Dielectric relaxation in Hyaluronic acid sodium salt

1
Dielectric relaxation in Hyaluronic acid sodium
salt

• S.Dolanski Babic1,2, T.Ivek1, T.Vuletic1,
• S.Tomic1 and R.Podgornik3,4
• 1Institut za fiziku, Zagreb, Hrvatska
• 2Zavod za fiziku i biofiziku, Medicinski
  fakultet, Zagreb, Hrvatska
• 3Department of Physics, University of Ljubljana,
  Ljubljana, Slovenia
• 4J.Stefan Institute, Ljubljana, Slovenia

2

• I Introduction
• II Samples
• III Low freq. Dielectric Spectroscopy
• IV Results
• V Plans

3

• Introduction

glucose

• - Hyaluronan (hyaluronic acid or hyaluronate) is
  simple polymer of disaccharides themselves
• - composed of glucuronic acid and
  N-acetylglucosamine
• - linked together via alternating glycosidic
  bonds
• - Molecular weight of one monomer is 400 Da

4

• Introduction

• HYALURONAN IS-
• - found in all tissues and body fluids of
  vertebrates as well as in some bacteria
• - synthesized in the cellular plasma membrane
• - a major component of the synovial fluid and was
  found to increase the viscosity of the fluid
• - a major constituent in the vitreous of the
  human eye
• an important component of articular cartilage,
  where it is present as a coat around each cell
• - is also a major component of skin, where it is
  involved in tissue repair

1 nm
Hyaluronan (HA) can be 25.000 monomers in length
5

• Samples

• Hyaluronic acid Sodium salt from Streptococcus
  equi sp. (BioChemika Fluka)
• - molecular weights of HA are in the range 300
  kDa- 1900 kDa
• - polydisperse HA fragments in the range 750-
  5000 monomers (0.75 -5 mm)
• - pure water solutions in the range of 0.01-5
  mg/mL
• - pure water MilliPore, Milli-Q, 0.056 mS/cm

K.Tamoto, Semin.Arthritis Rheum., Vol. 22 (1993)
6

• Dielectric spectroscopy (40 Hz-100 MHz)

Impedance analyzer Agilent 4294 measures
capacitance, C and conductance, G (real part)
Y(w) G(w)iwC(w)

• Chamber for liquid samples water solutions
• conductivity 1.5-2000 mS/cm
• drops vol. 50-200 mL
• reproducibility 0.8
• long term (2 h) 2

Temperature control unit Temp. range5C -
60C Stability0.1 K
Pt
7

• From complex conductance to complex dielectric
  function

Y(w)G(w)iwC(w)

• G(w) and C(w) of DNA solutions are measured
• - These are subtracted for (G, C) of
  background (reference) NaCl solution with
  matching conductivity (at 100kHz)

- This procedure enables to eliminate the
electrode polarization effects, as well as other
stray impedance effects.
8

• From complex conductance to complex dielectric
  function

(G-GNaCl, C-CNaCl)
e(w) e(w)-ie(w)
FITS to a sum of two generalized Debye functions

• - relaxation process strength, ??
• - ?0, central relaxation time
• - symmetric broadening of the relaxation time
  distribution, 1 - ?

9

• Results

• HA pure water solutions dielectric response
  spectra feature two modes
• (as DNA solutions)
• - two relaxation modes in kHz and MHz ranges

10

• Results

HF mode De ? 4, 1-a ? 0.82
LF mode De ? 60 for c lt 0.2 mg/mL De ? 10 for
c gt 0.4 mg/mL 1-a ? 0.75
tLF
tHF
11
Results
semidilute regime above c0.001 mg/mL
12

• Results

a0.5
a0.4
13

• Results

fHF - fraction of counterions participating in
the HF process aHF - polarizability
14

• Plans

• Repeat the dielectric spectroscopy for Hyaluronic
  acid pure water solutions in the same range of HA
  concentration as reported here.
• 2. Hyaluronic acid in NaCl electrolyte (with
  added salt of fixed or varying concentration),
  similar range of HA concentration as reported
  here.