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Periodontitis is a highly prevalent infectious disease that causes the progressive destruction of the periodontal supporting tissues. If left untreated, it can lead to tooth loss impairing oral function, aesthetics, and the patient's overall quality of life. Guided and Bone Tissue Regeneration (GTR/BTR) are surgical therapies based on the placement of a membrane that prevents epithelial growth into the defect, allowing the periodontal/bone cells (including stem cells) to regenerate or restore the affected tissues. The success of these therapies is commonly affected by the local bacterial colonization of the membrane area and its fast biodegradation, causing postoperative infections and a premature rupture of the membrane limiting the regeneration process. This study presents the antibacterial and osteogenic differentiation properties of polycaprolactone-gelatin (PCL-G) electrospun membranes modified with ZnO nanoparticles (ZnO-NPs). The membranes´ chemical composition, surface roughness, biodegradation, water wettability, and mechanical properties under simulated physiological conditions, were analyzed by the close relationship with their biological properties. The PCL-G membranes modified with 1, 3, and 6% w/w of ZnO-NPs showed a significant reduction in the planktonic and biofilm formation of four clinically relevant bacteria;A. actinomycetemcomitansserotype b, P. gingivalis,E. coli, andS. epidermidis. Additionally, the membranes presented appropriate mechanical properties and biodegradation rates to be potentially used in clinical treatments. Notably, the membranes modified with the lowest concentration of ZnO-NPs (1% w/w) stimulated the production of osteoblast markers and calcium deposits in human bone marrow-derived mesenchymal stem cells (BM-MSC) and were biocompatible to human osteoblasts cells (hFOB). These results suggest that the PCL-G membranes with 1% w/w of ZnO-NPs are high-potential candidates for GTR/BTR treatments, as they were the most effective in terms of better antibacterial effectiveness at a lower NPs-concentration while creating a favorable cellular microenvironment for bone growth.

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The bacterial colonization of absorbable membranes used for guided tissue regeneration (GTR), as well as their rapid degradation that can cause their rupture, are considered the major reasons for clinical failure. To address this, composite membranes of polycaprolactone (PCL) and gelatin (Gel) loaded with zinc oxide nanoparticles (ZnO-NPs; 1, 3 and 6 wt% relative to PCL content) were fabricated by electrospinning. To fabricate homogeneous fibrillar membranes, acetic acid was used as a sole common solvent to enhance the miscibility of PCL and Gel in the electrospinning solutions. The effects of ZnO-NPs in the physico-chemical, mechanical and in vitro biological properties of composite membranes were studied. The composite membranes showed adequate mechanical properties to offer a satisfactory clinical manipulation and an excellent conformability to the defect site while their degradation rate seemed to be appropriate to allow successful regeneration of periodontal defects. The presence of ZnO-NPs in the composite membranes significantly decreased the planktonic and the biofilm growth of the Staphylococcus aureus over time. Finally, the viability of human osteoblasts and human gingival fibroblasts exposed to the composite membranes with 1 and 3 wt% of ZnO-NPs indicated that those membranes are not expected to negatively influence the ability of periodontal cells to repopulate the defect site during GTR treatments. The results here obtained suggest that composite membranes of PCL and Gel loaded with ZnO-NPs have the potential to be used as structurally stable GTR membranes with local antibacterial properties intended for enhancing clinical treatments.

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Blends of natural and synthetic polymers have recently attracted great attention as scaffolds for tissue engineering applications due to their favorable biological and mechanical properties. Nevertheless, phase-separation of blend components is an important challenge facing the development of electrospun homogeneous fibrillar natural-synthetic polymers scaffolds; phase-separation can produce significant detrimental effects for scaffolds fabricated by electrospinning. In the present study, blends of gelatin (Gel; natural polymer) and polycaprolactone (PCL; synthetic polymer), containing 30 and 45 wt% Gel, were prepared using acetic acid as a 'green' sole solvent to straightforwardly produce appropriate single-step Gel-PCL solutions for electrospinning. Miscibility of Gel and PCL in the scaffolds was assessed and the morphology, chemical composition and structural and solid-state properties of the scaffolds were thoroughly investigated. Results showed that the two polymers proved miscible under the single-step solution process used and that the electrospun scaffolds presented suitable properties for potential skin tissue engineering applications. Viability, metabolic activity and protein expression of human fibroblasts cultured on the Gel-PCL scaffolds were evaluated using LIVE/DEAD (calcein/ethidium homodimer), MTT-Formazan and immunocytochemistry assays, respectively. In vitro results showed that the electrospun Gel-PCL scaffolds enhanced cell viability and proliferation in comparison to PCL scaffolds. Furthermore, scaffolds allowed fibroblasts expression of extracellular matrix proteins, tropoelastin and collagen Type I, in a similar way to positive controls. Results indicated the feasibility of the single-step solution process used herein to obtain homogeneous electrospun Gel-PCL scaffolds with Gel content ≥30 wt% and potential properties to be used as scaffolds for skin tissue engineering applications for wound healing.

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The motor dysfunction featured by patients aggrieved by Parkinson's disease (PD) results from the reduction of dopamine (DA) availability in the caudate nucleus (CN). Restituting CN DA levels is therefore essential to ameliorate PD motor deficits. In this regard, nanotechnology may offer solutions to restore CN DA availability. DA, however, can be rapidly oxidized into toxic compounds if made available in situ, unprotected. Then, we tested whether a semicrystalline TiO2 lattice, implanted into the CN of 6-hydroxydopamine (6-OHDA)-lesioned, hemiparkinsonian rats, was able to release DA during a time window sufficient to attenuate motor symptoms while protecting it from the ongoing oxidation. Accordingly, implanted semicrystalline TiO2 lattices released incremental amounts of DA into the CN of lesioned rats. Motor symptoms were already attenuated by the 1st month and significantly reduced 2 months after implantation. These effects were specific since TiO2 lattices alone did not modify motor symptoms in lesioned rats. DA-unloaded or -loaded TiO2 lattices did not produce obvious symptoms of systemic or neurological toxicity nor significantly increased CN lipid peroxidation in implanted, lesioned rats at the time of sacrifice. Our results thus support that loaded TiO2 lattices are capable of releasing DA while protecting it from the ongoing oxidation when implanted into the brain. Their implantation does not cause noticeable systemic or local toxicity. On the contrary, they attenuated motor symptoms in hemiparkinsonian rats.

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ZnO and Zn acetate nanoparticles were embedded in polycaprolactone coaxial-fibers and uniaxial-fibers matrices to develop potential antibacterial nanocomposite wound dressings (mats). Morphology, composition, wettability, crystallinity and fiber structure of mats were characterized. Antibacterial properties of mats were tested against E. coli and S. aureus by turbidity and MTT assays. The effect of UVA illumination (prior to bacteria inoculation) on mats' antibacterial activity was also studied. Results showed that a coaxial-fibers design maintained nanoparticles distributed in the outer-shell of fibers and, in general, enhanced the antibacterial effect of the mats, in comparison to conventional uniaxial-fibers mats. Results indicated that mats simultaneously inhibited planktonic and biofilm bacterial growth by, probably, two main antibacterial mechanisms; 1) release of Zn2+ ions (mainly from Zn acetate nanoparticles) and 2) photocatalytic oxidative processes exerted by ZnO nanoparticles. Antibacterial properties of mats were significantly improved by coaxial-fibers design and exposure to UVA-light prior to bacteria inoculation.

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We report on the photoconductive response of nanostructured sol-gel films in function of the silver nitrate concentration (ions and colloids). Silver colloids were obtained by spontaneous reduction process of Ag+ ions to Ag(0). 2-d hexagonal nanosructured sol-gel thin films were prepared by dip-coating method using the non-ionic diblock copolymer Brij58 to produce channels into the film, which house the silver nanoparticles. An optical absorption band located at 430 nm was detected by optical absorption; it corresponds to the surface plasmon. A fit to this band with modified Gans theory is presented. Photoconductivity studies were performed on films with silver ions and films with silver colloids to characterize their mechanisms of charge transport in the darkness and under illumination at 420 and 633 nm wavelengths. The films with silver colloids exhibit a photovoltaic effect stronger than the films with silver ions. While a photoconductive behaviour is observed in the films with silver ions.

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Pump-probe photoinduced birefringence measurements were carried out in amorphous and in nanostructured sol-gel films with Disperse Red 1 (DR1) azochromophores embedded in a SiO2 matrix. X-ray diffraction (XRD) patterns determine the long-range nanostructure order of the films, exhibiting a lamellar nanostructure, with two different d-spacings, due to the presence during the sol-gel process of the Sodium Dodecyl Sulfate (SDS) or of the Cetyltrimethylammonium Bromide (CTAB) ionic surfactants. The photoinduced birefringence measurements were performed on fresh and on heat treated films as a function of the pumping time. The measurements give us information about the effect of the nanostructures on the azochromophores orientation dynamics. As a result, for the same azochromophores concentration, annealed nanostructured films exhibited the largest azochromophore mobilities but by the other side, amorphous films had the largest signal intensities. Besides, we established a phenomenological model for the analysis of the azochromophores orientation in the films as a function of the pumping time.