Preparation Of PLGA Magnetic Microspheres By SPG Membrane Emulsification And Their Application

Bioactive polymeric biomaterials,as an important frontier area which is the pervasion and combination of polymer and life sciences.It is an important feature of the development of polymer science in the past 50 years.High molecular weight poly（lactic acid）poly（hydroxyacetic acid）（PLGA）,is one of the most biodegradable materials in the world because of its non-toxic and approval from FAD.PLGA is usually used as biocompatible carrier material and skeleton material of microspheres.PLGA magnetic microspheres（PLGA-MMs）and porous PLGA microspheres have attracted much attention from academia in recent years.The use of polymer microspheres as a carrier of magnetic particles can not only increase the biocompatibility of the body,but also prevent the nanoparticles from directly entering the body which can result in adverse effects on the body,such as the toxic side effects relied on the size of the nanoparticles.Besides,due to the magnetic particles concentrated in the microspheres,the magnetic separation properties can be greatly improved,which is very helpful for the application of detection.Due to complex extraction process,high cost and instability of natural enzyme,mimetic enzymes have gradually become a research hotspot.Using nanoparticles as nanozymes has attracted great interest since the intrinsic peroxidase-like activity of Fe₃O₄ nanoparticles was revealed.Here the PLGA-MMs containing Fe₃O₄ nanoparticles were studied as the candidate of catalase and peroxidase mimic.The context includes:（1）The PLGA-MMs were prepared by SPG membrane emulsification and high speed homogenization.The PLGA-MMs’surface morphology and structure could be controlled by changing the feeding ratio of Fe₃O₄@OA nanoparticles and PLGA.SEM,EDS elemental analysis and LSCM were used to characterize the PLGA-MMs that validate the effectiveness of morphological control.This study provides a simple strategy for tailoring the structure and morphology of PLGA-MMs,especially for constructing porous or Janus structures.（2）The peroxidase-like activity was demonstrated in the acidic condition by using PLGA-MMs to catalyze the oxidation reaction of chromogenic substrates TMB（3,5,3’,5’-tetramethylbrnzidine,positively charged）to generate color reaction in the presence of H₂O₂.In the pH dependence test,it was found that the peroxidase-like activity of PLGA-MMs disappeared in the neutral or alkaline condition.Using oxygen electrode,it was also found that PLGA-MMs can catalyze the decomposition of H₂O₂,which means PLGA-MMs is a catalase mimic in the neutral or alkaline condition.