Development of novel plasmonic nanoparticles and fluorescent probes towards respective antibacterial and sensor studies.

Autor: TURIBIUS SIMON, 史拓立
Rok vydání: 2017
Druh dokumentu: 學位論文 ; thesis
Popis: 105
The prime objective of this thesis is to design and synthesis of short self-assembled peptide-based hydrogels mineralized with silver nanoparticles, fluorescent chemosensor probes and dual functionalized gold nanoparticles towards antibacterial studies, metal ions and clenbuterol detections, respectively. The Chapter 1 describes the significance of silver nanoparticle entrapped short peptide in antibacterial applications. Then, highlighted significance of designed fluorescent chemosensors and functionalized gold nanoparticles and mechanism of signal transduction of several probes in metal ions and clenbuterol detections. In chapter 2, we have focused on a biocompatible N-terminally 2-(Naphthalen-6-yl) acetic acid (Nap) protected Phe-Phe-Cys peptide (Nap-FFC) synthesized by liquid phase method. This Nap-FFC peptide was used to design supramolecular hydrogel via self-assembling process. In addition, the mineralized silver based Nap-FFC nanocomposites (AgNPs@Nap-FFC) has been prepared by utilizing sodium borohydride, where Nap-FFC acts as scaffolds for the mineralization of silver nanoparticles (AgNPs) as well as plays the key role of stabilizing agents for the synthesized AgNPs. As prepared, AgNPs@Nap-FFC nanocomposites have a high monodispersity, long term stability, and functional flexibility in comparison to other AgNPs based nanocomposites. More interestingly, AgNPs@Nap-FFC has exhibited antibacterial effect against both Gram-positive (Methicillin-resistant Staphylococcus aureus), Gram-negative (Acinetobacter baumannii) bacteria and showed favorable biocompatibility to HeLa cells. Hence, this study implies that AgNPs@Nap-FFC based nanocomposites prepared by simple and cost-effective manner, will be more effective to be used in future antibacterial wound dressing and biomedical application without side effects. Chapter 3 discusses about a simple pyrene based schiff base derivative 2-((pyren-1-ylmethylene) amino) ethanol (PE) has been synthesized via one-pot reaction and its nano-aggregation induced emission (AIEE) characteristics were reported through UV/PL and supported by TEM and DLS studies. Interestingly, PE in CH3CN revealed the naked eye and fluorescence turn-on sensing responses towards Fe3+, Cr3+ and Al3+ ions, via PET and PE-PE* excimer formation. The 2:1 stoichiometry of sensor complexes PE ---M3+ (M = Fe/ Cr/ Al) were calculated from job’s plots based on UV-Vis absorption titrations and supported by FTIR and ESI (+Ve) mass analysis. In addition, the binding sites of sensor complex PE ---M3+ were well established from the 1H NMR titrations. Furthermore, the fluorescence reversibility of PE ---M3+ complexes, via consequent additions of M3+ ions and PMDTA, respectively. The detection limits (LODs) and the association constants (Kas) values of PE ---M3+ complexes were calculated by standard deviation and linear fittings. Furthermore, the quantum yield (Φf), TEM analysis, pH effect and density functional theory (DFT) studies were investigated for the PE ---M3+ sensor complexes. More importantly, confocal fluorescence microscopy imaging in Raw264.7 cells showed that PE could be used as an effective fluorescent probe for detecting Fe3+, Cr3+ and Al3+ ions in living cells. In Chapter 4, we have demonstrated a novel anthracene and pyridine comprising schiff base derivative 2-(2-(anthracen-9-ylmethylene)hydrazinyl)pyridine (AP) has been synthesized via one-pot reaction and its fluorescent “OFF-ON” detection of Cu2+ ions, via PET based mechanism was reported firstly. The 1:1 stoichiometry of AP ---Cu2+ sensor complex was calculated from job’s plot based on PL titrations and supported by ESI (+Ve) mass analysis. In addition, the binding sites of sensor conjugate AP ---Cu2+ was buttressed by the 1H NMR titration. The detection limit (LOD) and association constant (Ka) of AP ---Cu2+ complex was scrutinized by standard deviation and linear fittings. Furthermore, quantum yield (Φf), SEM analysis, pH effect, FTIR interpretation and density functional theory (DFT) studies were investigated for the AP ---Cu2+ sensing conjugate. More decisively, confocal fluorescence microscopy imaging from Raw264.7 cells indicated that AP could be used as an effective fluorescent probe for the analysis of Cu2+ ions in living cells. Chapter 5 reports, a new ultra stable dual functionalized gold nanoparticles (AuNPs) were developed and utilized in colorimetric naked eye assay of clenbuterol (CLB). The simple NaBH4 reduction method has been employed to dual functionalize the AuNPs by glutamic acid (Glu) and polyethylenimine (PE). Impressively, the above gold nanoparticles (PE-Glu-AuNPs) were found to be extremely stable at room temperature up to six months. Remarkably, the colorimetric assay of CLB by PE-Glu-AuNPs has been initiated at 300 nM at pH 5 and visualized through naked eyes visualized. Moreover, the UV-vis titration based sub nanomolar CLB detection has been estimated from standard deviation and linear fittings. Further to note, the aggregation induced mechanism on CLB detection was well verified through Transmission electron microscopy (TEM) and dynamic light scattering (DLS) studies. The DLS studies calculated the initial size of PE-Glu-AuNPs as 12.8 ± 8.6 nm, which was later aggregated as 84.8 ± 52.3 nm with CLB. Additionally, the TEM studies supports the above aggregation induced CLB detection. Demonstrably, the PE-Glu-AuNPs based CLB detection was not affected any other interferences. More excitingly, the sensor selectivity of PE-Glu-AuNPs to clenbuterol was also well demonstrated in human urine sample studies.
Databáze: Networked Digital Library of Theses & Dissertations
Externí odkaz: