The self-assembly of a blue-emitting light-harvesting organogelator and specifically designed highly fluorescent tetracenes yields nanofibers with tunable emissive properties. In particular, under near-UV excitation, white light emission is achieved in organogels and dry films of nanofibers. Confocal fluorescence microspectroscopy demonstrates that each individual nanofiber emits white light. A kinetic study shows that an energy transfer (ET) occurs between the blue-emitting anthracene derivative and the green- and red-emitting tetracenes, while inter-tetracene ETs also take place. Moreover, microscopy unravels that the nanofibers emit polarized emission in the blue spectral region, while at wavelengths higher than 500 nm the emission is not significantly polarized.

The fabrication of highly effective antimicrobial materials is an important strategy for coping with the growing concern of bacterial resistance. In this study, N-chloramine-functionalized hollow hemispherical structures were designed and prepared to examine possible enhancement of antimicrobial performance. Antimicrobial testing was carried out on Gram-negative (Escherichia coli) and Gram-positive (Baccilus Cereus) bacteria in the presence and absence of biological medium. The efficacy of the hollow hemispherical particles functionalized with various N-chloramines in killing bacteria was compared among themselves with that of small organic molecules and spherical particles to investigate the effect of the surface charge, chemical structure, and shape of the particles. Results demonstrated that quaternary ammonium salt or amine functions in the chemical structure enhanced the antimicrobial activity of the particles and made the particles more effective than the small molecules in the presence of biological medium. The importance of particle shape in the killing tests was also confirmed.

A new route for the preparation of stable and water-dispersible coreshell g-Fe 2 O 3 /polymer MNPs has been developed in order to ensure a selective and covalent immobilization of biomolecules using maleimide-thiol coupling chemistry. A high maleimide functionalization was achieved by the grafting of dendritic coupling agent via a convergent approach.The integration of chemistry and nanotechnology in the eld of molecular biology has resulted in a new emerging research area, which offers exciting opportunities for discovering new materials, processes, and phenomena.1-4 In the last two decades, tremendous progress has been made in the development of magnetic particles on both synthetic and technological aspects.2-7 Due to the simplicity in their use and their large surface-to-volume ratio, magnetic particles are nowadays the most common solid platform for immobilization and detection of biomolecules.8-12 Among the major advances, important efforts have been dedicated to the development of highly functionalized magnetic nanoparticles (MNPs) for the immobilization of biomolecules. 8,9In this context, one of the major focuses is to design MNPs, which would covalently bind biomolecules without disrupting their biological activity, and concomitantly limit nonspecic adsorption. Nevertheless it is obvious that the amount of covalently immobilized biomolecules is limited by the number of available functional groups at the MNP surface. Therefore, in this work we aimed to ensure a high number of functional groups at the MNP surface by its functionalization with dendritic coupling agent. The efficiency of this approach was demonstrated in our previous results, which showed an increase of the surface functionalization 13-15 together with a dendritic effect on the intrinsic physico-chemical properties of the materials.16 In this study, the maleimide functional group was chosen for its biocompatibility and for its high selectivity towards thiol group of cysteine residue, naturally present or articially introduced in biomolecules. [17][18][19][20] In this context, maleimide functionalization of nanoparticles surfaces is one of the well-studied strategies for bioconjugation of nanoparticles. [21][22][23] Taking into account that the number of cysteine residues naturally present in biomolecules is very scarce (in comparison with other functionalities as amino or carboxyl groups), the maleimide-thiol coupling chemistry enables a degree of control over biomolecular orientation and at the same time requires no additional reagent and generates no byproducts (comparing to the EDC bioconjugate chemistry, for example). The Michael addition of thiol containing biomolecules to maleimide group is typically performed under mild conditions (in aqueous solutions or protic solvent at neutral pH and temperatures from 25 up to 37 C), resulting in the formation of a stable thioether linkage. 20The functionalization of MNPs with dendritic structures can be achieved either by a divergent approach for which the dendritic structure is built step by...

The covalent grafting on silica surfaces of a functional dendritic organosilane coupling agent inserted, in a long alkyl chain monolayer, is described. In this paper, we show that depending on experimental parameters, particularly the solvent, it is possible to obtain a nanodesigned surface via a bottom-up approach. Thus, we succeed in the formation of both homogeneous dense monolayer and a heterogeneous dense monolayer, the latter being characterized by a nanosized volcano-type pattern (4-6 nm of height, 100 nm of width, and around 3 volcanos/μm(2)) randomly distributed over the surface. The dendritic attribute of the grafted silylated coupling agent affords enough anchoring sites to immobilize covalently functional gold nanoparticles (GNPs), coated with amino PEG polymer to resolve the chemical nature of the surfaces and especially the volcano type nanopattern structures of the heterogeneous monolayer. Thus, the versatile surface chemistry developed herein is particularly challenging as the nanodesign is straightforward achieved in a bottom-up approach without any specific lithography device.