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Scientific Report 2007-2009
Laboratories and Facilities of the Department of Physics
L2. Cell Biophysics Lab
The Cell Biophysics Laboratory is engaged in the characterization of the electrical and structural properties of biological
objects of different complexity and different structural organization (nanoparticles, liposomes, micelles, biological cells,
biological tissues), by means of different experimental techniques. The laboratory is equipped with a broad-band Frequency
Domain Dielectric Spectroscopy set up (Hewlett-Packard Impedance Analyzers), covering the frequency range from 40 Hz
to 2 GHz, which allows measurements of the permittivity ϵ ′ (ω) and dielectric loss ϵ ” (ω) of biological suspensions in the
temperature interval from -10 to 60 ◦ C.
The technique spans over a wide range of characteristic
times, providing information on different
molecular mechanisms (Fig. 1).The size and size
distribution of the biological objects at a nanoand
mesoscopic scale is carried out by means of a
Dynamic Light Scattering apparatus (Brookhaven
FOQELS), measuring the decay of the intensityintensity
correlation functions in a temporal
interval from 0.1 µs to some tens of minutes. The
technique allows to follow the evolution of the
characteristic size during the aggregation processes
from simpler to more complex structures. The
surface electrical charge distribution is investigated
by means of the laser Doppler electrophoresis
technique using a MALVER Zetamaster apparatus
equipped with a 5 mW He-Ne laser.In biological
samples, electrophoresis is ultimately caused by
the presence of a charged interface between the
particle surface and the surrounding fluid, which
imparts the motion of dispersed particles relative
Figure 1: Broad-band dielectric spectroscopy opens unexpected potentiality
in the investigation of biological colloidal systems.
to a fluid. In order to prepare a monolayer of amphiphilic molecules on the surface of a liquid, the Laboratory is equipped
with a Langmuir-Blodgett [LB] trough, offering the possibilityto compress or expand these molecules on the surface, thereby
modifying the molecular density. The monolayers effect on the surface pressure of the liquid is measured through use of a
Wilhelmy plate. A LB film can then be transferred to a solid substrate by dipping the substrate through the monolayer.In
addition, films can be made of biological materials to improve cell adhesion or study the properties of biofilms.
Related research activities: C19.
L3. Bio Macromol Lab
The laboratory is used from about 30 years for researches devoted to characterize the physical properties of biopolymers
and to study processes of interactions with amphifile molecules, in condition of self-aggregation. Other research involves
studies on alterations in plasma membrane of cells, subjected to biochemical or physical stress.
The main techniques available in the Lab are as follows:
1)Dielectric set-up consisting in two HP Impedance Analyzers mod. 4194A and 4291A, that cover the frequency ranges 10
kHz - 100 MHz and 1MHz - 1.8 GHz respectively, equipped with thermostated dielectric cells.
2)Electrorotation set-up for measurements of specific capacitance and conductance of plasma membrane of cells.
3)Malvern Zeta Size Nano for measurements of Zeta Potential and Dynamic Light Scattering.
4)Luminescence Spectrometer Perkin Elmer LS50
Related research activities: C25.
Sapienza Università di Roma 177 Dipartimento di Fisica