Computational nanomedicine for mechanistic elucidation of bilayer nanoparticle-mediated release for tissue engineering

Aim: Temporal control of growth-factor release from nanoparticles is essential to many tissue engineering applications, yet remains a challenge due to its complicated behavior. The interplay between nanoparticle characteristics and release mechanisms can be captured using computational models. This study aims to develop two novel models to represent the release of bilayer nanoparticles. Materials & methods: Bilayer nanoparticles were prepared and characterized experimentally. ‘Local volume averaging’ and ‘Geno-Mechanistic’ models were developed and validated with experiments, and then used to identify critical release parameters and elucidate the release mechanisms. Results: Models presented an agreement with experimental data and successfully estimated transport/degradation parameters, which were closely associated with nanoparticle polymer mass ratio and crystallinity. Models suggested that despite relatively rapid core degradation, shell predominantly controlled overall release patterns. Conclusion: The developed models and computational frameworks offer a great potential for optimizing/tuning bilayer polymeric nanoparticles for tissue engineering applications.

Rate-programming of nano-particulate delivery systems for smart bioactive scaffolds in tissue engineering

Development of smart bioactive scaffolds is of importance in tissue engineering, where cell proliferation, differentiation and migration within scaffolds can be regulated by the interactions between cells and scaffold through the use of growth factors (GFs) and extra cellular matrix peptides. One challenge in this area is to spatiotemporally control the dose, sequence and profile of release of GFs so as to regulate cellular fates during tissue regeneration. This challenge would be addressed by rate-programming of nano-particulate delivery systems, where the release of GFs via polymeric nanoparticles is controlled by means of the methods of, such as externally-controlled and physicochemically/architecturally-modulated so as to mimic the profile of physiological GFs. Identifying and understanding such factors as the desired release profiles, mechanisms of release, physicochemical characteristics of polymeric nanoparticles, and externally-triggering stimuli are essential for designing and optimizing such delivery systems. This review surveys the recent studies on the desired release profiles of GFs in various tissue engineering applications, elucidates the major release mechanisms and critical factors affecting release profiles, and overviews the role played by the mathematical models for optimizing nano-particulate delivery systems. Potentials of stimuli responsive nanoparticles for spatiotemporal control of GF release are also presented, along with the recent advances in strategies for spatiotemporal control of GF delivery within tissue engineered scaffolds. The recommendation for the future studies to overcome challenges for developing sophisticated particulate delivery systems in tissue engineering is discussed prior to the presentation of conclusions drawn from this paper.