1,721,068 research outputs found
Genipin-based crosslinking of jellyfish collagen 3d hydrogels
No full textCollagen-based hydrogels are an attractive option in the field of cartilage regeneration with features of high biocompatibility and low immunogenic response. Crosslinking treatments are often employed to create stable 3D gels that can support and facilitate cell embodiment. In this study, we explored the properties of JellaGelTM, a novel jellyfish material extracted from Rhizostoma pulmo. In particular, we analyzed the influence of genipin, a natural crosslinker, on the formation of 3D stable JellaGelTM hydrogels embedding human chondrocytes. Three concentrations of genipin were used for this purpose (1 mM, 2.5 mM, and 5 mM). Morphological, thermal, and mechanical properties were investigated for the crosslinked materials. The metabolic activity of embedded chondrocytes was also evaluated at different time points (3, 7, and 14 days). Non-crosslinked hydrogels resulted in an unstable matrix, while genipin-crosslinked hydrogels resulted in a stable matrix, without significant changes in their properties; their collagen network revealed characteristic dimensions in the order of 20 μm, while their denaturation temperature was 57◦C. After 7 and 14 days of culture, chondrocytes showed a significantly higher metabolic activity within the hydrogels crosslinked with 1 mM genipin, compared to those crosslinked with 5 mM genipin
A novel concept of steerable catheters actuated by muscle cells: the BioMeld project
No full textLocalized (targeted) therapies allow increasing the efficacy of treatments for several diseases, including cancer. Within this view, the BioMeld project aims at proposing a pipeline to guide the fabrication of an innovative intravascular steerable microcatheter, actuated on its tip by muscle cell contraction. A simulation framework streamlines the process of design quoting, manufacturing, verification, and reporting, thus significantly reducing error-prone manual steps and making the process more efficient. This new generation of steerable microcatheter, fostered by the unconventional kind of actuation provided by muscle cells, will be investigated throughout this project to target localized treatments of deeper and tortuous regions within the cardiovascular systems. In this work we report the overall project vision and we describe some preliminary results on the microcatheter design
Highly controlled ultrasound-mediated drug delivery experiments: an in vitro set-up
No full textThis work reports the design, development and characterization of a low-intensity pulsed ultrasound (LIPUS) stimulation system to be used for highly controlled ultrasound-triggered drug delivery in vitro experiments. The use of a versatile signal generator and different types of transducers allows the fine tuning of the stimulation parameters over a broad range. Such transducers were carefully characterized in terms of pressure field shape and intensity, guaranteeing a precise estimation and control of the ultrasound dose delivered to the target. Such a system will be used for controlled drug release tests from ultrasound-responsive systems, such as nano and micro carriers, scaffolds and patches, in the context of the REBORN project
Ex-vivo quantitative ultrasound assessment of cartilage degeneration
No full textOsteoarthritis is a common disease that implies joint degeneration and that strongly affects the quality of life. Conventional radiography remains currently the most used diagnostic method, even if it allows only an indirect assessment of the articular cartilage and employ the use of ionizing radiations. A non-invasive, continuous and reliable diagnosis is crucial to detect impairments and to improve the treatment outcomes.Quantitative ultrasound techniques have proved to be very useful in providing an objective diagnosis of several soft tissues. In this study, we propose quantitative ultrasound parameters, based on the analysis of radiofrequency data derived from both healthy and osteoarthritis-mimicking (through chemical degradation) ex-vivo cartilage samples. Using a transmission frequency typically employed in the clinical practice (7.5-15 MHz) with an external ultrasound probe, we found results in terms of reflection at the cartilage surface and sample thickness comparable to those reported in the literature by exploiting arthroscopic transducers at high frequency (from 20 to 55 MHz). Moreover, for the first time, we introduce an objective metric based on the phase entropy calculation, able to discriminate the healthy cartilage from the degenerated one.Clinical Relevance - This preliminary study proposes a novel and quantitative method to discriminate healthy from degenerated cartilage. The obtained results pave the way to the use of quantitative ultrasound in the diagnosis and monitoring of knee osteoarthritis
Novel Ultrathin Films Based on a Blend of PEG- b-PCL and PLLA and Doped with ZnO Nanoparticles
No full textIn this paper, a novel nanofilm type is proposed based on a blend of poly(ethylene glycol)-block-poly(ε-caprolactone) methyl ether (PEG-b-PCL) and poly(l-lactic acid), doped with zinc oxide nanoparticles (ZnO NPs) at different concentrations (0.1, 1, and 10 mg/mL). All nanofilm types were featured by a thickness value of ∼500 nm. Increasing ZnO NP concentrations implied larger roughness values (∼22 nm for the bare nanofilm and ∼67 nm for the films with 10 mg/mL of NPs), larger piezoelectricity (average d33 coefficient for the film up to ∼1.98 pm/V), and elastic modulus: the nanofilms doped with 1 and 10 mg/mL of NPs were much stiffer than the nondoped controls and nanofilms doped with 0.1 mg/mL of NPs. The ZnO NP content was also directly proportional to the material melting point and crystallinity and inversely proportional to the material degradation rate, thus highlighting the stabilization role of ZnO particles. In vitro tests were carried out with cells of the musculoskeletal apparatus (fibroblasts, osteoblasts, chondrocytes, and myoblasts). All cell types showed good adhesion and viability on all substrate formulations. Interestingly, a higher content of ZnO NPs in the matrix demonstrated higher bioactivity, boosting the metabolic activity of fibroblasts, myoblasts, and chondrocytes and enhancing the osteogenic and myogenic differentiation. These findings demonstrated the potential of these nanocomposite matrices for regenerative medicine applications, such as tissue engineering
A Layer Jamming Actuator for Tunable Stiffness and Shape-Changing Devices
No full textChanging the shape and the stiffness of a device in a dynamic and controlled way enables important advancements in the field of robotics and wearable robotics. Variable stiffness materials and technologies can be used to address this challenge. In particular, layer jamming actuation is a very promising technology, featured by high efficiency and low cost. In this article, a stiffness- and shape-changing device based on a novel mechanism including a multiple-chamber structure is proposed. It allows to effectively modulate the shape and stiffness of a device, by activating two jamming chambers while pressurizing/depressurizing one or more interposed inflatable chambers. Prototypes with a size of 45 x 270 mm(2) and an average thickness ranging from 4.4 to 13 mm were developed and their ability to undergo a stiffness change over two orders of magnitude was demonstrated. The prototypes were also able to change their shape according to the position and inflation level of the interposed inflatable chambers, thus resulting in an overall deflection >10 mm. The possibility to wear the system as an orthotic brace was also demonstrated: this technology increased the patient comfort in static positions, yet keeping a supportive function when needed (e.g., in dynamic conditions). The device working principle highlighted in this article could also be exploited in other domains, for example, to build walking soft robots, prostheses, or grippers, as demonstrated through additional tests
Gellan gum-based hydrogels as injectable materials for cartilage tissue engineering
No full textRecently, new tissue engineering approaches are being developed as an alternative to traditional treatments for cartilage repair. Materials in the form of hydrogels are particularly attractive as owing to their biocompatibility, degradability, and ability to homogeneously mix with stem cells and bioactive molecules. Hydrogels can be injectable, thus to easily fill defects with different shapes, thus repairing the articular cartilage in a minimally invasive way. This manuscript reports the analysis of gellan gum-based hydrogels as injectable materials for the in situ delivery of chondrocytes for the treatment of cartilage defects. Gellan gum and methacrylated gellan gum were prepared and analyzed through rheometry, to assess their suitability for being injected with chondrocytes. Then, one selected formulation was further characterized in terms of mechanical properties, analyzing the influence of light exposure. Finally, preliminary biological tests with chondrocytes were performed to analyze the interaction with the material
A novel quantitative and reference-free ultrasound analysis to discriminate different concentrations of bone mineral content
Full text linkBone fracture is a continuous process, during which bone mineral matrix evolves leading to an increase in hydroxyapatite and calcium carbonate content. Currently, no gold standard methods are available for a quantitative assessment of bone fracture healing. Moreover, the available tools do not provide information on bone composition. Whereby, there is a need for objective and non-invasive methods to monitor the evolution of bone mineral content. In general, ultrasound can guarantee a quantitative characterization of tissues. However, previous studies required measurements on reference samples. In this paper we propose a novel and reference-free parameter, based on the entropy of the phase signal calculated from the backscattered data in combination with amplitude information, to also consider absorption and scattering phenomena. The proposed metric was effective in discriminating different hydroxyapatite (from 10 to 50% w/v) and calcium carbonate (from 2 to 6% w/v) concentrations in bone-mimicking phantoms without the need for reference measurements, paving the way to their translational use for the diagnosis of tissue healing. To the best of our knowledge this is the first time that the phase entropy of the backscattered ultrasound signals is exploited for monitoring changes in the mineral content of bone-like materials
Metal/polymer composite Nuss bar for minimally invasive bar removal after Pectus Excavatum treatment: FEM simulations
No full textThis study aims at assessing the mechanical behavior of a composite metal/polymer bar to be implanted in the retrosternal position, in order to correct chest wall deformities, such as Pectus Excavatum. A 300-mm-long, 12.7-mm-wide, and 3.5-mm-thick Nuss bar was considered, made of different metals and biodegradable polymers, fixed at its extremities, and with a constant force of 250 N applied on its center. Two different geometries for the metal elements to be embedded in the polymeric matrix were tested: in the former, thin metal sheets and in the latter, cylindrical metal reinforcing rods were considered. Finite element method simulation results are reported, in terms of maximum stress and strain of the bar. Furthermore, the maximum stress values obtained by varying metal sheet thickness or rod diameter (and therefore the volumetric percentage of metal within the matrix) for different material combinations are also shown; optimal configuration for the Pectus Excavatum treatment was finally identified for a composite Nuss bar
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