Nanogels: Stimuli-responsive Drug Delivery Carriers
Nanogels are nano-sized networks which are composed of hydrophilic or amphiphilic polymer chains. They can also be defined as the nanosized particles formed by cross-linked bifunctional networks of polyion and non-ionic polymers for delivery of polynucleotides. They are designed to spontaneously absorb biologically-active molecules through formation of hydrogen or hydrophobic interaction and are newly developed as carriers for drug delivery. These nano-sized particles swell when they come in contact with solvents, forming a cross-linked network. These have high drug-loading capacity, biocompatibility and biodegradability as the main key points for an effective drug delivery system. Nanogels used as drug delivery carriers can be stimuli-responsive. The stimuli-responsive device transports a drug in spatial, temporal or dosage controlled fashions. The implementation of stimuli-responsive devices requires the use of biocompatible materials that are susceptible to a specific stimulus. A wide range of stimuli-responsive nanocarriers, having different sizes, architectures and surface properties, have been designed and can be used for treatment of various chronic diseases by adjusting environmental factors (exogenous and endogenous) for targeted drug delivery. So, the aim of this review article is to describe the stimuli-responsive nanocarriers for drug delivery and briefly summarize their potential biomedical applications along with their implementation in recent clinical trials.