Stimuli-responsive nanotheranostics

Nanomedicine is emerging as an enabling technology for addressing biomedical related challenges. Encouraging developments have been made particularly in overcoming the limitations associated with the conventional therapeutic and diagnostic agents while treating severe diseases including cancer. Recent research efforts have led to the evolution of nanomedicine from merely performing a therapeutic or diagnostic function to the systems that can perform therapeutic and diagnostic functions simultaneously, referred to as nanotheranostics or theranostics. The theranostic systems are capable of providing real-time feedback on the effectiveness of a particular treatment regimen and can help in adapting the treatment plan at an early stage. The real life impact of a theranostic system can be further augmented by introducing an element of stimuli (endogenous or exogenous) responsive release of the payload. The stimuli responsiveness can enhance the safety and efficacy of a nanomedicine via an on-demand and controlled release of a payload exclusively at the site of action and only when it is deemed necessary, as revealed by the diagnostic feature of the theranostic system. Such a provision of controlled treatment and real-time monitoring is expected to help in adjusting the treatment plan in a personalized manner, particularly, for diseases showing heterogeneity, malignancy, and adaptation. In the present chapter, we provide a comprehensive insight into the biological relevance of stimuli responsive character for developing a theranostic system. We further provide a detailed overview on the recent progress regarding the development of theranostic systems showing responsiveness to a variety of stimuli including pH, temperature, reducing agents, light, magnetic field and enzymes.