Development of gold core silica shell nanospheres for cancer therapy

• Autor(a) principal: Guimarães, Rafaela da Silva
• Data de Publicação: 2020
• Tipo de documento: Dissertação
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/10400.6/10552
• topic: Anisamida; Cancro; Combinação de Fármacos; Doxorrubicina; Laranja de Acridina; Nanopartículas de Núcleo de Ouro Com Revestimento de Sílica; Peg; Domínio/Área Científica::Ciências Médicas::Ciências Biomédicas

Currently, cancer is major public health problem, presenting an increasing incidence and mortality rate that affects the worldwide population. Among the treatments used in the clinic, chemotherapy is the most commonly used anticancer therapy, despite its low therapeutic efficacy. This scenario can be explained by rapid degradation, reduced solubility, and selectivity of chemotherapeutic drugs to cancer cells. Additionally, cancer cells can develop resistance to multiple drugs, which highlights the necessity to develop novel and more effective anti-cancer approaches. Combinatorial therapies based on the simultaneous administration of multiple drugs can lead to synergistic effects, which consequently increase the therapeutic efficiency of chemotherapy. However, chemotherapeutic drugs present limitations that impair their intravenous administration. Thus, despite the need to found novel drug combinations with high therapeutic potential, it is crucial to develop delivery systems capable of increasing the drugs’ therapeutic selectivity and efficacy while simultaneously decreasing their systemic toxicity. Among the drug delivery systems that have been developed so far, gold core silica shell (AuMSS) nanoparticles present excellent physicochemical and biological properties that allow their simultaneous application in chemotherapy and bioimaging. Thus, the research work developed during the second year of my master’s degree aimed to design a dual drug combination based on Doxorubicin (DOX) and Acridine orange (AO) to be encapsulated in AuMSS nanospheres. Moreover, a novel AuMSS surface modification using 3-(Triethoxysilyl)propyl isocyanate-Poly(ethylene glycol)-4- Methoxybenzamide (TPANIS) was developed to improve nanoparticles’ blood circulation time and specificity to cancer cells. The 4-Methoxybenzamide or Anisamide (ANIS) was selected due to its specificity for sigma receptors that are overexpressed in the cancer cells’ membranes. On the other hand, PEG was selected due to its amphiphilic nature and high solubility, that lead to a reduce protein adsorption on nanoparticles’ surface, and consequently increase its blood circulation time. The obtained results demonstrated that the DOX:AO drug combination can mediate a synergistic therapeutic effect in both HeLa and MCF-7 cells, particularly at the 2:1, 1:1, and 1:2 ratios. Otherwise, AuMSS nanoparticles’ functionalization with the TPANIS promoted a slight increase in the nanoparticles’ size and stability. The successful incorporation of the polymers on nanoparticles surface was also confirmed by thermogravimetric analysis (TGA) and by Fourier Transform Infrared Spectroscopy (FTIR). Additionally, both the DOX and AO were successfully encapsulated on the AuMSS-TPANIS nanospheres. In in vitro studies, nanoparticles demonstrated to be biocompatible when in contact with healthy cells (fibroblasts) and cancer cells (HeLa and MCF-7) up to the maximum tested concentration of 200 µg/mL. Moreover, the AuMSS nanospheres' functionalization with TPANIS significantly increased their internalization by MCF-7 cells. This selectivity towards MCF-7 (overexpressing sigma receptors) also resulted in an enhanced cytotoxic effect against this cell line. In summary, the presented results confirm the successful functionalization of AuMSS nanoparticles with PEG and ANIS. Additionally, the therapeutic potential of the DOX:AO drug combination as well as the targeting capacity of AuMSS-TPANIS nanospheres were also demonstrated. Such supports the application of AuMSS-TPANIS nanoparticles for cancer-targeted chemotherapy based on the DOX:AO drug combination.