Tunable gold nanorod/NAO conjugates for selective drug delivery in mitochondria-targeted cancer therapy.

Nonyl acridine orange (NAO) is a lipophilic and positively charged molecule widely used as a mitochondrial fluorescent probe. NAO is cytotoxic at micromolar concentration and might be potentially used as a mitochondria-targeted drug for cancer therapy. However, the use of NAO under conditions would be compromised by the unspecific interactions with off-target cells and negatively charged proteins present in the bloodstream.

Controlled pDNA Release in Gemini Cationic Lipoplexes by Femtosecond Laser Irradiation of Gold Nanostars.

The design of nanovectors able to overcome biological barriers is one of the main challenges in biomedicine. Gemini cationic lipids are considered potential candidates for gene therapy due to their high biocompatibility and capacity to condense nucleic acids safely in the form of lipoplexes. However, this approach presents difficulties regarding genetic unpacking and, therefore, control over this process becomes crucial to ensure successful transfection.

Protein Expression Knockdown in Cancer Cells Induced by a Gemini Cationic Lipid Nanovector with Histidine-Based Polar Heads.

A histidine-based gemini cationic lipid, which had already demonstrated its efficiency as a plasmid DNA (pDNA) nanocarrier, has been used in this work to transfect a small interfering RNA (siRNA) into cancer cells. In combination with the helper lipid monoolein glycerol (MOG), the cationic lipid was used as an antiGFP-siRNA nanovector in a multidisciplinary study. Initially, a biophysical characterization by zeta potential (ζ) and agarose gel electrophoresis experiments was performed to determine the lipid effective charge and confirm siRNA compaction.

Supramolecular Control over the Interparticle Distance in Gold Nanoparticle Arrays by Cyclodextrin Polyrotaxanes.

Amphiphilic nonionic ligands, synthesized with a fixed hydrophobic moiety formed by a thiolated alkyl chain and an aromatic ring, and with a hydrophilic tail composed of a variable number of oxyethylene units, were used to functionalize spherical gold nanoparticles (AuNPs) in water. Steady-state and time-resolved fluorescence measurements of the AuNPs in the presence of α-cyclodextrin (α-CD) revealed the formation of supramolecular complexes between the ligand and macrocycle at the surface of the nanocrystals. The addition of α-CD induced the formation of inclusion complexes with a high apparent binding constant that decreased with the increasing oxyethylene chain length.

σ-Hole···π and lone pair···π interactions in benzylic halides.

Intermolecular and intramolecular halogen···π interactions in benzylic halides (Ph-CR2-X; X = F, Cl, Br and I) derived from 7-phenylnorbornane were investigated. The imposed geometry of the 7-arylnorbornane moiety prevents the participation of intramolecular attractive interactions between the σ-hole region of the halogen atom and the π electrons of the aromatic ring. Crystallographic data show intermolecular halogen bonds in iodide 1 and bromide 2 in the solid state.

Polyrotaxane-mediated self-assembly of gold nanospheres into fully reversible supercrystals.

The use of a thiol-functionalized nonionic surfactant to stabilize spherical gold nanoparticles in water induces the spontaneous formation of polyrotaxanes at the nanoparticle surface in the presence of the macrocycle α-cyclodextrin. Whereas using an excess of surfactant an amorphous gold nanocomposite is obtained, under controlled drying conditions the self-assembly between the surface supramolecules provides large and homogenous supercrystals with hexagonal close packing of nanoparticles. Once formed, the self-assembled supercrystals can be fully redispersed in water.

Rational design of a nonbasic molecular receptor for selective NH4+/K+ complexation in the gas phase.

A new molecular receptor (1) for ammonium recognition has been designed and constructed by using only carbon atoms. This molecular receptor can co-exist in two different isoenergetic conformations but, upon complexation, the conformers are no longer isoenergetic, and a basket-shaped conformation becomes clearly more stable. The pre-organised tetrahedral structure of this basket-shaped molecule favours the complexation of ammonium ions by N-H⋅⋅⋅π interactions with the four phenyl groups of the host.

Electron delocalization in homoconjugated 7,7-diarylnorbornane systems: a computational and experimental study.

A joint computational-experimental study has been carried out to analyze the homoconjugative interactions in 7,7-diarylnorbornane (DPN) derivatives. The experimentally observed new bands in their UV/Vis have been accurately assigned by means of TD-DFT calculations. Both experimental data and computations show that aromatic homoconjugation in acyclic systems is an effective mechanism for electron delocalization that resembles the situation described for polyphenylenes and polyenes.

Efficient photoinduced energy transfer mediated by aromatic homoconjugated bridges.

A new donor-bridge-acceptor (D-B-A) dyad consisting of ruthenium(II) and iridium(III) species separated by an homoconjugated bridge derived from 7,7-diphenylnorbornane [Ir-Nor-Ru](3+) has been synthesised. The photophysical and electrochemical properties of the heterodinuclear complex have been compared with those of the analogous homodinuclear complexes [Ru-Nor-Ru](4+) and [Ir-Nor- Ir](2+) . Transient absorption spectra on the nanosecond and sub-picosecond timescales show, for the first time, that an homoconjugated bridge can mediate efficiently in the photoinduced energy transfer from the iridium(III) to the ruthenium(II) centres according to a Dexter-type mechanism.

Efficient electron delocalization mediated by aromatic homoconjugation in 7,7-diphenylnorbornane derivatives.

Efficient electron delocalization by aromatic homoconjugated 7,7-diphenylnorbornane (DPN) in alternated homoconjugated-conjugated block copolymers and reference compounds is revealed by photophysical and electrochemical measurements. The synthesis of the polymers was achieved by Suzuki polycondensation reaction. Effective electron delocalization by DPN is demonstrated by the significant red shifts observed in the absorption and emission spectra and the variation of the energy band gap of the polymers and monomeric model compounds in comparison to a series of oligophenylenes used as references (p-quaterphenyl, p-terphenyl, and biphenyl).

Synthesis of homoconjugated oligomers derived from 7,7-diphenylnorbornane.

A methodology for the synthesis of monodisperse homoconjugated oligomers (dimer, trimer, and tetramer) derived from cofacial 7,7-diphenylnorbornane (DPN) is described. Extended aromatic homoconjugation is observed in these oligomers as revealed by the electronic spectra. The effective homoconjugation length (EHL) is in the range of 4-5 DPN subunits.

Evidence for different types of water participation in the solvolysis of 1-adamantyl, tert-butyl, and methyl chlorides from density functional theory computations.

[structure: see text] The activation energy in the gas phase (deltaE(double dagger)) and the free energy of activation (deltaG(double dagger)) in water solution for the hydrolysis of the monohydrates of methyl chloride (MeCl), tert-butyl chloride (t-BuCl), and 1-adamantyl chloride (AdCl) have been computed with the B3LYP/631-G(d) method and the polarizable continuum (PCM) solvation model. There is a fair agreement between the deltaG(double dagger) values computed by us and the experimental data. The mechanistic implications of our computations are in severe contradiction with conventional representations.

Complexation behavior of a highly preorganized 7,7-diphenylnorbornane-derived macrocycle: towards the design of molecular clocks.

The syntheses of two new cyclophane hosts, 4 and 6, are described. The main difference between them is the higher degree of preorganization of 4 as a consequence of the inclusion of the 7,7-diphenylnorbornane (DPN) subunit. The inner cavity of 4 adopts a belt-shaped structure, while 6 has a twisted geometry.

Comprehensive study of the methyl effect on the solvolysis rates of bridgehead derivatives.

The effect of a bridgehead methyl group on the hydride ion affinity in the gas phase of bicyclo[1.1.1]pent-1-yl (1+), 1-norbornyl (3+), cubyl (5+), 1-adamantyl (7+), bicyclo[2.

An Experimental and Computational Study about the Effect of a Spirocyclopropane Group on the Solvolysis Rates of Bridgehead Triflates.

7',7'-Dimethylspiro[cyclopropane-1,2'-norbornan]-1'-yl triflate (9) was obtained and its solvolysis rates in buffered 60% aqueous ethanol were determined at different temperatures. The solvolytic behavior of 9 and other bridgehead derivatives (13-17, see Table 1) was studied by force-field, semiempirical and ab initio [B3LYP/6-31g(d)] methods. Cation 9(+) is a slightly pyramidal cyclopropylcarbinyl cation in a nearly perpendicular conformation, showing an sp(2)-like hybridization.