Gabriele Giancane

State of art in porphyrin Langmuir–Blodgett films as chemical sensors

Porphyrins are tetrapyrrolic macrocycles with a fascinating and multifarious variegation of properties of essential significance in up-to-date and leading technologies. From a different point of view, the Langmuir-Blodgett technique allows the immobilisation of films with an accurate regulation of molecular organisation and thickness. As a logical upshot, this manuscript concerns a substantial object of consideration in contemporary research, the utilisation of Langmuir-Blodgett multilayers of porphyrins in sensing elements for the detection of analytes in different matrices. Investigations on the morphological, optical, structural and surface characteristics of these films are remarkably related to the significant properties of sensors with the ultimate goal of rationalising the innermost intercourses between the sensing behaviour and the peculiarities and molecular organisation brought about by the deposition method. The integration of the typical electrical and optical characteristics of porphyrins with the potentialities of the Langmuir-Blodgett multilayer has originated not only encouraging projects but has afforded also certainties on the accomplishment of operative chemical sensors.

Supramolecular amplification of amyloid self-assembly by iodination

Amyloid supramolecular assemblies have found widespread exploitation as ordered nanomaterials in a range of applications from materials science to biotechnology. New strategies are, however, required for understanding and promoting mature fibril formation from simple monomer motifs through easy and scalable processes. Noncovalent interactions are key to forming and holding the amyloid structure together. On the other hand, the halogen bond has never been used purposefully to achieve control over amyloid self-assembly. Here we show that single atom replacement of hydrogen with iodine, a halogen-bond donor, in the human calcitonin-derived amyloidogenic fragment DFNKF results in a super-gelator peptide, which forms a strong and shape-persistent hydrogel at 30-fold lower concentration than the wild-type pentapeptide. This is remarkable for such a modest perturbation in structure. Iodination of aromatic amino acids may thus develop as a general strategy for the design of new hydrogels from unprotected peptides and without using organic solvents.

Functionalized Copper(II)−Phthalocyanine in Solution and As Thin Film: Photochemical and Morphological Characterization toward Applications

This article reports on an extensive investigation on a functionalized phthalocyanine, namely, copper(II) tetrakis-(isopropoxy-carbonyl)-phthalocyanine (TIPCuPc). The self-association of the molecules is extensively described in solution in different solvents (DMSO, DMF, CHCl(3), pyridine) by means of UV-vis steady state spectroscopy at the air/water interface by Brewster angle microscopy (BAM) and in thin films by using atomic force microscopy (AFM). We investigated the morphology of TIPCuPc as thin film by evaluating different factors: temperature, solvent, concentration, transferring procedure (spin-coating and Langmuir-Schafer technique), and nature of the substrate (mica and quartz). The behavior of the molecules under UV light irradiation and their thermal stability were studied as well. Such a detailed study can allow a suitable processing of this phthalocyanine derivative for future applications. Here the photoelectrochemical activity of the phthalocyanine was investigated when suitably combined as sensitizer with rodlike TiO(2) nanocrystals (NCs) in hybrid junctions integrated in a photoelectrochemical cell.

A smart method for the fast and low-cost removal of biogenic amines from beverages by means of iron oxide nanoparticles

Paramagnetic iron oxide nanoparticles have been synthetized and covered by a silica shell for a dual function: SiO2 capping improves the stability of the nanoparticles and at the same time promotes the bonding between the paramagnetic nanoparticles@SiO2 (MNPs@SiO2) and biogenic amines. The constituents of the paramagnetic nanoparticles have been identified to be magnetite and maghemite by Infrared and Raman spectroscopy; these optical investigations also allow confirmation of the key role of the capping layer in the interaction with the amines. The magnetic adducts with the biogenic amines can be removed simply and rapidly through the application of weak magnetic fields. The observation of the quickness and ease of biogenic amine elimination has prompted us to check the application of this new approach to real commercial wine samples containing these toxic fermentation products: their complete removal has been observed by absorption spectra, thus confirming the potential of this novel approach in agroindustrial areas and agribusiness.

Biocompatible Collagen Paramagnetic Scaffold for Controlled Drug Release.

A porous collagen-based hydrogel scaffold was prepared in the presence of iron oxide nanoparticles (NPs) and was characterized by means of infrared spectroscopy and scanning electron microscopy. The hybrid scaffold was then loaded with fluorescein sodium salt as a model compound. The release of the hydrosoluble species was triggered and accurately controlled by the application of an external magnetic field, as monitored by fluorescence spectroscopy. The biocompatibility of the proposed matrix was also tested by the MTT assay performed on 3T3 cells. Cell viability was only slightly reduced when the cells were incubated in the presence of the collagen-NP hydrogel, compared to controls. The economicity of the chemical protocol used to obtain the paramagnetic scaffolds as well as their biocompatibility and the safety of the external trigger needed to induce the drug release suggest the proposed collagen paramagnetic matrices for a number of applications including tissue engeneering and drug delivery.

Photoresponsive multilayer films by assembling cationic amphiphilic cyclodextrins and anionic porphyrins at the air/water interface

Densely packed hybrid monolayers of amphiphilic cyclodextrins incorporating hydrophilic porphyrins are formed at the air/water interface through electrostatic interaction and can be transferred onto quartz substrates by Langmuir–Schafer deposition. The resulting multilayers exhibit a good response to light excitation as proven by fluorescence emission, triplet–triplet absorption and singlet oxygen photogeneration.

Nitric oxide photoreleasing multilayer films

In this contribution we report the preparation and characterization of Langmuir–Schafer (LS) multilayer films of a mesogen-bearing cationic amphiphile able to release nitric oxide (NO) under the exclusive control of light stimuli. The morphology and spectroscopic features of the floating films at the water–air interface are inspected by Brewster angle microscopy and UV-Vis reflection spectroscopy, respectively. Multilayer films are obtained by horizontal lifting deposition onto hydrophobized quartz substrates and characterized by UV-Vis absorption spectroscopy. The capability of these films to deliver NO is investigated by the direct monitoring of this radical species through an ultrasensitive NO electrode. The results obtained unequivocally demonstrate that the multilayers are stable in the dark but, in contrast, supply NO at nanomolar level upon illumination with visible light.

Dual‐Function Multilayers for the Photodelivery of Nitric Oxide and Singlet Oxygen

In this contribution we report the design, preparation and characterization of bichromophoric Langmuir-Schäfer multilayer films which enable the simultaneous generation of nitric oxide (NO) and singlet oxygen (1)O(2) ((1)Delta(g)). They are achieved by exploiting effective interfacial electrostatic interactions between the floating film of a cationic amphiphilic nitric oxide (NO) photodonor and an anionic porphyrin dissolved in the water subphase. The morphology and the spectroscopic features of the floating films at the water-air interface are inspected by Brewster angle microscopy and UV/Vis reflection spectroscopy, respectively. Multilayer films containing both the chromogenic centres are obtained by horizontal lifting deposition onto hydrophobized quartz substrates and are characterized by steady-state UV/Vis absorption, fluorescence and laser flash photolysis. The anionic porphyrin units are entangled into the films network mainly in their monomeric forms and no significant intra and inter-chromophoric interaction occur in the excited state, preserving the photochemical independency of the two photoactive units in the multilayers. The capability of the bichromophoric films to delivery NO and singlet oxygen, (1)O(2) ((1)Delta(g)), under light excitation is unambiguously demonstrated by the direct and in real time monitoring of these transient species using an ultrasensitive electrode and a time-resolved infrared luminescence apparatus, respectively.

The supramolecular design of low-dimensional carbon nano-hybrids encoding a polyoxometalate-bis-pyrene tweezer

A novel bis-pyrene tweezer anchored on a rigid polyoxometalate scaffold fosters a unique interplay of hydrophobic and electrostatic supramolecular interactions, to shape carbon nanostructures (CNSs)-based extended architectures.

Langmuir-Schaefer films for aligned carbon nanotubes functionalized with a conjugate polymer and photoelectrochemical response enhancement.

Single-walled carbon nanotubes (SWCNTs) were suspended in 1,2-dichloroethane by noncovalent functionalization with a low-band-gap conjugated polymer 1 alternating dialkoxyphenylene-bisthiophene units with benzo[c][2,1,3]thiadiazole monomeric units. The suspended 1/SWCNT blend was transferred onto different solid substrates by the Langmuir-Schaefer deposition method, resulting in films with a high percentage of aligned nanotubes. Photoelectrochemical characterization of 1/SWCNT thin films on indium-tin oxide showed the benefits of SWCNT alignment for photoconversion efficiency.