Stimuli-responsive drug delivery

In 2000, the first example of ELP diblock copolymers for reversible stimulus-responsive self-assembly of nanoparticles was reported and their potential use in controlled delivery and release was suggested [87]. Later, these type of diblock copolypeptides were also covalently crossUnked through disulfide bond formation after self-assembly into micellar nanoparticles. In addition, the encapsulation of l-anilinonaphthalene-8-sulfonic acid, a hydrophobic fluorescent dye that fluoresces in hydrophobic enviromnent, was used to investigate the capacity of the micelle for hydrophobic drugs [88]. Fujita et al. replaced the hydrophilic ELP block by a polyaspartic acid chain (D ). They created a set of block copolymers with varying... 

ELP-based triblock copolypeptides have also been used to produce stimulus-responsive micelles, and Chaikof and coworkers envisioned the possible application of these micelles as controlled drug delivery vehicles. These amphiphilic triblock copolymers were constructed from two identical hydrophobic ELP endblocks and a hydrophilic ELP midblock. Below the transition temperature, loose and monodispersed micelles were formed that reversibly contracted upon heating, leading to more compact micelles with a reduced size [90]. 

Many of the applications being developed for responsive gels are for controlled drug delivery, as reviewed by Gehrke and Lee, Hoffinan, Tanaka and Urry [1,28,87,88]. There are several ways in which these devices might respond to an appropriate stimulus. They could expand like pistons to pump drug from reservoirs, contract around reservoirs to squeeze out drug solutions, or function... 

Bio-responsive release the system modulates drug release in response to a biological stimulus (e.g. blood glucose levels triggering the release of insulin from a dmg delivery device). 

Soppimath KS, Aminabhavi TM, Dave AM, Kumbar SG, Rudzinski WE. Stimulus-responsive smart hydrogels as novel drug delivery systems. Drug Dev Ind Pharm 2002 28 957-974. 

Zha, L. Banik, B. Alexis, F. Stimulus responsive nanogels for drug delivery. Soft Matter 2011, 7 (13), 5908-5916. 

The reversible nature of DNA hybridization in response to an external stimulus causes this type of DNA-polymer hydrogels to have special properties, such as sol-gel phase transition and responsive releasing capability [93]. Thus, potential applications of these materials as label-free DNA sensing device or for controlled drug delivery have been discussed. Just a small portion of DNA is needed to achieve hydrogel responsiveness. 

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