In vitro Performance of Nano-heterogeneous Dentin Adhesive

Water is ubiquitous in the mouths of healthy individuals and routinely interferes with efforts to bond restorations to dental tissues. Our previous studies using tapping-mode atomic force microscopy (TMAFM) have shown that nanophase separation is a general feature of cross-linked polymethacrylates photocured in the presence of water. To explore the relationship between nanophase separation in dentin adhesives and their long-term mechanical properties, we evaluated model adhesives after 3 months of aqueous storage. The degree of contrast in the TMAFM phase image depended on the formulations used, ranging from ‘not observable’ to ‘very strong’. Correspondingly, the mechanical properties of these model adhesives varied from ‘minimal change’ to ‘significant depreciation’. The results support the hypothesis that a high degree of heterogeneity at the nano-scale is associated with poor mechanical durability in these model adhesives.

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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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Mycobacterium tuberculosis and Paracoccidioides brasiliensis Formation and Treatment of Mixed Biofilm In Vitro

Frontiers in Cellular and Infection Microbiology ◽

10.3389/fcimb.2021.681131 ◽

2021 ◽

Vol 11 ◽

Author(s):

Kaila Petronila Medina-Alarcón ◽

Iara Pengo Tobias da Silva ◽

Giovana Garcia Ferin ◽

Marcelo A. Pereira-da-Silva ◽

Caroline Maria Marcos ◽

...

Keyword(s):

Mycobacterium Tuberculosis ◽

Paracoccidioides Brasiliensis ◽

Public Health Problem ◽

Extracellular Polysaccharide ◽

Force Microscopy ◽

Atomic Force ◽

High Degree ◽

First Time

Co-infection of Mycobacterium tuberculosis and Paracoccidioides brasiliensis, present in 20% in Latin America, is a public health problem due to a lack of adequate diagnosis. These microorganisms are capable of forming biofilms, mainly in immunocompromised patients, which can lead to death due to the lack of effective treatment for both diseases. The present research aims to show for the first time the formation of mixed biofilms of M. tuberculosis and P. brasiliensis (Pb18) in vitro, as well as to evaluate the action of 3’hydroxychalcone (3’chalc) -loaded nanoemulsion (NE) (NE3’chalc) against monospecies and mixed biofilms, the formation of mixed biofilms of M. tuberculosis H37Rv (ATCC 27294), 40Rv (clinical strains) and P. brasiliensis (Pb18) (ATCC 32069), and the first condition of formation (H37Rv +Pb18) and (40Rv + Pb18) and second condition of formation (Pb18 + H37Rv) with 45 days of total formation time under both conditions. The results of mixed biofilms (H37Rv + Pb18) and (40Rv + Pb18), showed an organized network of M. tuberculosis bacilli in which P. brasiliensis yeasts are connected with a highly extracellular polysaccharide matrix. The (Pb18 + H37Rv) showed a dense biofilm with an apparent predominance of P. brasiliensis and fragments of M. tuberculosis. PCR assays confirmed the presence of the microorganisms involved in this formation. The characterization of NE and NE3’chalc displayed sizes from 145.00 ± 1.05 and 151.25 ± 0.60, a polydispersity index (PDI) from 0.20± 0.01 to 0.16± 0.01, and zeta potential -58.20 ± 0.92 mV and -56.10 ± 0.71 mV, respectively. The atomic force microscopy (AFM) results showed lamellar structures characteristic of NE. The minimum inhibitory concentration (MIC) values of 3’hidroxychalcone (3’chalc) range from 0.97- 7.8 µg/mL and NE3’chalc from 0.24 - 3.9 µg/mL improved the antibacterial activity when compared with 3’chalc-free, no cytotoxicity. Antibiofilm assays proved the efficacy of 3’chalc-free incorporation in NE. These findings contribute to a greater understanding of the formation of M. tuberculosis and P. brasiliensis in the mixed biofilm. In addition, the findings present a new possible NE3’chalc treatment alternative for the mixed biofilms of these microorganisms, with a high degree of relevance due to the lack of other treatments for these comorbidities.

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Atomic force microscopy reveals the mechanical properties of breast cancer bone metastases

10.1101/2021.06.01.446539 ◽

2021 ◽

Author(s):

Xinyue Chen ◽

Russell Hughes ◽

Nic Mullin ◽

Rhoda J Hawkins ◽

Ingunn Holen ◽

...

Keyword(s):

Breast Cancer ◽

Mechanical Properties ◽

Atomic Force Microscopy ◽

Metastatic Cancer ◽

Metastatic Breast ◽

Metastatic Tumour ◽

Force Microscopy ◽

Atomic Force ◽

Cancer Metastases

Mechanically dependent processes are essential in cancer metastases. However, reliable mechanical characterisation of metastatic cancer remains challenging whilst maintaining the tissue complexity and an intact sample. Using atomic force microscopy, we quantified the micro-mechanical properties of relatively intact metastatic breast tumours and their surrounding bone microenvironment isolated from mice, and compared with other breast cancer models both ex vivo and in vitro. A unique mechanical distribution of extremely low elastic modulus and viscosity was identified on metastatic tumours, which were significantly more compliant than both 2D in vitro cultured cancer cells and subcutaneous tumour explants. The presence of mechanically distinct metastatic tumour did not result in alterations of the mechanical properties of the surrounding microenvironment at meso-scale distances (> 200 μm). These findings demonstrate the utility of atomic force microscopy in studies of complex tissues and provide new insights into the mechanical properties of cancer metastases in bone.

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

10.26434/chemrxiv.7725002.v1 ◽

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.

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

Anti-Cancer Agents in Medicinal Chemistry ◽

10.2174/1871520620666200423073812 ◽

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.

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Mechanical Properties of Membrane Surface of Cultured Astrocyte Revealed by Atomic Force Microscopy

Japanese Journal of Applied Physics ◽

10.1143/jjap.39.3711 ◽

2000 ◽

Vol 39 (Part 1, No. 6B) ◽

pp. 3711-3716 ◽

Cited By ~ 15

Author(s):

Hatsuki Shiga ◽

Yukako Yamane ◽

Etsuro Ito ◽

Kazuhiro Abe ◽

Kazushige Kawabata ◽

...

Keyword(s):

Mechanical Properties ◽

Atomic Force Microscopy ◽

Membrane Surface ◽

Force Microscopy ◽

Atomic Force

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Corrosion Behavior and Mechanical Properties of a Nanocomposite Superhydrophobic Coating

Coatings ◽

10.3390/coatings11060652 ◽

2021 ◽

Vol 11 (6) ◽

pp. 652

Author(s):

Divine Sebastian ◽

Chun-Wei Yao ◽

Lutfun Nipa ◽

Ian Lian ◽

Gary Twu

Keyword(s):

Electron Microscopy ◽

Mechanical Properties ◽

Scanning Electron Microscopy ◽

Atomic Force Microscopy ◽

Nanocomposite Coating ◽

Superhydrophobic Coating ◽

Force Microscopy ◽

Atomic Force ◽

Microscopy Images ◽

Scanning Electron

In this work, a mechanically durable anticorrosion superhydrophobic coating is developed using a nanocomposite coating solution composed of silica nanoparticles and epoxy resin. The nanocomposite coating developed was tested for its superhydrophobic behavior using goniometry; surface morphology using scanning electron microscopy and atomic force microscopy; elemental composition using energy dispersive X-ray spectroscopy; corrosion resistance using atomic force microscopy; and potentiodynamic polarization measurements. The nanocomposite coating possesses hierarchical micro/nanostructures, according to the scanning electron microscopy images, and the presence of such structures was further confirmed by the atomic force microscopy images. The developed nanocomposite coating was found to be highly superhydrophobic as well as corrosion resistant, according to the results from static contact angle measurement and potentiodynamic polarization measurement, respectively. The abrasion resistance and mechanical durability of the nanocomposite coating were studied by abrasion tests, and the mechanical properties such as reduced modulus and Berkovich hardness were evaluated with the aid of nanoindentation tests.

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The Infuence of Salicin on Rheological and Film-Forming Properties of Collagen

Molecules ◽

10.3390/molecules26061661 ◽

2021 ◽

Vol 26 (6) ◽

pp. 1661

Author(s):

Katarzyna Adamiak ◽

Katarzyna Lewandowska ◽

Alina Sionkowska

Keyword(s):

Mechanical Properties ◽

Atomic Force Microscopy ◽

Infrared Spectroscopy ◽

Rheological Properties ◽

Silver Carp ◽

Shear Tests ◽

Force Microscopy ◽

Atomic Force ◽

Film Forming ◽

Potential Applications

Collagen films are widely used as adhesives in medicine and cosmetology. However, its properties require modification. In this work, the influence of salicin on the properties of collagen solution and films was studied. Collagen was extracted from silver carp skin. The rheological properties of collagen solutions with and without salicin were characterized by steady shear tests. Thin collagen films were prepared by solvent evaporation. The structure of films was researched using infrared spectroscopy. The surface properties of films were investigated using Atomic Force Microscopy (AFM). Mechanical properties were measured as well. It was found that the addition of salicin modified the roughness of collagen films and their mechanical and rheological properties. The above-mentioned parameters are very important in potential applications of collagen films containing salicin.

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Extending AFM Phase Image of Nanocomposite Structures to 3D using FIB

MRS Proceedings ◽

10.1557/opl.2012.433 ◽

2012 ◽

Vol 1421 ◽

Cited By ~ 2

Author(s):

Russell J. Bailey ◽

Remco Geurts ◽

Debbie J. Stokes ◽

Frank de Jong ◽

Asa H. Barber

Keyword(s):

Phase Contrast ◽

Focused Ion Beam ◽

Ion Beam ◽

Polymer Nanocomposite ◽

Three Dimensions ◽

Phase Image ◽

Force Microscopy ◽

Atomic Force ◽

Mechanical Information ◽

Nanocomposite Structures

ABSTRACTThe mechanical behavior of nanocomposites is critically dependent on their structural composition. In this paper we use Focused Ion Beam (FIB) microscopy to prepare surfaces from a layered polymer nanocomposite for investigation using phase contrast atomic force microscopy (AFM). Phase contrast AFM provides mechanical information on the surface examined and, by combining with the sequential cross-sectioning of FIB, can extend the phase contract AFM into three dimensions.

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