Effect of in vitro enzymatic degradation on 3D printed poly(ε-caprolactone) scaffolds: morphological, chemical and mechanical properties

In this study, we investigated the dual-pore kagome-structure design of a 3D-printed scaffold with enhanced in vitro cell response and compared the mechanical properties with 3D-printed scaffolds with conventional or offset patterns. The compressive modulus of the 3D-printed scaffold with the proposed design was found to resemble that of the 3D-printed scaffold with a conventional pattern at similar pore sizes despite higher porosity. Furthermore, the compressive modulus of the proposed scaffold surpassed that of the 3D-printed scaffold with conventional and offset patterns at similar porosities owing to the structural characteristics of the kagome structure. Regarding the in vitro cell response, cell adhesion, cell growth, and ALP concentration of the proposed scaffold for 14 days was superior to those of the control group scaffolds. Consequently, we found that the mechanical properties and in vitro cell response of the 3D-printed scaffold could be improved by kagome and dual-pore structures through DfAM. Moreover, we revealed that the dual-pore structure is effective for the in vitro cell response compared to the structures possessing conventional and offset patterns.

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Nanostructural and mechanical changes in the sclera following proteoglycan depletion

Modeling and Artificial Intelligence in Ophthalmology ◽

10.35119/maio.v2i2.65 ◽

2018 ◽

Vol 2 (2) ◽

pp. 14-17

Author(s):

Zhuola Zhuola ◽

Steve Barrett ◽

Yalda Ashraf Kharaz ◽

Riaz Akhtar

Keyword(s):

Mechanical Properties ◽

Collagen Fibril ◽

Enzymatic Degradation ◽

Ocular Tissues ◽

Force Microscopy ◽

Nanomechanical Properties ◽

Atomic Force ◽

Fibril Morphology

The mechanical properties of ocular tissues, such as the sclera, have a major impact on healthy eye function, and are governed by the properties and composition of the microstructural components. For example, biomechanical degradation associated with myopia occurs alongside a reduction of proteoglycans (PGs). In this study, the role of PG degradation in the nanomechanical properties of the porcine sclera is explored. In-vitro enzymatic degradation of PGs was conducted with α-amylase and chondroitinase ABC enzymes. Collagen fibril morphology and nanomechanical stiffness were measured with atomic force microscopy (AFM). The elastic modulus of the tissue was reduced in all enzyme-treated samples relative to controls. In addition, collagen fibril organization was disrupted by PG depletion. Our data demonstrate that PGs play an important role in determining not only the mechanical properties at these length scales, but also collagen fibril arrangement.

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Radiopaque Chitosan Ducts Fabricated by Extrusion-Based 3D Printing to Promote Healing After Pancreaticoenterostomy

Frontiers in Bioengineering and Biotechnology ◽

10.3389/fbioe.2021.686207 ◽

2021 ◽

Vol 9 ◽

Author(s):

Maoen Pan ◽

Chaoqian Zhao ◽

Zeya Xu ◽

Yuanyuan Yang ◽

Tianhong Teng ◽

...

Keyword(s):

Mechanical Properties ◽

Molecular Weight ◽

Pancreatic Duct ◽

Silicone Rubber ◽

The Body ◽

Molecular Weights ◽

Pancreatic Duct Stent ◽

3D Printed

Long-term placement of non-degradable silicone rubber pancreatic duct stents in the body is likely to cause inflammation and injury. Therefore, it is necessary to develop degradable and biocompatible stents to replace silicone rubber tubes as pancreatic duct stents. The purpose of our research was to verify the feasibility and biological safety of extrusion-based 3D printed radiopaque chitosan (CS) ducts for pancreaticojejunostomy. Chitosan-barium sulfate (CS-Ba) ducts with different molecular weights (low-, medium-, and high-molecular weight CS-Ba: LCS-Ba, MCS-Ba, and HCS-Ba, respectively) were soaked in vitro in simulated pancreatic juice (SPJ) (pH 8.0) with or without pancreatin for 16 weeks. Changes in their weight, water absorption rate and mechanical properties were tested regularly. The biocompatibility, degradation and radiopaque performance were verified by in vivo and in vitro experiments. The results showed that CS-Ba ducts prepared by this method had regular compact structures and good molding effects. In addition, the lower the molecular weight of the CS-Ba ducts was, the faster the degradation rate was. Extrusion-based 3D-printed CS-Ba ducts have mechanical properties that match those of soft tissue, good biocompatibility and radioopacity. In vitro studies have also shown that CS-Ba ducts can promote the growth of fibroblasts. These stents have great potential for use in pancreatic duct stent applications in the future.

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Fabrication and In Vitro Evaluation of 3D Printed Porous Polyetherimide Scaffolds for Bone Tissue Engineering

BioMed Research International ◽

10.1155/2019/2076138 ◽

2019 ◽

Vol 2019 ◽

pp. 1-8 ◽

Cited By ~ 1

Author(s):

Xiongfeng Tang ◽

Yanguo Qin ◽

Xinyu Xu ◽

Deming Guo ◽

Wenli Ye ◽

...

Keyword(s):

Mechanical Properties ◽

Tissue Engineering ◽

Cell Proliferation ◽

Cell Adhesion ◽

3D Printing ◽

Bone Tissue Engineering ◽

Bone Tissue ◽

Porous Scaffold ◽

3D Printed

For bone tissue engineering, the porous scaffold should provide a biocompatible environment for cell adhesion, proliferation, and differentiation and match the mechanical properties of native bone tissue. In this work, we fabricated porous polyetherimide (PEI) scaffolds using a three-dimensional (3D) printing system, and the pore size was set as 800 μm. The morphology of 3D PEI scaffolds was characterized by the scanning electron microscope. To investigate the mechanical properties of the 3D PEI scaffold, the compressive mechanical test was performed via an electronic universal testing system. For the in vitro cell experiment, bone marrow stromal cells (BMSCs) were cultured on the surface of the 3D PEI scaffold and PEI slice, and cytotoxicity, cell adhesion, and cell proliferation were detected to verify their biocompatibility. Besides, the alkaline phosphatase staining and Alizarin Red staining were performed on the BMSCs of different samples to evaluate the osteogenic differentiation. Through these studies, we found that the 3D PEI scaffold showed an interconnected porous structure, which was consistent with the design. The elastic modulus of the 3D PEI scaffold (941.33 ± 65.26 MPa) falls in the range of modulus for the native cancellous bone. Moreover, the cell proliferation and morphology on the 3D PEI scaffold were better than those on the PEI slice, which revealed that the porous scaffold has good biocompatibility and that no toxic substances were produced during the progress of high-temperature 3D printing. The osteogenic differentiation level of the 3D PEI scaffold and PEI slice was equal and ordinary. All of these results suggest the 3D printed PEI scaffold would be a potential strategy for bone tissue engineering.

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Development of Custom Wall-Less Cardiovascular Flow Phantoms with Tissue-Mimicking Gel

Cardiovascular Engineering and Technology ◽

10.1007/s13239-021-00546-7 ◽

2021 ◽

Author(s):

Megan E. Laughlin ◽

Sam E. Stephens ◽

Jamie A. Hestekin ◽

Morten O. Jensen

Keyword(s):

Mechanical Properties ◽

Continuous Flow ◽

Cardiac Tissue ◽

Flow Imaging ◽

Straight Channel ◽

Young’S Moduli ◽

Flow Phantom ◽

Cardiovascular Flow ◽

3D Printed

Abstract Purpose Flow phantoms are used in experimental settings to aid in the simulation of blood flow. Custom geometries are available, but current phantom materials present issues with degradability and/or mimicking the mechanical properties of human tissue. In this study, a method of fabricating custom wall-less flow phantoms from a tissue-mimicking gel using 3D printed inserts is developed. Methods A 3D blood vessel geometry example of a bifurcated artery model was 3D printed in polyvinyl alcohol, embedded in tissue-mimicking gel, and subsequently dissolved to create a phantom. Uniaxial compression testing was performed to determine the Young’s moduli of the five gel types. Angle-independent, ultrasound-based imaging modalities, Vector Flow Imaging (VFI) and Blood Speckle Imaging (BSI), were utilized for flow visualization of a straight channel phantom. Results A wall-less phantom of the bifurcated artery was fabricated with minimal bubbles and continuous flow demonstrated. Additionally, flow was visualized through a straight channel phantom by VFI and BSI. The available gel types are suitable for mimicking a variety of tissue types, including cardiac tissue and blood vessels. Conclusion Custom, tissue-mimicking flow phantoms can be fabricated using the developed methodology and have potential for use in a variety of applications, including ultrasound-based imaging methods. This is the first reported use of BSI with an in vitro flow phantom.

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Biomimetic Mineralization on 3D Printed PLA Scaffolds: On the Response of Human Primary Osteoblasts Spheroids and In Vivo Implantation

Polymers ◽

10.3390/polym13010074 ◽

2020 ◽

Vol 13 (1) ◽

pp. 74

Author(s):

Marianna O. C. Maia-Pinto ◽

Ana Carolina B. Brochado ◽

Bruna Nunes Teixeira ◽

Suelen C. Sartoretto ◽

Marcelo J. Uzeda ◽

...

Keyword(s):

Mechanical Properties ◽

Growth Factors ◽

Growth Factor ◽

Biological Response ◽

Primary Osteoblast ◽

Rat Calvaria ◽

3D Printed ◽

Human Primary Osteoblast

This study aimed to assess the response of 3D printed polylactic acid (PLA) scaffolds biomimetically coated with apatite on human primary osteoblast (HOb) spheroids and evaluate the biological response to its association with Bone Morphogenetic Protein 2 (rhBMP-2) in rat calvaria. PLA scaffolds were produced via 3D printing, soaked in simulated body fluid (SBF) solution to promote apatite deposition, and characterized by physical-chemical, morphological, and mechanical properties. PLA-CaP scaffolds with interconnected porous and mechanical properties suitable for bone repairing were produced with reproducibility. The in vitro biological response was assessed with human primary osteoblast spheroids. Increased cell adhesion and the rise of in vitro release of growth factors (Platelet-Derived Growth Factor (PDGF), Basic Fibroblast Growth Factor (bFGF), Vascular Endothelial Growth Factor (VEGF) was observed for PLA-CaP scaffolds, when pre-treated with fetal bovine serum (FBS). This pre-treatment with FBS was done in a way to enhance the adsorption of serum proteins, increasing the number of bioactive sites on the surface of scaffolds, and to partially mimic in vivo interactions. The in vivo analysis was conducted through the implantation of 3D printed PLA scaffolds either alone, coated with apatite (PLA-CaP) or PLA-CaP loaded with rhBMP-2 on critical-sized defects (8 mm) of rat calvaria. PLA-CaP+rhBMP2 presented higher values of newly formed bone (NFB) than other groups at all in vivo experimental periods (p < 0.05), attaining 44.85% of NFB after six months. These findings indicated two new potential candidates as alternatives to autogenous bone grafts for long-term treatment: (i) 3D-printed PLA-CaP scaffold associated with spheroids, since it can reduce the time of repair in situ by expression of biomolecules and growth factors; and (ii) 3D-printed PLA-CaP functionalized rhBMP2 scaffold, a biocompatible, bioactive biomaterial, with osteoconductivity and osteoinductivity.

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3D Printed Model of Extrahepatic Biliary Ducts for Biliary Stent Testing

Materials ◽

10.3390/ma13214788 ◽

2020 ◽

Vol 13 (21) ◽

pp. 4788

Author(s):

Joanna Thomas ◽

Sagar Patel ◽

Leia Troop ◽

Robyn Guru ◽

Nicholas Faist ◽

...

Keyword(s):

Mechanical Properties ◽

Computer Aided Design ◽

Bile Ducts ◽

Biliary Stent ◽

Metal Stents ◽

In Vitro Testing ◽

Stent Deployment ◽

3D Print ◽

3D Printed

Several inflammatory conditions of the bile ducts cause strictures that prevent the drainage of bile into the gastrointestinal tract. Non-pharmacological treatments to re-establish bile flow include plastic or self-expanding metal stents (SEMs) that are inserted in the bile ducts during endoscopic retrograde cholangiopancreatography (ERCP) procedures. The focus of this study was to 3D print an anatomically accurate model of the extrahepatic bile ducts (EHBDs) with tissue-like mechanical properties to improve in vitro testing of stent prototypes. Following generation of an EHBD model via computer aided design (CAD), we tested the ability of Formlabs SLA 3D printers to precisely print the model with polymers selected based on the desired mechanical properties. We found the printers were reliable in printing the dimensionally accurate EHBD model with candidate polymers. Next, we evaluated the mechanical properties of Formlabs Elastic (FE), Flexible (FF), and Durable (FD) resins pre- and post-exposure to water, saline, or bile acid solution at 37 °C for up to one week. FE possessed the most bile duct-like mechanical properties based on its elastic moduli, percent elongations at break, and changes in mass under all liquid exposure conditions. EHBD models printed in FE sustained no functional damage during biliary stent deployment or when tube connectors were inserted, and provided a high level of visualization of deployed stents. These results demonstrate that our 3D printed EHBD model facilitates more realistic pre-clinical in vitro testing of biliary stent prototypes.

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Studies on biodegradable poly(hexano-6-lactone) fibers. Part 3. Enzymatic degradation in vitro (IUPAC Technical Report)

Pure and Applied Chemistry ◽

10.1351/pac200274050869 ◽

2002 ◽

Vol 74 (5) ◽

pp. 869-880 ◽

Cited By ~ 31

Author(s):

Toshio Hayashi ◽

Kazuo Nakayama ◽

Masatsugu Mochizuki ◽

Toshiro Masuda

Keyword(s):

Mechanical Properties ◽

Weight Loss ◽

Enzymatic Degradation ◽

Strength Loss ◽

Enzymatic Digestion ◽

Dynamic Mechanical Properties ◽

Sonic Velocity ◽

Technical Report ◽

Biodegradable Poly

Poly(hexano-6-lactone) (PCL*) fibers were enzymatically degraded by a hydrolase in vitro. The extent of degradation of PCL fibers was examined by weight loss, mechanical properties loss such as tensile strength and ultimate elongation decreases, and visual observations by scanning electron microscopy. The in vitro degradation of PCL fibers was carried out using a lipoprotein lipase (Lipase-PS) as a hydrolase. The kinetic study on the weight loss of PCL fiber accompanying the enzymatic degradation suggested that the degradation of PCL fibers gradually takes place from the surface, not bulk degradation. The rate of degradation was found to depend on draw ratio and crystallinity of the PCL fibers. The strength loss of PCL fibers in the course of degradation took place faster than the weight loss of PCL fibers. Sonic velocity measurements as well as dynamic mechanical properties of PCL fibers were also examined as a function of weight loss of sample fibers with Lipase-PS treatments. It was shown that sonic velocity and value of loss tangent d changed steeply for undrawn PCL fiber in the first step with enzymatic digestion.

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Powder Loading Effects on the Physicochemical and Mechanical Properties of 3D Printed Poly Lactic Acid/Hydroxyapatite Biocomposites

International Journal of Bioprinting ◽

10.18063/ijb.v7i1.326 ◽

2021 ◽

Vol 7 (1) ◽

pp. 326

Author(s):

Cyron Lego Custodio ◽

Phoebeliza Jane M. Broñola ◽

Sharyjel R.Cayabyab ◽

Vivian U. Lagura ◽

Josefina R. Celorico ◽

...

Keyword(s):

Mechanical Properties ◽

Fused Deposition Modeling ◽

Poly Lactic Acid ◽

Modeling Technology ◽

Fused Deposition ◽

Twin Screw ◽

Loading Effects ◽

3D Printed ◽

Sbf Solution

This study presents the physicochemical and mechanical behavior of incorporating hydroxyapatite (HAp) with polylactic acid (PLA) matrix in 3D printed PLA/HAp composite materials. Effects of powder loading to the composition, crystallinity, morphology, and mechanical properties were observed. HAp was synthesized from locally sourced nanoprecipitated calcium carbonate and served as the filler for the PLA matrix. The 0, 5, 10, and 15 wt. % HAp biocomposite filaments were formed using a twin-screw extruder. The resulting filaments were 3D printed in an Ultimaker S5 machine utilizing a fused deposition modeling technology. Successful incorporation of HAp and PLA was observed using infrared spectroscopy and X-ray diffraction (XRD). The mechanical properties of pure PLA had improved on the incorporation of 15% HAp; from 32.7 to 47.3 MPa in terms of tensile strength; and 2.3 to 3.5 GPa for stiffness. Moreover, the preliminary in vitro bioactivity test of the 3D printed PLA/HAp biocomposite samples in simulated body fluid (SBF) indicated varying weight gains and the presence of apatite species’ XRD peaks. The HAp particles embedded in the PLA matrix acted as nucleation sites for the deposition of salts and apatite species from the SBF solution

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Plasma assisted design of biocompatible 3D printed PCL/silver nanoparticle scaffolds: in vitro and in vivo analyses

Materials Advances ◽

10.1039/d1ma00444a ◽

2021 ◽

Author(s):

Neethu Ninan ◽

Blessy Joseph ◽

Rahul Madathiparambil Visalakshan ◽

Richard Bright ◽

Clement Denoual ◽

...

Keyword(s):

Mechanical Properties ◽

Tissue Engineering ◽

3D Printing ◽

Silver Nanoparticle ◽

Medical Treatments ◽

3D Printed

3D printing provides numerous opportunities for designing tissue engineering constructs with intricate porosity, geometry and favourable mechanical properties and has the potential to revolutionize medical treatments.

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