Presentation is loading. Please wait.

Presentation is loading. Please wait.

Wroclaw University of Technology Electro-nanopores in the lipid membrane. Computer modeling vs experiments Malgorzata Kotulska Department of Biomedical.

Similar presentations


Presentation on theme: "Wroclaw University of Technology Electro-nanopores in the lipid membrane. Computer modeling vs experiments Malgorzata Kotulska Department of Biomedical."— Presentation transcript:

1 Wroclaw University of Technology Electro-nanopores in the lipid membrane. Computer modeling vs experiments Malgorzata Kotulska Department of Biomedical Engineering & Instrumentation Wroclaw University of Technology, Poland Kingston University, Dept. Computing, Information Systems and Mathematics

2 Wroclaw University of Technology Wroclaw

3 Wroclaw University of Technology

4 Membrane reorganization under electric field lipid bilayer with no porehydrophilic nanopore E ions molecules

5 Wroclaw University of Technology Cell electroporation Rapid-freezing electron microscopy of red blood cells before and after brief electric pulses (protoplasmic membrane face). Pore diameter 20-120 nm. DC. Chang and TS. Reese, Biophysical J. 58 (1990 ) Hypo-osmolar conditions – hemolysis (?) ML. Escande-Geraud et al., BBA 939 (1988) 247 Iso-osmolar  no effect GV. Gass, LV. Chernomordik, BBA 1023 (1990) 1

6 Wroclaw University of Technology Molecular Dynamics Lipid bilayer (2304 lipids) t k = 3680 ps. Red headgroups and blue chains; (yellow and green lipids - periodic images; water not shown) Movie from Tieleman DP., BMC Biochem. 2004, 19; 5:10.

7 Wroclaw University of Technology Energetical profile JC. Weaver and YA. Chizmandzhev, Bioelectrochem. Bioenerg. 41 (1996) 135 Free energy of the pore

8 Wroclaw University of Technology Problems Basic Mechanism of electroporation Shape of electropores (cylindrical or irregular ?) Applications Stabilizing of electropore (other than mechanical stress) Size control in long-lived electropores (e.g. big and stable electropores for DNA delivery) Control of the sensitivity to electroporation

9 Wroclaw University of Technology Monte Carlo simulations – modified Pink’s model The rate of heads in standing configuration show rapid head reorientation if E > 0.5 · 10 8 V/m (250 mV) H=H vdw + H conf + H dip + H e M. Kotulska, K. Kubica, Physical Review E 72 (2005) 061903 Kotulska M., Kubica K., Koronkiewicz S., Kalinowski S., Bioelectrochemistry 70 (2007) 64

10 Wroclaw University of Technology The rate of chains in gel (all-trans) and fluid conformations depends on electric field E if E > 0.5·10 8 V/m (250 mV) (NL – negative layer, PL – positive layer)

11 Wroclaw University of Technology Creation of a hydrophilic pore Kotulska M., Kubica K., in Advances in Planar Lipid Bilayers and Liposomes, vol. 7. ed. A. Leitmannova Liu, Elsevier, 2008

12 Wroclaw University of Technology Methods of electroporation Pulses Current clamp (M. Robello, A. Gliozzi BBA 982 (1989) 173)

13 Wroclaw University of Technology Electroporation under current-controlled conditions (chronopotentiometry - ChP) pore formation membrane charging pore fluctuations Voltage fluctuations under current-clamp, I = 0.2 nA, egg lecithin Kalinowski S., G. Ibron, K. Bryl, Z. Figaszewski. 1998., BBA 1369:204 ‑ 212

14 Wroclaw University of Technology Applications of chronopotentiometry M. Kotulska, S. Koronkiewicz, S. Kalinowski, Physical Review E 69 (2004), 031920 Noise 1/f, exponent dependent on physico-chemical conditions Modelling ischemic electroporated cell Kalinowski S, Koronkiewicz S, Kotulska M, Kubica K, Bioelectrochemistry 70 (2007) 83-90

15 Wroclaw University of Technology CACC electroporation (Chronoamperometry After Current Clamp) Electroporation at current clamp I Delay time; mean potential U m stabilized (at I) Clamping voltage at constant U m Data acquisition (at U m ) 1.5 M AlCl 3 (D AlCl3  1.3 nm) & 2 M NaCl (D NaCl  0.9 nm) M. Kotulska, Biophysical Journal 92 (2007), 2412-21

16 Wroclaw University of Technology Periodograms Periodograms for 2 M NaCl, B = 1.38, Sl =  0.6 nA2/Hz, Dmean = 1.73 nm (crosses, upper curve), 0.2 M NaCl, B = 1.37, Sl =  2.1 nA2/Hz, Dmean = 2.1 nm (diamonds, middle curve), and 1.5 M AlCl3, B = 1.55, Sl =  3.0 nA2/Hz, Dmean = 1.3 nm (squares, bottom curve).

17 Wroclaw University of Technology artificial nanopore / maltoporin channel Siwy Z, Fulinski A., Phys Rev Lett. 2002; 89(15):158101 Bezrukov SM, Winterhalter M. Phys Rev Lett. 2000; 85(1):202

18 Wroclaw University of Technology Models  Self-similar process or 1/f noise Hypotheses:  One long-term process  Sums of Markovian processes  Self-Organized Criticallity

19 Wroclaw University of Technology  -stable probability density function (MLE) (Left) Probability density function of the conductance dynamics approximated by MLE as a long ‑ tailed  -stable distribution (  = 1.78) and the smoothed data (stars). C onfidence interval 0.95 (Right) Tail region in log-log. Data obtained for 1.5 M AlCl 3 (B = 1.64, G = 2.4 nm) Statistical tests with STABLE program by JP. Nolan. (MLE, sample characteristic function and quantile methods,    [0.03, 0.1]) Kotulska M., Biophysical Journal 92 (2007), 2412-21

20 Wroclaw University of Technology Stability index  depends on the nanopore size. (Data for 2 M NaCl) fractional Levy stable motion tends to fractional Brownian motion

21 Wroclaw University of Technology Shape evolution (?) Images generated by Fractal Explorer

22 Wroclaw University of Technology Memory of the process Memory current-clamp < Memory CACC Feedback effect d = H  1/  (if d > 0 then the memory is long)

23 Wroclaw University of Technology Electroporation in medical applications

24 Wroclaw University of Technology Heart Defibrillation ELECTROCHEMOTHERAPY (ECT) ELECTROGENETHERAPY (EGT)

25 Wroclaw University of Technology Molecular transport into the cell Mir L.M, S. Orlowski, Adv.Drug Deliv. Rev. 35(1999) 107-118

26 Wroclaw University of Technology Electroporation in the cell Dev S.B. et al.. IEEE Trans. Plasma Sci. 28 (2000) 206-223

27 Wroclaw University of Technology ECT of a squamous cell carcinoma

28 Wroclaw University of Technology Mechanisms of anti-cancer effect  Enhanced transport of cytostatic drugs  Radiosensitizing effect of bleomycin  Vascular block

29 Wroclaw University of Technology Other pores/channels

30 Wroclaw University of Technology Modelling ionic flow through channels Enhanced algorithm for Poisson-Nernst-Planck model Nernst-Planck (Smoluchowski) Poisson Collaboration: Witek Dyrka, Andy Augousti

31 Wroclaw University of Technology Characteristics

32 Wroclaw University of Technology Optimization  Adaptive gradient-based optimisation of step size: super relaxation  Adjustable relaxation coefficient  Space segmentation

33 Wroclaw University of Technology Reducing computational cost Dyrka W., Augousti A.T., Kotulska M.: Ion flux through membrane channels – an enhanced algorithm for Poisson- Nernst-Planck model, submitted to J. Comp. Chemistry.

34 Wroclaw University of Technology Ryanodine receptor calcium channel Collaboration: Jean-Christophe Nebel FKBP12.6 RyR2

35 Wroclaw University of Technology SR Ca reuptake pump Na/Ca exchanger Efflux RyRs L-type channel Influx Ca Contrac t Ca Relax T-tubule myocyte sarcolemmal membrame M. Scoote, A.J. Williams, Cardiovascular Research 56 (2002) 359-372 Ca dependent electromechanical coupling in cardiac myocyte

36 Wroclaw University of Technology Diseases resulting from channelopathies 1. Malignant Hyperthermia (MH), 2. Central Core Disease (CDD) 3. Catecholaminergic Polymorphic Ventricular Tachycardia (CPVT). Hypotheses Mutations increase Ca2+ leak. Abnormal cardiac RyR phosphorylation and dissociation of FKBP12.6 may play a role in the pathogenesis of some forms of heart failure (HF), but this presumption needs more experimental support. Kania M. Kotulska M., A system for modeling the cooperativity of ryanodine receptors in cardiac myocytes, Proc. IFMBE 11 (2005) 1727-83,

37 Wroclaw University of Technology What is the pore structure? AJ. Williams, Q. Rev. Bioph. 34, 1 (2001), pp. 61–104. Y. Wang et al. Biophys. J. 89 (2005) 256-265

38 Wroclaw University of Technology Thank you for your attention


Download ppt "Wroclaw University of Technology Electro-nanopores in the lipid membrane. Computer modeling vs experiments Malgorzata Kotulska Department of Biomedical."

Similar presentations


Ads by Google