Drug delivery using silica nanotubes
The goal of all
sophisticated drug delivery systems is to deploy medications to
targeted parts of the body, nanotechnology provides the perfect trigger
to achieve this
![Sharath](/IMG/909/45909/sharath.gif)
Dr Aninda J Bhattacharyya and his students at the Solid State and
Structural Chemistry Unit (SSCU), Indian Institute of Science (IISc),
Bangalore, are exploring the possibilities of employing nanostructured
materials for diverse biotechnological and environmental applications.
They are making use of inorganic and hybrid (i.e. inorganic and
organic) based nanostructured materials for controlled drug delivery
and biosensing.
Dr Bhattacharyya says, “Recent experiments involving silica
nanotubes (SNTs) and other mesoporous oxide materials have been very
encouraging and we could see our efforts being useful to the medical
fraternity as these porous materials could be used as versatile hosts
for drug delivery and biosensing.”
The current methods of drug delivery exhibit specific problems that
scientists are attempting to address. The therapeutic benefits of
several drugs are limited or otherwise reduced because of the partial
degradation that occurs before they reach a desired target in the body.
The goal of all sophisticated drug delivery systems, therefore, is to
deploy medications intact to specifically targeted parts of the body
through a medium that can control the therapy’s
administration by means of either a physiological or chemical trigger.
To achieve this goal, researchers are utilizing the scope of micro-and
nanotechnology.
Drug delivery nanotechnology is just beginning to make an impact and
these IISc researchers are using their expertise in materials chemistry
to synthesize and manipulate molecules and supra-molecular structures
for producing drug delivery systems with programmed functions. In a
recent scientific paper by Dr Bhattacharyya with his student Shobhna
Kapoor published an article entitled ‘Ultrasound triggered
drug delivery and biosensing using silica nanotubes’ in the
journal of American Chemical Society, The Journal of Physical
Chemistry-C. The researchers have reported application of SNTs for
controlled drug delivery. (Ref: J Phys.Chem.C 2009, 113, 7155-7163)
“Inorganic porous materials have attracted considerable
attention as hosts for the immobilization of a variety of guest
molecules such as proteins, drugs and smaller biological molecules
(amino acids, peptides and vitamins). In spite of being in the early
stage, the inorganic nanostructured systems, such as, silica nanotubes
offer an attractive improvement over prevailing organic systems for
drug delivery,” says Dr Bhattacharyya.
In the present work, these IISc scientists have reported in detail the
procedures used for the preparation of the silica nanotubes. As a case
study, the scientists have studied the in-vitro drug release kinetics
of the common pain reliever Ibuprofen (IBU) in simulated body fluid
(SBF). The extent of IBU loading in the silica nanotubes and several
other parameters were monitored using sophisticated analytical tools,
such as, thermogravimetry analysis (TGA), X-ray diffraction (XRD), and
Fourier transform infrared (FTIR) spectroscopy.
IBU release kinetics was observed by monitoring the characteristic peak
at 264 nm of IBU by Ultraviolet-Visible (UV-VIS) spectroscopy
(Perkin-Elmer, Lambda 35 UV spectrometer). Ultrasound impulses (33 +/-2
kHz) of duration ranging from 0.5 min to continuous and with rest times
between successive impulses ranging from 0 to 30 min were given to the
SNT-IBU composite during release kinetics.
Dr Bhattacharyya observes, “In the present study, considering
the drug release yields, say over a period of 24 hours, for Ibuprofen
(IBU), our experimental results have been satisfactory. We believe that
the drug dosages obtained for the bare silica nanotubes and silica
nanotubes containing a coating of organic chemical groups can be
further tuned via optimization of the nanotube morphological parameters
that eventually leads to improved performance.”
To increase the efficiency of the drug release from
nanotubes, the researchers have experimentally shown the beneficial
effects of using short ultrasound pulses as external stimuli. The
purpose of application of an external stimulus will be highly
beneficial for the solvent molecules as well as solvated drug to
overcome several nanotube morphological heterogeneities. Further
investigations are currently on to study the impact of several
parameters on both degree of drug loading and the rate of release.
“We have demonstrated clearly the utility of a nanostructured
material such as silica nanotubes both as a controlled drug delivery
system and as a biosensor. We propose systems such as SNTs employed in
the present study, to serve as a prototype for generation of systems
having multiple functionalities for potential biotechnological
applications, especially for drug delivery,” adds Dr
Bhattacharyya.
Nanotechnology has a great potential in revolutionizing the drug
delivery field and the efforts of scientists such as Dr Bhattacharyya
and his team of students at IISc could someday save a great number of
lives.