Clicked BODIPY-Fullerene-Peptide Assemblies: Studies of Electron Transfer Processes in Self-Assembled Monolayers on Gold Surfaces.

Two BODIPY-C-peptide assemblies were synthesized by CuAAC reactions of BODIPY-C dyads and a helical peptide functionalized with a terminal alkyne group and an azide group, respectively. The helical peptide within these assemblies was functionalized at its other end by a disulfide group, allowing formation of self-assembled monolayers (SAMs) on gold surfaces. Characterizations of these SAMs, as well as those of reference molecules (BODIPY-C-alkyl, C-peptide and BODIPY-peptide), were carried out by PM-IRRAS and cyclic voltammetry.

Photoinduced Electron Transfer and Energy Transfer Processes in a Flexible BODIPY-C Dyad.

A new donor-acceptor dyad composed of a BODIPY (4,4'-difluoro-4-bora-3a,4a-diaza--indacene) donor and a fullerene C acceptor has been synthesized and characterized. This derivative has been prepared using a clickable fullerene building block that bears an alkyne moiety and a maleimide unit. The post-functionalization of the maleimide group by a BODIPY thiol leads to a BODIPY-C dyad, leaving the alkyne moiety for further functional arrangement.

Photoactive Polyoxometalate/DASA Covalent Hybrids for Photopolymerization in the Visible Range.

The synthesis of TBA-DASA-POM-DASA, the first photoactive covalent hybrid polyoxometalate (POM) incorporating a donor-acceptor Stenhouse adduct (DASA) reverse photochrome, is presented. It has been evidenced that in solution the equilibrium between the colorless cyclopentenone and the highly colored triene conformers is strongly dependent not only on the nature of the solvent but also the countercations, allowing to tune its optical properties. This complex has been further associated to photochromic spironaphtoxazine cations, resulting in a material which can be activated by two distinct optical stimuli.

Sulfamide chemistry applied to the functionalization of self-assembled monolayers on gold surfaces.

Aniline-terminated self-assembled monolayers (SAMs) on gold surfaces have successfully reacted with ArSONHOSOAr (Ar = 4-MeCH or 4-FCH) resulting in monolayers with sulfamide moieties and different end groups. Moreover, the sulfamide groups on the SAMs can be hydrolyzed showing the partial regeneration of the aniline surface. SAMs were characterized by water contact angle (WCA) measurements, Fourier-transform infrared reflection absorption spectroscopy (IRRAS) and X-ray photoelectron spectroscopy (XPS).

Sequential Copper-Catalyzed Alkyne-Azide Cycloaddition and Thiol-Maleimide Addition for the Synthesis of Photo- and/or Electroactive Fullerodendrimers and Cysteine-Functionalized Fullerene Derivatives.

In this study, the functionalization of a fullerene building block in a stepwise process by means of the copper-catalyzed alkyne-azide cycloaddition (CuAAC) and thiol-maleimide reactions is reported. Grafting of the fullerene platform with a variety of azido derivatives, including Bodipy, pyrene and ferrocene, was carried out first. These fullerene compounds were then reacted with thiol derivatives to yield sophisticated structures comprising photo- and/or electroactive fullerodendrimers and cysteine-functionalized fullerene assemblies.

BSA adsorption on aliphatic and aromatic acid SAMs: investigating the effect of residual surface charge and sublayer nature.

In this work, the influence of surface charge and layer rigidity on Bovin Serum Albumin (BSA) adsorption has been investigated. To this aim, Self Assembled Monolayers (SAMs) bearing terminal COOH or COO(-) groups were built on gold surfaces. The rigidity of the acid terminated SAMs was modified using either an aliphatic, mercaptoundecanoic acid (MUA), or an aromatic, mercaptobenzoic acid (MBA) thiol.

The predominant role of collagen in the nucleation, growth, structure and orientation of bone apatite.

The involvement of collagen in bone biomineralization is commonly admitted, yet its role remains unclear. Here we show that type I collagen in vitro can initiate and orientate the growth of carbonated apatite mineral in the absence of any other vertebrate extracellular matrix molecules of calcifying tissues. We also show that the collagen matrix influences the structural characteristics on the atomic scale, and controls the size and the three-dimensional distribution of apatite at larger length scales.

Drastic Au(111) surface reconstruction upon insulin growth factor tripeptide adsorption.

Adsorption of biomolecules at metal surfaces often creates two-dimensional ordering of the adlayers. However, metal substrate reconstruction is less commonly observed, unless upon annealing of the molecule-surface system. Here, we report on the drastic room-temperature reconstruction of the Au(111) surface, driven by the adsorption of insulin growth factor tripeptide molecules.

Modifying protein adsorption by layers of glutathione pre-adsorbed on Au(111).

Molecular interaction with metal surfaces raises fundamental questions regarding their binding tendency, their dispersion on the surface, as well as their conformation which may change their biological properties; addressing these questions, and being able to tune protein interactions, is of primary importance for the control of biointerfaces. In this study, one tripeptide, GSH (glu-cys-gly), was used to condition gold surfaces and thus influence the adsorption of bovine serum albumin (BSA). Depending on the pH value of the GSH solution, cationic, zwitterionic or anionic forms of the tripeptide could be stabilised on the surface, before interacting with BSA solutions.

Peptide interactions with metal and oxide surfaces.

Increasing interest in bio-interfaces for medical, diagnostic, or biotechnology applications has highlighted the critical scientific challenge behind both the understanding and control of protein-solid surface interactions. In this context, this Account focuses on the molecular-level characterization of the interactions of peptides, ranging in size from a few amino acids to long sequences, with metal and oxide surfaces. In this Account, we attempt to fill the gap between the well-known basic studies of the interaction of a single amino acid with well-defined metal surfaces and the investigations aimed at controlling biocompatibility or biofilm growth processes.

Tufted puffin reproduction reveals ocean climate variability.

Anomalously warm sea-surface temperatures (SSTs) are associated with interannual and decadal variability as well as with long-term climate changes indicative of global warming. Such oscillations could precipitate changes in a variety of oceanic processes to affect marine species worldwide. As global temperatures continue to rise, it will be critically important to be able to predict the effects of such changes on species' abundance, distribution, and ecological relationships so as to identify vulnerable populations.