A Novel Method for the Preparation of Retinoic Acid-Loaded Nanoparticles

The goal of present work was to investigate the use of bioerodible polymeric nanoparticles as carriers of retinoic acid (RA), which is known to induce differentiation of several cell lines into neurons. A novel method, named “Colloidal-Coating”, has been developed for the preparation of nanoparticles based on a copolymer of maleic anhydride and butyl vinyl ether (VAM41) loaded with RA. Nanoparticles with an average diameter size of 70 nm and good morphology were prepared. The activity of the encapsulated RA was evaluated on SK-N-SH human neuroblastoma cells, which are known to undergo inhibition of proliferation and neuronal differentiation upon treatment with RA. The activity of RA was not affected by the encapsulation and purification processes

Palaeo-environmental reconstruction of the Mercure Basin (Basilicata region) during MIS 13, through a multi-proxy analysis of lacustrine sediments

The main purpose of this work is to make a first evaluation of the potential of the carbonate lacustrine sediment of the Mercure Basin (Basilicata region), to preserve palaeoclimatic information during the Middle Pleistocene. For this purpose a multi-proxy analysis of the lacustrine sediments from a selected section of the basin was undertaken. The selected section contains several tephra layers, which constrains the timing of deposition to MIS 13. Stable isotopes (oxygen and carbon) and element content were tentatively interpreted as linked to climatic changes giving interesting results for this poorly studied interval

Chitosan nanoparticles loaded with the antimicrobial peptide temporin B exert a long-term antibacterial activity in vitro against clinical isolates of Staphylococcus epidermidis

Nowadays, the alarming rise in multidrug-resistant microorganisms urgently demands for suitable alternatives to current antibiotics. In this regard, antimicrobial peptides (AMPs) have received growing interest due to their broad spectrum of activities, potent antimicrobial properties, unique mechanisms of action, and low tendency to induce resistance. However, their pharmaceutical development is hampered by potential toxicity, relatively low stability and manufacturing costs. In the present study, we tested the hypothesis that the encapsulation of the frog-skin derived AMP temporin B (TB) into chitosan nanoparticles (CS-NPs) could increase peptide's antibacterial activity, while reducing its toxic potential. TB-loaded CS-NPs with good dimensional features were prepared, based on the ionotropic gelation between CS and sodium tripolyphosphate. The encapsulation efficiency of TB in the formulation was up to 75%. Release kinetic studies highlighted a linear release of the peptide from the nanocarrier, in the adopted experimental conditions. Interestingly, the encapsulation of TB in CS-NPs demonstrated to reduce significantly the peptide's cytotoxicity against mammalian cells. Additionally, the nanocarrier evidenced a sustained antibacterial action against various strains of Staphylococcus epidermidis for at least 4 days, with up to 4-log reduction in the number of viable bacteria compared to plain CS-NPs at the end of the observational period. Of note, the antimicrobial evaluation tests demonstrated that while the intrinsic antimicrobial activity of CS ensured a "burst" effect, the gradual release of TB further reduced the viable bacterial count, preventing the regrowth of the residual cells and ensuring a long-lasting antibacterial effect. The developed nanocarrier is eligible for the administration of several AMPs of therapeutic interest with physical-chemical characteristics analog to those of TB

Amphiphilic pentablock copolymers and their blends with PDMS for antibiofouling coatings

Well-defined amphiphilic pentablock copolymers Siy-(EGx-FAz)2 composed of polysiloxane (Si), polyethylene glycol (EG), and perfluorohexylethyl polyacrylate (FA) blocks are synthesized by ATRP of FA monomer starting from a difunctional bromo-terminated macroinitiator. Diblock copolymers EGx-FAz are also synthesized as model systems. The block copolymers are used, either alone or blended with a PDMS matrix in varied loadings, to prepare antibiofouling coatings. Angle-resolved XPS and contact angle measurements show that the coating surface is highly enriched in fluorine content but undergoes reconstruction after contact with water. Protein adsorption experiments with human serum albumin and calf serum highlight that diblock copolymers resist protein adhesion better than do pentablock copolymers. Blending of the pentablock copolymer with PDMS results in increased protein adsorption. By contrast, the PDMS-matrix coatings show high removal percentages of sporelings of the green fouling alga Ulva linz

Does salinity variation increase synergistic effects of triclosan and carbon nanotubes on Mytilus galloprovincialis? Responses on adult tissues and sperms

The use of carbon nanotubes (CNTs) is rapidly increasing and several scientific studies have addressed their toxicological properties. However, only a very small number of publications have deal with the interaction between CNTs and other molecules. Triclosan (TCS) is an antibacterial agent used in personal care and household products. Commonly detected in aquatic ecosystems, there is a strong evidence that aquatic biota is sensitive to this compound. Aside from emergent pollutants, aquatic organisms are continuously subjected to abiotic variations including salinities. Therefore, the main goal of the present study was to better understand how physio-chemical interactions of CNTs with TCS under different salinity levels (37, 28 and 19) affect the mussel species Mytilus galloprovincialis through the evaluation of biochemical alterations on gametes (sperms) and adult tissues, providing more ecologically relevant information on organisms' responses. The results showed toxicological effects in terms of sperm metabolic activity and intracellular reactive oxygen species production as well as cellular damage and alteration of metabolic capacity at the adult's stage when exposed to both contaminants acting alone and in combination, under tested salinities. Moreover, when the mussels were exposed to the combination of both contaminants, they showed major toxic impacts on both assessed biological levels (adult tissues and sperms) especially under control salinity. This suggests that toxicity upon mixture exposure compared to single-substance exposure may impair mussels' populations, affecting reproduction success and growth.publishe

Ricostruzione paleoclimatica del MIS 13, mediante analisi multi-proxy di sedimenti lacustri del Bacino del Mercure (Basilicata)

RIASSUNTO ANALITICO Lo scopo della presente tesi è stato effettuare una prima ricostruzione paleoclimatica del periodo corrispondente allo Stadio Isotopico Marino (MIS) 13, mediante analisi multi-proxy (% CaCO3, δ18O, δ13C, fluorescenza a raggi X, diffratometria a raggi X) di sedimenti lacustri provenienti dal Bacino del Mercure (Basilicata). La sezione composita di S. Ciriaco, oggetto dello studio, ha uno spessore totale di 21 m. Il passo di campionamento adottato è stato di 10 cm. Lungo la sezione sono presenti cinque livelli vulcanici (tefra), di cui due datati con metodo Ar/Ar (SC1 e SC5, Giaccio et al. 2014). Gli altri tre tefra (SC2, SC3 e SC4) sono stati correlati con livelli vulcanici studiati in altri siti. Il modello di età è realizzato con la datazione diretta dei due tefra (SC1 e SC5), con la correlazione del tefra SC5 ritrovato anche nel lago di Ohrid in Macedonia (Francke et al. 2016) e tramite l’allineamento della curva del contenuto di carbonio inorganico (TIC) di Ohrid con quella della % CaCO3 e δ18O del Bacino del Mercure, con l’assunzione che le variazioni di questi parametri risultassero da comuni forzanti climatici e fossero quindi in fase tra loro. La sezione S. Ciriaco è stata in questo modo costretta tra i 545 e i 493 ka. I dati di δ18O sono stati interpretati come legati all’ammontare delle precipitazioni, mentre la percentuale di CaCO3 nel sedimento è stata messa in relazione con la produttività primaria del lago. Le due curve mostrano andamenti simili ed evidenziano tra 545 ka a 520 ka una progressiva diminuzione dell’ammontare delle precipitazioni e della produttività primaria; tra 520 ka e 505 ka un minimo di ammontare delle precipitazioni e della produttività primaria; da 505 ka a 493 ka un aumento delle precipitazioni e una ripresa della produttività primaria. Gli altri proxies (composizione mineralogica e concentrazione degli elementi clastici) interpretati come legati all’apporto detritico, hanno risposto coerentemente con queste variazioni, con un aumento delle condizioni di erosione nel bacino nei periodi caratterizzati da minori precipitazioni e minore produttività primaria. Il confronto con altri records paleoclimatici ha permesso di attribuire questi tre intervalli ai sub-stages MIS 13a, MIS 13b e MIS 13c. ABSTRACT The purpose of this thesis has been a first paleoclimatic reconstruction of the period corresponding to the Marine Isotope Stage (MIS) 13, through multi-proxy analyses (% CaCO3, δ18O, δ13C, XRF and XRD) lacustrine sediments from the Mercure Basin (Basilicata). The sampled composite section of S. Ciriaco has a total depth of 21 m. The adopted sampling resolution was 10 cm. Along the section there are five volcanic layers (tephra), two of which were dated through Ar/Ar method (SC1 and SC5, Giaccio et al. 2014). The other three tephra layers (SC2, SC3 and SC4) have been correlated with volcanic layers found in other sites. The age model has been derived by direct dating of the two tephra (SC1 and SC5), together with a the correlation of the SC5 tephra found also in Lake Ohrid, Macedonia (Francke et al. 2016) and through the alignment of the inorganic carbon content curve (TIC) of Ohrid with the % CaCO3 and δ18O of the Mercure Basin, with the assumption that variations among these parameters may result from common climatic forcings and thus are in phase with each other. The section of S. Ciriaco has been constrained between 545 ka and 493 ka. The δ18O data have been interpreted as linked to the amount of precipitation, while % CaCO3 has been related to the primary productivity of the lake. The two curves show similar trends and highlight, between 545 – 520 ka a progressive decline of the amount of both precipitation and the primary productivity. Between 520 – 505 ka there is a minimum in both precipitation and primary productivity and between 505 – 493 ka there is an increase of precipitation together with a resumption of the primary productivity. The other proxies (mineralogical composition and concentration of clastic elements), were interpreted as linked to the detrital influx to the lake and appear to respond consistently with the other proxies, with an increase of the erosion conditions in the basin in periods characterized by both lowr precipitations and low primary productivity. The comparison with other paleoclimatic records has allowed the attribution of these three periods to be MIS 13a, MIS 13b and MIS 13c sub-stages

Additive manufacturing of star poly(ε-caprolactone) wet-spun scaffolds for bone tissue engineering applications

Three-dimensional fibrous scaffolds made of a three-arm star poly(ε-caprolactone) were developed by employing a novel computer-aided wet-spinning apparatus to precisely control the deposition pattern of an extruded polymeric solution as a filament into a coagulation bath. Star poly(ε-caprolactone)/hydroxyapatite composite scaffolds composed of fibres with a porous morphology both in the outer surface and in the cross section were successfully produced with a layer-by-layer approach achieving good reproducibility of the internal architecture and external shape. Changes in processing parameters were used to fabricate scaffolds with different architectural parameters in terms of average pore size in the xy-axes (from 190 to 297 µm) and in the z-axis (from 54 to 126 µm) and porosity (in the range of 20%–60%). Based on the mechanical characterization, processing variations and hydroxyapatite loading have an influence on scaffold compression properties. Cell cultures, using a murine pre-osteoblast cell line, had good cell responses in terms of proliferation and osteoblastic differentiation. Thus, this technique appears to be an effective method for producing customized polymeric scaffolds for bone tissue engineering applications