Chirality induction to achiral molecules by silica-coated chiral molecular assemblies.

Hybrid silica-organic nanohelices are used to organize a large variety of nonchiral small organic molecules or inorganic anions to nanometer-sized assemblies. Such chiral organization of achiral molecules induces chiroptical properties as detected by vibrational or electronic circular dichroism (CD), as well as from circularly polarized luminescence (CPL).

Optical Gain in Semiconducting Polymer Nano and Mesoparticles.

The presence of excited-states and charge-separated species was identified through UV and visible laser pump and visible/near-infrared probe femtosecond transient absorption spectroscopy in spin coated films of poly[-9″-heptadecanyl-2,7-carbazole--5,5-(4,7-di-2-thienyl-2',1',3'-benzothiadiazole)] (PCDTBT) nanoparticles and mesoparticles. Optical gain in the mesoparticle films is observed after excitation at both 400 and 610 nm. In the mesoparticle film, charge generation after UV excitation appears after around 50 ps, but little is observed after visible pump excitation.

Near perfect head-to-head selectivity on the supramolecular photocyclodimerisation of 2-anthracenecarboxylate with self-organised gemini surfactant bilayers.

Silicificated self-organised crystalline bilayers of gemini surfactants were used as reaction templates for the supramolecular regioselective [4+4] photocyclodimerisation of 2-anthracenecarboxylate in water. A near perfect head-to-head cyclodimer selectivity, up to 97% at room temperature, was achieved with accelerated rate.

Divanillin-Based Polyazomethines: Toward Biobased and Metal-Free π-Conjugated Polymers.

Divanillin was synthesized in high yield and purity using Laccase from . It was then polymerized with benzene-1,4-diamine and 2,7-diaminocarbazole to form polyazomethines. Polymerizations were performed under microwave irradiation and without transition-metal-based catalysts.

A Complex Interplay of Anionic Phospholipid Binding Regulates 3'-Phosphoinositide-Dependent-Kinase-1 Homodimer Activation.

3'-Phosphoinositide-dependent-Kinase-1 (PDK1) is a master regulator whereby its PI3-kinase-dependent dysregulation in human pathologies is well documented. Understanding the direct role for PtdIns(3,4,5)P and other anionic phospholipids in the regulation of PDK1 conformational dynamics and its downstream activation remains incomplete. Using advanced quantitative-time-resolved imaging (Fluorescence Lifetime Imaging and Fluorescence Correlation Spectroscopy) and molecular modelling, we show an interplay of antagonistic binding effects of PtdIns(3,4,5)P and other anionic phospholipids, regulating activated PDK1 homodimers.

Size-Dependent Photophysical Behavior of Low Bandgap Semiconducting Polymer Particles.

The photophysics of water and propan-1-ol suspensions of poly [N-9"-heptadecanyl-2,7-carbazole--5,5-(4,7-di-2-thienyl-2',1',3'- benzothiadiazole)] (PCDTBT) nanoparticles and mesoparticles has been studied by ultrafast spectroscopy. High molar mass polymer (HMM > 20 kg/mol) forms nanoparticles with around 50 nm diameter mini-emulsion post-polymerization, while low molar mass (LMM < 5 kg/mol) polymer prepared by dispersion polymerization results in particles with a diameter of almost one order of magnitude larger (450 ± 50 nm). In this study, the presence of excited-states and charge separated species was identified through UV pump and visible/near-infrared probe femtosecond transient absorption spectroscopy.

Emission-Color Control in Polymer Films by Memorized Fluorescence Solvatochromism in a New Class of Totally Organic Fluorescent Nanogel Particles.

In this work, a new class of totally organic fluorescent nanogel particles and their exceptionally specific behaviors based on their unique structures are introduced, which draws a sharp line from conventional fluorophore-doped and fluorophore-branched-type particles. The nanogel particles, the diameter of which could be controlled by adjusting reaction conditions, such as the solvent system, were spontaneously fabricated with a spherical shape by direct polymerization of non-heterocyclic aromatic compounds, such as 2,6-dihydroxyanthracene, 2,6-dihydroxynaphthalene, and 9,9-bis(4-hydroxyphenyl)fluorene with triazinane as the cross-linker. A fluorophoric moiety formed from a polymer main chain was realized in the particle, and consequently, the resultant content of the fluorophoric moiety was around 70-80 wt % per particle.

Production, purification and characterization of an elastin-like polypeptide containing the Ile-Lys-Val-Ala-Val (IKVAV) peptide for tissue engineering applications.

Elastin-like polypeptides (ELPs) are biocompatible-engineered polypeptides, with promising interest in tissue engineering due to their intrinsic biological and physical properties, and their ease of production. The IKVAV (Ile-Lys-Val-Ala-Val) laminin-1 sequence has been shown to sustain neuron attachment and growth. In this study, the IKVAV adhesion sequence, or a scrambled VKAIV sequence, were incorporated by genetic engineering in the structure of an ELP, expressed in Escherichia coli and purified.

Adsorption of Proteins on Dual Loaded Silica Nanocapsules.

The design of nanocarriers containing hydrophobic and hydrophilic compounds represents a powerful tool for cocktail delivery. Water-in-oil-in-water emulsions constitute an attractive approach, as they offer dual encapsulation and provide a template for the constitution of a capsule. A limitation in the preparation of nano double emulsions is their instability resulting from high curvature radii.

Versatile cross-linked fatty acid-based polycarbonate networks obtained by thiol-ene coupling reaction.

Bio-sourced polycarbonate networks have been synthesized from an alkene-functional fatty-acid based polycarbonate precursor. Cross-linked networks were created using the radical thiol-ene coupling reaction. The resulting polycarbonate materials exhibited versatile properties either influenced by the structure of the cross-linker or the cross-linker/olefin unit ratio.

Induced circular dichroism of monoatomic anions: silica-assisted the transfer of chiral environment from molecular assembled nanohelices to halide ions.

We demonstrate the first example of induced CD of monoatomic anions. This was detected using chirally-arranged molecular assemblies of non-chiral cationic gemini surfactants (16-2-16) with monoatomic anions stabilized with silica-coating. Furthermore, we have also achieved multi-step transfer of a chiral environment through an in situ chemical reaction via chiralized monoatomic anions.

Optically Active Polyoxometalate-Based Silica Nanohelices: Induced Chirality from Inorganic Nanohelices to Achiral POM Clusters.

In order to investigate the principle of chiral induction from nanometric silica helices to polyoxometalate (POM) clusters, a series of optically active silica POM-based nanohelices (NANOPOMs) have been prepared by electrostatic grafting and direct adsorption of α-Keggin polyoxometalate [α-PW O ] to well-defined left- and right-handed silica nanohelices. UV/Vis, Raman, DRIFT, TEM, HR-TEM, EDS and circular dichroism (CD) spectroscopy were used to characterize these NANOPOMs, and confirm the presence of POM clusters as well as their interactions with the helical support. The optical activity of the left-handed and right-handed NANOPOMs has been proven by CD spectroscopy.

Variance component analysis to assess protein quantification in biomarker discovery. Application to MALDI-TOF mass spectrometry.

Controlling the technological variability on an analytical chain is critical for biomarker discovery. The sources of technological variability should be modeled, which calls for specific experimental design, signal processing, and statistical analysis. Furthermore, with unbalanced data, the various components of variability cannot be estimated with the sequential or adjusted sums of squares of usual software programs.

Design and self-assembly of PBLG-b-ELP hybrid diblock copolymers based on synthetic and elastin-like polypeptides.

The precision synthesis and self-assembly of amphiphilic copolypeptides containing a recombinant elastin-like polypeptide (ELP) block used as a macroinitiator for the ring opening polymerization (ROP) of γ-benzyl-l-glutamate (γ-BLG NCA) are herein presented. The molecular weight of the resulting PBLG-b-ELP block copolypeptides was precisely controlled without the use of complex initiator or demanding experimental setup. Diblock copolypeptides were obtained with an excellent control of the polymerization highlighted by the dispersity below 1.

Tuning Thermoresponsive Properties of Cationic Elastin-like Polypeptides by Varying Counterions and Side-Chains.

We report the synthesis of methionine-containing recombinant elastin-like polypeptides (ELPs) of different lengths that contain periodically spaced methionine residues. These ELPs were chemoselectively alkylated at all methionine residues to give polycationic derivatives. Some of these samples were found to possess solubility transitions in water, where the temperature of these transitions varied with ELP concentration, nature of the methionine alkylating group, and nature of the sulfonium counterions.

Induction of Strong and Tunable Circularly Polarized Luminescence of Nonchiral, Nonmetal, Low-Molecular-Weight Fluorophores Using Chiral Nanotemplates.

A new strategy is described for generating strong circularly polarized luminescence with highly tunable emission bands through chiral induction in nonchiral, totally organic, low-molecular-weight fluorescent dyes by chiral nanotemplate systems. Our approach allows the first systematic investigation to clarify the correlation between the circular dichroism and circularly polarized luminescence intensities. As a result, a dilute solution system with the highest circularly polarized luminescence intensity achieved to date and a dissymmetry factor of over 0.

Selective Tuning of Elastin-like Polypeptide Properties via Methionine Oxidation.

We have designed and prepared a recombinant elastin-like polypeptide (ELP) containing precisely positioned methionine residues, and performed the selective and complete oxidation of its methionine thioether groups to both sulfoxide and sulfone derivatives. Since these oxidation reactions substantially increase methionine residue polarity, they were found to be a useful means to precisely adjust the temperature responsive behavior of ELPs in aqueous solutions. In particular, lower critical solution temperatures were found to be elevated in oxidized sample solutions, but were not eliminated.

Quantitative Side-Chain Modifications of Methionine-Containing Elastin-Like Polypeptides as a Versatile Tool to Tune Their Properties.

Tuning the lower critical solution temperature (LCST) of temperature-responsive recombinant elastin-like polypeptides has usually been achieved by designing different protein sequences, in terms of amino acid composition and length, implying tedious molecular cloning steps. In the present work, we have explored the chemoselective alkylation of methionine as an easy means to modify elastin repeat side chains and easily modulate the LCST of the polypeptides. Such a versatile synthetic method shall practically be exploited to modulate any properties of recombinant polymers.

Amphiphilic PEO-b-PBLG diblock and PBLG-b-PEO-b-PBLG triblock copolymer based nanoparticles: doxorubicin loading and in vitro evaluation.

Huisgen's 1,3-dipolar cycloaddition ("Click Chemestry") has been used to prepare amphiphilic PEO-b-PBLG diblock and PBLG-b-PEO-b-PBLG triblock copolymers as potential carriers of anticancer drugs. Spherical and flower shaped micelles (D ≈ 100 nm) were obtained from diblock and triblock copolymers respectively. DOX was effectively encapsulated up to 18 wt.