Sonication in pharmaceuticals (with
special emphasis on probe sonicator)
by
Dr. Vikas Pandey
1. Introduction
1.1. What
is sonication?
Sonication is the act of applying sound energy to
agitate particles in a sample, for various purposes such as the extraction of
multiple compounds from plants, microalgae and seaweeds. Ultrasonic frequencies
are usually used, leading to the process also being known as ultrasonication or
ultra-sonication.
1.2. What
are ultrasonic waves and how they are produced ?
ultrasonic wave. Etymology: L, ultra, beyond, sonus,
sound. a sound wave transmitted at a frequency greater than 20,000 hz per
second, or beyond the normal hearing range of humans. The specific wavelength
is equal to the velocity divided by the frequency.
In most applications, ultrasonic
waves are generated by a transducer that includes a piezoelectric crystal that
converts electrical energy (electric current) to mechanical energy (sound
waves). ... Ultrasound may also be produced by a whistle or siren-type generator.
1.3. What
are some common applications of Sonication?
1.3.1.
In biological applications, sonication may be
sufficient to disrupt or deactivate a biological material. For example,
sonication is often used to disrupt cell membranes and release cellular
contents. This process is called sonoporation.
1.3.2.
Medical ultrasound (also known as diagnostic
sonography or ultrasonography) is a diagnostic imaging technique based on the
application of ultrasound. It is used to create an image of internal body
structures such as tendons, muscles, joints, blood vessels, and internal
organs.
2. Application
in Pharmaceuticals
In pharmacy,
sonication finds its application in optimizing dosage forms, specially novel
drug delivery systems, like in nanotechnology for evenly dispersing
nanoparticles in liquids. Additionally, it is used to break up aggregates of
micron-sized colloidal particles.
3. What
is a Sonicator?
A sonicator is a
powerful piece of lab equipment with an ultrasonic electric generator that
creates a signal to power a transducer. The transducer converts the electric
signal using piezoelectric crystals – crystals that respond directly to
electricity by creating a mechanical vibration. The sonicator preserves and
amplifies the vibration until it passes to the probe. The probe moves in time
with the vibration to transmit it to the solution and moves up and down
quickly. The sonicator operator can control amplitude based on the properties
of the solution. A small probe tip produces a more intense reaction than a
large probe tip, but a large tip reaches more of the solution.
4. What
is Sonication Process?
During
sonication, cycles of pressure form thousands of microscopic vacuum bubbles in
the solution. The bubbles collapse into the solution in a process known as
cavitation. This causes powerful waves of vibration that release an enormous
energy force in the cavitation field, which disrupts molecular interactions
such as interactions between molecules of water, separates clumps of particles,
and facilitates mixing. For example, in dissolved gas vibrations, the gas
bubbles come together and more easily leave the solution.
The energy from
sound waves creates friction in the solution, which creates heat. To stop a
sample from heating up and degrading, keep it on ice before, during and after
sonication.
If cells and
proteins are too fragile to withstand sonication, a gentler alternative is
enzyme digestion or grinding with sand.
5. What
is Cavitation?
The desired
effects from the ultrasonication of liquids – including homogenization,
dispersing, deagglomeration, milling, emulsification, extraction, lysis,
disintegration and sonochemical effects – are caused by cavitation. By introducing
high power ultrasound into a liquid medium, the sound waves are transmitted in
the fluid and create alternating high-pressure (compression) and low-pressure
(rarefaction) cycles, with rates depending on the frequency. During the
low-pressure cycle, high-intensity ultrasonic waves create small vacuum bubbles
or voids in the liquid. When the bubbles attain a volume at which they can no
longer absorb energy, they collapse violently during a high-pressure cycle.
This phenomenon is termed cavitation.
6. What
is Probe Sonicator?
A Probe
sonicator is a powerful piece of lab equipment with an ultrasonic electric
generator that creates a signal to power a transducer. ... The sonicator
preserves and amplifies the vibration until it passes to the probe. The probe
moves in time with the vibration to transmit it to the solution and moves up
and down quickly.
7. Parts
of Probe Sonicator.
