Gold nanorod based nanoprobes for biomedical applications

  • Zendesha Stephen Mbalaha

Student thesis: Doctoral Thesis

Abstract

Small gold nanorods (SGNRs) are nanorods that are ~13-50 nm in length and less than 10 nm in diameter. The SGNRs manifest excellent optical properties arising from localised surface plasmon resonance including strong optical absorption and scattering tunable from the visible to the infrared region of electromagnetic spectrum. The SGNRs have higher absorption to scattering ratio compared to the large gold nanorods (LGNRs), making the SGNRs good photothermal agents. Moreover, the SGNRs have ease of subcellular accessibility, high internalization rate and large surface area to volume ratio for binding of analytes. These attributes make the SGNRs good candidates in various biomedical applications such as biosensing, imaging and delivery of drugs. This study is aimed at developing gold nanorod based nanoprobes for detecting molecular biomarkers at the single cell level, and characterization of the optical properties and the photothermal effects of gold nanorods for photothermal therapy of cancer. A systematic study on the growth conditions was carried out and a reliable method has been developed for the synthesis of stable SGNRs with good control over size and shape, and high yield of rods. The SGNRs were successfully functionalized with hairpin DNA (hpDNA) for targeting messenger RNA (mRNA). Moreover, this work investigated the influence of gold nanorods size and media on their photothermal effect. Theoretical calculation revealed that the SGNRs have higher photothermal efficiency than the LGNRs in solution. However, in solution the SGNRs generated slightly more heat at off-resonance illumination while the LGNRs generated more heat than SGNRs at plasmon resonance excitation. Nevertheless, the experimental study revealed that the SGNRs generated more heat than the LGNRs when both are in gel media that is close to cell enviroment. Furthermore, aptamer functionalized SGNRs nanoprobes were developed for targeting cancer cells. The SGNRs based nanoprobes were found to have higher photothermal effect in cancer cells compared to the LGNRs nanoprobes. In addition, the SGNR based nanoprobes were found to be more sensitive than the LGNR based nanoprobes in detecting RNA cancer biomarkers in cells and exosomes. iv This work demonstrates the capability of the gold nanorod based nanoprobes in detecting the cancer biomarker RNA in a blood serum.
Date of Award4 Mar 2021
Original languageEnglish
Awarding Institution
  • University Of Strathclyde
SponsorsUniversity of Strathclyde
SupervisorYu Chen (Supervisor) & David Birch (Supervisor)

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