Thiolated Graphene Oxide Nanoribbons as Templates for Anchoring Gold Nanoparticles: Two-Dimensional Nanostructures for SERS.

Graphene oxide nanoribbons (GONRs), obtained from the oxidative unzipping of carbon nanotubes, have been investigated as building blocks towards reaching active platforms in surface-enhanced Raman scattering (SERS). The complete development of carbon nanomaterials is strongly related to the exploitation of their chemical versatility, so this work is focused on the positive effect that a specific chemical functionalization provides to the SERS effect when gold nanoparticles are used. The covalent derivatization of GONRs with terminal thiol groups boosts their interaction with different types of gold nanoparticles (namely, 'naked' or citrate-stabilized), and the resulting two-dimensional aggregates show an intense enhancement of the Raman scattering from the carbon nanostructures because of their two-dimensional extended aggregation pattern. The SERS effect has been corroborated by theoretical calculations and a conceptual proof of SERS-based sensing.

Perylene Derivatives As Useful SERRS Reporters, Including Multiplexing Analysis.

Five perylene bisimide (PBI) derivatives were designed and synthesized, on the basis of quantum-chemical calculations. The influence of halogen substituents on the shape and energy of the frontier orbitals and the Raman spectra were calculated, in the prospect use in surface-enhanced resonance Raman scattering (SERRS) studies. The corresponding experiments confirmed a very strong SERRS response in the presence of pristine (i.e., uncoated) gold nanoparticles. These spectra can be used for multiplexing measurements, namely measurements in which, by using a single laser excitation, one can recognize the simultaneous presence of several analytes.

Synthetic strategies towards ruthenium-porphyrin conjugates for anticancer activity.

The conjugation of porphyrins to metal fragments is a strategy for making new compounds that are expected to combine the phototoxicity and the tumour-localization properties of the porphyrin chromophore with the cytotoxicity of the metal fragment for additive antitumour effect. We report here the preparation of new classes of porphyrin-ruthenium conjugates with potential bio-medical applications. Ruthenium was chosen because several Ru compounds have shown promising anticancer activity. The conjugation with the porphyrin moiety was accomplished either through peripheral pyridyl rings (e.g.meso-4'-tetrapyridylporphyrin, 4'TPyP) or through bpy units (e.g.meso-(p-bpy-phenyl)porphyrins, bpy(n)-PPs, n = 1-4). The number of Ru fragments attached to the porphyrins ranges from 1 to 4 and the total charge of the conjugates from -4 to +8. Different types of peripheral fragments, both Ru(III) and Ru(II), have been used: in some cases they are structurally similar to established anticancer compounds. Examples are [Na](4)[4'TPyP{trans-RuCl(4)(dmso-S)}(4)] (2), that bears four NAMI-type Ru(III) fragments, or [4'TPyP{Ru([9]aneS3)(en)}(4)][CF(3)SO(3)](8) (3) and [bpy(4)-PP{Ru([9]aneS3)(dmso-S)}(4)][CF(3)SO(3)](8) (9) (en = ethane-1,2-diamine, [9]aneS3 = 1,4,7-trithiacyclononane) that have four half-sandwich Ru(II) compounds. The Ru fragments may either contain one or more labile ligands, such as in 2 or in 9, or be coordinatively saturated and substitutionally inert, such as in 3 or in [bpy(4)-PP{Ru([12]aneS4)}(4)][CF(3)SO(3)](8) (11) ([12]aneS4 = 1,4,7,10-tetrathiacyclododecane). Most of the ruthenium-porphyrin conjugates described in this work are soluble--at least moderately--in aqueous solution and are thus suitable for biological investigations, in particular for cytotoxicity and photo-cytotoxicity tests.