Two-step emulsification for the fabrication of homogeneous PCL microspheres encapsulating geniposidic acid with antioxidant properties

The mortality rate of neurological disorders is increasing globally,and natural antioxidant geniposidic acid(GPA)holds great potential in the treatment of neuronal oxidative damage.Nevertheless,its inherent instability constrains its pragmatic utilization.Herein,we introduced a drug delivery system capable of protecting unstable natural active compounds from degradation.Among the various methods for preparing drug-loaded microspheres,the emulsification-solvent evaporation technique is one of the most commonly employed due to its efficiency and simplicity.Nevertheless,this method results in microspheres with heterogeneous particle sizes.To address this limitation,we developed a two-step emulsification method involving stirring and homogenization.Using the biocompatible,synthetic,biodegradable polymer polycaprolactone(PCL)as the drug delivery carrier,we prepared GPA-loaded PCL microspheres via the two-step emulsification method.The results demonstrated that the microspheres possessed uniform particle size(polydispersity index=0.12),excellent drug loading capacity(∼4.86%),sustained drug release profiles(∼68.55%in 264 h),and biocompatibility(cell viability>85%).The in vitro tests showed that the microspheres exerted antioxidant effects by scavenging reactive oxygen species(ROS)induced by oxidative stress,thereby protecting neuronal cells from oxidative damage.This work presents a promising new approach for the treatment of neuronal oxidative damage.

Enzymes immobilized in wood-derived cellulose scaffold for constructing a novel modular bioreactor

Modular bioreactors can provide a flexible platform for constructing complex multi-step pathways,which may be a solution for maximizing reactions and overcoming the complexity of multi-enzyme systems.Here,we selected wood-derived cellulose scaffold as a support for enzyme immobilization and constructed the modular bioreactor.Cellulose scaffold was prepared after removing lignin from wood,followed by citric acid functionalization and the addition of glutaraldehyde finally allowed the cross-linking of enzymes.Three enzymes,horseradish peroxidase(HRP),glucose oxidase(GOD),and catalase(CAT),were separately immobilized,resulting in the immobilized enzyme amount to over 40 mg/g.The introduction of carboxyl groups from citric acid facilitated the rapid enzyme adsorption on the support surface and immobilized enzymes possess~65%expressed activity.Modular bioreactors were constructed by using the immobilized enzymes.With the immobilized HRP module,reactor showed desired catalytic performance with the phenol degradation rate of>90%.Also,a pH regulation can occur in the bioreactors for preserving enzyme activities and neutralizing acid products.In the GOD/CAT modular bioreactor,the cascade reaction with adjusting pH values can achieve a 95%yield of sodium gluconate and exhibit a favorable reusability of 5 operation cycles.