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Conjugated polyelectrolytes (CPEs) have recently emerged as label-free materials for biosensing due to their intrinsic ability to transduce an amplified optical signal in response to interactions with different analytes. Herein, the conformational change of an anionic oligothiophene is exploited to generate a unique fluorescent response upon interaction with myristoylcholine (MyrCh). The variations observed in spectroscopic signals are explained in terms of a synergistic combination of hydrophobic and electrostatic forces involving the oligothiophene chains and MyrCh molecules, inducing the disassembling of oligothiophene chains. The enzyme acetylcholinesterase (AChE) is able to reverse this effect by catalyzing the hydrolysis of MyrCh; hence, its enzymatic activity can be monitored through the variation of fluorescence emission of the system. The oligothiophene sensing probe retains its conformational sensitivity with regard to the AChE-mediated cleavage of MyrCh upon immobilization onto a quartz substrate, which is accomplished by a "grafting onto" approach based on click chemistry. These results are encouraging for the further development of such a label-free system towards the fabrication of sensing devices that would incorporate CPEs and would be potentially useful for the specific detection of a wide range of bioanalytes. This journal is

Correction for ‘Wound healing properties of hyaluronan derivatives bearing ferulate residues’ by Giuseppe Valacchi et al., J. Mater. Chem. B, 2015, DOI: 10.1039/c5tb00661a.

In order to obtain new advanced functional materials capable of recognizing drug molecules, the polybenzofulvene backbone of molecular brush poly-6-MOEG-9-TM-BF3k has been functionalized with a “synthetic dynamic receptor” composed of two 1-adamantylurea moieties linked together by means of a dipropyleneamino bridge as in Meijer's bis(adamantylurea) pincer (BAUP). This functional material, bearing synthetic receptors potentially capable of recognizing/loading and then delivering drug molecules, was used to prepare colloidal drug delivery systems (by means of soft interaction with BAUP) for delivering the model anti-cancer drug doxorubicin (DOXO). The resulting nanostructured drug delivery systems containing the physically loaded drug were characterized in terms of drug loading and release, dimensions and zeta potential, and in vitro cell activity and uptake on two different cell lines (i.e. the human bronchial epithelial 16HBE and the human colon cancer HCT116). On normal cells, free DOXO was found to be more cytotoxic than DOXO-loaded nanogels at the higher tested concentration and, only on cancer cells, DOXO-loaded nanogels show similar or slightly higher cytotoxicity values than free DOXO, suggesting potential advantages in the treatment of cancer. These results were supported by fluorescence microscopy studies, which suggested that DOXO-loaded nanogels provide an extracellular reservoir of the drug, which is gradually released and internalized within the cells.

The development of simple, low-cost and selective methods for quantitative detection of mercury ions in aqueous media is still a challenge. Herein, we employ a cysteine based perylene diimide (PDI-Cys) as sensing probe for Hg2+ ions in water. The probe selectively detects the mercury ions in 100% aqueous solution by a fluorescence turn-on response. The binding stoichiometry reveals a 1:2 complexation of PDI-Cys/Hg2+, in which two Hg2+ ions are bound to one PDI-Cys molecule. The detection limit is as low as 20 ppb, close to the sensitivity requirement for drinking water, indicating the potentiality of PDI-based probes for mercury analysis in both environmental and biological field.

We report on the straightforward preparation and photophysical characterization of four symmetrically substituted water soluble perylene diimides, obtained by functionalizing the imide positions with l -threonine, l -aspartic acid, l -cysteine and l -methionine. The presence of carboxylic groups on the two sides of the aromatic structure conveys a pH-dependent water solubility to all the molecules. The combined effect of the hydrophobic perylene core with the specific aminoacidic functionalities leads to different aggregation behaviors in both aqueous and organic media affecting the optical absorption and emission of the aromatic chromophore. By a comparative study of the optical properties we shed light on the main characteristics of these perylene derivatives in organic and aqueous diluted solution. These aminoacid perylene diimide molecules have the potential to be exploited in new sensing applications based on assembly/disassembly-driven fluorescence switching off-on in aqueous media.

Two small series of quinoline derivatives were designed starting from previously published quinoline derivatives 7a and b in order to obtain information about their interaction with the 5-HT(4)R binding site. Initially, the structure of 7a and b was modified by replacing their basic moiety with that of partial agonist 4 (ML10302) or with that of reference ligand 6 (RS-67-333). Then, the aromatic moieties of 4-quinolinecarboxylates 7a, d–f, and h–k or 4-quinolinecarboxamides 7b, c, and g were modified into those of 2-quinolinecarboxamides 9a–e. Very interestingly, this structure–affinity relationship study led to the discovery of 7h–j as novel 5-HT(4)R ligands showing K(i) values in the subnanomolar range. The structures of all these compounds contain the N-butyl-4-piperidinylmethyl substituent, which appear to behave as an optimized basic moiety in the interaction of these 4-quinolinecarboxylates with the 5-HT(4)R binding site. However, this basic moiety was ineffective in providing 5-HT(4)R affinity in the corresponding 4-quinolinecarboxamide 7g, but it did in 2-quinolinecarboxamide ligands 9c–e. Thus, a subtle interrelationship of several structural parameters appeared to play a major role in the interaction of the ligands with the 5-HT(4)R binding site. They include the kind of basic moiety, the position of the carbonyl linking group with respect to the aromatic moiety and its orientation, which could be affected by the presence of the intramolecular H-bond as in compounds 9c–e.

Perylene diimide derivatives containing pendant cysteine residues are subjected to a strong self-assembly onto [1 1 1] Au films due to the presence of thiol functionality. The preparation of two different Au surfaces easies the understanding of both surface packing and morphology of the aggregated ordered films, by means of the combination of X-ray photoelectron spectroscopy, atomic force microscopy, and grazing incident wide X-ray scattering - synchrotron radiation - techniques. A proper correlation of the resulting data, together with conformational calculations - using a detailed molecular modelling - allow supplying a coherent scenario. In particular, isolated ordered pillars upstanding to the substrate plane are detected on native gold surface, while a π-stacked aggregation “unregistered” normally to the film plane is observed when perylene derivatives are grafted onto thermally annealed gold surface. Such a surface organization is expected to be favourable to the charge mobility, therefore its use in organic field effect transistor is envisioned.

In order to develop a technology platform based on two natural compounds from biorenewable resources, a short series of hyaluronan (HA) copolymers grafted with propargylated ferulic acid (HA-FA-Pg) were designed and synthesized to show different grafting degree values and their optical properties were characterized in comparison with reference compounds containing the same ferulate fluorophore. Interestingly, these studies revealed that the ferulate fluorophore was quite sensitive to the restriction of intramolecular motion and its introduction into the rigid HA backbone, as in HA-FA-Pg graft copolymers, led to higher photoluminescence quantum yield values than those obtained with the isolated fluorophore. Thus, the propargyl groups of HA-FA-Pg derivatives were exploited in the coupling with oleic acid through a biocompatible nona(ethylene glycol) spacer as an example of the possible applications of this technology platform. The resulting HA-FA-NEG-OA materials showed self-assembling capabilities in aqueous environment. Furthermore, HA-FA-NEG-OA derivatives have been shown to interact with phospholipid bilayers both in liposomes and living cells, retaining their fluorogenic properties and showing a high degree of cytocompatibility and for this reason they were proposed as potential biocompatible self-assembled aggregates forming new materials for biomedical applications.

Spontaneous polymerization is an intriguing phenomenon in which pure monomers begin their polymerization without initiators or catalysts. Previously, 3-phenylbenzofulvene monomers were found to polymerize spontaneously after solvent removal. Here, eight new 3-substituted benzofulvene monomers 1a&ndash, h were synthesized in order to investigate the effects of differently substituted aromatic rings in position 3 of the benzofulvene scaffold on spontaneous polymerization. The newly synthesized monomers maintained the tendency toward spontaneous polymerization. However, monomer 1a, bearing an ortho-methoxy substituted phenyl, polymerized hardly, thus producing low polymerization yields, inhomogeneous structure, and low molecular weight of the obtained polymeric material. This result suggested the importance of the presence of hydrogen atoms in the 2&prime, position to achieve productive interactions among the monomers in the recognition step preluding the spontaneous polymerization and among the monomeric units in the polybenzofulvene backbones. Moreover, this study paves the way to modify the pendant rings in position 3 of the indene scaffold to synthesize new polybenzofulvene derivatives variously decorated.

A tri-component polymer brush (TCPB), composed of a polybenzofulvene copolymer bearing low molecular weight hyaluronic acid (HA) on the surface of its cylindrical brush-like backbone and oligo-PEG fractions, was employed in the preparation of 350Â nm nanostructured drug delivery systems capable of delivering the anticancer drug doxorubicin. The obtained drug delivery systems were characterized on the basis of drug loading and release, dimensions and zeta potential, morphology and in vitro cell activity, and uptake on three different human cell lines, namely the bronchial epithelial 16HBE, the breast adenocarcinoma MCF-7, and the colon cancer HCT116 cells. Finally, the ability of doxorubicin-loaded TCPB nanoparticles (DOXO-TCPB) to be internalized into cancer cells by CD44 receptor mediated uptake was assessed by means of uptake studies in HCT cells. These data were supported by anti-CD44-FITC staining assay. The proposed TCPB nanostructured drug delivery systems have many potential applications in nanomedicine, including cancer targeted drug delivery.

This paper reports on the assessment of a simple and economical self-assembly methodology to obtain reproducible infstrates onto the optical fiber tip for surface-enhanced Raman spectroscopy (SERS) applications. The method relies on the use of the nanosphere lithography of the optical fiber end facet. A careful analysis has been carried out to investigate the capability of the proposed procedure to realize repeatable pattern on the optical fiber tip. Finally, we demonstrate the effective application of the patterned OFTs as SERS nanoprobes. © 2017 SPIE.

We report on the fabrication and repeatability assessment of patterned substrates onto the optical fibre tip for surface-enhanced Raman spectroscopy (SERS) applications. In the route of "Lab on Fiber" Technology, indeed, we developed a simple an inexpensive self-assembly technique to create ordered and regular nanostructures on the optical fibre tip. The fabrication technique is borrowed from nanosphere lithography and it is adapted to operate on the cleaved end of standard optical fibre tips. This technique has been used to create different nanostructures with completely different morphological features on the fibre tip. The repeatability of the fabricated structures is here analyzed by using Focused Ion Beam Microscopy (FIBM) and Atomic Force Microscopy (AFM). The morphological analysis allowed to assess the nanospheres pattern regularity by systematically measuring the nanostructures features sizes and the number of defect for unit area. The analyzed samples have been also characterized spectrally to quantify the effective impact of the defect formation on the samples spectral response. Finally, the capability of the samples to act as SERS probes has been verified by detecting low concentrations (1 μM) of Crystal Violet diluted in an aqueous solution.

Two new benzofulvene derivatives bearing a fluorene chromophore in different positions of the phenylindene scaffold were synthesized and induced to polymerize spontaneously. The photophysical investigation evidenced the role of the substitution topology of the monomeric units in the optical properties of the corresponding polymers. In particular, the polymer emission efficiency was found to improve both in solution and in the solid state when the fluorene residue enhances monomer conjugation and rigidity. The ability of this newly synthesized class of polymers to self-organize in supramolecular structures is evidenced through a study on blends with a benzothiadiazole based dye at different concentrations. Aggregation quenching processes of the dye are sharply reduced and complete resonant energy transfer from the polymer to the dye is reached even at 1% dye concentration. The peculiar ability of this new class of pi-stacked polymers to self-assemble in such a supramolecular organization suggests their use as platforms for the design of more complex nanostructured films with enhanced optical and optoelectronic properties.

A series of imidazo[1,5-a]quinoline derivatives was designed and synthesized as central benzodiazepine receptor (CBR) ligands. Most of the compounds showed high CBR affinity with Ki values within the submicromolar and subnanomolar ranges with interesting modulations in their structure-affinity relationships. In particular, fluoroderivative 7w (Ki = 0.44 nM) resulted in the most potent ligand among the imidazo[1,5-a]quinoline derivatives described so far. Overall, these observations confirmed the assumption concerning the presence of a large though apparently saturable lipophilic pocket in the CBR binding site region interacting with positions 4 and 5 of the imidazo[1,5-a]quinoline nucleus. The in vivo biological characterization revealed that compounds 7a,c,d,l,m,q,r,w show anxiolytic and antiamnestic activities without the unpleasant myorelaxant side effects of the classical 1,4-BDZ. Furthermore, the effect of 7l,q,r, and 8i in lowering lactate dehydrogenase (LDH) release induced by ischemia-like conditions in rat brain slices suggested neuroprotective properties for these imidazo[1,5-a]quinoline derivatives.

Hyaluronic acid (HA) forms pericellular coats in many cell types that are involved in the early stages of cell adhesion by interacting with the CD44 receptor. Based on the largely recognized overexpression of the CD44 receptor in tumor tissues, a polybenzofulvene molecular brush has been enveloped into hyaluronan shells to obtain a tri-component polymer brush (TCPB) composed of intrinsically fluorescent backbones bearing nona(ethylene glycol) arms terminated with low molecular weight HA macromolecules. The nanoaggregates obtained in TCPB water dispersions were characterized on the basis of dimensions, zeta potential, and in vitro cell toxicity. This biomimetic multifunctional material bearing HA on the surface of its cylindrical brush architecture showed promising prerequisites for the preparation of nanostructured drug delivery systems.

Polybenzofulvenes are π-stacked polymers, which can be synthesized by spontaneous polymerization of the corresponding monomers without the use of catalysts or initiators. Therefore, they can be obtained completely free from byproducts, impurities, or harmful substances. The absence of any relevant toxic effects and cell viability impairments allows PEGylated polybenzofulvene brushes to be potentially functional in a wide range of biological, biomedical, and biotechnological applications. Moreover, the properties of these polymers, in terms of interaction with pharmacological active agents and the ability to self-assemble into nanoaggregates or a quite compact physical gel useful as drug delivery systems (DDSs), can be controlled by varying side chain moieties. Owing to the important role played by self-assembling DDS in the fields of the material and life sciences, the interaction and the delivery ability of polybenzofulvene polymers with model drug or protein molecules was definitively demonstrated. The present paper reviews the applications of polybenzofulvene derivatives in the drug delivery of a range of different drug molecules ranging from small molecules to peptides and proteins.

The modulation of assembly/disassembly of perylene diimide derivatives (PDIs) represents an intriguing challenge for fluorescence sensing purposes. Herein, an aminoacid-functionalized PDI (PDI-Thr) is selected as a conformationally-sensitive probe which transduces the modification of its aggregation state into an optical response. Photoluminescence measurements reveal that the emission of PDI-Thr in aqueous solution can be finely modulated by a cationic surfactant, myristoylcholine chloride (MyrCh). Fluorescence sensing studies illustrate that the PDI-Thr/MyrCh ensembles exhibit an emission intensity variation in response to the enzymatic activity of acetylcholinesterase, which is able to reverse the surfactochromic effect by catalyzing the hydrolysis of MyrCh. Detailed NMR investigations elucidate the supramolecular mechanism behind the sensing behavior. This study sheds light on the synergistic combination of electrostatic and hydrophobic interactions occurring between PDI-Thr and MyrCh, leading to the fluorescent ensemble which is responsible for the sensing performance. The discussed results outline that the development of fluorophore/surfactant ensembles based on water soluble PDIs have great potential for the label-free sensing of a wide range of analytes and enzymes.

In this work, we report a straightforward and cost-effective fabrication route for the development of nano-patterned optical fiber tips. The technique is based on self-assembling polystyrene microspheres at the air/water interface and on their successive transferring on the fiber tip of single mode optical fiber. By applying to the fiber further treatments like particle size reduction, metal coating and sphere removal, different periodic structures have been conveniently realized. The morphological analysis reveals indeed the successful creation on the optical fiber tip of regular metallic-dielectric spheres' arrays as well as metallic patterns with dimensional features down to a submicron scale. Finally, as proof of concept, we demonstrated the capability of the realized patterns to work as efficient Surface Enhanced Raman Spectroscopy (SERS) fiber probes. © 2016 SPIE.

Four new benzofulvene derivatives bearing bithiophene chromophores at two different key positions of the phenylindene scaffold were prepared in order to evaluate the role of different chromophores in the optoelectronic features of polybenzofulvene derivatives. The results of the photophysical studies showed that the optical properties of the newly-synthesized bithiophene-functionalized polymers were affected by both the polymer enchainment and the substitution topology of the monomeric units. On the other hand, the hole-mobility appeared to be affected to a lesser extent, but the best performances were obtained in poly-6-HBT-BF3k showing the strongest bithiophene side chain packing. This work demonstrates that the optoelectronic properties of polybenzofulvene derivatives can be optimized by a targeted chemical design such as side chain engineering.

In this work, we report a fabrication route for self-assembling periodic patterns on optical fiber tips. The technique is based on self-assembling polystyrene microspheres at the air/water interface and on successive transferring of the monolayer colloidal crystal on the fiber tip. By applying to the fiber further treatments like particle size reduction, metal coating and sphere removal, different periodic structures are conveniently realized. The results obtained indicate that self-assembly technique affords opportunity to create on the optical fiber tip dielectric and metallic-dielectric spheres' arrays with a feature size down to a submicron scale or metallic patterns with a few hundred nanometers at low fabrication costs. © (2015) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.

A new class of π-stacked polymers possessing interesting charge transport properties is represented by polydibenzofulvene derivatives. We study the electroluminescence properties of three π-stacked polybenzofulvene derivatives and compare them to those of the standard π-stacked poly(N-vinylcarbazole). Solution processable devices using one of these polymers as host with benzothiadiazole based dyes display performances overcoming those of the standard poly(N-vinylcarbazole) host. From a photophysical study, the superior performances of the polybenzofulvene containing a fluorene unit at the position 6 of the indene nucleus are explained to arise from its ability to self-assemble with the dyes in supramolecular organizations that reduce their microaggregation.

This paper reports a simple and economical method for the fabrication of nanopatterned optical fiber nanotips. The proposed patterning approach relies on the use of the nanosphere lithography of the optical fiber end facet. Polystyrene (PS) nanospheres are initially self-assembled in a hexagonal array on the surface of water. The created pattern is then transferred onto an optical fiber tip (OFT). The PS monolayer colloidal crystal on the OFT is the basic building block that is used to obtain different periodic structures by applying further treatment to the fiber, such as metal coating, nanosphere size reduction and sphere removal. Ordered dielectric and metallo-dielectric sphere arrays, metallic nanoisland arrays and hole-patterned metallic films with feature sizes down to the submicron scale are achievable using this approach. Furthermore, the sizes and shapes of these periodic structures can be tailored by altering the fabrication conditions. The results indicate that the proposed self-assembly approach is a valuable route for the development of highly repeatable metallo-dielectric periodic patterns on OFTs with a high degree of order and low fabrication cost. The method can be easily extended to simultaneously produce multiple fibers, opening a new route to the development of fiber-optic nanoprobes. Finally, we demonstrate the effective application of the patterned OFTs as surface-enhanced Raman spectroscopy nanoprobes.

A synthetic procedure has been developed to conjugate ferulic acid (FA) to an important natural polysaccharide derivative such as hyaluronic acid (HA). The activation of FA with 1,1'-carbonyldiimidazole (CDI) has been investigated. Two reactive intermediates, namely monoimidazolide 2 [i.e. (E)-3-(4-hydroxy-3-methoxyphenyl)-1-(1H-imidazol-1-yl)prop-2-en-1-one] and bisimidazolide 3 [i.e. (E)-4-(3-(1H-imidazol-1-yl)-3-oxoprop-1-enyl)-2-methoxyphenyl 1H-imidazole-1-carboxylate] were characterized from the point of view of their structure and reactivity. The ready isolation of bisimidazolide 3 and its reactivity support its potential usefulness in the feruloylation of molecular or macromolecular materials bearing hydroxyl moieties. Bisimidazolide derivative 3 has been found to be an effective reagent in the feruloylation of HA to give HAFA graft copolymers showing different grafting degrees (GD), which could be modulated by varying the reaction conditions. A series of HAFA derivatives showing different GD values has been prepared and submitted to an extensive macromolecular and rheological characterization in order to ascertain that the grafting of HA with FA does not degrade the polysaccharide backbone and to evaluate the role of GD in affecting solubility and rheological properties. The results suggested that relatively low GD values were sufficient to confer physical cross-linking capabilities resulting in the features of a strong gel of HAFA dispersions.

Serendipity has often played a pivotal role in research and, in harmony with this function, it has had a fundamental responsibility in the discovery of the thermoreversible spontaneous polymerization of benzofulvene derivatives. After a decade from the discovery of poly-BF1, the present chapter narrates the history of polybenzofulvene derivatives from the discovery to the latest developments. Now that more than 50 polymers belonging to this family have been synthesized and the relevant studies have been published in the most important journals dealing with polymer science, the spontaneous polymerization of benzofulvene monomers and the special features of the corresponding polymers appear to become a well-established topic. The chapter provides an in-depth analysis of the literature on the subject, from the preparation methods to the characterization of polybenzofulvene derivatives, the study of their properties, and the evaluation of the possible applications.

Two new benzofulvene derivatives bearing two or three methoxy substituents on the benzene ring were synthesized and induced to polymerize spontaneously in order to investigate the photophysical and electronic properties of the corresponding polymers. The photophysical features of the newly synthesized polymers suggested a high degree of pi-stacking both in the solid state and in diluted solutions, and the large Stokes shift was interpreted in terms of an efficient energy transfer within the excimer. Absorption and emission features in the solid state were found to be similar to those in diluted solutions and the stable PL quantum yield was considered a promising feature with regard to the potential applications of the polymers in light emitting devices. Finally, the remarkable hole mobility shown by poly-4,5,6-MO-BF3k along with the enhancing effect of the methoxy substituents in the charge mobility opens up new routes to the development of materials potentially useful in optoelectronics.

A new biorelevant polymer brush showing a polybenzofulvene backbone was synthesized by a ‘‘grafting through’’ approach based on click chemistry and spontaneous polymerization reactions. The easy polymerization of the relatively complex monomer (6-MOEG-9-TM-BF3k) suggests the existence of a particularly efficient recognition process capable of pre-organizing the monomer molecules for the spontaneous polymerization. 13C-NMR spectroscopy as well as UV-vis and fluorescence spectroscopy suggested for poly-6-MOEG-9-TM-BF3k the features of a vinyl (1,2) p-stacked polymer. The new polybenzofulvene derivative was found to interact with water at room temperature to give clear water solutions, but TEM analysis demonstrated the presence of macromolecular aggregates showing dimensions larger than those suggested by SEC-MALS analysis for the isolated macromolecules. DLS studies confirmed the presence of objects showing average dimensions in the range of 200–300 nm and suggested thermoresponsive colloidal properties for poly-6-MOEG-9-TM-BF3k macromolecules. Finally, owing to its favourable absorption/emission properties and water solubility, the interaction of poly-6-MOEG-9-TM-BF3k with live cells was studied by fluorescence microscopy experiments, which revealed that the polymer brush was unable to enter live cells and alter cell morphology.