scholarly journals Influence of surface charge on the formulation of elongated PEG-b-PDLLA nanoparticles

2020 ◽  
Vol 11 (16) ◽  
pp. 2775-2780 ◽  
Author(s):  
Roxane Ridolfo ◽  
David S. Williams ◽  
Jan C. M. van Hest
Keyword(s):  
Carboxylic Acid ◽  
Surface Charge ◽  
Shape Change ◽  
Fine Tuning

Amphiphilic PEG-PDLLA copolymers undergo assembly into polymersomes and can be transformed into tubular shapes using dialysis. By fine-tuning the shape change conditions also amine- and carboxylic acid modified polymersomes can now be effectively turned into tubes.

scholarly journals FGFR/Heartless and Smog interact synergistically to negatively regulate Fog mediated GPCR signaling

2019 ◽  
Author(s):  
Kumari Shweta ◽  
Anagha Basargekar ◽  
Anuradha Ratnaparkhi
Keyword(s):  
G Protein ◽  
Cell Shape ◽  
Shape Change ◽  
Control Cell ◽  
Negative Regulator ◽  
Fine Tuning ◽  
Dependent Manner ◽  
Gpcr Signaling ◽  
Cell Shape Change ◽  
Embryonic Cns

AbstractG-protein coupled receptor (GPCR) signaling triggered by Folded gastrulation (Fog) is one of the pathways known to regulate glial organization and morphogenesis in the embryonic CNS in Drosophila. Fog is best known for its role in epithelial morphogenesis during gastrulation. Here, the signaling pathway includes GPCRs Mist and Smog and the G-Protein Concertina (Cta) which activate downstream effectors to bring about cytoskeletal changes essential for cell shape changeIn this study, we identify molecular players that mediate and serve as important regulators of Fog signaling in the embryonic CNS. We find that while Cta is essential for Fog signaling neither receptors, Mist nor Smog mediates signaling in the CNS. On the contrary, we find that Smog functions as a negative regulator of the pathway. Surprisingly, Heartless which encodes a fibroblast growth factor receptor, also functions as a negative regulator of Fog signaling. Further, we find that both heartless and smog interact in a synergistic manner to regulate Fog signaling.This study thus identifies novel regulators of Fog signaling that may play an important role in fine-tuning the pathway to control cell morphogenesis. It also suggests the likelihood of there being multiple receptors for Fog that mediate and regulate signaling in a context specific manner.Author SummaryIn Drosophila, Folded gastrulation (Fog) functions as ligand that signals via GPCRs to regulate cell shape during gastrulation -one of the earliest events in embryogenesis. Here, Fog signals via receptors Mist and Smog to activate the G-protein Concertina to elicit change in cell shape. In the embryonic central nervous system (CNS) this pathway regulates shape and organization of glia important for functions such as insulation of neurons and synapses.The mechanism of Fog signal transduction in the CNS and its regulation is not well understood. We have sought to address these questions in our study. We find that Concertina is an essential factor for Fog signaling in the CNS but interestingly Mist is not. In contrast, Smog functions as a negative regulator such that loss of Smog enhances Fog signaling. A similar role is played by the receptor tyrosine kinase-Heartless. Interestingly, we find that Smog and Heartless interact as part of a common genetic network to regulate Fog signaling. Our results thus provide novel insights into the regulation of Fog signaling and shed light on how signaling can be fine-tuned in a context dependent manner to control cell shape change which plays a critical role during development and organ formation.

Relationship of the Discocyte—Echinocyte Shape Transformation to Red Cell Surface Charge

1975 ◽  
Vol 33 ◽  
pp. 512-513
Author(s):  
Y. Marikovskyand ◽  
C.S. Brown ◽  
H.H. Wortis
Keyword(s):  
Cell Surface ◽  
Surface Charge ◽  
Shape Change ◽  
Glucose Deprivation ◽  
Significant Loss ◽  
Atp Depletion ◽  
Shape Transformation ◽  
Survival Studies ◽  
Relationship Of ◽  
Human Rbcs

ATP-depletion of red blood cells (RBCs) by glucose deprivation transforms RBCs from the normal discocyte configuration into echinocytes. In the course of this shape change, there is a significant loss of membrane sialic acid, a decrease in cell surface negativity, and survival studies show that RBCs have an abbreviated life span. It is not known if the loss of negativity and decreased survival are directly related to nucleotide depletion or if they may be an inevitable consequence of the discocyte-echinocyte shape transformation.In the current study, we examined the effects of rapid discocyte-echinocyte transformations on RBC surface charge, as measured by cationized ferritin binding and agglutination rates in the presence of poly-L-lysine. Lysolecithin (LYL) is a strongly echinocytogenic lipid that transforms human RBCs into echinocytes in > 5 minutes, in contrast to ATP depletion by the method of Weed et al, which requires many hours to accomplish the same transformation.

Cytotoxicity of the Functionalized Gold and Silver Nanorods

2006 ◽  
Vol 951 ◽  
Author(s):  
Chiung-Wen Kuo ◽  
Jun-Jung Lai Lai ◽  
Peilin Chen
Keyword(s):  
Cell Death ◽  
Carboxylic Acid ◽  
Surface Charge ◽  
Cell Lines ◽  
Surface Functionalization ◽  
Silver Nanorods ◽  
Mtt Assays ◽  
Positively Charged ◽  
End Group

ABSTRACTThe cytotoxicity of various surface functionalized gold and silver nanords was measured by MTT assays for two cell lines, fibroblast and HeLa. It was found that the functionalized nanorods with 200 nm diameter and length up to a few micrometer can be readily internalized by both types of cells regardless of the surface functionalization. However, the cytotoxicity of the nanorods was found to depend on the polarity of the surface charge. The positively charged amino end group on the nanorod surface was found to be the least toxic whereas the negatively charged carboxylic acid end group on the nanorod surface caused lots of cell death. In general, the functionalized nanorods were found to be more toxic than the serum coated nanorods.

scholarly journals Magnetoelectric Membrane Filters of Poly(vinylidene fluoride)/Cobalt Ferrite Oxide for Effective Capturing of Particulate Matter

Polymers ◽  
2020 ◽  
Vol 12 (11) ◽  
pp. 2601
Author(s):  
Kyujin Ko ◽  
Su-Chul Yang
Keyword(s):  
Magnetic Field ◽  
Particulate Matter ◽  
Surface Charge ◽  
Vinylidene Fluoride ◽  
Shape Change ◽  
Membrane Surface ◽  
Public Health Issue ◽  
Membrane Filters ◽  
Phase Alignment ◽  
Poly Vinylidene Fluoride

In the last decade, particulate matter (PM) has gradually become a serious public health issue due to its harmful impact on the human body. In this study, we report a novel filtration system for high PM capturing, based on the magnetoelectric (ME) effect that induces an effective surface charge in membrane filters. To elucidate the ME effect on PM capturing, we prepared electrospun poly(vinylidene fluoride)(PVDF)/CoFe2O4(CFO) membranes and investigated their PM capturing efficiency. After electrical poling under a high electric field of 10 kV/mm, PM-capturing efficiencies of the poled-PVDF/CFO membrane filters were improved with carbon/fluorine(C/F) molar ratios of C/F = 4.81 under Hdc = 0 and C/F = 7.01 under Hdc = 700 Oe, respectively. The result illustrates that electrical poling and a dc magnetic field could, respectively, enhance the surface charge of the membrane filters through (i) a strong beta-phase alignment in PVDF (poling effect) and (ii) an efficient shape change of PVDF/CFO membranes (magnetostriction effect). The diffusion rate of a water droplet on the PVDF/CFO membrane surface is reduced from 0.23 to 0.05 cm2/s by covering the membrane surface with PM. Consequently, the PM capturing efficiency is dramatically improved up to 175% from ME membranes with the poling process and applying a magnetic field. Furthermore, the PM was successfully captured on the prototype real mask derived from the magnetoelectric effect induced by a permanent magnet with a diameter of 2 cm without any external power.

Electrochemical Impedance Study of GaAs Surface Charge Modulation through the Deprotonation of Carboxylic Acid Monolayers

Langmuir ◽  
2011 ◽  
Vol 27 (18) ◽  
pp. 11273-11277 ◽  
Author(s):  
Fernanda Camacho-Alanis ◽  
Homero Castaneda ◽  
Giovanni Zangari ◽  
Nathan S. Swami
Keyword(s):  
Carboxylic Acid ◽  
Surface Charge ◽  
Electrochemical Impedance ◽  
Gaas Surface ◽  
Impedance Study ◽  
Charge Modulation

Surface charge fine tuning of reversed-phase/weak anion-exchange type mixed-mode stationary phases for milder elution conditions

2015 ◽  
Vol 1409 ◽  
pp. 189-200 ◽  
Author(s):  
Aleksandra Zimmermann ◽  
Jeannie Horak ◽  
Orlando L. Sánchez-Muñoz ◽  
Michael Lämmerhofer
Keyword(s):  
Surface Charge ◽  
Anion Exchange ◽  
Mixed Mode ◽  
Stationary Phases ◽  
Reversed Phase ◽  
Fine Tuning

scholarly journals A seed flying like a bullet: ballistic seed dispersal in Chinese witch-hazel ( Hamamelis mollis OLIV., Hamamelidaceae)

2019 ◽  
Vol 16 (157) ◽  
pp. 20190327 ◽  
Author(s):  
Simon Poppinga ◽  
Anne-Sophie Böse ◽  
Robin Seidel ◽  
Linnea Hesse ◽  
Jochen Leupold ◽  
...  
Keyword(s):  
Shape Change ◽  
Rotational Velocity ◽  
Three Dimensional ◽  
Apical Part ◽  
Middle Part ◽  
Fine Tuning ◽  
Mechanical Pressure ◽  
Witch Hazel ◽  
Rotation Direction ◽  
Morphological Differences

The fruits of Chinese witch-hazel ( Hamamelis mollis , Hamamelidaceae) act as ‘drying squeeze catapults', shooting their seeds several metres away. During desiccation, the exocarp shrinks and splits open, and subsequent endocarp deformation is a complex three-dimensional shape change, including formation of dehiscence lines, opening of the apical part and formation of a constriction at the middle part. Owing to the constriction forming, mechanical pressure is increasingly applied on the seed until ejection. We describe a structural latch system consisting of connective cellular structures between endocarp and seed, which break with a distinct cracking sound upon ejection. A maximum seed velocity of 12.3 m s −1 , maximum launch acceleration of 19 853 m s −2 (approx. 2000 g ) and maximum seed rotational velocity of 25 714 min −1 were measured. We argue that miniscule morphological differences between the inner endocarp surface and seed, which features a notable ridge, are responsible for putting spin on the seed. This hypothesis is further corroborated by the observation that there is no preferential seed rotation direction among fruits. Our findings show that H. mollis has evolved similar mechanisms for stabilizing a ‘shot out’ seed as humans use for stabilizing rifle bullets and are discussed in an ecological (dispersal biology), biomechanical (seed ballistics) and functional–morphological (fine-tuning and morphospace of functional endocarps) contexts, and promising additional aspects for future studies are proposed.

Role of spectrin in membrane fusion and in shape change of human erythrocyte ghost

1978 ◽  
Vol 36 (2) ◽  
pp. 328-329
Author(s):  
Hideo Hayashi ◽  
Yoshikazu Hirai ◽  
John T. Penniston
Keyword(s):  
Conformational Changes ◽  
Human Erythrocyte ◽  
Shape Change ◽  
Membrane Surface ◽  
Slight Modification ◽  
Active Role ◽  
Main Role ◽  
Bank Blood ◽  
Human Erythrocyte Ghost

Spectrin is a membrane associated protein most of which properties have been tentatively elucidated. A main role of the protein has been assumed to give a supporting structure to inside of the membrane. As reported previously, however, the isolated spectrin molecule underwent self assemble to form such as fibrous, meshwork, dispersed or aggregated arrangements depending upon the buffer suspended and was suggested to play an active role in the membrane conformational changes. In this study, the role of spectrin and actin was examined in terms of the molecular arrangements on the erythrocyte membrane surface with correlation to the functional states of the ghosts.Human erythrocyte ghosts were prepared from either freshly drawn or stocked bank blood by the method of Dodge et al with a slight modification as described before. Anti-spectrin antibody was raised against rabbit by injection of purified spectrin and partially purified.

Imaging molecules adsorbed onto electrodes under potential control by scanning probe microscopy

1991 ◽  
Vol 49 ◽  
pp. 376-377 ◽  
Author(s):  
N.J. Tao ◽  
J.A. DeRose ◽  
P.I. Oden ◽  
S.M. Lindsay
Keyword(s):  
Surface Charge ◽  
Environmental Effects ◽  
Scanning Probe Microscopy ◽  
Statistical Significance ◽  
Electrochemical Methods ◽  
Surface Structures ◽  
Scanning Probe ◽  
Potential Control ◽  
Afm Imaging ◽  
Special Circumstances

Clemmer and Beebe have pointed out that surface structures on graphite substrates can be misinterpreted as biopolymer images in STM experiments. We have been using electrochemical methods to react DNA fragments onto gold electrodes for STM and AFM imaging. The adsorbates produced in this way are only homogeneous in special circumstances. Searching an inhomogeneous substrate for ‘desired’ images limits the value of the data. Here, we report on a reversible method for imaging adsorbates. The molecules can be lifted onto and off the substrate during imaging. This leaves no doubt about the validity or statistical significance of the images. Furthermore, environmental effects (such as changes in electrolyte or surface charge) can be investigated easily.

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