Bead Density Research Articles

Preparation and in vitro characterization of graphene oxide impregnated superporous hydrogel beads: an effective approach of gastro-retentive drug delivery system

ABSTRACT The remarkable properties of graphene oxide, a shining dynamo, opened new possibilities for delivering the drug. The present work aims to fabricate a graphene-based porous hydrogel system that fades its side effects and encourages its utilization as a drug carrier. Graphene oxide was impregnated in the polymeric matrix for gastro-retentive drug delivery. Porogen was added to create a superporous structure. The extrusion-dripping technique is used to fabricate low density, super porous, and floating hydrogel beads, which were considered a practical approach to target the drug in a controlled and sustained manner in the stomach. The fabricated graphene oxide impregnates superporous beads were characterized by physicochemical analysis, morphological parameters, PXRD, swelling study, drug-release pattern, and in-vitro floating ability. The homogenous nature of fabricated samples was analyzed by weight and size variation. Micrometric properties were estimated to calculate the density and flow ability of superporous beads. The stability and shelf life of prepared hydrogels were performed by accelerated stability analysis according to ICH guidelines. Doxorubicin was chosen as a model anticancer drug. The pi–pi stacking technique is responsible for a considerable loading of the drug onto graphene oxide (GO). However, the successful preparation of low-density graphene oxide impregnates superporous hydrogel beads shows excellent floating ability, thus making it a promising candidate for stomach targeting.

Adsorption of Chromium (III) and Chromium (VI) Ions from Aqueous Solution Using Chitosan-Clay Composite Materials.

In this work, biopolymer chitosan and natural clay were used to obtain composite materials. The overall aim of this study was to improve the properties (porosity, thermal stability and density) of pure chitosan beads by the addition of clay and to obtain a chitosan-based composite material for the adsorption of heavy metals from an aqueous solution, using Mongolian resources, and to study the adsorption mechanism. The natural clay was pre-treated with acid and heat to remove the impurities. The chitosan and pre-treated clay were mixed in different ratios (8:1, 8:2 and 8:3) for chemical processing to obtain a composite bead for the adsorption of chromium ions. The adsorption of Cr(III) and Cr(VI) was studied as a function of the solution pH, time, temperature, initial concentration of the chromium solution and mass of the composite bead. It was found that the composite bead obtained from the mixture of chitosan and treated clay with a mass ratio of 8:1 and 8:2 had the highest adsorption capacity (23.5 and 17.31 mg·g-1) for Cr(III) and Cr(VI), respectively, in the optimum conditions. The properties of the composite materials, prepared by mixing chitosan and clay with a ratio of 8:1 and 8:2, were investigated using XRD, SEM-EDS, BET and TG analysis. The adsorption mechanism was discussed based on the XPS analysis results. It was confirmed that the chromium ions were adsorbed in their original form, such as Cr(III) and Cr(VI), without undergoing oxidation or reduction reactions. Furthermore, Cr(III) and Cr(VI) were associated with the hydroxyl and amino groups of the composite beads during adsorption. The kinetic, thermodynamic and isothermal analysis of the adsorption process revealed that the interaction between the chitosan/clay composite bead and Cr(III) and Cr(VI) ions can be considered as a second-order endothermic reaction, as such the adsorption can be assessed using the Langmuir isotherm model. It was concluded that the composite bead could be used as an adsorbent for the removal of chromium ions.

Machine learning investigation of polylactic acid bead foam extrusion

AbstractThis study employs machine learning algorithms to analyze the bead foam extrusion process and to assess the impact of processing parameters, specifically focusing on their effects on bead foam density and melt pressure in under water granulation (UWG) for polylactic acid (PLA). These interrelated parameters, influenced by processing parameters such as temperature, screw speed, and blowing agent, possess challenges for traditional empirical methods to capture. The key factors that significantly impact the prediction of melt pressure in UWG are blowing agent, injector pressure, temperature in B‐extruder and die size. Likewise, essential parameters for predicting bead foam density comprise blowing agent, injector pressure, temperature in B‐extruder, die plate temperature, melt temperature in B‐extruder, and melt pressure in B‐extruder. Machine learning (ML) models were employed to forecast bead foam density and melt pressure in UWG using various processing parameters in PLA bead foam extrusion. The random forest model achieved a high coefficient of determination score of 0.96 for predicting melt pressure in UWG. Additionally, the decision tree model demonstrated effective predictions for bead density, with the score: 0.81. These ML models can be applied to diverse materials, leading to more sustainable, efficient processes for bead foam extrusion.

Understanding ADC variation by fat content effect using a dual-function MRI phantom

BackgroundA dual-function phantom designed to quantify the apparent diffusion coefficient (ADC) in different fat contents (FCs) and glass bead densities (GBDs) to simulate the human tissues has not been documented yet. We propose a dual-function phantom to quantify the FC and to measure the ADC at different FCs and different GBDs.MethodsA fat-containing diffusion phantom comprised by 30 glass-bead-containing fat-water emulsions consisting of six different FCs (0, 10, 20, 30, 40, and 50%) multiplied by five different GBDs (0, 0.1, 0.25, 0.5, and 1.0 g/50 mL). The FC and ADC were measured by the “iterative decomposition of water and fat with echo asymmetry and least squares estimation-IQ,” IDEAL-IQ, and single-shot echo-planar diffusion-weighted imaging, SS-EP-DWI, sequences, respectively. Linear regression analysis was used to evaluate the relationship among the fat fraction (FF) measured by IDEAL-IQ, GBD, and ADC.ResultsThe ADC was significantly, negatively, and linearly associated with the FF (the linear slope ranged from -0.005 to -0.017, R2 = 0.925 to 0.986, all p < 0.001). The slope of the linear relationship between the ADC and the FF, however, varied among different GBDs (the higher the GBD, the lower the slope). ADCs among emulsions across different GBDs and FFs were overlapped. Emulsions with low GBDs plus high FFs shared a same lower ADC range with those with median or high GBDs plus median or lower FFs.ConclusionsA novel dual-function phantom simulating the human tissues allowed to quantify the influence of FC and GBD on ADC.Relevance statementThe study developed an innovative dual-function MRI phantom to explore the impact of FC on ADC variation that can affect clinical results. The results revealed the superimposed effect on FF and GBD density on ADC measurements.Key points• A dual-function phantom made of glass bead density (GBD) and fat fraction (FF) emulsion has been developed.• Apparent diffusion coefficient (ADC) values are determined by GBD and FF.• The dual-function phantom showed the mutual ADC addition between FF and GBD.Graphical

Quantification and modeling of macroparticle-induced mechanical stress for varying shake flask cultivation conditions.

In biotechnological processes, filamentous microorganisms are known for their broad product spectrum and complex cellular morphology. Product formation and cellular morphology are often closely linked, requiring a well-defined level of mechanical stress to achieve high product concentrations. Macroparticles were added to shake flask cultures of the filamentous actinomycete Lentzea aerocolonigenes to find these optimal cultivation conditions. However, there is currently no model concept for the dependence of the strength and frequency of the bead-induced stress on the process parameters. Therefore, shake flask simulations were performed for combinations of bead size, bead concentration, bead density and shaking frequency. Contact analysis showed that the highest shear stresses were caused by bead-bottom contacts. Based on this, a newly generated characteristic parameter, the stress area ratio (SAR), was defined, which relates the bead wall shear and normal stresses to the total shear area. Comparison of the SAR with previous cultivation results revealed an optimum pattern for product concentration and mean product-to-biomass related yield coefficient. Thus, this model is a suitable tool for future optimization, comparison and scaling up of shear-sensitive microorganism cultivation. Finally, the simulation results were validated using high-speed recordings of the bead motion on the bottom of the shake flask.

Peridynamic mesh-free simulation of glass and metal beads column collapses

The density of the metal beads is almost 3 times the density of glass beads, and the rheological response is consequently different from glass beads by using the μ(I) rheology. In this study, the μ(I) rheology is first applied to simulate metal beads column collapse, which is implemented in Peridynamics to capture the transition from the fluid-like state to the solid-like state in the granular flow. To achieve this, flow response by the rheological parameters in the μ(I) rheology is extensively investigated by simulating glass beads column collapse. The numerical results are compared to the experimental measurements in terms of the free surface, velocity distribution, and the interface in the collision of two adjacent granular columns. It is found that the mobility of the granular material is significantly affected by static friction μs. The friction μ2 with high inertia in the rheology can affect the movements of free surface points in the simulations. Another parameter of a constant I0 in the rheology can reduce the material's mobility if its value is very small and large values show insignificant effects on the flow characteristics. The parameters of (μs, μ2, I0) = (0.36, 0.42, 0.01) in the rheology model can capture the free surface profiles in good agreement with the experimental measurements for the metal beads column collapse with different aspect ratios by using the numerical method.

Dynamic interactive characteristics between icicle growth and corona discharge on HVDC outdoor insulators during icing accretion

AbstractIn order to improve the stability and reliability of high voltage direct current (HVDC) transmission lines in cold regions, this article investigated the corona discharges and the icicle growth characteristics on outdoor insulators under DC voltages. The experiments were conducted at CIGELE laboratory at University of Quebec. The simulation model of corona discharges and the theoretical model of icicle growth were established. The dynamic process and interactive characteristics between the icicle growth and corona discharges under different HVDC voltages were obtained. The results showed that the discharge activity was strong and the cooling effect of ionic air was weak under negative DC voltage, resulting in a large number of bubbles inside the icicle. More negative ions were produced under negative DC voltage, which enhanced the polarisation of water droplets, leading to a greater density of ice beads outside the icicles. In addition, the longest icicles of each insulator under high humidity could bridge the shed gap. The accumulated charge and leakage current were higher under negative DC voltage, as well as the corona discharge at the top of the icicles lasted longer. Therefore, the negative DC corona discharge more significantly inhibited the growth of the icicle, resulting in a slower growth rate of the icicles.

STEEL enables high-resolution delineation of spatiotemporal transcriptomic data.

Advances in spatial transcriptomics enlarge the use of single cell technologies to unveil the expression landscape of the tissues with valuable spatial context. Here, we propose an unsupervised and manifold learning-based algorithm, Spatial Transcriptome based cEll typE cLustering (STEEL), which identifies domains from spatial transcriptome by clustering beads exhibiting both highly similar gene expression profiles and close spatial distance in the manner of graphs. Comprehensive evaluation of STEEL on spatial transcriptomic datasets from 10X Visium platform demonstrates that it not only achieves a high resolution to characterize fine structures of mouse brain but also enables the integration of multiple tissue slides individually analyzed into a larger one. STEEL outperforms previous methods to effectively distinguish different cell types/domains of various tissues on Slide-seq datasets, featuring in higher bead density but lower transcript detection efficiency. Application of STEEL on spatial transcriptomes of early-stage mouse embryos (E9.5-E12.5) successfully delineates a progressive development landscape of tissues from ectoderm, mesoderm and endoderm layers, and further profiles dynamic changes on cell differentiation in heart and other organs. With the advancement of spatial transcriptome technologies, our method will have great applicability on domain identification and gene expression atlas reconstruction.

Poly(vinyl alcohol)/modified porous starch gel beads for microbial preservation and reactivation: preparation, characterization and its wastewater treatment performance.

Poly(vinyl alcohol) (PVA)/modified porous starch (MPS) gel beads were prepared through in situ chemical cross-linking by incorporating with MPS, which was obtained by modifying porous starch (PS) with polyethyleneimine (PEI) and glutaraldehyde (GA). Addition of MPS could improve the storage modulus and the effective crosslinking density (ve) of the gel beads, and the mechanical properties were enhanced. The PVA-MPS gel beads were preserved as immobilized microbial carriers for 40 d and reactivated in wastewater. Scanning electron microscope (SEM) observations showed that the beads were highly porous and conducive for microorganism adhesion. The PVA-MPS gel beads were able to remove 97% of ammonia nitrogen and 80% of chemical oxygen demand (COD) after reactivation under all four preservation conditions. The abundance of Hydrogenophaga as denitrifying bacteria on PVA-MPS gel beads increased, with abundance of 8.44%, 5.55%, 8.90% and 9.48%, respectively. It proved that the carrier provided a partial hypoxic environment for microorganisms.

Effect of B&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;3&lt;/sub&gt; Content on Structure and Properties in High Refractive Index BaO-ZnO-TiO&lt;sub&gt;2&lt;/sub&gt;-SiO&lt;sub&gt;2&lt;/sub&gt; Glass System

In this paper, BaO-ZnO-TiO2-SiO2 is used as the research system of high refractive index glass, and IR, XRD and DTA are used to study the structure, thermal behavior, crystallization and chemical stability of different glasses when B2O3 gradually replaces SiO2. The results show that when B2O3 replaces SiO2, glass still has an amorphous structure, and the density of glass shows a decreasing trend with the increase of B2O3 content. With the increase of B2O3 content, the boron-oxygen tetrahedron gradually transforms into the boron-oxygen triangle, which makes the overall crystallization of the glass structure weaken. The results show that the density, refractive index and water resistance of glass beads without B2O3 are the best. With the increase of B2O3 content, the activation energy of crystallization decreases, the potential barrier to be overcome for crystallization decreases, as the same time the phenomenon of glass crystallization is obvious. Keywords:High refractive index glass; BaO-ZnO-TiO2-SiO2; Crystallization; Chemical stability

Phase Diagram Study of Catanionic Surfactants Using Dissipative Particle Dynamics.

Dissipative particle dynamics (DPD) simulations has been performed to study the phase transition of a mixture of cationic and anionic surfactants in an aqueous solution as a function of the total concentration in water and the relative ratio of surfactants. The impact of the relative difference between the tail lengths of the cationic and anionic surfactants on the phase diagram has been simulated by tuning the number of DPD beads in the simulation model. This research also discusses the impact of the frequently used values of the parameters associated with the harmonic bonds among the bonded DPD beads on the obtained self-assemblies. We find remarkable differences in the resultant self-assemblies based on different choices of harmonic bond parameters. The performed simulations show an enhanced spectrum of self-assemblies with augmented tail lengths and disparate harmonic bond parameters. The obtained self-assemblies are quite unique and can potentially be used in the future for various applications. We also compare the simulation results of the vesicle structures obtained by modeling the electrostatic interaction in the simulation among the charged beads by explicitly introducing charges with a long-range interaction with those obtained by tuning the implicit electrostatic interaction without the long-range interaction. The effects of the chain length of the model and the harmonic bond parameters on the internal density of DPD beads and stress profiles within the vesicles are examined closely. These results are a significant contribution to understanding the stability of the phases and tailoring of the desired vesicles.

Beaded electrospun polyvinylidene fluoride (PVDF) membranes for membrane distillation (MD)

A new class of PVDF-based membranes suitable for membrane distillation were prepared via electrospinning. The classical fiber morphology of PVDF electrospun membranes was changed to generate a beaded structure by tuning the solvent ratio and operating parameters during membrane fabrication. Results showed that by increasing the N, N-Dimethylacetamide (DMAC) to acetone ratio used to prepare the PVDF solution, PVDF micron-sized beads can be created within the fiber structure of the electrospun membrane. This is mainly ascribed to the lower saturated vapor pressure of the DMAC, which is slowing the polymer solidification rate, resulting in a fiber-to-bead morphology. An increase in the bead density induces an increase of the WCA of the resulting membrane (from 134° to 148°), with a concomitant reduction of the membrane thickness. Large bead-to-fiber ratios may be obtained by working with low PVDF concentration (17 wt%) but at the expense of membrane mechanical stability. The latter can be enhanced by increasing the PVDF solution concentration. The results show that simultaneous deployment of 17 and 25 wt% of PVDF solutions in a double-needle electrospinning device enables the fabrication of electrospun PVDF-beaded membranes with high hydrophobicity, low thickness and good mechanical stability for membrane distillation. The best membrane showed a 34% increase in membrane permeability and maintained a more stable water flux compared to a commercial PVDF membrane when filtering hypersaline solution in high-recovery direct contact membrane distillation. Thus beaded PVDF structured electrospun structures may represent a facile method to improve PVDF membrane performance in MD applications.

Mechanistic insight into impact of clay on compressive elasticity of poly(N-alkyl acrylamide)/Laponite-based nanocomposite cryo-beads

Relationship between formation pathway and Hertzian elasticity of poly(N-isopropylacrylamide-co‑sodium acrylate)/Laponite® XLG, P(NIPA-NaA)/LAP, based nanocomposite cryo-beads was evaluated. Millimeter-sized nanocomposite cryo-beads were prepared by combination of dropwise freezing into cryogenic liquid (DFLC) method with sedimentation cryogelation method. pH-sensitive 3D-templete was formed by conducting free-radical crosslinking cryopolymerization of NIPA and NaA in the presence of synthetic hectorite Laponite® XLG as inorganic crosslinker and N,N′-methylenebis(acrylamide) as chemical crosslinker. The effects of network template, ionic comonomer, inorganic clay incorporation, pH- and ionic strength of swelling medium on the swelling and elasticity were evaluated as a function of bead size. The deformability of swollen cryo-beads was investigated using Hertzian elasticity. The crosslink density and Hertz modulus of nanocomposite beads vary with the droplet size and the polymer spheres with low crosslink density tend to absorb more water. In DFLC method, the desired sphere size and swelling can be adjusted by selecting the needle size used for dripping. The swelling degree increased significantly as the size of nanocomposite cryo-beads increased. At a fixed swelling ratio, the cylindrical nanocomposite cryogels exhibited greater elastic moduli and crosslink density than that of spherical gels. Correlation of elastic modulus of cryo-beads with swelling and cross-linked polymer concentration predicted a higher scaling exponent than the classical estimate for swelling in good solvents. It was investigated how the presence of 30 mol% pH-sensitive anionic comonomer NaA in the structure of all nanocomposite gels affects their pH-dependent swelling behavior. At pH < 5.7, the gels exhibited a lower swelling ratio, whereas at pH > 6.6 they tended to swell and followed second-order swelling kinetics by Fickian diffusion. When pH of swelling medium was alternately changed, all gels exhibited a pH-switch and swelling rate was two times higher than shrinkage rate. By investigating the effect of KCl, NaCl and K2CO3 on the swelling of cryobeads, it was determined how the salt cation changes the electrostatic repulsion between network charges. Nanocomposite cryo-beads showed fast pH-responsiveness and immediately reabsorbed the water they lost due to pH change, therefore, they can be designed as drug release carriers by pH-switching modulation.

Gut transit rate in Atlantic salmon ( Salmo salar ) exposed to optimal and suboptimally high water temperatures

The gut transit rate of ingested feed in fish affects the utilization of dietary nutrients; however, the influence of water temperature, remains underexplored in Atlantic salmon (Salmo salar). The present study quantified the gut transit rate of four distinct regions of the gastrointestinal tract (stomach, pyloric caeca, small and large intestine) of post-smolt Atlantic salmon at two temperatures; 11 and 20°C, by feeding fish a diet incorporated with Ballotini beads. A determination of relative and total bead density in each region was assessed for 48 h, post-feeding. A clear inverse relationship in bead density between the stomach and large intestine was recorded at both temperatures. However, fish subjected to 20°C recorded a faster gut transit rate compared to fish at 11°C in both the stomach and large intestine. The pyloric caeca and small intestine transit rate appeared unaffected by temperature. The present study re-iterates the positive relationship between temperature and gut transit rate and also the critical function of the stomach in controlling gut transit rate in gastric fish. This information may be used to improve dietary strategies aimed at enhancing nutrient utilization through increased understanding of the gut transit rate in commercially important fish species.

Poly(vinylidene fluoride) electrospun nonwovens morphology: Prediction and optimization of the size and number of beads on fibers through response surface methodology and machine learning regressions

Electrospinning is one of the leading techniques for fiber development. Still, one of the biggest challenges of the technique is to control the nanofiber morphology without many trial-and-error tests. In this study, it is demonstrated that via design of experiments (DoE), response surface methodology (RSM) and machine learning regressions (MLR) it is possible to predict the beads-on-string size, size distribution and bead density in electrospun poly(vinylidene fluoride) (PVDF) mats with a small number of tests. PVDF concentration, dimethylacetamide/acetone ratio, tip-to-collector voltage and distance were the parameters considered for the design. The results show good agreement between the experimental and modeled data. It was found that concentration and solvent ratio play the main roles in minimizing bead size and number, distance tends to reduce them, and voltage does not play a significant role. As an evaluation of the potential of the method, bead-free fibers were obtained through the predicted parameter values. Comparison of the performance of the two methods is presented for the first time in electrospinning research. Response surface methodology resulted much faster, but MLR achieved a lower error and better generalization abilities. This approach and the availability of the MLR script used in this work may help other groups implement it in their research and find information hidden in the data while improving model prediction performance.

DEM study on effects of particle size and grinding media properties on energy transitions in a horizontal agitator

Thermal-mechanical cuttings cleaner, utilizing the energy dissipation of dense particle flow in the mill, is a type of low-temperature method for drying drill cuttings. In this paper, the energy dissipations of particle flow at the particle scale are simulated via discrete element method in a horizontal agitator. The effect of the particle diameter of sample particle and grinding media properties are considered in the simulation. The velocity distributions, contact force, input torque of the mill, and power dissipation of each component are employed to assess energy transitions. The results reveal that the contact force network in the bed is the main factor affecting the momentum transfer, and the motion and power dissipation are sharply promoted by the presence of grinding beads. The density of grinding beads has a significant effect on the permeability of grinding beads in sample particles and the consequent energy dissipation.

Glass beads retro-reflective coating for building application: albedo assessment in urban canyon configurations

Materials for urban pavements and building coatings have a direct impact on urban thermal environment: low-reflective and highly absorptive materials, in fact, could contribute to the exacerbation of the Urban Heat Island (UHI) phenomenon, which negatively affects building energy consumptions and indoor and outdoor thermal comfort. These effects could be worsened especially in Urban Heat Canyon configurations, where the inter-building effect becomes more relevant. As regards UHI mitigation strategies, high-reflective (HR) and retro- reflective (RR) materials have been studied for their application as urban coatings, in order to provide a cooling effect inside urban canyons. In this framework, this study aims at comparing the albedo performance of HR and RR materials applied on a small scale urban canyon facility. To this aim, an in-field experimental campaign was conducted in two days during summer 2020. Different canyon coating combinations and height/width (H/W) ratios were investigated and compared in terms of albedo. Results show that an albedo worsening occurs when the RR coating was applied to the canyon’s surfaces, because of the lower global reflectance of the RR with respect to the HR. Nevertheless, the application of RR coating on walls, coupled with HR paint on pavement, lead to higher albedo values of up to 4.7%, with respect to the opposite mixed coating combination. Future developments may concern the investigation of the optimum design of a glass bead RR material for building application, by studying the correlation between its optical capabilities and the dimensions and density of the glass beads.

Effects of Slip-Spring Parameters and Rouse Bead Density on Polymer Dynamics in Multichain Slip-Spring Simulations.

The multichain slip-spring (MCSS) model is one of the coarse-grained models of polymers developed in the niche between bead-spring models and tube type descriptions. In this model, polymers are represented by Rouse chains connected by virtual springs that temporally connect the chains, hop along the chain, and are constructed and annihilated at the chain ends. Earlier studies have shown that MCSS simulations can nicely reproduce entangled and unentangled polymer dynamics. However, the model parameters have been chosen arbitrarily, and their effects have not been reported. In this study, for the first time, we systematically investigated the effects of model parameters: fugacity of virtual springs, its intensity, and the Rouse bead density. We validated the employed simulation code by confirming that the statistics of the system follow the theoretical setup. Namely, the virtual spring density is correctly controlled, and polymer chains exhibit ideal chain statistics irrespective of the chosen parameter values. For diffusion and linear viscoelasticity, simulation results obtained for different parameters can be superposed with each other by conversion factors for the bead number per chain and units of length, time, and modulus. These conversion factors follow scaling laws concerning the number of Rouse segments between two consecutive anchoring points of virtual springs along the polymer chain. Besides, diffusion and viscoelasticity excellently agree with literature data for the standard bead-spring simulation. These results imply that the coarse-graining level for the MCSS model can be arbitrarily chosen and controlled by model parameters.

Evolution of “On-Barcode” Luminescence Oxygen Channeling Immunoassay by Exploring the Barcode Structure and the Assay System

The multiplexed luminescence oxygen channeling immunoassay (multi-LOCI) platform we developed recently that combines conventional LOCI and suspension array technology is capable of realizing facile “mix-and-measure” multiplexed assays without tedious washing steps. However, previous work lacks comprehensive studies of the structure–performance relationship of the host–guest-structured barcode, which may obstruct the evolution and further translation of this exciting new technology to practical applications. Accordingly, this work revealed that polyelectrolyte interlayers played a crucial role in tuning the packing density of guest acceptor beads (ABs). More interestingly, we noticed that “sparse” barcodes (barcodes with low ABs packing density) exhibited comparable assay performance with “compact” ones (barcodes with high ABs packing density). The high robustness of barcodes allows for multi-LOCI to be a more universal and flexible assay platform. Furthermore, through optimization of the assay system including the laser power, as well as the concentrations of donor beads and biotinylated detection antibodies, the multi-LOCI platform showed a significant improvement in sensitivity compared with our previous work, with the limit of detection decreasing to as low as ca. 1 pg/mL. Impressively, multi-LOCI that enabled simultaneous detection of multiple analytes exhibited comparable sensitivity with the classical single-plexed LOCI, due to the ingenious structural design of the multi-LOCI barcode and the unique “on-barcode” assay format.

Formalin-casein enhances water absorbency of calcium alginate beads and activity of encapsulated Metarhizium brunneum and Saccharomyces cerevisiae

The control of root-feeding wireworms has become more challenging as synthetic soil insecticides have been progressively phased out due to environmental risk concerns. Innovative microbial control alternatives such as the so-called attract-and-kill strategy depend on the rapid and successful development of dried encapsulated microorganisms, which is initiated by rehydration. Casein is a functional additive that is already used in food or pharmaceutical industry due to its water binding capacity. Cross-linked forms such as formalin-casein (FC), exhibit altered network structures. To determine whether FC influences the rehydration of alginate beads in order to increase the efficacy of an attract-and-kill formulation for wireworm pest control, we incorporated either casein or FC in different alginate/starch formulations. We investigated the porous properties of alginate/starch beads and subsequently evaluated the activities of the encapsulated entomopathogenic fungus Metarhizium brunneum and the CO2 producing yeast Saccharomyces cerevisiae. Adding caseins altered the porous structure of beads. FC decreased the bead density from (1.0197 ± 0.0008) g/mL to (1.0144 ± 0.0008) g/mL and the pore diameter by 31%. In contrast to casein, FC enhanced the water absorbency of alginate/starch beads by 40%. Furthermore, incorporating FC quadrupled the spore density on beads containing M. brunneum and S. cerevisiae, and simultaneous venting increased the spore density even by a factor of 18. Moreover, FC increased the total CO2 produced by M. brunneum and S. cerevisiae by 29%. Thus, our findings suggest that rehydration is enhanced by larger capillaries, resulting in an increased water absorption capacity. Our data further suggest that gas exchange is improved by FC. Therefore, our results indicate that FC enhances the fungal activity of both fungi M. brunneum and S. cerevisiae, presumably leading to an enhanced attract-and-kill efficacy for pest control.Graphic abstract