Membrane nanoprecipitation: From basics to technology development

The high potential of nanomaterials in different fields, from aerospace applications to healthcare technology and medical diagnostics, requires new production methods to build and control particle structure properties in large-scale manufacturing with lower energy and material consumption to enable wide penetration of the industrial sector. Membrane technology is an extremely promising, environmentally friendly and scalable method for nanoparticles (NPs) production with tremendous impact in terms of formulation quality, energy consumption reduction and waste minimization. Among the membrane-based processes for particles production, membrane nanoprecipitation (MN) is emerging as a scalable and efficient method for particles engineering at nanoscale. This review provides a detailed analysis of the current developments and efforts in the application of membrane technology for the fabrication of NPs (polymeric, liposomes and drug nanocrystals) by nanoprecipitation. In the MN process, two miscible phases (called “solvent” - which contains a solute - and “non-solvent” - which does not dissolve the solute) are separated by a membrane and meet at the pore mouth, where they mix and cause precipitation of the solute in the form of NPs. This review aims to highlight the mechanism of MN and identify the parameters that control the process. The influence of chemical parameters (such as type of solvent, non-solvent and solute), fluid-dynamic parameters (flux, wall shear stress, flow mode of operation) and membrane parameters (pore size, membrane surface wettability, pore shape and interpore distance) on the resulting nanoparticle size and size distribution was analysed. The performance of MN and other methods for producing NPs (mixing devices and microfluidics) was compared. The emerging studies on nanoprecipitation combined with membrane technology open a new window for the application of membrane science in the production of NPs to achieve a fine control of the mixing process with good accuracy and high productivity. [Display omitted] •Membrane nanoprecipitation (MN) is an emerging membrane contactor process.•The membrane promotes efficient mixing of solvent and non-solvent at the pore opening.•The membrane acts as a high throughput supersaturation system.•The formation of nanoparticles (NPs) is determined by the thermodynamics of the system.•NPs with size smaller than the pore size are obtained.