Analysis of the Relaxometric Properties of Extremely Rapidly Exchanging Gd3+ Chelates: Lessons from a Comparison of Four Isomeric Chelates.

Relaxometric analyses and in particular the use of fast-field cycling techniques have become routine in the study of paramagnetic metal complexes. The field dependence of the solvent proton relaxation properties (nuclear magnetic relaxation dispersion, NMRD) can provide unparalleled insights into the chemistry of these complexes. However, analyzing NMRD data is a multiparametric problem, and some sets of variables are mutually compensatory. Specifically, when fitting NMRD profiles, the metal-proton distance and the rotational correlation time constant have a push-pull relationship in which a change to one causes a predictable compensation in the other. A relaxometric analysis of four isomeric chelates highlights the pitfalls that await when fitting the NMRD profiles of chelates for which dissociative water exchange is extremely rapid. In the absence of independently verified values for one of these parameters, NMRD profiles can be fitted to multiple parameter sets. This means that NMRD fitting can inadvertently be used to buttress a preconceived notion of how the complex should behave when a different parameter set may more accurately describe the actual behavior. These findings explain why the effect of very rapid dissociative exchange on the hydration state of Gd3+ has remained obscured until only recently.

Importance of outer-sphere and aggregation phenomena in the relaxation properties of phosphonated gadolinium complexes with potential applications as MRI contrast agents.

A series composed of a tetra-, a tris- and a bisphosphonated ligand based on a pyridine scaffold (L(4) , L(3) and L(2) , respectively) was studied within the frame of lanthanide (Ln) coordination. The stability constants of the complexes formed with lanthanide cations (Ln=La, Nd, Eu, Gd, Tb, Er and Lu) were determined by potentiometry in aqueous solutions (25.0 °C, 0.1 M NaClO4 ), showing that the tetraphosphonated complexes are among the most stable Ln(III) complexes reported in the literature. The complexation of L(4) was further studied by different titration experiments using mass spectrometry and various spectroscopic techniques including UV/Vis absorption, and steady state and time-resolved luminescence (Ln=Eu and Tb). Titration experiments confirmed the formation of highly stable [LnL(4) ] complexes. (31) P NMR experiments of the LuL(4) complex revealed an intramolecular interconversion process which was studied at different temperatures and was rationalized by DFT modelling. The relaxivity properties of the Gd(III) complexes were studied by recording their (1) H NMRD profiles at various temperatures, by temperature dependent (17) O NMR experiments (GdL(4) ) and by pH dependent relaxivity measurements at 0.47 T (GdL(3) and GdL(2) ). In addition to the high relaxivity values observed for all complexes, the results showed an important second-sphere contribution to relaxivity and pH dependent variations associated with the formation of aggregates for GdL(2) and GdL(3) . Finally, intravenous injection of GdL(4) to a mouse was followed by dynamic MRI imaging at 1.5 T, which showed that the complex can be immediately found in the blood stream and rapidly eliminated through the liver and in large part through the kidneys.

Aggregation in amphiphilic macrocycle-substituted Gd(3+) DOTA-type chelates is affected by the regiochemistry of substitution.

Gd(3+) chelates of macrocyclic bifunctional chelators (BFCs) can differentiate into two regioisomers: corner and side. These isomers afford different orientations of chelate relative to conjugate. These differences alter the self-assembly, tumbling, and effectiveness as magnetic resonance imaging contrast agents of the two biphenyl conjugate isomers.

A new ditopic Gd(III) complex functionalized with an adamantyl moiety as a versatile building block for the preparation of supramolecular assemblies.

A dimeric GdAAZTA-like complex (AAZTA is 6-amino-6-methylperhydro-1,4-diazepinetetraacetic acid) bearing an adamantyl group (Gd2L1) able to form strong supramolecular adducts with specific hosts such as ß-cyclodextrin (ß-CD), poly-ß-CD, and human serum albumin (HSA) is reported. The relaxometric properties of Gd2L1 were investigated in aqueous solution by measuring the (1)H relaxivity as a function of pH, temperature, and magnetic field strength. The relaxivity of Gd2L1 (per Gd atom) at 40 MHz and 298 K is 17.6 mM(-1) s(-1), a value that remains almost constant at higher fields owing to the great compactness and rigidity of the bimetallic chelate, resulting in an ideal value for the rotational correlation time for high-field MRI applications (1.5-3.0 T). The noncovalent interaction of Gd2L1 with ß-CD, poly-ß-CD, and HSA and the relaxometric properties of the resulting host-guest adducts were investigated using (1)H relaxometric methods. Relaxivity enhancements of 29 and 108 % were found for Gd2L1-ß-CD and Gd2L1-poly-ß-CD, respectively. Binding of Gd2L1 to HSA (KA = 1.2 × 10(4) M(-1)) results in a remarkable relaxivity of 41.4 mM(-1) s(-1) for the bound form (+248 %). The relaxivity is only limited by the local rotation of the complex within the binding site, which decreases on passing from Gd2L1-ß-CD to Gd2L1-HSA. Finally, the applicability of Gd2L1 as tumor-targeting agent through passive accumulation of the HSA-bound adduct was evaluated via acquisition of magnetic resonance images at 1 T of B16-tumor-bearing mice. These experiments indicate a considerable signal enhancement (+160 %) in tumor after 60 min from the injection and a very low hepatic accumulation.

Design of Injectable Bioartificial Hydrogels by Green Chemistry for Mini-Invasive Applications in the Biomedical or Aesthetic Medicine Fields.

Bioartificial hydrogels are hydrophilic systems extensively studied for regenerative medicine due to the synergic combination of features of synthetic and natural polymers. Injectability is another crucial property for hydrogel mini-invasive administration. This work aimed at engineering injectable bioartificial in situ cross-linkable hydrogels by implementing green and eco-friendly approaches. Specifically, the versatile poly(ether urethane) (PEU) chemistry was exploited for the development of an amphiphilic PEU, while hyaluronic acid was selected as natural component. Both polymers were functionalized to expose thiol and catechol groups through green water-based carbodiimide-mediated grafting reactions. Functionalization was optimized to maximize grafting yield while preserving group functionality. Then, polymer miscibility was studied at the macro-, micro-, and nano-scale, suggesting the formation of hydrogen bonds among polymeric chains. All hydrogels could be injected through G21 and G18 needles in a wide temperature range (4-25 °C) and underwent sol-to-gel transition at 37 °C. The addition of an oxidizing agent to polymer solutions did not improve the gelation kinetics, while it negatively affected hydrogel stability in an aqueous environment, suggesting the occurrence of oxidation-triggered polymer degradation. In the future, the bioartificial hydrogels developed herein could find application in the biomedical and aesthetic medicine fields as injectable formulations for therapeutic agent delivery.

Thiol-Ene Photo-Click Hydrogels with Tunable Mechanical Properties Resulting from the Exposure of Different -Ene Moieties through a Green Chemistry.

Temperature and light responsiveness are widely exploited stimuli to tune the physico-chemical properties of double network hydrogels. In this work, new amphiphilic poly(ether urethane)s bearing photo-sensitive moieties (i.e., thiol, acrylate and norbornene functionalities) were engineered by exploiting the versatility of poly(urethane) chemistry and carbodiimide-mediated green functionalization procedures. Polymers were synthesized according to optimized protocols maximizing photo-sensitive group grafting while preserving their functionality (approx. 1.0 × 1019, 2.6 × 1019 and 8.1 × 1017 thiol, acrylate and norbornene groups/gpolymer), and exploited to prepare thermo- and Vis-light-responsive thiol-ene photo-click hydrogels (18% w/v, 1:1 thiol:ene molar ratio). Green light-induced photo-curing allowed the achievement of a much more developed gel state with improved resistance to deformation (ca. 60% increase in critical deformation, γL). Triethanolamine addition as co-initiator to thiol-acrylate hydrogels improved the photo-click reaction (i.e., achievement of a better-developed gel state). Differently, L-tyrosine addition to thiol-norbornene solutions slightly hindered cross-linking, resulting in less developed gels with worse mechanical performances (~62% γL decrease). In their optimized composition, thiol-norbornene formulations resulted in prevalent elastic behavior at lower frequency compared to thiol-acrylate gels due to the formation of purely bio-orthogonal instead of heterogeneous gel networks. Our findings highlight that exploiting the same thiol-ene photo-click chemistry, a fine tuning of the gel properties is possible by reacting specific functional groups.

Adsorption Features of Various Inorganic Materials for the Drug Removal from Water and Synthetic Urine Medium: A Multi-Technique Time-Resolved In Situ Investigation.

Pharmaceutical active compounds, including hundreds of different substances, are counted among the emerging contaminants in waterbodies, whose presence raises a growing concern for the ecosystem. Drugs are metabolized and excreted mainly through urine as an unchanged active ingredient or in the form of metabolites. These emerging contaminants are not effectively removed with the technologies currently in use, making them a relevant environmental problem. This study proposes the treatment of urine and water at the source that can allow an easier removal of dissolved drugs and metabolites. The treatment of synthetic urine, with dissolved ibuprofen as a model compound, by adsorption, using various classes of inorganic materials, such as clays, hierarchical zeolites and ordered mesoporous silica (MCM-41), is presented. A multi-technique approach involving X-ray powder diffraction, solid-state NMR, UV-Vis and Raman spectroscopies was employed to investigate the adsorption process in inorganic adsorbents. Moreover, the uptake, the ensuing competition, the efficiency and selectivity as well as the packing of the model compound in ordered mesoporous silica during the incipient wetness impregnation process were all thoroughly monitored by a novel approach, involving combined complementary time-resolved in situ 1H and 13C MAS NMR spectroscopy as well as X-ray powder diffraction.

Injectable supramolecular hydrogels based on custom-made poly(ether urethane)s and α-cyclodextrins as efficient delivery vehicles of curcumin.

A strategy to enhance drug effectiveness while minimizing controversial effects consists in exploiting host-guest interactions. Moreover, these phenomena can induce the self-assembly of physical hydrogels as effective tools to treat various pathologies (e.g., chronic wounds or cancer). Here, two Poloxamers®/Pluronics® (P407/F127 and P188/F68) were utilized to synthesize various LEGO-like poly(ether urethane)s (PEUs) to develop a library of tunable and injectable supramolecular hydrogels for drug delivery. Three PEUs were synthesized by chain extending Poloxamer/Pluronic with 1,6-cyclohexanedimethanol or N-Boc serinol. Other two amino-functionalized and highly responsive polymers were obtained thorough Boc-group cleavage. For hydrogel design, the spontaneous self-assembly of the poly(ethylene oxide) domains of PEUs with α-cyclodextrins was exploited to form poly(pseudo)rotaxanes (PPRs). PPR-derived channel-like crystals were characterized by X-Ray powder diffraction, Infra-Red and Proton Nuclear Magnetic Resonance spectroscopies. Cytocompatible hydrogel formulations were designed at PEU concentrations between 1% and 5% w/v and α-cyclodextrin at 10% w/v. Supramolecular gels showed good mechanical performances (storage modulus up to 20 kPa) coupled with marked thixotropic and self-healing properties (mechanical recovery over 80% within 30 s after cyclic rupture) as assessed through rheology. Hydrogels exhibited stability and high responsiveness in watery environment up to 5 days: the release of less stable components as suitable drug carriers was coupled with high swelling (doubling the content of fluids with respect to their dry mass) and shape retention. Curcumin was encapsulated into the hydrogels at high concentration (80 µg ml-1) through its complexation with α-cyclodextrins and delivery tests showed controllable and progressive release profiles up to four days.

Dramatic increase of selectivity for heavy lanthanide(III) cations by tuning the flexibility of polydentate chelators.

Two novel octadentate ligands have been synthesized by attaching two terminal iminodiacetic groups to either 1,4-diazepane (BCAED) or piperazine (BCAEP) as central scaffold. The introduction of the seven- or six-membered ring into the ligand backbone is expected to modify their overall flexibility and then to affect the stability of the corresponding lanthanide(III) complexes. In this work, thermodynamic stability data are determined for the formation of the complexes of BCAED and BCAEP with La(3+), Nd(3+), Eu(3+), Gd(3+), Ho(3+), and Lu(3+). The ligand BCAED shows a strong binding affinity for Lu(3+) (logK = 20.99), moderate for Gd(3+) (logK = 17.15) and rather weak for La(3+) (logK = 12.77). Thus, the variation of logK across the Ln series assumes the remarkable value of 8.22, the largest so far reported. This points to a predominant role of a suitable size match between the metal ion and the ligand cavity, determined by its structure and flexibility. The ligand BCAEP forms less stable complexes with lanthanide(III) cations although it retains a good selectivity (DeltalogK(La-Lu) = 5.66). The Gd(III) complexes have been investigated in aqueous solution by measuring their relaxivity as a function of pH, at 20 MHz and 25 degrees C. The results can be interpreted very well in terms of the species distribution curves calculated from the thermodynamic data and indicate that in these complexes Gd(3+) is octacoordinated, without any bound water molecule. This coordination geometry is maintained in the solid state as shown by the X-ray crystal structure of [Na(H(2)O)(2)][Gd(BCAED)] where the metal ion is at the center of a bicapped-trigonal prism. Finally, the (13)C NMR spectra (9.4 T, 25 degrees C) of the diamagnetic La(3+), Y(3+), and Lu(3+) complexes show that a pronounced stereochemical rigidity is associated with the thermodynamically more stable complexes.

Relationship between polyphenolic content, antioxidant properties and oxygen consumption rate of different tannins in a model wine solution.

The polyphenolic content and the antioxidant capacity of seven tannins with different botanical origin were measured with spectrophotometric methods (Folin-Ciocalteu, Total Polyphenols Index, DPPH, FRAP), HPLC (phloroglucinolysis), voltammetric analysis (Linear Sweep Voltammetry, LSV). The oxygen consumption rate (OCR) was measured in an oxygen saturated model wine solution, containing transition metals and metabisulphite, with a noninvasive luminescence-based technology. The results showed a high variability in polyphenolic concentration related to the botanical origin of tannins. The OCR determined over 21 days was described by quadratic equations, with coefficients varying with tannin botanical origin, dose and SO2 concentration. The tannins ranked differently for antioxidant capacity, depending on the kind of test. The oxygen consumption parameters were positively correlated only with the LSV data measured with anodic current between 100 and 1200 mV (LSV1200mV) and with the FRAP index.

Polyphenolic Composition and In Vitro Antioxidant Activity of Red Grape Seeds as Byproducts of Short and Medium-Long Fermentative Macerations.

The polyphenolic composition and antioxidant activity of grape seeds, as byproducts of red winemaking, depend on various factors, such as grape cultivar, vintage effect, grape maturity and winemaking methods. In the present work, the influence of the maceration length on the polyphenolic and antioxidant characteristics of the seeds of four Italian red grape cultivars ('Barbera', 'Grignolino', 'Nebbiolo', and 'Uvalino'), sampled from the fermentation tanks after short (two days) and medium-long (7-21 days) macerations, was studied with spectrophotometric methods, high-performance liquid chromatography (HPLC), and three different antioxidant assays (2,2'-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid (ABTS), ferric reducing antioxidant power (FRAP) and 2,2 diphenyl-1-picrylhydrazyl (DPPH)). The total polyphenolic content (gallic acid equivalent (GAE)) of the seeds sampled after short macerations ranged between 24.5 and 60.1 mg/g dry weight (DW), and it dropped to 20.0-37.5 mg/g DW after medium-long macerations. The polyphenolic profile of the shortly macerated seeds was related to the varietal characteristics, while, after longer macerations, the influence of the maceration length prevailed on the cultivar effect. The multiple in vitro antioxidant activity tests (ABTS, FRAP and DPPH), although based on different mechanisms capable of highlighting behavioral differences between the different polyphenolic compounds, were highly correlated with each other and with the polyphenolic parameters; the qualitative differences between the matrices in the polyphenolic profile were probably less important than the quantitative differences in the polyphenolic content. The relations with the polyphenolic content were linear, except for the Efficient Concentration (EC20) parameter, whose relation was better described by a hyperbolic equation.

Supramolecular hydrogels based on custom-made poly(ether urethane)s and cyclodextrins as potential drug delivery vehicles: design and characterization.

The design of supramolecular (SM) hydrogels based on host-guest complexes represents an effective strategy to develop drug delivery systems. In this work, we designed SM hydrogels based on α-cyclodextrin and high-molar mass amphiphilic poly(ether urethane)s (PEUs, ) based on Poloxamer® 407 and differing in their chain extender. The successful formation of poly(pseudo)rotaxanes and their supramolecular interactions were chemically demonstrated. Then, self-healing (80-100% mechanical recovery) supramolecular hydrogels were developed by mixing PEU and α-cyclodextrin solutions at different concentrations. Stability in physiological-like environment and mechanical properties improved with increasing α-cyclodextrin content (9-10% w/v), meanwhile gelation time decreased. A synergistic effect of poly(pseudo)rotaxanes crystals and PEU micellar structures on gel properties was observed: the first were predominant at low PEU concentrations (1-5% w/v), while the latter prevailed at high PEU concentrations (7-9% w/v). Increasing PEU concentration led to gels with increased dissolution rate, not-fully developed networks and slight cytotoxicity, meanwhile residence time in aqueous media improved (>7 d). At low PEU concentrations (1-5% w/v), cytocompatible gels (100% cell viability) were obtained, which maintained their shape in aqueous medium up to 5 d and completely dissolved within 7 d. PEU chemical composition affected PEU/α-cyclodextrin interactions, with longer gelation time and lower mechanical properties in gels based on PEU with pendant functionalities. Gels progressively released a model molecule (fluorescein isothiocyanate-dextran) within 3-4 days with no initial burst release. We thus demonstrated the suitability of custom-made PEUs as constituent of SM hydrogels with α-cyclodextrin and the high potential of the resulting systems for drug delivery applications.

Embedding Ordered Mesoporous Carbons into Thermosensitive Hydrogels: A Cutting-Edge Strategy to Vehiculate a Cargo and Control Its Release Profile.

The high drug loading capacity, cytocompatibility and easy functionalization of ordered mesoporous carbons (OMCs) make them attractive nanocarriers to treat several pathologies. OMCs' efficiency could be further increased by embedding them into a hydrogel phase for an in loco prolonged drug release. In this work, OMCs were embedded into injectable thermosensitive hydrogels. In detail, rod-like (diameter ca. 250 nm, length ca. 700 nm) and spherical (diameter approximately 120 nm) OMCs were synthesized by nanocasting selected templates and loaded with ibuprofen through a melt infiltration method to achieve complete filling of their pores (100% loading yield). In parallel, an amphiphilic Poloxamer® 407-based poly(ether urethane) was synthesized (Mn¯ 72 kDa) and solubilized at 15 and 20% w/v concentration in saline solution to design thermosensitive hydrogels. OMC incorporation into the hydrogels (10 mg/mL concentration) did not negatively affect their gelation potential. Hybrid systems successfully released ibuprofen at a slower rate compared to control gels (gels embedding ibuprofen as such), but with no significant differences between rod-like and spherical OMC-loaded gels. OMCs can thus work as effective drug reservoirs that progressively release their payload over time and also upon encapsulation in a hydrogel phase, thus opening the way to their application to treat many different pathological states (e.g., as topical medications).

Hybrid Injectable Sol-Gel Systems Based on Thermo-Sensitive Polyurethane Hydrogels Carrying pH-Sensitive Mesoporous Silica Nanoparticles for the Controlled and Triggered Release of Therapeutic Agents.

Injectable therapeutic formulations locally releasing their cargo with tunable kinetics in response to external biochemical/physical cues are gaining interest in the scientific community, with the aim to overcome the cons of traditional administration routes. In this work, we proposed an alternative solution to this challenging goal by combining thermo-sensitive hydrogels based on custom-made amphiphilic poly(ether urethane)s (PEUs) and mesoporous silica nanoparticles coated with a self-immolative polymer sensitive to acid pH (MSN-CS-SIP). By exploiting PEU chemical versatility, Boc-protected amino groups were introduced as PEU building block (PEU-Boc), which were then subjected to a deprotection reaction to expose pendant primary amines along the polymer backbone (PEU-NH2, 3E18 -NH2/gPEU-NH2) with the aim to accelerate system response to external acid pH environment. Then, thermo-sensitive hydrogels were designed (15% w/v) showing fast gelation in physiological conditions (approximately 5 min), while no significant changes in gelation temperature and kinetics were induced by the Boc-deprotection. Conversely, free amines in PEU-NH2 effectively enhanced and accelerated acid pH transfer (pH 5) through hydrogel thickness (PEU-Boc and PEU-NH2 gels covered approximately 42 and 52% of the pH delta between their initial pH and the pH of the surrounding buffer within 30 min incubation, respectively). MSN-CS-SIP carrying a fluorescent cargo as model drug (MSN-CS-SIP-Ru) were then encapsulated within the hydrogels with no significant effects on their thermo-sensitivity. Injectability and in situ gelation at 37°C were demonstrated ex vivo through sub-cutaneous injection in rodents. Moreover, MSN-CS-SIP-Ru-loaded gels turned out to be detectable through the skin by IVIS imaging. Cargo acid pH-triggered delivery from PEU-Boc and PEU-NH2 gels was finally demonstrated through drug release tests in neutral and acid pH environments (in acid pH environment approximately 2-fold higher cargo release). Additionally, acid-triggered payload release from PEU-NH2 gels was significantly higher compared to PEU-Boc systems at 3 and 4 days incubation. The herein designed hybrid injectable formulations could thus represent a significant step forward in the development of multi-stimuli sensitive drug carriers. Indeed, being able to adapt their behavior in response to biochemical cues from the surrounding physio-pathological environment, these formulations can effectively trigger the release of their payload according to therapeutic needs.

Wine evolution during bottle aging, studied by 1H NMR spectroscopy and multivariate statistical analysis.

The study of wine evolution during bottle aging is an important aspect of wine quality. Ten different red wines (Vitis vinifera) from Piedmont region were analysed 3 months after bottling and after a further 48 month conservation in a climate controlled wine cellar kept at a constant/controlled temperature of 12 °C. Two white wines (Vitis vinifera) were included in this study for comparison purposes. White wines were analysed 3 months after bottling and after further 24 months of bottle aging in the same climate controlled wine cellar. Metabolite changes during this period were evaluated using 1H NMR spectroscopy combined with statistical analysis. Metabolite variations due to wine aging were minimal compared to those that resulted from a different wine type and wine geographical origin. Therefore, it was necessary to remove this source of variability to discriminate between fresh and refined samples. The storage at low and controlled temperature for 2 or 4 years permitted a slow but progressive evolution of all wines under investigation. 1H NMR spectroscopy, implemented with statistical data analysis, allowed identifying and differentiating wine samples from the two aging stages. In most wines, a decrease in organic acids (lactic acid, succinic acid and tartaric acid) and an increase in esters (ethyl acetate and ethyl lactate) was observed. Catechin and epicatechin decreased during aging in all wines while gallic acid increased in almost all red wines.

Plasma Treatment of Polymer Powder as an Effective Tool to Functionalize Polymers: Case Study Application on an Amphiphilic Polyurethane.

Plasma treatment is a widely applied, easy, fast, and highly reproducible surface modification technique. In this work powder plasma treatment was exploited to expose carboxylic groups along the backbone of a water soluble polymer. Specifically, a custom-made amphiphilic poly(ether urethane) containing Poloxamer® 407 blocks (Mw = 54,000 Da) was first synthesized and its powders were plasma treated in the presence of Acrylic Acid vapor. To maximize -COOH group exposure while preventing polymer degradation, different Ar gas flow rates (i.e., 10, 30, and 50 sccm) were investigated. Upon gas flow increase, significant polymer degradation was observed, with a 35% molecular weight reduction at 50 sccm Ar flow rate. On the other hand, the highest number of exposed carboxylic groups (5.3 × 1018 ± 5.5 × 1017 units/gpolymer) was obtained by setting gas flow at 10 sccm. Hence, a gas flow of 10 sccm turned out to be the best set-up to maximize -COOH exposure while preventing degradation phenomena. Additionally, upon plasma treatment, no detrimental effects were observed in the thermoresponsiveness of polymer aqueous solutions, which was ensured by Poloxamer® 407 blocks. Therefore, the newly developed technology here applied on an amphiphilic poly(ether urethane) could pave the way to the tailored design of a plethora of different multifunctional hydrogels.

Newly-designed collagen/polyurethane bioartificial blend as coating on bioactive glass-ceramics for bone tissue engineering applications.

In the present work, a new combination of synthetic and natural biomaterials is proposed for bone tissue engineering (BTE) applications. In order to mimic the inorganic and organic phases of bone extracellular matrix (ECM), a bioactive glass-ceramic deriving from a SiO2-P2O5-CaO-MgO-Na2O-K2O parent glass, acting as a substrate in form of a slice, was surface-functionalised with a type I collagen-based coating. In particular, the collagen was blended with a water soluble polyurethane (PUR), synthesised from poly(ethylene glycol), 1,6-hexamethylene diisocyanate and N-BOC-serinol. The PUR was designed to expose amino groups on the polymeric chain, which can be exploited for the blend stabilisation through crosslinking. The newly synthesised PUR demonstrated to be non-cytotoxic, as assessed by a biological test with MG-63 osteoblast-like cells. The collagen/PUR blend showed good biocompatibility as well. The polymeric coating on the glass-ceramic samples was produced by surface-silanisation, followed by further chemical grafting of the blend, using genipin as a crosslinker. The glass-ceramic surface was characterised at each functionalisation step, demonstrating that the procedure allowed obtaining a covalent link between the blend and the substrate. Finally, biological tests performed using human periosteal derived precursor cells demonstrated that the proposed polymer-coated material was a good substrate for bone cell adhesion and growth, and a good candidate to mimic the composite nature of the bone ECM.

Radical scavenging abilities of fish MT-A and mussel MT-10 metallothionein isoforms: An ESR study.

Metallothioneins (MTs) are cysteine-rich proteins involved in homeostasis of essential metals, detoxification of toxic metals and scavenging of free radicals. Scavenging of the stable 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical was measured by means of ESR spectroscopy for two recombinant MTs from aquatic species: MT-10 from the sea mussel Mytilus galloprovincialis, and MT-A from the fish Oncorhyncus mykiss. Both the zinc- and the cadmium-loaded forms (Zn(7)-MTs and Cd(7)-MTs) were analysed, using the commercial MT-II (Zn(7)-MT-II and Cd(7)-MT-II, respectively) from rabbit liver as a reference. A decrease in the scavenging ability was observed for all the three MTs passing from the Zn- to the Cd-loaded forms, because of the higher stability of the Cd-mercapto complex. The Zn(7)-MTs from aquatic species were more effective in scavenging DPPH signal than the rabbit Zn(7)-MT-II (2.8 and 4-folds, respectively). Similar results were obtained also for the Cd(7)-MTs, thus confirming the stronger antioxidant power of MTs from aquatic organisms compared with the rabbit MT-II. Moreover, mussel MT-10 was more active in DPPH scavenging than fish MT-A. When the complete release of metals from MTs was obtained by lowering the pH to 3 or, alternatively, by adding the chelating agent diethylenetriaminepentaacetic acid (DTPA), an increase in the scavenging ability of MTs was observed.

Haemolymph from Mytilus galloprovincialis: Response to copper and temperature challenges studied by (1)H-NMR metabonomics.

Numerous studies on molluscs have been carried out to clarify the physiological roles of haemolymph serum proteins and haemocytes. However, little is known about the presence and functional role of the serum metabolites. In this study, Nuclear Magnetic Resonance (NMR) was used to assess whether changes of the metabolic profile of Mytilus galloprovincialis haemolymph may reflect alterations of the physiological status of the organisms due to environmental stressors, namely copper and temperature. Mussel haemolymph was taken from the posterior adductor muscle after a 4-day exposure to ambient (16 °C) or high temperature (24 °C) and in the absence or presence (5 µg/L, 20 µg/L, or 40 µg/L) of sublethal copper (Cu(2+)). The total glutathione (GSH) concentration in the haemolymph of both control and treated mussels was minimal, indicating the absence of significant contaminations by muscle intracellular metabolites due to the sampling procedure. In the (1)H-NMR spectrum of haemolymph, 27 metabolites were identified unambiguously. The separate and combined effects of exposure to copper and temperature on the haemolymph metabolic profile were assessed by Principal Component Analysis (PCA) and Ranking-PCA multivariate analysis. Changes of the metabolomic profile due to copper exposure at 16 °C became detectable at a dose of 20 µg/L copper. Alanine, lysine, serine, glutamine, glycogen, glucose and protein aliphatics played a major role in the classification of the metabolic changes according to the level of copper exposition. High temperature (24 °C) and high copper levels caused a coherent increase of a common set of metabolites (mostly glucose, serine, and lysine), indicating that the metabolic impairment due to high temperature is enforced by the presence of copper. Overall, the results demonstrate that, as for human blood plasma, the analysis of haemolymph metabolites represents a promising tool for the diagnosis of pollutant-induced stress syndrome in marine mussels.

Cytotoxicity of cis-platinum(II) conjugate models. The effect of chelating arms and leaving groups on cytotoxicity: a quantitative structure-activity relationship approach.

Thirteen newly synthesized or resynthesized diamine-platinum(II) complexes were characterized, and their cytotoxic activities (IC50) were tested on parental and resistant ovarian cancer cell lines. They represent models of conjugates between biologically active vectors and cytotoxic Pt(II) moieties within the "drug targeting and delivery strategy". Three drugs, routinely employed in the clinical treatment of cancer, namely, cisplatin, carboplatin, and oxaliplatin, were also included in the study as controls. The quantitative structure-activity relationship approach provides simple regression models able to predict log(1/IC50) of diamine-platinum(II) complexes on both parental and resistant ovarian cancer cell lines. The 16 complexes were characterized using 197 molecular descriptors, after which the best regression models relating a subset of these descriptors to the log(1/IC50) in the two cancer cell lines were calculated. Models with four variables proved to be endowed with very good predictive ability Q2(LMO-50%) > or = 85.6%, making it possible to discard 50% of the molecules from the test set following for cross-validation procedure. A four-variable regression model also proved effective in predicting the resistance index RI, Q2(LMO-50%) = 84.4%.