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The delivery of RNA across biological barriers can be achieved by encapsulation in lipid nanoparticles (LNPs). Cationic amphiphilic drugs (CADs) are pharmacologically diverse compounds with ionizable lipid-like features. In this work, we applied CADs as a fifth component of state-of-the-art LNPs via microfluidic mixing. Improved cytosolic delivery of both siRNA and mRNA was achieved by partly replacing the cholesterol fraction of LNPs with CADs. The LNPs could cross the mucus layer in a mucus-producing air-liquid interface model of human primary bronchial epithelial cells following nebulization. Moreover, CAD-LNPs demonstrated improved epithelial and endothelial targeting following intranasal administration in mice, without a marked pro-inflammatory signature. Importantly, quantification of the CAD-LNP molar composition, as demonstrated for nortriptyline, revealed a gradual leakage of the CAD from the formulation during LNP dialysis. Altogether, these data suggest that the addition of a CAD prior to the rapid mixing process might have an impact on the composition, structure, and performance of LNPs.

Buckminsterfullerene (C 60 ) has a large potential for biomedical applications. However, the main challenge for the realization of its biomedical application potential is to overcome its extremely low water solubility. One approach is the coformulation with biocompatible water-soluble polymers, such as poly(2-oxazoline)s (PAOx), to form water-soluble C 60 nanoparticles (NPs). However, uniform and defined NPs have only been obtained via a thin film hydration method or using cyclodextrin-functionalized PAOx. Here, we report the mechanochemical preparation of defined and stable C 60 :PAOx NPs by the introduction of a simple alkyne group as a polymer end-group. The presence of this alkyne bond is proven to be crucial in the mechanochemical synthesis of stable, defined sub-100 nm C 60 :PAOx NPs, with high C 60 content up to 8.9 wt %.

Long-term in vivo imaging of cells is crucial for the understanding of cellular fate in biological processes in cancer research, immunology, or in cell-based therapies such as beta cell transplantation in type I diabetes or stem cell therapy. Traditionally, cell labeling with the desired contrast agent occurs ex vivo via spontaneous endocytosis, which is a variable and slow process that requires optimization for each particular label-cell type combination. Following endocytic uptake, the contrast agents mostly remain entrapped in the endolysosomal compartment, which leads to signal instability, cytotoxicity, and asymmetric inheritance of the labels upon cell division. Here, we demonstrate that these disadvantages can be circumvented by delivering contrast agents directly into the cytoplasm via vapor nanobubble photoporation. Compared to classic endocytic uptake, photoporation resulted in 50 and 3 times higher loading of fluorescent dextrans and quantum dots, respectively, with improved signal stability and reduced cytotoxicity. Most interestingly, cytosolic delivery by photoporation prevented asymmetric inheritance of labels by daughter cells over subsequent cell generations. Instead, unequal inheritance of endocytosed labels resulted in a dramatic increase in polydispersity of the amount of labels per cell with each cell division, hindering accurate quantification of cell numbers in vivo over time. The combined benefits of cell labeling by photoporation resulted in a marked improvement in long-term cell visibility in vivo where an insulin producing cell line (INS-1E cell line) labeled with fluorescent dextrans could be tracked for up to two months in Swiss nude mice compared to 2 weeks for cells labeled by endocytosis.

Understanding the interaction between synthetic nanostructures and living cells is of crucial importance for the development of nanotechnology-based intracellular delivery systems. Fluorescence microscopy is one of the most widespread tools owing to its ability to image multiple colors in native conditions. However, due to the limited resolution, it is unsuitable to address individual diffraction-limited objects. Here we introduce a combination of super-resolution microscopy and single-molecule data analysis to unveil the behavior of nanoparticles during their entry into mammalian cells. Two-color Stochastic Optical Reconstruction Microscopy (STORM) addresses the size and positioning of nanoparticles inside cells and probes their interaction with the cellular machineries at nanoscale resolution. Moreover, we develop image analysis tools to extract quantitative information about internalized particles from STORM images. To demonstrate the potential of our methodology, we extract previously inaccessible information by the direct visualization of the nanoparticle uptake mechanism and the intracellular tracking of nanoparticulate model antigens by dendritic cells. Finally, a direct comparison between STORM, confocal microscopy, and electron microscopy is presented, showing that STORM can provide novel and complementary information on nanoparticle cellular uptake.

Nanomaterials hold potential of altering the interaction between therapeutic molecules and target cells or tissues. High aspect ratio nanomaterials in particular have been reported to possess unprecedented properties and are intensively investigated for their interaction with biological systems. Graphene oxide (GOx) is a water-soluble graphene derivative that combines high aspect ratio dimension with functional groups that can be exploited for bioconjugation. Here, we demonstrate that GOx nanosheets can spontaneously adsorb proteins by a combination of interactions. This property is then explored for intracellular protein vaccine delivery, in view of the potential of GOx nanosheets to destabilize lipid membranes such as those of intracellular vesicles. Using a series of in vitro experiments, we show that GOx nanosheet adsorbed proteins are efficiently internalized by dendritic cells (DCs: the most potent class of antigen presenting cells of the immune system) and promote antigen cross-presentation to CD8 T cells. The latter is a hallmark in the induction of potent cellular antigen-specific immune responses against intracellular pathogens and cancer.

Here we present a single-step all-aqueous approach to encapsulate biomolecules such as enzymes and proteins into stable microreactors. Key in this method is the use of spray-drying of the biomolecules of interest in combination with oppositely charged polyelectrolytes and mannitol as the sacrificial template. Remarkably, upon spray-drying in the presence of polyelectrolyte, mannitol crystallization is suppressed and the obtained amorphous mannitol offers enhanced preservation of the biomolecules' activity. Moreover, the use of mannitol allows the formation of nanopores within the microparticles upon rehydration of the microparticles in aqueous medium and subsequent dissolution of the mannitol. The oppositely charged polyelectrolytes provide a polymeric framework which stabilizes the microparticles upon rehydration. The versatility of this approach is demonstrated using horseradish peroxidase as the model enzyme and ovalbumin as the model antigen., (© 2011 American Chemical Society)