Doxorubicin-containing gold nanoparticles-anchored liposomes as delivery carriers: A quality by design strategy to optimize the surface functionalization.

TORRES, JAZMIN; PRIETO-DAPENA, FRANCISCO; LONGHI, MARCELA; RABASCO, ANTONIO; GARCÍA, MÓNICA C*; GONZÁLEZ-RODRÍGUEZ, MARÍA LUISA*

Congreso; 80th International Pharmaceutical Federation (FIP) World Congress of Pharmacy and Pharmaceutical sciences; 2022

Background information. Liposomes (Lip) exhibit high biocompatibility and are attractive carrier systems for delivering anticancer drugs. They can be functionalized with gold nanoparticles (AuNPs) and are useful in cancer nanomedicine for diagnosis and treatment. Thermosensitive Lip constitute an interesting alternative as nanosystems capable of responding to thermal stimulus. Thermo-responsive Lip can be obtained by using temperature-sensitive phospholipids as well as anchoring their surface with AuNPs because of their light-induced heating response. Surface functionalization of Lip with AuNPs can affect their interfacial properties and their ability to carry and deliver the payload. Purpose. The aim of this study was to apply a quality by design (QbD) strategy to rationalize the experimental design to anchor doxorubicin (Dox)-loaded Lip with AuNPs and evaluate their performance as carrier systems.Method. Thin-film hydration and transmembrane pH-gradient methods were used to prepare the Lip and for Dox loading, respectively. Selected variables: Lip-Dox:AuNPs ratio (3:8, 8:8 and 8:3 (v/v)), stirring time (1, 2 and 3 min), temperature (4, 25 and 42 °C) and time of anchoring (0, 24 and 48 h post-functionalization) were subjected to experimental verification through variable-response correlation, using a Taguchi matrix design. Interfacial properties: hydrodynamic diameter (dH), polydispersity index (PDI) and electrokinetic potential (Z); and Dox loading efficiency (EE %) were evaluated. The data obtained were mathematically and statistically analyzed, using the DOEpack 2000 software. Variables that presented adequate levels of statistical significance (p˂0.001) were considered critical. Drug release studies toward different media (pH 7.4 and 5.1 at physiological and hyperthermal temperatures) were carried out for optimized liposomal dispersions.Results. Non-functionalized AuNPs Dox-loaded Lip exhibited nano-scale sizes (355 nm), acceptable PDI values (<0,46), and positive Z-potential (14 mV, after drug loading) because of the presence of dimethyldioctadecylammonium bromide in the bilayer. This cationic surface of Lip allowed the anchoring with negative charged AuNPs by electrostatic interactions. Lip-Dox:AuNP ratio, stirring time and temperature significantly affected the interfacial properties of AuNP-Lip-Dox. Nanometric sizes (516 nm), acceptable PDI values (<0.4), positive Z-potential (9,85 mV) and EE % equal to (80 ± 2) % were only achieved at 8:3 Lip-Dox:AuNPs ratio, 3 min of stirring time and 42 °C. When comparing the dH of empty Lip (287 nm), Dox-loaded Lip and AuNPs-Lip-Dox, it can be observed that the higher the system complexity, the higher the sizes. Although the anchoring can destabilize the Lip bilayer, Dox kept well-encapsulated and non- leakage was observed after functionalization ((78 ± 2) % and (80 ± 2) % for Lip-Dox and AuNPs-Lip-Dox, respectively). The release of Dox toward both receptor media was controlled, and as expected, its release was triggered under hyperthermia conditions (light-induced heating), confirming the thermo-responsive behavior of liposomal dispersions. Acid medium also promoted Dox release, thus demonstrating AuNPs-Lip-Dox presented pH-sensitive responsiveness.Conclusion. The QbD was a useful strategy to evaluate different parameters for surface functionalization of Lip with AuNPs that can affect their performance. Optimized conditions for the anchoring process were achieved, allowing the preparation of liposomal dispersions with thermos-responsiveness that exhibit promising properties for cancer nanomedicine and hyperthermia therapy.