Tailoring Nanoparticle Properties Using Aculon Coating Technologies

Aculon has exclusively licensed patented technology from Princeton University for coating oxide surfaces, including metal oxide and yttria nanoparticles. This technology, along with other surface modification techniques, coating methods and materials developed at Aculon, serve as a platform on which nanoparticle surfaces can be tailored for a broad range of uses. One application of coating yttria particles has immediate commercial potential to effectively compete with Quantum dots for bioimaging and labeling systems. Bioimaging of cells with surface-modified yttria particles comprising peptides is illustrated in Figure 1.

Figure 1. Surface Modification of Yttria Particles for Bioimaging of Cells

Surface Modified Yttria Particles for Bioimaging and Anti-Counterfeit Systems

Yttrium oxide (Y₂O₃) is an air-stable, colorless substance widely used to make YVO₄Eu and Y₂O₃Eu phosphors that give the red color in TV picture tubes. This readily available material has recently been used for medical diagnostics and bioimaging. Utilizing self-assembled monolayers of phosphonates (SAMPs), Researchers at Princeton University were able to disperse yttria into solutions of water and solvents. By taking advantage of the luminescent properties in doped nanocrystalline yttria, scientists at Princeton University have used yttria nanoparticles to detect and image cells. Furthermore, better dispersivity of nanoparticles using SAMP treatments into organic and aqueous solvents enables the production of stable ink-jet solutions for anti-counterfeit and labeling systems.

Benefits of Aculon’s SAMP Technology for Yttria over Quantum Dots

According to Lux Research “Quantum dots were originally promoted for Quantum computing, optics, and solar cells, but its most likely immediate impact will be felt in multiplexed biological testing” There are others types of luminescent nanoparticles including Quantum dots, which are able to absorb and emit very specific wavelengths of light based on their size.

Quantum dots made from cadmium selenide (CdSe) are toxic to cells. A recent study reported that “exposure to CdSe Quantum dots resulted in cultured intestinal cell detachment and death.” Chemical bonding to Quantum dots is not stable in air and in vivo applications, therefore they need to be treated with surfactants, polymers, encapsulated into silica or other coatings. Such procedures, however, can be costly and will significantly increase the size of the particles.

Furthermore, surface modification of the coated Quantum dots may not have long-term stability under conditions required for their use in biodetection. Due to the necessity and difficulty of separating specific sizes of Quantum dots to absorb or emit certain wavelengths of light, the cost of such materials is high. The advantages of yttria particles treated with Aculon technology include:

• Functionality
• Size
• Processing
• Economics
• Toxicity

Functionality

Y₂O₃nanoparticles can be surface-modified with Aculon treatments to allow:

• Suspension in solvents or water for dispersion and ink jet printing
• More degrees of freedom to modify tailored receptors for bioimaging of cell
• Attachment of other functional layers via the SAMP treatments as an anchor
• Stronger crosslinking into organic matrices by selecting the appropriate functionality of the
• SAMP molecules
• Wavelength – Infrared excitation is less damaging and penetrates further into living tissue than UV (required for Quantum dots), therefore upconverting yttria is a better material for in vivo imaging

Size

• Thickness of Aculon’s surface treatments on yttria are 1-4 nanometers and are chemically bound as compared to treatments on Quantum dots, which are many times thicker.
• Surface treatments on Quantum dots are weakly bound and can desorb under mild conditions (especially in vivo), causing them to aggregate and lose functionality

Processing

• Simple, room temperature, solution-based procedure
• Quantum dots are very difficult to separate into discrete sizes, a necessary step for proper functioning

Economics

• Nanoparticles of Y₂O₃ are less than $5,000 per kg in small quantities (2009 Aldrich)
• Nanoparticles of CdSe and ZnS are approximately $10,000-$100,000 per kg (2-20x more expensive). (NanoTechOcean)

Toxicity

• Nanoparticles of Y₂O₃ (including surface-treated) are relatively non-toxic to cells.
• Cadmium Selenide is toxic

This information has been sourced, reviewed and adapted from materials provided by Aculon.

For more information on this source, please visit Aculon.