Dual Drug Release Electrospun Core-Shell Nanofibers with Tunable Dose in the Second Phase

This study reports a new type of drug-loaded core-shell nanofibers capable of providing dual controlled release with tunable dose in the second phase. The core-shell nanofibers were fabricated through a modified coaxial electrospinning using a Teflon-coated concentric spinneret. Poly(vinyl pyrrolidone) and ethyl cellulose were used as the shell and core polymer matrices respectively, and the content of active ingredient acetaminophen (APAP) in the core was programmed. The Teflon-coated concentric spinneret may facilitate the efficacious and stable preparation of core-shell nanofibers through the modified coaxial electrospinning, where the core fluids were electrospinnable and the shell fluid had no electrospinnability. The resultant nanofibers had linear morphologies and clear core-shell structures, as observed by the scanning and transmission electron microscopic images. APAP was amorphously distributed in the shell and core polymer matrices due to the favorite second-order interactions, as indicated by the X-ray diffraction and FTIR spectroscopic tests. The results from the in vitro dissolution tests demonstrated that the core-shell nanofibers were able to furnish the desired dual drug controlled-release profiles with a tunable drug release amount in the second phase. The modified coaxial electrospinning is a useful tool to generate nanostructures with a tailored components and compositions in their different parts, and thus to realize the desired functional performances.     

Using poly[2-methoxy-5-(2′-ethyl-hexyloxy)-1,4-phenylene vinylene] as shell to fabricate the highly fluorescent nanofibers by coaxial electrospinning

Poly[2-methoxy-5-(2′-ethyl-hexyloxy)-1,4-phenylene vinylene] (MEH-PPV) is an excellent conjugated polymer and broadly used in the polymer photoelectron devices, but difficult to be electronspun directly. In the present study, the core-shell structured nanofibers were fabricated by coaxial electrospinning MEH-PPV (shell) in chlorobenzene and PVP (core) in 1,2-dichloroethane. MEH-PPV was soluble in the above two solvents, which prevented the precipitation of MEH-PPV and enhanced the adhering action between the two polymers in coaxial electrospinning process. We anticipate that these uniform core/shell PVP/MEH-PPV nanofibers with highly fluorescent property will have potential applications in the fabrication of polymer nano-photoelectron devices.     

Dual-functioning core@shell nanofiber strip for enhancing drinking water quality: Polysulfone/graphene oxide adsorbent core layer and polyvinylpyrrolidone/mint sacrificial shell layer

Drinking water quality is considered a continuing concern of human health. Herein, for the improvement of water quality, dual functioning core-shell (CS) nanofibers were developed by use of polysulfone (PSU)/graphene oxide (GO) as the adsorbent core layer for removing heavy metal ions and polyvinylpyrrolidone (PVP)/mint extract as the shell layer for inducing antioxidant activity to the water. Various analyses on the strip samples before and after the water treatment experiment were performed. ATR-FTIR by appearing or disappearing chemical bonds, TEM micrographs based on the formation of shell layer around the nanofibers, FESEM according to the uniformity and diameter of nanofibers, and EDX analysis based on the elemental and mapping results, verified the core-shell structure of nanofibers. The results of the antioxidant activity demonstrated that after the dissolution shell layer, radical scavenging capability of water was improved effectively. Thereafter, the remained core layer had a high capacity and efficiency for the adsorption of metal ions especially for CS3 with 70.9% and 58.7% efficiency for Fe(III) and Ni(II). By achieving 0.975 and 0.568 L/g partition coefficient (PC), the desired performance of CS3 (core layer: 15 wt% PSU, 0.5% GO and shell layer: 5 wt% PVP, and 2.5 wt% mint) was confirmed.     

Flurbiprofen axetil loaded coaxial electrospun poly(vinyl pyrrolidone)–nanopoly(lactic‐co‐glycolic acid) core–shell composite nanofibers: Preparation,characterization, and anti‐adhesion activity

Flurbiprofen axetil (FA)‐loaded coaxial electrospun poly(vinyl pyrrolidone) (PVP)–nanopoly(lactic‐co‐glycolic acid) core–shell composite nanofibers were successfully fabricated by a facile coaxial electrospinning, and an electrospun drug‐loaded system was formed for anti‐adhesion applications. The FA, which is a kind of lipid microsphere nonsteroidal anti‐inflammatory drug, was shown to be successfully adsorbed in the PVP, and the formed poly(lactic‐co‐glycolic acid) (PLGA)/PVP/FA composite nanofibers exhibited a uniform and smooth morphology. The cell viability assay and cell morphology observation revealed that the formed PLGA/PVP/FA composite nanofibers were cytocompatible. Importantly, the loaded FA within the PLGA/PVP coaxial nanofibers showed a sustained‐release profile and anti‐adhesion activity to inhibit the growth of the IEC‐6 and NIH3T3 model cells. With the significantly reduced burst‐release profile, good cytocompatibility, and anti‐adhesion activity, the developed PLGA/PVP/FA composite nanofibers were proposed to be a promising material in the fields of tissue engineering and pharmaceutical science. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41982.     

具有梯级释药性能的核壳型双重载药微球

分别利用单轴和同轴静电喷雾法成功制备出以聚乳酸-羟基乙酸共聚物（PLGA）为内核基质、聚乙烯吡咯烷酮（PVP）为外壳基质的核壳型双重载药微球,其中,抗菌药物盐酸万古霉素（VA）被包封于微球外壳,促成骨药物地塞米松（DA）被负载于微球内核。对载药微球的形貌结构、物理性质和体外释药性能进行了表征和分析。结果表明,当电喷前体PVP浓度为80g/L时,单轴和同轴静电喷雾方法均可得到大小均一、球形良好的核壳型微球。X射线衍射（XRD）和差示扫描量热（DSC）结果表明,DA晶体被成功包封于核壳型微球后转变为无定形状态。基于PVP的水溶性和PLGA的缓慢降解特性,两种核壳型载药微球都实现了壳层VA快速释放、内核DA缓慢释放的梯级释药性能。本文制备得到的具有梯级释药性能的核壳型载药微球在药物控释、组织工程等领域有很好的应用前景。     

Influence of structure on release profile of acyclovir loaded polyurethane nanofibers: Monolithic and core/shell structures

In this study, monolithic and core/shell polyurethane (PU) nanofibers were fabricated by single and coaxial electrospinning techniques, respectively. An antivirus drug, Acyclovir (ACY), was loaded on PU nanofibers. The physical condition and interaction of the loaded ACY within these nanofibers were studied by FTIR, XRD, DSC, SEM, and TEM. In vitro tests exhibited an obvious difference in the release pattern between monolithic and core/shell nanofibers and burst release in monolithic nanofibers could be controlled by core/shell structure. Release profile was found to follow Korsmeyere‐Peppas model with Fickian diffusion mechanism. Our study demonstrated that the ACY‐loaded core/shell nanofibers might serve as a device for drug delivery systems. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 44073.     

Electrospun biocompatible poly (ε-caprolactonediol)-based polyurethane core/shell nanofibrous scaffold for controlled release of temozolomide

The electrospun biocompatible poly (ε-caprolactonediol)-based polyurethane (PCL-Diol-b-PU) core/shell nanofibrous scaffolds were prepared via the coaxial electrospinning process. Temozolomide (TMZ) as an anticancer drug was loaded into the core of fibers to control the release of TMZ for the treatment of glioblastoma. The properties of nanofibers were characterized using XRD, FTIR, SEM, and TEM analysis. The sustained delivery of TMZ without initial burst release was achieved from all prepared core–shell nanofibrous samples over 30 days. The cytotoxicity results revealed that the TMZ-loaded PCL-Diol-b-PU core–shell nanofibers could be used as a drug delivery implant to deliver TMZ against glioblastoma tumors.     

Fast Disintegrating Quercetin-Loaded Drug Delivery Systems Fabricated Using Coaxial Electrospinning

The objective of this study is to develop a structural nanocomposite of multiple components in the form of core-sheath nanofibres using coaxial electrospinning for the fast dissolving of a poorly water-soluble drug quercetin. Under the selected conditions, core-sheath nanofibres with quercetin and sodium dodecyl sulphate (SDS) distributed in the core and sheath part of nanofibres, respectively, were successfully generated, and the drug content in the nanofibres was able to be controlled simply through manipulating the core fluid flow rates. Field emission scanning electron microscope (FESEM) images demonstrated that the nanofibres prepared from the single sheath fluid and double core/sheath fluids (with core-to-sheath flow rate ratios of 0.4 and 0.7) have linear morphology with a uniform structure and smooth surface. The TEM images clearly demonstrated the core-sheath structures of the produced nanocomposites. Differential scanning calorimetry (DSC) and X-ray diffraction (XRD) results verified that quercetin and SDS were well distributed in the polyvinylpyrrolidone (PVP) matrix in an amorphous state, due to the favourite second-order interactions. In vitro dissolution studies showed that the core-sheath composite nanofibre mats could disintegrate rapidly to release quercetin within 1 min. The study reported here provides an example of the systematic design, preparation, characterization and application of a new type of structural nanocomposite as a fast-disintegrating drug delivery system.     

负载活性组分的核壳结构纤维膜的制备及性能

采用同轴静电纺丝技术将蛛丝蛋白（Ss）和美洲大蠊提取物（PAE）分别负载于纳米纤维的壳层与核层。随着Ss的增加,纤维直径从350 nm降至280 nm,核层直径由120nm升至140 nm,壳层厚度由115 nm降至70 nm。Ss的加入使纳米纤维膜具有良好的机械性能和亲水性,纳米纤维膜的拉伸强度可达到4.31 MPa,溶胀率可达到150%,水蒸气透过率可达到1834 g/(m2?24h),水接触角减小到 32.7 ?。纳米纤维膜核壳结构能够有效抑制药物突释,实现药物长效释放,7天内药物释放可达77%;纳米纤维膜能够有效抑制细菌生长,促进细胞增殖,相较于未负载Ss的纳米纤维膜,负载20%Ss的纤维膜的细胞增殖效果提高25%,说明Ss和PAE在伤口愈合过程中能够起到协同作用。     

Bicomponent nanofibers from core–shell nozzle in gas jet spinning process

This work evaluates the use of a core–shell nozzle assembly in conjunction with gas jet spinning technique for production of bicomponent nanofibers from an immiscible polymer pair of polyvinylpyrrolidone (PVP) and poly(vinyl acetate) (PVAc) with three morphological forms—interpenetrating network (IPN), core–shell, and bilobal structurers—by varying the sets of miscible solvents offering different affinity for the polymers. Such fiber structures have strong potential in drug delivery and wound dressing applications. Solutions of PVP and PVAc in respective single solvents metered through a core–shell nozzle assembly meet at the exit of the nozzle and a liquid jet is initiated upon contact with a turbulent gas jet. The gas jet stretches the liquid jet into nanofibers. The results indicate that miscible solvent pairs with low affinity for one of the polymer component yield core–shell morphology with distinct polymer interfaces, while the miscible solvent pairs with high affinity for both polymers produce IPN morphology. Also, interchanging core and shell solutions does not alter the IPN morphology. Finally, bilobal nanofiber structures result from spinning of polymer solutions in miscible solvents with low affinity for the second polymer using a nonconcentric core–shell nozzle assembly. © 2020 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48901.     

Dual drug release from CO2‐infused nanofibers via hydrophobic and hydrophilic interactions

This study investigated the effects of hydrophobic–hydrophilic interactions on dual drug release from CO₂‐infused nanofibers scaffolds (PCL, PCL–gelatin, and PCL “core” PCL–gelatin “shell”) using BODIPY 493/503 and Rhodamine B fluorescent dyes as drug models. Favorable dye–scaffold interactions increased total dye loading and promoted steady, more linear release. Unfavorable dye–scaffold interactions reduced overall loading and led to a greater burst release of dye. However, when CO₂ was used to infuse dye into an unfavorable scaffold, the changes in loading and release were less pronounced. When two dyes were infused, these behaviors were accentuated due to interactions between the dissolved forms of the dyes. Core–shell composite nanofibers displayed radically different release properties versus pure PCL–gelatin fibers when treated with dyes via CO₂ infusion. Dye release from core–shell scaffolds was highly sensitive to both interactions with scaffolds and the phase of CO₂ used to infuse the compounds of interest. By using different phases of CO₂ to partition dyes into hydrophobic and hydrophilic sections of core–shell nanofibers, such interactions can be manipulated to develop a bimodal drug release system with potential application in drug delivery or tissue engineering. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42571.     

Synthesis and Gas Sensing Properties of TiO2–ZnO Core-Shell Nanofibers

We fabricated TiO₂–ZnO core-shell nanofibers via a novel two-step process. In the first step, the TiO₂ core nanofibers were synthesized by electrospinning. Subsequently, the ZnO shell layers were grown in a controlled manner using atomic layer deposition. The methodology proposed in this work is expected to be one of most suitable methods for preparing various kinds of oxide core-shell nanofibers or nanowires. We investigated the O₂ sensing properties of the synthesized core-shell nanofibers. Good sensitivity and dynamic repeatability were observed for the sensor, demonstrating that the core-shell nanofibers hold promise for the realization of sensitive and reliable chemical sensors.     

Electrospun core–shell nanofibers for drug encapsulation and sustained release

Fabrication of core–shell nanofibers by coaxial electrospinning system suited for drug delivery applications was investigated based on tetracycline hydrochloride (TCH) as the core and poly(lactide‐co‐glycolide) as the shell materials. Comparison of drug release from monolithic fibers (blend electrospinning) and core–shell structures was performed to evaluate the efficacy of the core–shell morphology. The nanofibrous webs are potentially interesting for wound healing purposes since they can be maintained for an adequate length of time to gradually disinfect a local area without the need of bandage renewal. Further, our studies showed the potential of core–shell nanostructures for sustained drug release, which also suppressed the burst release effect from 62 to 44% in the first 3 hours by adding only 1 wt% TCH to the polymeric shell. POLYM. ENG. SCI., 2013. © 2013 Society of Plastics Engineers     

Core-shell nanohydrogel structures as tunable delivery systems

Poly(acrylonitrile-co-N-isopropylacrylamide) (p(AN-co-NIPAM)) core-shell hydrogel nanoparticles were synthesized by microemulsion polymerization and their feasibility as a drug carrier was investigated. Highly monodispersed nanoparticles with desired size range - i.e., 50-150 nm - were prepared by adjusting the reaction conditions. The hydrophobic core of the composite which consists primarily of poly(acrylonitrile), can be easily made highly hydrophilic by converting the nitrile groups to the corresponding amidoxime groups. This provides a level of tunability in the hydrophobicity/hydrophilicity balance of the composite nanoparticle. The thermo-responsive feature of the shell was utilized for the release of a model drug, propranolol (PPL). It is shown that the loading/release capacity of nanoparticles was increased almost two-fold by the amidoximation of the core material.     

Engineering oligo(ethylene glycol)-based thermosensitive microgels for drug delivery applications

Novel oligo(ethylene glycol)-based thermosensitive microgels with well engineered core-shell structures were developed for storage and delivery of chemotherapeutic agents. The core is consisted of hydrophobic poly[2-(2-methoxyethoxy)ethyl methacrylate], while the shell is consisted of hydrophilic copolymer of 2-(2-methoxyethoxy)ethyl methacrylate with oligo(ethylene glycol) methyl ether methacrylates. These core-shell microgels exhibit tunable volume phase transition temperature and excellent colloidal stability across the physiologically important temperature range. The thickness of the hydrophilic shell can control the collapsing degree (or mesh size) of the hydrophobic core network, which can be utilized to significantly increase the loading capacity of the model hydrophobic drugs dipyridamole by tailoring the shell thickness of microgels. While the microgels are nontoxic, the drug molecules released from the microgels remain active to kill the cancer cells. The presented results provide important guidelines for the rational design of core-shell structured polymeric microgels for drug uptake and release applications.     

Thermosensitive poly(N-isopropylacrylamide) nanocapsules with controlled permeability

In this paper, novel thermosensitive poly(N-isopropylacrylamide) (PNIPAM) nanocapsules with temperature-tunable diameter and permeability are reported. Firstly, the core-shell composite microparticles were synthesized by precipitation polymerization with isothiocyanate fluorescein (FITC) entrapped SiO₂ as core and cross-linked PNIPAM as shell. Then, the SiO₂ core was etched by hydrofluoric acid at certain condition and the pre-trapped FITC molecules remained within the inner cavity. The FITC release profile and TEM studies clearly indicate that the release behavior of FITC could be controlled effectively by the external temperature. Above the LCST of PNIPAM (32 °C), the dehydrated PNIPAM shell inhibited the release of FITC from the internal cavity while below its LCST, the fluorophore could permeate the swollen shell easily.     

基于静电纺丝技术的PLGA载药纳米纤维膜的制备工艺

同轴静电纺丝法制备的聚乳酸-乙醇酸(PLGA)纳米纤维具有良好的生物相容性和生物可降解性, 加之其高孔隙率和高透氧率, 使其能成为优良的药物载体。本文初步摸索了PLGA的同轴静电纺丝的工艺条件, 并通过同轴静电纺丝法制备了PLGA载氟比洛芬酯(FA)的纳米纤维膜, 应用扫描电子显微镜、红外光谱分析观察纤维的表观形貌并确定其微观结构。重点探究了不同溶剂配比的混合溶剂对载药纤维膜药物释放性能影响。研究结果表明在U⁺为+15.00kV, U^-为-2.50kV, 接受距离为15cm, 壳层推进速度为0.4mm/min, 芯层推进速度为0.1mm/min进行静电纺丝时, 所制备的PLGA(壳)/PVP+FA(核)复合载药纤维膜壳核结构良好, 且成功载了约0.5%的FA。当改变壳层混合溶剂(DCM和DMF)和芯层混合溶剂(无水乙醇和DMF)体积比时, 纤维直径会随着DMF的减少而增大。     

Synthesis and characterization of cross-linked poly(acrylic acid)-poly(styrene-alt-maleic anhydride) core-shell microcapsule absorbents for cement mortar

We synthesized core-shell microcapsule absorbents with cPAA (cross-linked poly(acrylic acid)) as the core and PSMA (poly(styrene-alt-maleic anhydride)) as the shell by precipitation polymerization, where the shell served to delay the absorption of excess water in cement mortars. To control shell thickness, the cPAA-PSMA capsules were synthesized with core monomer mass to shell monomer mass ratios of 1/0.5, 1/1, and 1/1.5. We observed the hydrolysis of the PSMA polymer in a cement-saturated aqueous solution by Fourier transform infrared (FT-IR) spectroscopy. Furthermore, core-shell structures were observed for 1/1 (cPAA-PSMA #3) and 1/1.5 (cPAA-PSMA #4) core/shell monomer mass ratios, whereas no core-shell structures were observed for the 1/0.5 (cPAA-PSMA #2) microcapsules by transmission electron microscopy (TEM).     

紫杉醇两亲性共聚物纳米胶束体外释药动力学

采用低分子量PEG-PCL-PEG、mPEG-PLLA、mPEG-PDLLA等两亲性嵌段共聚物作载体包载紫杉醇形成纳米胶束.研究了不同载药率胶束在磷酸缓冲液中释放的动力学,发现紫杉醇PEG-PCL-PEG胶束和mPEG-PLLA胶束的体外释药遵从一级释放动力学;紫杉醇mPEG-PDLLA纳米胶束的体外释放多呈现出两段零级释放动力学;低载药率胶束表现出高释药率;体外释药过程中磷酸缓冲液的更新量越大,紫杉醇的释放率越高.     

Preparation of core-shell emulsion polymer and optimization of shell composition with respect to opacity of paint film

A series of core-shell latexes comprising a poly(n-butyl acrylate-co-methyl methacrylate-co-methacrylic acid) (PBA/MMA/MAA) core and a poly(styrene-co-acrylonitrile) (PS/AN), poly(butyl acrylate-co-methyl methacrylate) (PBA/MMA) shell were prepared at different shell composition ratios. These core-shell binders were used for preparation of decorative coatings. The latexes were synthesized by a semi-continuous sequential emulsion polymerization and characterized by using transmission electron microscopy (TEM), particle size analyser, viscometry and opacity of paint film. The core-shell emulsion with styrene/acrylonitrile ratio 60/40 as shell composition shows the best optical properties.