As nanomaterials can be programmed to travel the body and selectively target the sites of disease, so using nanocarriers for drug delivery improves the accuracy of treatment inside the body while minimising side effects.
Nanomaterials are also able to deliver diagnostic agents that are typically not soluble in water or blood as well as significantly decrease the effective dosage. Although this method might seem ideal for treating diseases, nanocarriers for drug delivery are not without their challenges. Evan Scott, researcher at the Northwestern University, USA, said: “Controlled, sustained delivery is advantageous for treating many chronic disorders, but this is difficult to achieve with nanomaterials without inducing undesirable local inflammation.
“Instead, nanomaterials are typically administered as multiple separate injections or as a transfusion that can take longer than an hour. It would be great if physicians could give one injection, which continuously released nanomaterials over a controlled period of time.”
Scott, an assistant professor of biomedical engineering, has developed a new mechanism that makes that controlled, sustainable delivery possible.
How is sustained development possible?
Researchers have developed a nanocarrier formulation that, after forming into a gel inside the body at the site of injection, continuously releases nanoscale drugs for months. The gel can re-assemble into the nanocarriers, so after all of the drug has been delivered, no residual material is left to induce inflammation or fibrous tissue formation.
This system could, for example, enable single-administration injections that do not require boosters as well as a new way to deliver chemotherapy, hormone therapy, or drugs that facilitate wound healing.
Currently, the most sustained nanocarrier delivery system hold nanomaterials within polymer matrices. These networks are implanted into the body, where they slowly release the trapped drug carriers over a period of time.
Problems and solutions
The problem comes after the delivery is complete as the network remains inside the body, often provoking a foreign-body response. The leftover network can cause discomfort and chronic inflammation in the patient.
To bypass this issue, nanocarriers for drug delivery have been established using self-assembled, filament-shaped materials, which are then loaded with a drug. When they are crosslinked together they form a structure that is similar to structural tissue in the human body.
After the filaments are injected into the body, the resulting hydrogel network functions as a drug depot that slowly degrades by breaking down into spherical nanomaterials called micelles, which are programmed to travel to specific targets. Because the network morphs into the drug-delivery system, nothing is less behind to cause inflammation.