Novel Insight into the Photophysical Properties and 2D Supramolecular Organization of Poly(3,4-ethylenedioxythiophene)/Permodified Cyclodextrins Polyrotaxanes at the Air-Water Interface.

Two poly(3,4-ethylenedioxythiophene) polyrotaxanes (PEDOT∙TMe-ßCD and PEDOT∙TMe-γCD) end-capped by pyrene (Py) were synthesized by oxidative polymerization of EDOT encapsulated into TMe-ßCD or TMe-γCD cavities with iron (III) chloride (FeCl3) in water and chemically characterized. The effect of TMe-ßCD or TMe-γCD encapsulation of PEDOT backbones on the molecular weight, thermal stability, and solubility were investigated in depth. UV-vis absorption, fluorescence (FL), phosphorescence (PH), quantum efficiencies, and lifetimes in water and acetonitrile were also explored, together with their surface morphology and electrical properties. Furthermore, dynamic light scattering was used to study the hydrodynamic diameter (DH) and z-potential (ZP-ζ) of the water soluble fractions of PEDOT∙TMe-ßCD and PEDOT∙TMe-γCD. PEDOT∙TMe-ßCD and PEDOT∙TMe-γCD exhibited a sharp monodisperse peak with a DH of 55 ± 15 nm and 122 ± 32 nm, respectively. The ZP-ζ value decreased from -31.23 mV for PEDOT∙TMe-ßCD to -20.38 mV for PEDOT∙TMe-γCD, indicating that a negatively charged layer covers their surfaces. Surface pressure-area isotherms and Brewster angle microscopy (BAM) studies revealed the capability of the investigated compounds to organize into sizeable and homogeneous 2D supramolecular assemblies at the air-water interface. The control of the 2D monolayer organization through the thermodynamic parameters of PEDOT∙TMe-ßCD and PEDOT∙TMe-γCD suggests potential for a wide range of optoelectronic applications.

Photoluminescence of Argan-Waste-Derived Carbon Nanodots Embedded in Polymer Matrices.

In this work, photoluminescent (PL) carbon nano dots (CNDs) prepared from argan waste were embedded in highly optical transparent poly(styrene-co-acrylonitrile) (PSA) and cyclo-olefin copolymer (COC) matrices, which were further processed into thin films. In the first step, the luminescent CNDs were prepared through thermal processing of fine-groundargan waste, followed, in the second step, by direct dispersion in the polymer solutions, obtained by solving PSA and COC in selected solvents. These two polymer matrices were selected due to their high optical transparency, resilience to various environmental factors, and ability to be processed as quality thin films. The structural configuration of the CNDs was investigated through EDX, XPS, and FTIR, while DLS, HR-SEM, and STEM were used for their morphology investigation. The luminescence of the prepared CNDs and resulted polymer nanocomposites was thoroughly investigated through steady-state, absolute PLQY, and lifetime fluorescence. The quality of the resulted CND-polymer nanocomposite thin films was evaluated through AFM. The prepared highly luminescent thin films with a PL conversion efficiency of 30% are intended to be applied as outer photonic conversion layers on solar PV cells for increasing their conversion efficiency through valorization of the UV component of the solar radiation.

Intense Blue Photo Emissive Carbon Dots Prepared through Pyrolytic Processing of Ligno-Cellulosic Wastes.

In this work, Carbon Dots with intense blue photo-luminescent emission were prepared through a pyrolytic processing of forestry ligno-cellulosic waste. The preparation path is simple and straightforward, mainly consisting of drying and fine grinding of the ligno-cellulosic waste followed by thermal exposure and dispersion in water. The prepared Carbon Dots presented characteristic excitation wavelength dependent emission peaks ranging within 438-473 nm and a remarkable 28% quantum yield achieved at 350 nm excitation wavelength. Morpho-structural investigations of the prepared Carbon Dots were performed through EDX, FT-IR, Raman, DLS, XRD, and HR-SEM while absolute PLQY, steady state, and lifetime fluorescence were used to highlight their luminescence properties. Due to the wide availability of this type of ligno-cellulosic waste, an easy processing procedure achieved photo-luminescent properties, and the prepared Carbon Dots could be an interesting approach for various applications ranging from sensors, contrast agents for biology investigations, to photonic conversion mediums in various optoelectronic devices. Additionally, their biocompatibility and waste valorization in new materials might be equally good arguments in their favor, bringing a truly "green" approach.

Synergistic Effect of Low Molecular Weight Polyethylenimine and Polyethylene Glycol Components in Dynamic Nonviral Vector Structure, Toxicity, and Transfection Efficiency.

When studying polyethylenimine derivatives as nonviral vectors for gene delivery, among the important issues to be addressed are high toxicity, low transfection efficiency, and nucleic acid polyplex condensation. The molecular weight of polyethylenimine, PEGylation, biocompatibility and, also, supramolecular structure of potential carrier can all influence the nucleic acid condensation behavior, polyplex size, and transfection efficiency. The main challenge in building an efficient carrier is to find a correlation between the constituent components, as well as the synergy between them, to transport and to release, in a specific manner, different molecules of interest. In the present study, we investigated the synergy between components in dynamic combinatorial frameworks formed by connecting PEGylated squalene, poly-(ethyleneglycol)-bis(3-aminopropyl) and low molecular weight polyethylenimine components to 1,3,5-benzenetrialdehyde, via reversible imine bond, applying a dynamic combinatorial chemistry approach. We report comparative structural and morphological data, DNA binding affinity, toxicity and transfection efficiency concerning the ratio of polyethylenimine and presence or absence of poly-(ethyleneglycol)-bis(3-aminopropyl) in composition of dynamic combinatorial frameworks. In vitro biological assessments have revealed the fact that nonviral vectors containing poly-(ethyleneglycol)-bis(3-aminopropyl) and the lowest amount of polyethylenimine have significant transfection efficiency at N/P 50 ratio and display insignificant cytotoxicity on the HeLa cell line.

Dynameric Frameworks for DNA Transfection.

The design of performant nonviral vectors for efficient cellular DNA uptake represents a grand challenge. The variability of DNA targets and of the transfected cells limits the discovery of highly active nonviral vectors. Dynamic constitutional strategy presented here, combining easy synthesis and rapid screening, enables the selection of dynameric frameworks, DFs, for DNA transfection. On the basis of reversible recombination of cationic heads and of hydrophilic/hydrophobic network-constitutive building blocks, the multivalent core-shell dendritic architectures with an optimal diameter of 100 nm may be adaptively generated in the presence of DNA targets. The fittest DFs simultaneously exhibit optimal DNA binding, superior transfection yield to standard transfection SuperFect agent and preserve high HEK 293T cell viability. The present results constitutes an important advancement toward novel biologically friendly, low-cost, and efficient nonviral vectors.

Hybrid fullerene conjugates as vectors for DNA cell-delivery.

The present study reports fullerene conjugates that act as efficient binders of double stranded DNA (dsDNA) into cytofriendly polyplexes. The conjugates are designed to generate dendrimeric structures, having C60 as the core and bearing linear or branched PEI and polyethyleneglycol (PEG) arms (∼2 kDa). Simple and reproducible synthesis pathways provided C60-PEI and C60-PEG-PEI conjugates. They were able to bind linear and plasmidic dsDNA and they form particulate polyplexes of 50 to 200 nm in diameter. The resulted polyplexes toggle between the anionic and cationic state at nitrogen to phosphorous ratios (N/P) of about 5, as revealed by their zeta potential and became colloidally stable at N/P ratios above 10, as determined by atomic force microscopy (AFM). They are electrophoretically unbreakable starting with N/P ratios of 3 and of 5 when salmon sperm DNA and pEYFP-C1 plasmid, respectively are loaded. Both C60-PEI·pEYFP and C60-PEG-PEI·pEYFP polyplexes are non-cytotoxic against HEK 293T cells in culture and exhibit transfection efficiency better than 25% (N/P ratios above 20) and 6% (N/P ratios above 60) respectively, measured by flow cytometry. For comparison, the commercial SuperFect® from Qiagen (positive control) was able to provide an efficiency of 15-20%, under similar conditions. Moreover, the C60-PEG-PEI conjugate is as performant as the positive control in terms of expression of EYFP reporter gene in cultured cells and exhibited high cytocompatibility, determining cell proliferation up to 200%. Our study proved that C60-PEG-PEI is effective vector for DNA delivery being, in addition, easily synthesizable, practically non-cytotoxic and as efficient the commercially available transfection tools.

Polysiloxane ionic liquids as good solvents for ß-cyclodextrin-polydimethylsiloxane polyrotaxane structures.

An ionic liquid based on polydimethylsiloxane with imidazolium salt brushes was synthesized as a good solvent for ß-cyclodextrin-polydimethylsiloxane rotaxane. As expected the PDMS-Im/Br ionic liquid had a liquid-like non-Newtonian behavior with rheological parameters dependent on frequency and temperature. The addition of rotaxane to the ionic liquid strengthened the non-Newtonian character of the sample and a type of stable liquid-like network was formed due to the contribution of weak ionic interactions. The structure is stable in the 20 to 80 °C domain as proved by the oscillatory and rotational rheological tests.