Coaxial Process Research Articles

Synergistic Effects of Radical Distributions of Soluble and Insoluble Polymers within Electrospun Nanofibers for an Extending Release of Ferulic Acid.

Polymeric composites for manipulating the sustained release of an encapsulated active ingredient are highly sought after for many practical applications; particularly, water-insoluble polymers and core-shell structures are frequently explored to manipulate the release behaviors of drug molecules over an extended time period. In this study, electrospun core-shell nanostructures were utilized to develop a brand-new strategy to tailor the spatial distributions of both an insoluble polymer (ethylcellulose, EC) and soluble polymer (polyvinylpyrrolidone, PVP) within the nanofibers, thereby manipulating the extended-release behaviors of the loaded active ingredient, ferulic acid (FA). Scanning electron microscopy and transmission electron microscopy assessments revealed that all the prepared nanofibers had a linear morphology without beads or spindles, and those from the coaxial processes had an obvious core-shell structure. X-ray diffraction and attenuated total reflectance Fourier transform infrared spectroscopic tests confirmed that FA had fine compatibility with EC and PVP, and presented in all the nanofibers in an amorphous state. In vitro dissolution tests indicated that the radical distributions of EC (decreasing from shell to core) and PVP (increasing from shell to core) were able to play their important role in manipulating the release behaviors of FA elaborately. On one hand, the core-shell nanofibers F3 had the advantages of homogeneous composite nanofibers F1 with a higher content of EC prepared from the shell solutions to inhibit the initial burst release and provide a longer time period of sustained release. On the other hand, F3 had the advantages of nanofibers F2 with a higher content of PVP prepared from the core solutions to inhibit the negative tailing-off release. The key element was the water permeation rates, controlled by the ratios of soluble and insoluble polymers. The new strategy based on core-shell structure paves a way for developing a wide variety of polymeric composites with heterogeneous distributions for realizing the desired functional performances.

Electrospun Fenoprofen/Polycaprolactone @ Tranexamic Acid/Hydroxyapatite Nanofibers as Orthopedic Hemostasis Dressings.

Dressings with multiple functional performances (such as hemostasis, promoting regeneration, analgesia, and anti-inflammatory effects) are highly desired in orthopedic surgery. Herein, several new kinds of medicated nanofibers loaded with several active ingredients for providing multiple functions were prepared using the modified coaxial electrospinning processes. With an electrospinnable solution composed of polycaprolactone and fenoprofen as the core working fluid, several different types of unspinnable fluids (including pure solvent, nanosuspension containing tranexamic acid and hydroxyapatite, and dilute polymeric solution comprising tranexamic acid, hydroxyapatite, and polyvinylpyrrolidone) were explored to implement the modified coaxial processes for creating the multifunctional nanofibers. Their morphologies and inner structures were assessed through scanning and transmission electron microscopes, which all showed a linear format without the discerned beads or spindles and a diameter smaller than 1.0 μm, and some of them had incomplete core-shell nanostructures, represented by the symbol @. Additionally, strange details about the sheaths' topographies were observed, which included cracks, adhesions, and embedded nanoparticles. XRD and FTIR verified that the drugs tranexamic acid and fenoprofen presented in the nanofibers in an amorphous state, which resulted from the fine compatibility among the involved components. All the prepared samples were demonstrated to have a fine hydrophilic property and exhibited a lower water contact angle smaller than 40° in 300 ms. In vitro dissolution tests indicated that fenoprofen was released in a sustained manner over 6 h through a typical Fickian diffusion mechanism. Hemostatic tests verified that the intentional distribution of tranexamic acid on the shell sections was able to endow a rapid hemostatic effect within 60 s.

Tri-Layer Core-Shell Fibers from Coaxial Electrospinning for a Modified Release of Metronidazole.

Polymers are the backbone of drug delivery. Electrospinning has greatly enriched the strategies that have been explored for developing novel drug delivery systems using polymers during the past two decades. In this study, four different kinds of polymers, i.e., the water-soluble polymer poly (vinyl alcohol) (PVA), the insoluble polymer poly(ε-caprolactone) (PCL), the insoluble polymer Eudragit RL100 (ERL100) and the pH-sensitive polymer Eudragit S100 (ES100) were successfully converted into types of tri-layer tri-polymer core-shell fibers through bi-fluid coaxial electrospinning. During the coaxial process, the model drug metronidazole (MTD) was loaded into the shell working fluid, which was an emulsion. The micro-formation mechanism of the tri-layer core-shell fibers from the coaxial emulsion electrospinning was proposed. Scanning electron microscope and transmission electron microscope evaluations verified the linear morphology of the resultant fibers and their obvious tri-layer multiple-chamber structures. X-ray diffraction and Fourier transform infrared spectroscopy measurements demonstrated that the drug MTD presented in the fibers in an amorphous state and was compatible with the three polymeric matrices. In vitro dissolution tests verified that the three kinds of polymer could act in a synergistic manner for a prolonged sustained-release profile of MTD in the gut. The drug controlled-release mechanisms were suggested in detail. The protocols reported here pioneer a new route for creating a tri-layer core-shell structure from both aqueous and organic solvents, and a new strategy for developing advanced drug delivery systems with sophisticated drug controlled-release profiles.

Simulation Analysis and Optimization Design of Electromagnetic Fields in Coaxial Processing Cavities Based on the Theory of Electrostatic Fields

The coaxial processing cavity is an important component of high-frequency electromagnetic water treatment devices. Due to its easy installation, wide applicability, and excellent scale removal effect, it has been widely used in various factories. To study the influence of excitation source waveform, processing cavity length, and anode-cathode radius ratio on the intensity and distribution of the electromagnetic field in the coaxial processing cavity under time-varying fields, this paper derives the numerical calculation formula for electromagnetic energy in the coaxial processing cavity based on the theory of electrostatic fields. The finite element method is used to visualize the intensity and distribution of the electromagnetic field in the coaxial processing cavity. By optimizing the structure of the coaxial processing cavity, the optimal range of the anode-cathode radius ratio is determined. The research results show that, under the conditions of electrostatic field theory, square waves have the maximum electromagnetic energy, the length of the processing cavity does not affect the distribution of the electromagnetic field, and the optimal anode-cathode radius ratio range is 0.375-0.5.

Electrospun self-emulsifying core-shell nanofibers for effective delivery of paclitaxel.

The poor solubility of numerous drugs pose a long-existing challenge to the researchers in the fields of pharmaceutics, bioengineering and biotechnology. Many "top-down" and "bottom-up" nano fabrication methods have been exploited to provide solutions for this issue. In this study, a combination strategy of top-down process (electrospinning) and bottom-up (self-emulsifying) was demonstrated to be useful for enhancing the dissolution of a typical poorly water-soluble anticancer model drug (paclitaxel, PTX). With polyvinylpyrrolidone (PVP K90) as the filament-forming matrix and drug carrier, polyoxyethylene castor oil (PCO) as emulsifier, and triglyceride (TG) as oil phase, Both a single-fluid blending process and a coaxial process were utilized to prepare medicated nanofibers. Scanning electron microscope and transmission electron microscope (TEM) results clearly demonstrated the morphology and inner structures of the nanofibers. The lipid nanoparticles of emulsions after self-emulsification were also assessed through TEM. The encapsulation efficiency (EE) and in vitro dissolution tests demonstrated that the cores-shell nanofibers could provide a better self-emulsifying process int terms of a higher EE and a better drug sustained release profile. Meanwhile, an increase of sheath fluid rate could benefit an even better results, suggesting a clear process-property-performance relationship. The protocols reported here pave anew way for effective oral delivery of poorly water-soluble drug.

In situ quality monitoring in direct energy deposition process using co-axial process zone imaging and deep contrastive learning

Many strategic industrial sectors prefer Directed Energy Deposition (DED) to other Additive Manufacturing (AM) technologies due to the high material deposition and build rates. However, the inadvertent formation of defects such as porosity, micro-cracks and microstructure anomalies hinders its adoption in industries that require specific mechanical and microstructural properties. These defects are caused by undesirable fluctuations in process conditions such as material flow rate, laser power, melt pool dynamics, environment gas composition, temperature gradients. This research proposes in situ quality monitoring of DED using images of process zone and contrastive learning-based Convolutional Neural Network (CNN). Experiments included deposition of titanium powder (Cp-Ti, grade 1) with the particle size ranging between 45 and 106 μm on the base plate (99.6 % Ti6Al4V grade 1), forming a cube geometry. The process parameters were tuned to achieve six quality grades. The video of the process zone was recorded co-axially to the laser beam during the entire manufacturing, which was eventually used as the input to train CNN's based on contrastive losses. An in situ monitoring strategy for classifying the different quality grades was demonstrated in a supervised and semi-supervised manner, with an accuracy ranging between 89 % and 97 %. The performance of the developed framework was compared to an alternative clustering technique, namely t-distributed stochastic neighbour embedding, justifying the efficiency of our approach. The developed methodology demonstrates the possibility to track workpiece manufacturing quality using simple CCD cameras with minimum interventions on the commercial machines.

Empirical Model for the Description of Weld Seam Geometry in Coaxial Laser Hot-Wire Deposition Welding Processes with Different Steel Wires

Claddings are used to protect areas of components that are exposed to particular chemical, physical or tribological stresses. The aim when developing a cladding process is to achieve a cladding with low waviness in order to reduce the amount of machining required. Computational models and FEA simulations can be used to determine process parameters for claddings with low rework including a prediction of the height and width of a single weld seam aswell as the development of welding strategies. In this paper empirical models describing the geometry of single weld seams on a substrate manufactured with a coaxial laser hot-wire cladding process are investigated for three steel wire materials and different welding parameters. The coordinates of surface points of the weld seams were detected using a laser scanning microscope and post-processed by a self-created script. In order to describe the cross sectional shape of the weld seams, the parameters of parabolic, cosinusiodal or circular arc model functions are derived from the surface data using a fitting algorithm. For the tested wire materials, an effect of the wire material on the shape of the weld seam was not observed. The investigations also show that regardless of the varied welding parameter set or wire material, a circular model function appears to be the most suitable model shape for describing the cross sectional weld seam geometry in coaxial laser metal deposition with hot-wire. The regression residua using a circular arc model function ranged from 18.9 upmum to 34.6 upmum, which indicates a good approximation.

Electrosprayed Ultra-Thin Coating of Ethyl Cellulose on Drug Nanoparticles for Improved Sustained Release

In nanopharmaceutics, polymeric coating is a popular strategy for modifying the drug release kinetics and, thus, new methods for implementing the nanocoating processes are highly desired. In the present study, a modified coaxial electrospraying process was developed to formulate an ultra-thin layer of ethyl cellulose (EC) on a medicated composite core consisting of tamoxifen citrate (TAM) and EC. A traditional single-fluid blending electrospraying and its monolithic EC-TAM nanoparticles (NPs) were exploited to compare. The modified coaxial processes were demonstrated to be more continuous and robust. The created NPs with EC coating had a higher quality than the monolithic ones in terms of the shape, surface smoothness, and the uniform size distribution, as verified by the SEM and TEM results. XRD patterns suggested that TAM presented in all the NPs in an amorphous state thanks to the fine compatibility between EC and TAM, as indicated by the attenuated total reflection (ATR)-FTIR spectra. In vitro dissolution tests demonstrated that the NPs with EC coating required a time period of 7.58 h, 12.79 h, and 28.74 h for an accumulative release of 30%, 50%, and 90% of the loaded drug, respectively. The protocols reported here open a new way for developing novel medicated nanoparticles with functional coating.

Correlating in-situ process monitoring data with the reduction in load bearing capacity of selective laser melted Ti–6Al–4V porous biomaterials

Selective Laser Melting allows for the creation of intricate porous structures, that possess favourable biological properties. These structures are known as porous biomaterials. The focus of this paper is to evaluate the use of an in-line photodiode based process monitoring system, for the monitoring of the operational behaviour of the laser, and to correlate this with the resultant parts mechanical performance.In this study the production scale Renishaw 500M was used to produce porous structures, using Ti–6Al–4V feedstock powder. During the process, a co-axial process monitoring system was utilised to generate data relating to both the meltpool and the operational behaviour of the laser. An advanced scanning technique was used to produce the structures, whereby the laser parameters determine the strut dimensions. In this study, the laser input energy was reduced by 33%, 66% and 100%, at specific layers within the structures. Computer Tomography and Scanning Electron Microscopy was utilised to characterise the affected struts within the structures, while quasi-static compression testing was used to determine the structure's mechanical properties.It was demonstrated that as the level of input energy decreased and the number of affected layers increased, a corresponding decrease in the load bearing capacity of the structures occurred. With the structures experiencing a significant loss in strength also exhibiting a change in the failure mode during compression testing. Data generated during the processing of such structures was compared to the data generated during the processing of control structures, with the difference between the two been calculated on a layer-by-layer basis. A clear correlation was demonstrated between the total level of deviation between the two signal sets and a reduction in the load bearing capacity of the structures. This indicates that by comparing build data to a benchmark data set, valuable information relating to the structural integrity of the porous structures can be obtained.

The Relationships between Process Parameters and Polymeric Nanofibers Fabricated Using a Modified Coaxial Electrospinning.

The concrete relationship between the process parameters and nanoproduct properties is an important challenge for applying nanotechnology to produce functional nanomaterials. In this study, the relationships between series of process parameters and the medicated nanofibers’ diameter were investigated. With an electrospinnable solution of hydroxypropyl methylcellulose (HPMC) and ketoprofen as the core fluid, four kinds of nanofibers were prepared with ethanol as a sheath fluid and under the variable applied voltages. Based on these nanofibers, a series of relationships between the process parameters and the nanofibers’ diameters (D) were disclosed, such as with the height of the Taylor cone (H, D = 125 + 363H), with the angle of the Taylor cone (α, D = 1576 − 19α), with the length of the straight fluid jet (L, D = 285 + 209L), and with the spreading angle of the instable region (θ, D = 2342 − 43θ). In vitro dissolution tests verified that the smaller the diameters, the faster ketoprofen (KET) was released from the HPMC nanofibers. These concrete process-property relationships should provide a way to achieve new knowledge about the electrostatic energy-fluid interactions, and to meanwhile improve researchers’ capability to optimize the coaxial process conditions to achieve the desired nanoproducts.

Fast Dissolving of Ferulic Acid via Electrospun Ternary Amorphous Composites Produced by a Coaxial Process.

Enhancing the dissolution of insoluble active ingredients comprises one of the most important issues in the pharmaceutical and biomaterial fields. Here, a third generation solid dispersion (3rd SD) of ferulic acid was designed and fabricated by a modified coaxial electrospinning process. A traditional second generation SD (2nd SD) was also prepared by common one-fluid blending electrospinning and was used as a control. With poly(vinyl alcohol) as the fiber matrix and polyvinylpyrrolidone K10 as an additive in the 3rd SDs, the two electrospinning processes were investigated. The prepared 2nd and 3rd SDs were subjected to a series of characterizations, including X-ray diffraction (XRD), scanning electron microscope (SEM), hydrophilicity and in vitro drug dissolving experiments. The results demonstrate that both SDs were monolithic nanocomposites and that the drugs were amorphously distributed within the matrix. However, the 3rd SDs had better morphology with smaller size, narrower size distribution, and smaller water contact angles than the 2nd SDs. Dissolution tests verified that the 3rd SDs could release their loaded cargoes within 60 s, which was over three times faster than the 2nd SDs. Therefore, a combined strategy based on the modified coaxial electrospinning and the logical selections of drug carriers is demonstrated for creating advanced biomaterials.

Fast dissolving drug delivery membrane based on the ultra-thin shell of electrospun core-shell nanofibers

Structural nanocomposites that provide fast dissolving drug release profiles are highly in demand in pharmaceutics. In this study, a poorly water-soluble drug such as quercetin or tamoxifen citrate (TC) was selected as a model active pharmaceutical ingredient. Core-shell nanofibers with ultra-thin shells were designed and prepared using modified coaxial electrospinning. Polyvinylpyrrolidone (PVP) K90 or Polycaprolactone (PCL) was selected as core. The drugs and PVP K10 were selected as shell. All types of solutions can be used as the shell fluids in modified coaxial process regardless of their electrospinnability, which means the increasing functional ingredients and unspinnable matrix can be processed. Evaluations via SEM and TEM demonstrated that the core-shell nanofibers had linear morphology with a shell thickness smaller than 100 nm. XRD and FTIR results showed that the model drug was distributed in the polymeric matrix amorphously and that PVP K10 had good compatibility with quercetin or TC. In vitro dissolution tests suggested that the core-shell nanofibers with ultra-thin shells released the loaded cargoes in the dissolution media within 1 min. The present investigation paved a new way for implementing the modified coaxial processes, which can be utilized to fabricate structural nanocomposites with ultra-thin shells for enhancing the fast dissolution of poorly water-soluble drugs.

Colon-specific pulsatile drug release provided by electrospun shellac nanocoating on hydrophilic amorphous composites.

BackgroundColon-specific pulsatile drug release, as a combined drug controlled-release model, is a useful drug delivery manner for a series of diseases. New nanomedicines and related preparation methods are highly desired.MethodsWith diclofenac sodium (DS) as a model drug, a new type of structural nanocomposite (SC), in which composite polyvinylpyrrolidone (PVP)–DS core was coated by shellac, was fabricated via modified coaxial electrospinning. For comparison, traditional PVP–DS monolithic hydrophilic nanocomposites (HCs) were generated using a traditional blending process. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), attenuated total reflectance-Fourier transform infrared (ATR-FTIR), water contact angle (WCA), and in vitro dissolution and ex vivo permeation tests were conducted to characterize the composites.ResultsSEM images demonstrated that both composites were linear nanofibers with smooth surface morphology and cross sections. TEM disclosed that the SCs had a thin shellac sheath layer of approximately 12 nm. XRD and ATR-FTIR results demonstrated that the crystalline DS was converted into amorphous composites with PVP because of favorable secondary interactions. WCA and in vitro dissolution tests demonstrated that the sheath shellac layers in SC could resist acid conditions and provide typical colon-specific pulsatile release, rather than a pulsatile release of HC under acid conditions. Ex vivo permeation results demonstrated that the SCs were able to furnish a tenfold drug permeation rate than the DS particles on the colon membrane.ConclusionA new SC with a shellac coating on hydrophilic amorphous nanocomposites could furnish a colon-specific pulsatile drug release profile. The modified coaxial process can be exploited as a useful tool to create nanocoatings.

Eudragit E100 Nanofibers Fabricated with Varied Solvent Mixtures as the Sheath Working Fluids During Electrospinning

It is still a big concern that how to manipulate the nanofibers’ diameters in an accurate manner. The most recently reported modified coaxial electrospinning, where un-spinnable solvent could be tried as a sheath fluid, is a potential method to achieve this goal. In this study, with Eudragit E100 at a concentration of 15 wt. % in a mixture of ethanol/N, N-dimethylformamide with a volume ratio of 8:2 as the core fluid, a varied of mixed organic solvents were exploited as the sheath fluids to manipulate the sizes of electrospun Eudragit nanofibers. The scanning electron microscopic results demonstrated that the nanofibers’ diameter (D, μm) had a clear exponential relationship with the DMF content (C, %) in the sheath mixtures as D=1.434 - 0.023 C (R=-0.9976) within a rage between 0% to 30%. The microformation mechanism was suggested. The present investigations paved a new way for implementing the modified coaxial processes, which can be utilized to manipulate the diameters of nanofibers robustly and stably.

磁気混合流体を用いたホーニング加工特性と加工中の磁気クラスタの挙動

In this study, we proposed processing the inner surface of cylinder-like parts with a magnetic compound fluid (MCF). We determined the processing characteristics of material removal and the changes in surface roughness and shape accuracy. The processing tool was a round SUS bar with a permanent magnet inserted in it. Processing was performed by coaxial processing and eccentric processing. In the processing experiments, material removal and surface roughness were found to have peak values as the processing surface shear rate increased. An observation experiment was conducted to clarify the behavior of magnetic clusters during MCF processing. We clarified the shape and distribution of the clusters and the processing speeds at various rotation speeds of the processing tool. The magnetic clusters were found to expand with the existence region in material removal peak. Through the processing speed measurement experiment, it was clarified that the MCF exhibits elastic behavior during processing.

Electrospun 4th-Generation Solid Dispersions of Poorly Water-Soluble Drug Utilizing Two Different Processes

Different from traditional solid dispersion (SD) for improving the dissolution rates of poorly water-soluble drugs, the upgraded 4th SD was developed to furnish a drug sustained-release profile. In this work, two different kinds of 4th SDs were fabricated using two electrospinning processes. One is a ternary SD (nanofibers F2) that consisted of ethyl cellulose (EC), polyethylene glycol 1000 (PEG), and tamoxifen citrate (TAM) from a modified coaxial process, and the other is a binary SD (nanofibers F1) which is comprised of EC and TAM from a single-fluid blending process. Scanning electronic microscopic observations demonstrated that F2 (330±50 nm) showed a better quality than F1 (870±230 nm) in terms of size and size distribution although both of them had a smooth surface morphology and a cross section. X-ray diffraction patterns verified that both SDs were amorphous nanocomposites owing to the favorable secondary interactions among these components, as suggested from the results of FTIR. In vitro dissolution experiments indicated that F2 could furnish an improved drug sustained-release characteristics compared to F1, exhausting all the contained TAM and having weaker leveling-off late release. The molecular behaviors of drug sustained-release from the binary 4th SD were suggested. The protocols reported here paved an alternative way for developing novel functional nanomaterials for effective delivery of poorly water-soluble drugs.

Preparing composite nanoparticles for immediate drug release by modifying electrohydrodynamic interfaces during electrospraying

At present, all electrospraying processes are conducted in air environment without considering the importance of electrohydrodynamic interfaces, thereby preventing the development of new possibilities. In this study, a modified coaxial electrospraying process for preparing multicomponent composite nanoparticles was investigated, in which solvents were explored as the shell working fluids to create dynamic air–solvent solution interfaces. The coaxial process was conducted using a blending solution (comprising hydroxypropyl methylcellulose, paracetamol (APAP), and polyvinylpyrrolidone in a mixture of dichloromethane and ethanol) as the core fluid and a solvent mixture as the shell fluid under a series of shell-to-core fluid flow rate ratios. Results demonstrated that the interface modification by the additional shell solvent generated significant influences on the final particulate multicomponent composites. An exponential relationship between the shell-to-core fluid flow rate ratio (F) and the particle diameters (D, μm) could be determined as D=0.54F−0.39 (|R|=0.9890). APAP was amorphously distributed within its solid “cocktails” to form a multicomponent nanocomposite. The resultant particles from the modified coaxial process could provide an immediate drug release, with a best value of four times faster than the counterparts from traditional blending electrospraying. The synergistic actions of particle size, amorphous drug status, and combined usage of hydrophilic polymers could ensure the fast dissolution and immediate release of APAP. The protocols reported in this study paved a new way for developing new types of functional nanomaterials via coaxial electrospraying.

Meletin sustained-release gliadin nanoparticles prepared via solvent surface modification on blending electrospraying

Almost all electrospraying processes are carried out under an air-solution interface, thereby overlooking the potential influence of an additional solvent surface modification between air and the working solution. A pure solvent was explored to temporarily and dynamically surround the solutions utilized for blending electrospraying, which contained a guest drug meletin and a protein drug carrier gliadin. The new modified processes created protein-based medicated nanoparticles (P2) with higher quality than their counterparts (P1) from blending processes, as demonstrated by the SEM and TEM images. Although the particles from the two processes were similar (nanocomposites), and the particles P1 were larger than P2, the later provided a better meletin sustained-release profile than the former. This finding was verified by the smaller initial burst release, longer sustained-release time period, and shorter late leveling-off stage. These unanticipated results were attributed to the rounder surface, the more uniform size distribution, and the smaller total surface area of particles P2 than P1. The microformation mechanism of the modified coaxial process was suggested. The protocols reported here paved a new way for the development of new kinds of functional nanoparticles by modifying the interfaces of working fluids during electrospraying.

Fabrication of sustained-release zein nanoparticles via modified coaxial electrospraying

A modified coaxial electrospraying process, which was characterized by the use of pure solvent as a sheath working fluid, was developed for the continuous and robust generation of medicated nanoparticles. Tamoxifen citrate (TAM) was encapsulated in zein, a plant protein. The influences of the key parameter shell-to-core fluid flow rate on the electrospraying processes and on the resulting protein-based composite particles were investigated in detail. Scanning electron microscopy images revealed that compared with particles prepared via the traditional single-fluid process, TAM-loaded zein particles prepared via the modified coaxial process were rounder with smaller diameters, narrower smaller size distribution, and more compact inner structures. Owing to the reinforced secondary interactions between TAM and zein, all the particles were similarly amorphous composites, as verified by their X-ray patterns and attenuated total reflectance–Fourier transform infrared spectra. The medicated nanoparticles synthesized via the coaxial process exhibited a better drug sustained-release profile than those synthesized via the traditional single-fluid process, with a smaller initial burst release, longer release period, and shorter tailing-off stage. The microformation mechanisms of the electrosprayed particles and their drug sustained-release mechanisms were suggested. By altering the traditional concept of electrospraying, the modified coaxial electrospraying method developed in this study provides a powerful new process for the generation of nanoparticles with novel structures and functions.

Electrosprayed sperical ethylcellulose nanoparticles for an improved sustained-release profile of anticancer drug

A solution treated by electrospraying often has a relatively low polymer concentration, thereby overlooking that pure solvent can be used as an additional working fluid. In this study, a modified coaxial electrospraying, characterized by the usage of pure solvent as a shell fluid, was developed to generate nano drug delivery systems for providing the desired drug sustained-release profiles. Ethylcellulose (EC) and tamoxifen citrate (TC) were exploited as a polymer matrix and a poorly water-soluble anticancer model, respectively. Comparing with those particles prepared using a traditional single-fluid process, the TC-loaded EC particles from the modified coaxial processes have a rounder shape, a smaller diameter, and a highly compact inner structure, as demonstrated by the scanning electron microscopic images. Given the favored secondary interactions between TC and EC, all the particles are similarly amorphous composites, as verified by their X-ray patterns and attenuated total reflectance–Fourier transform infrared spectra. Nevertheless, the rounder nanoparticles from the coaxial processes were able to provide a better drug sustained-release profile than their counterparts in terms of smaller initial burst release, longer release time period, and shorter time tailing-off later stage. Both microformation mechanisms of the medicated particles and drug sustained-release mechanisms are suggested. The protocols developed here facilitate the generation of functional nanomaterials from cellulose and its derivatives owing to breaking the traditional concept of electrospraying.