Development of the components of a controlled drug release system based on an electroresponsive hydrogel composed of carbon dots functionalized with curcumin.

A drug delivery system is one that seeks to deliver a therapeutic amount of a drug into an organism. Currently, these delivery systems are classified into conventional and modified release systems. In the conventional type, the active ingredient of the drug is delivered without any particular formulation design that allows it to target a specific site or control the rate of its release. In contrast, modified release systems possess a formulation design that allows them to control the rate of release and/or feature a configuration that facilitates the identification of a specific area for action. Thus, modified drug delivery systems offer obvious advantages over the conventional system such as a greater number of delivery alternatives, improved bioavailability and reduced secondary symptoms.

Among the vehicles designed as part of modified release systems are hydrogels. These materials are formed from natural or synthetic polymeric chains that interconnect with each other, producing a material with a three-dimensional macromolecular gel-like macromolecular structure. They have the capacity to retain high water content, are biocompatible, have visco-elastic properties similar to those of human tissues and allow the encapsulation of different species such as drugs or molecules of biomedical interest. Depending on the nature of the polymer, these hydrogels may possess the ability to exhibit physicochemical changes in response to external stimuli such as changes in pH, temperature or exposure to light or electric current. The variation of the physicochemical properties of the hydrogel to external stimuli allows control over the release conditions of a drug encapsulated within the hydrogel.

The use of an electric current as an external stimulus to modify the physicochemical properties of hydrogels has been important for the development of an accurate on-off drug release system. In the absence of current, the hydrogel maintains its three-dimensional structure, keeping the drug encapsulated. Isolation of the drug by its encapsulation minimizes the development of secondary symptoms. The release of the drug only occurs when an electric current undoes the interconnection of the polymeric chains, allowing the dispersion of the drug in the desired medium. By having a wide encapsulation capacity, the need to require several doses is eliminated, since the total concentration required can be included in a single system and its release can be controlled by the current flow used.

Despite having control over drug release, this type of material does not offer the intrinsic possibility of tracking the final destination of the drug after it is no longer contained within the hydrogel. An alternative for monitoring release is found in the use of fluorescent probes with dimensions in the nanometer range.

Carbon dots (CPs), recently discovered (2005), are nanoparticles that are part of the family of carbon-based nanostructures. These nanoparticles of quasi-spherical morphology, usually less than 10 nm in diameter, possess absorption and fluorescence properties that are located in the UV-Vis region of the electromagnetic spectrum. Carbon dots are synthesized from different organic precursors, they have colloidal stability and the addition of molecules of biomedical interest on their surface can be done by electrostatic, hydrophobic interactions or by the formation of covalent bonds.

The present project seeks to develop the components of a controlled drug delivery system based on an electroresponsive hydrogel. This material will serve as an encapsulating vehicle for carbon dots whose surface will be modified with the addition of curcumin, a phenolic compound whose activity against numerous types of cancer has been reported. The financing of this project through the Seed Capital Fund will allow the acquisition of the reagents and material necessary to carry out the synthesis of the electroresponsive hydrogel and the carbon dots functionalized with curcumin. It will also finance the characterization of these materials and in vitro exploratory experiments on the cytotoxicity of these materials in breast cancer cell lines.

Electroresponsive hydrogel; Controlled drug release system;
Carbon dots; Fluorescence; Curcumin; Breast cancer; Breast cancer