Electrospray Method Research Articles

Micro/nanoscale surface engineering to enhance hemocompatibility and reduce bacterial adhesion for cardiovascular implants

Precise engineering of surface properties is essential for improving bio/hemocompatibility of medical implants. In this study, potential of electrospraying (ES) as a coating method to control surface properties was evaluated in vitro. Poly (lactic acid) was coated on 316 L stainless steel plates by ES and spin-coating methods. Surface topography and morphology were studied using confocal and scanning electron microscope (SEM), respectively. Surface hydrophobicity and mechanical properties were investigated by contact angle and nanoindentation tests. Hemocompatibility of samples evaluated using protein adsorption, hemolysis, blood coagulation, complement system and leukocyte activation experiments. Platelet response to the coatings was examined using LDH assay, SEM and ELISA tests. Cell viability studies performed on human endothelial cells using MTT assay and SEM after 1, 4 and 7 days. SEM was used to consider formation of pseudomonas aeruginosa biofilms on the coatings. The results showed that ES increased hydrophobicity (122֯ vs 90֯) and surface roughness (2 μm vs 1.2 μm) but reduced surface stiffness (200 MPa vs 10800 MPa) in comparison to spin-coated samples. ES-coatings had microbead/nanofiber morphology while spin-coated samples had micro/nanoporous structure. Importantly, an almost confluent layer of endothelial cells was observed on ES-coated samples after 4 days in contrast to spin-coated ones. Various blood experiments revealed both coatings were hemocompatible and there was no significant difference among ES and spin-coated samples. Furthermore, ES-coated samples showed significantly lower propensity for biofilm formation. In conclusion, in vitro results revealed potential of ES to engineer different coating properties including hemo/biocompatibility and biofilm resistance for cardiovascular implants applications.

Development of Mass-controlled Ion Beam through a Vacuum Electrospray Method

Development of Mass-controlled Ion Beam through a Vacuum Electrospray Method

Experimental and numerical investigation on the effect of core-shell microcapsule sizes on mechanical properties of microcapsule-based polymers

In this study, the effect of various microcapsule sizes on the mechanical properties of microcapsule-based polymeric materials was investigated using the finite element method and validated with experimental outcomes. Specimens containing 5wt. % of microcapsules were fabricated to calculate the elastic modulus, and maximum tensile stress, and to validate numerical results. To consider the error, five tests were performed for all samples, and results were reported on average. The average errors between the numerical outcomes and experimental results were 4.74% and 5.35% for maximum tensile stress and elastic modulus, respectively. The coaxial electrospraying method was used for synthesizing microcapsules made of alginate (shell) and epoxy (core). A scanning electron microscope (SEM) was used to calculate the diameter of the capsules. To develop an empirical model for the average microcapsule diameter (AMD) and carry out the optimization process, response surface methodology (RSM) with central composite design was used. Also, analysis of variance was employed to validate the accuracy of the model. The effects of three parameters, including voltage, needle size, and the distance between the tip of the needle to the collector, on average microcapsule diameter, were investigated. The empirical model was validated by a confirmation run, and the determined error (1.93%) between the predicted and experimental results indicates the precision of the model. The numerical study indicated that microcapsule-based self-healing polymers containing smaller microcapsules tolerate higher stresses. However, the effect of the microcapsules’ size on the elastic modulus of a representative volume element was negligible.

Oriented preparation of Large-Area uniform Cs2TeI6 perovskite film for high performance X-ray detector

Large-area flexible perovskite films are attracting widespread research interest for applications in wearable solar cells, portable photodetectors, bendable X-ray imaging detectors and other implantable optoelectronic devices. In this work, a facile mobile platform assisted electrospray method is developed to prepare large-area (100 cm2) lead-free Cs2TeI6 film on flexible polyimide substrate. The spraying parameters are coupled with the growth temperature to achieve a dynamic balance. The as-prepared film by optimized process shows high uniformity in grain size, thickness and X-ray response without pinholes and cracks. Moreover, oriented nucleation is more likely to occur on the flexible organic substrates for less growth stress and mismatch stress, leading to preferred (222) plane orientation. X-ray detectors prepared with the films exhibit a resistivity of 1.9 × 1011 Ω·cm, an X-ray sensitivity of 226.8 μC⋅Gyair-1⋅cm−2 and a transient response rise time as fast as 42 ms under 50 kV X-ray at an electrical field of 6.67 × 103 V·mm−1. The modified electrospray method shows great potential applications for large-area devices of radiography, solar cell and other optoelectronic devices.

Microfluidic electrospray generation of porous magnetic Janus reduced graphene oxide/carbon composite microspheres for versatile adsorption

HypothesisGraphene-based microparticles materials are broadly utilized in all sorts of fields owing to their outstanding properties. Despite great progress, the present graphene microparticles still face challenges in the aspects of size uniformity, motion flexibility, and tailorable surface chemistry, which limit their application in some specific fields, such as versatile adsorption. Hence, the development of novel graphene microparticles with the aforementioned characteristics is urgently required. ExperimentsWe presented a simple microfluidic electrospray strategy to generate magnetic Janus reduced graphene oxide/carbon (rGO/C) composite microspheres with a variety of unique features. Specifically, the microfluidic electrospray method endowed the obtaiend microspheres with sufficient size uniformity as well as magnetic responsive motion ability. Additionally, magnetic-mediated surface assembly of phase transition lysozyme (PTL) nanofilm on the microspheres rendered the deposited area hydrophilic while non-deposited area hydrophobic. FindingsSuch magnetic Janus rGO/C composite microspheres with regionalized wettability characteristics not only showed prominent performance in adsorbing organic liquids with high adsorption capacity and remarkable reusability but also displayed satisfying biocompatibility for the efficient uptake of bilirubin. More encouragingly, the microspheres could serve as adsorbents in a simulative hemoperfusion setup, which further demonstrated the clinical application potential of the magnetic Janus rGO/C microspheres. Thus, we anticipate that the obtained magnetic Janus rGO/C composite microspheres could show multifunctional properties toward water treatment and blood molecule cleaning.

Multilayer films of exfoliated 2D oxide nanosheets by electrospray deposition

The potential of the electrospray deposition technique as new method to make nanosheet-based multilayer films is evaluated. Densely packed nanosheet-based films with thicknesses of 1–20 nm with rms roughnesses of 2.1–2.4 nm were fabricated on samples of 1 cm2 size with a growth rate of 0.5 nm/min. Electrosprayed Ti0.87O2 nanosheet films were successfully used as oriented growth templates for 40 nm perovskite SrRuO3 thin films grown by pulsed laser deposition. The electrospray method provides a fast and easy alternative to the more commonly used Langmuir–Blodgett (LB) deposition method for nanosheet films.

Advances in Protein-Based Nanocarriers of Bioactive Compounds: From Microscopic Molecular Principles to Macroscopical Structural and Functional Attributes.

Many proteins can be used to fabricate nanocarriers for encapsulation, protection, and controlled release of nutraceuticals. This review examined the protein-based nanocarriers from microscopic molecular characteristics to the macroscopical structural and functional attributes. Structural, physical, and chemical properties of protein-based nanocarriers were introduced in detail. The spatial size, shape, water dispersibility, colloidal stability, etc. of protein-based nanocarriers were largely determined by the molecular physicochemical principles of protein. Different preparative techniques, including antisolvent precipitation, pH-driven, electrospray, and gelation methods, among others, can be used to fabricate different protein-based nanocarriers. Various modifications based on physical, chemical, and enzymatic approaches can be used to improve the functional performance of these nanocarriers. Protein is a natural resource with a wide range of sources, including plant, animal, and microbial, which are usually used to fabricate the nanocarriers. Protein-based nanocarriers have many advantages in aid of the application of bioactive ingredients to the medical, food, and cosmetic industries.

Synthesis of the Core/Shell Structure of Polycaprolactone@Curcumin-‎Gluten for Drug Delivery Applications

In this study, polycaprolactone (PCL) nanoparticles were effectively synthesized as novel drug delivery systems by the electrospray method. Curcumin (Cur) was selected as the model drug with further enhanced stability of its composition with gluten (GLU). The physical-chemical characterization, including FTIR, UV-vis, and thermal analysis of PCL@Cur-GLU nanocapsules, are explored. The in vitro release profiles described by Ritger–Peppas models were also investigated, showing sustained release for 15 h after a burst release within the first five hours.

Dissolution improvement of binary solid dispersions of erlotinib prepared by one-step electrospray method.

Erlotinib hydrochloride, a selective tyrosine kinase inhibitor approved for treatment of non-small cell lung cancer firstly. Erlotinib classified as class II drugs in the Biopharmaceutical Classification System (BCS), which characterized by low solubility and high permeability. The aim of this study was to enhance the dissolution rate of this drug. The binary solid dispersions of erlotinib: PVP prepared at different ratios (1:3, 1:5, and 1:8) by electrospray technique. The characterization of formulations performed using differential scanning calorimetery (DSC), Fourier transform infrared spectroscopy (FT-IR) and dissolution rate test. The dissolution results showed that the dissolution rate of erlotinib from binary solid dispersions improved in comparison to pure drug. FTIR spectrum results showed that all peaks of erlotinib functional groups are also observable in the prepared solid dispersions. The FTIR results demonstrated that there was no interaction between drug and polymer. DSC thermograms of the prepared solid dispersions showed no drug-related peak, which is probably related to reduced crystallinity and drug amorphization. Based on the obtained results, it can be concluded that the erlotinib solid dispersion systems displayed improved dissolution rate compared to the pure drug. This will likely lead to increased drug bioavailability.

Fabrication of semi‐flexible carbon quantum dots‐reinforced polypyrrole ( PPy / CQDs ) composite electrodes by hybrid electrospray deposition for high‐performance energy storage device

A carbon quantum dots-reinforced polypyrrole (PPy/CQDs) composite electrodes were prepared via the hybrid electrospray method. PPy/CQDs composite shows superior electrochemical performance with a specific capacity (Qg) of 174.21 C g−1 at 1 A g−1 in 3 M KOH aqueous electrolyte. An all-solid-state asymmetric supercapacitor (ASC) is composed of PPy/CQDs as a positive electrode and rGO as a negative electrode with PVA/KOH gel electrolyte, which exhibited the specific capacity (Qg) of 79.25 C g−1 at the current density of 1.5 A g−1 with an energy and power density of 26.44 Wh kg−1 and 18 090.82 W kg−1, respectively. An assembled PPy/CQDs//rGO device offers cyclic retention of about 76.8% at 15 A g−1 after 10 000 cycles. The above results confirmed that the as-prepared PPy/CQDs composite electrode is more suitable for high-performance-based semi-flexible supercapacitor application.

An approach to the induced reaction mechanism of the combustion of the nano-Al/PVDF composite particles

Highly reactive aluminum-fluorine composites with novel structures have attracted much attention in the past decades. However, there is not a specific mechanism to explain the combustion-supporting or inducing effect of F-polymer on aluminum powders. Herein, we present a systematic study of the induced reaction mechanism and propose a new elaboration. Two types of Nano-aluminum/Poly(vinylidene fluoride) (n-Al/PVDF) composites are fabricated via electrospray and mechanical mixing method, respectively. The electrospray sample excites a Pre-Ignition Reaction (PIR) between fluorine and the Al2O3 shell at a low temperature, and simultaneously the specific surface area, surface element state and alumina shell structure of aluminum powders change to some extent. However, the surface structure of the physical mixture does not change significantly in the same temperature range. On this basis, we studied the relationship between the change of surface structure and the enhanced combustion performance of aluminum in electrospray sample. The results show that the combustion-supporting effect of PVDF on aluminum powder should be attributed to the corrosion of the alumina shell and the loose structure of the PIR product.

Construction of omniphobic PVDF membranes for membrane distillation: Investigating the role of dimension, morphology, and coating technology of silica nanoparticles

Surface deposition of silica nanoparticles (SiNPs) is widely used for constructing omniphobic membranes for membrane distillation (MD) with an aim of creating hierarchical and reentrant textures. Herein, we report a comprehensive analysis of the effects of physical properties of SiNPs on membrane performance from the viewpoint of their dimensions and morphologies. An emerging fabrication technology, i.e., the electrospray method, was also investigated and systematically compared to the conventional solution deposition. SiNPs with spherical dimensions of 30 nm aggregated significantly in solution deposition process, forming a surface layer with uncontrollable defects and becoming vulnerable to inorganic fouling. While membranes utilizing SiNPs with a diameter of 200 nm showed severe pore blocking, which resulted in much lower operational fluxes. However, the fluxes could be improved by 20–50% using hollow mesoporous SiNPs, where the intrinsic cavities provided extra channels for vapor transport. More importantly, using a high-voltage electric field in the electrospray procedure resulted in a uniform distribution of SiNPs, thereby endowing an ideal membrane surface layer for a robust MD operation. The proposed study provides new insights into the effects of the physical properties of SiNPs, and shows the advantage of electrospray technology in fabricating defect-free MD membranes for sustainable applications.

Coaxial electrospray of uniform polylactide core-shell microparticles for long-acting contraceptive

Despite its high efficacy and good patient compliance, the only long-acting injectable (LAI) contraceptive currently available in the US, depot medroxyprogesterone acetate (DMPA), is limited by significant side effects and a delayed return to fertility for up to 10 months after its intended duration of action. To overcome these limitations, we sought to develop an injectable poly(D,l-lactide) (PLA) microparticle for sustained release of contraceptive hormone, etonogestrel (ENG). A one-step technique, coaxial electrospray method was applied to prepare uniform ENG loaded core-shell structured and slow-degrading PLA microparticles (ENG-cs-MPs) to provide release control while minimizing polymer content. By adjusting voltage, polymer concentration and flow rate of the coaxial jetting solution, the prepared ENG-cs-MPs exhibited uniformly small particle size with volume mean diameter of 14.7 ± 0.5 μm and a shell thickness of 2.5 ± 0.1 μm, high drug loading of ~54%, high encapsulation efficiency of ~99%, and initial 1-day burst release of just ~10%. Long-term in vitro release of ENG was continuous for more than 3 months without change of the shell structure in 6 months. In PK studies, ENG-cs-MPs achieved a steady and continuous drug release for approximately 3 months and then quickly tapered off within 3 weeks. Hence, ENG-cs-MPs prepared by the coaxial electrospray method may be useful as a LAI contraceptive with an improved PK profile relative to DMPA.

Ion mobility spectrometry-tandem mass spectrometry strategies for the on-line monitoring of a continuous microflow reaction

Continuous flow chemistry is an efficient, sustainable and green approach for chemical synthesis that surpasses some of the limitations of the traditional batch chemistry. Along with the multiple advantages of a flow reactor, it could be directly connected to the analytical techniques for on-line monitoring of a chemical reaction and ensure the quality by design. Here, we aim to use ion mobility, mass and tandem mass spectrometry (IMS-MS and MS/MS) for the on-line analysis of a pharmaceutically relevant chemical reaction. We carried out a model hetero-Diels Alder reaction in a microflow reactor directly connected to the IMS-MS and MS/MS using either electrospray or atmospheric pressure photo ionization methods. We were able to monitor the reaction mechanism of the Diels Alder reaction and structurally characterize the reaction product and synthesis side-products. The chosen approach enabled identification of two isomers of the main reaction product. A new strategy to annotate the ion mobility spectrum in the absence of standard molecules was introduced and tested for its validity. This was achieved by determining the survival yield of each isomer upon ion mobility separation and density functional theory calculations. This approach was verified by comparing the theoretically driven collision cross section values to the experimental data. In this paper, we demonstrated the potential of combined IMS-MS and MS/MS on-line analysis platform to investigate, monitor and characterize structural isomers in the millisecond time scale.

Fabrication of Cathode Catalyst Layer By Use of Multi-Nozzle Electrospray Method on Polymer Electrolyte Fuel Cells

We have been researching manufacturing methods of catalyst layers in order to improve the effective utilization rate of Pt in polymer electrolyte fuel cells. In our previous research1-3, we demonstrated experimentally that an electrospray (ES) method was able to make great progress in the interface formation between the electrolyte polymer ionomer and the Pt supported on carbon1,3 or conductive ceramics2, and that the immediate drying of the catalyst layer ink also greatly contributes to the improvement of Pt effectiveness. Since the ink droplets had already dried when these were deposited on the membrane, we proposed that the ink drying process can be reduced and that the cost of producing the catalyst layer is also greatly reduced. However, since the amount of catalyst applied is very small with a single nozzle, we also proposed that a multi-nozzle system is indispensable in order to adapt to the actual catalyst layer formation process.Therefore, we are jointly developing the ES manufacturing system with a multi-nozzle device (Fig. 1a) in a collaboration between the University of Yamanashi and Meiko Co., Ltd. We developed the first prototype machine, MES-Lab.α, for R & D, which features options such as nozzle material, multi-nozzle structure, coating treatment of nozzle tip, nozzle fixing adhesive, suck-back method, and ink energization method, among others. We have completed a new design for a basic 72-nozzle block (Fig. 1b), which incorporates all of the above new materials and new structures and is compatible with the production of industry-standard electrodes (5 cm x 5 cm).The performance of the PEFC cell using the cathode catalyst layer produced by this ES device was superior to that of a cell using the conventional pulse-swirl-spray device (PSS). We prepared the catalyst layer according to two different ionization methods (positive (ESP), and negative (ESN) ionization), and compared these with that prepared by the PSS method.3 The catalyst layers prepared by ESN successfully mitigated oxygen transport resistance. The highest porosity, which induced better water management, revealed superior performance at high current. Moreover, we confirmed the importance of the proton conduction in the catalyst layer through the ionomer contents. Thinly coated ionomer film on the catalyst surface revealed that lower resistance originates from the ionomer film on the Pt surface, RCL, film , but poor σ H+cath. , as evaluated for low contents of ionomer in the catalyst layer. These results also suggest that we will be able to achieve superior actual cell performance for catalyst layers prepared via ES using modified ionomer chemical structures, for which there is enhanced H+ conductivity, σ H+cath. , via, e.g., increased ion exchange capacity, and oxygen permeability3 (Fig. 2). Acknowledgement This work was partially supported by funds for the “Superlative, stable, and scalable performance fuel cell” (SPer-FC) and the “Electrolytes, catalysts and catalyst layers with extraordinary efficiency, power and durability for PEFCs to 2030” (ECCEED’30-FC) projects from the New Energy and Industrial Technology Development Organization (NEDO) and the “Yamanashi Frontier for Innovation and Ecosystem” (FCyFINE) project from the Regional Innovation Ecosystems Program of the Ministry of Education, Culture, Sports, Science and Technology (MEXT). References Takahashi, K. Kakinuma, and M. Uchida, J. Electrochem. Soc., 163, F1182-F1188 (2016).Takahashi, R. Koda, K. Kakinuma, and M. Uchida, J. Electrochem. Soc., 164, F235-F242 (2017).Cho, K. Tamoto, and M. Uchida, Energy Fuels, 34, 14853−14863 (2020). Figure 1

Effect of the carboxyl functional group at the edges of graphene on the signal sensitivity of dopamine detection

Sensitive and selective detection of dopamine (DA) is important for the early diagnosis of diseases associated with abnormal DA levels. This study investigated the effect of the degree of carboxyl (−COOH) functional groups at the edges of graphene on the signal sensitivity of electrochemical DA detection in the presence of ascorbic acid (AA) and uric acid (UA). We prepared edge carboxylated graphene (ECG) nanoplatelets with a high proportion of oxygen functional groups (26.40%) and heat-treated ECG (HECG) with a low proportion of oxygen functional groups (2.35%), which were used to modify a fluorine-doped tin oxide (FTO) electrodes through the electrospray method. The ECG/FTO electrode showed excellent catalytic activity in separating AA, DA, and UA signals, potentially owing to the strong chemical interactions of these analytes with −COOH groups of ECG. While the HECG/FTO electrode displayed the oxidation signals suppression of AA and UA from those of DA signals with low sensitivity; this can be ascribed to decreased chemical interactions of these analytes with HECG induced by the low proportion of −COOH functional groups. Concurrently, the ECG/FTO sensor showed high sensitivity (ca. 2.11 μA/cm2/μM) and low detection limit (ca. 0.26 μM) for DA detection in the presence of AA and UA, while it was ca. 0.55 μA/cm2/μM and 1.0 μM, respectively, for the HECG/FTO sensor. These results suggest that the dense distribution of oxygen functional groups at the edges of graphene plays a vital role in ensuring high sensitivity and a low limit of DA detection.

Method and apparatus for forming electrode catalyst layer by electrospray method

The conversions of oxygenated compounds of bio-oils (alcohols, phenols and aromatic ethers) on a equilibrium FCC catalyst were studied at 500 °C during 60 s in a fixed bed laboratory reactor. Methanol, phenol and 2,6-dimethoxyphenol were dissolved in water and 1,2,4-trimethoxybenzene in benzene at 5 %wt. Identical experiments were performed over inert SiC. Conversions were very different, the highest one being that of 1,2,4-trimethoxybenzene (95.7 %wt.), followed by 2,6-dimethoxyphenol (75.0 %wt.), methanol (60.8 %wt.) and phenol (54.9 %wt.). Deoxygenation in all the reactants was from dehydration and decarboxylation. The highest yield of hydrocarbons (47.1 %wt.) and coke (16.0 %wt.) were from 1,2,4-trimethoxybenzene, which, together with methanol, yielded mainly aromatics in the gasoline range. On the contrary, phenol and syringol yielded C4-hydrocarbons with high content of olefins. The highest amounts of oxygenated compounds were produced by 2,6-dimethoxyphenol. The thermal conversions were similar to the catalytic ones in the only case of 1,2,4-trimethoxybenzene, but much lower with the other reactants. In comparison to the catalytic experiments, thermal tests yielded much more hydrocarbons with 1,2,4-trimethoxybenzene, and oxygenated compounds with 2,6-dimethoxyphenol, than the other reactants. These tests could help in the prediction of specific contributions by these reactants if bio-oils are co-processed in FCC units or upgraded over acidic catalysts.

Hierarchical Janus membrane via a sequential electrospray coating method with wetting and fouling resistance for membrane distillation

Membrane wetting and fouling issues are two major obstacles which hinder the practical application of membrane distillation (MD). In this study, a sequential electrospray method was introduced to impart a dual-layered superhydrophilic/superhydrophobic Janus skin onto a commercial polyvinylidene fluoride (PVDF) substrate. The bottom superhydrophobic layer was obtained by incorporating octaphenylsilsesquioxane (POSS) nanoparticles into PVDF carriers to construct a POSS@PVDF multiscale rough surface via electrospraying. At the same time, the top hierarchical-structured hydrophilic coating was composed of PAN beaded nanofilaments, rendering an intriguing in-air hydrophilicity and underwater superoleophobicity which benefited from the loose packing state of the interconnected beads and nanofibers. Further, this Janus skin exhibited good integrity and strong adhesion with the substrate, and due to its underlying superhydrophobicity and slightly decreased pore size, the hierarchical Janus membrane possessed a greatly enhanced liquid entry pressure of water (LEPw). Once applied in the MD process, with soybean-oil-in-saline-water emulsions as feed, this Janus membrane exhibited stable and excellent desalination performance with a high flux and nearly perfect salt rejection, whereas both the commercial and superhydrophobic membranes failed from oil contaminating. This suggests the remarkable simultaneous anti-wetting and anti-fouling property of Janus membranes, which possess great potential in water reclamation for challenging hypersaline oily wastewaters.

Corrosion inhibition of AA2024-T3 by a coating containing dual-pH sensitive, corrosion inhibitor loaded microspheres

In this study, we describe a smart coating that responds to either an increase or a decrease in pH to assist inhibitor effectiveness. Dual-pH sensitive microspheres containing a corrosion inhibitor were fabricated using a simple, template-free, one-step process. A polyelectrolyte coacervate consisting of polyacrylic acid and polyethylenimine was the shell material of microspheres that enclosed Ce(NO3)3 inhibitor using a coaxial electrospray method. The Ce(NO3)3-loaded microspheres with a core-shell structure can release Ce(NO3)3 at both acidic and alkaline pH. A smart coating consisting of these microspheres embedded in a polyvinyl butyral coating releases Ce(NO3)3 to improve the corrosion resistance of AA2024-T3.

Electrosprayed Collagen/Gentamicin nanoparticles coated microneedle patches for skin treatment

In this study, biocompatible microneedle patches were fabricated with three dimensional stereolithography (3D SLA) printer and coated with Gentamicin (GEN)-loaded Collagen (COL) nanoparticles fabricated with the electrospray method. The SEM results of the microneedles and COL/GEN nanoparticles coated microneedles showed that the nanosized microneedles were fabricated successfully, and these microneedles were coated with 1% COL/GEN solutions homogeneously. The release profiles of the GEN from the 1% COL/GEN nanoparticles coated microneedles reported that the drug was completely released within 540 min.