Synthesis
Development of consistent synthesis protocols for inorganic nanoparticles. The rapid injection of organometallic reagents in a hot solvent in presence of surfactants (and reducers in some cases) molecules produces a temporally discrete homogeneous nucleation employed for the production of monodisperse semiconductor and metallic passivated nanoparticles. The decomposition and nucleation occurs rapidly upon injection. The lifetime of individual atoms in solution is short, and many small metal clusters (nuclei) form simultaneously. The surfactants have the ability to control the size and shape of the growing particles (through thermal-dependent selective attachment) by dynamically coating the particles with a close-packed monolayer of coordinating ligand. In addition, the surfactant layer prevents the agglomeration of particles, allows monomers to add or subtract, passivates the nanoparticles against oxidation and defines the minimum interparticle distance. These conditions may lead to extremely narrow size distributions of a large number of stable nanoparticles.
Characterization
The systematic study of the structure of the particles and its correlation with the observed physico-chemical properties is a key aspect since it allows connection and feed-back between the synthesis and the final material properties. The crystal structure is studied with macroscopic (XRD) and local (electrons from a transmission electron microscope) probes. The stability of these crystal structures (annealing experiments) and their defects is studied as a function of the size, shape and chemical composition. Advanced photon and neutron sources are also used, for the refinement of the structures. Electron beams locally study the chemical composition (EDAX and EELS). Scanning probes such as atomic and magnetic force microscopy and scanning tunnelling microscopy are also used when appropriate.
Self-Assembly
Spontaneous self-assembly of molecular and nanoscale objects reflects information coded in the individual components, it is an essential part of nanotechnology, and it has a central role in life; for example, the components of a cell replicate and self-assemble into another cell during mitosis. Therefore, some developments in nanotechnology strongly rely on a “bottom-up” self-assembly approach where devices comprised of individual molecules or nanoparticles perform functions analogous to those of current technology, which should deliver more efficient systems in terms of the energy needed to produce them and implementing Nature’s multifunctionality. Nanoparticles self assembly phenomena are commonly observed but only partially explained or understood. The remaining question being through which series of events the nanoparticles from a colloidal solution form the self assembled structures upon evaporation of the solvent. Some appealing examples are extended 2D monolayers, bimodal arrays, 3D super crystals of one or different types of particles, structures formed by applying an external magnetic field, chains and ring shapes, etc.
Nanoparticles and Biology
Nanomaterials have received enormous attention for their potential applications in biology and medicine (a revolutionary technology to address single molecules and work inside the cell). This coming revolution in life sciences may exceed our current expectations and new to come. However fundamental studies in molecular mechanics, biodistribution, immune barrier trespassing, remote and local activation and health/environment impact among others are needed in a simultaneous approach to ensure sustained and successful breakthroughs. Thus, nanoparticles (NP) can be tailored with different properties such as fluorescence or magnetic moment. These properties can be harnessed to use them as local nano-probes or nano-manipulators in biological and medical applications (e.g. fluorescence labelling of cellular compartments, use of fluorescent or magnetic particles as contrast agents, magnetic separation, targeted drug delivery). Besides, NP derivatized with biological molecules have successfully been applied in materials science and biological research in recent years. NP biopolymer (like proteins or DNA) conjugates hold great promise both for biological diagnostics, where the NP can provide unique detection signatures, and for nanotechnology, where the information content of the biomolecule can be harnessed for spatial patterning of NPs. There are many strategies available for bioconjugation of NP, including attachment to biopolymers like elastin, antisense, biotin-avidin, antigen-antibodies, peptides, proteins, etc. Among the many biological polymers that can be coupled to NP, proteins are of particular interest, because of their inherent programmability and biological activity.
Nanoparticles and Proteins
Proteins are known to experience conformational changes that results in an increment of the exposition of hydrophobic residues and as a consequence reduced solubility. Afterwards, these misfolded proteins may self-assemble into insoluble fibrous deposits causing diseases called amyloidosis (Alzheimer, Parkinson, Huntington and type II Diabetes among others). We would like to develop our pioneer works on the study and the treatment of disease-causing protein folding. House made Au nanoparticles purified, conjugated with peptide-amyloid inhibitors have been prepared and selectively attached to the proteins deposits formed, as cause or consequence, of those diseases. Then a controlled electromagnetic wave has been irradiated onto the amyloid-inhibitor-nanoparticle conjugate producing a re-dissolution of the deposit without any bulk heating. By controlling the dissipated energy and the local distribution of the nanoparticles (TEM) we are succeeding in studying the structure and behaviour of the protein deposits.
Science awareness, science education and science communication
"The most beautiful experience we can have is the Mysterious. It is the fundamental emotion that stands at the cradle of true art and true science. Whoever does not know it and can no longer wonder, no longer marvel, is as good as dead, and his eyes are dimmed.” Albert Einstein, The World As I See It 1931.
My science divulgation activity is devoted to excite scientific vocation. Since I finished my postdoctoral studies, I started activities in science communication to non specialised audiences, through divulgative talks, and NP-self assembly microscopy pictures. This brought me in contact with other creative communities, as artist and open source software developers. I benefit from this relationship: on one side our speech has to be crystal-clear in order to pass it to non specialized audiences and on the other, their collaborative organization and creative mechanisms taught me about team organization and creative exploration.
