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Microchannelled 3D architectures composed of multiwall carbon nanotubes (MWCNTs) surface decorated with Pt nanoparticles and chitosan (CHI) are prepared by an ice segregation induced self-assembly (ISISA) process. The microchannelled structures are highly porous (specific gravity ∼10-2) and exhibit excellent electron conductivity (2.5 S·cm-1) thanks to both the high content of MWCNTs (up to 89 wt %) and their interconnection. The Pt/MWCNT/CHI 3D architectures provide remarkable performance as anodes for a direct methanol fuel cell (DMFC).

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This work describes a simple synthetic route to induce chitosan (CHI) gelation by the in situ formation of gold nanoparticles (AuNPs). AuNPs were obtained by thermal treatment (e.g., 40 and 80 °C) of CHI aqueous solutions containing HAuCl(4) and in the absence of further reducing agents. The CHI hydrogels resulting after AuNP formation were submitted to unidirectional freezing and subsequent freeze-drying via ISISA (ice-segregation-induced self-assembly) process for the preparation of CHI scaffolds. The study of AuNP-CHI scaffolds by SEM and confocal fluorescence microscopy revealed a morphological structure characteristic of the hydrogel nature of the samples subjected to the ISISA process. Interestingly, not only the morphology but also the dissolution and swelling degree of the resulting CHI scaffolds were strongly influenced by the strength of the hydrogels obtained by the in situ formation of AuNP. We have also studied the catalytic activity AuNP-CHI scaffolds in the reduction of p-nitrophenol. The negligible dissolution and low swelling degree obtained in certain AuNP-CHI scaffolds allowed them to be used for more than four cycles with full preservation of the reaction kinetics.

Rhodamine B (RB) nanoparticles entrapped in hybrid glasses show enhanced fluorescent emission (approximately 220-fold larger than that of single RB molecules) thanks to the configuration control of the self-assembled aggregates that form the supramolecular architecture of the nanoparticles. The fluorescence performance reported in this work is around 1 order of magnitude larger than that recently reported for fluorescent Nile Red nanoparticles. The fluorescence enhancement results from the use of a highly efficient fluorescent dye such RB and the formation of larger nanoparticles. Note that the later implies the presence of a large number of emitting centers involved in the fluorescence emission.

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