Spontaneous Coassembly of the Protein Terthiophene into Fluorescent Electroactive Microfibers in 2D and 3D Cell Cultures.

Protein-based microfibers are biomaterials of paramount importance in materials science, nanotechnology, and medicine. Here we describe the spontaneous in situ formation and secretion of nanostructured protein microfibers in 2D and 3D cell cultures of 3T3 fibroblasts and B104 neuroblastoma cells upon treatment with a micromolar solution of either unmodified terthiophene or terthiophene modified by mono-oxygenation (thiophene → thiophene -oxide) or dioxygenation (thiophene → thiophene ,-dioxide) of the inner ring. We demonstrate via metabolic cytotoxicity tests that modification to the -oxide leads to a severe drop in cell viability.

Human Serum Albumin-Oligothiophene Bioconjugate: A Phototheranostic Platform for Localized Killing of Cancer Cells by Precise Light Activation.

The electronic, optical, and redox properties of thiophene-based materials have made them pivotal in nanoscience and nanotechnology. However, the exploitation of oligothiophenes in photodynamic therapy is hindered by their intrinsic hydrophobicity that lowers their biocompatibility and availability in water environments. Here, we developed human serum albumin (HSA)-oligothiophene bioconjugates that afford the use of insoluble oligothiophenes in physiological environments.

In Vivo Bioengineering of Fluorescent Conductive Protein-Dye Microfibers.

Engineering protein-based biomaterials is extremely challenging in bioelectronics, medicine, and materials science, as mechanical, electrical, and optical properties need to be merged to biocompatibility and resistance to biodegradation. An effective strategy is the engineering of physiological processes in situ, by addition of new properties to endogenous components. Here we show that a green fluorescent semiconducting thiophene dye, DTTO, promotes, in vivo, the biogenesis of fluorescent conductive protein microfibers via metabolic pathways.

Enantiopure polythiophene nanoparticles. Chirality dependence of cellular uptake, intracellular distribution and antimicrobial activity.

The use of intrinsic chiral molecules opens the door to bio-imaging specific tools and to the development of target-therapy. In this work the synthesis and characterization of polythiophenes with alkyl side chains containing one or chiral carbon is reported. Enantiopure chiral nanoparticles ( or NPs) were prepared from the polymers by a reprecipitation method.

Poly(3-hexylthiophene) nanoparticles for biophotonics: study of the mutual interaction with living cells.

We report on the mutual interaction between poly(3-hexylthiophene) nanoparticles (P3HT-NPs) and human embryonic kidney (HEK-293) cells. P3HT-NPs, prepared in sterile conditions and efficiently uptaken within the live cells cytosol, show well-ordered morphology, high colloidal stability and excellent biocompatibility. Electrophysiology and calcium imaging experiments demonstrate that physiological functions of live cells are fully preserved in the presence of P3HT-NPs.

New biocompatible polymeric micelles designed for efficient intracellular uptake and delivery.

New amphiphilic block copolymers are easily synthesised by post-polymerisation modifications of poly(glycidyl methacrylate) chain derivatives. The obtained material, upon dispersion in water, is capable of self-assembling into robust micelles. These nanoparticles, which are also characterised by adaptable stability, were loaded with different thiophene based fluorophores.

Supramolecular oligothiophene microfibers spontaneously assembled on surfaces or coassembled with proteins inside live cells.

During the last few decades, multifunctional nano- and microfibers made of semiconducting π-conjugated oligomers and polymers have generated much interest because of a broad range of applications extending from sensing to bioelectronic devices and (opto)electronics. The simplest technique for the fabrication of these anisotropic supramolecular structures is to let the molecules do the work by spontaneous organization driven by the information encoded in their molecular structure. Oligothiophenes-semiconducting and fluorescent compounds that have been extensively investigated for applications in thin-film field-effect transistors and solar cells and to a lesser extent as dyes for fluorescent labeling of proteins, DNA, and live cells-are particularly suited as building blocks for supramolecular architectures because of the peculiar properties of the thiophene ring.

Biocompatible and biodegradable fluorescent microfibers physiologically secreted by live cells upon spontaneous uptake of thiophene fluorophore.

Live cells can form multifunctional and environmentally responsive multiscale assemblies of living and non-living components. We recently reported the results of a unique approach to introduce supplementary properties, fluorescence in particular, into fibrillar proteins produced by live fibroblasts and extruded into the ECM. In this work, we demonstrate that the physiological secretion of fluorescent nanostructured microfibers upon the spontaneous uptake of the appropriate fluorophore extends to living cells derived by different tissue contexts.

Physiological formation of fluorescent and conductive protein microfibers in live fibroblasts upon spontaneous uptake of biocompatible fluorophores.

We have recently reported initial results concerning an original approach to introduce additional properties into fibrillar proteins produced by live fibroblasts and extruded into the ECM. The key to such an approach was biocompatible, fluorescent and semiconducting synthetic molecules which penetrated spontaneously the cells and were progressively encompassed via non-bonding interactions during the self-assembly process of the proteins, without altering cell viability and reproducibility. In this paper we demonstrate that the intracellular secretion of fluorescent microfibers can be generalized to living primary and immortalized human/mouse fibroblasts.

Oligothiophenes as fluorescent markers for biological applications.

This paper summarizes some of our results on the application of oligothiophenes as fluorescent markers for biological studies. The oligomers of thiophene, widely known for their semiconductor properties in organic electronics, are also fluorescent compounds characterized by chemical and optical stability, high absorbance and quantum yield. Their fluorescent emission can be easily modulated via organic synthesis by changing the number of thiophene rings and the nature of side-chains.

pH controlled staining of CD4(+) and CD19(+) cells within functionalized microfluidic channel.

Herein proposed is a simple system to realize hands-free labeling and simultaneous detection of two human cell lines within a microfluidic device. This system was realized by novel covalent immobilization of pH-responsive poly(methacrylic acid) microgels onto the inner glass surface of an assembled polydimethylsiloxane/glass microfluidic channel. Afterwards, selected thiophene labeled monoclonal antibodies, specific for recognition of CD4 antigens on T helper/inducer cells and CD19 antigens on B lymphocytes cell lines, were encapsulated in their active state by the immobilized microgels.

Live-cell-permeant thiophene fluorophores and cell-mediated formation of fluorescent fibrils.

In our search for thiophene fluorophores that can overcome the limits of currently available organic dyes in live-cell staining, we synthesized biocompatible dithienothiophene-S,S-dioxide derivatives (DTTOs) that were spontaneously taken up by live mouse embryonic fibroblasts and HeLa cells. Upon treatment with DTTOs, the cells secreted nanostructured fluorescent fibrils, while cell viability remained unaltered. Comparison with the behavior of other cell-permeant, newly synthesized thiophene fluorophores showed that the formation of fluorescent fibrils was peculiar to DTTO dyes.

A successful chemical strategy to induce oligothiophene self-assembly into fibers with tunable shape and function.

Functional supramolecular architectures for bottom-up organic nano- and microtechnology are a high priority research topic. We discovered a new recognition algorithm, resulting from the combination of thioalkyl substituents and head-to-head regiochemistry of substitution, to induce the spontaneous self-assembly of sulfur overrich octathiophenes into supramolecular crystalline fibers combining high charge mobility and intense fluorescence. The fibers were grown on various types of surfaces either as superhelices or straight rods depending on molecular structure.

Bicolor electroluminescent pixels from single active molecular material.

We report on the fabrication of the first bicolor micropixelated OLED from a single molecular material using a single-step bottom up procedure. The implementation of a deposition technique, based on a spatial-switch and conformational-sensitive STD surface-tension-driven lithography, has allowed us to exploit the spontaneous supramolecular properties and the conformational flexibility of a conjugated thiophene-based material, 6-bis-(50-hexyl-[2, 20]bithiophen-5-yl)-3, 5-dimethyl-dithieno[3, 2-b; 20, 30-d]thiophene (DTT7Me). The existence of two regularly alternating emitting regions on a micrometer scale allows obtaining electroluminescent emission at two different wavelengths from a single material.

Self-complementary nucleoside-thiophene hybrid systems: synthesis and supramolecular organization.

Versatile synthetic methods towards a variety of thiophene-nucleobase hybrid systems are reported. Adenine- and thymine-based modified nucleosides characterized by a bithiophene unit linked to the C5' or C8 position through an ethylenamino or an ethylensulfanyl bridge were synthesized and successfully polymerized in the presence of FeCl(3) . The self-organization properties of the pure polymers as well as their mixtures - with complementary nucleobases - were investigated by means of optical microscopy and AFM in cast film showing complex supramolecular structures resulting from the interplay of multiple intermolecular interactions.

Microwave-assisted synthesis of thiophene fluorophores, labeling and multilabeling of monoclonal antibodies, and long lasting staining of fixed cells.

We report the expedient microwave-assisted synthesis of thiophene based 4-sulfo-2,3,5,6,-tetrafluorophenyl esters whose molecular structure was engineered to achieve blue to red bright fluorescence. The reactivity toward monoclonal antibodies of the newly synthesized fluorophores was analyzed in comparison with that of the corresponding N-succinimidyl esters. Single-fluorophore and multiple-fluorophore labeled antibodies were easily prepared with both types of esters.

Magnetic-fluorescent colloidal nanobeads: preparation and exploitation in cell separation experiments.

Nanostructures displaying fluorescence and magnetic properties at the same time are potentially useful for achieving simultaneous bio-separation and bio-sensing (e.g., magnetic separation coupled with multiplexing optical detection of different tumour cell populations).

Spectroscopic signatures for planar equilibrium geometries in methyl-substituted oligothiophenes.

In recent studies it was demonstrated that temperature-dependent optical spectroscopy is a valuable tool for revealing the differences in the geometries of flexible molecules like oligothiophenes (OTs) in the ground (S(0)) and first excited (S(1)) electronic states, by examining the symmetry relations between the absorption and emission spectra: while at low temperature the spectra show mirror symmetry, pointing to planar geometries in S(0) and S(1), the symmetry relation breaks down at ambient temperature due to thermal population of torsional modes. In the present joint spectroscopic and theoretical study, we demonstrate that this behavior is also observed for di- and tetramethyl-substituted OTs, suggesting an essentially planar equilibrium geometry not only in S(1) but also in S(0), despite the increasing sterical hindrance which is imposed by the substituents. This rather surprising result is rationalized by the softness of the carbon-sulfur bond, which is able to adapt to the geometrical constraints.

Self-organization, optical, and electrical properties of alpha-quinquethiophene-dinucleotide conjugates.

The synthesis and properties of (5')TA(3')-t5 (8a) and (5')CG(3')-t5 (8b) conjugates, in which the self-complementary dinucleotides TA and CG are covalently bound to the central ring of alpha-quinquethiophene (t5), are described. According to molecular mechanics calculations, the preferred conformation of both 8a and 8b is that with the dinucleotide folded over the planar t5 backbone, with the nucleobases facing t5 at stacking distance. The calculations show that the aggregation process of 8a and 8b is driven by a mix of nucleobase-thiophene interactions, hydrogen bonding between nucleobases (non Watson-Crick (W&C) in TA, and W&C in CG), van der Waals, and electrostatic interactions.

Alkylenesulfanyl-bridged bithienyl cores for simultaneous tuning of electronic, filming, and thermal properties of oligothiophenes.

DPY and DPE alkylenesulfanyl-bridged bithienyls were prepared by a highly effective ring-closing reaction via arylalkylsulfonium intermediate and used as inner cores in oligothiophenes. HOMO-LUMO energy levels, conformational flexibility, and intrinsic asymmetry of the cores are reflected in the electronic, film-forming, and thermal properties of the corresponding oligomers.

Multifunctional nanostructures based on inorganic nanoparticles and oligothiophenes and their exploitation for cellular studies.

The combination of materials that possess different properties (such as, for instance, fluorescence and magnetism) into one single object of nanoscale size represents an attractive challenge for biotechnology, especially for their potential relevance in biomedical applications. We report here the preparation of novel bifunctional conjugates based on the linkage of inorganic nanoparticles to organic oligothiophene fluorophores (OTFs). In comparison to the organic dyes commonly used in bioimaging and more similarly to colloidal quantum dots, OTFs have broad optical absorption spectra, and therefore OTF fluorophores emitting at different colors can be excited with a single excitation source, allowing for easier multiplexing analysis.

Polyvinyl-locked versus free quaterthiophene: effect of spatial constraints on the electronic properties of n-hexylquaterthiophene.

A soluble, low-weight fraction of poly(alpha-vinyl,omega-n-hexyl-quaterthiophene), PT4Hex, having n-hexylquaterthiophenes as side-chain groups, is prepared by free-radical polymerization of alpha-vinyl,omega-n-hexyl-quaterthiophene and the corresponding properties compared to those of free di-n-hexylquaterthiophene (T4Hex). Optical analysis (absorption and emission) and X-ray diffraction data indicate that in the polyvinyl-locked architecture the quaterthiophene pendants adopt a cofacial arrangement with a mutual distance close enough for pi-pi orbitals to overlap ( approximately 4 A). As a consequence of the close chain packing, a shift of the reduction potential of about 0.

Liquid-crystalline rigid-core semiconductor oligothiophenes: influence of molecular structure on phase behaviour and thin-film properties.

The design, synthesis and properties of liquid-crystalline semiconducting oligothiophenes containing dithienothiophene (DTT), benzothiadiazole (BTZ) and carbazole (CBZ) rigid cores are described. The effect of molecular structure (shape, size and substitution) on their thermal behaviour and electrical properties has been investigated. Polarised optical microscopy (POM) and differential scanning calorimetry (DSC) analyses have revealed highly ordered smectic mesophases for most of the newly synthesised compounds.