PCL Microspheres Research Articles

Effect of poly(ε-caprolactone) microspheres on population pharmacokinetic/pharmacodynamic model of a simple coumarin

This study aims to evaluated the impact of poly(ε-caprolactone) (PCL) microspheres on the pharmacokinetics and pharmacodynamics (PopPK/PD) of 6-methylcoumarin (6MC). For this, PCL microspheres loaded with 6MC were prepared using the emulsification-evaporation method. Particle size, zeta potential, drug loading, and entrapment efficiency were characterised by dynamic light scattering and UV spectrophotometry. In vitro release and pharmacokinetics in Wistar rats were assessed for free and encapsulated 6MC. Anti-inflammatory activity was evaluated using the carrageenan-induced paw edoema model, with PopPK and PopPK/PD models developed. Microspheres showed diameters between 2.9 and 7.1 µm, zeta potentials of −10 to −15 mV, and drug loading of 0.24 mg/mg. Encapsulation efficiency was 45.5% to 75.9%. PopPK models showed enhanced absorption and distribution, with increased anti-inflammatory potency of encapsulated 6MC. PCL microspheres significantly improved the pharmacokinetic and pharmacodynamic profiles of 6MC, enhancing its therapeutic potential for lipophilic drugs.

Surfactant-free fabrication of curcumin-loaded emulsion coatings on titanium for biomedical applications

Biofunctional emulsion coatings of curcumin-loaded poly(ɛ-caprolactone)/polyvinyl alcohol-hydroxyapatite (Cur-loaded PCL/PVA-HA) were developed on the titanium (Ti) plates without using any surfactant. Firstly, stable oil-in-water emulsions with different water/oil (W/O) ratios (9:1, 7:1, 5:1 and 3:1) were prepared by using the uniform PVA-HA slurry as a water phase and the Cur-loaded PCL solution as an oil phase. The diameter of the oil droplets in those emulsions mostly ranged from 4 to 6 µm. Subsequently, the emulsions were formulated into coatings on Ti through a spin-coating process. The obtained emulsion coatings consisted of Cur-loaded PCL microspheres that were evenly embedded in the PVA-HA matrix, and their phase composition was identified by the FT-IR analysis. The emulsion coatings were hydrophilic and displayed a gradual increase in water contact angles with the decrease of the W/O ratio. Moreover, abundant bone-like apatite aggregates were formed on the emulsion coatings, suggesting their excellent in vitro bioactivity. In addition, the emulsion coatings exhibited a sustained drug release behavior within 2–48 h, and the release process was mainly controlled by diffusion. The present study provides a new perspective on green and facile fabrication of functional emulsion coatings.

Using embossing ice particulate method to prepare polyvinyl alcohol/pullulan hydrogels with surface open pores loaded with microspheres for breast cancer treatment

In the post-operative treatment of breast cancer, early prevention of locoregional recurrence is crucial to avoid metastasis of cells from leftover microtumor tissues. The limitations in conventional drug delivery systems show a growing clinical demand for disease-specific drug-releasing systems. This study explores a novel poly(vinyl alcohol)/pullulan (PVA/PUL) hydrogel system for local drug delivery in post-operative breast cancer treatment. Hydrogel was produced by combination of lyophilization and embossing ice particulate techniques to create microspheres loaded open pores on the hydrogel surface for localized release of doxorubicin-loaded polycaprolactone microspheres (DOX-PCL-MSs). PVA/PUL hydrogel was successfully crosslinked with glutaraldehyde and stabilized hydrogel structure has possessed slow degradation rate and increasing water retention through 12 days. Release of DOX after 7 and 16 days from DOX-PCL-MSs loaded hydrogels were slower with a 6.2 ± 8.9 % and 56.6 ± 4.5 % release compared to 60.9 ± 14.6 % and 76.8 ± 19.7 % release from free DOX loaded hydrogel since DOX release was controlled by PCL microspheres. When interacted with human breast cancer cell line (MCF-7), DOX-PCL-MSs were able to disrupt cell and spheroid morphology after 7 days at concentrations as low as 12 μg/mL loaded DOX. In vitro cytotoxicity study has showed that, DOX-PCL-MSs loaded hydrogel was able to decrease MCF-7 viability after 7 days of incubation with controlled release of DOX. While free DOX releasing hydrogel has lost cytotoxic activity even after 4 days of incubation. Furthermore, ability of PVA/PUL hydrogel to support L929 cell attachment was shown in the study, suggesting hydrogels potential for promoting tissue regeneration after anti-cancer treatment. The study reveals that PVA/PUL hybrid hydrogels loaded with DOX-PCL-MSs has impactful potential in post-surgical treatment of breast cancer.

Evaluation of the self-healing capabilities and resistance to thermal cycling of a shape-memory epoxy coating containing polycaprolactone microspheres

The aim of this work was to prepare a shape-memory epoxy coating containing polycaprolactone microspheres (SMEP-PCL) and study its resistance to thermal cycling, which is yet to be evaluated in coatings prepared with similar approaches, as well as further characterize its self-healing capabilities. Firstly, the prepared microspheres were characterized by scanning electron microscopy (SEM) and laser diffraction. Afterwards, the dispersion of the PCL microspheres in the coating was examined and experiments were conducted with differential scanning calorimetry (DSC) and Fourier-transform infrared spectroscopy (FTIR) to determine the glass transition temperature and investigate the curing reaction of the prepared coating, respectively. Then, the healing promoted by the reversible plasticity and the melt of the polycaprolactone microspheres mechanisms were studied by SEM, Raman Imaging, electrochemical impedance spectroscopy (EIS) and scanning vibrating electrode technique (SVET). Finally, thermal cycling tests were conducted and the samples were later visually evaluated for thermal stress damage and by EIS and pull-off adhesion strength tests. The SMEP-PCL of the present work was able to reproduce the self-healing results obtained from previous reports, even improving upon the self-healing efficiency obtained in other studies, in the SVET experiment. The results of the EIS measurements after the thermal cycles, pointed out to a minor reduction on the barrier properties of the SMEP and SMEP-PCL, which should be further investigated. Nonetheless, the adherence of both coatings was unhindered by the thermal cycles, which is a highly positive result for the future application of coatings based on this approach. Also, the SMEP-PCL exhibited substantially higher average values of adhesion strength compared to the SMEP, showing that the addition of PCL microspheres significantly improved the adherence of the coating and signaling great compatibility between them. This work also underlines how the healing efficiency of coatings with this approach are highly dependent on the type and extension of damage, as the healing observed in the two types of damage studied were exceedingly different.

Synthesis and characterization of Erythromycin loaded PLGA and PCL microspheres: Antimicrobial application

Synthesis and characterization of Erythromycin loaded PLGA and PCL microspheres: Antimicrobial application

Bioactive PCL microspheres with enhanced biocompatibility and collagen production for functional hyaluronic acid dermal fillers.

Polymeric microspheres containing magnesium hydroxide (MH) and a bioactive agent (BA), such as apocynin (APO) and astaxanthin (ATX), have been prepared as functional dermal fillers with enhanced physicochemical and biological performance. In this study, polycaprolactone (PCL)-based microspheres were produced with a uniform size of about 30-40 μm by utilizing a membrane emulsification device. MH from the PCL/MH microspheres effectively neutralized acidic products from PCL degradation. For in vitro cell experiments, when acidic degradation products (6-hydroxycaproic acid, HCA) were treated with MH, the acidic pH was neutralized to induce wound healing and suppress inflammation. The microspheres comprised of BA had a sustained release of the BA, without an initial burst release. Remarkably, the ATX added into the microspheres was maintained for 16 weeks and displayed positive attributes, such as tissue regeneration and collagen production improvement, as noted by in vivo testing. Overall, these results suggest that the bioactive PCL microspheres containing ATX have excellent potential as a functional dermal filler for skin aesthetics and facial plastic surgery.

Star-shaped poly(ε-caprolactones) with well-defined architecture as potential drug carriers

The present study reports the potential application of star-shaped poly(?-caprolactones) with different number of arms as new drug delivery matrix. Linear and star-shaped PCL ibuprofen loaded microspheres were prepared using oil-in-water (o/w) solvent evaporation technique and characterized with FTIR, DSC, XRD and SEM analysis. High yield, encapsulation efficiency and drug loadings were obtained for all microspheres. FTIR analysis revealed the existence of interactions between polymer matrix and drug, while the DSC analysis suggested that drug was encapsulated in an amorphous form. SEM analysis confirmed that regular, spherical in shape star-shaped microspheres, with diameter between 80 and 90 ?m, were obtained, while quite larger microspheres, 110 ?m, were prepared from linear PCL. The advantage of using starshaped PCL microspheres instead of linear PCL was seen from drug release profiles which demonstrated higher amount of drug released from star-shaped polymer matrix as a consequence of their branched, flexible structure. Microspheres prepared from the polymers with the most branched structure showed the highest amount of the released drug after 24 h. Finally, cytotoxicity tests, performed using normal human fibroblasts (MRC5), indicated the absence of cytotoxicity at lower concentrations of microspheres proving the great potential of star-shaped PCL systems in comparison to linear ones.

Drug-releasing Microspheres for Stem Cell Differentiation.

The ability of stem cells to differentiate into specialized cells make them a valuable tool for therapeutic applications. 3D bioprinting, a subset of additive manufacturing, uses bioinks composed of cells and biomaterials to create living tissues. The use of bioactive factors like small molecules and proteins can promote stem cell differentiation into the desired cell phenotypes for tissue regeneration. Small molecules can accelerate the process of regeneration in tissue engineering, maintain bioactivity in a biological environment, and minimize the costs associated with this process. Additionally, they can be encapsulated in specialized drug-delivery devices called microspheres for controlled release. Microspheres are small (1-1000 μm) spherical particles usually made from biodegradable and biocompatible polymers that can be loaded with drugs and other bioactive components. They can then be integrated into stem-cell-laden bioinks used to form bioprinted tissues, where they will release the encapsulated drug and promote differentiation of stem cells into the desired mature cell type. Microspheres can be widely used to encapsulate a broad range of therapeutic agents, including hydrophilic and hydrophobic small molecule drugs, DNA, and proteins. The release of encapsulated molecules occurs through degradation and erosion of the polymer matrix. This article provides detailed protocols for fabricating and sterilizing drug-releasing microspheres made from poly-ε-caprolactone, a promising biodegradable polymer often used for controlled drug delivery due to its biocompatibility and biodegradation kinetics. Additional protocols describe characterization of the loading and size of microspheres as well as incorporation of microspheres into a fibrin-based bioink for 3D bioprinting. © 2021 Wiley Periodicals LLC. Basic Protocol 1: Fabrication of drug-releasing PCL microspheres Support Protocol 1: Preparation of microspheres for determination of encapsulation efficiency by HPLC Support Protocol 2: Preparation of microspheres for SEM analysis Basic Protocol 2: Incorporation of microspheres into fibrin-based bioink.

Preparation of hollow PCL microspheres by o/w single emulsion-solvent evaporation method in the presence of graphene nanopowders

Preparation of hollow PCL microspheres by o/w single emulsion-solvent evaporation method in the presence of graphene nanopowders

Blending of PLGA-PEG-PLGA for Improving the Erosion and Drug Release Profile of PCL Microspheres.

PCL has a long history as an industrialized biomaterial for preparing microspheres, but its hydrophobic property and slow degradation rate often cause drug degeneration, quite slow drug release rate and undesirable tri-phasic release profile. In this study, we used the blending material of PLGA-PEG-PLGA and PCL to prepare microspheres. The microspheres degradation and drug release behaviors were evaluated through their molecular weight reduction rate, mass loss rate, morphology erosion and drug release profile. The hydrophilic PLGA-PEG-PLGA is expected to improve the degradation and drug release behaviors of PCL microspheres. Microspheres in blending materials exhibited faster erosion rates than pure PCL microspheres, forming holes much quickly on the particle's surface for the drug to diffuse out. A higher proportion of PLGA-PEG-PLGA caused faster degradation and erosion rates. The blending microspheres showed much faster drug release rates than pure PCL microspheres. With blending of 25wt% PLGA-PEG-PLGA, the release rate of microspheres speeded up significantly, while, with a further increase of PLGA-PEG-PLGA proportion (50%, 75%, 100%), it accelerated a little. The microspheres with PCL/PLGA-PEG-PLGA of 1/1 exhibited a linear-like drug release profile. The results could be a guideline for preparing microspheres based on blending materials to obtain a desirable release.

PCL/HA Hybrid Microspheres for Effective Osteogenic Differentiation and Bone Regeneration.

The purpose of this study is to develop a bioactive bone graft based on polycaprolactone (PCL, synthetic polymer; used in clinical practices as a grafting material for craniofacial bone defects) and hyaluronic acid (HA, bioactive natural polymer; known as a promoting substance for bone regeneration) that would be fabricated by clinically available procedures (mild condition without toxic chemicals) and provide bioactivity for sufficient period, and thus effectively induce bone reconstruction. For this, PCL/HA hybrid microspheres were produced by a spray-precipitation technique using clinically adapted solvents. The HA was stably and evenly entrapped in the PCL/HA hybrid microspheres. It was demonstrated that the PCL/HA hybrid microspheres provide an appropriate environment for proliferation and osteogenic differentiation of human periosteum-derived cells (hPDCs) (in vitro) and allow significantly enhanced bone regeneration (in vivo) compared with PCL microspheres without HA. The PCL/HA hybrid microspheres can be a simple but clinically applicable bioactive bone graft for large-sized bone defects.

Development of a polyvinyl alcohol/sodium alginate hydrogel-based scaffold incorporating bFGF-encapsulated microspheres for accelerated wound healing

In the present study, a hybrid microsphere/hydrogel system, consisting of polyvinyl alcohol (PVA)/sodium alginate (SA) hydrogel incorporating PCL microspheres is introduced as a skin scaffold to accelerate wound healing. The hydrogel substrate was developed using the freeze-thawing method, and the proportion of the involved polymers in its structure was optimized based on the in-vitro assessments. The bFGF-encapsulated PCL microspheres were also fabricated utilizing the double-emulsion solvent evaporation technique. The achieved freeze-dried hybrid system was then characterized by in-vitro and in-vivo experiments. The results obtained from the optimization of the hydrogel showed that increasing the concentration of SA resulted in a more porous structure, and higher swelling ability, elasticity and degradation rate, but decreased the maximum strength and elongation at break. The embedding of PCL microspheres into the optimized hydrogel structure provided sustained and burst-free release kinetics of bFGF. Besides, the addition of drug-loaded microspheres led to no significant change in the degradation mechanism of the hydrogel substrate; however, it reduced its mechanical strength. Furthermore, the MTT assay represented no cytotoxic effect for the hybrid system. The in-vivo studies on a burn-wound rat model, including the evaluation of the wound closure mechanism, and histological analyses indicated that the fabricated scaffold efficiently contributed to promoting cell-induced tissue regeneration and burn-wound healing.

Controlled Release of Ropivacaine from Single-Armed (1-PCL) and Four-Armed PCL (4-PCL) Microspheres

Sustained release of anesthesia has shown great promise in the treatment of chronic pain in patients. In this research, we used neutralized ropivacaine as an anesthesia and poly(ε-caprolactone) (PCL) with different architectures to systematically study how these architectures affect the release of ropivacaine. After optimizing the parameters of the preparation of microspheres, ropivacaine-loaded 1-PCL microspheres and 4-PCL microspheres were obtained. Fourier Transform infrared spectra (FT-IR) and X-ray diffraction spectra (XRD) confirmed that ropivacaine was encapsulated within the microsphere rather than inserted on the surface of the microsphere. Ropivacaine was found to be buried deeper in the 1-PCL microsphere than in the 4-PCL microsphere. In vitro release assay revealed that small crystalline grains interfered with ropivacaine release in 4-PCL microspheres during the initial release period, but then two kinds of microspheres showed a similar ropivacaine release rate. We basically proved that the architecture of PCL has a negligible effect on ropivacaine release. Cell proliferation test revealed that the release of products from the microspheres resulted in insignificant toxicity towards mammalian cells.

Development of a dissolution method based on lipase for preclinical level A IVIVC of oral poly(ε-caprolactone) microspheres

Level A in vitro/in vivo correlation (IVIVC) of poly (ε-caprolactone) (PCL) microspheres for oral administration is challenging since in vitro PCL dissolution takes longer. The aims of this study were: 1) to develop three compositionally equivalent formulations of PCL microspheres with a different release rate of 6-methylcoumarin (6 MC), a drug candidate class IIc according to biopharmaceutical classification systems. 2) To develop a dissolution test for 6 MC-loaded PCL microspheres for oral administration. 3) To evaluate the influence of the PCL microspheres on the pharmacokinetic parameters of 6 MC and 4) to investigate a possible level A IVIVC of the 6 MC-loaded PCL microspheres. 6 MC-loaded PCL microspheres with different release rate were prepared and its physicochemical properties were evaluated as well as its release profiles. The pharmacokinetic parameters of the microspheres were investigated in Wistar rats. As results, it was possible to develop three compositionally equivalent 6 MC-loaded PCL microspheres with different release rate. Microspheres significantly affect pharmacokinetic parameters of 6 MC and a level A IVIVC was achieved for 6 MC-loaded PCL microspheres by using a dissolution method that includes lipase in the release medium. Developed dissolution method was able to predict the in vivo performance of 6 MC-loaded PCL microspheres in the investigated animal model.

Poly (ε-caprolactone) Microsphere Decorated with Nano-ZnO Based Phytoformulation: A Promising Antimicrobial Agent

In this study, an ethnonanocomposite was produced by using Curcuma zedoaria and ZnO nanoparticles. This was immobilised on poly (e-caprolactone) (PCL) microspheres for effective delivery. The presence of curcuminoids in C. zedoaria extract was confirmed by GC–MS and LC–MS analyses. The ZnO/C. zedoaria. nanocomposite synthesised in this study was subjected to X-ray diffraction and field emission scanning electron microscopy, which revealed the crystalline nature of formed nanocomposite. The nanocomposite was then immobilised on PCL microspheres by emulsion solvent evaporation. Further, XRD and FE-SEM confirmed the presence of nanocomposites and the spherical nature of the polymeric microspheres with diameter ranging from 4 to 36 µm. The antimicrobial activity analysis revealed the remarkable effectiveness of the nanocomposite loaded microspheres. The ethnonanocomposite loaded PCL microspheres generated in the study can thus be an effective antimicrobial agent with diverse biomedical applications.

Poly (ε-caprolactone) microspheres for prolonged release of selenium nanoparticles

Poly (ε-caprolactone) (PCL) microspheres as a carrier for sustained release of antibacterial agent, selenium nanoparticles (SeNPs), were developed. The obtained PCL/SeNPs microspheres were in the range 1–4 μm with the encapsulation efficiency of about 90%. The degradation process and release behavior of SeNPs from PCL microspheres were investigated in five different degradation media: phosphate buffer solution (PBS), a solution of lipase isolated from the porcine pancreas in PBS, 0.1 M hydrochloric acid (HCl), Pseudomonas aeruginosa PAO1 cell-free extract in PBS and implant fluid (exudate) from the subcutaneously implanted sterile polyvinyl sponges which induce a foreign-body inflammatory reaction. The samples were thoroughly characterized by SEM, TEM, FTIR, XRD, PSA, DSC, confocal microscopy, and ICP-OES techniques. Under physiological conditions at neutral pH, a very slow release of SeNPs occurred (3 and 8% in the case of PBS or PBS + lipase, respectively and after 660 days), while in the acidic environment their presence was not detected. On the other hand, the release in the medium with bacterial extract was much more pronounced, even after 24 h (13%). After 7 days, the concentration of SeNPs reached a maximum of around 30%. Also, 37% of SeNPs have been released after 11 days of incubation of PCL/SeNPs in the implant exudate. These results suggest that the release of SeNPs from PCL was triggered by Pseudomonas aeruginosa PAO1 bacterium as well as by foreign body inflammatory reaction to implant. Furthermore, PCL/SeNPs microspheres were investigated in terms of their biocompatibility. For this purpose, cytotoxicity, the formation of reactive oxygen species (ROS), and genotoxicity were evaluated on HepG2 cell line. The interaction of PCL/SeNPs with phagocytic cell line (Raw 264.7 macrophages) was monitored as well. It was found that the microspheres in investigated concentration range had no acute cytotoxic effects. Finally, SeNPs, as well as PCL/SeNPs, showed a considerable antibacterial activity against Gram-positive bacteria: Staphylococcus aureus (ATCC 25923) and Staphylococcus epidermidis (ATCC 1228). These results suggest that PCL/SeNPs-based system could be an attractive platform for a prolonged prevention of infections accompanying implants.

Formulation and in vitro characterization of rifampicin-loaded porous poly (ε-caprolactone) microspheres for sustained skeletal delivery.

PurposeMycobacterium tuberculosis is a serious public health problem affecting hundreds of millions of elderly people worldwide, which is difficult to be treated by traditional methods because of the peculiarity of skeletal system and liver damage caused by high-dose administration. In this research, a porous drug release system has been attempted to encapsulate rifampicin (RIF) into poly (ε-caprolactone) (PCL) microspheres to improve the efficacy and benefit of anti-tuberculosis drug in skeletal system.Materials and methodsThe microspheres prepared by two different methods, oil-in-oil (o/o) emulsion solvent evaporation method and oil-in-water (o/w) method, were characterized in terms of morphology, size, encapsulation efficiency, drug distribution, degradation, and crystallinity.ResultsThe microspheres exhibited a porous structure with evenly drug distribution prepared by o/o emulsion solvent evaporation method, and their diameter ranged from 50.54 to 57.34 μm. The encapsulation efficiency was up to 61.86% when drug-loading content was only 1.51%, and showed a little decrease with the drug-loading content increasing. In vitro release studies revealed that the drug release from porous microspheres was controlled by non-Fickian diffusion, and almost 80% of the RIF were completely released after 10 days. The results of RIF-loaded microspheres on the antibacterial activity against Staphylococcus aureus proved that the porous microspheres had strong antibacterial ability. In addition, the polymer crystallinity had prominent influence on the degradation rate of microspheres regardless of the morphology.ConclusionIt was an efficient way to entrap slightly water-soluble drug like RIF into PCL by o/o emulsion solvent evaporation method with uniform drug distribution. The RIF-loaded porous PCL microspheres showed the combination of good antimicrobial properties and excellent cytocompatibility, and it could generate gentle environment by PCL slow degradation.

Controlled drug release carriers based on PCL/PEO/PCL block copolymers

ABSTRACTIn order to create a new drug delivery system, the ibuprofen-loaded triblock copolymer PCL/PEO/PCL (PCEC) microspheres with a low PEO content (<2 wt%) were prepared by oil in water (o/w) solvent evaporation technique. The influence of PEO content, molecular weight of a polymer matrix and drug loading on the ibuprofen release profiles were evaluated. The interactions between polymer matrix and ibuprofen were detected by FTIR analysis. The presence of hydrophilic PEO segment in PCL chains caused the decrease in particle size, which further had a great impact on the drug release kinetics, i.e., initially faster release and significantly higher quantity of released drug compared to neat PCL. Ibuprofen release behavior from polymer matrix was governed by a diffusion process. In vitro cytotoxicity tests revealed that empty PCL and PCEC microspheres were not toxic at low concentrations, while ibuprofen-loaded microspheres exhibited cytotoxicity correlated with amounts of incorporated drug.

Accelerated full-thickness wound healing via sustained bFGF delivery based on a PVA/chitosan/gelatin hydrogel incorporating PCL microspheres

Herein, a hybrid hydrogel/microsphere system is introduced for accelerated wound healing by sustained release of basic fibroblast growth factor (bFGF). The hydrogel is composed of a mixture of PVA, gelatin and chitosan. The double-emulsion-solvent-evaporation method was utilized to obtain microspheres composed of PCL, as the organic phase, and PVA, as the aqueous phase. Subsequently, various in-vitro and in-vivo assays were performed to characterize the system. BSA was used to optimize the release mechanism, and encapsulation efficiency in microspheres, where a combination of 3% (w/v) PCL and 1% (w/v) PVA was found to be the optimum microsphere sample. Incorporation of microspheres within the hydrogel substrate also led to a zero-order release kinetics. Results from SEM images, also represented an average porosity of 54%, and average mean pore size of 35 ± 7 μm for the hydrogel system, and the diameter of 5 ± 2 μm for the microspheres. Moreover, in vivo study including wound healing process, and histological analysis regarding re-epithelization, angiogenesis, inflammation, fibroblast genesis and collagen formation were performed using Hematoxyline-Eosin (H&E) staining, Periodic Acid–Schiff (PAS) staining and Masson’s Trichrome staining. In-vivo results represented that sustained delivery of bFGF promoted by biocompatibility of PVA/chitosan/gelatin hydrogel, significantly contribute to accelerated wound healing.

The influence of hydrophilic mPEG segment on formation, morphology, and properties of PCL‐mPEG microspheres

AbstractThis research displayed the differences of formation process, morphology, degradation, and release behaviors between PCL and PCL‐mPEG microspheres. Lysozyme loaded microspheres were prepared by double emulsion evaporation method, and the double droplets transformation process was observed and compared under microscope. Microspheres morphology, in vitro degradation and release behaviors were evaluated by scanning electron microscope, gel permeation chromatography, and bicinchoninic acid protein assay kit. PCL‐mPEG microspheres got a rough surface and the outer water phase penetrated into PCL‐mPEG double droplet easier than PCL during the transformation, accompanied with a high broken percentage and size swelling. PCL‐mPEG microspheres get a faster degradation/erosion rate than PCL microspheres, and the rate was in direct proportion to mPEG chain length. In vitro release analysis showed that PCL‐mPEG microspheres get a faster release rate than PCL microspheres, and the rate was also in direct proportion to mPEG chain length.