Size and molecular weight determination of polysaccharides by means of nano electrospray gas-phase electrophoretic mobility molecular analysis (nES GEMMA)

Particulate bioaerogels for respiratory drug delivery

The bioaerogel microparticles have been recently developed for respiratory drug delivery and attract fast increasing interests. These highly porous microparticles have ultralow density and hence possess much reduced aerodynamic diameter, which favour them with greatly enhanced dispersibility and improved aerosolisation behaviour. The adjustable particle geometric dimensions by varying preparation methods and controlling operation parameters make it possible to fabricate bioaerogel microparticles with accurate sizes for efficient delivery to the targeted regions of respiratory tract (i.e. intranasal and pulmonary). Additionally, the technical process can provide bioaerogel microparticles with the opportunities of accommodating polar, weak polar and non-polar drugs at sufficient amount to satisfy clinical needs, and the adsorbed drugs are primarily in the amorphous form that potentially can facilitate drug dissolution and improve bioavailability. Finally, the nature of biopolymers can further offer additional advantageous characteristics of improved mucoadhesion, sustained drug release and subsequently elongated time for continuous treatment on-site. These fascinating features strongly support bioaerogel microparticles to become a novel platform for effective delivery of a wide range of drugs to the targeted respiratory regions, with increased drug residence time on-site, sustained drug release, constant treatment for local and systemic diseases and anticipated better-quality of therapeutic effects.

The regulatory effect of polysaccharides on the gut microbiota and their effect on human health: A review

Polysaccharides with low toxicity and high biological activities are a kind of biological macromolecule. Recently, growing studies have confirmed that polysaccharides could improve obesity, diabetes, tumors, inflammatory bowel disease, hyperlipidemia, diarrhea, and liver-related diseases by changing the intestinal micro-environment. Moreover, polysaccharides could promote human health by regulating gut microbiota, enhancing production of short-chain fatty acids (SCFAs), improving intestinal mucosal barrier, regulating lipid metabolism, and activating specific signaling pathways. Notably, the biological activities of polysaccharides are closely related to their molecular weight, monosaccharide composition, glycosidic bond types, and regulation of gut microbiota. The intestinal microbiota can secrete glycoside hydrolases, lyases, and esterases to break down polysaccharides chains and generate monosaccharides, thereby promoting their absorption and utilization. The degradation of polysaccharides can produce SCFAs, further regulating the proportion of gut microbiota and achieving the effect of preventing and treating various diseases. This review aims to summarize the latest studies: 1) effect of polysaccharides structures on intestinal flora; 2) regulatory effect of polysaccharides on gut microbiota; 3) effects of polysaccharides on gut microbe-mediated diseases; 4) regulation of gut microbiota on polysaccharides metabolism. The findings are expected to provide important information for the development of polysaccharides and the treatment of diseases.

Lacticaseibacillus rhamnosus dfa1 Attenuate Cecal Ligation-Induced Systemic Inflammation through the Interference in Gut Dysbiosis, Leaky Gut, and Enterocytic Cell Energy

Despite an uncommon condition, the clinical management of phlegmon appendicitis (retention of the intra-abdominal appendiceal abscess) is still controversial, and probiotics might be partly helpful. Then, the retained ligated cecal appendage (without gut obstruction) with or without oral Lacticaseibacillus rhamnosus dfa1 (started at 4 days prior to the surgery) was used as a representative model. At 5 days post-surgery, the cecal-ligated mice demonstrated weight loss, soft stool, gut barrier defect (leaky gut using FITC-dextran assay), fecal dysbiosis (increased Proteobacteria with reduced bacterial diversity), bacteremia, elevated serum cytokines, and spleen apoptosis without kidney and liver damage. Interestingly, the probiotics attenuated disease severity as indicated by stool consistency index, FITC-dextran assay, serum cytokines, spleen apoptosis, fecal microbiota analysis (reduced Proteobacteria), and mortality. Additionally, impacts of anti-inflammatory substances from culture media of the probiotics were demonstrated by attenuation of starvation injury in the Caco-2 enterocyte cell line as indicated by transepithelial electrical resistance (TEER), inflammatory markers (supernatant IL-8 with gene expression of TLR4 and NF-κB), cell energy status (extracellular flux analysis), and the reactive oxygen species (malondialdehyde). In conclusion, gut dysbiosis and leaky-gut-induced systemic inflammation might be helpful clinical parameters for patients with phlegmon appendicitis. Additionally, the leaky gut might be attenuated by some beneficial molecules from probiotics.

Atmospheric Pressure Mass Spectrometry of Single Viruses and Nanoparticles by Nanoelectromechanical Systems

Mass spectrometry of intact nanoparticles and viruses can serve as a potent characterization tool for material science and biophysics. Inaccessible by widespread commercial techniques, the mass of single nanoparticles and viruses (>10MDa) can be readily measured by nanoelectromechanical systems (NEMS)-based mass spectrometry, where charged and isolated analyte particles are generated by electrospray ionization (ESI) in air and transported onto the NEMS resonator for capture and detection. However, the applicability of NEMS as a practical solution is hindered by their miniscule surface area, which results in poor limit-of-detection and low capture efficiency values. Another hindrance is the necessity to house the NEMS inside complex vacuum systems, which is required in part to focus analytes toward the miniscule detection surface of the NEMS. Here, we overcome both limitations by integrating an ion lens onto the NEMS chip. The ion lens is composed of a polymer layer, which charges up by receiving part of the ions incoming from the ESI tip and consequently starts to focus the analytes toward an open window aligned with the active area of the NEMS electrostatically. With this integrated system, we have detected the mass of gold and polystyrene nanoparticles under ambient conditions and with two orders-of-magnitude improvement in capture efficiency compared to the state-of-the-art. We then applied this technology to obtain the mass spectrum of SARS-CoV-2 and BoHV-1 virions. With the increase in analytical throughput, the simplicity of the overall setup, and the operation capability under ambient conditions, the technique demonstrates that NEMS mass spectrometry can be deployed for mass detection of engineered nanoparticles and biological samples efficiently.

Adeno-associated Virus Virus-like Particle Characterization via Orthogonal Methods: Nanoelectrospray Differential Mobility Analysis, Asymmetric Flow Field-Flow Fractionation, and Atomic Force Microscopy

Adeno-associated virus (AAV)-based virus-like particles (VLPs) are thriving vectors of choice in the biopharmaceutical field of gene therapy. Here, a method to investigate purified AAV serotype 8 (AAV8) batches via a nanoelectrospray gas-phase mobility molecular analyzer (nES GEMMA), also known as an nES differential mobility analyzer, is presented. Indeed, due to AAV's double-digit nanometer scale, nES GEMMA is an excellently suited technique to determine the surface-dry particle size termed electrophoretic mobility diameter of such VLPs in their native state at atmospheric pressure and with particle-number-based detection. Moreover, asymmetric flow field-flow fractionation (AF4, also known as AFFFF) and atomic force microscopy (AFM) techniques were employed as orthogonal techniques for VLP characterization. In addition, AF4 was implemented to size-separate as well as to enrich and collect fractions of AAV8 VLPs after inducing analyte aggregation in the liquid phase. Bionanoparticle aggregation was achieved by a combination of heat and shear stress. These fractions were later analyzed with nES GEMMA (in the gas phase) and AFM (on a solid surface). Both techniques confirm the presence of dimers, trimers, and putative VLP oligomers. Last, AFM reveals even larger AAV8 VLP aggregates, which were not detectable by nES GEMMA because their heterogeneity combined with low abundance was below the limit of detection of the instrument. Hence, the combination of the employed orthogonal sizing methods with the separation technique AF4 allow a comprehensive characterization of AAV8 VLPs applied as vectors.

Online hyphenation of size-exclusion chromatography and gas-phase electrophoresis facilitates the characterization of protein aggregates

Gas-phase electrophoresis yields size distributions of polydisperse, aerosolized analytes based on electrophoretic principles. Nanometer-sized, surface-dry, single-charged particles are separated in a high laminar sheath flow of particle-free air and an orthogonal tunable electric field. Additionally, nano Electrospray Gas-Phase Electrophoretic Mobility Molecular Analyzer (nES GEMMA) data are particle-number based. Therefore, small particles can be detected next to larger ones without a bias, for example, native proteins next to their aggregates. Analyte transition from the liquid to the gas phase is a method inherent prerequisite. In this context, nonvolatile sample buffers influence results. In the worst case, the (bio-)nanoparticle signal is lost due to an increased baseline and unspecific clustering of nonvolatile components. We present a novel online hyphenation of liquid chromatography and gas-phase electrophoresis, coupling a size-exclusion chromatography (SEC) column to an advanced nES GEMMA. Via this novel approach, it is possible to (i) separate analyte multimers already present in liquid phase from aggregates formed during the nES process, (ii) differentiate liquid phase and spray-induced multimers, and (iii) to remove nonvolatile buffer components online before SEC-nES GEMMA analysis. Due to these findings, SEC-nES GEMMA has the high potential to help to understand aggregation processes in biological buffers adding the benefit of actual size determination for noncovalent assemblies formed in solution. As detection and characterization of protein aggregation in large-scale pharmaceutical production or sizing of noncovalently bound proteins are findings directly related to technologically and biologically relevant situations, we proposed the presented method to be a valuable addition to LC-MS approaches.

Electrospray: More than just an ionization source

Electrospraying (ES) is a potential-driven process of liquid atomization, which is employed in the field of analytical chemistry, particularly as an ionization technique for mass spectrometric analyses of biomolecules. In this review, we demonstrate the extraordinary versatility of the electrospray by overviewing the specifics and advanced applications of ES-based processing of low molecular mass compounds, biomolecules, polymers, nanoparticles, and cells. Thus, under suitable experimental conditions, ES can be used as a powerful tool for highly controlled deposition of homogeneous films or various patterns, which may sometimes even be organized into 3D structures. We also emphasize its capacity to produce composite materials including encapsulation systems and polymeric fibers. Further, we present several other, less common ES-based applications. This review provides an insight into the remarkable potential of ES, which can be very useful in the designing of innovative and unique strategies.

Bipolar Corona Discharge-Based Charge Equilibration for Nano Electrospray Gas-Phase Electrophoretic Mobility Molecular Analysis of Bio- and Polymer Nanoparticles

Separation of polydisperse, single-charged analytes in the nanometer size range in a high laminar sheath flow of particle-free ambient air and a tunable electric field based on the respective particle electrophoretic mobility diameter (EMD) can be achieved via gas-phase electrophoresis. In order to transfer analytes from a volatile electrolyte solution to the gas-phase as a single-charged species, a nano electrospray (nES) process followed by drying of nanodroplets and charge conditioning reaching Boltzmann charge equilibrium is a necessary prerequisite. In the case of a so-called nES gas-phase electrophoretic mobility molecular analyzer (nES GEMMA, also known as nES differential mobility analyzer, nES DMA), charge equilibration is based on bionanoparticle interaction with a bipolar atmosphere induced, e.g., by a radioactive α-particle emitter like ²¹⁰Po. It was the aim of our investigation to examine whether such a radioactive source can be easily replaced in the same nES housing by a nonradioactive one, i.e., by an AC corona discharge unit. The latter would be significantly easier to handle when compared to radioactive material in laboratory day-to-day business, waste disposal, as well as regulatory confinements. Indeed, we were able to combine a standard nES unit of our nES GEMMA instrument with a commercially available AC corona discharge device in a novel setup via an adapter. Our results show that this replacement yields very good results for a number of chemically different nanoparticles, an exemplary protein, a noncovalent protein complex, a virus-like particle, a polymer, and a liposome sample, when compared to a ²¹⁰Po based bipolar charge equilibration device.

Precoating membranes with submicron super-fine powdered activated carbon after coagulation prevents transmembrane pressure rise: Straining and high adsorption capacity effects

Commercially available powdered activated carbon (PAC) with a median diameter of 12-42 μm was ground into 1 μm sized superfine PAC (SPAC) and 200 nm sized submicron SPAC (SSPAC) and investigated as a pretreatment material for the prevention of hydraulically irreversible membrane fouling during a submerged microfiltration (MF) process. Compared with PAC and SPAC, SSPAC has a high capacity for selective biopolymer adsorption, which is a characteristic found in natural organic matter and is commonly considered to be a major contributor to membrane fouling. Precoating the membrane surface with SSPAC during batch filtration further removes the biopolymers by straining them out. In lab-scale membrane filtration experiments, an increase in the transmembrane pressure (TMP) was almost completely prevented through a precoating with SSPAC based on its pulse dose after coagulation pretreatment. The precoated SSPAC formed a dense layer on the membrane preventing biopolymers from attaching to the membrane. Coagulation pretreatment enabled the precoated activated carbon to be rinsed off during hydraulic backwashing. The functionality of the membrane was thereby retained for a long-term operation. Precoating the membranes with SSPAC after coagulation is a promising way to control membrane fouling, and efficiently prevents an increase in the TMP because of the straining effect of the SSPAC and the high capacity of the SSPAC to adsorb any existing biopolymers.

Virus-like particle size and molecular weight/mass determination applying gas-phase electrophoresis (native nES GEMMA)

(Bio-)nanoparticle analysis employing a nano-electrospray gas-phase electrophoretic mobility molecular analyzer (native nES GEMMA) also known as nES differential mobility analyzer (nES DMA) is based on surface-dry analyte separation at ambient pressure. Based on electrophoretic principles, single-charged nanoparticles are separated according to their electrophoretic mobility diameter (EMD) corresponding to the particle size for spherical analytes. Subsequently, it is possible to correlate the (bio-)nanoparticle EMDs to their molecular weight (M_W) yielding a corresponding fitted curve for an investigated analyte class. Based on such a correlation, (bio-)nanoparticle M_W determination via its EMD within one analyte class is possible. Turning our attention to icosahedral, non-enveloped virus-like particles (VLPs), proteinaceous shells, we set up an EMD/M_W correlation. We employed native electrospray ionization mass spectrometry (native ESI MS) to obtain M_W values of investigated analytes, where possible, after extensive purification. We experienced difficulties in native ESI MS with time-of-flight (ToF) detection to determine M_W due to sample inherent characteristics, which was not the case for charge detection (CDMS). nES GEMMA exceeds CDMS in speed of analysis and is likewise less dependent on sample purity and homogeneity. Hence, gas-phase electrophoresis yields calculated M_W values in good approximation even when charge resolution was not obtained in native ESI ToF MS. Therefore, both methods-native nES GEMMA-based M_W determination via an analyte class inherent EMD/M_W correlation and native ESI MS-in the end relate (bio-)nanoparticle M_W values. However, they differ significantly in, e.g., ease of instrument operation, sample and analyte handling, or costs of instrumentation.

A facile quantification of hyaluronic acid and its crosslinking using gas-phase electrophoresis

We report a facile, high-resolution approach to quantitatively characterize hyaluronic acid (HA) and study its crosslinking reaction using electrospray-differential mobility analysis (ES-DMA). Mobility size distributions, number concentrations, molecular mass distributions, and polydispersity index of HAs were obtained successfully via a rapid analysis by ES-DMA (< 30 min). The limit of detection, the limit of quantification, and the precision of the mobility size measurement achieve 2.5 nm, 4.0 nm, and 0.3 nm, respectively. Size exclusion chromatography (SEC) was employed as an orthogonal approach, showing that the averaged molecular mass and polydispersity index of HA measured by ES-DMA were close to the results of SEC on a semi-quantitative basis. The 1,4-butanediol diglycidyl ether (BDDE)-induced crosslinking of HA was also able to be successfully characterized through a time-dependent study using ES-DMA, which has shown the promise of direct analysis of solution-based reactions. Both the extent and the rate of HA crosslinking (induced by BDDE) were proportional to reaction temperature and concentration ratio of HA to BDDE. The activation energy of the reaction-limited BDDE-induced crosslinking of HA was found to be ≈ 21 kJ/mol. The prototype study demonstrates ES-DMA as a new method for a rapid quantitative characterization of HA and its derivative product and providing a capability of real-time monitoring of the HA crosslinking during formulation process. Graphical abstract.