1. Articles from Raju Poddar

    1-20 of 20
    1. Ex-vivo molecular imaging with Upconversion Nanoparticles (UCNPs) using Photo Thermal Optical Coherence Tomography (PTOCT)

      Ex-vivo molecular imaging with Upconversion Nanoparticles (UCNPs) using Photo Thermal Optical Coherence Tomography (PTOCT)

      We demonstrate the photothermal optical coherence tomography (PTOCT) system, with upconversion nanoparticles (UCNPs) as a molecular probe. We synthesize hydrophilic, biocompatible upconversion nanoparticles (UCNPs) using hydrothermal synthesis. We developed the PTOCT system along with the signal processing tool and applied this technique on animal tissue phantom for targeted imaging. The ‘lock-in detection’ of the amplitude modulated photothermal beam (980 nm), which used to excite the UCNPs was the backbone of the signal processing algorithm. The signal processing was further established in different aspects. As an application part, the diffusion dynamics of the UCNPs was performed inside the tissue to study ...

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    2. Real-time assessment and characterization of immobilized lipase onto a natural matrix and qualitative reaction kinetic studies using swept-source optical coherence tomography

      Real-time assessment and characterization of immobilized lipase onto a natural matrix and qualitative reaction kinetic studies using swept-source optical coherence tomography

      The current study presents a method based on Optical Coherence Tomography (OCT) for non-destructive, real-time analysis and portrayal of immobilization efficacy for lipase on a natural matrix namely, eggshell. Subsequently, qualitative biochemical reaction kinetics of immobilized lipase was also studied. Successful immobilization of lipase on eggshell was confirmed by the presence of a clear peak in ‘A’ scan of OCT image. From immobilization kinetics it is clearly observed that the thickness of the highest peak of the A-scan increases significantly and peak intensity saturated after 90 min of incubation. Hydrolysis of oil using immobilized lipase indicated that the release of ...

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      Mentions: Raju Poddar
    3. Synthesis of NaGdF4:Er3+/Yb3+ Upconversion Particles as Exogenous Contrast Agent for Swept-Source Optical Coherence Tomography: In vitro Animal Tissue Imaging

      Synthesis of NaGdF4:Er3+/Yb3+ Upconversion Particles as Exogenous Contrast Agent for Swept-Source Optical Coherence Tomography: In vitro Animal Tissue Imaging

      Swept-source optical coherence tomography (SSOCT) is a non-contact, non-invasive bioimaging tool that usesvarious probes to get high contrast images. Rare-earth based upconversion particles (UCPs) providea uniqueplatform to enhance the capabilities of bioimaging techniques. The UCPs can act as contrast enhancers for SSOCT with additional optical functionality and hence in this work upconversion emission optimized PVP/NaGdF4:Er3+/Yb3+UCPs were synthesized and then injected to chicken breast tissues to enhance the SSOCT images. As synthesized samples have shown good biocompatibility towards HEK293, HeLa cell lines and showed apparent enhancement in contrast to SSOCT images. Additionally, compared to the bare NaGdF4 ...

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      Mentions: Raju Poddar
    4. In-vivo analysis of iron-gold composite nanoparticles as potential exogenous contrast agents for Magnetomotive Optical Coherence Tomography (MMOCT)

      In-vivo analysis of iron-gold composite nanoparticles as potential exogenous contrast agents for Magnetomotive Optical Coherence Tomography (MMOCT)

      Magnetomotive optical coherence tomography (MMOCT) is a functional modification of conventional optical coherence tomography (OCT). It utilizes the nano-scale displacement embedded magnetic nanoparticles (MNPs) and subsequent amplitude and phase changes in OCT interferogram scattered from samples. We report a new robust method for ‘phase-lock-in’ detection of MMOCT signals and subsequent imaging. We validated this method utilizing iron-gold (Fe-Au) composite nanoparticles as an exogenous contrast agent for MMOCT. High contrast and specific background-subtracted images was generated for Fe-Au MNPs targeted samples. MMOCT with MNPs imaging systems was corroborated with tissue phantoms and in-vivo swiss albino mice model with modulating external magnetic ...

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    5. In Vitro Imaging of Animal Tissue with Upconversion Nanoparticles (UCNPs) as a Molecular Probing Agent Using Swept Source Optical Coherence Tomography (SSOCT)

      In Vitro Imaging of Animal Tissue with Upconversion Nanoparticles (UCNPs) as a Molecular Probing Agent Using Swept Source Optical Coherence Tomography (SSOCT)

      Purpose The aim of the current study is to demonstrate the potential of rare earth (RE) based upconversion nanoparticles (UCNPs) as molecular probing agents for non-invasive depth-resolved bioimaging technique, swept-source optical coherence tomography (SSOCT). Methods The Na + doped La 2 O 3 :Er 3+ /Yb 3+ UCNPs were synthesized using a solution combustion route with characterization for emission spectra and morphological study. A custom made SSOCT system was also incorporated for tissue imaging with an A-scan rate of 100 kHz/s, the central wavelength of 1060 nm, an axial and lateral resolution of ~ 4.5 µm and ~ 13 µm in ...

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      Mentions: Raju Poddar
    6. Efficacy of Spectroscopic Optical Coherence Tomography (sOCT) for instantaneous study of nitrilase enzyme kinetics

      Efficacy of Spectroscopic Optical Coherence Tomography (sOCT) for instantaneous study of nitrilase enzyme kinetics

      We present monitoring of nitrilase enzyme assay in real-time by means of Spectroscopic Optical Coherence Tomography (sOCT). Combination of principal component analysis (PCA) algorithm with Swept Source Optical Coherence Tomography (SSOCT), to extract the absorption spectra of the sample, termed as sOCT. Spectroscopic information of nitrilase enzyme obtained from sOCT is used to investigate dynamic enzyme kinetic reactions. Different principle components give complete information regarding the composition of the samples. Further, Fourier Transform Infrared Spectroscopy (FTIR) analysis has been also performed to validate the PCA absorption spectra. Samples were prepared in controlled condition and evaluated at a regular time interval ...

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    7. Characterization and oxygen saturation study of human retinal blood vessels evaluated by spectroscopic Optical Coherence Tomography Angiography

      Characterization and oxygen saturation study of human retinal blood vessels evaluated by spectroscopic Optical Coherence Tomography Angiography

      Optical coherence tomography is non-invasive diagnostic technique for performing high resolution (~µm) cross sectional imaging. In this article, we demonstrate characterization and oxygen saturation studies of human retinal blood vessels with Principal Component Analysis (PCA) based Spectroscopic Optical Coherence Tomography-based Angiography. A Fourier Domain Mode-Locked laser having an axial imaging resolution of ~7.5 µm, with an A-scan sweep rate of 1.7 MHz and centre wavelength of 1060 nm, was utilized as an OCT source. PCA has been used in conjunction with a scanning Short Time Fourier Transform, procedure to isolate the probable amount of oxygenated and deoxygenated haemoglobin ...

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    8. Towards characterization of bacterial colonies and biofilms: an approach based on swept source optical coherence tomography

      Towards characterization of bacterial colonies and biofilms: an approach based on swept source optical coherence tomography

      The continuous development of microorganism colonies may lead to the development of biofilms. The ability to observe bacterial layers in real time using Optical Coherence Tomography (OCT) can be beneficial for cross-sectional growth studies of bacterial biofilms. A new mathematical model has been developed and utilized to calculate the backscattering optical properties of sample and estimate the necessary parameters. The spectroscopic based analytical method has been successfully demonstrated for characterization of different bacterial colonies and biofilms. The results were verified with conventional ‘Gram staining’ method. The proposed analytical method has potential to monitor realtime growth kinetics of bacteria. The quantities ...

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      Mentions: Raju Poddar
    9. Investigation of Puccinia triticina contagion on wheat leaves using swept source optical coherence tomography

      Investigation of Puccinia triticina contagion on wheat leaves using swept source optical coherence tomography

      We present an investigation on applicability of swept-source optical coherence tomography (SSOCT) to examine the internal structures of plant leaves. This study helps to identify the growth and spread of the leaf rust disease in leaves of wheat plants, caused by Puccinia triticina . The epidermal cell layer and parenchyma cell layer of the acquired OCT images are correlated with the histological images to show distinctive leaf morphological boundaries. In the OCT images, the thickness of the parenchyma cell layer in healthy and infected samples are compared and analyzed. Accurate morphological and quantitative information are obtained with our developed system for ...

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      Mentions: Raju Poddar
    10. Zinc oxide nanoparticles (ZnONPs) as contrast agent for imaging of animal tissue using swept source optical coherence tomography (SSOCT)

      Zinc oxide nanoparticles (ZnONPs) as contrast agent for imaging of animal tissue using swept source optical coherence tomography (SSOCT)

      We present applicability of ZnO nanoparticles (ZnONPs) as a potential contrast agent for Optical Coherence Tomography (OCT) imaging. A 1064 nm laser source was used in a swept source configuration capable of a scanning rate of 100 kHz (100,000 A-lines/s). Swept Source Optical Coherence Tomography (SSOCT) is a variation of OCT, offering greater scan rates, higher resolution and signal-to-noise ratios. To enhance the contrast of an OCT frame, ZnO nanoparticles were used as an exogeneous contrast agent, which were fabricated using zinc acetic acid derivation and oxalic acid via precipitation. The particles were characterized using UV–vis Spectroscopy ...

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      Mentions: Raju Poddar
    11. Imaging of human finger nail-fold with MHz A-scan rate swept source optical coherence tomography

      Imaging of human finger nail-fold with MHz A-scan rate swept source optical coherence tomography

      We present a non-invasive three-dimensional depth-resolved micro-structure and micro-vasculature imaging of a human fingernail-fold with a swept-source optical coherence tomography (ssOCT) system at a 1064 nm center wavelength. A phase variance OCT angiography (OCTA) method was implemented for motion contrast OCT imaging. A Fourier-domain mode-locked light source with an A-scan rate of 1.7 MHz (1 700 000 A-scans s −1 ) was utilized for imaging. The experimental setup demonstrates OCT and OCTA imaging with an area of ~5 mm   ×   5 mm (within the Nyquist limit). Details of the ssOCTA system such as system parameters, scanning protocols, acquisition time, challenges, and ...

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      Mentions: Raju Poddar
    12. TiO2 nanoparticles as exogenous contrast agent for 1 µm swept source optical coherence tomography: an in vitro study

      TiO2 nanoparticles as exogenous contrast agent for 1 µm swept source optical coherence tomography: an in vitro study

      Optical coherence tomography (OCT) is a rapidly evolving, robust technology that has profoundly changed the practice of medical imaging. Swept source OCT (SSOCT) combines the standard time domain and the spatially encoded frequency domain OCT. We have employed a high-speed SSOCT system that utilizes a swept source laser with an A-scan rate of 100 kHz and a central wavelength of 1060 nm for the imaging of the tissue. SSOCT at 1060 nm allows for high penetration in the tissue. TiO 2 nanoparticles (NPs) are mostly used for various experimental purposes as an exogenous imaging contrast agent. The in vitro imaging ...

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      Mentions: Raju Poddar
    13. Silver nanoparticles (AgNPs) as a contrast agent for imaging of animal tissue using swept-source optical coherence tomography (SSOCT)

      Silver nanoparticles (AgNPs) as a contrast agent for imaging of animal tissue using swept-source optical coherence tomography (SSOCT)

      We present noninvasive three-dimensional depth-resolved imaging of animal tissue with a swept-source optical coherence tomography system at 1064 nm center wavelength and silver nanoparticles (AgNPs) as a potential contrast agent. A swept-source laser light source is used to enable an imaging rate of 100 kHz (100 000 A-scans s −1 ). Swept-source optical coherence tomography is a new variant of the optical coherence tomography (OCT) technique, offering unique advantages in terms of sensitivity, reduction of motion artifacts, etc. To enhance the contrast of an OCT image, AgNPs are utilized as an exogeneous contrast agent. AgNPs are synthesized using a modified Tollens ...

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      Mentions: Raju Poddar
    14. Challenges and advantages in wide-field optical coherence tomography angiography imaging of the human retinal and choroidal vasculature at 1.7-MHz A-scan rate

      Challenges and advantages in wide-field optical coherence tomography angiography imaging of the human retinal and choroidal vasculature at 1.7-MHz A-scan rate

      We present noninvasive, three-dimensional, depth-resolved imaging of human retinal and choroidal blood circulation with a swept-source optical coherence tomography (OCT) system at 1065-nm center wavelength. Motion contrast OCT imaging was performed with the phase-variance OCT angiography method. A Fourier-domain mode-locked light source was used to enable an imaging rate of 1.7 MHz. We experimentally demonstrate the challenges and advantages of wide-field OCT angiography (OCTA). In the discussion, we consider acquisition time, scanning area, scanning density, and their influence on visualization of selected features of the retinal and choroidal vascular networks. The OCTA imaging was performed with a field of ...

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    15. Implementation of the swept source optical coherence tomography (SSOCT) system with a statistical method to analyze optical properties of turbid media

      Implementation of the swept source optical coherence tomography (SSOCT) system with a statistical method to analyze optical properties of turbid media

      We present a spectroscopic OCT (sOCT) system to extract spectroscopic properties of turbid media using principle component analysis (PCA) and swept source optical coherence tomography (SSOCT). Extracted results are well comparable with the standard photo spectrometer technique. This system has potential for real time measurement of blood oxygen saturation and monitoring of relative concentration for other metabolic compounds inside human body.

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      Mentions: Raju Poddar
    16. In vivo volumetric depth-resolved vasculature imaging of human limbus and sclera with 1μm swept source phase-variance optical coherence angiography

      In vivo volumetric depth-resolved vasculature imaging of human limbus and sclera with 1μm swept source phase-variance optical coherence angiography

      We present in vivo volumetric depth-resolved vasculature images of the anterior segment of the human eye acquired with phase-variance based motion contrast using a high-speed (100 kHz, 10 5 A-scans/s) swept source optical coherence tomography system (SSOCT). High phase stability SSOCT imaging was achieved by using a computationally efficient phase stabilization approach. The human corneo–scleral junction and sclera were imaged with swept source phase-variance optical coherence angiography and compared with slit lamp images from the same eyes of normal subjects. Different features of the rich vascular system in the conjunctiva and episclera were visualized and described. This system ...

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    17. In vivo imaging of human vasculature in the chorioretinal complex using phase-variance contrast method with phase-stabilized 1-μm swept-source optical coherence tomography

      In vivo imaging of human vasculature in the chorioretinal complex using phase-variance contrast method with phase-stabilized 1-μm swept-source optical coherence tomography

      We present a noninvasive phase-variance (pv)–based motion contrast method for depth-resolved imaging of the human chorioretinal complex microcirculation with a newly developed phase-stabilized high speed (100-kHz A-scans/s) 1 - μ m swept-source optical coherence tomography (SSOCT) system. Compared to our previous spectral-domain (spectrometer based) pv-spectral domain OCT (SDOCT) system, this system has the advantages of higher sensitivity, reduced fringe wash-out for high blood flow speeds and deeper penetration in choroid. High phase stability SSOCT imaging was achieved by using a computationally efficient phase stabilization approach. This process does not require additional calibration hardware and complex numerical procedures. Our phase stabilization ...

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    18. In vitro 3D anterior segment imaging in lamb eye with extended depth range swept source optical coherence tomography

      In vitro 3D anterior segment imaging in lamb eye with extended depth range swept source optical coherence tomography

      A complex conjugate resolved, extended depth range, high speed 1 μm swept-source optical coherence tomography (SSOCT) provides a dense three-dimensional (3-D) imaging of the entire anterior segment of eye. SSOCT system utilizes “coherence revival” characteristics of the light source (external cavity tunable laser, ECTL), which is automatically phase modulated. We describe implementation of this with a common swept laser with built-in k-clock to allow imaging in high depth range, 10.5 mm in air, without any external MZI clock. The system is capable of generating long depth range without any modulators or frequency shifter. Most of the commercially available OCT ...

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      Mentions: Raju Poddar
    19. Improved in vivo imaging of human blood circulation in the chorioretinal complex using phase variance method with new phase stabilized 1 μm swept-source optical coherence tomography (pv-SSOCT)

      Improved in vivo imaging of human blood circulation in the chorioretinal complex using phase variance method with new phase stabilized 1 μm swept-source optical coherence tomography (pv-SSOCT)

      We demonstrate the feasibility of our newly developed phase stabilized high-speed (100 kHz A-scans/s) 1 μm sweptsource optical coherence tomography (SSOCT) system with the phase-variance based motion contrast method for visualization of human chorioretinal complex microcirculation. Compared to our previously reported spectral domain (spectrometer based) phase-variance (pv)-SDOCT system it has advantages of higher sensitivity, reduced fringe washout for high blood flow speeds and deeper penetration in choroid. High phase stability SSOCT imaging was achieved by using a computationally efficient phase stabilization approach. This process does not require additional calibration hardware and complex numerical procedures. Our phase stabilization method ...

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    20. Application of full range swept source optical coherence tomography for imaging of the anterior eye segment in patients with type I Boston Keratoprosthesis

      Application of full range swept source optical coherence tomography for imaging of the anterior eye segment in patients with type I Boston Keratoprosthesis

      We present a high-speed complex conjugate resolved 1 μm swept source optical coherence tomography [SS-OCT] system using coherence revival of the light source for clinical imaging of the anterior segment of the eye. High-speed of 100,000 A-scans/sec and 1 μm imaging window of OCT permits dense 3D imaging of the anterior segment, minimizing the influence of motion artifacts and deep penetration of images for topographic analysis. The swept laser performance with internal clocking was adapted to achieve extended imaging depth requirements. The feasibility of our instrument for visualization of the anterior segment of patients with the Boston Keratoprosthesis ...

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    1-20 of 20
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    Application of full range swept source optical coherence tomography for imaging of the anterior eye segment in patients with type I Boston Keratoprosthesis Improved in vivo imaging of human blood circulation in the chorioretinal complex using phase variance method with new phase stabilized 1 μm swept-source optical coherence tomography (pv-SSOCT) In vitro 3D anterior segment imaging in lamb eye with extended depth range swept source optical coherence tomography In vivo imaging of human vasculature in the chorioretinal complex using phase-variance contrast method with phase-stabilized 1-μm swept-source optical coherence tomography In vivo volumetric depth-resolved vasculature imaging of human limbus and sclera with 1μm swept source phase-variance optical coherence angiography Implementation of the swept source optical coherence tomography (SSOCT) system with a statistical method to analyze optical properties of turbid media Challenges and advantages in wide-field optical coherence tomography angiography imaging of the human retinal and choroidal vasculature at 1.7-MHz A-scan rate Silver nanoparticles (AgNPs) as a contrast agent for imaging of animal tissue using swept-source optical coherence tomography (SSOCT) TiO2 nanoparticles as exogenous contrast agent for 1 µm swept source optical coherence tomography: an in vitro study Investigation of Puccinia triticina contagion on wheat leaves using swept source optical coherence tomography Clinical Usefulness of a Novel Optical Coherence Tomography Procedure, “Low Molecular Weight Dextran Infusion Followed by Catheter PUSH (D-PUSH)” Optical Coherence Tomography to Guide Percutaneous Coronary Intervention of the Left Main Coronary Artery: the LEMON study