RT Journal Article T1 CRISPR/Cas9 Delivery Systems to Enhance Gene Editing Efficiency A1 Seijas Cerceda, Ana A1 Cora Calvo, Diego A1 Novo, Mercedes A1 Al-Soufi, Wajih A1 Sánchez Piñón, Laura A1 Arana Díaz, Álvaro Jesús K1 CRISPR K1 Cas9 K1 Gene editing K1 Delivery systems K1 Non-viral vectors K1 LNPs K1 Cas9 aggregation K1 Nanoparticle encapsulation K1 Physical delivery AB CRISPR/Cas9 has revolutionized genome editing by enabling precise and efficient genetic modifications across multiple biological systems. Despite its growing therapeutic potential, key challenges remain in mitigating off-target effects, minimizing immunogenicity, and improving the delivery of CRISPR components into target cells. This review provides an integrated analysis of physical, viral, and non-viral delivery systems, highlighting recent advances in the use of lipid nanoparticles, polymeric carriers, and hybrid platforms. We also examine an often overlooked factor: the aggregation behavior of the Cas9 protein, which may interfere with cellular uptake, the encapsulation efficiency, and nuclear localization. By comparing delivery platforms and their reported editing outcomes, we identify critical physicochemical parameters that influence therapeutic success. Finally, we propose standardized methods to assess Cas9 encapsulation and aggregation and discuss translational barriers such as manufacturing scalability and regulatory requirements. These insights aim to guide the development of safer and more effective CRISPR/Cas9-based therapies PB MDPI SN 1661-6596 YR 2025 FD 2025 LK https://hdl.handle.net/10347/43766 UL https://hdl.handle.net/10347/43766 LA eng NO Seijas, A., Cora, D., Novo, M., Al-Soufi, W., Sánchez, L., & Arana, Á. J. (2025). CRISPR/Cas9 Delivery Systems to Enhance Gene Editing Efficiency. International Journal of Molecular Sciences, 26(9), 4420. https://doi.org/10.3390/ijms26094420 NO This research was funded by a collaborative project at Campus Terra, University of Santiago de Compostela, within the framework of the Collaboration Agreement between the USC and the Department of Culture, Education, Vocational Training, and Universities, and it was also funded by the Fundación Caixa Rural Galega Tomás Notario Vacas within a project optimizing CRISPR/Cas9 genome editing to improve disease resistance in aquaculture. Additionally, this research was carried out under the framework of Spain’s Recovery and Resilience Plan, specifically under investment line n° 1 and component number 17, which includes the Complementary RTDI Plan for Marine Science. This plan is part of the Complementary RTDI Plan for the autonomous regions of Spain, including the Marine Science Program for Galicia DS Minerva RD 25 abr 2026