Electrospray Ionization Technique Research Articles

Development of magnesium hydroxide-doped nanofibrous spheres for repairing infected skin wounds

The healing of skin wounds is a continuous and coordinated process, typically accompanied by microbial colonization and growth. This may result in wound infection and subsequent delay in wound healing. Therefore, it is of particular importance to inhibit the growth of microorganisms in the wound environment. In this study, magnesium hydroxide-doped polycaprolactone (PCL/MH) nanofibrous spheres were fabricated by electrospinning and electrospray techniques to investigate their effects on infected wound healing. The prepared PCL/MH nanofibrous spheres had good porous structure and biocompatibility, providing a favorable environment for the delivery and proliferation of adipose stem cells. The incorporation of MH significantly enhanced the antimicrobial properties of the spheres, in particular, the inhibition of the growth of S. aureus and E. coli. We showed that such PCL/MH nanofibrous spheres had good antimicrobial properties and effectively promoted the regeneration of infected wound tissues, which provided a new idea for the clinical treatment of infected wounds.

Rapid analysis of the chemical constituents of traditional Tibetan medicine Sbyor-bzo-ghi-wang using ballpoint electrospray ionization technique.

The chemical constituents of traditional Tibetan medicines (TTM) can be identified using high-performance liquid chromatography and high-resolution mass spectrometry (HPLC-MS/MS) technique. However, the HPLC-MS/MS technique requires the sample to be pretreated and then separated using the specific liquid chromatography method, which is time consuming. This study developed a ballpoint electrospray ionization (BPESI) technique for analyzing the chemical constituents of Sbyor-bzo-ghi-wang. This technique is a simple and inexpensive method for the rapid identification of the chemical constituents of TTMs. After the important parameters of the homemade BPESI device were optimized, the chemical constituents of Sbyor-bzo-ghi-wang were quickly identified without sample pretreatment. The raw data were converted to mzML file using MSConvert and then identified using SIRIUS 5 software. The results showed that 30 compounds were identified from Sbyor-bzo-ghi-wang, namely eight bile acids, six flavonoids, four alkaloids, three amino acids, and nine others. Compared to the ultra-high-performance liquid chromatography-Q/Orbitrap and high-resolution mass spectrometry (UHPLC-Q/Orbitrap HRMS) technique, the BPESI technique identified almost similar types of compounds and also a comparable number of compounds. Compared with the traditional HPLC-MS/MS methods, the BPESI technique does not require complex sample pretreatment and subsequent chromatographic separation steps; also it consumes a small quantity of samples. Therefore, BPESI can be used for the qualitative analysis of the chemical constituents of Sbyor-bzo-ghi-wang.

Protein Nanoparticles Laden In situ Gel for Topical Ocular Drug Delivery.

Topical ocular delivery of drugs is most commonly preferred route by the patient and physician for the treatment of ocular diseases. The topical route is always followed with the disadvantages like tear turnover, nasolacrimal drainage, reduction in precorneal residence time, etc</i>. To overcome these hindrances associated with topical ocular route, a novel drug delivery system is used for targeting the drug at a specific site. In the Novel Drug delivery System, protein-based nanoparticles are an attractive class of nanoparticles designed to deliver the drug at targeted site in slow and sustained release manner. They have a size in the range of 1-100 nm. Protein nanoparticles are leading, particularly for the topical ocular delivery like reduction in intra ocular pressure, providing sustained release and targeted drug delivery at the site of its action. Various methods are used for formulation of protein nanoparticles like desolvation, emulsification, complex coacervation, electrospray techniques. The characterization parameters include particle size, surface morphology, drug loading and entrapment efficiency. Protein nanoparticles can also be loaded in to the in situ</i> gel forming polymers for increasing precorneal residence time of nanoparticles. The characterization parameters of in situ</i> gelling systems are gelling time, rheological properties, gel strength. The review mainly describes the use of various proteins in preparation of protein nanoparticles, methods for preparation of protein nanoparticles, polymers used in in situ</i> gelling system and evaluation as well as characterization parameters of protein nanoparticles, in situ</i> gelling systems & patented information related to protein nanoparticles and in situ</i> gelling system for ocular drug delivery.

Arc-Induced Electrospray Ionization Mass Spectrometry.

Arc-induced electrospray ionization mass spectrometry (AESI-MS) was developed during which alternating current electrospray is simply achieved through the arc plasma. The AESI source exploits the arc's temperature and charge properties to generate aerosols consisting of charged microdroplets. The electrospray region, in which organic molecules are contained within microdroplets, partially overlaps with the arc plasma region. Guided by the electric field, these molecules undergo ionization, yielding ionic target analytes. AESI represents a soft ionization method that combines the mechanisms of atmospheric pressure chemical ionization and electrospray ionization, facilitating the ionization of analytes with wide ranging polarities. The precisely targeted spraying area enhances ion entry into the mass analyzer, thereby enabling excellent ionization efficiency. The AESI source exhibits several notable advantages over the electrospray ionization source, including an elevated but comparable level of active species concentrations and types, simplified mass spectra for direct amino acid analysis, high salt tolerance, versatile analysis of compounds with varying polarities, and reliable quantitative analysis of amino acids in complex matrices. Overall, AESI broadens the methodologies employed to generate microdroplets, providing a technological and scientific framework for creating distinctive electrospray ionization techniques.

Alginate-Based Patch for Middle Ear Delivery of Probiotics: A Preliminary Study Using Electrospray and Electrospinning

Antimicrobial resistance poses a growing challenge in respiratory tract diseases like otitis media, often necessitating surgical interventions due to pharmacological treatment limitations. Bacteriotherapy, involving probiotics and/or their bioproducts, emerges as a promising alternative in such a scenario. This study aims to pave the way to middle ear bacteriotherapy by developing an innovative sodium alginate (SA)-based probiotic delivery system using electrospinning and electrospray techniques. Electrospray enabled the precise production of probiotic-laden SA microparticles, demonstrating potential for targeted bacterial delivery. By overcoming challenges due to the SA molecular structure, we successfully electrospun SA-based fiber meshes with poly(ethylene oxide) (PEO) as a support polymer. The rheologic behavior of the probiotic/SA solutions and the morphology of the obtained microparticles and fibers was evaluated, along with the diameter variation over time. The cytocompatibility of the produced microparticles and fibers was assessed using human dermal keratinocytes and their antimicrobial activity was tested against E. coli. The incorporation of probiotic-laden SA microparticles within electrospun SA/PEO fiber meshes finally offered a patch-like structure to be applied on the tympanic membrane or on the outer auditory canal, which could be a versatile and ideally safe treatment strategy in chronic otitis media. This innovative approach holds promise for clinical applications dealing with inflammatory processes, infections and dysbiosis, thus possibly addressing the complex healing process of chronic upper respiratory diseases while mitigating antimicrobial resistance.

A molecular study of viscosity-causing mechanism and viscosity reduction through re-emulsification for Jimsar shale oil

The high viscosity caused by oil–water emulsification and the lack of clarity on the viscosity-causing mechanism have seriously affected the development of Jimsar shale oil. In this paper, the mechanism behind the increase in viscosity due to emulsification for Jimsar shale oil is revealed at the molecular level, using high-resolution Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) coupled with Electrospray ionization (ESI) technique. The high amount of N1 compounds (carbazoles and indoles) in shale oil combine with water through the N–H bond with the pyridine ring adsorbing formation water, which enhances crude oil's emulsification and water-binding ability. A stable W/O emulsion was formed with water and significantly increased the viscosity of the formation fluid. DFT calculations showed that the interaction energy (Eint) of anionic surfactant AS-1 and AS-2 with polar macromolecules was −258.70 and −77.03 kcal/mol, respectively. The interaction energy of these two systems was much lower than that between H2O and polar macromolecules (-50.87 kcal/mol). It indicated that AS-1 and AS-2 could penetrate the oil–water interface and form stronger interactions with polar macromolecules. Thus, the W/O emulsion is in a reversed-phase, and the viscosity is reduced. The laboratory results showed that the viscosity reduction rates (VRR) of AS-1 and AS-2 due to re-emulsification were greater than 94% at 30℃. The O/AS-1/W and O/AS-2/W emulsions formed during re-emulsification have pseudoplastic fluid flow characteristics and are relatively stable. The emulsions also exhibit spontaneous destabilization and water separation properties, lowering the cost of oil–water separation of produced liquid. Through weak dipole–dipole interaction, CH-π type interaction, and some weak interactions (O∙∙∙N, O∙∙∙S, O∙∙∙H), AS-1 and AS-2 make the space between crude oil and emulsion components more open and inhibit the aggregation of polar macromolecules furthering the viscosity reduction effect.

Fabrication of amine-functionalized and multi-layered PAN-(TiO2)-gelatin nanofibrous wound dressing: In-vitro evaluation

The development of advanced multifunctional wound dressings remains a major challenge. Herein, a novel multilayer (ML) electrospun nanofibers (NFs) wound dressing based on diethylenetriamine (DETA) functionalized polyacrylonitrile (PAN), TiO2 nanoparticles (NPs) coating (Ct), and bioderived gelatin (Gel) was developed for potential applications in wound healing. The ML PAN-DETA-Ct-Gel membrane was developed by combining electrospinning, chemical functionalization, synthesis, and electrospray techniques, using a layer-by-layer method. The ML PAN-DETA-Ct-Gel membrane is comprised of an outer layer of PAN-DETA as a barrier to external microorganisms and structural support, an interlayer TiO2 NPs (Ct) as antibacterial function, and a contact layer (Gel) to improve biocompatibility and cell viability. The NFs membranes were characterized by scanning electron microscopy (SEM), surface profilometry, BET analysis, and water contact angle techniques to investigate their morphology, surface roughness, porosity, and wettability. The ML PAN-DETA-Ct-Gel wound dressing exhibited good surface roughness, porosity, and better wettability. Cell morphology, proliferation, and viability were determined using fibroblasts (3T3), and antibacterial assays were performed against six pathogens. The ML PAN-DETA-Ct-Gel NFs membrane showed good cell morphology, proliferation, viability, and antibacterial activity compared with other membranes. This new class of ML NFs membranes offers a multifunctional architecture with adequate biocompatibility, cell viability, and antibacterial activity.

Mass Spectral Imaging to Map Plant-Microbe Interactions.

Plant-microbe interactions are of rising interest in plant sustainability, biomass production, plant biology, and systems biology. These interactions have been a challenge to detect until recent advancements in mass spectrometry imaging. Plants and microbes interact in four main regions within the plant, the rhizosphere, endosphere, phyllosphere, and spermosphere. This mini review covers the challenges within investigations of plant and microbe interactions. We highlight the importance of sample preparation and comparisons among time-of-flight secondary ion mass spectroscopy (ToF-SIMS), matrix-assisted laser desorption/ionization (MALDI), laser desorption ionization (LDI/LDPI), and desorption electrospray ionization (DESI) techniques used for the analysis of these interactions. Using mass spectral imaging (MSI) to study plants and microbes offers advantages in understanding microbe and host interactions at the molecular level with single-cell and community communication information. More research utilizing MSI has emerged in the past several years. We first introduce the principles of major MSI techniques that have been employed in the research of microorganisms. An overview of proper sample preparation methods is offered as a prerequisite for successful MSI analysis. Traditionally, dried or cryogenically prepared, frozen samples have been used; however, they do not provide a true representation of the bacterial biofilms compared to living cell analysis and chemical imaging. New developments such as microfluidic devices that can be used under a vacuum are highly desirable for the application of MSI techniques, such as ToF-SIMS, because they have a subcellular spatial resolution to map and image plant and microbe interactions, including the potential to elucidate metabolic pathways and cell-to-cell interactions. Promising results due to recent MSI advancements in the past five years are selected and highlighted. The latest developments utilizing machine learning are captured as an important outlook for maximal output using MSI to study microorganisms.

Automated high-throughput characterization of microbial metabolites and species using array ballpoint electrospray ionization technique.

Microbial metabolites are widely used in agriculture, food, environment, and medicine. However, there is a lack of high-throughput, nonclogging, and simple methods for the identification of microbial metabolites and their subspecies using ambient mass spectrometry (MS). Here, we proposed a method for analyzing the microbial metabolites and identifying their species using the array ballpoint electrospray ionization (aBPESI) technique. The previously developed BPESI was combined with the array analysis technique to form a high-throughput analysis technique called aBPESI. The bacteria cultured on the plate medium were directly analyzed using MS with aBPESI. Principal component analysis-linear discriminant analysis (PCA-LDA)algorithm was used to analyze the different subspecies groups. The results showed that aBPESI was capable of completing a sample analysis within 30 s, and the level of metabolite detection was comparable to existing techniques. The accuracy of bacterial subspecies identification was 90% (Pseudomonas aeruginosa) and 100% (Serratia marcescens). A new high-throughput and robust MS technique aBPESI was proposed. It does not require sample pretreatment and greatly reduces the sample analysis time. aBPESI shows a strong ability in microbial analysis and is expected to be further applied in other research fields.

High-Throughput Ultra Performance Liquid Chromatography-Tandem Mass Spectrometry Method Validation for the Estimation of Atorvastatin and Active Metabolites in Human Plasma

A highly selective, sensitive, rugged, and rapid ultra high-performance liquid chromatography-tandem mass spectrometry method (UPLC-MS/MS) is optimized and validated for reliable quantification of atorvastatin (ATR) and its active metabolites, 2-hydroxy atorvastatin (2-ATR) and 4-hydroxy atorvastatin (4-ATR) in human plasma using atorvastatin-D5 (ATR-D5), 2-hydroxy atorvastatin-D5 (2-ATR-D5), and 4-hydroxy atorvastatin-D5 (4-ATR-D5) as deuterium-labeled internal standards (ISTDs), respectively. Isocratic mode chromatographic separation was used with a reverse-phase C18 Symmetry Shield (150 × 4.6 mm, 5.0 μm) column and a mobile phase of acetonitrile:2 mM ammonium formate (pH-3.0) [65:35%v/v] at a flow rate of 0.7 mL/min. Electrospray ionization technique with positive ion mode polarity was applied to achieve the best signal intensity and stable response. Solid-phase extraction by direct elution method was applied to extract the drugs from the plasma sample. The calibration curve range was validated from a concentration range of 0.500-250 ng/mL for ATR and 2-ATR and 0.200-20 ng/mL for 4-ATR. The within-batch and between-batch precision and accuracy were found to be consistent and reproducible for all the analytes across the validation. Extraction recoveries were >80% for all analytes and ISTDs. All peaks of analytes and the respective ISTDs were eluted within 5.2 min. In this validated method, selective multivariate analytical approaches were utilized such as best fit linearity range for different strength formulations, preventive measures for in vivo and ex vivo autodegradation of metabolites, and shorter analysis time. This validated method can be useful for challenging quantification of ATR and its active metabolites for therapeutic drug monitoring and in high-throughput clinical study sample analysis.

Preparation and evaluation of astaxanthin-loaded 2-hydroxypropyl-beta-cyclodextrin and Soluplus® nanoparticles based on electrospray technology.

Astaxanthin is a type of food-derived active ingredient with antioxidant, antidiabetic and non-toxicity functions, but its poor solubility and low bioavailability hinder further application in food industry. In the present study, through inclusion technologies, micellar solubilization and electrospray techniques, we prepared astaxanthin nanoparticles before optimizing the formulation to regulate the physical and chemical properties of micelles. We accomplished the preparation of astaxanthin nanoparticle delivery system based on single needle electrospray technology through use of 2-hydroxypropyl-β-cyclodextrin and Soluplus® to improveme the release behavior of the nanocarrier. Through this experiment, we successfully prepared astaxanthin nanoparticles with a particle size of approximately 80 nm, which was further verified with scanning electron microscopy and transmission electron microscopy. Furthermore, the encapsulation of astaxanthin molecules into the carrier nanoparticles was verified via the results of attenuated total reflectance intensity and X-ray powder diffraction techniques. The in vitro release behavior of astaxanthin nanoparticles was different in media that contained 0.5% Tween 80 (pH1.2, 4.5 and 6.8) buffer solution and distilled water. Also, we carried out a pharmacokinetic study of astaxanthin nanoparticles, in which it was observed that astaxanthin nanoparticle showed an effect of immediate release and significant improved bioavailability. 2-hydroxypropyl-β-cyclodextrin and Soluplus® were used in the present study as a hydrophilic nanocarrier that could provide a simple way of encapsulating natural function food with repsect to improving the solubility and bioavailability of poorly water-soluble ingredients. © 2023 Society of Chemical Industry.

Coated Blade Spray with a Barrier: Improving Negative Electrospray Ionization and Sample Preparation.

Substrate-based electrospray ionization (ESI) techniques like paper, wooden tip, plastic tip, and metal-needle-based spray suffer from corona discharge, high background noise, and unstable spray in negative ionization mode, especially for the analysis of complex biological matrices, such as blood and urine. Coated blade spray coupled with mass spectrometry (CBS-MS) combines solid-phase microextraction's (SPME) efficient sample clean-up and enrichment and ambient MS's fast analysis and has proven to be an appealing alternative tool for the fast screening of target analytes in complex matrices. This paper documents the development of a new CBS blade design that features a barrier at the far end of the ESI tip. The findings of this work show that the addition of this simple barrier enabled the total RSD% to be reduced to less than 10% for sample preparation, ionization, and the MS detection of several drugs of abuse in negative mode, without compensation using internal standards. The improved stability of ESI in negative mode was investigated by observing the ESI process with a microscope camera and testing via CBS-MS. The new design was applied for the analysis of three drugs of abuse in urine, with the calibration curve correlation coefficient (R2 ≥ 0.9997) being calculated without the use of internal standards. The overall RSD% of the peak area for one compound in 42 samples was 6.9%, which highlights the method's incredible reproducibility compared to other ambient MS techniques for analyzing real samples. The CBS device with a barrier was also applied for the on-blade sampling of 14 drugs of abuse in 20 μL of plasma spot in positive ionization mode. The results of these tests yielded a calibration curve correlation coefficient of R2 ≥ 0.9883 and limits of quantification (LOQs) between 0.25 and 25 ng/mL. The obtained results provide guidance on CBS device design optimization and the effective automation of the protocol.

Real-Time Sniffing Mass Spectrometry Aided by Venturi Self-Pumping Applicable to Gaseous and Solid Surface Analysis.

Based on the Venturi self-pumping effect, real-time sniffing with mass spectrometry (R-sniffing MS) is developed as a tool for direct and real-time mass spectrometric analysis of both gaseous and solid samples. It is capable of dual-mode operation in either gaseous or solid phase, with the corresponding techniques termed as Rg-sniffing MS and Rs-sniffing MS, respectively. In its gaseous mode, Rg-sniffing MS is capable of analyzing a gaseous mixture with response time (0.8-2.1 s rise time and 7.3-9.6 s fall time), spatial resolution (<80 μm), three-dimensional diffusion imaging, and aroma distribution imaging of red pepper. In its solid mode, an appropriate solvent droplet desorbs the sample from a solid surface, followed by the aspiration of the mixture using the Venturi self-pumping effect into the mass spectrometer, wherein it is ionized by a standard ion source. Compared with the desorption electrospray ionization (DESI) technique, Rs-sniffing MS demonstrated considerably improved limit of detection (LOD) values for arginine (0.07 μg/cm2 Rs-sniffing vs 1.47 μg/cm2 DESI), thymopentin (0.10 μg/cm2 vs 2.67 μg/cm2), and bacitracin (0.16 μg/cm2 vs 2.28 μg/cm2). Rs-sniffing is applicable for the detection of C60(OCH3)6Cl-, an intermediate in the methoxylation reaction involving C60Cl6 (solid) and methanol (liquid). The convenient and highly sensitive R-sniffing MS has a characteristic separation of desorption from the ionization process, in which the matrix atmosphere of desorption can be interfaced by a pipe channel and self-pumped by the Venturi effect with consequent integration using a standard ion source. The R-sniffing MS operates in a voltage-, heat-, and vibration-free environment, wherein the analyte is ionized by a standard ion source. Consequently, a wide range of samples can be analyzed simultaneously by the R-sniffing MS technique, regardless of their physical state.

Interaction of a natural compound nanoemulsion with Gram negative and Gram positive bacterial membrane; a mechanism based study using a microfluidic chip and DESI technique

The antibacterial activity of a nanoemulsion prepared from Satureja Khusitanica essential oil against a Gram-negative (Escherichia coli) and a Gram-positive (Bacillus atrophaeus) bacteria evaluated using microfluidic and conventional techniques. The effect of different residence time and concentrations on the antibacterial activity of nanoemulsion was studied by measuring the release of protein, nucleic acids, potassium, and also recording the MIC, MBC and time killing assays. Remarkable intensification was observed by employing microfluidic chip regarding a high-contact surface area between nanodroplets and bacterial membrane. The MIC and MBC values for E. coli and B. atrophaeus in conventional method were 400 and 1600 µg mL−1, respectively, whereas these values reduced to 11 to 50 µg mL−1 using microfluidic system. B. atrophaeus seemed to be more resistant than E. coli to the nanoemulsion treatment, perhaps due to different cell wall structures. Bacterial cell wall changes were examined using a desorption electrospray ionization (DESI) technique. It was found that the structural changes were more imminent in Gram negative E. coli by detecting a number of released lipids including phosphatidyl glycerol and phosphatidyl ethanolamines. The DESI spectra of B. atrophaeus revealed no M/Z related lipid release. These findings may help providing novel nano based natural antibacterials.

Photoelectron Circular Dichroism of Electrosprayed Gramicidin Anions.

Many sophisticated approaches for analyzing properties of chiral matter have been developed in recent years. But in general, the available chiroptical methods are limited to either solvated or small gaseous molecules. Studying the chirality of large biopolymers in the gas phase, including aspects of the secondary structure, becomes accessible by combining the electrospray ionization technique with chiroptical detection protocols. Here, laser-induced photodetachment from gramicidin anions, a peptide consisting of 15 amino acids has been investigated. The angular distribution of photoelectrons is demonstrated to be sensitive to the substitution of protons by cesium ions, which is accompanied by a conformational change. The photoelectron circular dichroism (PECD) is -0.5% for bare gramicidin, whereas gramicidin with several Cs+ ions attached exhibits a PECD of +0.5%. The results are complemented and supported by ion mobility studies. The presented approach offers the prospect of studying chirality and the secondary structure of various biopolymers.

Development and validation of a sensitive LCMS/MS method for the simultaneous quantification of Azelnidipine and Chlorthalidone in human plasma

Highly resolved, selective and sensitive liquid chromatography/tandem mass spectrometry (LC–MS/MS) method was optimised for the simultaneous quantification and recently approved combined medication for the treatment of hypertension viz. azelnidipine and chlorthalidone in spiked human plasma. The study utilizes nifedipine as internal standard. In the extraction of analytes from spiked plasma, acetonitrile was used to induce protein precipitation and then liquid – liquid extraction was carried using ethyl acetate solvent followed by the LCMS-MS analysis. The analytes were separated on Inertsil ODS C18 (4.6 mm×100 mm, 5 μm) column at room temperature with 65:35 (v/v) ratio of acetonitrile and 0.1% formic acid as the mobile phase at 0.5 mL/min flow rate. Detection was performed on a triple quadrupole mass spectrometer employing electrospray ionization technique, operating in multiple reaction monitoring with the transitions of m/z 583 → 331, 339 → 321 and 347 → 328 respectively for azelnidipine, chlorthalidone and nifedipine. The analytes were detected at a retention time of 1.72 min, 2.62 min and 3.12 min respectively for azelnidipine, chlorthalidone and nifedipine and the analysis was completed within run time of 5 min. The analysis was carried in the calibration range of 5-500 ng/mL with a very sensitive detection limit of 1.5 ng/mL. The method was validated as per FDA guidelines for bioanalytical method validation and the results in all the validation parameters were in the acceptable limit. Results proved that the method was selective, sensitive, accurate, precise and stable and hence can be applicable for the routine analysis of azelnidipine and chlorthalidone in biological samples.

Formation of disaggregated polymer microspheres by a novel method combining pulsed voltage electrospray and wet phase inversion techniques

Polymer microspheres with controlled sizes have attracted interest due to their potential use in medical field. Therefore it is of great importance to be able to produce a large number of disaggregated microspheres with a narrow diameter distribution. This work describes the successful elaboration of the method combining electrospray and wet phase inversion for the manufacturing of such polymer microspheres with mean diameters of 2 – 15 µm. Their recovery and drying are easy and they can be directly applied afterwards. The method is universal enough to produce microspheres from various polymers (polycaprolactone, polyethersulfone) and different solvents (dimethylformamide, N-methylpyrrolidone). It was noticed on the basis of microscopic images and using the nitrogen adsorption–desorption method that the specific surface of the microspheres differs depending on the polymer and solvent used. The work introduces additional parameters resulting from the use of pulsed voltage in the electrospray (pulse frequency f and duration τ) which results in better process control. As an example of the use of microspheres as drug carriers, they were loaded with rhodamine and its release was tested. Such microspheres could be dispersed in polymer solution and used in extrusion-based techniques (electrospinning, 3D printing) to form novel complex drug delivery systems.

Unveiling host–guest–solvent interactions in solution by identifying highly unstable host–guest configurations in thermal non-equilibrium gas phase

We propose a novel scheme of examining the host–guest–solvent interactions in solution from their gas phase structures. By adopting the permethylated β-cyclodextrin (perm β-CD)–protonated L-Lysine non-covalent complex as a prototypical system, we present the infrared multiple photon dissociation (IRMPD) spectrum of the gas phase complex produced by electrospray ionization technique. In order to elucidate the structure of perm β-CD)/LysH+ complex in the gas phase, we carry out quantum chemical calculations to assign the two strong peaks at 3,340 and 3,560 cm−1 in the IRMPD spectrum, finding that the carboxyl forms loose hydrogen bonding with the perm β-CD, whereas the ammonium group of L-Lysine is away from the perm β-CD unit. By simulating the structures of perm β-CD/H+/L-Lysine complex in solution using the supramolecule/continuum model, we find that the extremely unstable gas phase structure corresponds to the most stable conformer in solution.

Increasing DESI-MS Ion Signal by Plasma Treatment.

Many studies are focused on using plasma in mass spectrometry as an ionization source or postionization method. In this study, the effect of plasma treatment in the sample preparation step of desorption electrospray ionization (DESI) has been investigated. The plasma treatment of polar samples, including morphine, codeine, captopril, theophylline, fructose, and amphiphilic compounds such as phosphatidylethanolamine (PE) in E. coli bacteria, as well as nonpolar compounds, including thebaine, papaverine, and noscapine, has been followed for ionization efficiency in DESI technique. An atmospheric-pressure glow discharge plasma (GDP) along with the electrospray ionization technique is examined. Plasma treatment before ambient ionization has a dramatic effect on polar and nonpolar sample signals in DESI-TOF mass spectrometry. The intensity of the mass spectrum shows an increase of 1.9-3.4 times for polar compounds, 2.1-2.5 times for nonpolar compounds, and 3.0 times for PE in E. coli bacteria (N = 4). Plasma is a source of reactive atoms, molecules, ions, radicals, and ultraviolet radiation. Plasma surface treatment before DESI analysis by energetic species through momentum/energy transfer yields higher energy surface molecules, leading to more/easier desorption. Under optimal treatment conditions, an improved ion signal intensity is observed without any fragmentation, decomposition, or chemical changes. Ion signals are increased possibly by both increased ionization through protonation of molecules and enhanced subsequent desorption during DESI analysis.

A comprehensive review of electrospray technique for membrane development: Current status, challenges, and opportunities

In recent years, the electrospray (ES) technique has emerged as a novel method to fabricate or modify membranes used in separation processes. The ES technique has the potential to prepare three-dimensional (3D) membrane structures via precision-controlled layer-by-layer deposition, micro-/nano-droplet production, and in situ polymerisation. This review tracks the fundamentals and development of the ES technique and catalogues the features of membranes mainly in liquid phase pressure-driven and vapour phase thermally-driven separation processes prepared by this technique. The ES technique in cone-jet mode is classified into four stages to demonstrate the mechanisms. Based on the materials and membrane formation mechanisms involved, the state-of-the-art publications of the ES technique for membrane preparation are classified into four categories: ES for polymer delivery, ES-assisted monomer polymerisation, ES-assisted interfacial polymerisation, and ES for nanoparticle deposition. The knowledge gaps in each category are identified, with a key emphasis on the need to understand membrane formation mechanisms and the role of ES operating parameters to improve performance. Comparison of the ES technique with conventional membrane fabrication methods reveals the advantages of the ES technique, such as sustainable fabrication and production of three-dimensional, multi-layered, multi-material membrane structures and the limitations in reproducibility and scalability associated with the current state-of-the-art. Notwithstanding the current limitations, future perspectives are highlighted including utilising multiple ES configuration options, advancing ES techniques to realise 3D printing of membranes, accommodating novel materials for membrane fabrication, and exploring different types of substrates. • The developments of the ES technique and its applications in membrane are reviewed. • Various ES options and parameters can be further adapted to membrane development. • The ES technique is compared with conventional membrane making methods. • The challenges, research needs, and future perspectives are discussed.