Electrospray Method Research Articles

Flame Retardation of Polyamide 6 by Electro-Sprayed Phosphorus–Copper Complex Supported by Layered Silicate

The primary objective of this study was to demonstrate the effect of a phosphorus–copper complex on the flammability of polyamide 6 (PA6) materials, including organoclay-reinforced nanocomposites. The secondary objective was to compare the effectiveness of the deposition methods of the three-layer copper complex. Our previous work successfully revealed the effectiveness of reducing the flammability of polyamide composites by depositing phosphorus and copper compounds using a Layer-by-Layer technique. In the current work, we turned our attention to modifying the PA6 surface by electro-spray (ES) using the same flame retardants as before, and we investigated the effectiveness of the resulting surface protection against high temperatures during combustion. Surface roughness analysis revealed that the use of the ES method favors the formation of surface unevenness. The UL-94 test results showed that composite materials having 5-15 triple layers were among the best flammability classes compared to the others. Both types of materials tested also showed a tendency to reduce the heat release rate (HRR) by increasing the degree of surface coverage when using the electro-spray technique. Remarkably, deposition of 15 triple layers on the surface of the nanocomposite reduced the maximum HRR point by 20%.Graphical abstract

Synthesis and characterization of submicron spherical core-shell high-energy composites via electrospray method

In this study, submicron spherical core-shell high-energy composites of RDX/F2311@CuO/Al were synthesized using the electrospray method. The results demonstrate that the combustion time of composite high-energy microspheres, prepared via electrospraying, was significantly reduced to 460.0 ms from an original 2296.0 ms observed in samples prepared by physical mixing. Additionally, the flame burning was more concentrated, and the combustion process exhibited greater stability. Additionally, the flame combustion exhibited greater concentration and the overall combustion process was more stable. Furthermore, by manipulating the proportion of non-energy-containing components, it is possible to obtain composites with adjustable combustion rates. By manipulating the ratio of aluminium thermal agent, it is possible to procure a composite material with a more vigorous combustion process, thereby enabling the functional modulation of said composite material. Compared to the raw material RDX, the H50 value of the composite microspheres has increased from 14.49 cm to 25.16 cm, indicating a significant enhancement in impact resistance along with a remarkable desensitization effect. Additionally, the explosion percentage of the composite microspheres has been reduced from 84 % to 68 %. These significant desensitization effects highlight the morphological advantages of the core-shell structure and the synergistic reaction energy benefits of the components involved.

Development of Multiple Electrospray Nozzles for Fabricating Catalyst Layers of Polymer Electrolyte Fuel Cells

The electrospray (ES) method can be used to make porous, high-performance and low-Pt-loading catalyst layers (CLs). In our group’s previous work, we succeeded in improving the cell performance in low-Pt-loading polymer electrolyte fuel cell cathode CLs by the use of a single-pin-nozzle ES method. However, the coating amount of the ES method is too low to be applied in mass production. In the present work, we have developed multi-pin nozzles. We started with the examination of two single-pin nozzles and confirmed that the ES method with plural nozzle pins was possible. We created a seven-pin nozzle as the first multi-pin nozzle. The uniformity of both the amount and scattering direction of the ink emission from that nozzle was deficient. We found that electrostatic-field control pins and plate were effective in correcting the behavior. Next, we created a 12-pin nozzle that was also equipped with electrostatic-field control pins and plate. We examined the length of the electrostatic-field control pins and the pin pitch with that nozzle. Finally, we increased the number of the nozzle pins to 72. The cathode CLs coated with that nozzle exhibited higher uniformity and cell performance in comparison with CLs coated by use of the pulse-swirl-spray method.

Enhancing power conversion efficiency of polycrystalline silicon photovoltaic cells using yttrium oxide anti-reflective coating via electro-spraying method

The achievement of optimal performance is a crucial aspect of renewable energy resources. The study attempts to boost the power conversion efficiency of polycrystalline silicon (Si) photovoltaic cells by the application of anti-reflective coating (ARC). The solgel method is employed to synthesize yttrium oxide (Y2O3). The electro spraying method was utilized to apply the ARC on photovoltaic cells. The effect of coating on PV cells were determined through the structural, electrical, optical and thermal analysis. The antireflective material was uniformly applied over the coated substrate for 45 min (Y-I), 90 min (Y-II), 135 min (Y-III), and 180 min (Y-IV). The sample coated for 135 min showed an optimal power conversion efficiency (PCE) of 21.65 % and 20.09 % in the presence of neodymium light and direct sunlight, respectively, and a minimum electrical resistivity of 3.96 × 10−3 Ω-cm. In addition, Y-III coated cells exhibit a maximum absorbance of 94 %. The Y-III coated photovoltaic cells demonstrated the lowest temperature of 34.6 °C when exposed to an open environment and 40.6 °C when exposed to a controlled environment. The results from numerous studies demonstrated that Y2O3 can be a suitable ARC, which effectively improved the efficiency of photovoltaic cells.

Superimposed Electric Field Enhanced Electrospray for High-Throughput and Consistent Cell Encapsulation.

Cell encapsulation technology, crucial for advanced biomedical applications, faces challenges in existing microfluidic and electrospray methods. Microfluidic techniques, while precise, can damage vulnerable cells, and conventional electrospray methods often encounter instability and capsule breakage during high-throughput encapsulation. Inspired by the transformation of the working state from unstable dripping to stable jetting triggered by local electric potential, this study introduces a superimposed electric field (SEF)-enhanced electrospray method for cell encapsulation, with improved stability and biocompatibility. Utilizing stiffness theory, the stability of the electrospray, whose stiffness is five times stronger under conical confinement, is quantitatively analyzed. The SEF technique enables rapid, continuous production of ≈300 core-shell capsules per second in an aqueous environment, significantly improving cell encapsulation efficiency. This method demonstrates remarkable potential as exemplified in two key applications: (1) a 92-fold increase in human-derived induced pluripotent stem cells (iPSCs) expansion over 10 d, outperforming traditional 2D cultures in both growth rate and pluripotency maintenance, and (2) the development of liver capsules for steatosis modeling, exhibiting normal function and biomimetic lipid accumulation. The SEF-enhanced electrospray method presents a significant advancement in cell encapsulation technology. It offers a more efficient, stable, and biocompatible approach for clinical transplantation, drug screening, and cell therapy.

Low-frequency and broadband electromagnetic wave absorption mechanism of (Hf0.2Zr0.2Ti0.2Ce0.2La0.2)C1-δ/PyC microspheres with hierarchy pores from 4 GHz to 17 GHz

Achieving low-frequency broadband electromagnetic wave absorption in extreme environments over 2000 °C is challenging. Biomimetic hierarchy materials of high entropy lanthanide carbides were designed to optimize electromagnetic wave absorption. Composite microspheres of (Hf0.2Zr0.2Ti0.2Ce0.2La0.2)C1-δ and SiC embedded in pyrolytic carbon (MC/PyC) were prepared by using the electro-spray method followed by heat treatment. The specimens of MC/PyC microspheres with a thickness of 2.5 mm exhibited a minimum reflection loss value of − 48.9 dB, and electromagnetic wave absorption from 4.0 GHz to 17 GHz. The enhanced absorption capability is attributed to the synergistic effect of dielectric losses from conduction and polarization, along with magnetic losses due to eddy currents and natural resonance of the high-entropy carbides within the multiscale pores. The composition and featured microstructure MC/PyC microspheres were noteworthily stable under the 2200 °C oxyacetylene ablation, ensuring consistent high-performance electromagnetic wave absorption even in harsh conditions.

Comparative Study of Electrochromic Supercapacitor Electrodes Based on PEDOT:PSS/ITO Fabricated via Spray and Electrospray Methods.

PSS stands out as a leading commercial conducting polymer due to its excellent water dispersibility, controllable miscibility, adjustable conductivity, and ability to form films through various techniques. This study investigates the electrochemical and electrochromic performance of electrodes prepared by depositing PEDOT:PSS onto ITO surfaces by using two distinct methods: conventional spray coating and electrospray deposition. Detailed characterization of the prepared electrodes was performed by using atomic force microscopy, scanning electron microscopy, Fourier-transform infrared, and Raman spectroscopy techniques. Our findings reveal that electrodes fabricated via electrospray deposition (PEDOT:PSS/ITO electrode_2) significantly outperform those made by spray coating (PEDOT:PSS/ITO electrode_1). Specifically, electrode_2 exhibits a capacitance of 1678.60 μF cm-2, compared to 826.14 μF cm-2 for electrode_1, at a current density of 10 μA cm-2. PSS electrodes exhibit areal energy densities of 0.41 and 0.84 mW h cm-2, along with power densities of 4.96 and 4.97 μW cm-2, respectively. Moreover, electrode_2 demonstrates a high coloration efficiency of 84.32 cm2 C-1 and fast response times of 1.36 s for coloration and 0.98 s for bleaching. This study highlights the advantages of electrospray deposition over traditional methods, showcasing the potential of electrospray-prepared PEDOT:PSS electrodes for use in multifunctional energy storage devices.

Double protection of probiotics in alginate hydrogel through emulsification incorporated with freeze drying and coaxial wet-electrospraying: Survivability and targeted delivery

Two probiotic strains were co-encapsulated in water in oil emulsion by two methods: (1) coaxial wet electrospraying and (2) freeze-drying methods. Optimization of the wet electrospray technique for maximum yield, minimum sphericity factor, and size resulted in an alginate concentration of 2.99% w/v, flow rates ratio of alginate to the emulsion of 4.81, and applied voltage of 10 kV. The cell viability of Lactobacillus plantarum PTCC 1896 was the same after both encapsulation techniques, while the freeze-drying method was more impressive (97.25%) than the coaxial electrospraying (86.46%) in maintaining the viability of Bifidobacterium animalis subsp. Lactis. Exposing electrospray-encapsulated probiotics to simulated gastrointestinal conditions for 4 h resulted in only a one logarithmic cycle decrease in the viability of both bacteria. The number of live cells remained at more than 108 CFU g−1. In contrast, the viability of freeze-dried probiotics was reduced to about 107 CFU g−1. The freeze-dried B. lactis was the most sensitive probiotic to simulated gastric conditions. Monitoring the viability of bacteria during storage at −18 °C for both wet electrospraying and freeze-drying methods showed that the number of living microorganisms was more than 6 Log CFU g−1 after 5 and 4 months, respectively.

Comparative studies of GelMA hydrogels: investigating the effect of different source on mechanical, physical and biological properties

GelMA hydrogels are prominent in biomedical applications due to their innate extracellular matrix mimicking properties. They exhibit favorable properties for cell proliferation and formation of light-induced hydrophilic cross-linked structures. However, there is limited research on the effect of variations in the starting material (gelatin) on the physical, mechanical and biological properties. In this study, Gelatin Methacrylic Anhydride (GelMA) hydrogels were synthesized from two different products of type B gelatin and loaded with polyvinylpyrrolidone (PVP) nanoparticles by electrospray method. Chemical and structural analyses were performed by FTIR, 1HNMR, TNBS and SEM, respectively. Mechanical properties were evaluated by compression tests. Cytocompatibility was evaluated by XTT analysis. GelMA hydrogels obtained from two brands have suitable pore size, mechanical strength, swelling properties and cytocompatibility, making them suitable for various biomedical applications. In addition, the addition of PVP nanoparticles can make them useful for drug delivery applications.

Optimization of Electrospray Deposition Conditions of ZnO Thin Films for Ammonia Sensing.

This study focuses on the influence of electrospray deposition parameters on the morphology, topography, optical and sensing properties of ZnO films deposited on gold electrodes of quartz crystal resonators. The substrate temperature, precursor feed rate and emitter's voltage were varied. Zinc acetate dehydrate dissolved in a mixture of deionized water, ethanol and acetic acid was used as a precursor. The surface morphology and average roughness of the films were studied by scanning electron microscopy (SEM) and 3D optical profilometry, respectively, while the optical properties were investigated by diffuse reflectance and photoluminescence measurements. The sensing response toward ammonia was tested and verified by the quartz crystal microbalance (QCM) method. The studies demonstrated that electrospray deposition parameters strongly influence the surface morphology, roughness and gas sensing properties of the films. The deposition parameters were optimized in order for the highest sensitivity toward ammonia to be achieved. The successful implementation of the electrospray method as a simple, versatile and low-cost method for deposition of ammonia-sensitive and selective ZnO films used as a sensing medium in QCM sensors was demonstrated and discussed.

Preparation and Properties of Dye-Sensitizing Graphene/TiO2 based Photocatalytic Composite Film by Electrospray Method

Preparation and Properties of Dye-Sensitizing Graphene/TiO2 based Photocatalytic Composite Film by Electrospray Method

Alginate functionalized chitosan nanoparticles using multilayer co-axial electro-spraying for ovalbumin controlled release via oral delivery

The current oral vaccine delivery presents numerous challenges due to physiological barriers in the gastrointestinal tract including antigen degradation by enzymes and gastric pH conditions. Contributing to overcome these problems, this work developed non-cross-linked chitosan (CHI) nanoparticles, with/without functionalization with alginate (ALG), using multilayer co-axial electro-spraying method, to orally deliver ovalbumin (OVA), a model antigen. The prepared OVA@CHI and OVA@CHI@ALG nanoparticles possessed spherical shape, uniform size and non-agglomeration, high OVA encapsulation efficiency of above 90 %, and core-shell structure with mean diameters of 276.9 ± 70.7 nm (for OVA@CHI) and 304.3 ± 63.9 nm (for OVA@CHI@ALG), determined via SEM images. The particle hydrodynamic diameters, analyzed by the DLS method, were 313.0 ± 72.4 nm for OVA@CHI and 367.6 ± 83.2 nm for OVA@CHI@ALG, in agreement with the SEM results. Additionally, the material functional group interactions and the polyelectrolyte complex formations were confirmed by FTIR spectra and TGA/DSC thermo-grams, indicating the successful formulation. Subsequently, the OVA@CHI@ALG nanoparticles revealed good stability in acidic environment under the presence of digestive enzymes. The OVA release profiles of OVA@CHI@ALG nanoparticles exhibited limited release in simulated gastric fluid (pH 1.2), followed by sustained release in simulated intestinal fluid (pH 6.8) and simulated colonic fluid (pH 7.4) over a 48-h test period. Interestingly, the primary structure of OVA, analyzed by SDS-PAGE analysis, was maintained during the preparation process and after the release test, while the OVA secondary structure, examined by circular dichroism measurement, demonstrated a decrease of α-helix and an increase of β-sheet contents. Finally, the in vitro mucin-binding study indicated a significant adhesive efficiency of 69.21 ± 4.24 % for OVA@CHI and 75.07 ± 2.58 % for OVA@CHI@ALG at pH 7.4. Conclusively, the OVA@CHI@ALG nanoparticles fabricated by tri-axial electro-spraying method could be a promising oral vaccine delivery system for sustained release of OVA.

Green Electrospun Poly(vinyl alcohol)/Gelatin-Based Nanofibrous Membrane by Incorporating 45S5 Bioglass Nanoparticles and Urea for Wound Dressing Applications: Characterization and In Vitro and In Vivo Evaluations.

This study reports the fabrication and characterization of poly(vinyl alcohol) (PVA) and gelatin (Gel)-based nanofiber membranes cross-linked with citric acid (CA) by a green electrospinning method in which nano 45S5 bioglass (BG) and urea were incorporated. Various combinations of PVA, gelatin, and BG were prepared, and nanofiber membranes with average fiber diameters between 238 and 595 nm were fabricated. Morphological, chemical, and mechanical properties, porosity, swelling, water retention, and water vapor transmission rate of the fabricated membranes were evaluated. PVA:Gel (90:10), 15% CA, and 3% BG were determined as the optimum blend for nanofiber membrane fabrication via electrospinning. The membrane obtained using this blend was further functionalized with 10% w/w polymer urea coating by the electrospray method following the cross-linking. In vitro biocompatibility tests revealed that the fabricated membranes were all biocompatible except for the one that functionalized with urea. In vivo macroscopic and histopathological analysis results of PVA/Gel/BG and PVA/Gel/BG/Urea treated wounds indicated increased collagenization and vascularization and had an anti-inflammatory effect. Furthermore, careful examination of the in vivo macroscopic results of the PVA/Gel/BG/Urea membrane indicated its potential to decrease uneven scar formation. In conclusion, developed PVA/Gel/BG and PVA/Gel/BG/Urea electrospun membranes with multifunctional and biomimetic features may have the potential to be used as beneficial wound dressings.

Porous Microspheres as Pathogen Traps for Sepsis Therapy: Capturing Active Pathogens and Alleviating Inflammatory Reactions.

Sepsis is a systemic inflammatory response syndrome caused by pathogen infection, while the current antibiotics mainly utilized in clinical practice to combat infection result in the release of pathogen-associated molecular patterns (PAMPs) in the body. Herein, we provide an innovative strategy for controlling sepsis, namely, capturing active pathogens by means of extracorporeal blood purification. Carbon nanotubes (CNTs) were modified with dimethyldiallylammonium chloride (DDA) through γ-ray irradiation-induced graft polymerization to confer a positive charge. Then, CNT-DDAs are blended with polyurethane (PU) to prepare porous microspheres using the electro-spraying method. The obtained microspheres with a pore diameter of 2 μm served as pathogen traps and are termed as PU-CNT-DDA microspheres. Even at a high flow rate of 50 mL·min-1, the capture efficiencies of the PU-CNT-DDAs for Escherichia coli and Staphylococcus aureus remained 94.7% and 98.8%, respectively. This approach circumvents pathogen lysis and mortality, significantly curtails the release of PAMPs, and hampers the production of pro-inflammatory cytokines. Therefore, hemoperfusion using porous PU-CNT-DDAs as pathogen traps to capture active pathogens and alleviate inflammation opens a new route for sepsis therapy.

Curcumin‐Encapsulated Poly(lactic‐co‐glycolic acid) Nanoparticles: A Comparison of Drug Release Kinetics from Particles Prepared via Electrospray and Nanoprecipitation

AbstractControlled drug release (CDR) is a significant field of research in medical sciences due to its numerous clinical advantages over traditional methods. Encapsulation of a drug in a polymeric matrix is common technique to achieve CDR. In this study, drug‐polymer particles are prepared using poly(lactic‐co‐glycolic acid) (PLGA) as the polymer and curcumin (CUR) as model drug. Two different methods, electrospray and nanoprecipitation, are used to prepare the particles, and optimal samples in each process are selected based on size and polydispersity index (PDI). Samples are characterized using various tests, and entrapment efficiency (EE%) and drug loading (DL%) are calculated using UV spectroscopy. The results showed that nanoprecipitated and electrosprayed PLGA particles successfully encapsulated CUR, with higher encapsulation efficiency (93.2%) and loading capacity (7.2%) for electrosprayed particles. The in vitro drug release showed that electrospray particles have a slower release rate due to higher encapsulation efficiency. The electrospray method turned out to be more viable for synthesizing these polymer‐drug particles due to smaller particle size, lower PDI, higher entrapment efficiency, and drug loading percentage. Finally, the antibacterial behavior of the particles proved that prepared particles provide excellent antibacterial efficacy (99.9%) and can be used as drug delivery systems.

Preparation of RDX/F2311/Fe2O3/Al Composite Hollow Microspheres by Electrospray and Synergistic Energy Release during Combustion between Components.

Nanothermites and high-energy explosives have significantly improved the performance of high-energy composites and have broad application prospects. Therefore, in this study, RDX/F2311/Fe2O3/Al composite hollow microspheres were successfully prepared utilizing the electrospray method using F2311 as a binder between components. The results show that the combustion time of the composite hollow microspheres is shortened from 2400 ms to 950 ms, the combustion process is more stable, and the energy release is more concentrated. The H50 of the composite hollow microspheres increased from 14.49 cm to 24.57 cm, the explosion percentage decreased from 84% to 72%, and the sensitivity of the composite samples decreased significantly. This is mainly the result of the combination of homogeneous composition and synergistic reactions. The combustion results show that F2311 as a binder affects the tightness of the contact between the components. By adjusting its content, the combustion time and the intensity of the combustion of the composite microspheres can be adjusted, which provides a feasible direction for its practical application.

Studying and Characterization of Coating of Zein-CaSiO3 Composite on Polyetheretherketone Implant Material.

Material-coated implants are placed in the bone and play an essential role in bone regeneration and rapid healing around implants. Polymeric matrix reinforced with ceramic materials is a promising composite material for coating implants. This study aims to determine the effect of mixing various concentrations of zein with CaSiO3 on polyetheretherketone (PEEK) as implant material. The coating was performed using the electrospray method. PEEK disks were used as a control group. The coated disks with different concentrations of zein-CaSiO3 (Group 1: 10% wt, 90% wt), (Group 2: 20% wt, 80% wt), and (Group 3%: 30% wt, 70% wt) were the experimental group. Each group was characterized by atomic force microscopy, field emission scanning electron microscope, Fourier-transform infrared spectroscopy, water contact angle, and adhesion strength. The lowest water contact angle was obtained for Group 1: 10% wt and 90% wt were (26.64° and 27.13°, respectively), and increasing amounts of zein in comparison to quantities of CaSiO3 resulted in increased adhesion strength of the composite material to the substrate. The current study suggested that the higher amount of zein compared to the amount of CaSiO3 mixture coating is achieved by electrospraying, a favorable candidate for coating implants compared to uncoated and coated disks with low concentrations of zein compared to concentrations of CaSiO3.

Facile encapsulation of cyanoacrylate-based bioadhesive by electrospray method and investigation of the process parameters

Polymer microcapsules containing cyanoacrylates have represented a promising option to develop self-healing biomaterials. This study aims to develop an electrospray method for the preparation of capsules using poly(methyl methacrylate) (PMMA) as the encapsulant and ethyl 2-cyanoacrylate (EC) as the encapsulate. It also aims to study the effect of the electrospray process parameters on the size and morphology of the capsules. The capsules were characterized using Fourier-transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), and field-emission scanning electron microscopy (FE-SEM). Moreover, the effects of electrospray process parameters on the size were investigated by Taguchi experimental design. FTIR and TGA approved the presence of both PMMA and EC without further reaction. FE-SEM micrograph demonstrated that an appropriate choice of solvents, utilizing an appropriate PMMA:EC ratio and sufficient PMMA concentration are critical factors to produce capsules dominantly with an intact and spherical morphology. Utilizing various flow rates (0.3–0.5 ml/h) and applied voltage (18–26 kV), capsules were obtained with a 600–1000 nm size range. At constantly applied voltages, the increase in flow rate increased the capsule size up to 40% (ANOVA, p ≤ 0.05), while at constant flow rates, the increase in applied voltage reduced the average capsule size by 3.4–26% (ANOVA, p ≤ 0.05). The results from the Taguchi design represented the significance of solution flow rate, applied voltage, and solution concentration. It was shown that the most effective parameter on the size of capsules is flow rate. This research demonstrated that electrospray can be utilized as a convenient method for the preparation of sub-micron PMMA capsules containing EC. Furthermore, the morphology of the capsules is dominated by solvents, PMMA concentration, and PMMA:EC ratio, while the average size of the capsules can be altered by adjusting the flow rate and applied voltage of the electrospray process.

Electrospray doxorubicin‐loaded polycaprolactone‐polyethylene glycol nanospheres/poloxamer‐chitosan thermogel: A promising candidate for clinical applications

AbstractIn recent years, polymer nanospheres have been considered as one of the most common materials in the drug delivery domain. In this research, polycaprolactone‐polyethylene glycol (PCL‐PEG) blend nanospheres were produced using the electrospray method to load doxorubicin. Also, these nanospheres can be used for injection in the treatment site by poloxamer‐chitosan thermogel. In this research, PCL and PEG were used as raw materials to produce nanospheres. Then, doxorubicin was used for loading in nanospheres. The electrospray method was chosen as the method of nanosphere production. In the next step, poloxamer‐chitosan thermogel was used for injection at the treatment site. In this method, Fourier transform infrared spectroscopy, scanning electron microscopy, and rheometer techniques were used to identify the compounds and properties of the obtained specimens. Also, the MTT test was used to investigate toxicity. The results showed that PCL‐PEG polymer nanospheres were produced by loading doxorubicin using the electrospraying method with a diameter of 185 ± 23 nm. Also, these nanospheres were used for injection in the treatment site using poloxamer‐chitosan thermogel. The amount of drug release in the PLX‐CS (DOX‐PCL‐PEG)NSs was 63% in 144 h at medium pH 5.5. In the drug release system, the in‐vitro method was utilized to study the release of PLX‐CS (DOX‐PCL‐PEG) NSs. PCL‐PEG nanospheres combined in poloxamer‐chitosan thermogel polymer showed the controlled release of doxorubicin, therefore, the evaluated drug release system is considered a valuable perspective as an efficient and safe route for drug delivery in the target tissue and treating various types of cancer. This research can be used as a new method in drug delivery systems.

In-flight electro-neutralisation electrospray for pulmonary drug delivery

Pulmonary drug delivery does not only provide non-invasive therapy for local lung diseases but also remarkably enhances systemic absorption of therapeutics owing to the tremendous surface area of the lung and fast transport of active molecules across the respiratory epithelia. In comparison to traditional delivery systems, electrohydrodynamic atomisation (EHDA) is superior in terms of size and production rate control but the high surface charges of resulting particles prohibit its use in drug delivery. To overcome this challenge, we developed an in-flight electro-neutralisation electrospray (IFENE) method which enables the generation of mists of particles in respirable size range with little to no charge. Our approach uses low-frequency alternating current (AC) to produce charge-neutralised sprays with initial velocity due to oppositely charged droplets combination. Experiments and simulations with pure liquid as the working solution were conducted to reveal the underlying mechanism. The applied frequency is found to be the main factor that influences spray stability and formation. Poly (vinylidene fluoride) (PVDF) and PVDF with curcumin solution were electrosprayed via IFENE, producing sprays of organic particles with controlled sizes and neutralised charges. The capability of coupling particle generation in the respirable size range (below 5 μm) and charge reduction (under 400 femtoamperes), along with its simple setup makes IFENE a promising platform technology in inhalation drug delivery.