Design of Methylprednisolone Biodegradable Microspheres Intended for Intra-articular Administration

This study aimed to design methyprednisolone (MP)-loaded poly(d,l lactide-co-glycolide) (PLGA) microspheres (MS) intended for intra-articular administration. MP was encapsulated in four different types of PLGA by using an S/O/W technique. The effects of β-irradiation at the dose of 25 kGy were evaluated on the chemical and physicochemical properties of MS and the drug release profiles. The S/O/W technique with hydroxypropylmethylcellulose (HPMC) as surfactant allowed obtaining MS in the tolerability size (7–50 µm) for intra-articular administration. The MP encapsulation efficiency ranged 56–60%. HPMC traces were evidenced in the loaded and placebo MS by attenuated total reflectance Fourier transform infrared spectroscopy. MS made of the capped PLGA DL5050 2M (MS 2M) and uncapped PLGA DL5050 3A (MS 3A) prolonged the release of MP over a 2- to 3-month period with a triphasic (burst release–dormant period–second release pulse) and biphasic release pattern, respectively. The β-irradiation did not significantly alter the morphology, chemical, and physicochemical properties of MS. The only variation was evidenced in the drug release for MS 2M in term of shorting of the dormant period. The minimal variations in the properties of irradiated PLGA MS, which are in disagreement with literature data, may be attributed to a radioprotecting effect exerted by HPMC

Rapid purification of sub-micrometer particles for enhanced drug release and microvesicles isolation

Efficient separation of sub-micrometer synthetic or biological components is imperative in particle-based drug delivery systems and purification of extracellular vesicles for point-of-care diagnostics. Herein, we report a novel phenomenon in spiral inertial microfluidics, in which the particle transient innermost distance (Dinner) varies with size during Dean vortices-induced migration and can be utilized for small microparticle (MP) separation; aptly termed as high-resolution Dean flow fractionation (HiDFF). The developed technology was optimized using binary bead mixtures (1–3 μm) to achieve ~100- to 1000-fold enrichment of smaller particles. We demonstrated tunable size fractionation of polydispersed drug-loaded poly(lactic-co-glycolic acid) particles for enhanced drug release and anti-tumor effects. As a proof-of-concept for microvesicles studies, circulating extracellular vesicles/MPs were isolated directly from whole blood using HiDFF. Purified MPs exhibited well-preserved surface morphology with efficient isolation within minutes as compared with multi-step centrifugation. In a cohort of type 2 diabetes mellitus subjects, we observed strong associations of immune cell-derived MPs with cardiovascular risk factors including body mass index, carotid intima-media thickness and triglyceride levels (P<0.05). Overall, HiDFF represents a key technological progress toward high-throughput, single-step purification of engineered or cell-derived MPs with the potential for quantitative MP-based health profiling.NRF (Natl Research Foundation, S’pore)MOE (Min. of Education, S’pore)MOH (Min. of Health, S’pore)Published versio