Publications

The principles for the selection of the stereochemistry of phospholipids of biological membranes remain unclear and continue to be debated. Therefore, any new experiments on this topic may help progress in this field. To address this question, three libraries of constitutional isomeric glycerol-amphiphilic Janus dendrimers (JDs) with nonsymmetric homochiral, racemic, and symmetric achiral branching points were synthesized by an orthogonal-modular-convergent methodology. These JDs amplify self-assembly, and therefore, monodisperse vesicles known as dendrimersomes (DSs) with predictable dimensions programmed by JD concentration were assembled by rapid injection of their ethanol solution into water. DSs of homochiral JD enantiomers, racemic, including mixtures of different enantiomers, and achiral exhibited similar DS size-concentration dependence. However, the number of bilayers of DSs assembled from homochiral, achiral, and racemic JDs determined by cryo-TEM were different. Statistical analysis of the number of bilayers and coarse-grained molecular dynamics simulations demonstrated that homochiral JDs formed predominantly unilamellar DSs. Symmetric achiral JDs assembled only unilamellar DSs while racemic JDs favored multilamellar DSs. Since cell membranes are unilamellar, these results indicate a new rationale for nonsymmetric homochiral vs racemic selection. Simultaneously, these experiments imply that the symmetric achiral lipids forming more stable membrane, probably had been the preferable assemblies of prebiotic cell membranes.

JTD Keywords: architectures, cells, dendritic dipeptides, glycodendrimersomes, liposomes, organization, polymers, systems, vesicles, Drug-delivery

Building functional mimics of cell membranes is an important task toward the development of synthetic cells. So far, lipid and amphiphilic block copolymers are the most widely used amphiphiles with the bilayers by the former lacking stability while membranes by the latter are typically characterized by very slow dynamics. Herein, we introduce a new type of Janus dendrimer containing a zwitterionic phosphocholine hydrophilic headgroup (JDPC ) and a 3,5-substituted dihydrobenzoate-based hydrophobic dendron. JDPC self-assembles in water into zwitterionic dendrimersomes (z-DSs) that faithfully recapitulate the cell membrane in thickness, flexibility, and fluidity, while being resilient to harsh conditions and displaying faster pore closing dynamics in the event of membrane rupture. This enables the fabrication of hybrid DSs with components of natural membranes, including pore-forming peptides, structure-directing lipids, and glycans to create raft-like domains or onion vesicles. Moreover, z-DSs can be used to create active synthetic cells with life-like features that mimic vesicle fusion and motility as well as environmental sensing. Despite their fully synthetic nature, z-DSs are minimal cell mimics that can integrate and interact with living matter with the programmability to imitate life-like features and beyond. This article is protected by copyright. All rights reserved.This article is protected by copyright. All rights reserved.

JTD Keywords: biological-membranes, bottom-up synthetic biology, chain, hybrid vesicles, hydroethidine, organization, polymersome, proteins, stability, synthetic cells, thickness, vesicle fusion, vesicle motility, vesicles, zwitterionic dendrimersomes, Biosensor, Biosensors, Bottom-up synthetic biology, Hybrid vesicles, Lipid-bilayers, Synthetic cells, Vesicle fusion, Vesicle motility, Zwitterionic dendrimersomes

The development of contrast agents based on fluorescent nanoparticles with high brightness and stability is a key factor to improve the resolution and signal-to-noise ratio of current fluorescence imaging techniques. However, the design of bright fluorescent nanoparticles remains challenging due to fluorescence self-quenching at high concentrations. Developing bright nanoparticles showing FRET emission adds several advantages to the system, including an amplified Stokes shift, the possibility of ratiometric measurements, and of verifying the nanoparticle stability. Herein, we have developed Forster resonance energy transfer (FRET)-based nanovesicles at different dye loadings and investigated them through complementary experimental techniques, including conventional fluorescence spectroscopy and super-resolution microscopy supported by molecular dynamics calculations. We show that the optical properties can be modulated by dye loading at the nanoscopic level due to the dye's molecular diffusion in fluid-like membranes. This work shows the first proof of a FRET pair dye's dynamism in liquid-like membranes, resulting in optimized nanoprobes that are 120-fold brighter than QDot 605 and exhibit >80% FRET efficiency with vesicle-to-vesicle variations that are mostly below 10%.

JTD Keywords: Bright, Dendrimers, Fluorescent, In-vivo, Nanoparticles, Nir, Particles

The integration of active cell machinery with synthetic building blocks is the bridge toward developing synthetic cells with biological functions and beyond. Self-replication is one of the most important tasks of living systems, and various complex machineries exist to execute it. In Escherichia coli, a contractile division ring is positioned to mid-cell by concentration oscillations of self-organizing proteins (MinCDE), where it severs membrane and cell wall. So far, the reconstitution of any cell division machinery has exclusively been tied to liposomes. Here, the reconstitution of a rudimentary bacterial divisome in fully synthetic bicomponent dendrimersomes is shown. By tuning the membrane composition, the interaction of biological machinery with synthetic membranes can be tailored to reproduce its dynamic behavior. This constitutes an important breakthrough in the assembly of synthetic cells with biological elements, as tuning of membrane-divisome interactions is the key to engineering emergent biological behavior from the bottom-up.

JTD Keywords: Bacterial cell division, Bottom-up synthetic biology, Dendrimersomes, Dynamic min patterns, Dynamics, Ftsz assembly, Ftsz filaments, Mind, Organization, Pole oscillation, Polymersome membranes, Proteins, Rapid pole, Synthetic cells, Vesicles

Nowadays, amino terminal dendrimers are appealing materials for biological applications due to their multivalence and the versatile conjugation of the amino groups. However, the high reactivity of these terminal groups can be decreased by steric hindrance, limiting their possible bioapplications. Herein, we report the divergent synthesis of slightly sterically hindered amino terminal polyamide dendrimers. A simple and unique AB(2) scaffold has been chosen to build the dendritic structures, where only amide bonds have been used as the connecting unit. The 1-7 relative positions of the amino groups in the AB(2) monomers avoid the steric congestion of the macromolecules, allowing the construction of robust dendrimers up to the fifth generation. The construction of the dendrimers is based on two well-established reactions, using simple and cheap reactants, with yields above 90% on a gram scale and easy purification procedures. This synthetic methodology constitutes an easy and efficient way for the preparation of stable and aqueous soluble dendrimers on a gram scale, representing a substantial improvement over the synthesis of this kind of aliphatic polyamide amino terminal dendrimer. The prepared structures were completely characterized and evaluated by size exclusion chromatography, diffusion ordered spectroscopy and atomic force microscopy to determine their size. Molecular dynamics simulations were also carried out and the values obtained were consistent with the experimentally determined values.

JTD Keywords: Density, Discovery, Pamam dendrimers, Polymers

It can be foreseen that in a future scenario of malaria eradication, a varied armamentarium will be required, including strategies for the targeted administration of antimalarial compounds. The development of nanovectors capable of encapsulating drugs and of delivering them to Plasmodium-infected cells with high specificity and efficacy and at an affordable cost is of particular interest. With this objective, dendritic derivatives based on 2,2-bis(hydroxymethyl)propionic acid (bis-MPA) and Pluronic® polymers have been herein explored. Four different dendritic derivatives have been tested for their capacity to encapsulate the antimalarial drugs chloroquine (CQ) and primaquine (PQ), their specific targeting to Plasmodium-infected red blood cells (pRBCs), and their antimalarial activity in vitro against the human pathogen Plasmodium falciparum and in vivo against the rodent malaria species Plasmodium yoelii. The results obtained have allowed the identification of two dendritic derivatives exhibiting specific targeting to pRBCs vs. non-infected RBCs, which reduce the in vitro IC50 of CQ and PQ by ca. 3- and 4-fold down to 4.0 nm and 1.1 μm, respectively. This work on the application of dendritic derivatives to antimalarial targeted drug delivery opens the way for the use of this new type of chemicals in future malaria eradication programs.

JTD Keywords: Antimalarial targeted drug delivery, Dendrimers, Malaria, Nanomedicine, Plasmodium, Polymeric nanoparticles

Malaria is arguably one of the main medical concerns worldwide because of the numbers of people affected, the severity of the disease and the complexity of the life cycle of its causative agent, the protist Plasmodium sp. The clinical, social and economic burden of malaria has led for the last 100 years to several waves of serious efforts to reach its control and eventual eradication, without success to this day. With the advent of nanoscience, renewed hopes have appeared of finally obtaining the long sought-after magic bullet against malaria in the form of a nanovector for the targeted delivery of antimalarial drugs exclusively to Plasmodium-infected cells. Different types of encapsulating structure, targeting molecule, and antimalarial compound will be discussed for the assembly of Trojan horse nanocapsules capable of targeting with complete specificity diseased cells and of delivering inside them their antimalarial cargo with the objective of eliminating the parasite with a single dose. Nanotechnology can also be applied to the discovery of new antimalarials through single-molecule manipulation approaches for the identification of novel drugs targeting essential molecular components of the parasite. Finally, methods for the diagnosis of malaria can benefit from nanotools applied to the design of microfluidic-based devices for the accurate identification of the parasite's strain, its precise infective load, and the relative content of the different stages of its life cycle, whose knowledge is essential for the administration of adequate therapies. The benefits and drawbacks of these nanosystems will be considered in different possible scenarios, including cost-related issues that might be hampering the development of nanotechnology-based medicines against malaria with the dubious argument that they are too expensive to be used in developing areas.

JTD Keywords: Dendrimers, Liposomes, Malaria diagnosis, Nanobiosensors, Nanoparticles, Plasmodium, Polymers, Targeted drug delivery

Antimicrobial peptide drugs are increasingly attractive therapeutic agents as their roles in physiopathological processes are being unraveled and because the development of recombinant DNA technology has made them economically affordable in large amounts and high purity. However, due to lack of specificity regarding the target cells, difficulty in attaining them, or reduced half-lives, most current administration methods require high doses. On the other hand, reduced specificity of toxic drugs demands low concentrations to minimize undesirable side-effects, thus incurring the risk of having sublethal amounts which favour the appearance of resistant microbial strains. In this scenario, targeted delivery can fulfill the objective of achieving the intake of total quantities sufficiently low to be innocuous for the patient but that locally are high enough to be lethal for the infectious agent. One of the major advances in recent years has been the size reduction of drug carriers that have dimensions in the nanometer scale and thus are much smaller than -and capable of being internalized by- many types of cells. Among the different types of potential antimicrobial peptide-encapsulating structures reviewed here are liposomes, dendritic polymers, solid core nanoparticles, carbon nanotubes, and DNA cages. These nanoparticulate systems can be functionalized with a plethora of biomolecules providing specificity of binding to particular cell types or locations; as examples of these targeting elements we will present antibodies, DNA aptamers, cell-penetrating peptides, and carbohydrates. Multifunctional Trojan horse-like nanovessels can be engineered by choosing the adequate peptide content, encapsulating structure, and targeting moiety for each particular application.

JTD Keywords: Antibodies, Aptamers, Dendrimers, Liposomes, Nanomedicine, Nanoparticles, Nanovectors, Targeting