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- In situ formation of alginic acid‐gold nanohybrids for application in cancer photothermal therapyPublication . Figueiredo, André Q.; Rodrigues, Ana Carolina Félix; Fernandes, Natanael; Correia, I.J.; Moreira, André F.Gold-based nanoparticles present excellent optical properties that propelled their widespread application in biomedicine, from bioimaging to photothermal applications. Nevertheless, commonly employed manufacturing methods for gold-based nanoparticles require long periods and laborious protocols that reduce cost-effectiveness and scalability. Herein, a novel methodology was used for producing gold-alginic acid nanohybrids (Au-Alg-NH) with photothermal capabilities. This was accomplished by promoting the in situ reduction and nucleation of gold ions throughout a matrix of alginic acid by using ascorbic acid. The results obtained reveal that the Au-Alg-NHs present a uniform size distribution and a spike-like shape. Moreover, the nanomaterials were capable to mediate a temperature increase of ≈11°C in response to the irradiation with a near-infrared region (NIR) laser (808 nm, 1.7 W cm−2). The in vitro assays showed that Au-Alg-NHs were able to perform a NIR light-triggered ablation of cancer cells (MCF-7), being observed a reduction in the cell viability to ≈27%. Therefore, the results demonstrate that this novel methodology holds the potential for producing Au-Alg-NH with photothermal capacity and higher translatability to the clinical practice, namely for cancer therapy.
- Metal-Polymer Nanoconjugates Application in Cancer Imaging and TherapyPublication . Figueiredo, André Q.; Rodrigues, Ana Carolina Félix; Fernandes, Natanael; Diogo, Duarte de Melo; Correia, I.J.; Moreira, AndréMetallic-based nanoparticles present a unique set of physicochemical properties that support their application in different fields, such as electronics, medical diagnostics, and therapeutics. Particularly, in cancer therapy, the plasmonic resonance, magnetic behavior, X-ray attenuation, and radical oxygen species generation capacity displayed by metallic nanoparticles make them highly promising theragnostic solutions. Nevertheless, metallic-based nanoparticles are often associated with some toxicological issues, lack of colloidal stability, and establishment of off-target interactions. Therefore, researchers have been exploiting the combination of metallic nanoparticles with other materials, inorganic (e.g., silica) and/or organic (e.g., polymers). In terms of biological performance, metalpolymer conjugation can be advantageous for improving biocompatibility, colloidal stability, and tumor specificity. In this review, the application of metallic-polymer nanoconjugates/nanohybrids as a multifunctional all-in-one solution for cancer therapy will be summarized, focusing on the physicochemical properties that make metallic nanomaterials capable of acting as imaging and/or therapeutic agents. Then, an overview of the main advantages of metal-polymer conjugation as well as the most common structural arrangements will be provided. Moreover, the application of metallic-polymer nanoconjugates/nanohybrids made of gold, iron, copper, and other metals in cancer therapy will be discussed, in addition to an outlook of the current solution in clinical trials.
- Development of polymer-gold nanohybrids for the combinatorial therapy of cancerPublication . Figueiredo, André Filipe Quelhas; Correia, Ilídio Joaquim Sobreira; Moreira, André Ferreira; Rodrigues, Ana Carolina FélixCancer is still a major burden to public health worldwide with millions of new cases being diagnosed every year. Moreover, this disease also presents a high mortality rate, which can be justified by the difficulties in obtaining an early diagnosis, its rapid progression, and the lack of effectiveness of conventional treatments such as surgery, chemotherapy, and radiotherapy. In fact, the surgical procedure may not ensure the complete removal of the tumor cells, whereas both radiotherapy/chemotherapy present low specificity for cancer cells, causing severe side effects. Therefore, it is urgent to develop and implement new therapeutic approaches with greater selectivity and efficacy. In recent years, developments in the area of nanotechnology contributed for the emerging of novel solutions for improving the performance of electronics, medical diagnostics, and therapeutics. Particularly, for cancer therapy, the nanoparticles can be explored to develop diagnostic, imaging, therapeutic agents, or even allow the combination of all these functions in one multifunctional system. Such potential rendered the development of several different nanoparticles by varying both the raw material (e.g., polymers, ceramics, lipids, and materials) and the nanoparticles’ structure. Among them, metal-based nanoparticles are the most promising materials to create all-in-one multifunctional platforms, due to the inherent bioimaging capacity that can be combined with drug delivery or photothermal/photodynamic effects. Nevertheless, these materials often present suboptimal toxicological profiles and colloidal stability as well as off-target interactions in the human body. To address these issues, metal-based nanoparticles have been often combined with other materials such as inorganic (e.g., silica) and/or organic (e.g., polymers, like Polyethylene glycol, PEG). In this field, the metal-polymer conjugation can be highly advantageous biologically, namely by improving biocompatibility, colloidal stability, and tumor specificity. Taking this into account, the work plan developed during this MSc dissertation aimed at developing a novel synthesis approach to produce gold-alginic acid nanomaterials for application in cancer therapy. Gold is one of the most explored materials for producing metallic nanoparticles due to their promising optical properties (e.g. localized surface plasmon resonance), light-to-heat conversion efficiency, and facile surface functionalization. The alginic acid was selected due to its biocompatibility, hydrophilicity, and negative charge that was explored to guide the nanomaterials formation. For that purpose, the nanomaterials’ production was achieved by promoting gold reduction and nucleation in the presence of alginic acid and calcium chloride. The gold-alginic acid nanohybrids exhibited a spike-like shape with the reduced gold dispersed within the nanoparticle matrix. Moreover, the in situ gold reduction led to an improved absorption in the NIR (near-infrared) region, when compared to alginic acid nanoparticles, which indicated the gold-alginic acid nanohybrids potential for application in photothermal therapy. Furthermore, the colloidal stability assays demonstrated that the gold-alginic acid nanohybrids remained stable for 3 weeks, being detected a 4.7% size variation after 21 days. Otherwise, in vitro assays performed in human fibroblasts (FibH) and breast cancer cells (MCF-7) revealed that the gold-alginic acid nanohybrids were biocompatible even at the highest tested concentration of 200 µg mL-1, at 72 h of incubation. Additionally, fluorescent-based experiments showed that the nanoparticles can be efficiently internalized by cancer cells. Finally, the irradiation with a near-infrared laser (3 cycles, 808 nm, 1.7 W cm-2 for 10 min) resulted in the reduction of the MCF-7 cells’ viability to ˜27%, when a gold-alginic acid nanohybrids concentration of 200 µg mL-1 was used. In summary, the obtained results demonstrate the successful synthesis of gold-alginic acid nanohybrids. Moreover, the nanomaterials’ colloidal stability, photothermal potential, and possible application in cancer therapy were demonstrated. In the near future, the nanomaterials’ functionalization with targeting moieties (e.g., antibodies or aptamers) and the drug loading will be explored to further increase the cancer specificity of the gold-alginic acid nanohybrids and allow the development of more effective chemophotothermal combinatorial therapies. Furthermore, in vivo assays will also be performed to validate the therapeutic potential of gold-alginic acid nanohybrids.