonstrate light emission in the blue–red spectral range that are characteristic of the tetragonal ZrO2 phase. In the excitation spectra of blue–orange photoluminescence it was found a maximum in the range of light absorption by oxygen vacancies, indicating that the corresponding emitting centers are vacancy related complexes. A red luminescence band was found to be excited only by the light from band-to-band ZrO2 absorption. It was observed that the increase of annealing temperature up to 1000 °C stimulates the appearance of additional luminescence bands at ~ 510 and 580 nm correlated with the formation of monoclinic ZrO2 phase. The corresponding emitting center is considered to be a substitutional copper ion, the excitation of which can occur both via the capture of free carriers and via the energy transfer from oxygen vacancies.

Three-Dimensional Highly Sensitive Diffusion Reflection-Based Imaging Method for the in Vivo Localization of Atherosclerosis Plaques Following Gold Nanorods Accumulation.

In this work, we present a novel, simple, and highly accurate three-dimensional (3D) diffusion reflection (DR) imaging system and method for the detection of accumulation sites of gold nanorods (GNRs) within the tissue. GNRs are intensively used for diagnosis purposes of varied diseases, mainly because of their ability to well absorb visible light, which introduces them as terrific contrast agents in various imaging and theranostics methods. Lately, these GNRs unique absorption properties have served in DR intensity-based measurements, suggesting a novel diagnostic tool, DR-GNRs. In this paper, we show a new measurement system and method for DR, based on its radial collection from the tissue. These radial measurements enabled a unique 3D presentation of the DR-GNR, introducing the dimensions ρ for the radius, θ for the angle, and Γ for the reflected intensity. On the basis of the diffusion model, which enables to correlate between the sample’s optical properties and its reflectance, a unique, radial map is presented. This map introduces the slopes of the DR curves in each measured angle, which are linearly correlated with the tissue’s optical properties and with the GNRs concentrations within the tissue, thus enables the exact radial localization of the GNRs in the sample. We show the detection of macrophage accumulation in tissue-like phantoms, as well as the localization of unstable plaques in hyperlipidemic mice, in vivo. This highly accurate, powerful technology paves the way toward a real-time detection method that can be successfully integrated in the rapid increasing field of personalized medicine.