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- G-quadruplex aptamer-functionalized liposomes for lung cancer therapyPublication . Leitão, Daniela Ramos Vaz; Cruz, Carla Patricia Alves Freire Madeira da; Figueiredo, Joana Patrícia RodriguesLung cancer (LC) has the greatest impact on mortality rates worldwide, particularly nonsmall cell lung cancer (NSCLC). The treatment of NSCLC depends on the stage of the disease and may involve a combination of surgery, chemotherapy, radiotherapy or immunotherapy. However, these therapies have some limitations, since that most patients develop resistance to treatments and also have side effects. In this sense, the aptamers have emerged as a promising strategy in delivery systems for NSCLC therapies. Aptamers are known as chemical antibodies since they can bind to proteins with high specificity. In addition, they have several advantages over antibodies, such as great stability and lower immunogenicity. AT11-L2 is a derivative of the AS1411 aptamer that contain a guanine-rich sequence capable of adopting a G-quadruplex (G4) structure and therefore targets nucleolin (NCL), a protein overexpressed in the cell membrane of NSCLC cells. Thus, the aim of this study was to develop two liposomal systems containing encapsulated doxorubicin and BRACO-19 and AT11-L2 on the surface to target NCL. To this end, the structure of AT11-L2 was first characterized by biophysical studies, and then the interaction of the aptamer with the ligands was studied through molecular dynamics simulations. In addition, the potential of the ligands to stabilize AT11-L2 was also assessed by biophysical studies. Liposomes were then synthesized and characterized. Finally, the selectivity and cellular uptake of the functionalized liposomes containing the compounds were tested on human alveolar basal epithelial adenocarcinoma cells (A549) and human fetal lung fibroblast cells (MRC-5). The results showed that AT11-L2 adopts a G4 structure in the presence of K+ and when associated with PhenDC3 through p-p stacking interactions, increases its stability. In addition, the AT11-L2/NCL complex was shown to have a high affinity with a KD in the nanomolar range. In vitro studies showed that functionalized liposomes containing BRACO-19 and doxorubicin were selectively internalized by cancer cells, with greater selectivity being recorded for liposomes with doxorubicin. These results show the therapeutic potential of liposomes functionalized with AT11-L2 against NSCLC.