Preparation and performance of a stimuli-responsive drug delivery system: novel light-triggered temperature-sensitive drug-loaded microcapsules

Stimuli-responsive/smart drug delivery systems (DDSs), particularly those that use temperature as a stimuli-response factor to activate drug release, are the subject of recent research. A phase change material (PCM) is a popular thermally responsive material that can be used as a drug carrier and only when the system temperature is above the phase change point is the drug released following the phase change material changing from solid to liquid. In this study, a novel NIR light-triggered temperature-sensitive drug delivery system is developed for controllable release of acyclovir (ACV). For this purpose, a mixture of a phase change material (T38) and an ACV compound is first emulsified with copper oxide nanoparticles (CuO NPs) as a Pickering stabilizer and a photothermal conversion material, and then encapsulated with SiO2 to form a photothermal stimuli-responsive delivery system. This system shows a uniform spherical shape with a well-distinct core-shell structure, and is further experimentally proven to be able to controllably release drugs with solid-liquid transition of the phase change carrier upon temperature change. These results indicate that cumulative release of ACV can reach 51.2% at 40 °C within 20 hours, which is much higher than 27.3% release achieved below the melting point of T38. In addition, CuO NPs with excellent photothermal conversion ability endow the system with precisely controllable drug delivery via NIR light stimulation, where the cumulative drug release can reach 83.6% after 7 cycles of light stimulation, allowing controlled release at a specific time or location.

Recent Progress of Droplet Microfluidic Emulsification Based Synthesis of Functional Microparticles

The remarkable control function over the functional material formation process enabled by droplet microfluidic emulsification approaches can lead to the efficient and one-step encapsulation of active substances in microparticles, with the microparticle characteristics well regulated. In comparison to the conventional fabrication methods, droplet microfluidic technology can not only construct microparticles with various shapes, but also provide excellent templates, which enrich and expand the application fields of microparticles. For instance, intersection with disciplines in pharmacy, life sciences, and others, modifying the structure of microspheres and appending functional materials can be completed in the preparation of microparticles. The as-prepared polymer particles have great potential in a wide range of applications for chemical analysis, heavy metal adsorption, and detection. This review systematically introduces the devices and basic principles of particle preparation using droplet microfluidic technology and discusses the research of functional microparticle formation with high monodispersity, involving a plethora of types including spherical, nonspherical, and Janus type, as well as core-shell, hole-shell, and controllable multicompartment particles. Moreover, this review paper also exhibits a critical analysis of the current status and existing challenges, and outlook of the future development in the emerging fields has been discussed.

Fabrication of biodegradable hollow microsphere composites made of polybutylene adipate co-terephthalate/polyvinylpyrrolidone for drug delivery and sustained release

Sustained drug release has attracted increasing interest in targeted drug therapy. However, existing methods of drug therapy suffer drug action time, large fluctuations in the effective concentration of the drug, and the risk of side effects. Here, a biodegradable composite of polybutylene adipate co-terephthalate/polyvinylpyrrolidone (PBAT/PVP) consisting of electrospun hollow microspheres as sustained-released drug carriers is presented. The as-prepared PBAT/PVP composites show faster degradation rate and drug (Erlotinib) release than that of PBAT. Furthermore, PBAT/PVP composites loaded with Erlotinib provide sustained release effect, thus achieving a better efficacy than that after the direct injection of erlotinib due to the fact that the composites allow a high drug concentration in the tumor for a longer period. Hence, this work provides a potential effective solution for clinical drug therapy and tissue engineering using drug microspheres with a sustained release.

Progress in the application of sustained-release drug microspheres in tissue engineering

Sustained-release drug-loaded microspheres provide a long-acting sustained release, with targeted and other effects. There are many types of sustained-release drug microspheres and various preparation methods, and they are easy to operate. For these reasons, they have attracted widespread interest and are widely used in tissue engineering and other fields. In this paper, we provide a systematic review of the application of sustained-release drug microspheres in tissue engineering. First, we introduce this new type of drug delivery system (sustained-release drug carriers), describe the types of sustained-release drug microspheres, and summarize the characteristics of different microspheres. Second, we summarize the preparation methods of sustained-release drug microspheres and summarize the materials required for preparing microspheres. Third, various applications of sustained-release drug microspheres in tissue engineering are summarized. Finally, we summarize the shortcomings and discuss future prospects in the development of sustained-release drug microspheres. The purpose of this paper was to provide a further systematic understanding of the application of sustained-release drug microspheres in tissue engineering for the personnel engaged in related fields and to provide inspiration and new ideas for studies in related fields.