Neutralization kinetics of charged polymer surface

Crystallinity of semicrystalline polymers such as aliphatic homopolymer poly(L-lactic acid) (PLLA) affects their degradation and physical properties. In this paper, the effects of laser irradiation using the third harmonic of a Nd:YAG laser on the crystallinity, long-range order, and short-range conformations at the surface of PLLA films are investigated. The factors affecting the transformation are also studied. Detailed characterization of the effect of laser treatment is accomplished using microscopy, X-ray diffraction, and infrared spectroscopy. The cooling rates in the process and the spatial and temporal temperature profiles are numerically examined. The simulation results in conjunction with melting and crystallization kinetics of PLLA are used to understand the effect on sample crystallinity. The effects of laser fluence and annealing conditions on the crystallinity of the processed films are examined. Since degradation profiles depend on crystallinity, laser processing can potentially be used to achieve a modified spatially controlled polymer surface with promising applications such as controlled drug delivery.

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Controlled adhesion of human lymphocytes on electrically charged polymer surface having phosphorylcholine moiety

Science and Technology of Advanced Materials ◽

10.1016/s1468-6996(03)00014-7 ◽

2003 ◽

Vol 4 (2) ◽

pp. 99-104 ◽

Cited By ~ 9

Author(s):

Tomomi Ito ◽

Yasuhiko Iwasaki ◽

Tadashi Narita ◽

Kazunari >Akiyoshi ◽

Kazuhiko >Ishihara

Keyword(s):

Human Lymphocytes ◽

Polymer Surface ◽

Charged Polymer ◽

Electrically Charged

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Kinetics of charged polymer collapse: effects of additional salt

10.1101/2020.03.06.981431 ◽

2020 ◽

Author(s):

Susmita Ghosh ◽

Satyavani Vemparala

Keyword(s):

Charge Density ◽

Early Stage ◽

Finite Size ◽

Long Distance ◽

Charged Polymers ◽

Kinetics And Dynamics ◽

Polymer Models ◽

Charged Polymer ◽

Dynamics Simulations ◽

Kinetics Of

Extensive molecular dynamics simulations, using simple charged polymer models, have been employed to probe the kinetics and dynamics of early-stage collapse of charged polymers and the effect of additional monovalent salt on such kinetics. The exponents characterizing the coarsening dynamics during such early-collapse stage via finite size scaling for the case of charged polymers are found to be different from the neutral polymers, suggesting that the collapse kinetics of charged polymers are inherently different from that neutral polymers. The kinetics of coarsening of the clusters along the collapsed trajectory also depends significantly on the counterion valency and for higher valency counterions, multiple regimes are observed and unlike the neutral polymer case, the collapse kinetics are a function of charge density along the charged polymer. Inclusion of additional salt affects the kinetics and conformational landscape along the collapse trajectory. Addition of salt increases the value of critical charge density required to initiate collapse for all the counterion valencies, though the effect is more pronounced for monovalent counterion systems. The addition of salt significantly affects the collapse trajectory in the presence of trivalent counterions via promotion of transient long-distance loop structures inducing a parallel and hierarchical local collapsed conformation leading to faster global collapsed states. This may play a role in understanding the fast folding rates of biopolymers such as proteins and RNA from extended state to a collapsed state in the presence of multivalent counterions before reorganizing into a native fold.

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Kinetics of polymer-surface adsorption using viral coefficients

Macromolecules ◽

10.1021/ma00011a049 ◽

1991 ◽

Vol 24 (11) ◽

pp. 3361-3367 ◽

Cited By ~ 4

Author(s):

Douglas Poland

Keyword(s):

Polymer Surface ◽

Surface Adsorption ◽

Kinetics Of

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Effect Of Negatively-Charged Polyelectrolytes On Plasma Contact Factors And Factor V

10.1055/s-0038-1652888 ◽

1981 ◽

Author(s):

M C Boffa ◽

J P Faroes ◽

B P Dreyer ◽

C Pusineri

Keyword(s):

Protein C ◽

Human Factor ◽

Polymer Surface ◽

Factor Xii ◽

Factor V ◽

Surface Plasma ◽

Procoagulant Effect ◽

Charged Polymer ◽

Recalcification Time ◽

Similar Decrease

The action on plasma clotting of negatively-charged amphipathic polyelectrolytes, derived from copolymerisation of acrylonitrile, was investigated. These polymers were powdered suspended in citrated platelet-poor plasma at different polymer surface/plasma volume ratios. After centrifugation, the plasma supernatant was analyzed.Two opposite effects were observed: an immediate procoagulant effect and a progressive inhibitory one .The first was related to the activation of contact factors. Kinin-forming activity of kininogen as well as prekallicrein activity (measured on chromogenic substrate) were decreased: the former to a greater extent than the latter. However, no significant modification of factor XI and factor XII activities and no decrease of factor XII and HMW Kininogen level (according to immunological criteria) could be evidenced. On the other hand, when the incubation period was prolonged beyond 10 minutes, a progressive lengthening of the recalcification time was observed. This seemed to be due to the concomittant decrease of factor V activity (up to 90 %). In contrast, only a minimal decrease was observed with the same non-charged polymer. This effect was independent of protein C activation, since a similar decrease was also demonstrated after incubating purified human factor V with the negatively-charged polymer.In conclusion, contact factors are not the only ones modified by negative charges; in fact, factor V is particularly sensitive to these polyanions. Consequently, the observed final overall effect is delayed clotting.

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