Fabrication and structural regulation of PLLA porous microspheres via phase inversion emulsion and thermally induced phase separation techniques

Preparation and morphology control of porous microspheres of different crystalline polymers

Controlling the surface morphology of degradable polymer porous microspheres with alkanes as porogens using the emulsion solvent evaporation method.

Construction and Evaluation of Traceable rhES-QDs-M-MS Protein Delivery System: Sustained-Release Properties, Targeted Effect, and Antitumor Activity

Recombinant human endostatin (rhES) is a protein drug with poor stability and short in vivo circulation time. The present study was therefore aimed at developing sustained-release lung targeted microspheres drug delivery system and evaluating its targeting efficiency using in vivo imaging techniques with quantum dots (QDs) as the imaging material. The oil-soluble QDs were coated with amphiphilic polymers to obtain a polymer-quantum dots micelle (QDs-M) with the potential to stably disperse in water. The rhES and QDs-M were combined using covalent bonds. The rhES-QDs-M microspheres (rhES-QDs-M-MS) were prepared using electrostatic spray technology and also evaluated via in vivo imaging techniques. The pharmacodynamics was further studied in mice. The rhES-QDs-M-MS (4-8 μm) were stable in an aqueous medium with good optical properties. The in vitro studies showed that the rhES-QDs-M-MS had sustained release which was maintained for at least 15 days (cumulative release >80%) without any burst release. The rhES-QDs-M-MS had a very high safety profile and also effectively inhibited the in vitro proliferation of human umbilical vein endothelial cells by about 70%. The pharmacokinetic results showed that the rhES could still be detected at 72 h in the experimental group which meant that the rhES-QDs-M-MS had a significant sustained-release effect. The rhES-QDs-M-MS had a better lung targeting effect and higher antitumor activity compared with the rhES. The traceable rhES-QDs-M-MS served as a promising drug delivery system for the poorly stable rhES proteins and significantly increased its lung-targeted effect, sustained-release properties, and antitumor activities.

Polyhydroxyalkanoate (PHA): applications in drug delivery and tissue engineering

INTRODUCTION

The applications of naturally obtained polymers are tremendously increased due to them being biocompatible, biodegradable, environmentally friendly and renewable in nature. Among them, polyhydroxyalkanoates are widely studied and they can be utilized in many areas of human life research such as drug delivery, tissue engineering, and other medical applications.

AREAS COVERED

This review provides an overview of the polyhydroxyalkanoates biosynthesis and their possible applications in drug delivery in the range of micro- and nano-size. Moreover, the possible applications in tissue engineering are covered considering macro- and microporous scaffolds and extracellular matrix analogs.

EXPERT COMMENTARY

The majority of synthetic plastics are non-biodegradable so, in the last years, a renewed interest is growing to develop alternative processes to produce biologically derived polymers. Among them, PHAs present good properties such as high immunotolerance, low toxicity, biodegradability, so, they are promisingly using as biomaterials in biomedical applications.

Emerging bone tissue engineering via Polyhydroxyalkanoate (PHA)-based scaffolds

Polyhydroxyalkanoates (PHAs) are a class of biodegradable polymers derived from microorganisms. On top of their biodegradability and biocompatibility, different PHA types can contribute to varying mechanical and chemical properties. This has led to increasing attention to the use of PHAs in numerous biomedical applications over the past few decades. Bone tissue engineering refers to the regeneration of new bone through providing mechanical support while inducing cell growth on the PHA scaffolds having a porous structure for tissue regeneration. This review first introduces the various properties PHA scaffold that make them suitable for bone tissue engineering such as biocompatibility, biodegradability, mechanical properties as well as vascularization. The typical fabrication techniques of PHA scaffolds including electrospinning, salt-leaching and solution casting are further discussed, followed by the relatively new technology of using 3D printing in PHA scaffold fabrication. Finally, the recent progress of using different types of PHAs scaffold in bone tissue engineering applications are summarized in intrinsic PHA/blends forms or as composites with other polymeric or inorganic hybrid materials.

Unique leafy morphology of poly(lactic acid) monoliths controlled via novel phase separation technology

Poly(lactic acid) (PLA) monoliths with unique leaf-like morphology and physical properties, designed by a newly developed thermally induced phase separation.