Antibacterial composite membranes of PCL/gelatin loaded with ZnO nanoparticles for guided tissue regeneration.

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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Nanoparticles (NPs) of CuBi2O4 with an average size around 25 nm were obtained by a novel and eco-friendly synthesis method. X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HR-TEM) reveal that CuBi2O4 NPs possess a tetragonal crystal structure. These NPs were characterised by Raman scattering, ultraviolet-visible (UV-Vis) absorption, photoluminescence (PL), and electron paramagnetic resonance (EPR) spectroscopies. Furthermore, an in vitro study of the antibacterial effect of CuBi2O4 NPs against two bacterial strains, Pseudomonas aeruginosa (ATCC 43636) and Staphylococcus aureus (ATCC 25923), was carried out. The results obtained from the counting of colony-forming units (CFUs) and by the XTT-PMS cell viability assay showed an inhibition of the bacterial growth by 88%–87% for P. aeruginosa and 100% for S. aureus, at 50 mg ml−1 of NPs concentration. The results of this work suggest that these nanoparticles have the potential to be used as antibacterial agents by embedding them into different surfaces or being dispersed in a coating, to prevent the bacterial colonisation.

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 TiO 2 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 TiO 2 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 TiO 2 lattices alone did not modify motor symptoms in lesioned rats. DA-unloaded or -loaded TiO 2 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 TiO 2 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.

Periodontitis is a chronic, multifactorial, inflammatory disease characterized by the progressive destruction of the periodontal tissues. Guided tissue regeneration (GTR), involving the use of barrier membranes, is one of the most successful clinical procedures for periodontal therapy. Nevertheless, rapid degradation of the membranes and membrane-related infections are considered two of the major reasons for GTR clinical failure. Recently, integration of non-antibiotic, antimicrobial materials to the membranes has emerged as a novel strategy to face the bacterial infection challenge, without increasing bacterial resistance. In this sense, bismuth subsalicylate (BSS) is a non-antibiotic, metal-based antimicrobial agent effective against different bacterial strains, that has been long safely used in medical treatments. Thus, the aim of the present work was to fabricate fibrillar, non-rapidly bioresorbable, antibacterial GTR membranes composed of polycaprolactone (PCL), gelatin (Gel), and BSS as the antibacterial agent. PCL-G-BSS membranes with three different BSS concentrations (2 wt./v%, 4 wt./v%, and 6 wt./v%) were developed by electrospinning and their morphology, composition, water wettability, mechanical properties, Bi release and degradation rate were characterized. The Cytotoxicity of the membranes was studied in vitro using human osteoblasts (hFOB) and gingival fibroblasts (HGF-1), and their antibacterial activity was tested against Aggregatibacter actinomycetemcomitans, Escherichia coli, Porphyromonas gingivalis and Staphylococcus aureus. The membranes obtained exhibited adequate mechanical properties for clinical application, and appropriate degradation rates for allowing periodontal defects regeneration. The hFOB and HGF-1 cells displayed adequate viability when in contact with the lixiviated products from the membranes, and, in general, displayed antibacterial activity against the four bacteria strains tested. Thus, the PCL-G-BSS membranes showed to be appropriate as potential barrier membranes for periodontal GTR treatments.

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