[0001] Due to the ever-increasing applications of nanoemulsions and nanoliposomes in biophysics,
physiology and medicine, many techniques have been developed over recent years to
manufacture them. Micro and nano sized emulsions and liposomes can be utilized as
carriers of encapsulated drugs. All existing methods to produce these emulsions have
serious drawbacks, namely rate of production, high production costs, low efficiency,
low quality, end-product contamination with metal particles during production, short
operating life of used ultrasonic processors and difficult scale-up procedures. Specifically,
for human drug delivery, liposomes (in the order of micro and nano size) are of growing
interest as carriers of drugs. For medical applications, these micro and nano spherical
shaped liposome carriers are of such a size to be able to travel freely throughout
the human body and through the body tissue. The liposomes may also be addressed by
means of specific coatings such as sugars and proteins to target them only to specific
tissues within the body. Through this new and innovative system of nanoemulsions and
nanoliposomes production (high efficiency, selective sizing, batch, or continuous
methods for commercial production) to produce the required liposomes, a highly effective
liposomal drug delivery can be achieved.
[0002] The formation of nanoemulsions and nanoliposomes requires intense shear forces and
significant energy deposition to break the original particles down to the nanometer
scale. High ultrasonic amplitudes are required for efficient nanoemulsions and nanoliposomes
production. The necessary shear forces are created by ultrasonic cavitation, which
produces violently and asymmetrically imploding vacuum bubbles and causes micro-jets
that disperse and break up the original oil droplets and liposomes down to the nanometer
scale. Known for many decades, this effect of high-amplitude ultrasound has been extensively
studied and successfully used in laboratory-scale research. However, none of the existing
ultrasonic liquid processors can generate the required amplitudes on the industrial
scale. Commercial implementation of high-power ultrasound has, therefore, been limited
to processes for which low amplitudes are sufficient (cleaning, simple deagglomeration,
mixing, macro-emulsification, etc.). As the high intensity ultrasonics can produce
nanosized liposomes, the moderate intensity can also agglomerate them thus rapid leaving
of the cavitation zone is of essence to high-yield production.
[0003] The invention describes an improved ultrasonic system based on Multifrequency, Multimode,
Modulated Sonic & Ultrasonic Vibrations, also known as MMM, enables a resolution of
the typically known and current production disadvantages, especially for nanoliposomes
production, in both laboratory and commercial batch and continuous modes. The improved
method enables a much narrower size distribution of resulting particles (typically
5nm to 100nm) along with a much shorter production time (which lies between factor
10 and 100 shorter of typical and known production times) along with a completely
non-contamination of the product.
[0004] Ultrasonic processor designed to produce nanoemulsions and nanoliposomes accordingly
to the invention is equipped with ultrasonic generator, piezoelectric transducers
and sonotrode submerged in liquid container, characterized in that the sonotrode has
at least one standing wave length at the average working frequency, is equipped in
an axial channel and two perpendicular radial through holes located at a node of the
sonotrode and at least two additional radial through holes located at the distance
not greater than 30 mm for the node of the sonotrode, while ultrasonic generator works
in an frequency sweeping mode with at least 500 Hz frequency span.
[0005] The invention is based on a novel sonotrode which consist set of channels realizing
sequential and progressive flow of the processed liquid. The processed liquid enters
the cavitation zone through holes located near the node and due to differential pressure
are pumped towards antinode direction through the axial channel and leaves the system
through the other set of holes. To ensure the pumping effect dimeter of inlet hole
(located at the node) must be greater than outlet holes. Additionally, node-hole provides
certain flexibility of the system making the intensity of ultrasonics greater via
Multimode-cavitation thus increased total intensity of ultrasound.
[0006] In addition, sequential and progressive waves pumping and fluid circulating effect
are realized via axial hole, enabled fluid under processing to supply perpendicular
and lateral holes that are producing vortices additionally intensifying cavitation
effect. As the processed liquid is leaves the zone of high intensity cavitation rapidly
there is no secondary effect of liposome coagulation.
[0007] Ultrasonic processor accordingly to the invention can operate in different Continuous
Wave, or Periodic Pulse-trains, including arbitrary and forced carrier signal modulations,
this way producing wideband and complex spatially distributed ultrasonic field structures.
[0008] Sonotrode accordingly to the invention, thanks to its geometry or shape and complex
acoustic field structure, is producing effects of particles size reduction, particles
agglomerations, multiphase liquids mixing and homogenization, forced and accelerated
solid particles precipitation and sedimentation. In addition, sonotrode according
to the invention is producing spherical shaping of complex inorganic, biological or
organic molecules (mostly based on different turbulent, vortex and spherical ultrasonic
field's formations, belonging to non-linear acoustics with Shear fields and evolving
transient waving effects). Long, stable, stationary, continuous ultrasonic irradiation
(like most of contemporary ultrasonic fluids processing equipment), is not at all
producing mentioned vortices and spherical fields formations necessary for non-linear
acoustic liquids processing.
[0009] Turbulence is created in a mixture of small single particles or molecules within
a carrier liquid. Turbulence, in the form of numerous small vortices within the bulk
liquid mixture, are created so enabling the agglomerate and sticking together of individual
particles and molecules in a highly concentrated and fast twisting or cyclonic manner.
[0010] The turbulence or vortices described above are created using a special submerged
rod like resonating element which is activated via a special external power supply
or electro-acoustic (or ultrasonic) generator. The resonating rod has axial and perpendicular
holes and channels, designed in a way that all of them are synchronously resonating,
producing different wave motions, vortices, and shear waves in both axial and radial
directions, when submersed. Subsequently, the uniquely designed resonating bar can
produce and propagate the required liquid vortices via a combination of low frequency
oscillations, ultrasonic frequency oscillations, including forced and frequency- sweeping
oscillating regimes with different signal modulations.
[0011] Operation of the generator in frequency sweeping mode is critical to activate various
vibrational modes of the sonotrode accordingly to the invention and provide cavitation
effect of the highest intensity.
Example and figures explanation:
[0012] The system accordingly to the invention was equipped with 14 nF, 20 kHz Langevin-type
piezoelectric transducers, 2 kW MMM-type ultrasonic generator, 20 I liquid container
and sonotrode as show on Fig. 1, submerged in the liquid container. The sonotrode
was manufactured from Φ60x610 mm Ti6Al4V alloy treated and aged rod which corresponds
to 2,5 λ (standing wavelength at 20 kHz in Ti6Al4V) and was equipped in axial through
hole of 20 mm diameter and two perpendicular, radial through holes of 20 mm diameter
located at each node and two sets of three through holes of 10 mm diameters per each
node located at the distance of 25 mm for each node. The sonotrode was submerged in
liquid container providing pressure field as show in Fig. 2 and was processing water
with 1% polyethylene glycol 1% iron acetate, providing 50-100 nm liposomes at 90%
yield after 30 minutes.
