The Influence of the Operating Parameters of Titanium Electropolishing to Obtain Nanostructured Titanium Surfaces

2012 ◽  
Vol 727-728 ◽  
pp. 1638-1642
Author(s):  
Leonardo Marasca Antonini ◽  
Rafael Gomes Mielczarski ◽  
Caroline Pigatto ◽  
Iduvirges Lourdes Müller ◽  
Célia de Fraga Malfatti
Keyword(s):  
Operating Parameters ◽  
Nanostructured Titanium ◽  
Nanostructured Surfaces ◽  
Force Microscopy ◽  
Angle Measurements ◽  
Atomic Force ◽  
Different Temperatures ◽  
Titanium Surfaces

Titanium and Ti alloys have been widely used as biomaterial due to their mechanical properties and high in vitro and in vivo cytocompatibility. Studies have showed that the acceleration of the osseointegration process is associated to the modification of the surface morphology. The aim of this work is to study the influence of the operating parameters of titanium electropolishing to obtain nanostructured titanium surfaces. The titanium electropolishing was carried out with different temperatures (7°C, 18°C and 25°C), current density of 0.19 A/cm2 and electropolishing time of 8 minutes. After the electropolishing process the titanium samples were characterized by Atomic Force Microscopy, profilometry (mechanical profilometer) and contact angle measurements. Preliminary results showed that the Ti nanostructured surfaces formation, strongly depends on the control of operating parameters.

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.

scholarly journals Ultrafiltration Segregates Tissue Regenerative Stimuli Harboured Within and Independent of Extracellular Vesicles

2020 ◽  
Author(s):  
TT Cooper ◽  
SE Sherman ◽  
T Dayarathna ◽  
GI Bell ◽  
Jun Ma ◽  
...  
Keyword(s):  
Extracellular Vesicles ◽  
Limb Ischemia ◽  
Murine Models ◽  
Label Free ◽  
Tubule Formation ◽  
Simple Method ◽  
Force Microscopy ◽  
Atomic Force

AbstractThe release of extracellular vesicles (EVs) from human multipotent stromal cells (MSC) has been proposed as a mechanism by which MSC mediate regenerative functions in vivo. Our recent work has characterized MSC derived from human pancreatic tissues (Panc-MSC) that generated a tissue regenerative secretome. Despite these advancements, it remains unknown whether regenerative stimuli are released independent or within extracellular vesicles. Herein, this study demonstrates ultrafiltration is a simple method to enrich for EVs which can be injected in murine models of tissue regeneration. The enrichment of EVs from Panc-MSC conditioned media (CM) was validated using nanoscale flow cytometry and atomic force microscopy; in addition to the exclusive detection of classical EV-markers CD9, CD81, CD63 using label-free mass spectrometry. Additionally, we identified several pro-regenerative stimuli, such as WNT5A or ANGPT1, exclusive to EV-enriched CM. Endothelial cell tubule formation was enhanced in response to both Panc-MSC CM fractions in vitro yet only intramuscular injection of EV-enriched CM demonstrated vascular regenerative functions in NOD/SCID mice with unilateral hind-limb ischemia (*<p<0.05). Furthermore, both EV-depleted and EV-enriched CM reduced hyperglycemia following intrapancreatic injection in hyperglycemic mice (**p<0.01). Collectively, understanding the functional synergy between compartments of the secretome is required to advance cell-free biotherapeutics into applications of regenerative medicine.

scholarly journals Nanosized Particles Assembled by a Recombinant Virus Protein Are Able to Encapsulate Negatively Charged Molecules and Structured RNA

Polymers ◽  
2021 ◽  
Vol 13 (6) ◽  
pp. 858
Author(s):  
Hemalatha Mani ◽  
Yi-Cheng Chen ◽  
Yen-Kai Chen ◽  
Wei-Lin Liu ◽  
Shih-Yen Lo ◽  
...  
Keyword(s):  
Self Assembly ◽  
Rna Binding ◽  
Core Protein ◽  
Average Diameter ◽  
Virus Protein ◽  
Force Microscopy ◽  
Atomic Force ◽  
Hcv Core Protein

RNA-based molecules have recently become hot candidates to be developed into therapeutic agents. However, successful applications of RNA-based therapeutics might require suitable carriers to protect the RNA from enzymatic degradation by ubiquitous RNases in vivo. Because of their better biocompatibility and biodegradability, protein-based nanoparticles are considered to be alternatives to their synthetic polymer-based counterparts for drug delivery. Hepatitis C virus (HCV) core protein has been suggested to be able to self-assemble into nucleocapsid-like particles in vitro. In this study, the genomic RNA-binding domain of HCV core protein consisting of 116 amino acids (p116) was overexpressed with E. coli for investigation. The recombinant p116 was able to assemble into particles with an average diameter of approximately 27 nm, as visualized by electron microscopy and atomic force microscopy. Measurements with fluorescence spectroscopy, flow cytometry, and fluorescence quenching indicated that the p116-assembled nanoparticles were able to encapsulate small anionic molecules and structured RNA. This study demonstrates methods that exploit the self-assembly nature of a virus-derived protein for nanoparticle production. This study also suggests that the virus-derived protein-assembled particles could possibly be developed into potential carriers for anionic molecular drugs and structured RNA-based therapeutics.

scholarly journals Directed Irradiation Synthesis as an Advanced Plasma Technology for Surface Modification to Activate Porous and “as-received” Titanium Surfaces

Metals ◽  
2019 ◽  
Vol 9 (12) ◽  
pp. 1349 ◽  
Author(s):  
Ana Civantos ◽  
Jean Paul Allain ◽  
Juan Jose Pavón ◽  
Akshath Shetty ◽  
Osman El-Atwani ◽  
...  
Keyword(s):  
Contact Angle ◽  
Surface Modification ◽  
Titanium Implants ◽  
Lower Percentage ◽  
Force Microscopy ◽  
Atomic Force ◽  
Titanium Surfaces ◽  
Singly Charged ◽  
Biological Performance

For the design of smart titanium implants, it is essential to balance the surface properties without any detrimental effect on the bulk properties of the material. Therefore, in this study, an irradiation-driven surface modification called directed irradiation synthesis (DIS) has been developed to nanopattern porous and “as-received” c.p. Ti surfaces with the aim of improving cellular viability. Nanofeatures were developed using singly-charged argon ions at 0.5 and 1.0 keV energies, incident angles from 0° to 75° degrees, and fluences up to 5.0 × 1017 cm−2. Irradiated surfaces were evaluated by scanning electron microscopy, atomic force microscopy and contact angle, observing an increased hydrophilicity (a contact angle reduction of 73.4% and 49.3%) and a higher roughness on both surfaces except for higher incident angles, which showed the smoothest surface. In-vitro studies demonstrated the biocompatibility of directed irradiation synthesis (DIS) reaching 84% and 87% cell viability levels at 1 and 7 days respectively, and a lower percentage of damaged DNA in tail compared to the control c.p. Ti. All these results confirm the potential of the DIS technique to modify complex surfaces at the nanoscale level promoting their biological performance.

Fibronectin modified TiO2 nanotubes modulate endothelial cell behavior

2018 ◽  
Vol 33 (1) ◽  
pp. 44-51 ◽  
Author(s):  
Ziyang Jin ◽  
Xufeng Yan ◽  
Guiyong Liu ◽  
Min Lai
Keyword(s):  
Photoelectron Spectroscopy ◽  
Umbilical Vein ◽  
Cell Counting ◽  
Cellular Functions ◽  
Force Microscopy ◽  
Angle Measurements ◽  
Atomic Force ◽  
Substrate Surfaces ◽  
Umbilical Vein Endothelial Cells

Cardiovascular disease has become a great threat to the health of mankind; current titanium (Ti) stents fail due to late stent thrombosis caused by the lack of re-endothelialization of the Ti stent. The objective of this study was to design a novel cardiovascular Ti implant with improved surface biocompatibility. TiO2 nanotubes with a diameter of 110 nm were anodized at a constant voltage of 30 V, and fibronectin was immobilized onto the TiO2 nanotubes using polydopamine. The element composition, morphology, and wettability of the different substrate surfaces were characterized by x-ray photoelectron spectroscopy (XPS), field-emission scanning electron microscopy (FE-SEM), atomic force microscopy (AFM), and contact angle measurements, respectively, confirming the successful immobilization of fibronectin. In vitro experiments including immunofluorescence staining, Cell Counting Kit-8 (CCK-8), and nitric oxide (NO) and prostacyclin (PGI2) release demonstrate that fibronectin modified TiO2 nanotubes supported cell adhesion, proliferation, and normal cellular functions of human umbilical vein endothelial cells (HUVECs). These methodologies can be applied for future fabrication of cardiovascular stents.

scholarly journals Computational model for nanocarrier binding to endothelium validated using in vivo, in vitro, and atomic force microscopy experiments

2010 ◽  
Vol 107 (38) ◽  
pp. 16530-16535 ◽  
Author(s):  
J. Liu ◽  
G. E. R. Weller ◽  
B. Zern ◽  
P. S. Ayyaswamy ◽  
D. M. Eckmann ◽  
...  
Keyword(s):  
Atomic Force Microscopy ◽  
Computational Model ◽  
Force Microscopy ◽  
Atomic Force

scholarly journals Analysis of long dsRNA produced in vitro and in vivo using atomic force microscopy in conjunction with ion-pair reverse-phase HPLC

The Analyst ◽  
2019 ◽  
Vol 144 (16) ◽  
pp. 4985-4994
Author(s):  
Alison O. Nwokeoji ◽  
Sandip Kumar ◽  
Peter M. Kilby ◽  
David E. Portwood ◽  
Jamie K. Hobbs ◽  
...  
Keyword(s):  
Atomic Force Microscopy ◽  
High Performance ◽  
Ion Pair ◽  
Reverse Phase Hplc ◽  
Reverse Phase ◽  
Force Microscopy ◽  
Atomic Force ◽  
Insight Into

Atomic force microscopy (AFM) in conjunction with ion-pair reverse-phase high performance liquid chromatography (IP-RP-HPLC) provides novel insight into dsRNA for RNAi applications.

scholarly journals Exploring the action of RGDV-gemcitabine on tumor metastasis, tumor growth and possible action pathway

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Xiaoyi Zhang ◽  
Jinhuan Zhang ◽  
Wenchao Liu ◽  
Yaonan Wang ◽  
Jianhui Wu ◽  
...  
Keyword(s):  
Tumor Metastasis ◽  
A549 Cells ◽  
Force Microscopy ◽  
Atomic Force ◽  
Tnf Α ◽  
First Time ◽  
Inhibit Tumor Metastasis ◽  
Necrosis Factor

Abstract The coupling of Arg-Gly-Asp-Val (RGDV) and gemcitabine led to a hypothesis that the conjugate (RGDV-gemcitabine) could inhibit tumor metastasis. To confirm this hypothesis the activities of RGDV-gemcitabine inhibiting tumor metastasis in vitro and in vivo were presented for the first time. AFM (atomic force microscopy) imaged that RGDV-gemcitabine was able to adhere onto the surface of serum-starved A549 cells, to block the extending of the pseudopodia. Thereby RGDV-gemcitabine was able to inhibit the invasion, migration and adhesion of serum-starved A549 cells in vitro. On C57BL/6 mouse model RGDV-gemcitabine dose dependently inhibited the metastasis of planted tumor towards the lung and the minimal dose was 0.084 µmol/kg/3 days. The decrease of serum TNF-α (tumor necrosis factor), IL-8 (interleukin-8), MMP-2 (matrix metalloprotein-2) and MMP-9 (matrix metalloprotein-9) of the treated C57BL/6 mice was correlated with the action pathway of RGDV-gemcitabine inhibiting the metastasis of the planted tumor towards lung.

scholarly journals β-Arrestin2 oligomers impair the clearance of pathological tau and increase tau aggregates

2020 ◽  
Vol 117 (9) ◽  
pp. 5006-5015 ◽  
Author(s):  
Jung-A A. Woo ◽  
Tian Liu ◽  
Cenxiao C. Fang ◽  
Maria A. Castaño ◽  
Teresa Kee ◽  
...  
Keyword(s):  
Tau Pathology ◽  
Force Microscopy ◽  
Genetic Ablation ◽  
Feedback Cycle ◽  
Atomic Force ◽  
New Strategy ◽  
Tau Aggregation ◽  
G Protein Coupled

Multiple G protein-coupled receptors (GPCRs) are targets in the treatment of dementia, and the arrestins are common to their signaling. β-Arrestin2 was significantly increased in brains of patients with frontotemporal lobar degeneration (FTLD-tau), a disease second to Alzheimer’s as a cause of dementia. Genetic loss and overexpression experiments using genetically encoded reporters and defined mutant constructs in vitro, and in cell lines, primary neurons, and tau P301S mice crossed with β-arrestin2−/−mice, show that β-arrestin2 stabilizes pathogenic tau and promotes tau aggregation. Cell and mouse models of FTLD showed this to be maladaptive, fueling a positive feedback cycle of enhanced neuronal tau via non-GPCR mechanisms. Genetic ablation of β-arrestin2 markedly ablates tau pathology and rescues synaptic plasticity defects in tau P301S transgenic mice. Atomic force microscopy and cellular studies revealed that oligomerized, but not monomeric, β-arrestin2 increases tau by inhibiting self-interaction of the autophagy cargo receptor p62/SQSTM1, impeding p62 autophagy flux. Hence, reduction of oligomerized β-arrestin2 with virus encoding β-arrestin2 mutants acting as dominant-negatives markedly reduces tau-laden neurofibrillary tangles in FTLD mice in vivo. Reducing β-arrestin2 oligomeric status represents a new strategy to alleviate tau pathology in FTLD and related tauopathies.

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