ACOUSTIC WAVE-TRIGGERED NANOCARRIERS FOR TARGETED DRUG DELIVERY AND RELEASE

Abstract

The present invention relates to the targeted controlled delivery of therapeutic agents using a novel acoustically activated drug delivery system with multiple types of nanocarriers. The system under study incorporates the acoustically triggered polymer micelles (101), bubble-integrated liposomes (102), acoustic hologram-guided nanoparticles (103), thermoresponsive hydrogel nanoparticles with acoustic heating (104), acoustic metamaterial-enhanced nanocarriers (105), and DNA origami acoustic nanomachines (106). With such nanocarriers, it is possible to respond to specific acoustic stimuli produced by an external acoustic wave generator and therefore, spatial and temporal control of drug release is strongly presented. Multi-modal control in this system provides for the sequential or combinatorial release of a drug, enhanced tissue penetration, and real-time adjustability; in the latter, the control is realized by acoustic holography, cavitation effects, and engineered nanomaterials.

Specification

Description:Acoustically-Triggered Polymer Micelles: In this embodiment, specially designed polymer micelles serve as nanocarriers. The micelles consist of amphiphilic block copolymers that have a hydrophobic core, capable of encapsulating hydrophobic drugs. Innovation lies in the incorporation of acoustic-sensitive linkages into the polymer structure.

Mechanophores are, therefore, the outstanding cleverly placed molecular units in polymer backbones that induce known chemical changes on the application of mechanical force. Here, acoustic waves of certain frequencies with given amplitude have programmed the mechanophores to be sensitive to mechanical stress.

The mechanophores, under appropriate acoustic stimulation, display conformational change or bond cleavage. This process is thereafter followed by a train of events that lead to the disruption of micelles and hence drug release. The acoustic parameters can be conveniently fine-tuned such that the system behaves to have either rapid burst release or more steady and sustained release profile.

Bubble-Integrated Liposomes: This composition is composed of principles from liposomal drug delivery as well as acoustic cavitation effects. The nanocarriers comprised liposomes that include gas-filled microbubbles within their bilayer structure.

The liposome membrane is filled with an optimal concentration of phospholipids and cholesterol for stability and biocompatibility. Encapsulated within this membrane is a microbubble, typically filled with perfluorocarbon gas. The microbubbles are designed to resonate at specific ultrasound frequencies.

In this process, known as acoustic cavitation, microbubbles oscillate and then collapse when they meet corresponding ultrasound waves. The stress due to this collapse, for a very short moment opens up pore structures in the liposome membrane through which the drug encapsulated within it escapes. As such, by using ultrasound parameters to modulate the degree and duration of this pore opening, control is also exercised over the kinetics of drug release.

Acoustic Hologram-Guided Nanoparticles: This advanced generation incorporates principles of acoustic holography into responsive nanoparticles in order to allow for very locally and patterned drug delivery.

This system comprises of two major parts:
• An acoustic hologram generator which can generate a complex three-dimensional field of pressure
• Nanoparticles sensitive to specific acoustic pressure patterns

An acoustic hologram generator uses an array of transducers and sophisticated algorithms in order to form the acoustic wave front into a very complex pressure landscape above the target tissue. The nanoparticles were formed as core-shell structures, with the material for the shell chosen to exhibit a mechanical behaviour which would deform or break under a certain threshold acoustic pressure.

Acoustic holography allows one to pattern the acoustic pressure field so that high-pressure regions build up exactly where drug release is necessary. Only nanoparticles within those distinct domains will break apart and release their payload, which allows for unprecedented spatial control over drug release. Advanced release patterns that include sequential activation of populations of different nanoparticles can be achieved.

Thermoresponsive Hydrogel with Acoustic Heating: The thermal response of focused ultrasound is exploited to release drugs from thermosensitive hydrogel nanoparticles.

Nanocarriers consist of a biocompatible thermoresponsive polymer, such as PNIPAM and its derivatives. These have a sharp phase transition at a specific temperature, and this characteristic makes it termed as a lower critical solution temperature (LCST). Below the LCST, the polymer hydrogel is swollen, and it may retain encapsulated drugs while collapsing above LCST and expelling its contents.

New in this approach is a responsive heating element inside the hydrogel matrix that responds to ultrasound. Heating elements may be plasmonic nanoparticles or even specially designed sonosensitizers for efficient acoustic energy-to-heat conversion. Focusing ultrasound on these elements induces local heating, and triggered phase transition from within the hydrogel initiates the drug-release process.

Control of ultrasound intensity and duration can precisely control the generated temperature and hence govern drug release profiles with excellent fine-tuning. Thus, it integrates the power of hydrogel-based delivery systems with the non-invasive advantage of ultrasound activation.

Acoustic Metamaterial-Enhanced Nanocarriers: This is the most advanced example in which acoustic metamaterial principles are used to imagine nanocarriers possessing unprecedented sensitivities and specificities toward acoustic stimulation.

The nanocarriers are designed in a core-shell architecture, where the shell is an acoustic metamaterial engineered to possess properties not found in nature. Thus, the acoustic metamaterial shell will be tailored for unusual effects under certain acoustic frequencies-for example, extreme focusing or amplification of acoustic energy.

For example, the structure of the metamaterial could be an alternating sequence of concentric layers, changing the acoustic properties or perhaps a more complex three-dimensional architecture. When the transmitting acoustic wave reaches the chosen match for frequency, the metamaterial shell channels and concentrates acoustic energy towards the core holding the therapeutic payload.

This concentrated energy is capable of exciting the release mechanism, which may be tailored to rely on mechanical disruption, phase change, or other physical effects. The highly selective nature of this acoustic metamaterial enables highly selective activation with minimum side release of drugs and offers the control of multiple populations of drugs independently by utilizing different acoustic frequencies.

DNA Origami Acoustic Nanomachines: This is a DNA nanotechnology-acoustic-responding material hybrid that results in programmable nanoscale devices able to deliver drugs.

The nanocarriers are based on DNA origami structures, which is the complex three-dimensional shape formed by folding DNA strands. The DNA origamis are custom-designed to include both the drug-carrying compartments and acoustic-responsive elements.

It is fundamentally seen in the application of mechanosensitive DNA structures including G-quadruplexes or i-motifs that undergo conformational changes when there is an applied mechanical stress. These are embedded at strategic points in the DNA origami framework. For particular acoustic wave parameters, these mechanosensitive elements undergo a conformational change, thereby inducing a structural cascade in the whole DNA origami. The reorganization in such a way that previously sealed compartments open up, releasing encapsulated drug molecules. With the DNA origami approach, one can create nanocarriers of precise size and shape, as well as drug loading capacities. Since DNA is programmable, structures can be designed that respond to multiple acoustic frequencies; hence, there is a possibility for sequential or combinatorial release from a single nanocarrier. The combined molecular precision of DNA nanotechnology with the non-invasive control of acoustic activation opens up new possibilities for systems considered to be among the most sophisticated drug delivery systems.

The description further defines the invention below.
Acoustically-Triggered Polymer Micelles: The important feature of the embodiment is an acoustically-triggered polymer micelle. Imagine a spherical particle, no larger than a few hundred nanometers, having an architecture of core-shell. The hydrophilic outer shell provides a means of free movement through the bloodstream. Meanwhile, the inner core is hydrophobic- exactly suited to capture drugs that are not miscible in water.

What distinguished these micelles was the inclusion of mechanophores among the polymer chains. These were rather intelligent molecular structures, acting as minuscule stress sensors and optimally positioned for acoustic wave-induced response. Following the proper frequency stimulus, this triggers a shift-maybe a ring-opening reaction or a cleavage of a bond. This shift then propagates out through the micelle assembly with its carefully optimized hydrophilic/hydrophobic balance being compromised.

As the micelle destabilizes, it starts to break just like the wave br[.]/the sandcastle crumbling. The drug molecules that before settled snugly in the hydrophobic core are now exposed to environmental surroundings. One great benefit of this system is that it is tunable. Altering the polymer composition and designing the mechanophore can result in the production of micelles that respond to certain acoustic frequencies and amplitudes. This can lead to a sharp, high-precision control over where and when the drug is released.

These micelles could be packed full of antibiotics and might travel harmlessly around the body until an acoustic beam meets them right at the infection site. The effect is a highly targeted drug delivery that results in greatly diminished systemic side effects.

Bubble-Integrated Liposomes: This embodiment, inspired by the submarine sonar world, applies the concept on a nanoscale. The not-so-standard lipid vesicles-they are actually really high-tech submarines, each of which carries a payload of drugs-and of course, with a novel sonar responsive system.

The innovation lies in the fact that there are gas-filled microbubbles within the liposome membrane. The kind of gas usually used is perfluorocarbon. The bubbles are selected such that their sizes and locations are such that they resonate at known ultrasound frequencies. Magic happens when these microscopic bubbles resonate with the ultrasonic waves penetrating them.

The bubbles start oscillating, expanding and then rapidly contracting. This oscillation builds localized stresses in the membrane of the liposome. With increased intensity, the oscillations become extremely violent until the bubble collapses in a phenomenon called cavitation.

The cavitation event is essentially a small explosion that produces shock waves, together with jet streams, within the liquid. These forces temporarily disrupt the liposome membrane by creating transient pores through which the drug inside the vesicle escapes into the surrounding tissue.

The beauty of the system lies in its control aspect. Parameters of ultrasound can be adjusted-the frequency, intensity, and duration-to finely modulate the degree of membrane disruption. This allows for both kinetic modulation of drug release and fine-tuning between the very rapid burst release and slow, sustained delivery.

In addition, ultrasound-responsive liposomes may be designed with integrated bubbles that respond to multiple frequencies. This may open the door to the possibility of sequential release, where sequential populations of liposomes are activated at different times or locations within the organism.

Acoustic Hologram-Guided Nanoparticles: It is a quantum leap in targeted drug delivery, integrating the latest advances in acoustic technology with sophisticated design in nanoparticles. Essentially, at its core, this system uses acoustic waves not just as a trigger but also as a sort of sophisticated 3D guidance system for releasing drugs under control.

There is a masterful acoustic hologram generator leading this band. It shapes sound waves into complex, three-dimensional patterns using an array of carefully coordinated transducers. These are not simple pressure waves at all but intricately sculpted fields of pressure and velocity that can focus energy at precise points in space.

The nanoparticles in this system are also extremely advanced. They would be designed with a pressure-sensitive shell, probably a polymer that will deform or break when there is a certain threshold of acoustic pressure. The drug cargo can be contained at the core of each nanoparticle.

When the acoustic hologram is turned on, it created a three-dimensional pressure landscape within the target tissue. It can be rather complex, almost like a three-dimensional chessboard, in which every square represents a different pressure zone. Only in the high-pressure zones will the nanoparticles break open and release their cargo.

Such control over spatial release has never been witnessed before. It will allow the designs for drug release patterns that match the anatomy and pathology of the target tissue. For example, if a patient is diagnosed with a brain tumor, an acoustic hologram can be molded to exactly fill the irregular boundaries of the tumor, thus the medicine will release only inside that diseased tissue while letting healthy brain regions intact.

The acoustic hologram can be further dynamically adjusted in real time; this would mean that the release patterns of drugs could be dynamically changed as a patient's condition would change or as targeting is necessary to move to different locations within the body.

Thermoresponsive Hydrogel with Acoustic Heating: that is an interesting coupling of the precision of ultrasound with the versatility of smart hydrogels. The system uses sound to regulate temperature, and the temperature in turn regulates drug release-a beautiful cascade of cause and effect at the nanoscale.

The star of the show is the thermoresponsive hydrogel nanoparticle. Made from polymers such as poly(N-isopropylacrylamide) (PNIPAM), these hydrogels have a remarkable property: they can switch between a swollen hydrated state and a collapsed dehydrated state depending upon temperature.

The trigger point is known as the lower critical solution temperature, or LCST. Below this threshold, the hydrogel is something akin to a sponge, swollen and full of water; drug molecules are trapped inside its matrix. But above this temperature, it expels all water content-along with any drugs it's carrying-off in an instant.

But how do we heat these nanoparticles in a controlled, localized manner? Well, this is where the acoustic element comes into play. These are components that are embedded within the matrix of the hydrogel and are designed to generate heat. In other words, they are plasmonic nanoparticles that resonate with some particular frequencies of ultrasound, or sonosensitizers - molecules that convert acoustic energy into heat very efficiently.

When focused ultrasound is applied, these elements act like miniature heaters by elevating the hydrogel's temperature beyond its LCST. The hydrogel collapses, and the drug payload is expelled into the surrounding tissue.

The beauty of this system lies in the precise control it allows. One can accurately modulate into the heating process by tuning the intensity and duration of the ultrasound, thereby creating any desired fast burst to a slow sustained release.

This would permit the synthesis of various different batches of nanoparticles, each with slightly different LCST or heating elements responsive to a slightly different ultrasound frequency, and therefore enable drug release at different times and in stages, all under the control of the same external device that generates the ultrasound.

Acoustic Metamaterial-Enhanced Nanocarriers: This embodiment takes full advantage of the extraordinary properties of acoustic metamaterials to manufacture nanocarriers having unprecedented sensitivity and specificity to sound waves.

Instead, the heart of this system is an acoustic metamaterial shell surrounding each nanocarrier. Not simple materials, these structures are intricately engineered to behave in ways that seem to violate conventional physics in their interaction with sound waves.

Picture it as a nanoparticle with concentric shells. Each of these shells is made up of materials whose acoustic properties are all different from one another. There is this phenomenon that can be seen when a specific sound wave hits this structure. The concentric shells help create a converging and amplifying the acoustic energy towards the center of the nanoparticle, which then bears the drug payload.

This focusing effect can be so strong that it is like wrapping a tiny acoustic lens around every nanocarrier. Sound waves, which otherwise would pass innocently through tissue, are caught and focused, then trigger the opening mechanism at the core.

The release mechanism itself could take many forms. It might be a mechanical disruption, in which the focused acoustic energy literally shakes the core apart. Or it might be a phase-change material that turns from a solid to a liquid when subjected to the amplified acoustic pressure.

Where the magic is, actually, is really in its selectivity. So by designing a certain metamaterial structure, we can create nanocarriers that, say, only respond to very, very, very specific acoustic frequencies-only their parents can call them. So, in theory, we would have multiple populations of nanocarriers in the body, where they're each loaded up with different drugs, and each responds to a different ultrasound frequency.

One ultrasound device could selectively trigger the release of different drugs in a precisely choreographed sequence, simply by changing the frequency of emitted sound waves.

DNA Origami Acoustic Nanomachines: DNA Origami Acoustic Nanomachines realize ultimate nano bioconjugation through unlocking the potential of DNA as a programmable medium for sound-sensitive structures with unprecedented precision.

At the heart of these systems lie DNA origami structures that are achieved through folding long strands of DNA like origami on a nanoscale and represent complex 3D shapes. These frameworks, therefore, become building blocks for our acoustically responsive drug delivery vehicles.

Structures could consist of integrated mechanosensitive DNA in origami forms; in other words, it could be G-quadruplex, i-motifs, or other DNA structures which change their conformation according to mechanical stress.

When the correct acoustic waves strike these structures, then the mechanosensitive elements change conformation. "It is similar to pulling a thread in a cleverly woven tapestry," says Professor Simmel. "It just sets off a cascade of structural changes throughout the entire DNA origami structure.".

These changes can be engineered to open up previously sealed compartments of the DNA structure, thus releasing the drug molecules that were trapped inside. With DNA engineering, it's now possible to develop structures that respond to a wide range of acoustic frequencies, prompting sequential changes in their structure, and potentially, the release of multiple drugs.

The true flexibility of this system lies in its programability. We could create structures with almost arbitrary complexity based on the principles of DNA nanotechnology. We could build such DNA origami capsules that release drugs not only in response to sound but change shape to facilitate cellular uptake, or we could make structures that assemble into larger complexes upon acoustic activation.

Further, due to its lack of cytotoxic properties, the biological compatibility of DNA makes these structures particularly promising candidates for in vivo applications. They can be engineered to degrade in a safe manner after serving their purpose in the body, leaving no harmful residues behind.

In summary, although the six examples differ in their approach, they share a common value in the novel exploitation of acoustic energy for controlled drug release. Each offers unique benefits-ranging from the simplicity of the polymer micelles to the programmability of the DNA origami. Together, they represent a major step forward in our ability to deliver the right drug, to the right place, at the right time-all orchestrated by the subtle power of sound waves.

Method of performing the invention
The true brilliance of this invention lies not just in the individual embodiments, but in how they can be seamlessly integrated to create a sophisticated, multi-layered drug delivery system. Let's explore how these components work together to revolutionize targeted therapeutics.

At the core of our system are the acoustically-triggered polymer micelles (Embodiment 101). These serve as our primary drug carriers, circulating through the bloodstream with their payload safely encapsulated. Their polymer composition is carefully tuned to respond to specific acoustic frequencies, providing the first layer of control over drug release.

Working in tandem with these micelles are the bubble-integrated liposomes (Embodiment 102). While the micelles excel at carrying hydrophobic drugs, the liposomes are perfect for water-soluble medications. This dual-carrier approach allows us to deliver a wider range of therapeutic agents. The microbubbles in the liposome membranes are designed to resonate at frequencies slightly different from those triggering the polymer micelles, enabling independent control over the release of different drug types.

The precision of our drug delivery is dramatically enhanced by the acoustic hologram-guided nanoparticles (Embodiment 103). This system acts as the conductor, orchestrating where and when our carriers release their payload. By generating complex 3D acoustic fields, we can create "hot spots" of high acoustic energy that correspond exactly to the target treatment areas. When our micelles and liposomes enter these zones, they encounter the specific frequency and amplitude of acoustic waves needed to trigger drug release.

But what about deeper tissues, where acoustic waves might be attenuated? That's where our thermoresponsive hydrogel with acoustic heating (Embodiment 104) comes into play. These nanocarriers are designed to accumulate in tissues over time. When triggered by lower-energy acoustic waves that can penetrate deeper into the body, they generate localized heat, creating secondary release zones for our temperature-sensitive drug carriers.

To further enhance our system's sensitivity and specificity, we incorporate the acoustic metamaterial-enhanced nanocarriers (Embodiment 105). These act like acoustic amplifiers, making our entire system more responsive to subtle acoustic signals. By fine-tuning their structure, we can create carriers that respond to very specific acoustic signatures, allowing for even more precise control over drug release patterns.

Finally, for the most complex delivery scenarios, we deploy our DNA origami acoustic nanomachines (Embodiment 106). These programmable structures can be designed to respond to multiple acoustic triggers in sequence, allowing for staged release of different drugs or the activation of secondary therapeutic mechanisms. They can also be programmed to change shape upon acoustic activation, facilitating tissue penetration or cellular uptake of the released drugs.

In practice, these systems work together like a well-oiled machine. Imagine treating a complex tumor with multiple drug-resistant regions. We begin by injecting a mixture of our various nanocarriers, each loaded with different medications. The acoustic hologram generator maps out the tumor's structure and creates a customized acoustic field. As our carriers circulate, they encounter different acoustic zones:

In easily accessible regions, the polymer micelles and bubble-integrated liposomes release their initial payload. Deeper in the tumor, the thermoresponsive hydrogels activate, creating local hot spots that trigger secondary drug release. In highly specific regions, perhaps where we've identified particular genetic markers, the metamaterial-enhanced carriers and DNA origami structures respond to precise acoustic signatures, delivering specialized drugs or activating complex therapeutic sequences.

Throughout this process, real-time imaging feedback allows us to adjust the acoustic field, ensuring optimal drug distribution even as the tumor environment changes. The result is a dynamic, adaptive drug delivery system that can tackle complex diseases with unprecedented precision.

This integrated approach showcases the true potential of acoustic-mediated drug delivery. By combining these varied mechanisms, we've created a system that's greater than the sum of its parts - a versatile, precise, and controllable method for delivering the right drugs to the right places at the right times. It's not just a new way to deliver drugs; it's a paradigm shift in how we approach targeted therapeutics.
, Claims:1. An acoustic wave-activated drug delivery system comprising:
(a) a plurality of nanocarriers, wherein said nanocarriers comprise:
(i) acoustically-triggered polymer micelles (101) with mechanophore-incorporated polymers;
(ii) bubble-integrated liposomes (102) with gas-filled microbubbles in their membranes;
(iii) acoustic hologram-guided nanoparticles (103) responsive to specific acoustic pressure patterns;
(iv) thermoresponsive hydrogel nanoparticles (104) with acoustic heating elements;
(v) acoustic metamaterial-enhanced nanocarriers (105) with pressure-focusing shells; and
(vi) DNA origami acoustic nanomachines (106) with mechanosensitive DNA structures;
(b) at least one therapeutic agent encapsulated within said nanocarriers;
(c) an external acoustic wave generator capable of producing multiple frequencies and amplitudes; and
(d) a control system for modulating said acoustic wave generator;
wherein said nanocarriers are designed to release said therapeutic agent in response to specific acoustic stimuli, and
wherein said nanocarriers are configured to work in concert to provide multi-stage, targeted drug delivery.

2. A method for targeted drug delivery comprising:
(a) administering to a subject a composition comprising the nanocarriers of claim 1;
(b) allowing said nanocarriers to accumulate at a target site;
(c) generating acoustic waves using said external acoustic wave generator; and
(d) modulating said acoustic waves to selectively activate one or more types of said nanocarriers,
thereby triggering controlled release of said therapeutic agent at said target site;
wherein said acoustic waves are modulated to create a three-dimensional acoustic hologram corresponding to the geometry of said target site;
wherein multiple types of said nanocarriers are activated in a predetermined sequence to achieve staged drug release;
wherein said target site is a tumour, and said acoustic waves are modulated to match the tumour's irregular boundaries;
wherein, the method further comprising the step of adjusting said acoustic waves in real-time based on feedback from an imaging system.

3. The system of claim 1, wherein said acoustically-triggered polymer micelles (101) comprise amphiphilic block copolymers with hydrophobic cores capable of encapsulating hydrophobic drugs.

4. The system of claim 1, wherein said bubble-integrated liposomes (102) comprise phospholipids and cholesterol optimized for stability and biocompatibility.

5. The system of claim 1, wherein said acoustic hologram-guided nanoparticles (103) are responsive to three-dimensional acoustic pressure fields generated by said acoustic wave generator.

6. The system of claim 1, wherein said thermoresponsive hydrogel nanoparticles (104) comprise poly(N-isopropylacrylamide) (PNIPAM) or its derivatives.

7. The system of claim 1, wherein said acoustic metamaterial-enhanced nanocarriers (105) comprise concentric layers with alternating acoustic properties designed to focus acoustic energy.

8. The system of claim 1, wherein said DNA origami acoustic nanomachines (106) incorporate G-quadruplexes or i-motifs as mechanosensitive elements.

9. The system of claim 1, wherein said nanocarriers are configured to respond to different acoustic frequencies, enabling sequential or combinatorial drug release.

10. The system of claim 1, further comprising an imaging system for real-time monitoring of nanocarrier distribution and activation.

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