Improving the In Vitro Removal of Indoxyl Sulfate and p-Cresyl Sulfate by Coating Diatomaceous Earth (DE) and Poly-vinyl-pyrrolidone-co-styrene (PVP-co-S) with Polydopamine

Polydopamine (PDA) is a synthetic eumelanin polymer mimicking the biopolymer secreted by mussels to attach to surfaces with a high binding strength. It exhibits unique adhesive properties and has recently attracted considerable interest as a multifunctional thin film coating. In this study, we demonstrate that a PDA coating on silica- and polymer-based materials improves the entrapment and retention of uremic toxins produced in specific diseases. The low-cost natural nanotextured fossil diatomaceous earth (DE), an abundant source of mesoporous silica, and polyvinylpyrrolidone-co-Styrene (PVP-co-S), a commercial absorbent comprising polymeric particles, were easily coated with a PDA layer by oxidative polymerization of dopamine at mild basic aqueous conditions. An in-depth chemical-physical investigation of both the resulting PDA-coated materials was performed by SEM, AFM, UV-visible, Raman spectroscopy and spectroscopic ellipsometry. Finally, the obtained hybrid systems were successfully tested for the removal of two uremic toxins (indoxyl sulfate and p-cresyl sulfate) directly from patients' sera.

Synthesis and Investigation of Electro-Optical Properties of H-Shape Dibenzofulvene Derivatives

We have synthetized two classes of dibenzofulvene-arylamino derivatives with an H-shape design, for a total of six different molecules. The molecular structures consist of two D-A-D units connected by a thiophene or bitiophene bridge, using diarylamino substituents as donor groups anchored to the 2,7- (Group A) and 3,6- (Group B) positions of the dibenzofulvene backbone. The donor units and the thiophene or bithiophene bridges were used as chemico-structural tools to modulate electro-optical and morphological-electrical properties. A combination of experiments, such as absorption measurements (UV-Vis spectroscopy), cyclic voltammetry, ellipsometry, Raman, atomic force microscopy, TD-DFT calculation and hole-mobility measurements, were carried out on the synthesized small organic molecules to investigate the differences between the two classes and therefore understand the relevance of the molecular design of the various properties. We found that the anchoring position on dibenzofulvene plays a crucial key for fine-tuning the optical, structural, and morphological properties of molecules. In particular, molecules with substituents in 2,7 positions (Group A) showed a lower structural disorder, a larger molecular planarity, and a lower roughness.

Regioregularity and deposition effect on the physical/chemical properties of polythiophene derivatives films

Polythiophene thin films are widely studied for applications in organic electronics. However, some comparisons are still missing, regarding distinct deposition techniques and regioregularity. Here regioregular and regiorandom alkyl-substituted polythiophene derivatives (P3ATs) were deposited on solid substrates using both Langmuir-Blodgett (LB) and Langmuir-Schaefer (LS) techniques. The main goal was to verify the possible influence of the regioregularity as well the deposition technique on their optical, electrical and electrochemical properties. LB and LS films of regioregular and regiorandom poly(3-butylthiophene) (P3BT) and poly(3-octylthiophene) (P3OT) were deposited onto glass/Indium-Tin-Oxide) substrates and characterized by UV-visible optical spectroscopy, atomic force microscopy, cyclic voltammetry, and conductivity measurements. The results demonstrated the influence of the deposition technique on the electrical outcome, moreover, the regioregularity affected all the performed characterizations. In addition, this paper may be useful to understand how the amphiphilic molecule addition affected the film properties of regioregular and regiorandom P3ATs, particularly the energy diagram provided by the electrochemical and absorption features.

How to Design Donor-Acceptor Based Heterocyclic Conjugated Polymers for Applications from Organic Electronics to Sensors

Over the past few years, significant progress has been made in the design of organic semi-conducting conjugated polymers that readily transport holes or electrons and can result in light emission. The conjugated backbone consist mainly of electron-donating (donor) and electron-withdrawing (acceptor) units as alternating groups in a conjugated oligomer or polymer that can be regulated by physical properties such as π conjugation length, monomer alteration, inter/intramolecular interactions and energy levels. Certainly, it is notable today that the highest occupied molecular orbital level of the producing material is localized predominantly on the electron-donating moiety and lowest unoccupied molecular orbital level on the electron-accepting moiety. Conjugated oligomers or polymers are used in many detecting fields due to their exceptional ability to sense toxic chemicals, metal ions and biomolecules. The conjugated polymers have unique delocalized π-electronic "molecular wires" that can expand the fluorescence intensity considerably. The fluorescence intensity of polymers can be quenched by particular quenching molecules. In this review, the fluorescence intensity, detecting of multiple metal ions, solubility, photochemical stability and optoelectronic properties of these conjugated polymers, and how they can be regulated by different functional groups, are discussed in detail.

Movement of new direction from conjugated polymer to semiconductor composite polymer nanofiber

In the past few years, there was a tremendous growth in conjugated polymer nanofibers via design of novel conjugated polymers with inorganic materials. Synthetic routes to these conjugated polymers involve new, mild polymerization techniques, which enable the formation of well-defined polymer architectures. This review provides interest in the development of novel (semi) conducting polymers, which combine both organic and inorganic blocks in one framework. Due to their ability to act as chemosensors or to detect various chemical species in environmental and biological systems, fluorescent conjugated polymers have gained great interest. Nanofibers of metal oxides and sulfides are particularly interesting in both their way of applications and fundamental research. These conjugated nanofibers operated for many applications in organic electronics, optoelectronics, and sensors. Synthesis of electrospun fibers by electrospinning technique discussed in this review is a simple method that forms conjugated polymer nanofibers. This review provides the basics of the technique and its recent advances in the formation of highly conducting and high-mobility polymer fibers towards their adoption in electronic application.

Carbon Nanohorns Modified with Conjugated Terthienyl/Terthiophene Structures: Additives to Enhance the Performance of Dye-Sensitized Solar Cells

A series of carbon nanohorns (CNHs) constituted by the aggregation of about 2000 individual conical graphene tubes (diameters from 2 nm to 5 nm and a length of 40-50 nm) that have been modified with dyes of two, three, or four terthienyl groups has been prepared by adsorbing the corresponding dye on the CNH. Persistent inks in o-dichlorobenzene (o-DCB) of these dye-CNH conjugates were obtained by laser irradiation of o-DCB suspensions of the dye-CNH solids. These inks were used in combination or not with N719 dye for the preparation of dye-sensitized solar cells (DSSC) of TiO₂. It was measured that the terthienyl dye with the largest conjugation deposited on the CNH additively increased the performance of an analogous TiO₂ cell from an efficiency of 4.07% to 6.24%. This result shows the potential of dye-modified CNHs as additives in the construction of more efficient DSSCs.

Design of Assembled Systems Based on Conjugated Polyphenylene Derivatives and Carbon Nanohorns

Promising materials have been designed and fully characterised by an effective interaction between versatile platforms such as carbon nanohorns (CNHs) and conjugated molecules based on thiophene derivatives. Easy and non-aggressive methods have been described for the synthesis and purification of the final systems. Oligothiophenephenylvinylene (OTP) systems with different geometries and electron density are coupled to the CNHs. A wide range of characterization techniques have been used to confirm the effective interaction between the donor (OTP) and the acceptor (CNH) systems. These hybrid materials show potential for integration into solar cell devices. Importantly, surface-enhanced Raman spectroscopy (SERS) effects are observed without the presence of any metal surface in the system. Theoretical calculations have been performed to study the optimised geometries of the noncovalent interaction between the surface and the organic molecule. The calculations allow information on the monoelectronic energies of HOMO-LUMO orbitals and band gap of different donor systems to be extracted.