Elvira De Giglio

Characterization and evaluation of chitosan nanoparticles for dopamine brain delivery

The aim of this study was to characterize nanoparticles (NPs) composed of chitosan (CS) and evaluate their potential for brain delivery of the neurotransmitter Dopamine (DA). For this purpose, CS based NPs were incubated with DA at two different concentrations giving rise to nanocarriers denoted as DA/CSNPs (1) and DA/CSNPs (5), respectively. X-ray Photoelectron Spectroscopy (XPS) analysis confirmed that DA was adsorbed onto the external surface of such NPs. The cytotoxic effect of the CSNPs and DA/CSNPs was assessed using the MTT test and it was found that the nanovectors are less cytotoxic than the neurotransmitter DA after 3 h of incubation time. Transport studies across MDCKII-MDR1 cell line showed that DA/CSNPs (5) give rise to a significant transport enhancing effect compared with the control and greater than the corresponding DA/CSNPs (1). Measurement of reactive oxygen species (ROS) suggested a low DA/CSNPs neurotoxicity after 3 h. In vivo brain microdialysis experiments in rat showed that intraperitoneal acute administration of DA/CSNPs (5) (6-12 mg/kg) induced a dose-dependent increase in striatal DA output. Thus, these CS nanoparticles represent an interesting technological platform for DA brain delivery and, hence, may be useful for Parkinsons disease treatment.

Spectroscopic investigation on polymer films obtained by oxidation of o-phenylenediamine on platinum electrodes at different pHs

An investigation on the structure of poly(o-phenylenediamine) (PPD) films, obtained by electropolymerization of oPD (1,2-diaminobenzene) on platinum at different pH values, was performed by X-ray Photoelectron Spectroscopy (XPS). XPS could be used as a “bulk” technique for PPD films analysis, due to their extremely low thickness. The presence of different functionalities, like primary/secondary aminic, iminic and, as minor species, oxygenated groups (carbonyl, oximes) was suggested by curve fitting of carbon (C1s) and nitrogen (N1s) XP spectra. The use of chemical derivatization reactions (CD–XPS) confirmed the presence of primary aminic and hydroxy groups, showing that NH2 groups are present in the PPD structure even at low pH values, though their amount increases on increasing the pH of polymerization. Optical spectroscopy in the visible region was also performed on the electrolytic solutions at the end of polymerization, suggesting a higher conjugation of the oPD oligomers at low pH, which indirectly confirms XPS findings on the presence of NH2 groups in the polymer.

Characterization and cytocompatibility of an antibiotic/chitosan/ cyclodextrins nanocoating on titanium implants

A novel ciprofloxacin loaded chitosan nanoparticle-based coating onto titanium substrates has been developed and characterized to obtain an orthopaedic implant surface able to in situ release the antibiotic for the prevention of post-operative infections. Ciprofloxacin loaded chitosan nanoparticles were obtained using the combination of sulfobutyl ether-beta-cyclodextrin and gamma-cyclodextrin. The resulting nanoparticulate system was characterized by TEM, HPLC and XPS. Particle size was in the range 426-552 nm and zeta potential values were around +30 mV. This antibacterial coating was able to in vitro inhibit two nosocomial Staphylococcus aureus strains growth, with a reduction of about 20 times compared to controls. No impairment in MG63 osteoblast-like cells viability, adhesion and gene expression were detected at 48 h, 7 and 14 days of culture. Overall, the investigated coating represents a promising candidate for the development of a new antibiotic carrier for titanium implants.

Development and characterization of rhVEGF-loaded poly(HEMA-MOEP) coatings electrosynthesized on titanium to enhance bone mineralization and angiogenesis.

Osteointegration of titanium implants could be significantly improved by coatings capable of promoting both mineralization and angiogenesis. In the present study, a copolymeric hydrogel coating, poly-2-hydroxyethyl methacrylate-2-methacryloyloxyethyl phosphate (P(HEMA-MOEP)), devised to enhance calcification in body fluids and to entrap and release growth factors, was electrosynthesized for the first time on titanium substrates and compared to poly-2-hydroxyethyl methacrylate (PHEMA), used as a blank reference. Polymers exhibiting negatively charged groups, such as P(HEMA-MOEP), help to enhance implant calcification. The electrosynthesized coatings were characterized by X-ray photoelectron spectroscopy and atomic force microscopy. MG-63 human osteoblast-like cell behaviour on the coated specimens was investigated by scanning electron microscopy, MTT viability test and osteocalcin mRNA detection. The ability of negatively charged phosphate groups to promote hydroxyapatite-like calcium phosphate deposition on the implants was explored by immersing them in simulated body fluid. Similar biological responses were observed in both coated specimens, while calcium-phosphorus globules were detected only on P(HEMA-MOEP) surfaces pretreated with alkaline solution. Testing of the ability of P(HEMA-MOEP) hydrogels to entrap and release human recombinant vascular endothelial growth factor, to tackle the problem of insufficient oxygen and nutrient delivery, suggested that P(HEMA-MOEP)-coated titanium prostheses could represent a multifunctional material suitable for bone restoration applications.

Intranasal delivery of dopamine to the striatum using glycol chitosan/sulfobutylether-β-cyclodextrin based nanoparticles.

The aim of this study was to evaluate chitosan (CS)-, glycol chitosan (GCS)- and corresponding thiomer-based nanoparticles (NPs) for delivering dopamine (DA) to the brain by nasal route. Thus, the polyanions tripolyphosphate and sulfobutylether-β-cyclodextrin (SBE-β-CD), respectively, were used as polycation crosslinking agents and SBE-β-CD also in order to enhance the DA stability. The most interesting formulation, containing GCS and SBE-β-CD, was denoted as DA GCS/DA-CD NPs. NMR spectroscopy demonstrated an inclusion complex formation between SBE-β-CD and DA. X-ray photoelectron spectroscopy analysis revealed the presence of DA on the external surface of NPs. DA GCS/DA-CD NPs showed cytotoxic effect toward Olfactory Ensheathing Cells only at higher dosage. Acute administration of DA GCS/DA-CD NPs into the right nostril of rats did not modify the levels of the neurotransmitter in both right and left striatum. Conversely, repeated intranasal administration of DA GCS/DA-CD NPs into the right nostril significantly increased DA in the ipsilateral striatum. Fluorescent microscopy of olfactory bulb after acute administration of DA fluorescent-labeled GCS/DA-CD NPs into the right nostril showed the presence of NPs only in the right olfactory bulb and no morphological tissue damage occurred. Thus, these GCS based NPs could be potentially used as carriers for nose-to-brain DA delivery for the Parkinsons disease treatment.

Permanent iridium modifier deposited on tungsten and zirconium-treated platforms in electrothermal atomic absorption spectrometry: vaporization of bismuth, silver and tellurium

The stabilizing role of permanent Ir modifier deposited on W-treated (WTP) and Zr-treated (ZrTP) platforms of transversely heated graphite atomizer (THGA) was studied in detail by electrothermal at. absorption spectrometry (ETAAS) and different surface techniques in model expts. for Ag, Bi and Te. The comparison of the stabilizing efficiency of permanent Ir modifier on WTP and ZrTP and each of the single components, reveals the better effect of Ir on WTP and Ir itself. The extent of analyte losses during pre-atomization and the strength of analyte assocn. with the modifier were estd. by the plotting of differential vaporization curves. The existence of double peaks of Ag, Bi and Te in WTP and Ir on WTP was confirmed and possible reasons for their formation are discussed. The absorbance profiles presented as differential curves reveal an existence of at least two different types of precursors detg. processes of atom generation. The obsd. differences in the behavior of Ir permanent modifier on WTP and ZrTP, resp., were explained by the different extent of Ir-W and Ir-Zr interaction and surface distribution. XRF, ESCA and SEM studies reveal nonuniform distribution of the modifier on the graphite substrate and the presence of oxide contg. species on the surface. [on SciFinder (R)]

Analytical characterization and antimicrobial properties of novel copper nanoparticle–loaded electrosynthesized hydrogel coatings

In this study, a novel antimicrobial coating was developed to avoid infections and to provide sterile conditions for stainless steel devices. Poly(ethylene glycol diacrylate) hydrogel thin films were modified with copper-based nanoparticles, following two different entrapment procedures. These coatings were firmly attached on metal substrates by means of a simple and fast electrochemical polymerization technique. The surface composition of the Cu nanoparticles–modified hydrogel coatings and their bactericidal effect against Staphylococcus aureus and Escherichia coli was studied, and the efficacy of such systems in preventing bacterial infections demonstrated.

Insight Into Halloysite Nanotubes-Loaded Gellan Gum Hydrogels For Soft Tissue Engineering Applications

A tri-component hydrogel, based on gellan gum (GG), glycerol (Gly) and halloysite nanotubes (HNT), is proposed in this work for soft tissue engineering applications. The FDA-approved GG polysaccharide has been recently exploited as biomaterial because its biomimetic features. Gly is added as molecular spacer to improve hydrogel viscosity and mechanical properties. HNT incorporation within the hydrogel offers the versatility to improve the GG-Gly biocompatibility with potential incorporation of target biomolecules. In this work, hydrogels with different composition ratios are physically crosslinked for tuning physico-mechanical properties. An accurate physico-chemical characterization is reported. HNT addition leads to a water uptake decrease of 30-35% and tuneable mechanical properties with a compressive Youngs modulus ranging between 20 and 75kPa. Finally, in vitro study with human fibroblasts on GG-Gly hydrogels loaded with 25% HNT offered the higher metabolic activities and cell survival up to 7days of incubation.

Rh3+ and Rh3+–diamine complexes intercalated in γ-titanium hydrogen phosphate. Synthesis, characterisation and catalytic activity towards aniline oxidative carbonylation processes

Abstract New materials containing Rh(III) ions or Rh(III)–diamine complexes [(L=2,2′-bipyridyl (bipy); 1,10-phenanthroline (phen); 2,9-dimethyl-1,10-phenanthroline (dmp)] intercalated in γ-titanium phosphate (γ-TiP) are described. The compounds have formula γ-TiPHxRhy·tH2O (x=2–3y; 0

Surface segregation assessment in poly(ε-caprolactone)-poly(ethylene glycol) multiblock copolymer films

The ability to predict the in vivo performance of multiblock-copolymer-based biomaterials is crucial for their applicability in the biomedical field. In this work, XPS analysis of PCL-PEG copolymers was carried out, as well as morphological and wettability evaluations by SEM and CA measurements, respectively. XPS analysis on films equilibrated in PBS demonstrated a further enrichment in the PEG component on the surface. Copolymer films obtained by casting using different solvents showed a dependence in segregation according to the solvent employed. Cell adhesion tests demonstrated the importance of copolymer segregation and rearrangement in a wet environment, with a dependence of these phenomena on the copolymer molecular weight.