scholarly journals Mechanical Enhancement of Cytocompatible 3D Scaffolds, Consisting of Hydroxyapatite Nanocrystals and Natural Biomolecules, Through Physical Cross-Linking

2020 ◽  
Vol 7 (3) ◽  
pp. 96
Author(s):  
Despoina Brasinika ◽  
Elias P. Koumoulos ◽  
Kyriaki Kyriakidou ◽  
Eleni Gkartzou ◽  
Maria Kritikou ◽  
...  
Keyword(s):  
Elastic Modulus ◽  
Cell Attachment ◽  
Great Promise ◽  
Porous Network ◽  
Mechanical Reinforcement ◽  
Experimental Conditions ◽  
Tissue Properties ◽  
Human Osteosarcoma Cells ◽  
Hydroxyapatite Nanocrystals ◽  
Physical Crosslinking

Bioinspired scaffolds mimicking natural bone-tissue properties holds great promise in tissue engineering applications towards bone regeneration. Within this work, a way to reinforce mechanical behavior of bioinspired bone scaffolds was examined by applying a physical crosslinking method. Scaffolds consisted of hydroxyapatite nanocrystals, biomimetically synthesized in the presence of collagen and l-arginine. Scaffolds were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy (SEM), microcomputed tomography, and nanoindentation. Results revealed scaffolds with bone-like nanostructure and composition, thus an inherent enhanced cytocompatibility. Evaluation of porosity proved the development of interconnected porous network with bimodal pore size distribution. Mechanical reinforcement was achieved through physical crosslinking with riboflavin irradiation, and nanoindentation tests indicated that within the experimental conditions of 45% humidity and 37 °C, photo-crosslinking led to an increase in the scaffold’s mechanical properties. Elastic modulus and hardness were augmented, and specifically elastic modulus values were doubled, approaching equivalent values of trabecular bone. Cytocompatibility of the scaffolds was assessed using MG63 human osteosarcoma cells. Cell viability was evaluated by double staining and MTT assay, while attachment and morphology were investigated by SEM. The results suggested that scaffolds provided a cell friendly environment with high levels of viability, thus supporting cell attachment, spreading and proliferation.

scholarly journals Applying biophysical models to understand the role of white matter in cognitive development

2018 ◽  
Author(s):  
Elizabeth Huber ◽  
Rafael Neto Henriques ◽  
Julia P. Owen ◽  
Ariel Rokem ◽  
Jason D. Yeatman
Keyword(s):  
White Matter ◽  
Cognitive Development ◽  
Diffusion Mri ◽  
Reading Skill ◽  
Great Promise ◽  
Model Parameters ◽  
Biophysical Modeling ◽  
Tissue Properties ◽  
Biophysical Models ◽  
Specific Tissue

AbstractDiffusion MRI (dMRI) holds great promise for illuminating the biological changes that underpin cognitive development. The diffusion of water molecules probes the cellular structure of brain tissue, and biophysical modeling of the diffusion signal can be used to make inferences about specific tissue properties that vary over development or predict cognitive performance. However, applying these models to study development requires that the parameters can be reliably estimated given the constraints of data collection with children. Here we collect repeated scans using a multi-shell diffusion MRI protocol in a group of children (ages 7-12) and use two popular biophysical models to characterize axonal properties. We first assess the scan-rescan reliability of model parameters and show that axon water faction can be reliably estimated from a relatively fast acquisition, without applying spatial smoothing or de-noising. We then investigate developmental changes in the white matter, and individual differences in white matter that correlate with reading skill. Specifically, we test the hypothesis that previously reported correlations between reading skill and diffusion anisotropy in the corpus callosum reflect increased axon density in poor readers. Both models support this interpretation, highlighting the utility of biophysical models for testing specific hypotheses about cognitive development.

scholarly journals A Facile Colorimetric Method For Ultra-Rapid And Sensitive Detection of Copper Ions In Water

2021 ◽  
Author(s):  
Lei Chen ◽  
Yan Li ◽  
Ping Sun ◽  
Hualin Chen ◽  
He Li ◽  
...  
Keyword(s):  
Color Change ◽  
Copper Ions ◽  
Colorimetric Method ◽  
Ethanol Solution ◽  
Sensitive Detection ◽  
World Health ◽  
Great Promise ◽  
Experimental Conditions ◽  
Interesting Phenomenon ◽  
Health Organization

Abstract It is of great meaning to develop a facile, reliable and sensitive method to detect copper ions in water. In the study, a facile method has been developed for rapid and sensitive detection of Cu2+. An interesting phenomenon has been observed that 3,3',5,5'-tetramethylbenzidine (TMB) ethanol solution can be extremely fast passed from colorless to yellow once Cu2+ ions are added. It easily occurs to us that Cu2+ can be quantitatively determined via the absorbance at 904 nm of the color changed TMB solution. More importantly, some specific anions (Cl- , Br- ) can significantly enhance the absorption intensity. Under the optimized experimental conditions, this method exhibits a good linear response range for Cu2+ from 0.5 to 100 μM, with the detection limit of 93 nM. Moreover, the possible detection principle has been explored. It is worth mentioning that the color change can be clearly observed by naked eyes for the detection of 1 μM Cu2+, which is far below the threshold limit of Cu2+ in drinking water suggested by World Health Organization. It means that this method possess great promise for on-site Cu2+ detection.

Different mechanisms in the attachment of cells to native and denatured collagen

1979 ◽  
Vol 38 (1) ◽  
pp. 267-281
Author(s):  
S.L. Schor ◽  
J. Court
Keyword(s):  
Cell Attachment ◽  
Experimental Conditions ◽  
Cell Matrix ◽  
Matrix Interactions ◽  
Independent Mechanism ◽  
Cell Matrix Interactions ◽  
Serum Dependent ◽  
Kinetics Of ◽  
Dependent Mechanism

The attachment of cells to collagen has been reported previously to require the presence of serum and the particular serum protein involved in this process, variously known as CIG, CAP or fibronectin, has been isolated. This conclusion that cell attachment to collagen requires serum (or more precisely, fibronectin) is based on experiments measuring the kinetics of cell attachment to films of collagen. We have measured the kinetics of attachment of HeLa and attachment to films of collagen-containing substrata under a variety of experimental conditions and present evidence that the serum-dependent mechanism of cell attachment described by others is actually only the case for films of denatured collagen, while cell attachment to native collagen fibres occurs by a different, serum-independent, mechanism. The possible relevance of these findings to cell-matrix interactions in vivo is discussed.

Force and Compression Analysis for Rigid Retaining Walls with EPS Buffer

2011 ◽  
Vol 243-249 ◽  
pp. 959-962
Author(s):  
De Ling Wang ◽  
Li Guo
Keyword(s):  
Elastic Modulus ◽  
Retaining Wall ◽  
Retaining Walls ◽  
Great Promise ◽  
Static Loads ◽  
Physical Test ◽  
Eps Geofoam ◽  
Backfill Soil ◽  
Vibration Loads ◽  
Simulation Results

In this paper, the force against rigid retaining walls from backfill soil under static loads and vibration loads is analyzed within three cases. The first case is an ordinary retaining wall without expanded polystyrene (EPS) geofoam buffer. In the second and the third case, a layer of vertical EPS buffer with different density and elastic modulus is placed between a rigid retaining wall and backfill soil. Numerical simulation results show that the force against the same retaining wall in the treated cases is less than that in the untreated case, under both static loads and vibration loads. Moreover, the compression of different EPS buffer is studied. Under vibration excitation, when the density and elastic modulus of EPS buffer decreases, its compression increases and more wall force is mitigated. Simulation results accord with the physical shaking table test data. Numerical results and physical test demonstrate that EPS geofoam seismic buffers hold great promise to reduce loads against rigid retaining wall structures, especially earthquake-induced dynamic loads.

Characterizing the mechanical properties of tropoelastin protein scaffolds

2013 ◽  
Vol 1569 ◽  
pp. 45-50 ◽  
Author(s):  
Audrey C. Ford ◽  
Hans Machula ◽  
Robert S. Kellar ◽  
Brent A. Nelson
Keyword(s):  
Mechanical Properties ◽  
Elastic Modulus ◽  
Cell Attachment ◽  
Mechanical Design ◽  
Protein Composition ◽  
Tissue Scaffolds ◽  
Surrounding Tissue ◽  
Protein Scaffolds ◽  
Initial Stiffness ◽  
Rate Dependent

ABSTRACTThis paper reports on mechanical characterization of electrospun tissue scaffolds formed from varying blends of collagen and human tropoelastin. The electrospun tropoelastin-based scaffolds have an open, porous structure conducive to cell attachment and have been shown to exhibit strong biocompatibility, but the mechanical character is not well known. Mechanical properties were tested for scaffolds consisting of 100% tropoelastin and 1:1 tropoelastin-collagen blends. The results showed that the materials exhibited a three order of magnitude change in the initial elastic modulus when tested dry vs. hydrated, with moduli of 21 MPa and 0.011 MPa respectively. Noncrosslinked and crosslinked tropoelastin scaffolds exhibited the same initial stiffness from 0 to 50% strain, and the noncrosslinked scaffolds exhibited no stiffness at strains >∼50%. The elastic modulus of a 1:1 tropoelastin-collagen blend was 50% higher than that of a pure tropoelastin scaffold. Finally, the 1:1 tropoelastin-collagen blend was five times stiffer from 0 to 50% strain when strained at five times the ASTM standard rate. By systematically varying protein composition and crosslinking, the results demonstrate how protein scaffolds might be manipulated as customized biomaterials, ensuring mechanical robustness and potentially improving biocompatibility through minimization of compliance mismatch with the surrounding tissue environment. Moreover, the demonstration of strain-rate dependent mechanical behavior has implications for mechanical design of tropoelastin-based tissue scaffolds.

scholarly journals A Precised Surface Modification of Hydroxyapatite with Poly(methylmethacrylate) for Tissue Engineering & Regenerative Medicine

2019 ◽  
Vol 31 (3) ◽  
pp. 545-550
Author(s):  
Trinh Duy Nguyen ◽  
Phu Thuong Nhan Nguyen ◽  
Thien Hien Tran ◽  
Md. Rafiqul Islam ◽  
Kwon Taek Lim ◽  
...  
Keyword(s):  
Tissue Engineering ◽  
Regenerative Medicine ◽  
Radical Polymerization ◽  
Colloidal Stability ◽  
Hybrid Nanocomposites ◽  
Great Promise ◽  
Dsc Studies ◽  
One Step ◽  
Grafting From ◽  
Hydroxyapatite Nanocrystals

The poly(methylmethacrylate) (PMMA) grafted biocompatible hydroxyapatite nanocrystals (HAPs) hybrid nanocomposites (PMMA-g-HAPs) were synthesized by employing surface thiol-lactam initiated radical polymerization (TLIRP) through grafting from strategy. At first, the surface of HAPs was functionalized by 3-mercaptopropyl-trimethoxysilane in one-step process to prepare thiol immobilized HAPs (HAPs-SH). Subsequently, a controlled radical polymerization of MMA by using two component initiating system comprising of HAPs-SH and butyrolactam (BL) successfully afforded PMMA-g-HAPs nanocomposites. The resulting structure and morphological feature of nanocomposites was systematically characterized by FT-IR and XRD analyses. GPC studies of cleaved polymers from nanocomposites of different time revealed that the grafting polymerization from the surface of HAP was well controlled in nature. Moreover, the thermal property of the PMMA was found to be improved by incorporation of inorganic HAP nanoparticles in the polymer matrix as revealed by TGA and DSC studies. The colloidal stability of the synthesized nanocomposites was observed to be exceptionally good in organic solvents as suggested by the time dependent monitoring using UV-visible spectroscopy and captured digital photographs. The synthesized nanocomposites show a great promise for the safe application in tissue engineering and regenerative medicine.

scholarly journals Two Birds with One Stone: Preparation of 4, 4-Diaminodiphenylmethane Functionalized GO@SiO2 with Mechanical Reinforcement and UV Shielding Properties and Its Application in Thermoplastic Polyurethane

Polymers ◽  
2021 ◽  
Vol 13 (23) ◽  
pp. 4220
Author(s):  
Guoxin Ding ◽  
Hongxu Tai ◽  
Chuanxin Chen ◽  
Chenfeng Sun ◽  
Zhongfeng Tang
Keyword(s):  
Thermoplastic Polyurethane ◽  
High Strength ◽  
Great Promise ◽  
Functional Coatings ◽  
Mechanical Reinforcement ◽  
Functionalized Graphene Oxide ◽  
Uv Shielding ◽  
Amidation Reaction ◽  
Weather Resistance ◽  
Silica Dioxide

This study prepared 4,4-diaminodiphenylmethane (DDM)-functionalized graphene oxide (GO)@silica dioxide (SiO2) nano-composites through amidation reaction and low-temperature precipitation. The resulting modified GO, that was DDM−GO@SiO2. The study found that DDM−GO@SiO2 showed good dispersion and compatibility with thermoplastic polyurethane (TPU) substrates. Compared with pure TPU, the tensile strength of the TPU composites increased by 41% to 94.6 MPa at only 0.5 wt% DDM−GO@SiO2. In addition, even when a small amount of DDM−GO@SiO2 was added, the UV absorption of TPU composites increased significantly, TPU composites can achieve a UV shielding efficiency of 95.21% in the UV-A region. These results show that this type of material holds great promise for the preparation of functional coatings and film materials with high strength and weather resistance.

scholarly journals Local and Non-local Effects of Foam Rolling on Passive Soft Tissue Properties and Spinal Excitability

2021 ◽  
Vol 12 ◽  
Author(s):  
Masatoshi Nakamura ◽  
Andreas Konrad ◽  
Ryosuke Kiyono ◽  
Shigeru Sato ◽  
Kaoru Yahata ◽  
...  
Keyword(s):  
Elastic Modulus ◽  
Soft Tissue ◽  
Medial Gastrocnemius ◽  
Plantar Flexors ◽  
Tissue Properties ◽  
Foam Rolling ◽  
Shear Elastic Modulus ◽  
Body Regions ◽  
Passive Torque ◽  
Spinal Excitability

In sports and clinical settings, roller massage (RM) interventions are used to acutely increase range of motion (ROM); however, the underlying mechanisms are unclear. Apart from changes in soft tissue properties (i.e., reduced passive stiffness), neurophysiological alterations such as decreased spinal excitability have been described. However, to date, no study has investigated both jointly. The purpose of this trial was to examine RM’s effects on neurophysiological markers and passive tissue properties of the plantar flexors in the treated (ROLL) and non-treated (NO-ROLL) leg. Fifteen healthy individuals (23 ± 3 years, eight females) performed three unilateral 60-s bouts of calf RM. This procedure was repeated four times on separate days to allow independent assessments of the following outcomes without reciprocal interactions: dorsiflexion ROM, passive torque during passive dorsiflexion, shear elastic modulus of the medial gastrocnemius muscle, and spinal excitability. Following RM, dorsiflexion ROM increased in both ROLL (+19.7%) and NO-ROLL (+13.9%). Similarly, also passive torque at dorsiflexion ROM increased in ROLL (+15.0%) and NO-ROLL (+15.2%). However, there were no significant changes in shear elastic modulus and spinal excitability (p > 0.05). Moreover, significant correlations were observed between the changes in DF ROM and passive torque at DF ROM in both ROLL and NO-ROLL. Changes in ROM after RM appear to be the result of sensory changes (e.g., passive torque at DF ROM), affecting both rolled and non-rolled body regions. Thus, therapists and exercise professionals may consider applying remote treatments if local loading is contraindicated.

scholarly journals Bioactivity and Bone Cell Formation with Poly-ε-Caprolactone/Bioceramic 3D Porous Scaffolds

Polymers ◽  
2021 ◽  
Vol 13 (16) ◽  
pp. 2718
Author(s):  
Po-Kai Juan ◽  
Fang-Yu Fan ◽  
Wei-Chun Lin ◽  
Pei-Bang Liao ◽  
Chiung-Fang Huang ◽  
...  
Keyword(s):  
Elastic Modulus ◽  
Cell Attachment ◽  
Ph Value ◽  
Ceramic Powder ◽  
High Ratio ◽  
Porous Scaffolds ◽  
Alp Activity ◽  
Mg63 Cells ◽  
Human Cancellous Bone

This study applied poly-ε-caprolactone (PCL), a biomedical ceramic powder as an additive (nano-hydroxyapatite (nHA) or β-tricalcium diphosphate (β-TCP)), and sodium chloride (NaCl) and ammonium bicarbonate ((NH4)HCO3) as porogens; these stuffs were used as scaffold materials. An improved solvent-casting/particulate-leaching method was utilized to fabricate 3D porous scaffolds. In this study we examined the physical properties (elastic modulus, porosity, and contact angle) and degradation properties (weight loss and pH value) of the 3D porous scaffolds. Both nHA and β-TCP improved the mechanical properties (elastic modulus) of the 3D porous scaffolds. The elastic modulus (0.15~1.865 GPa) of the various composite scaffolds matched that of human cancellous bone (0.1~4.5 GPa). Osteoblast-like (MG63) cells were cultured, a microculture tetrazolium test (MTT) was conducted and alkaline phosphatase (ALP) activity of the 3D porous scaffolds was determined. Experimental results indicated that both nHA and β-TCP powder improved the hydrophilic properties of the scaffolds. The degradation rate of the scaffolds was accelerated by adding nHA or β-TCP. The MTT and ALP activity tests indicated that the scaffolds with a high ratio of nHA or β-TCP had excellent properties of in vitro biocompatibility (cell attachment and proliferation).

Mathematical Simulation and Parametric Study of Flow of a Microbicidal Gel Between Elastic Boundaries

2011 ◽  
Author(s):  
Sunil Karri ◽  
Sarah L. Kieweg
Keyword(s):  
Active Ingredient ◽  
Flow Behavior ◽  
Great Promise ◽  
Delivery Vehicle ◽  
Polymeric Liquid ◽  
Vaginal Tissue ◽  
Tissue Properties ◽  
Sexually Transmitted ◽  
Polymeric Delivery ◽  
External Forces

Topical microbicides, the next generation prevention tool for HIV and other sexually transmitted pathogens, hold great promise if the target vaginal or rectal epithelium is coated effectively. A microbicide consists of an active ingredient within a polymeric delivery vehicle (e.g. polymeric liquid or ‘gel’). Most research in the field of microbicides has been limited to the development of an active ingredient and many microbicidal trails have failed in the past. Thus, there is a need to design a delivery vehicle that optimizes the efficacy of a microbicidal agent. The effectiveness of the gel depends on the gel’s rheological properties as well as the vaginal tissue properties, vaginal geometry, and external forces like gravity. A good design must take these factors in to consideration and a better understanding of the gel’s flow behavior over the epithelium is important before proceeding with clinical trials.

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