Roberto Nisticò

Hernia-repair prosthetic devices functionalised with chitosan and ciprofloxacin coating: Controlled release and antibacterial activity

Polypropylene nets are widely used as hernioplasty prostheses. The reproduction of bacteria within the net fibers intersections can occur after the application of the prosthesis causing infections. For this reason, bacteria have to be removed in the very early stage of surgical implantation. Activation of the prosthesis surface was done by an innovative oxidizing plasma treatment (APP-DBD) working under atmospheric conditions in order to favor the deposition of an antibacterial coating of chitosan (biocompatible carbohydrate) and ciprofloxacin (broad spectrum antibiotic). Two different coating mixtures were realised and the antibacterial properties of such functionalised nets were investigated, together with their effectiveness. Physico-chemical characterisations of meshes were carried out before and after functionalisation by SEM-EDS and infrared spectroscopy. The release of both chitosan and ciprofloxacin, under controlled experimental conditions, was followed respectively by colorimetric determination (using UV-Visible spectroscopy) and chromatographic analysis (using HPLC). In vitro tests allow verifying antimicrobial activity (inoculation of specimens in a Staphylococcus aureus suspension).

Biopolymers from Composted Biowaste as Stabilizers for the Synthesis of Spherical and Homogeneously Sized Silver Nanoparticles for Textile Applications on Natural Fibers

The use of bio-based substances (BBS) obtained from composted biowaste as stabilizers for the production of silver nanoparticles (AgNPs) in substitution to citrate is investigated herein, evaluating the functionalization of natural fibers for textile antibacterial applications. The results obtained evidenced that BBS can substitute citrate as reducing/stabilizing agent in the synthesis, inducing a geometrical control (in shape and size) of the AgNPs. Two different substrates were selected (wool and cotton) and two dip-coating deposition techniques investigated. The release of AgNPs from the supports in water was evaluated under two different experimental conditions: 1) soaking (static conditions) for 7 and 15 days, simulating the contact with sweat, and 2) centrifugation (dynamic conditions), simulating a washing machine treatment. A wide physicochemical characterization was carried out to evaluate the effects of BBS on the morphology and stability of AgNPs suspensions as well as the functionalization effectiveness.

Sustainable magnet-responsive nanomaterials for the removal of arsenic from contaminated water

In this study, chitosan and bio-based substances (BBS) obtained from composted biowaste were used as stabilizers for the synthesis of magnet-sensitive nanoparticles (NPs) via coprecipitation method. A pyrolysis treatment was carried out on both biopolymers at 550°C, and their consequent conversion into a carbon matrix was followed by means of different physicochemical characterization techniques (mainly FTIR spectroscopy and XRD), whereas magnetic properties were evaluated by magnetization curves. The prepared materials were tested in water remediation processes from arsenic (As) species (both inorganic and organic forms). These tests, explained by means of the most common adsorption models, evidenced that the best performances were reached by both materials obtained after pyrolysis treatments, pointing out the promising application of such magnet-sensitive materials as easy-recoverable tools for water purification treatments.

Magnetic materials and water treatments for a sustainable future

After a brief historical classification of the main discoveries related to magnetism, magnetic materials have been rationally ordered in a simple (and hopefully clear) organization. A great effort was realized in the description of the different synthetic approaches for the preparation of magnet-sensitive materials (in particular, focusing on iron oxides). The principal useful techniques for evaluating the magnetic properties in materials (namely, MFM and magnetization hysteresis) have been presented, providing useful examples in order to understand both the potentiality and limits of these characterization methods. Finally, the application of magnet-sensitive materials in water remediation processes has been provided, highlighting both advantages and disadvantages of their use compared to conventional treatments. In this context, the action mechanism and the possible integration of this class of materials into processes involving wastewater treatments are widely discussed, keeping an eye toward the future perspectives.

Study of the adhesive properties versus stability/aging of hernia repair meshes after deposition of RF activated plasma polymerized acrylic acid coating

In order to confer adhesive properties to commercial polypropylene (PP) meshes, a surface plasma-induced deposition of poly-(acrylic acid) (PPAA) is performed. Once biomaterials were functionalized, different post-deposition treatments (i.e. water washing and/or thermal treatments) were investigated with the aim of monitoring the coating degradation (and therefore the loss of adhesion) after 3months of aging in both humid/oxidant (air) and inert (nitrogen) atmospheres. A wide physicochemical characterization was carried out in order to evaluate the functionalization effectiveness and the adhesive coating homogeneity by means of static water drop shape analysis and several spectroscopies (namely, FTIR, UV-Visible and X-ray Photoemission Spectroscopy). The modification of the adhesion properties after post-deposition treatments as well as aging under different storage atmospheres were investigated by means of Atomic Force Microscopy (AFM) used in Force/Distance (F/D) mode. This technique confirms itself as a powerful tool for unveiling the surface adhesion capacity as well as the homogeneity of the functional coatings along the fibers. Results obtained evidenced that post-deposition treatments are mandatory in order to remove all oligomers produced during the plasma-treatment, whereas aging tests evidenced that these devices can be simply stored in presence of air for at least three months without a meaningful degradation of the original properties.

The hypersaline synthesis of titania: from powders to aerogels

High surface area mesoporous titania has been synthesized using ordinary salts (chlorides) for morphology control during the sol–gel process. Applying Ti-alkoxide (TTIP) as a titania precursor and a highly-concentrated hypersaline medium, different results have been obtained according to the dispersing medium selected. By working in an acid environment, the hypersaline medium controls the oxide network growth, since different salts (and different salts amount) influence the surface area, porosity, crystallinity and polymorphs rearrangement of the final material, favoring the formation of acicular-like rutile at mild conditions. Nevertheless, it has been verified that, according to the Hofmeister series, salting-in ions induce an increase in the titania surface area, going from 79 (for the reference, without any salts) up to 253 m2 g−1 (for the Li-templated titania). By working in alcoholic media, the hypersaline environment favors the gelification process and the formation of amorphous titania aerogels or highly-porous monoliths, according to the drying conditions selected (respectively supercritical CO2 or ambient pressure air drying). Two different alcoholic media (ethanol and 2-propanol) have been compared. Such salt-templated titania aerogels are mesoporous (with BET surface area comprised between 322 and 490 m2 g−1). Besides the surface area, even the pore volume and the pore size can be controlled by both the reaction medium and the drying step: in particular, air-dried monoliths are small mesoporous (BET surface area between 419 and 518 m2 g−1). Reference materials synthesized in alcoholic media without using any salts do not gelify (thus confirming the importance of the hypersaline medium), whereas titania particles precipitate, inducing aggregation into small mesoporous powders. In general, the hypersaline-mediated titania production seems to be an interesting chemical toolbox, sustainable, highly efficient and also potentially suitable for industrial scaling-up.

From biowaste to magnet-responsive materials for water remediation from polycyclic aromatic hydrocarbons

Composted urban biowaste-derived substances (BBS-GC) are used as carbon sources for the preparation of carbon-coated magnet-sensitive nanoparticles obtained via co-precipitation method and the subsequent thermal treatment at 550 °C under nitrogen atmosphere. A multitechnique approach has been applied to investigate the morphology, magnetic properties, phase composition, thermal stability of the obtained magnet-sensitive materials. In particular, pyrolysis-induced modifications affecting the BBS-GC/carbon shell were highlighted. The adsorption capacity of such bio-derivative magnetic materials for the removal of hydrophobic contaminants such as polycyclic aromatic hydrocarbons was evaluated in order to verify their potential application in wastewater remediation process. The promising results suggest their use as a new generation of magnet-responsive easily-recoverable adsorbents for water purification treatments.

Thermopressed binderless fiberboards from post-harvest tomato and maize plants

Post-harvest tomato plants were used to manufacture fireboards by thermopressing. Four plant materials were investigated: exhausted tomato plants ground to 5-10 mm (PHTr), tomato (PHT) and maize (PHM) plants ground to <0.5 mm, composted tomato plants (CPHT). These materials had significantly different chemical composition, which significantly influenced the fireboards mechanical properties. The PHM fireboards containing the highest amount hemicellulose and water soluble sugars, and the lowest minerals‘ amount, performed best. The data allow estimating the role of each plant proximate in determining board mechanical behavior. Moreover, the findings of the work prospect a desirable integration of municipal and agriculture biowastes as a step forward toward the valorization of renewable organic matter and the realization of the zero waste objective.

Reactive Hypersaline Route: One-Pot Synthesis of Porous Photoactive Nanocomposites

Herein, porous photoactive nanocomposites are prepared by a simple one-pot synthesis approach using a salt and aqueous media. Within this reactive hypersaline route, the salt not only serves in the structuring of the composite but also becomes an integral active part of it. Here, the addition of sodium thiocyanate to a titania precursor guides, on the one hand, the formation of needle-shaped nanoparticles and, on the other hand, forms yellow compound isoperthiocyanic acid, which is homogeneously incorporated into the porous nanocomposite. Compared to a pure titania reference, this material reveals a 7-fold-increased photodegradation rate of Rhodamine B as a model compound. This reveals the reactive hypersaline route to be a promising and facile synthesis route toward photoactive porous materials.

Polystyrene-block-poly(ethylene oxide) copolymers as templates for stacked, spherical large-mesopore silica coatings: dependence of silica pore size on the PS/PEO ratio

Summary Large-mesopore silica films with a narrow pore size distribution and high porosity have been obtained by a sol–gel reaction of a silicon oxide precursor (TEOS) and using polystyrene-block-poly(ethylene oxide) (PS-b-PEO) copolymers as templates in an acidic environment. PS-b-PEO copolymers with different molecular weight and composition have been studied in order to assess the effects of the block length on the pore size of the templated silica films. The changes in the morphology of the porous systems have been investigated by transmission electron microscopy and a systematic analysis has been carried out, evidencing the dependence between the hydrophilic/hydrophobic ratio of the two polymer blocks and the size of the final silica pores. The obtained results prove that by tuning the PS/PEO ratio, the pore size of the templated silica films can be easily and finely predicted.