Said Jebors

Toxicity and biodistribution of para-sulfonato-calix[4]arene in mice

The acute in vivo toxicity of para-35S-sulfonato-calix[4]arene has been determined, with no toxicity for doses up to 100 mg kg−1. Biodistribution shows that the molecule is rapidly cleared in urine, that it does not accumulate in the liver and spleen, and is not observed in the brain.

A molecular turnstile in para-octanoyl calix[4]arene nanocapsules.

The thermal treatment of different inclusion complexes of para-octanoyl calix[4]arene leads to the formation of a guest-free van der Waals nanocapsular structure possessing a remarkable stability caused by the high mobility of alkanoyl arms.

Solid lipid nanoparticles (SLNs) derived from para-acyl-calix[9]-arene: preparation and stability

A study of the parameters relating to the preparation of para-acyl-calix[9]arene-based solid lipid nanoparticles (SLNs) has been undertaken. Dynamic light scattering and electron microscopy have shown that the particle size varies between 85 and 215 nm depending on the acyl chain length. Parameters, including the organic solvent, amphiphile concentration and the presence of a co-surfactant affect the size of the SLNs obtained significantly. In contrast, stirring speed and solution viscosity have no effect. The ionic strength of the suspension has been shown to affect SLN stability in a salt-dependent manner. Ultrasonic and ultraviolet and 80°C treatment of the SLN suspensions have no effect on the SLN stability. The SLNs are unstable with respect to freezing–defreezing cycles, but can be reconstituted using mono- or disaccharides as cryoprotectants. Importantly, the temporal stability of these suspensions in water has been shown to be superior to 6 months. With regard to protein interactions, no SLN aggregation was observed in the presence of human serum albumin, with formation of a monolayer of albumin on the surface of the SLNs. Encapsulation was shown using acridine as a fluorescent probe.

From protected trialkoxysilyl-peptide building blocks to bioorganic–silica hybrid materials

A straightforward method for the preparation of hybrid bioorganic-inorganic materials is reported. Common strategies to synthesize such promising materials require special surface modifications of silica followed by grafting of the organic moiety via chemoselective ligation. In this context, we set up a general and bottom-up strategy relying on modified peptides functionalized with a trialkoxysilane group. Used in mixtures with TEOS and a surfactant as the structure directing agent, these hybrid building blocks allow one step direct synthesis of bioorganic-inorganic hybrid materials. Two examples were chosen to demonstrate our general approach. (1) An antifouling surface was prepared by dip coating of a sol containing an antibacterial silylated peptide. (2) Organized mesoporous silica displaying a peptide catalyst in the pores was prepared in one step and tested.

Engineered Adhesion Peptides for Improved Silicon Adsorption

Engineering peptides that present selective recognition and high affinity for a material is a major challenge for assembly-driven elaboration of complex systems with wide applications in the field of biomaterials, hard-tissue regeneration, and functional materials for therapeutics. Peptide-material interactions are of vital importance in natural processes but less exploited for the design of novel systems for practical applications because of our poor understanding of mechanisms underlying these interactions. Here, we present an approach based on the synthesis of several truncated peptides issued from a silicon-specific peptide recovered via phage display technology. We use the photonic response provided by porous silicon microcavities to evaluate the binding efficiency of 14 different peptide derivatives. We identify and engineer a short peptide sequence (SLVSHMQT), revealing the highest affinity for p(+)-Si. The molecular recognition behavior of the obtained peptide fragment can be revealed through mutations allowing identification of the preferential affinity of certain amino acids toward silicon. These results constitute an advance in both the engineering of peptides that reveal recognition properties for silicon and the understanding of biomolecule-material interactions.

Simple and Specific Grafting of Antibacterial Peptides on Silicone Catheters

To fight against nosocomial infection initiated by colonization of medical devices, a strategy enabling the direct and fast functionalization of silicone surfaces is proposed. This strategy proceeds in a site-specific way using original hybrid silylated antibacterial peptides. This safe and up-scalable method guarantees a covalent and robust immobilization with the correct orientation of the bioactive moiety. Importantly it also avoids multi-step chemical modifications of the surface or multi-layer polymer coatings. As proof of concept, antibacterial silicone catheter has been prepared whose immediate and long term efficiency is superior by comparison to similar silver-embedded materials.

A New Way to Silicone‐Based Peptide Polymers

We describe a new class of silicone-containing peptide polymers obtained by a straightforward polymerization in water using tailored chlorodimethylsilyl peptide blocks as monomeric units. This general strategy is applicable to any type of peptide sequences, yielding linear or branched polymer chains composed of well-defined peptide sequences.

Bioorganic hybrid OMS by straightforward grafting of trialkoxysilyl peptides

A novel strategy for the synthesis of peptide-bioorganic hybrid silica materials is reported. It relies on the design of hybrid peptides bearing a trialkoxysilane group. These reactive monomers are covalently attached to silica without requiring any prior surface modification. As an example, a bioorganic-inorganic OMS aldolisation catalyst is prepared using the peptide sequence Pro-Pro-Asp-Lys.

Turning peptides in comb silicone polymers

We have recently reported on a new class of silicone–peptide‵ biopolymers obtained by polymerization of di‐functionalized chlorodimethylsilyl hybrid peptides. Herein, we describe a related strategy based on dichloromethylsilane‐derived peptides, which yield novel polymers with a polysiloxane backbone, comparable with a silicone‐bearing pendent peptide chains. Interestingly, polymerization is chemoselective toward amino acids side‐chains and proceeds in a single step in very mild conditions (neutral pH, water, and room temperature). As potential application, a cationic sequence was polymerized and used for antibacterial coating. Copyright

Site-specific grafting on titanium surfaces with hybrid temporin antibacterial peptides

Relying on a membrane-disturbing mechanism of action and not on any intracellular target, antimicrobial peptides (AMP) are attractive compounds to be grafted on the surface of implantable materials such as silicone catheters or titanium surgical implants. AMP sequences often display numerous reactive functions (e.g. amine, carboxylic acid) on their side chains and straightforward conjugation chemistries could lead to uncontrolled covalent grafting, random orientation, and non-homogenous density. To achieve an easy and site specific covalent attachment of unprotected peptides on titanium surfaces, we designed hybrid silylated biomolecules based on the temporin-SHa amphipathic helical antimicrobial sequence. With the grafting reaction being chemoselective, we designed five analogues displaying the silane anchoring function at the N-ter, C-ter or at different positions inside the sequence to get an accurate control of the orientation. Grafting density calculations were performed by XPS and the influence of the orientation of the peptide on the surface was clearly demonstrated by the measure of antimicrobial activity. Temporin amphipathic helices are described to permeabilize the bacterial membrane by interacting in a parallel orientation with it. Our results move in the direction of this mechanism as the selective grafting of hybrid temporin 2 through a lysine placed at the center of the peptide sequence, resulted in better biofilm growth inhibition of E. coli and S. epidermis than substrates in which temporins were grafted via their C- or N-terminus.