Plankton is made of microscopic organisms living in salty or fresh waterish environments. Among these, shelled diatoms microalgae are capable to biomineralize inorganic silicate salts to produce nanostructured silica skeletons known as frustules. Diatom frustules are attractive for material scientists due to their possibility to be used as micro/nano structures useful for building up smart functional nanomaterials. Contrary to industrial silica, biosilica is produced at mild natural conditions. Here we present works about green extraction of biosilica from centric diatom species, chemically decorated with the antioxidant TEMPO radical trap, and used for bursting bone cells growth. Near this, we demonstrated that an in vivo functionalization of diatom biosilica with a bisphosphonate compound, sodium alendronate, leads to a final in vivo decorated and extracted material which exhibited the property of induction of osteoblasts activity and inhibition of osteoclasts proliferation.
Photosynthetic microorganisms and their Reaction Center (RC) photoenzymes can be used as active materials for bio-optoelectronic applications. Here we report approaches to interface RC molecules extracted from Rhodobacter sphaeroides with electrodes aiming to integrate the RC in electronic and electrochemical devices. Covalent binding with molecular semiconductors or supramolecular organization based on selective interactions have been explored. Alternatively, entrapment of the RC in biocompatible polymers is a convenient approach. These soft structures include polydopamine-based films or polydopamine/ethylenediamine nanoparticles capable of confining and protecting the RC, while improving RC-electrode charge transfer. We also describe the use of these polymers to address living photosynthetic bacterial cells on electrodes.
Diatoms are microalgae which have their unique cell encased into a nanostructured silica shell called frustule. The silica shells of diatoms can be envisioned as micro/nano structures suitable to further chemical modification yielding smart functional nanomaterials. Differently from the chemical production of silica, the biosynthesis of natural SiO2 occurs in mild conditions and it does not require the use of toxic precursors or reagents. Biosilica from diatoms features interesting properties such as high surface area, mechanical resistance and nanotexturization, which makes it appealing for applications in photonics, sensing, optoelectronics, biomaterial science and biomedicine. In addition, frustules’ biosilica can be easily chemically modified to add new functions. This can be done by simple surface functionalization, and/or in vivo by adding specific molecules to the culture medium. We have shown applications of chemically modified frustules for bone cells growth. In particular, we have demonstrated that in vivo functionalization of diatom biosilica with sodium alendronate results in osteoactive material. We have also demonstrated the production of functional structures by coating living diatoms with biomimetic organic polymers, like polydopamine (PDA). The resulting living heterostructures turn out to be intriguing platforms for additional chemical modifications, such as anchoring enzymes, affording multifunctional materials for biological applications. Finally, we have also shown that photonic microstructures can be produced by in vivo incorporation of tailored light emitting molecules in living Thalassiosira weissflogii diatoms. With a similar approach, biosilica has been doped with phosphorescent Ir complexes. Overall, our studies point out intriguing biotechnological routes to multifunctional nanomaterials for biomedicine and nanotechnology starting from unicellular algae.
Diatom microalgae represent the most abundant source of mesoporous biosilica in our planet. Their fossil derivative, diatomaceous earth (DE), consisting of diverse algal debris with nanostructured morphologies, is envisaged as a low cost silica support for biological applications. Intriguing features such as high surface/volume ratio and biocompatibility as well as unique absorption and confinement properties, make DE a suitable mesoporous support for biomolecules’ immobilization and stabilization. In this work, the model enzyme laccase was immobilized on DE using a polydopamine (PDA) coating that entraps a layer of protein molecules weakly interacting with DE. The DE/PDA/Laccase material, produced in aqueous solution under mild environment-friendly conditions, was characterized by spectroscopy and microscopy. The kinetic parameters and the recycle of the laccase were evaluated. This new hybrid material is in principle suitable for biomedical applications and for bioremediation in different environments.
Photosynthetic Reaction Center (RC) is a transmembrane photoenzyme capable of converting absorbed photons into electron-hole pairs with almost unitary efficiency. The unique properties of this natural photoconverter attract considerable interest for its use as functional component in nanomaterials and bioelectronics devices. Implementation of RC into nanostructures or anchoring on devices’ electrode surfaces require the development of suitable chemical manipulation. Here we report our methods to embed this protein in soft nanostructures or to covalently attach it on surfaces without denaturating it or altering its chemical properties.
KEYWORDS: Sensors, Molecules, Thin films, Transistors, Biological research, Biological and chemical sensing, Chemical analysis, Organic semiconductors, Active remote sensing, Chemical detection
Organic thin film transistor (OTFT) sensors are capable of fast, sensitive and reliable detection of
a variety of analytes. They have been successfully tested towards many chemical and biological
"odor" molecules showing high selectivity, and displaying the additional advantage of being
compatible with plastic technologies. Their versatility is based on the possibility to control the
device properties, from molecular design up to device architecture. Here phenylene-thiophene
based organic semiconductors functionalized with ad hoc chosen side groups are used as active
layers in sensing OTFTs. These materials, indeed, combine the detection capability of organic
molecules (particularly in the case of bio-substituted systems) with the electronic properties of
the conjugated backbone. A new OTFT structure including Langmuir-Schäfer layer by layer
organic thin films is here proposed to perform chemical detection of organic vapors, including
vapor phase chiral molecules such as citronellol vapors, with a detection limit in the ppm range.
Thermally evaporated α6T based OTFT sensors are used as well to be employed as standard
system in order to compare sensors performances.
A poly(phenyleneethynylene) polymer bearing amino acid pendant groups is used as enantioselective active layer in solid-state sensing devices. The chiral analyte in the present study is menthol in both the natural (-) and synthetic (+) enantiomers. The polymer bearing amino acid chiral sites is demonstrated to interact more favorably with the natural menthol than the synthetic one in a quartz crystal microbalance revealing system. Promising perspectives are seen for the use of such polymers in chiral discriminating, chemically sensitive resistors or even transistors.
Organic Thin Film Transistors (OTFTs) have been fabricated, in a standard bottom gate configuration, with Langmuir-Schafer (LS) or cast thin films of regioregular poly[1,4-(2,5-dioctyloxyphenylene)-2,5-thiophene], synthesized via an organometallic protocol, as active layers. The transistors electrical characterization has evidenced that LS based devices exhibit better performance level than cast film ones. Appealing perspectives for newly substituted conjugated polymers in OTFT sensing devices are discussed.
A series of copoly(2,3,5,6-tetrafluoro-1,4-phenylenevinylene-2,5-dioctyl oxy-1,4-phenylenevinylene)s containing variable ratios of tetrafluorophenylenevinylene and dialkoxyphenylenevinylene repeating units has been synthesized via the Stille cross-coupling reaction in order to investigate the influence on the (chi) (3) of the simultaneous presence of electron-deficient and electron-rich aromatic monomers in the PPV backbone. Third-order nonlinear optical properties of the resulting materials have been studied in chloroform solutions at (lambda) =1064 nm using the picosecond Z-scan technique. The nonlinear refractive index has been found to be negative, strongly dependent on the copolymer composition, and as high as (-10+/- 2)x10-12cm2/W.
The influence of the chemical structure on the (chi) (3) of organic molecules has been selectively investigated in three poly(2,5-dialkoxy-1,4-phenylenevinylene) polymers. They have similar degrees of polymerization and polydispersity indexes and differ only for the structure of the side groups in the 2.5 positions of the phenylene rings, that are respectively C8 linear and C5 branched alkoxy chains and C12 bridged closed dialoxy chain. Z-scan measurements show that all the investigated substituted-PPVs exhibit a small Im (chi) (3) and a large, negative Re (chi) (3) at (lambda) =1064nm. The obtained results yield evidence of a considerable dependence of the third-order nonlinear optical properties on the steric effect of the substituents.
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