Company USA

In the following text, we will provide a description of our nano-device and novel porous material and identify critical criteria regarding development and use of this device for encapsulation applications.  We specifically describe the use of our nanoporous particles for the treatment of cancer, but the particles could be used to encapsulate perfumes as well as the current encapsulant (a cell lysing agent). 

We will also describe our capabilities, facilities, and equipment related to developing nano-devices using the company’s novel nanomaterial (i.e. highly porous nanoparticles). 

The Platform:  Porous-Particle Nanodevice

Porous Nanoparticles

The company’s platform nanotechnology (i.e. nanosponge) device for the treatment of cancer is shown schematically in Figure 1.  The device is a highly porous particle, produced using an advanced material formation process.  The porous particle structure is currently filled with a therapeutic/cytolytic agent and the particles are injected into a specific body fluid.  The nano-sized particles are randomly shaped, generally ellipsoidal with a particle size in the range of 100nm to 5m.  Continuous pores in the particles can range in size from 10-200nm.  The company's materials are highly porous (porosity greater than 90%) so a large dose of therapeutic agent (encapsulant) can be loaded into the pores of the nanoparticle.  The dose is much larger than could be coated on the particle surface of the same size or possibly incorporated into a degradable solid particle.

During the particle fabrication process, a “stealth” coating can be formed on the surface of the particles that allows them to circulate for extended time periods in body fluids.  A ligand coating can also be added following fabrication to facilitate particle binding to target cells (Figure 1A) that over-express a specific receptor, such as tumor cells.  Further, a contrast agent can be incorporated during fabrication to facilitate imaging of the particles through magnetic resonance following binding to the target tissue.

Following injection, body fluids surround the particle and fill the pore structure by capillary action.  Another coating can be placed over the therapeutic agent within the pores to delay therapeutic agent hydration.  This delay of agent hydration protects it from being degraded by material in the body fluid.  The agent is released from the particles after they bind to the target cells (Figure 1B).  The protective/delay layer thereby maximizes the amount of agent that is delivered to the target cell.  This released agent provides an intended therapy; and following agent release, the particle slowly biodegrades or is removed by natural means.

The nanodevice effectively acts as a “ferry” to carry agent to the tumor site.  The key advantage of this approach is that the agent is not exposed directly to the body fluid because it is inside the pores and it is coated with a delay coating.  This sequestering of agent reduces the agent being degraded by body fluids and also minimizes interaction of the agent with the body’s immune system components (e.g. macrophages, neutrophils, antibodies).  The resultant effect is a more potent delivery of agent and less of a chance for eliciting an immune response.

To fabricate the multifunctional therapeutic nanodevice shown in Figure 1, several key staff capabilities are required, namely the ability to:  1) Form micro and nano-sized porous particles, 2) Incorporate a stealth coating material and possibly a contrast agent in the particles during fabrication, 3) Determine particles properties including size, shape, porosity, pore size, and stealth coating density, 4) Coat a targeting ligand on the particle surface for targeted therapy, 5) Fill the particle’s pores with a therapeutic agent (encapsulant), and test its release characteristics, 6) Provide a coating to protect the agent and delay its release, 7) Determine the ligand coating density, and 8) Test various aspects of 
 

Figure 1.  Schematic of Therapeutic Nanodevice

the particle in vitro and in vivo (e.g., circulation time, tissue biodistribution, and tumor regression in animal models).

The company's staff and its collaborators (Local materials company and OSU) have experience and capabilities outlined above based on research funded by the NCI on the Unconventional Innovations Program (UIP).  All of the above activities are currently being pursued for porous particles in the 1m range (See Figure 2).  Smaller porous particles can be formed by various means .

Figure 2.  SEM photographs (20,000X) of porous particles following sonication

 to reduce the mean particle size.

As mentioned previously, key factors in delivery a therapeutic agent to a targeted site is precision in timing of circulation within the body as well as timely release of the agent to the cells/tumors of interest.  Previous work performed by the staff at the company and its collaborators have shown that these criteria can be met through in vitro and in vivo models.  Figure 3 shows flow cytometry data of target cells bound and killed by ligand-coated porous particles loaded with the cytolytic agent.  The ligand of choice in these experiments was the Epidermal Growth Factor (EGF).  Several cell lines were exploited because of their innate over-expression of the EGF receptor, and the cells were placed in the presence of cytolytic loaded porous particles having the EGF ligand bound to their surface.  As one can see in Figure 3, specific particle/cell binding occurred and 97% of the target cells were killed within 2 minutes in a 50% concentration of serum supplementation.  The serum was added to simulate a typical blood serum level; since it has been well documented in literature that free lysing agent is inactivated in the presence of serum.  Also shown in Figure 3, is the protection of the control cells that do not express the targeted ligand.  The control cells (CHO cells) had a minimal amount of nonspecific death, roughly 4%.  Additional studies have also shown that particles around the size of a micron or less can remain in circulation of a rat for up to 30 minutes.  This residence time translates into an acceptable time for circulation in the human body to find the targeted cells/tumors. 

Figure 3.  Flow Cytometric Analysis of Nontargeted and Targeted cells
by the company's porous particles