Smart polymers for the controlled delivery of drugs – a concise overview

Abstract

Smart polymers have enormous potential in various applications. In particular, smart polymeric drug delivery systems have been explored as “intelligent” delivery systems able to release, at the appropriate time and site of action, entrapped drugs in response to specific physiological triggers. These polymers exhibit a non-linear response to a small stimulus leading to a macroscopic alteration in their structure/properties. The responses vary widely from swelling/contraction to disintegration. Synthesis of new polymers and crosslinkers with greater biocompatibility and better biodegradability would increase and enhance current applications. The most fascinating features of the smart polymers arise from their versatility and tunable sensitivity. The most significant weakness of all these external stimuli-sensitive polymers is slow response time. The versatility of polymer sources and their combinatorial synthesis make it possible to tune polymer sensitivity to a given stimulus within a narrow range. Development of smart polymer systems may lead to more accurate and programmable drug delivery. In this review, we discuss various mechanisms by which polymer systems are assembled in situ to form implanted devices for sustained release of therapeutic macromolecules, and we highlight various applications in the field of advanced drug delivery.

Smart Radiation Therapy Biomaterials

“…Such systems with programmed sequential release proffer more versatility for controlled release in biomedical applications and could be adapted for radiotherapy biomaterials. Adaptations of PLGA (PLGA–PEG–PLGA triblock copolymers) and chitosan are also thermosensitive polymers [70]. In response to a small temperature change, such thermosensitive polymers undergo abrupt change in their solubility to release payloads.…”

“…Indeed, the benefits of polymers for drug delivery may be largely pharmacokinetic. This is specifically useful with a depot formulation created in the matrix from which the payload can slowly elute, maintaining a high local concentration of the payload over an extended period [70]. …”

Weak bond-based injectable and stimuli responsive hydrogels for biomedical applications

“…6, 8–11 Regardless of the challenges, these advanced materials are enabling the development of new solutions for treating various human diseases, such as diabetes, cardiac repairs, wound healing and cancer theranostics. 12–16 Although we attempted to cover as much as possible researches published in the last six years that are related to the weak bond-based injectable hydrogels for biomedical applications, it is impossible to cover every single paper in this field. We attempt to cover the most extensively studied weak bond-based hydrogels in this review.…”

Novel Pentablock Copolymers as Thermosensitive Self-Assembling Micelles for Ocular Drug Delivery

“…24,25 Copolymers of N-isopropylacrylamide (NIAAm) display an ‘on/off’ drug release 26 with the ‘on’ state at a lower and the ‘off’ state at a higher temperature than LCST, and give a pulsatile scheme to drug release. 27 Generally, LCST systems are utilized to control the release of drugs, particularly proteins.…”