Our Technology: Targeted Starch Nanoparticles

At the core of GreenMark’s dental technology is its proprietary starch nanoparticle. Starch nanoparticles are small sub-micron particles that form highly stable aqueous dispersions. These particles are supplied by EcoSynthetix Inc. (TSX:ECO), a publicly traded company co-founded by Dr. Steven Bloembergen, GreenMark’s Chairman and CEO.

GreenMark’s dental technology was created through its collaboration with the University of Michigan (U-M), involving Dr. Nathan Jones, Dr. Brian Clarkson and Dr. Joerg Lahann. Upon receiving his Ph.D. from U-M, Dr. Jones joined GreenMark Biomedical to help further develop and commercialize this proprietary dental technology.

By virtue of these starch nanoparticles, GreenMark in essence has a technology platform that can be applied to multiple applications within healthcare. These small particles are not solid as hard mineral-based nanoparticles, but they are what we affectionally refer to as “nano-sponges”. We have learned through many years of rigorous research and development how to utilize the function of these particles to load content on the inside and place functional bonds on the outside of these particles. In so doing, we developed a general device for the targeted bio-delivery of healthcare solutions.

Our Technology and Dentistry—Targeted Starch Nanoparticles that Illuminate Carious Lesions

LumiCare™ Caries Detection Rinse is a novel approach to detecting and assessing caries. It will greatly enhance oral care by providing dentists a means to detect caries earlier. This capability allows for practitioners to administer the proper treatment, avoiding or delaying more invasive surgical restoration.

Sub-micron particles have not previously been used for the purpose of caries detection or assessment. The inherent high surface area of the particles provides for effective multi-functionalization to incorporate both targeting and imaging moieties within the same system.

GreenMark’s functionalized starch particles, developed with our collaborators at U-M, were first shown to selectively detect dental caries in vitro (read the Advanced Healthcare Materials article). Starch was chosen because it is non-toxic and is readily degraded by amylase enzymes present in saliva. When modified with a positive charge (cationic functionality), biobased starch particles target and adhere to carious lesions by associating with negative charges (anionic functionalities) characterizing the interior of the lesion.

This functionality is illustrated in Fig. 1 which is a cross section of an actual tooth with a carious enamel lesion that is not yet into dentin. Under polarizing light healthy enamel is blue while darker purple and brown/black colors indicate areas of greater porosity, corresponding to dentin (purple) and areas of decay (brown/black).

For an early non-cavitated carious lesion the surface normally remains intact, but open micropores allow acid to enter the enamel subsurface, such that the lesion becomes more and more porous until it eventually collapses into a cavity. Early detection and fluoride or remineralization treatment can prevent formation of fully developed cavities and help avert or delay the typical restorative cycle. The small size and positive charge of the GreenMark starch particles facilitates entry into the microchannels of carious lesions. The particles are tagged with a fluorescent dye so early non-cavitated carious lesions illuminate using a dental curing lamp common to most dental practices, revealing the size and location of carious lesions.

Fluorescein was selected as the fluorophore because it is safe and already being used in oral applications and in medical procedures. With its ability to be illuminated with a blue LED like those found in dental curing lamps, [Eagling, E. M. et al. “Ischaemic papillopathy. Clinical and fluorescein angiographic review of forty cases”, The British journal of ophthalmology, 58.12 (1974): 990], this technology provides a quick way of detecting early stage caries that may not be otherwise visible to the naked eye.

The starch-based composition of the particles is the ideal carrier materials that allows for rapid degradation by salivary amylase making them fully bio-resorbable, so lesions no longer fluoresce upon leaving the dental clinic.