Gold nanoparticles (GNPs)-synthesis and characterizations for cancer diagnosis

Abstract

Radiopharmaceuticals play a crucial role in the diagnosis, treatment, and monitoring of various diseases by attaching radionuclides to a suitable carrier. Among these carriers, gold nanoparticles (GNPs) have gained significant attention due to their unique physicochemical properties, including their potential as radiosensitizers and optical imaging agents in cancer detection. Their capacity to transport a greater quantity of radionuclides renders them exceptionally appropriate for applications in nuclear medicine, including Single Photon Emission Computed Tomography (SPECT) and Positron Emission Tomography (PET) imaging. Additionally, the Enhanced Permeability and Retention (EPR) effect further enhances tumour targeting by enabling prolonged accumulation of radiolabeled nanoparticles in cancerous tissues, leading to improved therapeutic efficacy. In this study, we utilized gold nanoparticles (GNPs) as carriers for targeted radiotherapy and imaging applications. The high atomic number of gold enhances dose deposition, significantly improving the effectiveness of radionuclide therapy. To optimize their performance, we focused on synthesizing ultra-small GNPs, as nanoparticles within the 1–100 nm range exhibit controllable properties e.g size dependent optical properties and surface reactivity, making them ideal for biomedical applications. Various surface modifications were explored to improve dispersibility and biocompatibility, enhancing the potential for future targeted applications. Initially, modifications with cysteine, cysteamine, polyethylene glycol (PEG), polyethyleneimine (PEI), and glutathione (GSH) were attempted. However, only GSH-stabilized GNPs were selected due to their superior stability, ultra-small size, and effective thiol (-SH) attachment to the gold surface, facilitating better radiolabeling. Further modifications included ethylenimine and aziridine coatings to introduce amine (-NH₂) functional groups, improving targeting and radiolabeling efficiency. Peptide conjugation was performed to create tumour-specific targeting probes for breast cancer cells. The synthesized nanoparticles were characterized using various analytical techniques, including UV-VIS spectroscopy, Transmission Electron Microscopy (TEM), Dynamic Light Scattering (DLS), Zeta potential analysis, Fluorescamine analysis, and Fourier Transform Infrared Spectroscopy (FTIR). These characterizations confirmed the colloidal stability, size, and surface functionalization of the modified GNPs, ensuring their suitability for further biological studies.