Physical characterization and in vitro evaluation of 3D printed hydroxyapatite, tricalcium phosphate, zirconia, alumina, and SiAlON structures made by lithographic ceramic manufacturing

MRS Advances ◽  
2020 ◽  
Vol 5 (46-47) ◽  
pp. 2419-2428
Author(s):  
Alexander K. Nguyen ◽  
Peter L. Goering ◽  
Shelby A. Skoog ◽  
Roger J. Narayan
Keyword(s):  
Tricalcium Phosphate ◽  
Force Microscopy ◽  
Atomic Force ◽  
3D Printed ◽  
Ceramic Manufacturing ◽  
Surface Morphologies ◽  
Combination Of Material ◽  
Amorphous Character ◽  
Cells Cultured

AbstractIn this study, lithographic ceramic manufacturing was used to create solid chips out of hydroxyapatite, tricalcium phosphate, zirconia, alumina, and SiAlON ceramic. X-ray powder diffraction of each material confirmed that the chips were crystalline, with little amorphous character that could result from remaining polymeric binder, and were composed entirely out of the ceramic feedstock. Surface morphologies and roughnesses were characterized using atomic force microscopy. Human bone marrow stem cells cultured with osteogenic supplements on each material type expressed alkaline phosphatase levels, an early marker of osteogenic differentiation, on par with cells cultured on a glass control. However, cells cultured on the tricalcium phosphate-containing material expressed lower levels of ALP suggesting that osteoinduction was impaired on this material. Further analyses should be conducted with these materials to identify underlying issues of the combination of material and analysis method.

3D-Printed Polycaprolactone Reinforced Hydrogel as an Artificial TMJ Disc

2021 ◽  
pp. 002203452110006
Author(s):  
N. Jiang ◽  
Y. Yang ◽  
L. Zhang ◽  
Y. Jiang ◽  
M. Wang ◽  
...  
Keyword(s):  
Tensile Creep ◽  
Artificial Disc ◽  
Joint Stability ◽  
Condylar Cartilage ◽  
Force Microscopy ◽  
Atomic Force ◽  
Tmj Disc ◽  
Defect Repair ◽  
3D Printed ◽  
Surface Morphologies

The replacement of a damaged temporomandibular joint (TMJ) disc remains a long-standing challenge in clinical settings. No study has reported a material with comprehensively excellent properties similar to a natural TMJ disc. In this work, we designed a novel artificial TMJ disc using polyvinyl alcohol (PVA) hydrogel crosslinked by cyclic freeze-thaw and reinforced by 3D-printed polycaprolactone (PCL) implants. The mechanical properties and surface morphologies of the artificial TMJ disc and the natural goat TMJ disc were tested and compared via compression, tensile, cyclic compression/tensile, creep, friction, scanning electron microscopy, and atomic force microscopy. The fibroblasts and chondrocytes were cultured on the artificial TMJ disc for 1, 3, and 5 d for cytotoxicity testing. Importantly, the artificial discs were placed into the TMJs of goats in an innovative way to induce disc defect repair for 12 wk. The PVA + PCL artificial disc demonstrated mechanical strength similar to that of natural disc, as well as 1) better fatigue resistance, viscoelasticity, and hydrophilicity; 2) less creep; and 3) low friction, cytotoxicity, and cell adhesion. By repairing the defects of the TMJ disc in goats, the artificial disc demonstrated the ability to maintain joint stability and protect condylar cartilage and bone from damage. These promising results indicate the feasibility of using a PVA + PCL artificial TMJ disc in a clinical context.

Rapid, Refined, and Robust Method for Expression, Purification, and Characterization of Recombinant Human Amyloid-beta M1-42

2019 ◽  
Author(s):  
Priya Prakash ◽  
Travis Lantz ◽  
Krupal P. Jethava ◽  
Gaurav Chopra
Keyword(s):  
Amyloid Beta ◽  
Western Blots ◽  
Force Microscopy ◽  
E Coli ◽  
Atomic Force ◽  
Set Up ◽  
Short Time

Amyloid plaques found in the brains of Alzheimer’s disease (AD) patients primarily consists of amyloid beta 1-42 (Ab42). Commercially, Ab42 is synthetized using peptide synthesizers. We describe a robust methodology for expression of recombinant human Ab(M1-42) in Rosetta(DE3)pLysS and BL21(DE3)pLysS competent E. coli with refined and rapid analytical purification techniques. The peptide is isolated and purified from the transformed cells using an optimized set-up for reverse-phase HPLC protocol, using commonly available C18 columns, yielding high amounts of peptide (~15-20 mg per 1 L culture) in a short time. The recombinant Ab(M1-42) forms characteristic aggregates similar to synthetic Ab42 aggregates as verified by western blots and atomic force microscopy to warrant future biological use. Our rapid, refined, and robust technique to purify human Ab(M1-42) can be used to synthesize chemical probes for several downstream in vitro and in vivo assays to facilitate AD research.

Targeting Breast Cancer Cells with G4 PAMAM Dendrimers and Valproic Acid Derivative Complexes

2020 ◽  
Vol 20 (15) ◽  
pp. 1857-1872
Author(s):  
Alberto M. Muñoz ◽  
Manuel J. Fragoso-Vázquez ◽  
Berenice P. Martel ◽  
Alma Chávez-Blanco ◽  
Alfonso Dueñas-González ◽  
...  
Keyword(s):  
Valproic Acid ◽  
Cell Lines ◽  
Water Solubility ◽  
Md Simulations ◽  
Pamam Dendrimer ◽  
Pamam Dendrimers ◽  
Force Microscopy ◽  
Micromolar Concentration ◽  
Atomic Force

Background: Our research group has developed some Valproic Acid (VPA) derivatives employed as anti-proliferative compounds targeting the HDAC8 enzyme. However, some of these compounds are poorly soluble in water. Objective: Employed the four generations of Polyamidoamine (G4 PAMAM) dendrimers as drug carriers of these compounds to increase their water solubility for further in vitro evaluation. Methods: VPA derivatives were subjected to Docking and Molecular Dynamics (MD) simulations to evaluate their affinity on G4 PAMAM. Then, HPLC-UV/VIS, 1H NMR, MALDI-TOF and atomic force microscopy were employed to establish the formation of the drug-G4 PAMAM complexes. Results: The docking results showed that the amide groups of VPA derivatives make polar interactions with G4 PAMAM, whereas MD simulations corroborated the stability of the complexes. HPLC UV/VIS experiments showed an increase in the drug water solubility which was found to be directly proportional to the amount of G4 PAMAM. 1H NMR showed a disappearance of the proton amine group signals, correlating with docking results. MALDI-TOF and atomic force microscopy suggested the drug-G4 PAMAM dendrimer complexes formation. Discussion: In vitro studies showed that G4 PAMAM has toxicity in the micromolar concentration in MDAMB- 231, MCF7, and 3T3-L1 cell lines. VPA CF-G4 PAMAM dendrimer complex showed anti-proliferative properties in the micromolar concentration in MCF-7 and 3T3-L1, and in the milimolar concentration in MDAMB- 231, whereas VPA MF-G4 PAMAM dendrimer complex didn’t show effects on the three cell lines employed. Conclusion: These results demonstrate that G4 PAMAM dendrimers are capableof transporting poorly watersoluble aryl-VPA derivate compounds to increase its cytotoxic activity against neoplastic cell lines.

Mechanical Interlocking on Leadframe Surface for Bondability of Au Wedge Bond

2016 ◽  
Vol 857 ◽  
pp. 79-82
Author(s):  
Roslina Ismail ◽  
Fuaida Harun ◽  
Azman Jalar ◽  
Shahrum Abdullah
Keyword(s):  
Optical Microscope ◽  
Bonding Process ◽  
Mechanical Interlocking ◽  
Average Roughness ◽  
Force Microscopy ◽  
Atomic Force ◽  
Surface Morphologies ◽  
Scanning Electron ◽  
Effect Of Surface

This work is a contribution towards the understanding of wire bond integrity and reliability in relation to their microstructural and mechanical properties in semiconductor packaging.The effect of surface roughness and hardness of leadframe on the bondability of Au wedge bond still requires detail analysis. Two type of leadframes namely leadframe A and leadframe B were chosen and scanning electron microscope (SEM) and optical microscope were used to inspect the surface morphology of leadframes and the quality of created Au wedge bond after wire bonding process. It was found that there were significant differences in the surface morphologies between these two leadframes. The atomic force microscopy (AFM) which was utilized to measure the average roughness, Ra of lead finger confirms that leadframe A has the highest Ra with value of 166.46 nm compared to that of leadframe B with value of 85.89 nm. While hardness value of different lead finger from the selected leadframe A and B obtained using Vicker microhardness tester are 180.9 VH and 154.2VH respectively.

scholarly journals Osteoblast-Like Cell Behavior on Porous Scaffolds Based on Poly(styrene) Fibers

2014 ◽  
Vol 2014 ◽  
pp. 1-6 ◽  
Author(s):  
Andrada Serafim ◽  
Romain Mallet ◽  
Florence Pascaretti-Grizon ◽  
Izabela-Cristina Stancu ◽  
Daniel Chappard
Keyword(s):  
Interference Microscopy ◽  
Porous Scaffolds ◽  
Allogenic Bone ◽  
Force Microscopy ◽  
Atomic Force ◽  
Dry Spinning ◽  
Bone Trabeculae ◽  
Large Bone

Scaffolds of nonresorbable biomaterials can represent an interesting alternative for replacing large bone defects in some particular clinical cases with massive bone loss. Poly(styrene) microfibers were prepared by a dry spinning method. They were partially melted to provide 3D porous scaffolds. The quality of the material was assessed by Raman spectroscopy. Surface roughness was determined by atomic force microscopy and vertical interference microscopy. Saos-2 osteoblast-like cells were seeded on the surface of the fibers and left to proliferate. Cell morphology, evaluated by scanning electron microscopy, revealed that they can spread and elongate on the rough microfiber surface. Porous 3D scaffolds made of nonresorbable poly(styrene) fibers are cytocompatible biomaterials mimicking allogenic bone trabeculae and allowing the growth and development of osteoblast-like cellsin vitro.

scholarly journals Atomic Force Microscopy Applied to Atopic Dermatitis Study

2021 ◽  
Vol 18 (4) ◽  
pp. 21-28
Author(s):  
Simona Maria Ţîrcă ◽  
Ion Ţîrcă ◽  
Marius Sorin Ciontea ◽  
Florin Dumitru Mihălţan
Keyword(s):  
Atomic Force Microscopy ◽  
Atopic Dermatitis ◽  
Structural Integrity ◽  
Clinical Investigation ◽  
Normal Skin ◽  
Skin Lesions ◽  
Force Microscopy ◽  
Atomic Force ◽  
Child Patient ◽  
Surface Morphologies

Abstract Atopic dermatitis (AD)-the commonest inflammatory skin disease affects up to 25% of children and 2% to 5% of adults. Methods of the diagnostic provide expanded recommendations founded on available evidence. Morphological evaluation remains a principal feature of clinical investigation and the main criteria of diagnosis. Methods. We collected normal and affected skin from a 6-month child patient who was diagnosed through dermatologic examination. Clinical characteristics and the diagnosis of atopic dermatitis were in accordance with Hanifin and Rajka criteria. Morphology and structural integrity were investigated by Atomic Force Microscopy. Results. Optical and topography images indicate that in the case of AD skin lesions the cuticle structure was severely damaged and distorted with the flattening and grading of the plates, which have an irregular appearance. From the surface morphologies of the samples, we demonstrate that the shape of the corneocytes, with granular and elongated appearance, specific to normal skin is transformed by AD into broken and collapsed plates with discontinuous appearance. Conclusions. In the initial diagnosis of AD changes of the skin properties can be an indicator. Hanifin and Rajka criteria together with Atomic Force Microscopy can be a useful and necessary technique diagnosing cases of atopic dermatitis.

scholarly journals Nanostructural and mechanical changes in the sclera following proteoglycan depletion

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.

scholarly journals Visualization by atomic force microscopy of tobacco mosaic virus movement protein–RNA complexes formed in vitro

2001 ◽  
Vol 82 (6) ◽  
pp. 1503-1508 ◽  
Author(s):  
O. I. Kiselyova ◽  
I. V. Yaminsky ◽  
E. M. Karger ◽  
O. Yu. Frolova ◽  
Y. L. Dorokhov ◽  
...  
Keyword(s):  
Atomic Force Microscopy ◽  
Tobacco Mosaic Virus ◽  
Mosaic Virus ◽  
Movement Protein ◽  
Structural Conversion ◽  
Force Microscopy ◽  
Rna Transcripts ◽  
Atomic Force ◽  
Rna Complexes

The structure of complexes formed in vitro by tobacco mosaic virus (TMV)-coded movement protein (MP) with TMV RNA and short (890 nt) synthetic RNA transcripts was visualized by atomic force microscopy on a mica surface. MP molecules were found to be distributed along the chain of RNA and the structure of MP–RNA complexes depended on the molar MP:RNA ratios at which the complexes were formed. A rise in the molar MP:TMV RNA ratio from 20:1 to 60–100:1 resulted in an increase in the density of the MP packaging on TMV RNA and structural conversion of complexes from RNase-sensitive ‘beads-on-a-string’ into a ‘thick string’ form that was partly resistant to RNase. The ‘thick string’-type RNase-resistant complexes were also produced by short synthetic RNA transcripts at different MP:RNA ratios. The ‘thick string’ complexes are suggested to represent clusters of MP molecules cooperatively bound to discrete regions of TMV RNA and separated by protein-free RNA segments.

scholarly journals Dynamic mechanisms of CRISPR interference by Escherichia coli CRISPR-Cas3

2021 ◽  
Author(s):  
Kazuto Yoshimi ◽  
Kohei TAKESHITA ◽  
Noriyuki Kodera ◽  
Satomi Shibumura ◽  
Yuko Yamauchi ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
High Speed ◽  
Dna Helicase ◽  
Type I ◽  
Loop Formation ◽  
Force Microscopy ◽  
Atomic Force ◽  
Target Strand ◽  
Target Dna

Type I CRISPR-Cas3 uses an RNA-guided multi Cas-protein complex, Cascade, which detects and degrades foreign nucleic acids via the helicase-nuclease Cas3 protein. Despite many studies using cryoEM and smFRET, the precise mechanism of Cas3-mediated cleavage and degradation of target DNA remains elusive. Here we reconstitute the CRISPR-Cas3 system in vitro to show how the Escherichia coli Cas3 (EcoCas3) with EcoCascade exhibits collateral non-specific ssDNA cleavage and target specific DNA degradation. Partial binding of EcoCascade to target DNA with tolerated mismatches within the spacer sequence, but not the PAM, elicits collateral ssDNA cleavage activity of recruited EcoCas3. Conversely, stable binding with complete R-loop formation drives EcoCas3 to nick the non-target strand (NTS) in the bound DNA. Helicase-dependent unwinding then combines with trans ssDNA cleavage of the target strand and repetitive cis cleavage of the NTS to degrade the target dsDNA substrate. High-speed atomic force microscopy demonstrates that EcoCas3 bound to EcoCascade repeatedly reels and releases the target DNA, followed by target fragmentation. Together, these results provide a revised model for collateral ssDNA cleavage and target dsDNA degradation by CRISPR-Cas3, furthering understanding of type I CRISPR priming and interference and informing future genome editing tools.

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