Molecular self-assembly has enabled the fabrication of biologically inspired, advanced nanostructures as lipid-based nanovesicles (L-NVs). The oldest L-NVs, liposomes, have been widely proposed as potential candidates for drug delivery, diagnostic and/or theranostic applications and some liposome-based drug products have already stepped from the lab-bench to the market. This success is attributed to their ability to encapsulate both hydrophobic and/or hydrophilic molecules, efficiently carry and protect them within the body and finally deliver them at the target site. These positive features are also coupled with high biocompatibility. However, liposomes still present some unsolved drawbacks, such as poor colloidal stability, short shelf-life, restricted and expensive conditions of preparation because of the inherent nature of their fundamental constituents (phospholipids). The new tools available in the self-assembly of controlled molecules have significantly advanced the field of L-NV design and synthesis, and non-liposomal L-NVs have been recently developed; this new generation of nanovesicles can represent a paradigm shift in nanomedicine: they may complement liposomes, showing their advantages and overcoming most of their drawbacks. Clearly, being still young, their rocky way to the clinic first and then to the market has just started and it is still long, but they have all the potentialities to reach their objective target. The purpose of this review is to first present the large plethora of L-NVs available, focusing on this new generation of non-liposomal L-NVs and showing their similarities and differences with respect to their ancestors (liposomes). Since the overspread of a nanomaterial to the market is also strongly dependent on the availability of technological-scale preparation methods, we will also extensively review the current approaches exploited for L-NV production. The most cutting-edge approaches based on compressed fluid (CF) technologies will be highlighted here since they show the potential to represent a game-change in the production of L-NVs, favouring their step from the bench to the market. Finally, we will briefly discuss L-NV applications in nanomedicine, looking also for their future perspectives.

A scalable, single-step, synthetic approach for the manufacture of biocompatible, functionalized micro-and nanogels is presented. In particular, poly(N-vinyl pyrrolidone)-grafted-(aminopropyl)methacrylamide microgels and nanogels were generated through e-beam irradiation of PVP aqueous solutions in the presence of a primary amino-group-carrying monomer. Particles with different hydrodynamic diameters and surface charge densities were obtained at the variance of the irradiation conditions. Chemical structure was investigated by different spectroscopic techniques. Fluorescent variants were generated through fluorescein isothiocyanate attachment to the primary amino groups grafted to PVP, to both quantify the available functional groups for bioconjugation and follow nanogels localization in cell cultures. Finally, a model protein, bovine serum albumin, was conjugated to the nanogels to demonstrate the attachment of biologically relevant molecules for targeting purposes in drug delivery. The described approach provides a novel strategy to fabricate biohybrid nanogels with a very promising potential in nanomedicine.

(1) Background: A new family of nanosystems able to discern between normal and tumor cells and to release a therapeutic agent in controlled way were synthetized by e-beam irradiation. This technique permits to obtain biocompatible, sterile, carboxyl-functionalized polyvinylpyrrolidone (PVP-co-acrylic acid) nanogels (NGs); (2) Methods: Here, we performed a targeting strategy based on the recognition of over-expressed proteins on tumor cells, like the folate receptor. The selective targeting was demonstrated by co-culture studies and flow cytometry analysis, using folate conjugated NGs. Moreover, nanoparticles were conjugated to a chemotherapeutic drug or to a pro-apoptotic siRNA through a glutathione sensitive spacer, in order to obtain a controlled release mechanism, specific for cancer cells. The drug efficiency was tested on tumor and healthy cells by flow cytometric analysis, confocal and epifluorescence microscopy and cytotoxicity assay; the siRNA effect was investigated by RNAi experiment; (3) Results: The data obtained showed that the use of NGs permits a faster cargo release in cancer cells, in response to high cytosolic glutathione level, also improving their efficacy; (4) Conclusion: The possibility of releasing biological molecules in a controlled way and to recognize a specific tumor target allows overcoming the typical limits of the classic cancer therapy.

Radiation-engineered poly(N-vinyl pyrrolidone) nanogels are very interesting biocompatible nanocarriers for i.v. administration of therapeutics and contrast agents for bioimaging. The manufacturing process is fast and effective, it grants excellent control of particle size and simultaneous sterilization of the formed nanogels. Interestingly, primary amino groups and carboxyl groups, useful for (bio)conjugation, are also formed in a dose-dependent fashion. In this paper, by means of both numerical simulations and experiments, the origin of nanogel size control and functionalization is investigated. This understanding offers a new dimension for the design and production of radiation-sculptured multifunctional nanocarriers from aqueous solutions of polymers

Controlled synthesis of nanoscalar and nanostructured materials enables the development of novel functional materials with fine-tuned optical, mechanical, electronic, magnetic, conductive and catalytic properties that are of use in numerous applications. These materials have also found their potential use in medicine as vehicles for drug delivery, in diagnostics or in combinations thereof. In principle, nanoparticles can be divided into two broad categories, organic and inorganic nanoparticles. For both types of nanoparticles there are numerous possible synthetic routes. Considering the large difference in nature of these materials and the elementary reactions involved in the synthetic routes, most manufacturing techniques are complex and only suitable for one type of particle. Interestingly, radiation chemistry, i.e., the use of ionizing radiation from radioisotopes and accelerators to induce nanomaterials or chemical changes in materials, has proven to be a versatile tool for controlled manufacturing of both organic and inorganic nanoparticles. The advantages of using radiation chemistry for this purpose are many, such as low energy consumption, minimal use of potentially harmful chemicals and simple production schemes. For medical applications one more advantage is that the material can be sterile as manufactured. Radiation-induced synthesis can be carried out in aqueous systems, which minimizes the use of organic solvents and the need for separation and purification of the final product. The radiation chemistry of water is well known, as are the various ways of fine-tuning the reactivity of the system towards a desired target by adding different solutes. This, in combination with the controllable and adjustable irradiation process parameters, makes the technique superior to most other chemical methods. In this review, we discuss the fundamentals of radiation chemistry and radiation-induced synthesis of nanoparticles in aqueous solutions. The impact of dose and dose rate as well as of controlled addition of various solutes on the final particle composition, size and size distribution are described in detail and discussed in terms of reaction mechanism and kinetics.

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Polyethyleneimine (PEI) has been used extensively for transient gene expression (TGE) in mammalian cell cultures. However, the relationship between DNA/PEI complex preparation and their biological activity has not been fully established. Here, a systematic study of DNA/PEI complexes, their physicochemical properties during formation and their transfection efficiency was performed on a virus-like particle (VLP) production platform. The same chemically defined cell culture medium for DNA/PEI complex formation was used as an alternative to simple ionic solutions to minimize changes in complex properties during transfection. Upon formation, an initial concentration of 1E+10 DNA/PEI complexes/mL underwent partial aggregation with an average size of 300 nm. The participation of NaCl ions in the evolution of complexes was analyzed by X-ray spectroscopy, stressing the relevance of complexing media composition in TGE strategies. After 15 minutes incubation, 250 complexes plus aggregates per cell were estimated at the time of transfection. Such heterogeneous preparations cannot be easily characterized; subsequently, nanoparticle tracking analysis (NTA) and cryo-electron microscopy were combined to achieve a complete picture of the preparation. Finally, the contribution of each DNA/PEI complex subpopulation was tested by drug inhibition endocytosis. Interestingly, all complexes delivered DNA efficiently and high size aggregates, which enter through macropinocytosis, when inhibited presented a major contribution to transfection efficiency. There is a need to understand the physicochemical factors that participate in DNA delivery protocols. Hence, this study provides new insights into the characterization of DNA/PEI complexes that will assist in more productive and reproducible TGE strategies.

Quatsomes (QS) membrane structure and nanomechanics. Promising candidates for drug delivery based on deformable vesicles.