Nanomaterials have long been implicated as the potential capsules in which we will deliver the drugs of the future. While familar nanomaterials such as nanotubes and fullerenes have been studied extensively and show promise for this application, their biocompatibility remains i
n question. Detonation nanodiamonds (NDs) are highly structured diamond-based materials that can form in sizes as small as 2nm. These NDs are very appealing for future drug delivery applications due to the ease of their production (literally through TNT detonations), stability, and their high ordered structure. Most importantly, this ordered structure appears to make these NDs less harmful to cells and less likely to cause inflammation.
A study from Dean Ho's lab at Northwestern recently used these ND structures to deliver chemotherapeutic drugs to murine macrophage cells and human colon cancer cells. The group was able to cluster ND particles into 50-100nm clusters which bound to the cancer drug, DOX, upon the addition of salt. This binding is typically stable until salt concentration lowers, at which point the drug can be released. Moreover, the high surface area on the 1000's of tiny NDs that compose the delivery structure allows a high amount of drug to be delivered by this mechanism.When the group tested DOX-loaded NDs on murine and human cells, they found that they could control the release of DOX to occur at the target sites. Morover, the group found that there was no imflammation in cells caused by presence of the ND's, and upon drug release the clusters breakdown into tiny ND components that appear to be harmless to the body. The stability of these NDs also allows for significant functionalization, which is essentially chemistry performed on the surface of the molecules, and can be used to facilitate targeting to the right areas of the body. While work on these NDs for drug delivery is still in its early stages, NDs hold promise in drug delivery because of their stability, safety, and ease of functionalization.(FIGURE from CNN.com)
A monomer is a small chemical building block that can chemically bond with other monomers to form more complex structures called polymers (i.e. A-A-A-A-A-A). While many polymers consist of repeats of the same monomer, some called copolymers are the result of two or more different monomers linking together in chains (i.e. A-B-A-A-B-B). Block copolymers are examples of copolymers that can be joined to eachother to form a meta-structure with multiple domains (see figure). A recent paper published in ACS Nano has demonstrated the use of block copolymers in a nanofilm for coating medical devices.
In this paper, Dean Ho, et al. add a polymethyloxazoline-polydimethylsiloxan- polymethyloxazoline (PMOXA-PDMS-PMOXA) copolymer with dexamethazone - together referred to as PolyDex - to an implant using a method called Langmuir-Blodgett deposition. The PolyDex was able to "cloak" the implant as it was found to be necessary and sufficient to prevent immune response from cells in normal mice after the implantation of two polyethylene disks.
This PolyDex nanofilm can contribute significantly in the medical device field as devices become smaller and more fragile. The ability of these nanofilms to prevent the accumulation of inflammatory cells may help protect implants from post-implantation damage and increase the mortality of implants in the future. Moreover, this coating may aid in the reduction of overall inflammation of the implant site that may reduce further complications that occur after surgeries. The small thickness of these films at 4 nanometers per layer will make this film extremely versitile as it will allow manufacturers to apply it to the smallest of implants.
While these nanofilms are still very early in development, they show great promise in medical devices, for which inflammation is an all too common issue.
