scholarly journals Fabrication of Hierarchical Multilayer Poly(Glycerol Sebacate Urethane) Scaffolds Based on Ice-Templating

2021 ◽  
Vol 11 (11) ◽  
pp. 5004
Author(s):  
Andreas Samourides ◽  
Andreas Anayiotos ◽  
Konstantinos Kapnisis ◽  
Zacharoula Xenou ◽  
Vanessa Hearnden ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Freeze Drying ◽  
Soft Tissues ◽  
Polymer Concentration ◽  
Three Dimensional ◽  
Molar Ratio ◽  
Porous Layers ◽  
Custom Made ◽  
Dimensional Cell ◽  
Ice Templating

In this study, it was demonstrated that ice-templating via freeze drying with custom-made moulds, in combination with air brushing, allows for the fabrication of poly(glycerol sebacate urethane) (PGSU) scaffolds with hierarchical multilayer microstructures to replicate various native soft tissues. The PGSU scaffolds were either monolayered but exhibited an anisotropic microstructure, or bilayered and trilayered, with each layer showing different microstructures. By using freeze drying with custom-made moulds, the ice crystals of the solvent were grown unidirectionally, and after freeze-drying, the scaffolds had an anisotropic microstructure, mimicking tissues such as tendon and skeletal muscle. The anisotropic PGSU scaffolds were also examined for their tensile strength, and a range of mechanical properties were obtained by altering the reactants’ molar ratio and polymer concentration. This is of importance, since soft tissues exhibit different mechanical properties depending on their native location and functionality. By combining freeze drying with airbrushing, scaffolds were fabricated with a thin, non-porous layer on top of the porous layers to allow three-dimensional cell co-culture for tissues such as skin and oral mucosa. These results show that fabrication techniques can be combined to produce PGSU scaffolds with tailored hierarchical microstructures and mechanical properties for multiple tissue engineering applications.

MECHANICAL BEHAVIOR UNDER UNCONFINED COMPRESSION LOADINGS OF DENSE FIBRILLAR COLLAGEN MATRICES MIMETIC OF LIVING TISSUES

2010 ◽  
Vol 10 (01) ◽  
pp. 35-55 ◽  
Author(s):  
SALAH RAMTANI ◽  
YOSHIYUKI TAKAHASHI-IÑIGUEZ ◽  
CHRISTOPHE HELARY ◽  
DIDIER GEIGER ◽  
MARIE MADELEINE GIRAUD GUILLE
Keyword(s):  
Mechanical Properties ◽  
Soft Tissues ◽  
Three Dimensional ◽  
Fibrillar Collagen ◽  
Unconfined Compression ◽  
Collagen Scaffolds ◽  
Collagen Concentration ◽  
Collagen Matrices ◽  
Compression Load ◽  
Living Tissues

Bio-artificial tissues are being developed as replacements for damaged biologic tissues and their mechanical properties are critical for load-bearing applications. Reconstituted dense three-dimensional (3D) fibrillar collagen matrices are promising materials for tissue engineering, at the light of their interaction with fibroblasts.1,2 The mechanical properties of these fibrillar collagen matrices are now being characterized under unconfined compression loading for various strain rates and collagen concentrations. The data were compared to those obtained in the same conditions with a biological tissue, the rat dermis. The results show a very sensitive behavior to both the displacement rate, typical of biological soft tissues, and the collagen concentration varying between 5 and 40 mg/ml. The link between the mechanical properties and the microscopic structure of the collagen scaffolds show an increasing viscoelastic modulus with respect to the fibril density. It is found that the matrices at 5 mg/ml and the dorsal rat skin (DRS) exhibit similar stress–strain response when submitted to the same external unconfined compression load. Such results highlight the interest of these matrices as potential tissue substitutes.

Fabrication and Characterisation of Polymer and Composite Scaffolds Based on Polyhydroxybutyrate and Polyhydroxybutyrate-Co-Hydroxyvalerate

2007 ◽  
Vol 334-335 ◽  
pp. 1229-1232 ◽  
Author(s):  
Naznin Sultana ◽  
Min Wang
Keyword(s):  
Freeze Drying ◽  
Polymer Concentration ◽  
Three Dimensional ◽  
Polymer Scaffolds ◽  
Composite Scaffolds ◽  
Fabrication And Characterization ◽  
Fabrication Parameters ◽  
Highly Porous ◽  
Interconnected Pores

This paper reports the fabrication and characterization of three-dimensional, highly porous polyhydroxybutyrate (PHB), polyhydroxybutyrate-co-valerate (PHBV) and composite scaffolds made by the emulsion freezing / freezing-drying technique. Freeze-drying of the polymer/solvent/ water phase emulsions produced hard and tough scaffolds with interconnected pores. The effects of the fabrication parameters such as polymer concentration in emulsions and emulsion stabilizer were examined and optimized. The density of polymer scaffolds was found to increase with an increasing polymer concentration. Structural analyses of selected samples using scanning electron microscopy indicated that the scaffolds had pore sizes ranging from several microns to a few hundred microns. The porosity of scaffolds of up to 85% was achieved and it increased with a decreasing polymer concentration. It was found that mechanical properties of composite scaffolds increased with the increasing amount of hydroxyapatite (HA) incorporated in the scaffolds.

scholarly journals Strategies for Improving Antimicrobial Properties of Stainless Steel

Materials ◽  
2020 ◽  
Vol 13 (13) ◽  
pp. 2944 ◽  
Author(s):  
Matic Resnik ◽  
Metka Benčina ◽  
Eva Levičnik ◽  
Niharika Rawat ◽  
Aleš Iglič ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Stainless Steel ◽  
Surface Modification ◽  
Three Dimensional ◽  
Antibacterial Properties ◽  
Antimicrobial Properties ◽  
Biological Response ◽  
Surface Characteristics ◽  
Treatment Conditions ◽  
Custom Made

In this review, strategies for improving the antimicrobial properties of stainless steel (SS) are presented. The main focus given is to present current strategies for surface modification of SS, which alter surface characteristics in terms of surface chemistry, topography and wettability/surface charge, without influencing the bulk attributes of the material. As SS exhibits excellent mechanical properties and satisfactory biocompatibility, it is one of the most frequently used materials in medical applications. It is widely used as a material for fabricating orthopedic prosthesis, cardiovascular stents/valves and recently also for three dimensional (3D) printing of custom made implants. Despite its good mechanical properties, SS lacks desired biofunctionality, which makes it prone to bacterial adhesion and biofilm formation. Due to increased resistance of bacteria to antibiotics, it is imperative to achieve antibacterial properties of implants. Thus, many different approaches were proposed and are discussed herein. Emphasis is given on novel approaches based on treatment with highly reactive plasma, which may alter SS topography, chemistry and wettability under appropriate treatment conditions. This review aims to present and critically discuss different approaches and propose novel possibilities for surface modification of SS by using highly reactive gaseous plasma in order to obtain a desired biological response.

The Development and Performance Evaluation of Green Cross-Linked Movable Gel

2011 ◽  
Vol 418-420 ◽  
pp. 610-616 ◽  
Author(s):  
Cui Xia Li ◽  
Guang Hua Wen ◽  
Jian Jun Yang ◽  
Jian Guo Li ◽  
Yang Fan Zhou
Keyword(s):  
Laboratory Experiments ◽  
Polymer Concentration ◽  
Three Dimensional ◽  
Environmental Scanning Electron Microscopy ◽  
Salt Resistance ◽  
Molar Ratio ◽  
Environmental Scanning ◽  
Profile Modification ◽  
Aluminum Ions ◽  
And Performance

Through laboratory experiments, a green cross-linked movable gel has been developed, which has been used for reservoir profile modification. The main agent of gel is hydrophobic associating polymer, concentration is 3000mg/L; the cross-linking agent is Aluminum citrate from complex of Aluminum ion and citric acid root ion. The best molar ratio of aluminum ions and citrate ions is 1.5:1 in complex reaction, the amount is 140mg/L; the retarder is tartaric acid sodium, the amount is 150mg/L; The stabilizer is thiourea, the amount is 800mg/L; The strength of the green cross-linked movable gel is 3.12×104mPa.s, gelling time 36h, Stable time 160d; It is suitable for low-temperature reservoir profile modification, and salt resistance is good. Laboratory experiments show that the green cross-linked movable gel have strong plugging capacity and improving profile ability. The green cross-linked movable gel has strong three dimensional network structure, which be observed through the environmental scanning electron microscopy.

scholarly journals Combining Materials Obtained by 3D-Printing and Electrospinning from Commercial Polylactide Filament to Produce Biocompatible Composites

Polymers ◽  
2021 ◽  
Vol 13 (21) ◽  
pp. 3806
Author(s):  
Pablo Romero-Araya ◽  
Victor Pino ◽  
Ariel Nenen ◽  
Verena Cárdenas ◽  
Francisca Pavicic ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Tissue Engineering ◽  
3D Printing ◽  
Three Dimensional ◽  
Fibrillar Structure ◽  
3D Print ◽  
3T3 Fibroblasts ◽  
Custom Made ◽  
3D Printers ◽  
3D Printed

The design of scaffolds to reach similar three-dimensional structures mimicking the natural and fibrous environment of some cells is a challenge for tissue engineering, and 3D-printing and electrospinning highlights from other techniques in the production of scaffolds. The former is a well-known additive manufacturing technique devoted to the production of custom-made structures with mechanical properties similar to tissues and bones found in the human body, but lacks the resolution to produce small and interconnected structures. The latter is a well-studied technique to produce materials possessing a fibrillar structure, having the advantage of producing materials with tuned composition compared with a 3D-print. Taking the advantage that commercial 3D-printers work with polylactide (PLA) based filaments, a biocompatible and biodegradable polymer, in this work we produce PLA-based composites by blending materials obtained by 3D-printing and electrospinning. Porous PLA fibers have been obtained by the electrospinning of recovered PLA from 3D-printer filaments, tuning the mechanical properties by blending PLA with small amounts of polyethylene glycol and hydroxyapatite. A composite has been obtained by blending two layers of 3D-printed pieces with a central mat of PLA fibers. The composite presented a reduced storage modulus as compared with a single 3D-print piece and possessing similar mechanical properties to bone tissues. Furthermore, the biocompatibility of the composites is assessed by a simulated body fluid assay and by culturing composites with 3T3 fibroblasts. We observed that all these composites induce the growing and attaching of fibroblast over the surface of a 3D-printed layer and in the fibrous layer, showing the potential of commercial 3D-printers and filaments to produce scaffolds to be used in bone tissue engineering.

Revealing gross three-dimensional structure in the SEM

1987 ◽  
Vol 45 ◽  
pp. 656-657
Author(s):  
Sterling P. Newberry
Keyword(s):  
Freeze Drying ◽  
Three Dimensional ◽  
Dimensional Structure ◽  
Small Object ◽  
Final Solution ◽  
Dimensional Representation ◽  
X Ray ◽  
Three Dimensional Representation ◽  
Freeze Dried ◽  
Critical Point Drying

The beautiful three dimensional representation of small object surfaces by the SEM leads one to search for ways to open up the sample and look inside. Could this be the answer to a better microscopy for gross biological 3-D structure? We know from X-Ray microscope images that Freeze Drying and Critical Point Drying give promise of adequately preserving gross structure. Can we slice such preparations open for SEM inspection? In general these preparations crush more readily than they slice. Russell and Dagihlian got around the problem by “deembedding” a section before imaging. This some what defeats the advantages of direct dry preparation, thus we are reluctant to accept it as the final solution to our problem. Alternatively, consider fig 1 wherein a freeze dried onion root has a window cut in its surface by a micromanipulator during observation in the SEM.

Biotemplated facile synthesis of three‐dimensional micro/nanoporous tin oxide: improving the flammable and mechanical properties of flexible PVC

2019 ◽  
Vol 14 (8) ◽  
pp. 828-830 ◽  
Author(s):  
Weihua Meng ◽  
Weihong Wu ◽  
Weiwei Zhang ◽  
Luyao Cheng ◽  
Yunhong Jiao ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Tin Oxide ◽  
Three Dimensional ◽  
Facile Synthesis

Adult Acquired Flatfoot

2020 ◽  
Vol 62 (1) ◽  
pp. 55-59
Author(s):  
Krzysztof Mataczyński ◽  
Mateusz Pelc ◽  
Halina Romualda Zięba ◽  
Zuzana Hudakova
Keyword(s):  
Soft Tissues ◽  
Three Dimensional ◽  
Clinical Diagnostics ◽  
Clinical Image ◽  
Tibialis Posterior ◽  
Dynamic Force ◽  
Posterior Tibial ◽  
Flat Feet ◽  
Foot Arch ◽  
Motion Range

Acquired adult flatfoot is a three-dimensional deformation, which consists of hindfoot valgus, collapse of the longitudinal arch of the foot and adduction of the forefoot. The aim of the work is to present problems related to etiology, biomechanics, clinical diagnostics and treatment principles of acquired flatfoot. The most common cause in adults is the dysfunction of the tibialis posterior muscle, leading to the lack of blocking of the transverse tarsal joint during heel elevation. Loading the unblocked joints consequently leads to ligament failure. The clinical image is dominated by pain in the foot and tibiotarsal joint. The physical examination of the flat feet consists of: inspection, palpation, motion range assessment and dynamic force assessment. The comparable attention should be paid to the height of the foot arch, the occurrence of “too many toes” sign, evaluate the heel- rise test and correction of the flatfoot, exclude Achilles tendon contracture. The diagnosis also uses imaging tests. In elastic deformations with symptoms of posterior tibial tendonitis, non-steroidal anti-inflammatory drugs, short-term immobilization, orthotics stabilizing the medial arch of the foot are used. In rehabilitation, active exercises of the shin muscles and the feet, especially the eccentric exercises of the posterior tibial muscle, are intentional. The physiotherapy and balneotherapy treatments, in particular hydrotherapy, electrotherapy and laser therapy, are used as a support. In advanced lesions, surgical treatment may be necessary, including plastic surgery of soft tissues, tendons, as well as osteotomy procedures.

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