Lomonosov Moscow State University
Physics Department
SPECIFIC INTERACTION OF ALBUMIN
MOLECULES IN WATER SOLUTION,
CONTAINING SILICON NANOPARTICLES
AT DIFFERENT NET CHARGE OF PROTEIN
Ksenia A. Anenkova, Galina P. Petrova,
Lubov A. Osminkina, Konstantin P. Tamarov.
Bovine Serum Albumin (BSA)
Molecular weight – 65 kDa
Mesoporous Silicon
nanoparticles
(MP-Si nanoparticles)
Owing to their biological compatibility
with living tissues and ability of fast
Characteristic sizes – 4*4*14 nm
removal from the organism, the silicon
Isoelectric point pH 4.9
nanoparticles
may
be
used
as
Albumin molecules realize transport
photosensitisers in photodynamic therapy
function
of cancer and as drug delivery systems.
and
maintenance
colloid-osmotic pressure in blood.
of
Experimental setup
Main parameters: laser’s wavelength 647nm, power P=25mW
Fundamental formula:
In case of a poly-dispersed solution :
Fig.1. Autocorrelation function of
scattered light
g(1)(t) is first order field correlation function, g(2)(t) is second order intensity
auto-correlation function, accumulated by correlator during the experiment
Fig.2. pH dependence of the scattering centers translation
diffusion coefficient in BSA water solution
According to Scatchar theory nonlinear character of dependence at fig.1 is described by
next formula
where B is the second virial coefficien in the expansion for free energy,
known as coefficient of intermolecular interaction
B=
V1
M 22
β 22
β 223 m3
Z2
+
−
4m3
2
4+ 2β33 m3
(
)
Dt =D0 {1+ (2BM− [η ])c }
Fig.3. pH dependence of the scattering centers translation diffusion
coefficient in mesoporous silicon nanoparticles water solution
Mesoporous silicon nanoparticles are hydrophilic. Due to this property a
water shell is formed around them. This leads to a partial shielding of particles
net charge. Therefore, the shape of dependence at fig.3 is more smooth.
Fig.4. pH dependence of the scattering centers translation diffusion
coefficient in mesoporous silicon nanoparticles + BSA water solution
Images of MP-Si nanoparticles, obtained by TEM
In water solution MP-Si nanoparticles
exist as clusters with sizes ranging from
100 nm to 1 mm.
Ultrasonic
treatment,
followed
by
filtration, allows us to select the desired
particles size.
136.42нм
Comparison of the results obtained
by dynamic light scattering with TEM
2
1
3
136.42нм
kT
R
6Dt
IR spectrometer Bruker IFS 66v/S
Technical
characteristics:
Scanning range:
7500 – 370 сm-1
Resolution: 0.25 сm-1
Evacuating the
measuring chamber to 3
mbar
IR spectroscopy is widely used to determine the composition of porous silicon layers.
Fig.5. IR transmission spectrum for Mp-Si nanoparticles
in the range from 800 to 2500 сm-1
• SiH3 antisymmetric deformation vibrations 877сm-1
• SiO stretching vibrations in Si-O-Si 1064сm-1
• SiH stretching vibrations in O3-SiH 2266сm-1
Fig.6. IR transmission spectrum for BSA in the range from 800 to 2000 сm-1
•Amide-I (С=O stretching vibrations ) 1650 cm-1
•Amide-II (CN stretching vibrations and NH deformational vibrations) 1520 cm-1
•COO- 1390 cm-1
•Amide-III (CN stretching vibrations and NH rotating) 1220-1330 cm-1
What are we looking for in the IR-spectrum
BSA+MP-Si nanoparticles?
We are looking for amide-I and amide-II bands frequencies shifts. This shifts detect
secondary structural changes caused by interaction of nanoparticles and protein.
The examples of such shifts for system BSA+ lead acetate are shown at fig.7 For this
system is well known that there is an interaction between BSA macromolecules and lead
acetate.
Fig.7. IR transmission spectra for BSA and BSA+lead acetate in the range
from 800 to 2000 сm-1
Fig.8. IR transmission spectrum for BSA+Mp-Si nanoparticles in the range
from 800 to 1800 сm-1
There is no any shifts of amide-I or amide-II bands in BSA+MP-Si nanoparticles system
compared to pure protein. So it means that there is no interaction in this system.
Hydrophilic properties of MP-Si nanoparticles can explain the absence of interaction
between the nanoparticles’ surface OH groups and CO groups of BSA
The absence of OH- CO groups interaction also can be explained by unsufficient for stable
bond amount of H on the surface of particles
Conclusions:
• The investigation of molecular parameters of serum albumin in water
solution by DLS method has shown that the addition of nanoparticles
does not
change the mobility of the scattering particles within the
experimental error.
• In the obtained IR spectra is not observed shift to short wave area,
characteristic for the formation of hydrogen bonds between the
carbonyl groups of the protein and the OH groups on the silicon
nanoparticles surface (shoulder 1650 for C = O stretching vibrations)
• Present results show that there is no interaction between albumin
molecules and silicon nanoparticles in the investigated systems.
Thank you for your attention!
If you have any questions, I will gladly answer them by e-mail
ksensanna@gmail.com