Polymerisation-Induced Self-Assembly (PISA) as a straightforward formulation strategy for Stimuli-Responsive Drug Delivery Systems and Biomaterials: Recent Advances

Stimuli-responsive amphiphilic block copolymers have emerged as promising nanocarriers for enhancing site-specific and on-demand drug release in response to a range of stimuli such as pH, the presence of redox agents, or temperature. The formulation of amphiphilic block copolymers into polymeric drug-loaded nanoparticles is typically achieved by various methods (e.g. oil-in-water emulsion solvent evaporation, solid dispersion, microphase separation, dialysis or microfluidic). Despite the several progresses that have been made, there remain many challenges to overcome to produce reliable polymeric systems. The main weakness of the above methods is that they imply very low solid contents (< 1 wt%) and multiple-step procedures, thus limiting their scope. Recently, a new self-assembly methodology, polymerisation-induced self-assembly (PISA), has shown great promise in the production of polymer-derived particles in a straightforward one-pot approach, whilst facilitating high yield, scalability, and cost-effectiveness for pharmaceutical industry protocols. We therefore focus this review primarily on the most recent studies involving in the design and preparation of PISA-generated nano-objects which are responsive to specific stimuli, thus providing an insight into how PISA may become an effective formulation strategy for the preparation of precisely tailored drug delivery systems and biomaterials, while some of the current challenges, conundrum, and limitations are also critically discussed.