Advanced Drug Delivery Reviews, Volume 61, Issue 12, 5 October 2009, Pages 1043-1054.

Chakraborty, S., Liao, I.-C., Adler, A., Leong, K.W.

Abstract

Electrospinning and electrospraying are facile electrohydrodynamic fabrication methods that can generate drug delivery systems (DDS) through a one-step process. The nanostructured fiber and particle morphologies produced by these techniques offer tunable release kinetics applicable to diverse biomedical applications. Coaxial electrospinning/electrospraying, a relatively new technique of fabricating core-shell fibers/particles have added to the versatility of these DDS by affording a near zero-order drug release kinetics, dampening of burst release, and applicability to a wider range of bioactive agents. Controllable electrospinning/spraying of fibers and particles and subsequent drug release from these chiefly polymeric vehicles depends on well-defined solution and process parameters. The additional drug delivery capability from electrospun fibers can further enhance the material’s functionality in tissue engineering applications. This review discusses the state-of-the-art of using electrohydrodynamic technique to generate nanofiber/particles as drug delivery devices. © 2009 Elsevier B.V. All rights reserved.

Advanced Materials, Volume 16, Issue 2, 16 January 2004, Pages 166-169

Larsen, G. , Spretz, R., Velarde-Ortiz, R.

Abstract

A novel method to control the stability of Taylor cones during electrospinning/electrospray of solutions with highly volatile solvents is presented. An additional advantage is that fiber-to-particle transitions are also controlled without changing the chemistry or the voltage/current characteristics.

Colloids and Surfaces A, Physicochemical and Engineering Aspects: Volume 382, Issue 1-3, 5 June 2011, Pages 154-164

Enayati, M., Chang, M.-W., Bragman, F., Edirisinghe, M., Stride, E.

Abstract

Electrohydrodynamic (EHD) processing is a method of generating liquid droplets through the application of a large electrical potential difference. It has a wide range of applications in both industrial processes and analytical instrumentation. Research carried out over the last decade has greatly increased the capabilities of EHD processing, providing the capability to coat, print, spin, thread, bubble or encapsulate a wide variety of materials. One of the reasons interest in EHD processing has escalated in recent years is due to its ability to prepare structures at the micro and nano scales. This review paper focuses on the biomedical applications of the various products, especially in drug delivery, and considers the latest achievements in micro- and nano-carrier production. A brief description of the basic physical principles underlying the process is provided and the range of experimental configurations, from single to multi-needle coaxial processing, is examined, together with the resulting structures. Finally the applications of EHD processing and its products are considered, demonstrating its potential, not only for particle and fibre formation, but as a powerful technique for the encapsulation of bioactive materials such as proteins, enzymes, antibiotics and DNA fragments in polymeric particles. © 2010 Elsevier B.V.

Fuhe Cailiao Xuebao/Acta Materiae Compositae Sinica, Volume 22, Issue 6, December 2005, Pages 1-8

He, C., Huang, Z. , Han, X., Liu, L., Hu, Y., Zhang, Y.

Abstract

The fundamental issues and processing principle of electrospinning and electrospray based on electro-hydrodynamics in the fabrication of nanoscale materials are briefly summarized in this article. The special attention is focused on the rapid development in the nanocomposite materials such as nanocapsules, core-shell nanofibers and hollow nanotubes or nanofibers by using coaxial electrospinning and coaxial electrospray in the recent couple of years. Potential applications of these nanocomposites in drug release systems, tissue engineering scaffold, wound dressing and absorbable sutures are discussed. Some future trends are also addressed in the paper.

International Journal of Nanomedicine, Volume 8, 8 August 2013, Pages 2997-3017

Zamani, M., Prabhakaran, M.P. , Ramakrishna, S.

Abstract

Electrohydrodynamic (EHD) techniques refer to procedures that utilize electrostatic forces to fabricate fibers or particles of different shapes with sizes in the nano-range to a few microns through electrically charged fluid jet. Employing different techniques, such as blending, surface modification, and coaxial process, there is a great possibility of incorporating bioactive such molecules as drugs, DNA, and growth factors into the nanostructures fabricated via EHD techniques. By careful selection of materials and processing conditions, desired encapsulation efficiency as well as preserved bioactivity of the therapeutic agents can be achieved. The drug-loaded nanostructures produced can be applied via different routes, such as implantation, injection, and topical or oral administration for a wide range of disease treatment. Taking advantage of the recent developments in EHD techniques like the coaxial process or multilayered structures, individually controlled delivery of multiple drugs is achievable, which is of great demand in cancer therapy and growth-factor delivery. This review summarizes the most recent techniques and postmodification methods to fabricate electrospun nanofibers and electrosprayed particles for drug-delivery applications. © 2013 Zamani et al, publisher and licensee Dove Medical Press Ltd.

Colloids and Surfaces A, Physicochemical and Engineering Aspects, Volume 396, 20 February 2012, Pages 161-1.

Deng-Guang Yu, Gareth R. Williams, Li-Dong Gao, S.W. Annie Bligh, Jun-He Yang, Xia Wang.

Abstract

With sodium dodecylbenzene sulfonate (SDBS) solutions in N,N-Dimethylformamide (DMF) as sheath fluids to surround the core polymer solutions, a series of polyacrylonitrile (PAN) nanofibers with fine diameters, narrow diameter distributions, smooth surfaces and uniform structures have been successfully generated. The fiber diameters (D, nm) could be manipulated through adjusting the SDBS concentration in the sheath fluid (C, mg ml⁻¹) with a scaling law of D = 790 C^−0.41 (R² = 0.9903) within a range of 5–50 mg ml⁻¹. The mechanism of sheath SDBS solutions on the evaporation of DMF and the solidification of core polymer jets is discussed. The replacement of SDBS solutions for traditional atmosphere in single fluid electrospinning can lend itself to smoothen the electrospinning process through adjusting the core solvent evaporation rate. It is concluded that coaxial electrospinning with an ion surfactant solution comprises a facile process for producing high quality polymer nanofibers.

International Journal of Pharmaceutics, Volume 439, Issues 1–2, 15 December 2012, Pages 296-306.

Thuy Thi Thu Nguyen, Chiranjit Ghosh, Seong-Gu Hwang, Noppavan Chanunpanich, Jun Seo Park.

Abstract

This study focused on fabrication and characterization of porous core/sheath structured composite nanofibers with a core of blended salicylic acid (SA) and poly(ethylene glycol) (PEG) and a sheath of poly(lactic acid) (PLA) using a dual-capillary electrospinning system. Results of water contact angle measurements, field-emission scanning electron microscopy, and transmission electron microscopy indicated that feed rates of the core and sheath strongly affect the stability of the core/sheath structure and porous density of the composite nanofibers obtained, significantly influencing their SA release characteristics. At a lower ratio of feed rates of the core and the sheath, better stable core/sheath structures of nanofibers with higher porous density on the surface were formed resulting in a sustained release of SA over 5 days. Non-porous fibers showed a lower amount of drug release because the drug was embedded inside the core layer of the non-porous sheath layer. SA release from porous core/sheath nanofibers was described based on a one-dimensional Fickian diffusion mechanism, indicating that drug diffusion is a predominant factor in drug release. A cytotoxicity test suggested that the porous core/sheath nanofibers are non-toxic and support cell attachment. Therefore, this fiber mat may find application in the design of wound-healing patches with long-term activity.

Journal of Electrostatics, Volume 71, Issue 4, August 2013, Pages 717-727

Soraya Ghayempour, Sayed Majid Mortazavi.

Abstract

This paper considers a new method related to the micro and nanocapsules production by using coaxial jets electrospray. The produced micro–nanocapsules were characterized on their structure, mean particles size and morphology by optical and scanning electron microscope. The effects of different operating parameters on the size of the particles were investigated. The obtained results showed the efficiency of the mentioned method in micro–nanocapsules fabrication. The average diameter of fabricated capsules was variable from 80 nm to 900 μm by adjusting different parameters of process.

Polymer, Volume 53, Issue 24, 9 November 2012, Pages 5523-5539

Gareth M. Bayley, Peter E. Mallon.

Abstract

Graft copolymers of polyacrylonitrile-graft-poly(dimethyl siloxane) (PAN-g-PDMS) were synthesized and the solution electrospinning of these materials from dimethylformamide (DMF) was investigated. The amphiphilic nature of the graft copolymers induced phase segregation and self-assembly of the molecules in the electrospinning solution to form a network-like structure. The self-assembly was shown to have a direct effect on the electrospinning parameters affecting the final fiber morphology. The amphiphilic nature of the molecules led to the formation of porous microfibers. Porous fibers are usually obtained via the selective removal of a polymer component in a co-electrospun solution of polymer blends, however, this works presents a novel and direct route for obtaining highly porous electrospun fibers. Multi-walled carbon nanotubes (MWCNT) were also successfully electrospun in the amphiphilic graft copolymer solutions. The inclusion of MWCNT’s produces fibers with much smaller diameters, but the porous structure of the fibers is maintained. Excellent dispersion and alignment of the nanotubes along the electrospun fiber axis were obtained. It is shown how the porous electrospun fibers can be used as precursor materials for the production of porous carbon fibers.

Journal of Aerosol Science, Volume 42, Issue 4, April 2011, Pages 249-263

Hyun-Ha Kim, Jong-Ho Kim, Atsushi Ogata.

Abstract

A high-speed camera was implemented to visualize the time-resolved fine structure of electrospray of deionized water. This method provided useful visual information on how electrospray initiates, develops and produces water droplets of different sizes. The behavior of different spray mode and its characteristic time-scale were measured. The cone-jet mode subdivided into oscillating cone-jet, rotating cone-jet, stable cone-jet, and unstable cone-jet according to the motion and stability of cone-jet. The size of nozzle also influenced the spray mode. The stable cone-jet mode appeared over a wide range of voltage as the nozzle diameter increased. The hydrodynamic behavior of meniscus or cone-jet played a key role in determining the size of the droplets. Hydrodynamic force induced by vigorous lashing and swirling movement at the jet front was found to play a dominant role in the continuous formation of fine droplets in the cone-jet mode.

Advanced Drug Delivery Reviews, Volume 61, Issue 12, 5 October 2009, Pages 1043-1054

Syandan Chakraborty, I-Chien Liao, Andrew Adler, Kam W. Leong.

Abstract

Electrospinning and electrospraying are facile electrohydrodynamic fabrication methods that can generate drug delivery systems (DDS) through a one-step process. The nanostructured fiber and particle morphologies produced by these techniques offer tunable release kinetics applicable to diverse biomedical applications. Coaxial electrospinning/electrospraying, a relatively new technique of fabricating core–shell fibers/particles have added to the versatility of these DDS by affording a near zero-order drug release kinetics, dampening of burst release, and applicability to a wider range of bioactive agents. Controllable electrospinning/spraying of fibers and particles and subsequent drug release from these chiefly polymeric vehicles depends on well-defined solution and process parameters. The additional drug delivery capability from electrospun fibers can further enhance the material’s functionality in tissue engineering applications. This review discusses the state-of-the-art of using electrohydrodynamic technique to generate nanofiber/particles as drug delivery devices.

Carbon, Volume 53, March 2013, Pages 231-236

Jun-He Yang, Guang-Zhi Yang, Deng-Guang Yu, Xia Wang, Bin Zhao, Lu-Lu Zhang, Peng Du, Xiao-Kang Zhang.

Abstract

A new approach is described for preparing carbon foam (CF) through coaxial electrohydrodynamic atomization (EHDA). Using polyacrylonitrile (PAN) and borneol as a carbonaceous precursor and a blowing agent, respectively, hybrid PAN-borneol films were prepared and transferred to a honeycomb PAN membrane through blowing, drying, and pre-oxidation with the CF prepared by carbonization of the PAN film. Scanning electron microscopy observations showed that the CF has a homogeneous structure, having pores with an average diameter of 2.34 ± 0.73 μm. The surface of the CF, which had a thickness of 10 μm, was smooth and compact. The coaxial EHDA process can be exploited for preparing CF with tailored structures.

Comprehensive Biomaterials, Volume 1, 2011, Pages 497-512

P.K. Bhattacharjee, G.C. Rutledge

Abstract

Electrospinning is a popular technique for manufacturing nanofibers using an electrified jet of a polymeric fluid. The fibrous, nonwoven mat that typically results from electrospinning finds applications in a wide range of industries. While setting up an electrospinning experiment is relatively simple, controlling the attributes of the end-products, such as the diameter and morphology of the fiber formed, the orientation of the deposited fiber, the porosity, and the surface properties of the resultant mat, etc., is considerably more challenging. Significant progress has been made in recent years in understanding the physical mechanisms that govern the process of fiber formation through electrospinning. This chapter reviews these advances and provides an overview of the present status of the technology. The process of electrospinning is outlined and the mathematical framework for studying the mechanics involved is discussed. The relevant electrical and the rheological aspects of polymeric fluids are also reviewed. An account of the advances in controlling the fiber diameter, morphology, and surface properties, as well as in controlling the properties of the mat, is provided. This chapter also discusses the limitations of the current technology and provides a perspective for future developments.

Journal of Food Engineering, Volume 98, Issue 3, June 2010, Pages 370-376

Saowakon Wongsasulak, Manashuen Patapeejumruswong, Jochen Weiss, Pitt Supaphol, Tipaporn Yoovidhya.

Abstract

Edible nanofibrous thin films were fabricated for the first time from blend solutions of cellulose acetate (CA) in 85% acetic acid and egg albumen (EA) in 50% formic acid by electrospinning. The mass percentage ratios of CA–EA in the mixed solvents varied from 100:0 to 91:9, 77:23, 66:34 and 0:100. Effects of the blend ratios on the solution properties and morphology of the resulting electrospun products were studied. The results showed that EA lacked sufficient entanglement and also possessed very high surface tension, thereby being unable to form nanofibers. The addition of CA and surfactant (Tween40®) decreased both the electrical conductivity and the surface tension of the blends (p < 0.05), which facilitated the formation of CA–EA blend nanofibers. Scanning electron microscopic images showed that the continuity of the blend fibers was improved with an increase in the EA ratio. Fourier-transformed infrared spectroscopy and thermo-gravimetric analysis results indicated that the obtained fibers were composed of both CA and EA constituents. This study demonstrated a potential to fabricate edible nanofibers from natural food biopolymers using the electrospinning technique. Due to the properties of EA, these nanofibers could provide new functionalities with respect to in vivo-controlled release of nutraceuticals and drugs

Chemical Engineering Journal, Volume 169, Issues 1–3, 1 May 2011, Pages 348-357

Sehyun Park, Sunae Hwang, Jonghwi Lee.

Abstract

Physical gelation between two polymers of opposite charges has potential applications in hydrogel delivery systems. However, issues associated with physical gelation, such as gelation control, effective drug loading, and stability before delivery, have limited the application of this technique. We, therefore, investigated gelable composite particles, because drugs can be effectively loaded inside a core with a less hydrophilic protective shell, and, later, the composite particles can be gelled into any shape in water. A modified spray drying apparatus was built by introducing a customized coaxial nozzle and applying a high electric potential between the nozzle and a ground in the air flow channel for convenient preparation of gelable composite particles. The resulting particles were molded into more elastic hydrogels by the addition of water than those prepared by the gelation of powder physical mixtures, and their pH-dependent equilibrium swelling could be tailored to a wide range. The release rate of a model drug (lipoic acid) appears to reflect the composite structures. As the applied voltage was increased, more sustained release and lower equilibrium swelling resulted. This novel preparation technique and the resulting gelable structured particles have potential applications in drug (proteins) delivery systems, wound healing hydrogels, protein-releasing scaffolds, etc.

Acta Biomaterialia, Volume 8, Issue 2, February 2012, Pages 811-819

Jingwei Xie, Eric R. Blough, Chi-Hwa Wang

Abstract

Herein we describe a method to fabricate submicron bioactive glass tubes using sol–gel and coaxial electrospinning techniques for applications in bone tissue engineering. Heavy mineral oil and gel solution were delivered by two independent syringe pumps during the coaxial electrospinning process. Subsequently, submicron bioactive glass tubes were obtained by removal of poly(vinyl pyrrolidone) and heavy mineral oil via calcination at 600 °C for 5 h. Tubular structure was confirmed by scanning electron microscopy and transmission electron microscopy imaging. We examined the bioactivity of submicron bioactive glass tubes and fibers and evaluated their biocompatibility, using electrospun poly(ε-caprolactone) fibers – a bioinactive material – for comparison. The bioactivity of the glass tubes was examined in a simulated body fluid and they demonstrated the formation of hydroxyapatite-like minerals on both the outer and inner surfaces. In contrast, mineralization only occurred on their surface for bioactive glass solid fibers. Energy-dispersive X-ray data suggested that the bioactive glass tubes had a faster induction of mineral formation than the solid fibers. We demonstrate that the proliferation rate of mouse preosteoblastic MC3T3-E1 cells on bioactive glass tubes was comparable to that on solid fibers. We also show that bioactive glass tubes can be loaded with a model protein drug, bovine serum albumin, and that these structures exhibit delayed release properties. The bioactivity of released lysozyme can be as high as 90.9%. Taken together, these data suggest that submicron bioactive glass tubes could hold great potential for use in bone tissue engineering as well as topical drug or gene delivery.

Polymer, Volume 49, Issue 26, 8 December 2008, Pages 5603-5621

Seema Agarwal, Joachim H. Wendorff, Andreas Greiner

Abstract

The electrospinning technique provides non-wovens to the order of few nanometers with large surface areas, ease of functionalisation for various purposes and superior mechanical properties. Also, the possibility of large scale productions combined with the simplicity of the process makes this technique very attractive for many different applications. Biomedical field is one of the important application areas among others utilising the technique of electrospinning like filtration and protective material, electrical and optical applications, sensors, nanofiber reinforced composites etc. Electrospinning assembly can be modified in different ways for combining materials properties with different morphological structures for these applications. The importance of electrospinning, in general, for biomedical applications like tissue engineering drug release, wound dressing, enzyme immobilization etc. is highlighted in this feature article. The focus is also on the types of materials that have been electrospun and the modifications that have been carried out in conventional electrospinning apparatus keeping in view the specific needs for various biomedical applications.

Comprehensive Biomaterials, Volume 4, 2011, Pages 445-462

W. Cui, J. Chang, P.D. Dalton

Abstract

The past decade has seen a remarkable surge of interest in the electrostatic drawing of fibers (electrospinning), particularly for biomedical applications in regenerative medicine. The inexpensive nature of electrospinning has enabled biomedical researchers to use ultrafine diameter fibers for tissue engineering and drug delivery purposes. Research in electrospun fibers for drug delivery is exponentially increasing, and often accompanied by the need to make these fibrous materials cell invasive for tissue engineering. This and other challenges for biomedical electrospinning are being identified and tackled within the research community. The result is an increasingly diverse approach to electrospinning, with numerous options for both scaffold manufacture and drug release. For example, coaxial electrospinning is altering the release profiles of drugs, while improvements in surface modification incorporated specific bioactive compounds with reduced fouling by nonspecific protein adsorption. While challenges remain, approaches for cell-invasive electrospun materials are maturing so that this technique can become a powerful new tool in regenerative medicine. The potential and huge interest generated after less than 10 years of electrospinning research indicates that the next decade will also be dynamic for this technique.

Progress in Polymer Science Volume 37, Issue 11, November 2012, Pages 1510–1551

N. Bock, T.R. Dargaville, M.A. Woodruff.

Abstract

The encapsulation and release of bioactive molecules from polymeric vehicles represents the holy grail of drug and growth factor delivery therapies, whereby sustained and controlled release is crucial in eliciting a positive therapeutic effect. To this end, electrospraying is rapidly emerging as a popular technology for the production of polymeric particles containing bioactive molecules. Compared with traditional emulsion fabrication techniques, electrospraying has the potential to reduce denaturation of protein drugs and affords tighter regulation over particle size distribution and morphology. In this article, we review the importance of the electrospraying parameters that enable reproducible tailoring of the particles’ physical and in vitro drug release characteristics, along with discussion of existing in vivo data. Controlled morphology and monodispersity of particles can be achieved with electrospraying, with high encapsulation efficiencies and without unfavorable denaturation of bioactive molecules throughout the process. Finally, the combination of electrospraying with electrospun scaffolds, with an emphasis on tissue regeneration is reviewed, depicting a technique in its relative infancy but holding great promise for the future of regenerative medicine.

Polymer Volume 52, Issue 15, 7 July 2011, Pages 3325–3336

Woojin Kim, Sang Soo Kim

Abstract

An electrospray system incorporating a triaxial capillary device was used to fabricate biodegradable, multi-shell capsules for use as a drug delivery system. Triple-layered capsules composed of poly(lactic-co-glycolic acid) (PLGA) and poly(DL-lactic acid) (PDLLA) were synthesized by electrospray drying and the formation and characteristics of the capsules were studied under a variety of experimental conditions. The size distribution and morphology of the capsules were determined using phase-Doppler particle analysis (PDPA), field emission scanning electron microscope (FE-SEM), and laser scan.