Gold nanosphere-thioctic acid-Zn(Salophen) conjugate: Synthesis, characterisation, toxicity and protein interaction / Ng Yin Zhuang

Ng , Yin Zhuang (2022) Gold nanosphere-thioctic acid-Zn(Salophen) conjugate: Synthesis, characterisation, toxicity and protein interaction / Ng Yin Zhuang. Masters thesis, Universiti Malaya.

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Abstract

A novel inorganic metal complex gold nanoparticle conjugate was synthesised and characterised in this study. It was achieved by conjugating a Schiff base zinc complex, [N,N-bis(salicylidene)-1,2-phenylenediamine]zinc(II) or commonly known as Zn(salophen) (ZnS) to gold nanosphere with thioctic acid functioning as the linker. The conjugate (AuNS-TA-ZnS) was characterised with FTIR, UV-visible spectroscopy, fluorescence spectroscopy, dynamic light scattering (DLS) analysis, zeta potential analysis, inductively coupled plasma mass spectrometry (ICP-MS) analysis and transmission electron microscope (TEM). Both AuNS-TA-ZnS and ZnS were confirmed to be the proposed structures. The diameter of AuNS-TA-ZnS was determined to be 17.73 nm with 1785 ZnS conjugated to each gold nanosphere. The interactions of AuNS-TA-ZnS with proteins were studied. It was found that the conjugate has strong affinity to Bovine Serum Albumin (BSA). AuNS-TA-ZnS is able to alter the secondary structure of BSA without causing conformational change to the tertiary structure of BSA. Apart from demonstrating the ability to generate reactive oxygen species (ROS), AuNS-TA-ZnS also inhibits proteasome activities specifically at the Trypsin-like site of mouse 20S proteasome. Cytotoxicity study with breast cancer cells shows that AuNS-Ta-ZnS is more cytotoxic than unconjugated ZnS. Transepithelial electrical resistance (TEER) measurement across Caco-2 cell monolayer found AuNS-TA-ZnS has higher efficiency than ZnS in permeating thru the cells.

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