Faculty of Science

Permanent URI for this communityhttps://hdl.handle.net/10155/386

The Faculty of Science (FSCI) provides students with the tools needed to adapt to future developments in the scientific path of their choice. Areas of study include applied & industrial mathematics, chemistry, integrative neuroscience, forensic science, computer science and physics.

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Browsing Faculty of Science by Author "Agarwal, Nisha Rani"

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    Detection of trace concentrations of small and big molecules through vibrational spectroscopy
    (2024-08-01) Balasubramanian, Janani; Agarwal, Nisha Rani
    In this thesis, we aim to detect analytes of varying sizes using surface-enhanced Raman spectroscopy (SERS) without the need for customizing the morphology of nanostructured substrate. Signal enhancement in SERS occurs near plasmonic nanoparticles within "hotspots" (<10 nm), which limits detection to molecules that can access these regions. We investigated two differently fabricated SERS-active substrates: pulsed laser deposited gold nanoparticles and electrochemically deposited silver nanoparticles, optimized for 633 nm and 532 nm Raman lasers, respectively. Characterization was performed using UV-Visible spectroscopy, scanning electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. We analyzed zeatin, a small plant hormone (219 Da), and hemoglobin (Hb), a large protein (64,500 Da). Zeatin detection ranged from 1 mM to 1 nM, even in complex bacterial media, while Hb detection involved ligand-functionalized substrates targeting the heme group for specific oriented immobilization, detecting down to 10 nM. This study demonstrates the potential of SERS for sensitive and selective detection of diverse analytes, paving the way for advanced biosensing applications.
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    Performance assessment of Au SERS substrates prepared by deposition of Au nanoparticles on screen-printed SiO2 particle films
    (2023-02-01) Simpson, Raquel E.; Trevani, Liliana; Agarwal, Nisha Rani
    Surface-enhanced Raman spectroscopy (SERS) is a highly studied technique for simple and rapid trace analysis. Screen-printing, a low-cost fabrication method, has been proposed as a reproducible and affordable approach for the preparation of 3D SERS-active substrates. In this work, a new solution-based film fabrication method is proposed for the preparation of Au@SiO2 3D SERS-active substrates. The procedure involved the synthesis of SiO2 nanoparticles for the deposition of thin porous SiO2 films on silica slides using a screen-printing approach. Annealed SiO2 particle films were subsequently functionalized to promote the adsorption of Au nanoparticles in the SiO2 matrix. Materials and films were characterized using several methods. The effects of particle properties and paste formulation on the analytical SERS performance of the film were studied using Rhodamine 6G as the target analyte; even though it is difficult to compare between studies, due to the lack of well-established standardization protocols.