Coating of gold nanoparticles with extracellular vesicles for the controlled and selective nucleic acid delivery to target cells

Cancer is a multifaceted global health issue that causes approximately ten million deaths annually, making it one of the major challenges of the 21st century. Current therapies, particularly chemotherapy, often suffer from a lack of selectivity, necessitating the development of novel anticancer strategies. Recent years have seen the emergence of targeted drug delivery approaches, leveraging targeting mechanisms to enhance specificity towards tumor sites. These approaches can be further combined with gene therapy to create systems that selectively deliver nucleic acids to target tumor cells as innovative anticancer therapeutic strategies. One of the main advantages of delivering nucleic acids rather than chemotherapeutic drugs lies in their ability to overcome the issue of drug resistance, a crucial aspect in current therapies. In this context, small interfering RNAs (siRNAs) have garnered significant interest, as these short nucleic acids can silence genes critical to tumor growth and progression.?? Nanoparticles, particularly gold nanoparticles, have emerged as optimal carriers for nucleic acids due to their multifunctional capabilities. Gold nanoparticles offer unique advantages, such as enabling combined gene and photothermal therapy, and serving as superior contrast agents for computed tomography (CT) imaging. However, these nanoparticles face challenges in protecting nucleic acids from degradation when attached to their surfaces. To address this, encapsulating functionalized gold nanoparticles within extracellular vesicles (EVs) creates a nanocomplex capable of accurately delivering the cargo to the desired target site. Despite the existence of differing opinions on the subject, some research suggests that EVs derived from tumor cells exhibit a natural tropism towards their parent cells, making them effective vehicles for selectively delivering genetic cargo.?? The objective of this study is to develop a hybrid nanosystem by encapsulating functionalized AuNPs with therapeutic nucleic acids inside EVs derived from lung cancer cells, aiming for targeted delivery to the originating cells. Initially, gold nanoparticles were synthesized using seeding growth and citrate reduction methods. After assessing the second method as the best one to proceed, the gold nanoparticles were further functionalized with a positively charged peptide for electrostatic interaction with the therapeutic nucleic acids, and with two different polymers to enhance stability. The nanosystem underwent physicochemical characterization, followed by an assessment of its cytotoxicity against tumor cells. Finally, preliminary investigations were conducted on nanoparticle encapsulation within EVs and the transfection efficiency of these systems. By the end of the work, it was concluded the feasibility of designing this complex hybrid system that could be useful for cancer theragnostic applications.