Self-assembling peptide-enriched electrospun polycaprolactone scaffolds promote the h-osteoblast adhesion and modulate differentiation-associated gene expression

Electrospun polycaprolactone (PCL) is able to support the adhesion and growth of h-osteoblasts and to delay their degradation rate to a greater extent with respect to other polyesters. The drawbacks linked to its employment in regenerative medicine arise fromits hydrophobic nature and the lack of biochemical signals linked to it. This work reports on the attempt to add five different self-assembling (SA) peptides to PCL solutions before electrospinning. The hybrid scaffolds obtained had regular fibers (SEM analysis) whose diameters were similar to those of the extracellularmatrix, more stable hydrophilic (contact angle measurement) surfaces, and anamorphous phase constrained by peptides (DSC analysis). They appeared to have a notable capacity to promote the h-osteoblast adhesion and differentiation process by increasing the gene expression of alkaline phosphatase, bone sialoprotein, and osteopontin. Adding an Arg-Gly-Asp (RGD) motif to a self-assembling sequence was found to enhance cell adhesion, while the same motif condensed with a scrambled sequence did not, indicating that there is a cooperative effect between RGD and 3D architecture created by the self-assembling peptides. The study demonstrates that self-assembling peptide scaffolds are still able to promote beneficial effects on h-osteoblasts even after they have been included in electrospun polycaprolactone. The possibility of linking biochemical messages to self-assembling peptides could lead the way to a 3D decoration of fibrous scaffolds

Dye-Doped Polymeric Microplastics: Light Tools for Bioimaging in Test Organisms

Ecosystems around the world are experiencing a major environmental impact from microplastic particles (MPs 0.1 & mu;m-1 mm). Water, sediments, and aquatic biota show the widespread presence of this pollutant. However, MPs are rarely used in laboratory studies as they are scarcely available for purchase or expensive, especially if one wishes to trace the particle with a dye or fluorescent. Furthermore, existing preparation techniques have limited application in biological studies. In this work, we propose a new, easy, and cheap way to prepare fluorescent MPs. The protocol is based on the osmosis method in order to obtain spherical polymeric particles of P(S-co-MMA), with 0.7-9 micron diameter, made fluorescent because dye-doped with rhodamine B isothiocyanate (RITC) or fluorescein isothiocyanate (FITC). The dye loading was studied and optimized, and the MPs-dye conjugates were characterized by UV-vis FTIR and XPS spectrometry and scanning electron microscopy (SEM). Furthermore, preliminary tests on aquatic organisms demonstrated the possible use of these fluorescent MPs in bioimaging studies, showing their absorption/adsorption by duckweeds (Lemna minuta) and insect larvae (Cataclysta lemnata)

Exploring the Antitumor Potential of Copper Complexes Based on Ester Derivatives of Bis(pyrazol-1-yl)acetate Ligands

Bis(pyrazol-1-yl)acetic acid (HC(pz)(2)COOH) and bis(3,5-dimethyl-pyrazol-1-yl)acetic acid (HC(pz(Me2))(2)COOH) were converted into the methyl ester derivatives 1 (L-OMe) and 2 (L-2OMe), respectively, and were used for the preparation of Cu(I) and Cu(II) complexes 3-10. The copper(II) complexes were prepared by the reaction of CuCl2 center dot 2H(2)O or CuBr2 with ligands 1 and 2 in methanol solution. The copper(I) complexes were prepared by the reaction of Cu[(CH3CN)(4)]PF6 and 1,3,5-triaza-7-phosphaadamantane (PTA) or triphenylphosphine with L-OMe and L-2OMe in acetonitrile solution. Synchrotron radiation-based complementary techniques (XPS, NEXAFS, and XAS) were used to investigate the electronic and molecular structures of the complexes and the local structure around copper ions in selected Cu(I) and Cu(II) coordination compounds. All Cu(I) and Cu(II) complexes showed a significant in vitro antitumor activity, proving to be more effective than the reference drug cisplatin in a panel of human cancer cell lines, and were able to overcome cisplatin resistance. Noticeably, Cu complexes appeared much more effective than cisplatin in 3D spheroid cultures. Mechanistic studies revealed that the antitumor potential did not correlate with cellular accumulation but was consistent with intracellular targeting of PDI, ER stress, and paraptotic cell death induction

Facile and selective covalent grafting of an RGD-peptide to electrospun scaffolds improves HUVEC adhesion

The development of a biomimetic surface able to promote endothelialization is fundamental in the search for blood vessel substitutes that prevent the formation of thrombi or hyperplasia. This study aims at investigating the effect of functionalization of poly-ε-caprolactone or poly(L-lactic acid-co-ɛ-caprolactone) electrospun scaffolds with a photoreactive adhesive peptide. The designed peptide sequence contains four Gly-Arg-Gly-Asp-Ser-Pro motifs per chain and a p-azido-Phe residue at each terminus. Different peptide densities on the scaffold surface were obtained by simply modifying the peptide concentration used in pretreatment of the scaffold before UV irradiation. Scaffolds of poly-ε-caprolactone embeddedwith adhesive peptideswere produced to assess the importance of peptide covalent grafting. Our results show that the scaffolds functionalized with photoreactive peptides enhance adhesion at 24h with a dosedependent effect and control the proliferation of human umbilical vein endothelial cells, whereas the inclusion of adhesive peptide in the electrospun matrices by embedding does not give satisfactory results

The reaction between Pt- and Pd- cis di-chloro complexes and 4,4’-diethynylbiphenyl: synthesis and characterization of a “zig-zag” metal/poly-yne polymer

The synthesis of poly-yne polymers containing transition metals inserted in the main chain has been attempted by reacting a dialkyne molecule, 4,4'-diethynylbiphenyl (or DEBP), with [PtCl2(dppe)] and [PdCl2(dppe)], the platinum- and palladium-cis square-planar dichlorine complexes containing diphenylphosphine ethane (dppe) as bidentate ligand. The aim of this work was to obtain organometallic polymers ([Pt(dppe)DEBP](n) and [Pd(dppe)DEBP](n), respectively) having an all-cis 'zigzag' structure, by formation of a sigma -acetylide bond between the transition metal complexes and the dialkyne molecule. When [PtCl2(dppe)] was reacted with DEBP, the formation of a chlorine-terminated [Pt(dppe)DEBP], oligomer was evidenced in the reaction involving the Pd(II) complex, on the other hand, [PdCl2(dppe)] seems to catalyse the polymerisation of DEBP via opening of the triple bond, producing a poly-DEBP polymer containing Pd(II) atoms inserted in the main chain

Chemical interaction at the Cu/ PPA interface: an X-ray photoemission investigation

A coverage-dependent XPS investigation of the early stages of interaction between evaporated Cu and polyphenylacetylene (PPA) has been carried out. Copper films have been deposited at 300 K to a final thickness of about 5 monolayers. Overlayer and substrate core-level emission behaviour indicates the layer-by-layer growth of Cu on the PPA surface without interdiffusion. At low copper coverages a chemical interaction between the Cu adatoms and the substrate is observed by monitoring the changes occurring at the pi --> pi * satellite feature of the C1s core-level line. We observe a decrease of intensity for this satellite as the copper coverage increases, interpreted in terms of the formation of a Cu-pi complex with the phenyl ring. The Cu Auger spectra demonstrate the presence of positively charged metal atoms up to a coverage of approximately 5 angstrom. In the submonolayer region the occurrence of broadening of the C1s core level on the low binding energy side is observed together with a positive shift for the Cu2p3/2 emission. Upon completion of the first copper monolayer these phenomena are removed. The observed behaviour can be accounted for in terms of differential charging with injection and trapping of charge into the PPA film from the Cu atoms that have not yet completed the first monolayer

Poly(N,N-dimethylpropargylamine): a pi-conjugated polymer as macromolecular ligand

The reaction between N, N-dimethylpropargylamine (DMPA) and a Ni(II) complex Ni(NCS)(2)(PPh(3))(2), leads to the formation of a pi-conjugated polymer (PDMPA) and to the interaction of the nickel atom of the complex with the nitrogen atoms of the pendent groups; a polymer-metal complex, PDMPA-Ni(II), is obtained. Reactions have been carried out using various complex/monomer molar ratios: the yield of the reaction and the nickel content of the polymer-metal complexes increase by increasing the amount of Ni(NCS)(2)(PPh(3))(2). Reactions of DMPA with a Rh(I) complex have also been studied for comparison; this catalyst induces only the linear polymerization of the monomer. The structure of PDMPA and of its complexes with Ni(II) has been studied by means of infra-red, nuclear magnetic resonance and X-ray photoelectron spectroscopies; a change in the stereochemistry of nickel, passing from Ni(NCS)(2)(PPh(3))(2) to the PDMPA-Ni(II) complexes, has been demonstrated

Evidence for different equilibrium regimes in poly(phenylacetylene)-iodine solutions by means of low-frequency electrical conductivity measurements

The electrical conductivity of poly( phenylacetylene)-iodine in tetrahydrofuran solutions has been measured at the frequency of 10 kHz, at different polymer concentrations in the presence of different amounts of iodine up to a concentration of 20 mg ml(-1). The data have been analysed in the light of current theories of polyelectrolyte solutions, considering the effect of counterions along the charged polymer chain. The dependence of the electrical conductivity on the iodine concentration suggests that the conduction mechanism is governed by different equilibria, resulting in two different charge-transfer complexes, PPA(+)I(5)(-) and PPA(+)I(3)(-); both of them can give rise to ion fluctuation