Professor M.P.Pileni research has been highly interdisciplinary over my entire scientific career. Her accomplishments have impacted the broad area of photochemistry, photobiology, solar energy conversion, nanomaterials, colloidal assembly and self-assembly. She started her scientific carrier by investigating the reaction mechanism for the gas phase photoisomerization of pyrazine to pyrimidine and then focused her attention on problems of greater biological and pharmacological relevance. Specifically, she explored the photophysical processes of tyrosine, trytophan and other derivatives in aqueous solutions. After the second oil price rise in 1978, Professor M.P.Pileni undertook research in solar energy materials. She developed micro-heterogeneous systems to mediate charge separation between the primary photolysis products and hence to increase the efficiency of photo- to chemical energy conversion [FA1]. Full exploitation of the nanocompartments and reactivity control therein requires a molecular-level understanding of the structure of the employed colloidal systems [FA2]. She developed a geometric model [FA3], supported by kinetic approaches, to show a remarkable dependence of the average location of the reactants in the colloidal system on both the chemical and photochemical reactivity [FA5]. Professor M.P.Pileni pioneered the use of a new series of functionalized surfactants in which the counter ion was the reactive species and, again for the first time, she identified, with such surfactants, the existence of the supraaggregates made up of several colloidal phases in equilibrium. She demonstrated that these supraaggregates are predicted from a parameter as simple as the shape of the surfactant making up these entities. Such supraaggregates are largely produced in the food industry and explain the stability of several emulsions [FA8]. She extended her studies to colloids containing proteins and enzymes. Structural studies of organized molecular systems containing proteins and/or enzymes have enabled me to demonstrate, both experimentally and theoretically, large modifications of the structural properties of colloids with the appearance of percolation phenomena in diluted systems. She showed that these phenomena are due to the sum of the interaction potentials between reverses micelles and macrolecules. The control of chemical reactivity, through the study of structure-reactivity relationships, enabled her to propose a pathway for the chemical synthesis of nanomaterial products. She pioneered the use of reverse micelles in the form of nanoreactors to control size and shape of the in situ nanocrystals generated therein [FA2]. At this time (1985), this domain still appeared to belong to science fiction or scientific utopias looking for discoveries of new structures with extraordinary properties. She demonstrated that some molecules or electrolytes could also play a key role in controlling the shape of these nanocrystals. Thus, Professor M.P.Pileni can “manipulate” the atoms in order to produce nanocrystals with different shapes (spheres, cylinders, rods, disks, cubes, etc.)[FA10]. Very recently, she found that the homogeneous growth of fcc metal nuclei (single domains and multiply-twinned particles or MTPs) can lead to nanocrystals having the same shapes as the initial clusters [FA11]. This study was supported by experiments and by optical simulations using the discrete dipole approximation (DDA). This also allows her to claim that, in highly pure media, the same crystal shape exists at various scales from clusters to the bulk phase. Using reverse micelles as nanoreactors, she chemically modified enzymes and proteins in order to make them hydrophobic without changing their activity. This has opened a new approach to enzyme catalysis. Furthermore, she proved that percolation and “liquid-gas” transitions depend on the electrostatic interactions between the micelle interface and the macromolecule and not on the hydrophobic interactions, which are too weak to significantly perturb the structure. Starting in 1992, She developed a new route to synthesize ferrite nanocrystals by using normal micelles. This synthesis is now widely used both in fundamental and applied research. One of its specific features is the production of controlled-diameter nanocrystals characterized by an identical surface state. This makes it possible to ascertain the magnetic properties of the nanomaterial itself and not those resulting from the surface state changes, as is the case in the so-called classic techniques used to produce magnetic fluids. This also allows controlling the stoechiometry of the ferrite nanocrystals. In 1995, she demonstrated that nanocrystals are able to self-organize into close-packed networks (2D) and also in thin fcc superlattices (3D). Later on, the stacking of more than hundred layers of nanocrystals enabled the formation of supracrystals (3D) with fcc, hcp, or bcc structures in thermodynamically stable states. Other types of self-organization of nanocrystals like rings or honeycomb arrangements, linked to the Marangoni instabilities, were produced. She demonstrated, for the first time, that the van der Waals type interaction is one of the key parameters in the alignment of magnetic nanocrystals in a magnetic field and control the shape of mesoscopic film of nanocrystals.
In the last decade, one of her major breakthroughs was to demonstrate that the physical properties of nanocrystals self-ordered in close-packed networks (2D) are neither those of isolated nanocrystals nor those of the bulk phase of the same material. Actually, each nanocrystal influences its neighbors and their assembly is characterized by collective physical properties. These properties are due to dipolar interactions. Hence, due to the ordering in close-packed networks, the appearance of coupled plasmon modes has been observed experimentally, in agreement with theoretical predictions. The magnetic properties of nanocrystals markedly change when the magnetic nanocrystals are ordered in 1D and 2D. Furthermore, the collective magnetic properties of 3D magnetic nanocrystals self-organized on a mesoscopic scale markedly differ from the shape of the mesostructure.
Another breakthrough is related to the following question: “Does the ordering of nanocrystals in supracrystals induce intrinsic properties?” In 2005 and confirmed in 2008 by a direct proof, she found collective vibrational properties of Ag and Co nanocrystals self-assembled in fcc supracrystals. According to News & Views in Nature Material (2005, 4, 364-365), “these materials are not only statically highly ordered on a nanometer scale but also exhibit intrinsic dynamic behavior”. Other intrinsic properties like electronic, magnetic, mechanical and crystal growth have been discovered. It has been found, for example, the electronic properties change with the nanocrystals ordering in 0D, 2D and thin 3D. Very recently, she discovered that with fcc Co supracrystals there is a lower distribution of interaction energies, an inhibition of the flipping of the super-spins and a slower approach to magnetic saturation compared to the disordered aggregates. Furthermore, when magnetic nanocrystals are exposed to an external magnetic field, fcc columns are produced whereas labyrinthines are formed with disordered assemblies (2005). Triangular fcc single crystals, observed under ultra-high vacuum at a high temperature (340°C), are produced by mild annealing (50°C) from ordered Ag nanocrystals. The size of the triangles is correlated to the size of the ordered domains.
Two other breakthroughs have been made (2008): (1) crack patterns in magnetic nanocrystal films follow a universal scaling law with the film height over three orders of magnitude and (2) splitting of vibrational quadrupolar mode related to nanocrystallinity.
Most significantly, she has demonstrated an unprecedented control of chemical reactivity in colloidal systems and established novel physical principles, which govern the assembly of nanocrystals into supramolecular structures of great potential applicability.

Significantly Professor M.P.Pileni demonstrated an unprecedented control of chemical reactivity in colloidal systems and established novel physical principles, which govern the assembly of nanocrystals into supramolecular structures of great potential applicability. In summary her major breakthroughs are:
1- A fundamental understanding of the kinetics and mechanisms in colloidal solutions guided me in the preparation of either nanocrystals with different sizes and shape or the chemical modification of enzymes.
2- Formation of thermodynamically stable states of self-assemblies either by using surfactant molecules (supraaggregates) or inorganic nanocrystals (supracrystals).
3- Collective optical and magnetic properties induced by dipolar interactions and due to the nanocrystal arrangements in 1D, 2D and 3D superlattices.
4- Intrinsic mechanical, vibrational and magnetic properties due to the nanocrystals ordering in fcc supracrystals.
5- Electronic properties due to the nanocrystal arrangements in 0D, 2D and 3D superlattices.

Professor Pileni’s accomplishments have been recognized by the increasing frequency of invitations to be a plenary lecturer at international scientific meetings, symposia and congresses. International awards have recognized the importance of her contributions to these fields. She received the Langmuir prize of the American Chemical Society (2000), the prize of the Colloid Division of the Japanese Chemical Society (2001), the prize of the Alexander von Humboldt foundation in Germany (2003), the Descartes-Huygens prize in the Netherlands (2004), the Blaise Pascal Medal from the European Academy (2005) and Emila Valori Award from French Academy of Sciences (2006). In 2002, she was given the degree of Doctor Honoris Causa of the University of Chalmers at Göteborg (Sweden). She is member of European Academy of Sciences (2003) and of the Royal Academy of Sciences and Technology of Sweden (2004). She was awarded the prize of the most cited French scientist, from 1981 to 1998, in 2000 by the Institute of Scientific Information. According to Science Watch (July-August 2003) she is the 25th highest cited scientist on nanotechnology with 9.64 citation per paper. Her Hirsch factor and the sum of the times cited information are 56 and 11494 respectively (ISI). Prof. Pileni is chair of Institut Universitaire de France (2005) and of the scientific committee of the engineering and material sciences division of the European academy of sciences (2006-2009).