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A multilayer nanofibrous membrane consisting of a layer of polycaprolactone and one of physically cross-linked alginate-embedding ZnO nanoparticles is prepared via electrospinning technique as potential wound healing patches with drug delivery capabilities. A washing-cross-linking protocol is developed to obtain stable materials at the same time removing poly(ethylene oxide), which was used here as a cospinning agent for alginate, without interfering with the membrane's peculiar nanofibrous structure. The mechanical behavior of the samples is assessed via a uniaxial tensile test showing appropriate resistance and manageability together with a good thermal stability as proved via thermogravimetric analysis. The polycaprolactone external layer enriches the samples with good liquid-repellent properties, whereas the alginate layer is able to promote tissue regeneration owing to its capability to promote cell viability and allow exudate removal and gas exchanges. Moreover, using methylene blue and methyl orange as model molecules, promising drug delivery abilities are observed for the mats. Indeed, depending on the nature and on the dye-loading concentration, the release kinetic can be easily tuned to obtain a slow controlled or a fast burst release. Consequently, the proposed alginate-polycaprolactone membrane represents a promising class of innovative, simple, and cost-effective wound healing patches appropriate for large-scale production.

Mark–Houwink parameters are determined for sodium alginate with low (SA LV) and medium (SA MV) molecular mass via a rheological approach. Firstly, salt screening concentration and polyelectrolyte nature of the polymers are investigated. Despite both alginates behaving as neutral polymer in θ solvent, differences are observed between them with the strong associative nature of SA MV highlighted by an abnormal high viscosity concentration dependence compared with the predicted values. The polysaccharide-specific hydrodynamic volume (i.e., intrinsic viscosity) is determined via Fedors approach, which is proved to provide accurate results applicable to a wide concentration range. A viscosity–molecular mass–concentration relationship is finally derived to calculate Mark–Houwink parameters via a non-linear regression according to Kulicke equation; the obtained values are consistent with those reported in literature, confirming the semi-flexible nature of SA in the investigated environment and proving the effectiveness of the proposed approach for polyelectrolytes with added salt ions.

Polysaccharide-based composites embedding silver nanoparticles (AgNPs) represent a promising alternative to common antimicrobial materials because of the effective, broad-spectrum biocidal properties of AgNPs combined with the biocompatibility and environmental safety of the naturally occurring polymeric component. In this work, AgNPs stabilized with alginate chains (Alg@AgNPs) were successfully synthesized in situ within the polysaccharide solution through a wet chemical approach carried out at different concentrations of the silver salt precursor. Once obtained, the aqueous suspensions were electrospun to prepare non-woven membranes, showing a homogeneous nanostructured texture (with fiber diameter between 100 and 150 nm), which was found to be influenced by the size (between 20 and 35 nm) of the embedded metal nanoparticles. The biocidal potential of the nanocomposite mats was preliminarily tested against Gram-negative E. coli. The results showed that the antimicrobial response of the investigated samples occurred within a day of incubation and can be observed for AgNPs content in the polysaccharide fibers far below the nanomolar regime.

The present review discusses the use of cyclodextrins and their derivatives to prepare electrospun nanofibers with specific features. Cyclodextrins, owing to their unique capability to form inclusion complexes with hydrophobic and volatile molecules, can indeed facilitate the encapsulation of bioactive compounds in electrospun nanofibers allowing fast-dissolving products for food, biomedical, and pharmaceutical purposes, filtering materials for wastewater and air purification, as well as a variety of other technological applications. Additionally, cyclodextrins can improve the processability of naturally occurring biopolymers helping the fabrication of "green" materials with a strong industrial relevance. Hence, this review provides a comprehensive state-of-the-art of different cyclodextrins-based nanofibers including those made of pure cyclodextrins, of polycyclodextrins, and those made of natural biopolymer functionalized with cyclodextrins. To this end, the advantages and disadvantages of such approaches and their possible applications are investigated along with the current limitations in the exploitation of electrospinning at the industrial level.

Poly(vinyl alcohol) nanofibrous mats containing ad hoc synthesized gold nanostructures were prepared via a single-step electrospinning procedure and investigated as a novel composite platform with several potential applications. Specifically, the effect of differently shaped and sized gold nanostructures on the resulting mat physical-chemical properties was investigated. In detail, nearly spherical nanoparticles and nanorods were first synthesized through a chemical reduction of gold precursors in water by using (hexadecyl)trimethylammonium bromide as the stabilizing agent. These nanostructures were then dispersed in poly(vinyl alcohol) aqueous solutions to prepare nanofibrous mats, which were then stabilized via a humble thermal treatment able to enhance their thermal stability and water resistance. Remarkably, the nanostructure type was proven to influence the mesh morphology, with the small spherical nanoparticles and the large nanorods leading to thinner well defined or bigger defect-rich nanofibers, respectively. Finally, the good mechanical properties shown by the prepared composite mats suggest their ease of handleability thereby opening new perspective applications.

Alginate-based hydrogels can be obtained by the simple addition of bivalent ions to aqueous polysaccharide solutions without the use of toxic chemicals; however, the hydrogels prepared by this way result inhomogeneous and irreproducible due to the extremely fast crosslinking reaction. To overcome such limitations, in the present work a novel preparation approach is proposed and optimized; the method is based on the use of agar moulds rich of bivalent ions as diffusing system to modulate the release of Ca 2+ , Sr 2+ , and Ba 2+ cations in order to guarantee a better control of the crosslinking process. A full factorial experimental design was applied to assess the effects and the mutual interactions of three selected parameters (sodium alginate concentration, crosslinking agent concentration within the agar moulds, crosslinking time) on the gelation process. The swelling and mechanical properties of the prepared hydrogels were investigated both in deionized water and in a saline environment; furthermore, the hydrogels were characterized by means of thermogravimetric analysis and field-emission scanning electron microscopy. The obtained results demonstrated that both the experimental variables and the environmental conditions have a significant influence on the structure and the performances of the resulting hydrogels. In particular, the use of high polymer concentration and crosslinking agent amount leads to strong hydrogels corresponding to a superior crosslinking degree; more in detail, Ba 2+ ions show a great affinity for alginate leading to the hydrogels with the highest mechanical properties. Moreover, the ion-exchange occurring in saline environment seems to strongly reduce the effective crosslinking degree of alginate hydrogels with a consequential loss of mechanical properties and stability. The collected data were finally elaborated through statistical analysis combined with response surface methodology to develop theoretical models successfully able to correlate the crosslinking degree to the experimental conditions, thus opening the way of designing and fabricating alginate-based hydrogels with tailored morphology and mechanical properties.

In this work, a nanocomposite material based on alginate (Alg) and silver nanoparticles (AgNPs) was prepared by the synthesis “in situ” of the metal cores in the polymer solution through a wet, bottom-up approach. The formation of AgNPs within the alginate matrix (Alg–Ag) was confirmed by spectroscopic and morphological investigation. The nanocomposite material was then employed in combination with poly(ethylene oxide) for the production of crosslinked alginate membranes by electrospinning technique, following a simple and effective protocol optimized to obtain nano- to microscaled fibers. Field emission scanning electron microscopy (FESEM) studies on the composite membranes indicated that AgNPs of slightly increased dimensions are well distributed in the electrospun mats, thus proving that the electrospinning process does not significantly alter the morphology of the metal nanofillers and can be successfully adopted for the fabrication of nanofibers. In view of their potential applications in biomedical fields and food industry as antibacterial material, the nanocomposite mats were tested against thermal and UV sterilization, anti-mold treatment (NaClO) and environmental changes (pH) and their stability was monitored by means of thermogravimetric (TGA) and morphological (FESEM) techniques.

Chitosan nanofibrous membranes are prepared via an electrospinning technique and explored as potential wound healing patches. In particular, the effect of a physical or chemical crosslinking treatment on the mat morphological, mechanical, water-related, and biological properties is deeply evaluated. The use of phosphate ions (i.e., physical crosslinking) allows us to obtain smooth and highly homogenous nanofibers with an average size of 190 nm, whereas the use of ethylene glycol diglycidyl ether (i.e., chemical crosslinking) leads to rougher, partially coalesced, and bigger nanofibers with an average dimension of 270 nm. Additionally, the physically crosslinked mats show enhanced mechanical performances, as well as greater water vapour permeability and hydrophilicity, with respect to the chemically crosslinked ones. Above all, cell adhesion and cytotoxicity experiments demonstrate that the use of phosphate ions as crosslinkers significantly improves the capability of chitosan mats to promote cell viability owing to their higher biocompatibility. Moreover, tuneable drug delivery properties are achieved for the physically crosslinked mats by a simple post-processing impregnation methodology, thereby indicating the possibility to enrich the prepared membranes with unique features. The results prove that the proposed approach may lead to the preparation of cheap, biocompatible, and efficient chitosan-based nanofibers for biomedical and pharmaceutical applications.

This paper deals with the interfacial adhesion properties of Ti-6Al-4V alloy substrates, prepared by using different treatment protocols selected on the basis of their different effectiveness, and bonded using a structural, high-strength epoxy adhesive. The alternative pre-bonding treatments were sodium hydroxide anodization and low-pressure-plasma treatment, the effects of which were compared to that of a base preparation via solvent degreasing of the substrates’ surface. The treated surfaces were joined according to standard protocols, and then tested for shear strength. The mechanical results were then correlated to surface characteristics of the substrates such as oxidation state and wettability. Parallel scanning Kelvin-probe measurements allowed us to focus our attention on the possible role of the electrical properties of the substrates. We observed that each treatment entails different behavior of the electrical potential of the surface, which correlates with the mechanical strength of the joints. The results suggest that an evaluation of the surface potential of titanium-alloy substrates might be a promising, indicative supplementary parameter for the evaluation of their pre-bonding surface conditions, allowing correlations with presence/absence of an oxide layer at the resin-substrate interface.

To assess the influence of rheological properties of an artificial vitreous (AV) on the performance of double-blade (DB) and single-blade (SB) guillotine vitreous cutters, with 23-, 25-, and 27-gauge (G) probes. We evaluate the aspiration flow rate, using an optical method, based on image processing. Experiments are conducted using ten viscoelastic vitreous phantoms, with different properties that are measured with rheological tests. Aspiration rate strongly varies with fluid properties. Regardless of cutter geometry and operational conditions, the flow rate significantly decreases as vitreous viscosity and elasticity increase. All tested vitreous probes are very sensitive to changes in fluid rheology. SB cutters produce smaller flow rates compared with DB ones of the same caliber; however, they are less sensitive to fluid properties at low aspiration pressures. The use of vitreous substitutes for test performance guarantees comparability between flow rate results achieved with different vitrectomy systems operating in different media. This outcome is further confirmed by the low values of estimated flow rate relative errors.

Alginate-based electrospun nanofibers prepared via electrospinning technique represent a class of materials with promising applications in the biomedical and pharmaceutical industries. However, to date, the effect of alginate molecular mass and block composition on the biological response of such systems remains to some extent unclear. As such, in the present work, three alginates (i.e., M.pyr, L.hyp, A.nod) with different molecular features are employed to prepare nanofibers whose ability to promote cell adhesion is explored by using both skin and bone cell lines. Initially, a preliminary investigation of the raw materials is carried out via rheological and zeta-potential measurements to determine the different grade of polyelectrolyte behaviour of the alginate samples. Specifically, both the molecular mass and block composition are found to be important factors affecting the alginate response, with long chains and a predominance of guluronic moieties leading to a marked polyelectrolyte nature (i.e., lower dependence of the solution viscosity upon the polymer concentration). Subsequently, physically crosslinked alginate nanofibrous mats are first morphologically characterized via both scanning electron and atomic force microscopy, which show a homogenous and defect-free structure, and their biological response is then evaluated. Noticeably, fibroblast and keratinocyte cell lines do not show significant differences in terms of cell adhesion on the three mats (i.e., 30-40% and 10-20% with respect to the seeded cells, respectively), with the formers presenting a greater affinity toward the alginate-based nanofibers. Conversely, both the investigated osteoblast cells are characterized by a distinct behaviour depending on the alginate type. Specifically, polysaccharide samples with an evident polyelectrolyte nature are found to better promote cell viability (i.e., cell adhesion in the range 15-36% with respect to seeded cells) compared to the ones displaying a nearly neutral behaviour (i.e., cell adhesion in the range 5-25% with respect to seeded cells). Therefore, the obtained results, despite being preliminary, suggest that the alginate type (i.e., molecular structure properties) may play a topical role in conditioning the efficiency of healing patches for bone reparation, but it has a negligible effect in the case of skin regeneration.

Alginate-based membranes embedding zinc oxide nanoparticles are prepared via electrospinning and exploited as biosorbent materials. The mats exhibit a uniform texture characterized by the presence of nanofibers with an average diameter of 100 nm and interconnected voids of 140 nm average size. UV–vis spectrophotometric tests were performed to evaluate the membrane uptake/release performances by employing aqueous solutions of Methylene Blue (MB) and Congo Red (CR), chosen as model probes of basic and acidic type, respectively. Isotherm kinetics and equilibrium data are fitted with theoretical models to acquire information on the process mechanisms and rates. At low dosage, the mats show comparable adsorption capacity toward both dyes with limited selectivity for the cationic one suggesting that the process is conditioned by the macroporous structure of the membranes. Moreover, a good reusability for achieved for MB after simple washing steps in deionized water. Remarkably, the desorption efficacy under physiological-like conditions turn out to be very high for MB but reduced for CR indicating that the release process is affected by ionic interactions. Based on the results, the electrospun membranes reveal potential as innovative, low-cost, and versatile absorbent platforms to be used in drug delivery applications as well as in purification processes.

Due to its high toxicity, Pb2+ pollution is a serious threat for human health and environments. However, in situ real-time detection of Pb2+ pollution is difficult and laboratory instruments are usually required. Then, the possibility to monitor water quality without laboratory instruments could lead to the extensive assessment of polluted water sources, especially in rural environments and developing countries where large lead concentrations are often found in surface water. Consequently, new simple colorimetric sensors are highly interesting in the field. In this work we report for the first time disposable polymer planar 1D photonic crystals made of poly (N-vinylcarbazole) as high refractive index medium and sodium alginate as low refractive index and active medium for the detection of Pb2+ in water. The detection relies on the ionic exchange occurring into the alginate matrix. This process effectively induces a physical cross-linking phenomenon, which inhibits water solubilization of the polymer. In turn, this affects the spectral response of the planar 1D photonic crystals modifying its color.

Chitosan-based membranes were prepared via electrospinning technique using a low concentrated acetic acid solution as solvent and poly(ethylene oxide) as co-spinning agent. Different solutions were rheologically characterized and increasing the solution viscosity was found to correspond to a better-defined morphology. The membranes were first subjected to a coagulation process with different baths in order to stabilize chitosan and the mats were found not able to withstand a strongly basic environment. Subsequently, a physical and a chemical crosslinking approach were separately optimized to obtain stable mats whose composition was assessed via thermogravimetric and spectroscopic techniques, proving in both cases the elimination of the co-spinning agent. Above all, the ionically crosslinked mats represent a class of extremely promising biomedical products being probably highly biocompatible and characterized by thin and homogenous nanofibers with a diameter of 200 nm, thus showing the ideal structure to foster cell viability.

Polyvinylpyrrolidone electrospun membranes characterized by randomly, partially, or almost completely oriented nanofibers are prepared using a drum collector in static (i.e., 0 rpm) or rotating (i.e., 250 rpm or 500 rpm) configuration. Besides a progressive alignment alongside the tangential speed direction, the nanofibers show a dimension increasing with the collector rotating speed in the range 410&ndash, 570 nm. A novel design of experiment approach based on a face-centred central composite design is employed to describe membrane mechanical properties using the computation of mathematical models and their visualization via response surface methodology. The results demonstrate the anisotropic nature of the fibre-oriented membranes with Young&rsquo, s modulus values of 165 MPa and 71 MPa parallelly and perpendicularly to the alignment direction, respectively. Above all, the proposed approach is proved to be a promising tool from an industrial point of view to prepare electrospun membranes with a tailored mechanical response by simply controlling the collector speed.

The effects of varying percentage loadings of morpholine pre-treated cellulose nanofibrils (MCNF) and carboxymethylated cellulose nanofibrils (CMCNF) on the aqueous swelling, compressive modulus and viscoelastic properties of calcium-ion-crosslinked alginate hydrogels were investigated. In addition, the pore structures of hydrogels with the highest compressive modulus were studied. The incorporation of 5 wt. % MCNF resulted in a slightly reduced aqueous swelling, a 36% increase in compressive modulus and a layered pore structure when compared with the neat alginate hydrogel. On the other hand, the addition of CMCNF at the same loading led to a slightly improved aqueous swelling, an increase in compressive modulus (17%) and high porosity. Further increases in CNF loadings did not result in significant increase in material properties. The alginate/CNF composite materials have potentials to be used in applications where good swelling and mechanical robustness are required.

Epoxy resins, heavily loaded with fillers, are used as fairing compounds in coating systems to fill superficial imperfections and protect the hull of yachts and ships; they are complex composite materials whose final performance can be heavily affected by the conditions of application. In this paper the curing process of an innovative formulation was studied in function of the temperature and humidity, in order to evaluate how these environmental parameters influence the reaction evolution and gain further insight into the reaction mechanism. The study of the curing process was carried out by thermogravimetric analysis, differential calorimetric analysis and FT-IR spectroscopy. From the thermal analysis the obtained crosslink degree ranged between 92 and 99%, at 10 °C and 25 °C respectively. The samples cured at 25 °C reached the maximum curing degree in one week independently from the humidity. The samples cured at lower temperature (10 °C), even after two weeks, did not reach the complete crosslinking. On the other side, it was evident that the humidity did not influence the curing at 25 °C, while it had a slight effect at lower temperature (10 °C). Results from FTIR spectroscopy at 25 °C evidenced changes in the bands characterizing the two components of the resin during the curing reaction, in particular the disappearance of the oxirane ring band.

In the present work, alginate-based mats with and without ZnO nanoparticles were prepared via an electrospinning technique and subjected to a washing-cross-linking process to obtain highly stable products characterized by thin and homogeneous nanofibers with a diameter of 100 ± 30 nm. Using a commercial collagen product as control, the biological response of the prepared mats was carefully evaluated with particular attention paid to the influence of the used cross-linking agent (Ca2+, Sr2+, or Ba2+ ions) and to the presence of nanofillers. Fibroblast and keratinocyte cultures successfully proved the safety of the prepared alginate-based mats, whereas ZnO nanoparticles were found to provide strong antibacteriostatic and antibacterial properties; above all, the strontium- and barium-cross-linked samples showed performances in terms of cell adhesion and growth very similar to those of the commercial collagen membrane despite them showing a significantly lower protein adsorption. Moreover, the mechanical and water-related properties of the strontium-cross-linked mats embedding ZnO nanoparticles were proven to be similar to those of human skin (i.e., Young modulus of 470 MPa and water vapor permeability of 3.8 × 10-12 g/m Pa s), thus proving the ability of the prepared mats to be able to endure considerable stress, maintaining at the same time the fundamental ability to remove exudates. Taking into account the obtained results, the proposed alginate-based products could lead to harmless and affordable surgical patches and wound dressing membranes with a simpler and safer production procedure than the commonly employed animal collagen-derived systems.

Collagen filaments derived from the two marine demosponges Ircinia oros and Sarcotragus foetidus were for the first time isolated, biochemically characterised and tested for their potential use in regenerative medicine. SDS-PAGE of isolated filaments revealed a main collagen subunit band of 130 kDa in both of the samples under study. DSC analysis on 2D membranes produced with collagenous sponge filaments showed higher thermal stability than commercial mammalian-derived collagen membranes. Dynamic mechanical and thermal analysis attested that the membranes obtained from filaments of S. foetidus were more resistant and stable at the rising temperature, compared to the ones derived from filaments of I. oros. Moreover, the former has higher stability in saline and in collagenase solutions and evident antioxidant activity. Conversely, their water binding capacity results were lower than that of membranes obtained from I. oros. Adhesion and proliferation tests using L929 fibroblasts and HaCaT keratinocytes resulted in a remarkable biocompatibility of both developed membrane models, and gene expression analysis showed an evident up-regulation of ECM-related genes. Finally, membranes from I. oros significantly increased type I collagen gene expression and its release in the culture medium. The findings here reported strongly suggest the biotechnological potential of these collagenous structures of poriferan origin as scaffolds for wound healing.

In the present work, different sodium alginates were used to prepare nanofibrous mats by means of electrospinning technique. Firstly, a molecular characterization of each sample was carried out: the molecular mass and the composition, i.e. mannuronic/guluronic acid ratio, were determined using the Mark–Houwink–Sakurada relation and FTIR spectroscopy, respectively. Afterwards, the polyelectrolyte nature and the characteristic concentration regimes of each alginate were studied through rheological tests. The results indicated that both the molecular mass and the composition strongly influence the properties of the polymer in solution; in particular, long chains and the predominance of guluronic moiety lead to a marked polyelectrolyte behaviour. Subsequently, in order to obtain a good spinnability, polyethylene oxide and Triton X-100 were added to alginate-based solutions. The resulting solutions were carefully characterized by a rheological point of view; the viscosity, viscoelasticity, thixotropy and thermal stability were investigated and correlated with their capability of being electrospun. Two different set-ups were used for electrospinning: one consisted in a dry collector and the other one in a wet collector (immersed in a collecting solution). The morphology of the membranes was characterized through scanning electron microscopy; moreover, thermogravimetric analysis was performed in order to study the final composition and the thermal degradation. The preliminary results indicated that the membrane obtained using guluronic-rich alginate and the wet-collector system is composed of only sodium alginate and characterized by thin fibres and a high porosity, which could make it suitable for pharmaceutical and biomedical applications.

TiO2 was prepared via sol–gel synthesis, and in order to obtain crystallized anatase in a colloidal suspension, it was subjected to a hydrothermal process in the presence of a minimum amount of nanoparticles, which acted as nucleation seeds. Concurrently, high-pH sol–gel syntheses were performed with the increase in NH3 solutions as a comparison for the samples’ activity. Polydimethylsiloxane was chosen as supporting material for the TiO2 nanoparticles for its high surface area and its stability against catalyst’s photoactivity. They were both processed with the electrospinning technique: It was possible to disperse titania among PDMS fibers and to obtain detachable polymeric membranes with the appearance of white soft sheets. These membranes show antibacterial activity under fluorescent light, and thus, they may be used as a film for several kinds of surfaces. The synthesized samples were controlled and characterized by means of rheological measurements, scanning electron microscopy images together with EDS maps, differential scanning calorimetry analyses, diffuse reflectance spectra for energy gap (Egap) calculations and recycling photocatalytic experiments, while Escherichia Coli inactivation gave evidence of the antibacterial activity.

In this paper, raw hemp fibres were used to reinforce a commercial biopolyester, namely poly(1,4-butylene adipate-co-terephthalate), to achieve eco-composite materials. To promote the adhesion between the polyester matrix and the fibrous reinforcement, chemical modification of fibres surface with coupling agents was accomplished. Usually, the grafting of coupling molecules is carried out involving high amount of solvents. Here, in a general approach of an environmental sustainability, uncut, combed and slightly stretched hemp fibres were treated with a green process based on a novel soft plasma jet device (developed by Nadir Srl). This technique activates the fibres surface and, at the same time, allows the deposition of reactive monomers as coupling agents. Three different monomers were investigated: methyl methacrylate (MMA), (3-aminopropyl)triethoxysilane (APTES) and (3-glycidyloxypropyl)trimethoxysilane. Unmodified and surface-modified fibres were characterized and compared in terms of thermal behaviour and morphological features. Long-fibre eco-composites were then prepared by different compression moulding procedures and characterized by thermal, morphological and dynamic mechanical analysis. Experimental evidences indicated that the cold plasma deposition/grafting treatment was successfully carried out; the composite with the best mechanical performance resulted that obtained by using APTES as coupling agent.

Non-ionic polysaccharides, mainly cellulose ethers, have been extensively studied as thickeners in paint formulation. Their mechanism of interaction with the surrounding system is well known and, due to their easy dissolution properties and availability on the market, they are the most used thickening agents. On the other hand, ionic polysaccharides, having possible interaction with the components of the formulation, are less used. In this work, the role of an anionic polysaccharide, sodium alginate (SA), as a thickener, was investigated in a typical wall paint formulation by evaluating its interaction with the principal components of the formulation: water, binder, pigment and extender. Rheology and FTIR spectroscopy were used to evaluate the occurrence of chemical bonds between the polysaccharide chains and the surrounding system. Contemplating the results, sodium alginate, depending on its molecular weight, M ¯ w , and concentration, turns out to be a suitable thickener for wall paint formulations. In particular, the possibility of building-up a network due to the presence of entanglements, and the interaction with water molecules and extender, demonstrated that the formulation prepared with 0.2 wt. % of a medium M ¯ w alginate was the most promising one. On the other hand, low M ¯ w alginate exhibited a weaker gel structure and only if present at 0.4 wt. % was appropriate concentration for a ready-to-use product.

The molecular mass of two sodium alginates with the same composition but different chain length is reduced via a simple ultrasonic treatment and monitored by rheological measurements. The polymer molecular mass decreases until a lower limiting value of 100 kg/mol is reached, with the degradation occurring via a mid-point-chain kinetic consisting into the breakage of the glycosidic bonds towards the middle of the macromolecules. The evaluation of the concentration regimes (i.e. viscosity dependence upon the polymer concentration) demonstrates that short chains are characterized by higher critical concentrations and lower scaling factors, most likely owing to their poor ability to form entanglements. Nevertheless, the typical behaviour of neutral polymer in θ solvent is observed independently of the alginate molecular mass. The viscosity temperature dependence of the investigated solutions obeys Arrhenius law in a wide temperature range. Additionally, the flow activation energy is observed to follow a linear relationship with the polymer molecular mass with values of 26.2 kJ/mol for the longest chains and 18.2 kJ/mol for the shortest ones. Consequently, ultrasonic treatment is here proved to be extremely efficient to reduce the molecular mass of alginate, thus representing a fast, safe and cost-effective approach to obtain materials with tailored properties.

Different additives based on Na oleate, Na oleate – Ca stearate and Al stearate were used in two different quantities (0.15 %w/w and 0.30 %w/w of the solid amount) to enhance the waterproofing effect of mortars. From capillary water absorption test, Na oleate showed the better performance with a reduction of water absorbed of 86% in comparison with the reference mortar. The microstructure showed the presence of microcavities ranging between 0.01 mm and 0.2 mm, due to air bubbles trapped during the mortar preparation for the surfactant effect of Na oleate. The presence of a higher amount of pores (210 mm3/g vs. 175 mm3/g) was confirmed by the Hg porosimetry. Moreover a reduction of the carbonation rate for the presence of additive was verified.

Alginate based materials have become an important class of products in many fields from the pharmaceutical industry to tissue engineering, because of their ability to create stimuli responsive hydrogels. We present a new technical approach for obtaining a controlled gelling process, based on the quantities of Ca(2+) rich alginate micro-beads added as crosslinkers. The gels have been evaluated in light of the amount of Ca(2+) added to the alginate solution, and in light of the different dimensions of the micro-beads, using rheological measurements to assess the variation in the storage modulus (G'), loss modulus (G'') and complex viscosity (η(*)) as well as swelling and deswelling tests. The methodology was developed to obtain a material with specific characteristics for application in the field of conservation. The material had to be able to create a stable gel after being applied on the artwork surface and to confine the solvent action at the interface during cleaning operations.

Agar is a natural polymer commonly used in various fields of application ranging from cosmetics to the food industry. In particular, for over forty years agar gels have been used in the field of conservation of Cultural Heritage where they are considered as one of the main well-performing tools in cleaning procedures. In the present work, the relation between the chemical composition and the mechanical strength of four different agar hydrogels was evaluated by comparing the results obtained via pyrolysis-gas chromatography/mass spectrometry and rheological characterization. Agar composition was studied by means of a pyrolysis-gas chromatography/mass spectrometry approach in order to differentiate the anhydrous, galactose and glucose units. Pristine agar gels, gels after double annealing, and gels with and without chelating agent were studied by means of amplitude, frequency and time sweep rheological tests to evaluate all the preparation approaches commonly used by conservators, also taking into account changes in the transparency via UV–vis spectroscopy. A high percentage of anhydrous units in the polymer backbone was found to provide superior mechanical stiffness to the pristine hydrogels, even if it did not seem to affect their long-term stability. The annealing process significantly improved the rheological response of galactose-rich agar hydrogels being able to promote the establishment of additional crosslinking points, whereas the additive presence showed to improve the hydrogel stiffness owing to a more structured polymer network. Moreover, the progressive reduction of the impurities and/or network defects within the hydrogels occurring due to the annealing process slightly increased the transparency of the hydrogels, which is an important aspect for applications in the conservation of Cultural Heritage.

In the present work alginate-based nanofibrous membranes embedding zinc oxide nanoparticles (ZnO-NPs) were prepared via electrospinning technique. ZnO-NPs were synthesized by means of a "green" sol-gel method by using alginate itself as stabilizing agent and characterized through UV-vis spectroscopy, thermogravimetric and morphological analysis. Formulations containing sodium alginate, poly(ethylene oxide) and ZnO-NPs were rheologically studied to identify the most suitable ones to be electrospun; alginate molecular structure played an important role on the solution spinnability due to the polysaccharide capability to establish electrostatic interactions and hydrogen bonds with ZnO-NPs. An innovative washing-crosslinking protocol was developed to obtain stable products which composition was assessed using Fourier Transform InfraRed spectroscopy and thermogravimetric analysis. Morphological investigation combined with EDX spectroscopy proved the obtained mats were highly porous and composed by thin homogenous nanofibers with a good distribution of the used nanofillers, thus representing potential products for several purposes (e.g. biomedical, pharmaceutical and environmental applications).

Collagen is involved in the formation of complex fibrillar networks, providing the structural integrity of tissues. Its low immunogenicity and mechanical properties make this molecule a biomaterial that is extremely suitable for tissue engineering and regenerative medicine (TERM) strategies in human health issues. Here, for the first time, we performed a thorough screening of four different methods to obtain sponge collagenous fibrillar suspensions (FSs) from C. reniformis demosponge, which were then chemically, physically, and biologically characterized, in terms of protein, collagen, and glycosaminoglycans content, viscous properties, biocompatibility, and antioxidant activity. These four FSs were then tested for their capability to generate crosslinked or not thin sponge collagenous membranes (SCMs) that are suitable for TERM purposes. Two types of FSs, of the four tested, were able to generate SCMs, either from crosslinking or not, and showed good mechanical properties, enzymatic degradation resistance, water binding capacity, antioxidant activity, and biocompatibility on both fibroblast and keratinocyte cell cultures. Finally, our results demonstrate that it is possible to adapt the extraction procedure in order to alternatively improve the mechanical properties or the antioxidant performances of the derived biomaterial, depending on the application requirements, thanks to the versatility of C. reniformis extracellular matrix extracts.

Hyaluronic acid (HA) solutions represent an important class of biomedical products, mostly used in viscosupplementation of joints and as fillers. In the present work the hydrodynamic and rheological properties of hyaluronic acid, of differing MW(90-4000 kDa), in physiological saline were investigated. Firstly, the effective conformation taken by the polymer chains was studied using dynamic light scattering. It was observed that they behaved like random coils which dimension is higher increasing the molecular weight of the material. Secondly, combining a novel microrheological technique, based on the dynamic light scattering of tracer particles, with conventional rheometry, it was possible to study in which way the molecular weight and the concentration of the polymer influence the storage modulus (G’), loss modulus (G”) and complex viscosity (η*) of its solutions, over an extended frequency range (typically 0.01-10000 Hz). This extended characterization allowed determination of the mesh size ξ of the physical network, created by the entangled polymer chains. Calculated mesh sizes in the range 200-700 nm were observed, demonstrating the possibility to use these systems as injectable carriers of biomolecules with an appropriate dimension.

The on-site assessment of the effectiveness and durability of conservation treatments have several drawbacks which have their origin in the demands of the owners (both from the aesthetical point of view and with the need to conclude the restoration as soon as possible), and in the requirements of the restorer related with the logistic of the yard and with the need to satisfy the owner demands. These aspects are often in conflict with the methodological approach used in the scientific framework for evaluate the performance of applied treatments. The aims of this paper is to suggest practical solutions, capable to overcome the previous problems in the assessment of the efficiency of the consolidating and protective treatments applied on the marly limestone ashlars of the Abbey of San Fruttuoso di Capodimonte (Genoa, Italy). The abbey is located at the bottom of a bay few meters from the see, therefore strongly exposed to the action of the marine aerosol and wave erosion. The consolidation and protection of the marly limestone building material was performed by testing several products both inorganic and organic. Preliminary tests were performed on laboratory samples. Afterwards, the same products were applied on selected ashlars of the facade in order to study their performance in a real condition. The products were ethyl silicate, ethyl silicate with polysiloxane, litium silicate, nanosilica, ammonium oxalate, ammonium phosphate, silane/siloxane, fluorelastomers and acrylic polymers and acrylic/siloxane. The study of the effect of the treatments on the stone samples was performed by non-destructive and micro-destructive methods, and an assessment procedure has been proposed.