Riassunto analitico
Nanosystems for drug delivery have seen a continuous increase in research and applications in the last 20 years, especially regarding liposomes and polymeric nanoparticles (NPs). Both carriers show advantages in the tunability of biodegradation, biocompatibility and surface modification, but suffer a lack of an optimized industrial scale up complicated by a number of manufacturing difficulties. For example, classic benchtop methods like Thin Layer Evaporation (TLE) for liposome preparation or Nanoprecipitation for polymeric nanoparticles preparation work perfectly in small batches but could suffer from high batch to batch variability and lack of control over the size of the nanosystem when scaled up. Microfluidic techniques, in which two solutions used to manufacture the NPs are finely mixed in a micrometric environment, were widely exploited and seem to guarantee far greater control over the mixing conditions resulting in overall narrower NP size distribution due to the precise tunability of several parameters, such as the flow rate ratio of the two solutions, temperature, total flow rate and others. For this reason, microfluidics workstations were developed and commercialized, enabling the automatization and industrialization of the manufacturing process. In this work of thesis, we aimed to evaluate whether already established protocols are easily translatable into microfluidic systems’ settings, or which degree of optimization is needed. To this aim, we decided to focus on different formulations (i.e. polymeric or hybrid NPs and liposomes loaded or not with model drugs of different molecular weights and solubility) and try to establish a pre-formulative study based on a possible comparison between well established “on the bench” methods and nanoproducts, already optimized by researchers of the Nanotech group at the University of Modena and Reggio Emilia and those obtained using a workstation, NanoAssemblr® Ignite™ by Precision Nanosystem. Five features of finalized nanosystems were considered as possible reliable readouts of the different process used for nanoproduction: size and Zeta potential, size stability under different storage conditions, weight yield, encapsulation efficiency and loading content. In terms of size and homogeneity of the nanosystems, the results highlighted that Ignite™ technology allows to formulate NPs with comparable (similar or smaller) size than the ones obtained with “on the bench” methods, with relevant different in evident homogeneity values of the obtained products. Some significant differences were, on the contrary, revealed considering liposomal formulations in terms of mean size and size distribution. Considering stability, the results of stability indicated that the manufacturing process does not affect the stability of NPs highlighting that storage method at +4°C should be preferred to sub-zero temperatures. Finally, considering drug loading and encapsulation efficiency, strong variations amongst the samples were outlined, depending not only on the composition of the NPs but also on the parameters set on Ignite™ Technology. As a conclusion, this preformulative study strongly confirm that microfluidic technology (as Ignite™) could represent a useful and promising tool for production of large batches of these nanosytems, but at the same time focus on a need of a careful evaluation of the real adaptability of the microfluidic technology with requires a deep design and optimization of parameters of scale-up protocols, in terms of solvents, flow and surfactant, in function of both the type of nanosytems to be obtained and drug to be loaded into.
|
Abstract
Nanosystems for drug delivery have seen a continuous increase in research and applications in the last 20 years, especially regarding liposomes and polymeric nanoparticles (NPs). Both carriers show advantages in the tunability of biodegradation, biocompatibility and surface modification, but suffer a lack of an optimized industrial scale up complicated by a number of manufacturing difficulties. For example, classic benchtop methods like Thin Layer Evaporation (TLE) for liposome preparation or Nanoprecipitation for polymeric nanoparticles preparation work perfectly in small batches but could suffer from high batch to batch variability and lack of control over the size of the nanosystem when scaled up. Microfluidic techniques, in which two solutions used to manufacture the NPs are finely mixed in a micrometric environment, were widely exploited and seem to guarantee far greater control over the mixing conditions resulting in overall narrower NP size distribution due to the precise tunability of several parameters, such as the flow rate ratio of the two solutions, temperature, total flow rate and others. For this reason, microfluidics workstations were developed and commercialized, enabling the automatization and industrialization of the manufacturing process. In this work of thesis, we aimed to evaluate whether already established protocols are easily translatable into microfluidic systems’ settings, or which degree of optimization is needed. To this aim, we decided to focus on different formulations (i.e. polymeric or hybrid NPs and liposomes loaded or not with model drugs of different molecular weights and solubility) and try to establish a pre-formulative study based on a possible comparison between well established “on the bench” methods and nanoproducts, already optimized by researchers of the Nanotech group at the University of Modena and Reggio Emilia and those obtained using a workstation, NanoAssemblr® Ignite™ by Precision Nanosystem.
Five features of finalized nanosystems were considered as possible reliable readouts of the different process used for nanoproduction: size and Zeta potential, size stability under different storage conditions, weight yield, encapsulation efficiency and loading content.
In terms of size and homogeneity of the nanosystems, the results highlighted that Ignite™ technology allows to formulate NPs with comparable (similar or smaller) size than the ones obtained with “on the bench” methods, with relevant different in evident homogeneity values of the obtained products. Some significant differences were, on the contrary, revealed considering liposomal formulations in terms of mean size and size distribution.
Considering stability, the results of stability indicated that the manufacturing process does not affect the stability of NPs highlighting that storage method at +4°C should be preferred to sub-zero temperatures. Finally, considering drug loading and encapsulation efficiency, strong variations amongst the samples were outlined, depending not only on the composition of the NPs but also on the parameters set on Ignite™ Technology.
As a conclusion, this preformulative study strongly confirm that microfluidic technology (as Ignite™) could represent a useful and promising tool for production of large batches of these nanosytems, but at the same time focus on a need of a careful evaluation of the real adaptability of the microfluidic technology with requires a deep design and optimization of parameters of scale-up protocols, in terms of solvents, flow and surfactant, in function of both the type of nanosytems to be obtained and drug to be loaded into.
|