Bioresponsive matrices in drug delivery

Abstract

For years, the field of drug delivery has focused on (1) controlling the release of a therapeutic and (2) targeting the therapeutic to a specific cell type. These research endeavors have concentrated mainly on the development of new degradable polymers and molecule-labeled drug delivery vehicles. Recent interest in biomaterials that respond to their environment have opened new methods to trigger the release of drugs and localize the therapeutic within a particular site. These novel biomaterials, usually termed "smart" or "intelligent", are able to deliver a therapeutic agent based on either environmental cues or a remote stimulus. Stimuli-responsive materials could potentially elicit a therapeutically effective dose without adverse side effects. Polymers responding to different stimuli, such as pH, light, temperature, ultrasound, magnetism, or biomolecules have been investigated as potential drug delivery vehicles. This review describes the most recent advances in "smart" drug delivery systems that respond to one or multiple stimuli.

Electroactive Polymers and Coatings

“…Formation of a composite hydrogel occurs by embedding a particle into a hydrogel network, where the particle does not interact directly with the hydrogel [ 119 ]. All these approaches may be instituted in the synthesis of an electroresponsive hydrogel system, with selection based on swellability, structural integrity, and response required.…”

Localized, non-viral delivery of nucleic acids: Opportunities, challenges and current strategies

“…In contrast, bioresponsive drug delivery systems have been developed in recent years. These systems change their properties in response to a biological trigger such as changes of the pH, temperature, light or presence of biomolecules such as enzymes [83]. Such functions are highly desirable when designing hydrogels for NA delivery, allowing novel modes of drug release, e.g.…”

Nanostructures and Nanostructured Networks for Smart Drug Delivery

“…However, since the particles tend to aggregate reducing the paramagnetic features, they should be covered with polymers that can confer steric stability [108] or incorporated into micelles or cross-linked polymer networks [109]. Magnetic drug carriers containing temperature-responsive polymers possess three unique features: (i) visualization of the drug carrier into the body (MRI); (ii) tissue distribution controlled through an external magnetic field, which may be helped if decorated with cell ligands; and (iii) triggering of drug release due to a local increase in temperature when an alternating magnetic field is applied [27,110]. Different from other responsive systems that do not allow by themselves tissue guidance, drug carriers bearing magnetic particles can be concentrated into a specific region by applying high-gradient magnetic fields.…”

“…Although still far from such sophistication, clinical trials mainly carried out with anticancer agents formulated in advanced lipidic and polymeric particles have demonstrated the benefits of such an approach and some formulations are already available in the market [25]. Other areas of interest include (i) site-specific release of drugs unstable in physiological fluids (e.g., peptides, proteins) that should exert their effect only in certain tissues (e.g., inflamed, infarcted, infected), or that should enter into cells or cellular structures that are not easily accessible from the general circulation (for example, in gene therapy) and (ii) temporal or biorhythm-specific release of hormones, gastric acid inhibitors, β-blockers, or drugs for heart rhythm disorders or asthma [26][27][28]. The following sections deal with polymer-based nanostructures and nanostructured networks that apply the stimuli responsiveness to achieve an improved and precisely tuned ability for loading drugs and controlling their release.…”