In Vivo Mechanical Characterization of Micro-Specimens Using a Novel Micro-Electro-Mechanical System

2011 ◽  
Author(s):  
Leila Ladani ◽  
Daniel Preston
Keyword(s):  
Mechanical Properties ◽  
Biological Tissues ◽  
Micro Electro Mechanical System ◽  
The Body ◽  
Mechanical Degradation ◽  
Element Analysis ◽  
Rigid Frame

Mechanical probing, stimulation and characterization of tissues are of the most challenging areas of engineering due to limitations of working with bio specimens. Understanding the bio-mechanics of tissues could potentially help to understand mechanical degradation of biological tissues due to disease or change in physiological condition of the body. Biomechanical processes at the microscopic level have become increasingly recognized as an important factor in different biological conditions. In many of these conditions analyzing biomechanics of tissues at microscale in vivo or in vitro will provide invaluable information on microenvironment and physiological parameters that affect the microenvironment and mechanical properties. To address the issue of measuring mechanical properties at microscale, an electroactive-based micro-electromechanical machine is designed. The device is comprised of two electroactive (piezoelectric) micro-elements mounted on a rigid frame. Electrical activation of one of the elements causes it to expand and induce a stress in the intervening micro-specimen. The response of the microspecimen to the stress is measured by the deformation and thereby voltage/resistance induced in the second electro-active element. Figure 1 shows the device design and architecture. Analytical analysis and multiphysics finite element analysis (FEA) are used to prove the concept. A summary of the results are shown in the next sections.

scholarly journals Injectable non-leaching tissue-mimetic bottlebrush elastomers as an advanced platform for reconstructive surgery

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Erfan Dashtimoghadam ◽  
Farahnaz Fahimipour ◽  
Andrew N. Keith ◽  
Foad Vashahi ◽  
Pavel Popryadukhin ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Reconstructive Surgery ◽  
Biomedical Applications ◽  
The Body ◽  
Surrounding Tissue ◽  
Curing Time ◽  
Materials Used ◽  
Significant Health

AbstractCurrent materials used in biomedical devices do not match tissue’s mechanical properties and leach various chemicals into the body. These deficiencies pose significant health risks that are further exacerbated by invasive implantation procedures. Herein, we leverage the brush-like polymer architecture to design and administer minimally invasive injectable elastomers that cure in vivo into leachable-free implants with mechanical properties matching the surrounding tissue. This strategy allows tuning curing time from minutes to hours, which empowers a broad range of biomedical applications from rapid wound sealing to time-intensive reconstructive surgery. These injectable elastomers support in vitro cell proliferation, while also demonstrating in vivo implant integrity with a mild inflammatory response and minimal fibrotic encapsulation.

scholarly journals Injectable Non-leaching Tissue-mimetic Bottlebrush Elastomers: A New Platform for Advancing Reconstructive Surgery

2020 ◽  
Author(s):  
Erfan Dashtimoghadam ◽  
Farahnaz Fahimipour ◽  
Andrew Keith ◽  
Foad Vashahi ◽  
Pavel Popryadukhin ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Reconstructive Surgery ◽  
Biomedical Applications ◽  
The Body ◽  
Surrounding Tissue ◽  
Curing Time ◽  
Materials Used ◽  
Significant Health

Abstract Current materials used in biomedical devices do not match tissue’s mechanical properties and leach various chemicals into the body. These deficiencies pose significant health risks that are further exacerbated by invasive implantation procedures. Herein, we leverage the brush-like polymer architecture to design and administer minimally invasive injectable elastomers that cure in vivo into leachable-free implants with mechanical properties matching the surrounding tissue. This strategy allows tuning curing time from minutes to hours, which empowers a broad range of biomedical applications from rapid wound sealing to time-intensive reconstructive surgery. These injectable elastomers support in vitro cell proliferation, while also demonstrating in vivo implant integrity with a mild inflammatory response and minimal fibrotic encapsulation.

scholarly journals Molecular and functional characterization of somatostatin-type signalling in a deuterostome invertebrate

Open Biology ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 200172
Author(s):  
Ya Zhang ◽  
Luis Alfonso Yañez Guerra ◽  
Michaela Egertová ◽  
Cleidiane G. Zampronio ◽  
Alexandra M. Jones ◽  
...  
Keyword(s):  
Functional Characterization ◽  
The Body ◽  
Pharmacological Characterization ◽  
Cardiac Stomach ◽  
Physiological Processes ◽  
Pharmacological Tests ◽  
The Central Nervous System

Somatostatin (SS) and allatostatin-C (ASTC) are structurally and evolutionarily related neuropeptides that act as inhibitory regulators of physiological processes in mammals and insects, respectively. Here, we report the first molecular and functional characterization of SS/ASTC-type signalling in a deuterostome invertebrate—the starfish Asterias rubens (phylum Echinodermata). Two SS/ASTC-type precursors were identified in A. rubens (ArSSP1 and ArSSP2) and the structures of neuropeptides derived from these proteins (ArSS1 and ArSS2) were analysed using mass spectrometry. Pharmacological characterization of three cloned A. rubens SS/ASTC-type receptors (ArSSR1–3) revealed that ArSS2, but not ArSS1, acts as a ligand for all three receptors. Analysis of ArSS2 expression in A. rubens using mRNA in situ hybridization and immunohistochemistry revealed stained cells/fibres in the central nervous system, the digestive system (e.g. cardiac stomach) and the body wall and its appendages (e.g. tube feet). Furthermore, in vitro pharmacological tests revealed that ArSS2 causes dose-dependent relaxation of tube foot and cardiac stomach preparations, while injection of ArSS2 in vivo causes partial eversion of the cardiac stomach. Our findings provide new insights into the molecular evolution of SS/ASTC-type signalling in the animal kingdom and reveal an ancient role of SS-type neuropeptides as inhibitory regulators of muscle contractility.

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

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.

Spline Based Microstructural Mapping for Soft Biological Tissues: Application to Aortic Valves

2013 ◽  
Author(s):  
A. Aggarwal ◽  
V. S. Aguilar ◽  
C. H. Lee ◽  
G. Ferrari ◽  
J. H. Gorman ◽  
...  
Keyword(s):  
Aortic Valve ◽  
Computer Aided Design ◽  
Biological Tissues ◽  
Mechanical Tests ◽  
Aortic Valves ◽  
Element Analysis ◽  
Tissue Microstructure ◽  
Forward And Inverse Modeling

Splines are the standard tools in computer aided design for geometric representations and have been recently integrated into the finite element analysis of structures and fluids [1]. As the biomedical engineering is making progress, there is a need for an integrated tool for expanding the geometrical representation to include the microstructural details specific to soft tissue, e.g. fiber alignment, orientation, crimp and stiffness. In this work, a spline-based method is presented for aortic valves which facilitates mapping of the fiber structure from any aortic valve specimen to any other aortic valve geometry through a common parameter space. This techniques also has the ability to calculate mean tissue microstructure of representative population. Also strain and pre-strain from in-vivo state to the in-vitro state, where all the mechanical tests are done, are calculated for forward and inverse modeling of aortic valves.

scholarly journals Design, Preparation, and Characterization of Dioscin Nanosuspensions and Evaluation of Their Protective Effect against Carbon Tetrachloride-Induced Acute Liver Injury in Mice

2019 ◽  
Vol 2019 ◽  
pp. 1-16 ◽  
Author(s):  
Hong-Ye JU ◽  
Kun-Xia Hu ◽  
Guo-Wang Zhao ◽  
Zhi-Shu Tang ◽  
Xiao Song
Keyword(s):  
Particle Size ◽  
Protective Effect ◽  
Soybean Lecithin ◽  
Chemical Properties ◽  
Spherical Shape ◽  
Positive Control ◽  
The Body

The purpose of this study was to prepare a dioscin nanosuspension (Dio-NS) that has a better distance and high solubility for oral administration and to evaluate its hepatoprotective effects. Optimal primary manufacture parameters, including shear time, shear speed, emulation temperature, pressure, and cycles of homogenization, were determined by single-factor experiments. The concentrations of dioscin, SDS, and soybean lecithin were optimized using the central composite design-response surface method, and their effects on the mean particle size (MPS) and particle size distribution of Dio-NS were investigated. Characterization of the Dio-NS formulations included examinations of the surface morphology and physical status of dioscin in Dio-NS, the stability of Dio-NS at different temperatures, in vitro solubility, and liver protective effect in vivo. Under optimal conditions, Dio-NS had an MPS of 106.72 nm, polydispersity index of 0.221, and zeta potential of −34.27 mV. Furthermore, the proportion of dioscin in Dio-NS was approximately 21.26%. The observation of particles with a spherical shape and the disappearance of crystalline peaks indicated that the physical and chemical properties of Dio-NS were altered. Furthermore, we observed that the dissolution of Dio-NS was superior to that of a physical mixture and Dio-GZF. Moreover, Dio-NS was demonstrated to have a protective effect against CCl4-induced acute liver damage in mice that was equivalent to that of silymarin (a positive control drug) at the same dose. The good hepatoprotective effect of our Dio-NS preparation can provide a theoretical basis for investigating its absorption mechanisms in the body.

scholarly journals In vivo characterization of chick embryo mesoderm by optical coherence tomography assisted microindentation

2020 ◽  
Author(s):  
Marica Marrese ◽  
Nelda Antonovaité ◽  
Ben K.A. Nelemans ◽  
Ariana Ahmadzada ◽  
Davide Iannuzzi ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Optical Coherence Tomography ◽  
Storage Modulus ◽  
Biological Tissues ◽  
Surrounding Tissue ◽  
Optical Coherence ◽  
Presomitic Mesoderm ◽  
New Instrument

AbstractEmbryos are growing organisms with highly heterogeneous properties in space and time. Understanding the mechanical properties is a crucial prerequisite for the investigation of morphogenesis. During the last ten years, new techniques have been developed to evaluate the mechanical properties of biological tissues in vivo. To address this need, we employed a new instrument that, via the combination of micro-indentation with Optical Coherence Tomography (OCT), allows us to determine both, the spatial distribution of mechanical properties of chick embryos and the structural changes in real-time provided by OCT. We report here the stiffness measurements on live chicken mesoderm during somite formation, from the mesenchymal tailbud to the epithelialized somites. The storage modulus of the mesoderm increases from (176±18) Pa in the tail up to (716±117) Pa in the somitic region. The midline has a storage modulus of (947±111) Pa in the caudal presomitic mesoderm, indicating a stiff rod along the body axis, which thereby mechanically supports the surrounding tissue. The difference in stiffness between midline and presomitic mesoderm decreases as the mesoderm forms somites. The viscoelastic response of the somites develops further until somite IV, which is commensurate with the slow process of epithelization of somites between S0 and SIV.Overall, this study provides an efficient method for the biomechanical characterization of soft biological tissues in vivo and shows that the mechanical properties strongly relate to different morphological features of the investigated regions.

A Comparison of Magnetometry and Relaxometry Measures of Magnetic Nanoparticles Deposited in Biological Samples

2015 ◽  
Vol 31 ◽  
pp. 129-137 ◽  
Author(s):  
Ana Lorena Urbano-Bojorge ◽  
Nazario Félix-González ◽  
Tamara Fernández ◽  
Francisco del Pozo-Guerrero ◽  
Milagros Ramos ◽  
...  
Keyword(s):  
Magnetic Nanoparticles ◽  
Magnetic Nanostructures ◽  
High Sensitivity ◽  
Biological Tissues ◽  
The Body ◽  
In Vivo Studies ◽  
Gradient Field ◽  
Measurement Protocol

The Alternating Gradient Field Magnetometer (AGFM) is an instrument whose high sensitivity (10-8 emu) allows the detection of small amounts of magnetic nanoparticles (MNPs) with high accuracy. Over the last few years, different magnetic techniques have been used for in vitro measurements of magnetic nanostructures inside biological tissues. However, in vivo studies about their distribution within the body are very scarce because their dispersion, after being delivered, reduces their magnetic signal and hinders detection. In this paper we compare the longitudinal relaxation time (T1) and magnetization measurements in mice's biological tissues for the tracking of MNPs after of an injection of iron oxide nanoparticles. Furthermore, we have correlated the AGFM data with Fast Field Cycling NMR Relaxometry (FFCNMR Relaxometry) measurements with histological analysis. The results have demonstrated that these techniques are useful for detecting minute amounts of MNPs in excised organs after in-vivo comparable to other more conventional techniques for the measurement of MNPs biodistribution and clearance. Details about the preparation of the in vivo samples, measurement protocol and statistical data processing are given.

scholarly journals A new hyperelastic model for the multi-axial deformation of blood clots occlusion in vessels

2020 ◽  
Author(s):  
Behrooz Fereidoonnezhad ◽  
Kevin Mattheus Moerman ◽  
Sarah Johnson ◽  
Ray McCarthy ◽  
Patrick McGarry
Keyword(s):  
Mechanical Properties ◽  
Axial Deformation ◽  
Proposed Model ◽  
Nonlinear Stress ◽  
Blood Clots ◽  
Hyperelastic Model

Mechanical thrombectomy can be significantly affected by the mechanical properties of the occluding thrombus. In this study we provide the first characterization of the volumetric behaviour of blood clots. We propose a new hyperelastic model for the volumetric and isochoric deformation of clot. We demonstrate that the proposed model provides significant improvements over established models in terms of accurate prediction of nonlinear stress-strain and volumetric behaviours of low and high haematocrit clots. We perform a rigorous investigation of the factors that govern clot occlusion of a tapered vessel. The motivation for such an analysis is two-fold: (i) the role of clot composition on the in-vivo occlusion location is an open clinical question that has significant implications for thrombectomy procedures; (ii) in-vitro measurement of occlusion location in an engineered tapered tube can be used as a quick and simple methodology to assess the mechanical properties/compositions of clots. Simulations demonstrate that both isochoric and volumetric behaviour of clots are key determinants of clot lodgement location, in addition to clot-vessel friction. The proposed formulation is shown to provide accurate predictions of in-vitro measurement of clot occlusion location in a silicone tapered vessel, in addition to accurately predicting the deformed shape of the clot.

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