PROCEEDINGS OF THE 7 INTERNATIONAL ... - Fizika

MEDICAL PHYSICS IN THE BALTIC STATES 7 (2009)
Proceedings of the International Conference “Medical Physics 2009”
9 - 10 October 2009, Kaunas, Lithuania
NANODIAMONDS AS CELL BIOMARKERS
Augustinas KULBICKAS
Liquid Crystals Laboratory, Faculty of Physics and Technology, Vilnius Pedagogical University, Studentu 39,
LT-08106 Vilnius, Lithuania.
Email:augustinask@yahoo.com
Abstract: Optical microscopy and Raman spectroscopy of (N-V) defected nanodiamonds were performed at 300K and
77K. Molecules of 5CB LC demonstrating good anchoring with diamond surface and expose external defects of
diamonds. Internal (N-V) defects of diamonds possess fluorescence and spin manipulation at room temperature and
could be used as cell biomarkers.
Keywords: Nanodiamonds, (N-V) defects, Raman spectroscopy, fluorescence
1. Introduction
Diamond nanomaterials are good candidates for various
applications in physics, chemistry and biology. In the
biology one of the key avenues to understanding how
biological systems function at the molecular level is to
probe biomolecules individually and observe how they
interact with each other directly in vivo. Laser-induced
fluorescence is a technique widely adopted for this
purpose owing to its ultrahigh sensitivity and
capabilities of performing multiple-probe detection [1].
However, in applying this technique to imaging and
tracking a single molecule or particle in a biological
cell, progress is often hampered by the presence of
ubiquitous endogenous components such as flavins,
nicotinamide adenine dinucleotides, collagens and
porphyrins [2a,b,c,d, e] that produce high fluorescence
background signals These biomolecules typically absorb
light at wavelengths in the range of 300–500 nm and
fluoresce at 400–550 nm [3].To avoid such interference,
a good biological fluorescent probe should absorb light
at a wavelength longer than 500 nm and emit light at a
wavelength longer than 600 nm, at which the emission
has a long penetration depth through cells and tissues
Organic dyes and fluorescent proteins are two types of
molecules often used to meet such a requirement ;
however, the detrimental photo physical properties of
these molecules, such as photo bleaching and blinking,
inevitably restrict their applications for long-term in
vitro or in vivo observations. Fluorescent semiconductor
nanocrystals (or quantum dots), on the other hand, have
gained considerable attention in recent years because
they hold a number of advantageous features including
high photo bleaching thresholds and broad excitation
but narrow emission spectra well suited for multicolor
labelling and detection. Unfortunately, most
nanomaterials are toxic, and hence reduction of
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cytotoxicity and human toxicity through surface
modification plays a pivotal role in successful
application of quantum dots to in vivo labelling,
imaging, and diagnosis. Type Ib diamonds emit bright
fluorescence at 550–800 nm from nitrogen-vacancy
point defects, (N-V) 0 and (N-V) - , produced by highenergy
ion beam irradiation and subsequent thermal
annealing. The emission, together with non cytotoxicity
and easiness of surface functionalization, makes nanosized
diamonds a promising fluorescent probe for
single-particle tracking in heterogeneous environments
[1]. In particular, the designs of various biomarker
systems based on the Raman and fluorescent properties
of nanoparticles hold much promise, as opposed to
conventional organic fluorophores which suffer from
poor photo stability, narrow absorption spectra, and
broad emission features [4]. They unique optical
properties strongly depend on (N-V) defects in
diamond. Nitrogen-vacancy (N-V) defect are
responsible for the red/near-infrared fluorescence of
diamonds. Nanodiamonds with (N-V) centers can be
one of smallest cell markers being limited to the range
of tens of nanometers [1]. Now for diamond synthesis
are developed wide variety techniques: chemical vapor
deposition (CVD) [5], high pressure and high
temperature (HPHT) [6]. CVD technique is very
inefficient for creating N-V defects in nanodiamonds
[7]. Stable and bright fluorescent (N-V)-rich
nanodiamonds can be fabricated by irradiation and
annealing in vacuum of type Ib high pressure high
temperature (HPHT) diamonds grown from metal
catalysts in a few minutes [8].
In this manuscript are reporting structural, Raman and
fluorescence study of nanodiamonds properties to find
the possibility to use these nanodiamonds as cell
biomarkers.