Publications by authors named "Adriana Pietropaolo"

Every biological and physicochemical process occurring in a fluid phase depends on the diffusion coefficient (D) of the species in solution. In the present work, a model to describe and fit the behaviour of as a function of structure and extensive thermodynamics parameters in binary solutions of linear chain organic molecules is developed. Supporting experimental and computational evidences for this model are obtained by measuring for a series of -alcohols through a novel surface plasmon resonance method and molecular dynamics simulations.

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  • Two chiral derivatives of 1,10-phenanthroline, Men2Phen and MB2Phen, were synthesized, showcasing differences in their molecular structures.
  • The variations in rigidity and bulkiness of their chiral substituents resulted in distinct differences in their circular dichroism properties.
  • Men2Phen demonstrated strong circularly polarized luminescence in solid form, while MB2Phen exhibited very weak CPLm due to its amorphous nature and poor crystallization.
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  • Copper is vital for cellular processes but needs careful regulation to avoid toxicity, involving specific transport proteins like metallochaperones and ATPases.
  • The research utilized simulations based on free-energy perturbation and parallel bias metadynamics to understand the Cu(I) exchange between the copper chaperone Atox1 and its partner ATP7A, which is important for copper transport and preventing diseases like Menkes disease.
  • The study's findings showed that the dissociation of Atox1 and ATP7A's first domain (Mnk1) from the Cu(I) complex requires similar amounts of energy, indicating a stepwise mechanism of dissociation.
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  • Neurotrophins, important for the central nervous system development and functioning, face challenges in drug application due to instability and side effects.
  • This study focuses on a cyclic peptide, c-NGF(1-14), which mimics the neurotrophic growth factor and demonstrates a stable conformation that interacts effectively with the NGF receptor TrkA.
  • c-NGF(1-14) promotes PC12 cell differentiation and enhances biological activities when bound to copper, ultimately activating key signaling pathways that lead to the release of beneficial growth factors like BDNF and VEGF.
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  • Optically active poly(naphthalene-1,4-diyl) was synthesized using two methods: helix-sense-selective polymerization and circularly polarized light (CPL) irradiation, showcasing unique spectral characteristics.* -
  • The chirality in the polymer from helix-sense-selective polymerization comes from a preferred handedness in its helical structure, while the CPL-based polymer adopts a stable non-helical chiral form only in solid state.* -
  • Both types of polymers demonstrated strong circularly polarized luminescence, with the helix of the polymer from helix-sense-selective polymerization becoming less stable in certain solvents but stabilized in a mixed hexane-dichlorometh
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Optically active, hyperbranched, poly(fluorene-2,4,7-triylethene-1,2-diyl) [poly(fluorenevinylene)] derivatives bearing a neomenthyl group and a pentyl group at the 9-position of the fluorene backbone at various ratios acted as a chirality donor (host polymers) efficiently included naphthalene, anthracene, pyrene, 9-phenylanthracene, and 9,10-diphenyanthracene as a chirality acceptor (guest molecules) in their interior space in film as well as in solution, with the guest molecules exhibiting intense circular dichroism through chirality transfer with chirality amplification. The efficiency of the chirality transfer was much higher with higher-molar-mass polymers than lower-molar-mass ones as well as with hyperbranched polymers compared to the analogous linear ones. The hyperbranched polymers include the small molecules in their complex structure without any specific interactions at various stoichiometries.

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  • Chiral materials possess unique properties that allow them to absorb and emit circularly polarized light, making them important for various applications.
  • This tutorial focuses on using theoretical simulations to predict and interpret chiroptical data, such as circular dichroism (CD) and circular polarized luminescence (CPL).
  • We emphasize computational methods, including density functional theory (DFT) and its time-dependent extension (TD-DFT), to effectively study the photophysical characteristics and geometries of chiral materials.
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  • Brain-derived neurotrophic factor (BDNF) is crucial for brain development and functions, but its therapeutic use has been difficult, prompting research into peptide mimics of BDNF.
  • A new dimeric peptide based on the BDNF N-terminal region (d-bdnf) has been synthesized and shown to effectively stimulate the TrkB receptor, enhancing vital signaling pathways for neuronal growth.
  • Further studies revealed that d-bdnf supports neuron development and its activity is influenced by zinc ions, suggesting potential pathways for future BDNF-related therapies.
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An unprecedented non-uniform self-folding of artificial polymer chains composed of turn moieties and stretched segments is presented through the design of a set of optically active poly(fluorene-2,7-diylethene-1,2-diyl) (poly(fluorenevinylene)) derivatives bearing a neomenthyl group and a pentyl group attached at the 9-position of fluorene backbone at various ratios. The folded structure is formed and stabilized through inter-chain interactions in the solid state, leading to remarkably enhanced chiroptical properties (chirality amplification) in terms of circular dichroism (CD) and circularly polarized light (CPL) emission. This phenomenon is rationalized by experimental and theoretical CD and CPL spectral analyses.

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  • Researchers studied a 14mer peptide from the human copper transporter Ctr1 to understand how it binds metal ions, focusing on its ability to import copper into cells.
  • The peptide has specific motifs that are selective for different metal ions, and it can bind to these ions in varying oxidation states.
  • Experiments showed that at neutral pH, Cu(II) binds tightly to the peptide, but at lower pH levels, the binding changes, allowing for potential reduction to Cu(I) and indicating different coordination preferences under acidic conditions.
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Optically active linear polyurethane and a cyclic dimer were synthesized from 2,7-diisocyanatofluorene and 2,2'-dihydroxy-1,1'-binaphthyl. The circular dichroism (CD) spectral intensity of the polymer was amplified at a higher concentration through aggregate formation, while circularly polarized light (CPL) emission was not enhanced. The cyclic dimer's CPL emission was largely amplified ( 1.

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  • The study examined the photo racemization process of BINOL and its various ethers using circular dichroism, chiral HPLC, and energy barrier calculations.
  • BINOL underwent racemization the quickest, while its monomethyl and monobutyl ethers reacted about seven times slower.
  • The dimethyl ether showed such slow racemization rates that it couldn't be measured under the conditions tested.*
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  • Recent advancements in π-conjugated polymers are notable due to their light-sensitive torsional changes, impacting their unique light-emitting properties.
  • A new computational framework was created to better understand these changes by improving torsional conformational sampling and calculating energy differences from ground to excited states, using methods like Hamiltonian Replica Exchange Method and metadynamics.
  • The study focused on a specific polymer model, revealing that it can dramatically change its dihedral angle upon light exposure, with significant energy barriers that can affect its stability and emission properties,* highlighting a good match between simulation results and experimental data.
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Preferred-handed propeller conformation was induced by circularly polarized light irradiation to three amorphous molecules with trigonal symmetry, and the molecules with induced chirality efficiently exhibited blue circularly polarized luminescence. In both chirality induction and luminescence, chirality appeared to be amplified due to intermolecular interactions through π-stacking.

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Islet amyloid polypeptide (IAPP) is a hormone co-secreted with insulin and zinc from pancreatic β-cells. To overcome the low solubility of human IAPP, we characterized zinc complexes species formed with 1) a mutated form of rat-IAPP(1-37; R18 H) able to mimic the human IAPP, 2) the r-IAPP(1-37) and the IAPP(1-8) fragment. Stoichiometry, speciation and coordination features of zinc(II) complexes were unveiled by ESI-MS, potentiometry and NMR measurements combined with DFT and free-energy simulations.

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The circular dichroism spectra of a single chain of polyfluorene was predicted for a p-twisted helix conformation and local planarized polymer sections in the presence and in the absence of thermal vibrations. Under thermal vibrations at 300 K, the planarized section of polyfluorene affords a red-shifted positive dichroic band between 446 and 456 nm, preserving a degree of chirality. The S1 ← S0 excitation energy decreases from 3.

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The comprehensive characterization of Intramolecular Charge Transfer (ICT) stemming in push-pull molecules with a delocalized π-system of electrons is noteworthy for a bespoke design of organic materials, spanning widespread applications from photovoltaics to nanomedicine imaging devices. Photo-induced ICT is characterized by structural reorganizations, which allows the molecule to adapt to the new electronic density distribution. Herein, we discuss recent photophysical advances combined with recent progresses in the computational chemistry of photoactive molecular ensembles.

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Proteasome malfunction parallels abnormal amyloid accumulation in Alzheimer's Disease (AD). Here we scrutinize a small library of pyrazolones by assaying their ability to enhance proteasome activity and protect neuronal cells from amyloid toxicity. Tube tests evidenced that aminopyrine and nifenazone behave as 20S proteasome activators.

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The opossum is a peculiar model of immunity to prion diseases. Here we scrutinised the bis-decarepeat peptide sequence of the opossum prion (Op_bis-deca) protein by a multitechnique approach, with a combined experimental (potentiometry, UV-visible, circular dichroism, NMR and EPR spectroscopy, quartz crystal microbalance with dissipation monitoring and confocal microscopy) and simulation (DFT calculations) approach. Results showed that the macrochelate structures formed upon the binding to Cu(ii) by the analogous bis-octarepeat peptide sequence of human prion (Hu_bis-octa) are not found in the case of Op_bis-deca.

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Nerve growth factor (NGF) is a protein necessary for development and maintenance of the sympathetic and sensory nervous systems. We have previously shown that the NGF N-terminus peptide NGF(1-14) is sufficient to activate TrkA signaling pathways essential for neuronal survival and to induce an increase in brain-derived neurotrophic factor (BDNF) expression. Cu ions played a critical role in the modulation of the biological activity of NGF(1-14).

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  • The text discusses the properties of π-rich conjugated polymers and molecular rotors, particularly focusing on oligofluorenes used in optoelectronics.
  • It introduces a computational method based on classical simulations to estimate the free-energy gap between ground and excited states, utilizing free-energy perturbation theory.
  • The results demonstrate that the calculated excitation energies align well with experimental data, offering a reliable way to sample conformational landscapes and assess excited state free-energy landscapes.
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The binding of the human nerve growth factor (NGF) protein to tropomyosin receptor kinase A (TrkA) is associated with Alzhemeir's development. Owing to the large presence of zinc(II) ions in the synaptic compartments, the zinc ions might be bound to the complex in vivo. Here, we have identified a putative zinc binding site using a combination of computations and experiments.

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The copper-binding features of rat islet amyloid polypeptide (r-IAPP) are herein disclosed through the determination of the stability constants and spectroscopic properties of its copper complex species. To mimic the metal binding sites of the human IAPP (h-IAPP), a soluble, single-point mutated variant of r-IAPP, having a histidine residue in place of Arg18, was synthesized, that is, r-IAPP(1-37; R18H). The peptide IAPP(1-8) was also characterized to have deeper insight into the N-terminus copper(II)-binding features of r-IAPP as well as of its mutated form.

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We reconstructed the free-energy landscape for supramolecular nanoparticles of amphiphilic methacrylated-based co-polymers. Their self-assembly in aqueous solution and encapsulation of borondipyrromethene (BODIPY) derivatives were enforced through atomistic free-energy simulations. The BODIPY binding modes detected in each of the free-energy basins were validated through a comparison of theoretical absorption spectra, calculated at the TD-DFT level, to their experimental counterparts.

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The nerve growth factor (NGF) N-terminus peptide, NGF(1-14), and its acetylated form, Ac-NGF(1-14), were investigated to scrutinize the ability of this neurotrophin domain to mimic the whole protein. Theoretical calculations demonstrated that non-covalent forces assist the molecular recognition of TrkA receptor by both peptides. Combined parallel tempering/docking simulations discriminated the effect of the N-terminal acetylation on the recognition of NGF(1-14) by the domain 5 of TrkA (TrkA-D5).

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