1,721,059 research outputs found
Manufacturing at nanoscale: from molecular machines to transducers
No full textThis chapter starts with a brief discussion of the concepts of molecular device and machine and a description of the bottom-up (i.e., supramolecular) approach to their construction. The characteristics of molecular machines are then discussed with reference to those of macroscopic ones. In the second part, representative studies in solution are presented with the aim of illustrating the working principles
of synthetic linear and rotary molecular machines. The third section describes some remarkable achievements that demonstrate the potential utility of nanoscale machines to perform tasks. Finally, perspectives and limitations of this kind of systems are discussed in the Conclusion section
Electrospun nanofibrous multiscale scaffold for tendon and ligament tissue regeneration and replacement
No full textOrganogel Coupled with Microstructured Electrospun Polymeric Nonwovens for the Effective Cleaning of Sensitive Surfaces
Get PDFHydrogels and organogels are widely used as cleaning materials, especially when a controlled solvent release is necessary to prevent substrate damage. This situation is often encountered in the personal care and electronic components fields and represents a challenge in restoration, where the removal of a thin layer of aged varnish from a painting may compromise the integrity of the painting itself. There is an urgent need for new and effective cleaning materials capable of controlling and limiting the use of solvents, achieving at the same time high cleaning efficacy. In this paper, new sandwich-like composites that fully address these requirements are developed by using an organogel (poly(3-hydroxybutyrate) + γ-valerolactone) in the core and two external layers of electrospun nonwovens made of continuous submicrometric fibers produced by electrospinning (either poly(vinyl alcohol) or polyamide 6,6). The new composite materials exhibit an extremely efficient cleaning action that results in the complete elimination of the varnish layer with a minimal amount of solvent adsorbed by the painting layer after the treatment. This demonstrates that the combined materials exert a superficial action that is of utmost importance to safeguard the painting. Moreover, we found that the electrospun nonwoven layers act as mechanically reinforcement components, greatly improving the bending resistance of organogels and their handling. The characterization of these innovative cleaning materials allowed us to propose a mechanism to explain their action: electrospun fibers play the leading role by slowing down the diffusion of the solvent and by conferring to the entire composite a microstructured rough superficial morphology, enabling to achieve outstanding cleaning performance
Development of novel PLLA-scaffolds with enhanced biological performances obtained by loading of relevant beta-lactam based integrin ligands
No full textA safe, high-rate and high-energy polymer lithium-ion battery based on gelled membrane prepared by electrospinning
No full textDevice for interfacing filamentous or fibrous structures with a real or simulated biological tissue
No full textA device for interfacing at least one filamentous structure, with real or simulated biological tissue, comprising at least one body (10, 20) for anchoring the filamentous structure, said device being characterized in that said body (10, 20) comprises: at least one capstan (12, 22, 22', 22'), said capstan (12, 22, 22') being configured for wrapping the filamentous structure; at least one porous portion (13, 13', 24) having a trabecular structure (300); and system for regeneration, or repair, or replacement, or simulation of tendon and/or ligamentous tissue comprising said device and at least one filamentous structure comprising a plurality of nanofiber assemblies obtained by electrospinning, said plurality of assemblies being arranged to form a single bundle; said bundle being wrapped to the capstan (12)
Frontal polymerization of acrylamide/GelMA/gelatin hydrogels with controlled mechanical properties and inherent self-recovery
No full textLow mechanical resistance represents one of the significant problems of hydrogels, limiting their applicability in
many fields. One approach to overcome this issue is synthesizing interpenetrating polymeric networks. In this
work, the frontal polymerization technique was used to synthesize two series of novel hydrogels: (i) poly
(acrylamide) (PAAm)-based hydrogels copolymerized/crosslinked with methacrylate gelatin (GelMA) (AAmGelMA copolymer networks), and (ii) semi-IPN made of AAm-GelMA copolymer networks and a physically
crosslinked gelatin network. With the final objective of improving the rheological, mechanical, morphological,
thermal, and swelling properties of PAAm hydrogels, GelMA with two different degrees of methacrylation (30
and 75 mol%) was used. Interactions between GelMA chains, which give rise to physical network formation (i.e.,
GelMA-GelMA interactions), resulted in very efficient crosslinking for PAAm-based hydrogels, requiring a
significantly lower methacrylic group concentration (0.04 mol%) for hydrogel formation compared to N,N′-
methylene-bis-acrylamide (1 mol%), which is the agent typically used as a crosslinker for PAAm. Furthermore,
the degree of GelMA methacrylation markedly affected the properties of the hydrogels. For example, regarding
the swelling degree, hydrogels containing 22 wt% of GELMA30 had an SR% of 2870, while those containing the
same amount of GELMA75 swelled much less (870 %). The introduction of gelatin as a secondary network in
semi-IPNs influenced the rheological and mechanical properties, resulting in increased hydrogel modulus and
stiffness attributed to enhanced physical interactions within the network. Finally, dynamic rheological shear
strain and cyclic loading compression tests demonstrated exceptional recovery capabilities in all hydrogel formulations: samples subjected to alternating low (0.1 %) and high (300 % or 10 %) shear strain demonstrated a
complete and prompt recovery of G′ and G′′ values
Hierarchical scaffolds for the regeneration and/or simulation and/or replacementof bone tissue
No full textThepresent invention relates to a process for the preparation ofa porous hierarchical scaffold characterized b in- ternal pores organized according to a hierarchical structure, for
the regeneration, replacement and/or simulation ofabone tissue, in particular of the trabecular and/or cortical bone tissue. The present invention further relates to the porous hierarchical scaf- fold obtainable by such process and to the uses thereof. The in- vention furtherrelates to the useo fa sacrificial hierarchical scaf- fold for the preparationof such porous hierarchical scaffold
HIERARCHICAL MULTISCALE ELECTROSPUN SCAFFOLD FOR THE REGENERATION AND/OR REPLACEMENT OF THE TENDINOUS/LIGAMENTOUS TISSUE AND A METHOD FOR ITS PRODUCTION
No full textThe present invention relates to a support or a multiscale hierarchical scaffold for the tissue regeneration, in particular for the regeneration or replacement of the tendinous and/or ligamentous and/or muscular and/or nervous tissue. The present invention further relates to the processes for obtaining such support and the uses thereof
MORPHOLOGICALLY BIO-INSPIRED HIERARCHICAL NYLON 6,6 ELECTROSPUN STRUCTURES FOR SOFT-ROBOTICS APPLICATIONS
Get PDFThe last decades have seen an increasing attention on a new, ground-breaking field, soft-robotics [1]. Soft-robotics tries to overcome the limits of classical rigid robots, developing bioinspired structures with compliant and soft materials. Skeletal muscle is a biological, hierarchically arranged fibrous structure (Fig A), suitable to inspire innovative soft actuators. The possibility to mimic muscles and soft tissues has been demonstrated through the use of the electrospinning technique [2]. The aim of the present study was to develop and characterize innovative muscle-inspired, hierarchically arranged electrospun structures made of Nylon 6,6 for soft-robotics applications. In order to mimic skeletal muscle myofibrils [3], mats of aligned Nylon 6,6 nanofibers were electrospun on a rotating drum collector. To reproduce skeletal muscle fibers and fascicles morphology [3], the mats were cut in stripes and wrapped up on the drum, producing bundles of axially aligned nanofibers. The bundles were then pulled out from the drum, obtaining ring-shaped bundles. To mimic a whole skeletal muscle with its epimysium membrane [3], 2-levels hierarchical structure was developed (Fig B). Several bundles were aligned and packed together using a nanofibrous sheath produced through an innovative electrospinning setup [4]. Finally, in order to mimic also the skeletal muscle fascicles and perimysium [3], a 3-levels hierarchical structure was obtained by grouping together three 2-levels hierarchical structures, produced as previously described, with an additional electrospun sheath (Fig C). A morphological investigation of the different electrospun structures was carried out with scanning electron microscopy (SEM) and high-resolution x-ray tomography (XCT). The alignment of the nanofibers of the electrospun sheaths and the internal bundles, was quantified with a previously validated methodology [5]. The bundles and the 2-levels hierarchical structures were also mechanically characterized with a monotonic tensile test. The level of alignment of the nanofibers in the sheaths has proved to be tuneable by modifying the electrospinning parameters. The electrospun sheaths are also capable to tighten the structures wrapped inside, reducing their cross-sectional area and improving the apparent mechanical strength and stiffness. The high-resolution imaging confirmed that the mean diameters of the different hierarchical structures were comparable to the corresponding structures of biological skeletal muscle [3]. The directionality analysis on both bundles and sheaths nanofibers showed comparable levels of alignment with corresponding skeletal muscles fibrous tissues [3]. The mechanical test on the structures revealed a non-linear behaviour typical of soft tissue. The 2- levels hierarchical structures showed mechanical properties roughly proportional to the number of single bundles incorporated (with a possible underestimation of the ultimate strength, due to a stress concentration at the grips). In conclusion, this innovative electrospinning approach to produce hierarchically-arranged structures will be suitable to develop muscle-inspired assemblies. We will explore the possibility of incorporating adequate contracting ability so as to build soft actuators
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