Particulate Structures Research Articles

Enhancing mechanical and corrosion properties of GO and Al2O3 reinforced Cu composite coatings

Despite their significant functions and properties, the performance characteristics of Al2O3 ceramic particles and graphene oxide (GO) within hybrid copper composite coatings have been seldom investigated. This study successfully fabricated a Cu-GO- Al2O3 composite coating featuring fine particulate spherical network-like structures on St37 low carbon steel using an ultrasonic-electroless coating method. The effects of Al2O3-decorated graphene oxide hybrid reinforcement on the texture and nanomechanical properties of the copper matrix were examined. The tribological performance of the Cu-GO- Al2O3 composite coating under dry sliding conditions was evaluated, and the wear mechanism was investigated in detail. Results demonstrate that the Cu-GO- Al2O3 composite coating effectively reduces the wear rate and friction of the GO/ Al2O3 hybrid reinforced composite coating. Potentiodynamic polarization tests indicated that the Cu-GO- Al2O3 composite coating exhibits higher corrosion resistance compared to the copper matrix. The enhanced mechanical, tribological, and corrosion properties of the Cu-GO- Al2O3 composite coating are primarily attributed to: (i) the fine particulate spherical network-like structure; (ii) the synergistic effect of the GO and ceramic particle hybrid with a decorated structure; (iii) the formation of graphene oxide/ Al2O3 nanorolls in tribofilms and the excellent self-lubrication properties of graphene oxide. The Cu-GO- Al2O3 composite coating significantly improves the frictional and electrochemical properties of the copper matrix, offering new perspectives for next-generation electrical contacts and nanoelectromechanical systems.

3D-measurement of particles and particulate assemblies - A review of the paradigm shift in describing anisotropic particles

The goal of seeking advanced solutions to the descriptions of particle shape, packing and tomographic measurement were key areas promoted by Professor Reg Davies. In this paper we review and reflect on the revolution that has taken place over the last 30 years in our ability to describe and measure particle shape going beyond simple shape factors to their real morphologies of complex particles and particulate assemblies. The paper presents a comprehensive review of how shape has been described and some critical analyses in the form of extended tabulations. We show how digital approaches to particle descriptions can be used to predict the properties of particles and assemblies and their use in simulations of particle processing. We note the current status and prospects for the continued development of microtomographic systems to enable the measurement of particle shape in 3D and also the 3D imaging of complex particulate structures to enable property and processing predictions. Examples of these developments and critical appraisal of their utility will be given.

Water-Soluble and Freezable Aluminum Salt Vaccine Adjuvant.

Particulate aluminum salts have long occupied a central place worldwide as inexpensive immunostimulatory adjuvants that enable induction of protective immunity for vaccines. Despite their huge benefits and safety, the particulate structures of aluminum salts require transportation and storage at temperatures between 2 °C and 8 °C, and they all have exquisite sensitivity to damage caused by freezing. Here, we propose to solve the critical freezing vulnerability of particulate aluminum salt adjuvants by introducing soluble aluminum salts as adjuvants. The solubility properties of fresh and frozen aluminum chloride and aluminum triacetate, each buffered optimally with sodium acetate, were demonstrated with visual observations and with UV-vis scattering analyses. Two proteins, A244 gp120 and CRM197, adjuvanted either with soluble aluminum chloride or soluble aluminum triacetate, each buffered by sodium acetate at pH 6.5-7.4, elicited murine immune responses that were equivalent to those obtained with Alhydrogel®, a commercial particulate aluminum hydroxide adjuvant. The discovery of the adjuvanticity of soluble aluminum salts might require the creation of a new adjuvant mechanism for aluminum salts in general. However, soluble aluminum salts might provide a practical substitute for particulate aluminum salts as vaccine adjuvants, thereby avoiding the risk of inactivation of vaccines due to accidental freezing of aluminum salt particles.

Detachment of particulate structures from a fiber array due to stretching and simultaneous gas flow

The main cause of high pressure drop and increased energy consumption in a filtration process is the clogging of particulate material in the upstream layers of a depth filter. To alleviate this issue, stress can be introduced into the particulate structure through stretching, which promotes rearrangement and detachment of particle structures, allowing for transfer of some of the clogged particulate material from the upstream layers to downstream void regions. This study aims to extend previous findings from experiments with single fibers to the level of an array. The goal is to analyze the introduction of a multiple stress state by performing stretching experiments with a particle-structure on a fiber array.The stretching tests investigate the influence of different process parameters such as stretching velocity and air flow velocity during stretching on the rearrangement and detachment behavior of a separated particle structures from the fiber array. Rearrangement and detachment of the particle structure are a direct consequences of the stress induced by stretching. The experiments showed a significant increase in relative free projection area of fiber interspaces (RFPI) of up to 160% and thus a large-scale removal of particle material from the fiber interspaces when the flow velocity was increased from 0.05 m/s to 0.8 m/s. Surprisingly, the radial rearrangement of the compact particle structures during stretching resulted in a clogging and blockage of the interfiber spaces (negative RFPI in the range of minimum −54% after the first stretching cycle) and not in a total release of the interfiber spaces. The size of the particle structures in the experiments decreased by about 331 μm with the number of stretching cycles, indirectly confirming the presence of residual structures. Preliminary experiments also confirmed an increased influence on the rearrangement and detachment (removed pariticulater material of about 30%) of particle structures by further increasing the fiber distance of 27 μm and thus introducing a biaxial stretching into the particle structure.

Framework for the Generation of 3D Fiber Composite Structures from 2D Observations

Synthetic generation of realistic materials for testing of process–structure–property (PSP) relationships in computational materials science has gained significant traction over the past two decades. Generation tools continue to lag in some aspects of realism, leading to uncertainty and errors in simulating material response. The experimental collection of information to guide generation of 3D synthetic structures remains costly, time consuming, and challenging. These challenges are compounded by limitations of stereology, which permits estimation of 3D microstructural statistics from 2D observations under restrictive assumptions on constituent morphologies and size distributions and can be difficult to apply to microstructure metrics like constituent orientation distribution and clustering. This work seeks to overcome these challenges by introducing a framework for learning probable 3D microstructure statistics by minimizing the loss determined by matching statistics obtained from 2D observations via synthetic microstructure generation software (e.g. Dream.3D) and stereological principles. This framework is applied to short carbon fiber composite structures printed from an additive manufacturing process, Direct Ink Writing, with the hope that the framework could generalize to other particulate structures as well as allow for simulation and design of materials structure.

IRON DYNAMICS AND RISK OF IRON TOXICITY IN SOILS OF THE FOREST ZONE OF SOUTH-EASTERN COTE D'IVOIRE

In order to better understand the soils of the forest zone of the South-East of Côte d'Ivoire, four observation sites were identified at the Agropastorale B29 farm in the locality of Aboisso Comoé. These observations aimed in particular to quantify the different forms of iron in the soils, according to their depths and their topographical segments, in order to assess the risk of iron toxicity. For this purpose, soil pits were opened and described then soil samples were taken for laboratory analysis. The results obtained were compared to the reference values. They show that the soils are essentially Cambisols. They contain high levels of coarse manganiferric elements and clods, with polyhedral or particulate structures. They have a high concentration of free iron and total iron. Free iron is relatively more abundant in the surface horizons (0-20 cm) of the soil and in the topographic position of the lowlands. Thus, the free iron content is between 0.19% and 0.44%. A part of the free iron in the soil located on the surface of the soil where active surfaces such as clays and silts dominate, forms complexes with these particles and the other part is present in mobile forms in low topographical positions bottom. As for total iron, it is more concentrated at depth (60-120 cm), in the soils at the top and bottom of the slope with concentrations between 2.42% and 8.16%.

Perilipin2 depletion causes lipid droplet enlargement in the ovarian corpus luteum in mice.

Lipid droplets (LDs) are endoplasmic reticulum-derived organelles that store neutral lipids (mostly triglycerides and cholesterol esters) within a phospholipid monolayer and appear in most eukaryotic cells. Perilipins (PLINs, comprising PLIN1-5) are abundant LD-associated proteins with highly variable expression levels among tissues. Although PLINs are expressed in the mammalian ovaries, little is known about their subcellular localization and physiological functions. In this study, we investigated the localization of PLIN1-3 and their relationship with LD synthesis using mCherry-HPos reporter mice, thereby enabling the visualization of LD biogenesis in vivo. PLIN2 and PLIN3 were localized as puncta in granulosa cells with low levels of LD synthesis in developing follicles. This localization pattern was quite different from that of PLIN1, which was mainly localized in the theca and interstitial cells with high levels of LD synthesis. In the corpus luteum, where LD synthesis is highly induced, PLIN2 and PLIN3 are abundant in the particulate structures, whereas PLIN1 is poorly distributed. We also generated global Plin2-deficient mice using the CRSPR/Cas9 system and demonstrated that the lack of PLIN2 did not alter the distribution of PLIN1 and PLIN3 but unexpectedly induced LD enlargement in the corpus luteum. Collectively, our results suggest that the localization of PLIN1-3 is spatiotemporally regulated and that PLIN2 deficiency influences LD mobilization in the corpus luteum within the ovaries.

Unusual Shell Morphologies of Responsive Amino Core‐Shell Microgels Induced by pH During Shell Synthesis

AbstractThe properties of pH‐responsive microgels are strongly influenced by the pH value during synthesis. In this work, based on a N‐n‐propylacrylamide (NNPAM) core with N‐3‐(dimethylamino)propylmethacrylamide (DAPMA) as a comonomer, a series of core‐shell microgels with shells from NNPAM and N‐(3‐aminopropyl)methacrylamide hydrochloride (APMH) are synthesized at different pH values. While the swelling behavior is studied with temperature‐ and angle‐dependent photon correlation spectroscopy (PCS), the size and morphology are also investigated by means of atomic force microscopy (AFM) and static light scattering (SLS). At acidic pH, rather monodisperse microgels with a very fuzzy shell are obtained. The microgels evolve particulate structures on their shell at intermediate pH until not only a core‐shell microgel but also a secondary microgel species is produced at basic pH. By altering the synthesis pH, it is possible to influence the morphology of core‐shell microgels to suit future applications like the uptake and release of drugs or surface modification.

Conversion of liquid chitosan-based nanoemulsions into inhalable solid microparticles: Process challenges with polysaccharide

Solid particles ≤5 μm are essential to allow lower lung deposition and macrophage phagocytosis of anti-tubercular drugs. Decorating liquid nanoemulsion of anti-tubercular drug with macrophage-specific chitosan and chitosan-folate conjugate and spray drying the nanoemulsion with lactose produced oversized solid particles due to polysaccharide binding effects. This study designed solid nanoemulsion using lactose as the primary solid carrier and explored additives and spray-drying variables to reduce the binding and particle growth effects of chitosan. Deposition of magnesium stearate on lactose negated chitosan-inducible excessive lactose-liquid nanoemulsion binding and solid particle growth. Moderating the adhesion of chitosan-decorated liquid nanoemulsion onto lactose produced smooth-surface solid microparticles (size: 5.45 ± 0.26 μm; roughness: ∼80 nm) with heterogeneous size (span: 1.87 ± 1.21) through plasticization of constituent materials of nanoemulsion and lactose involving OH/N-H, C-H, CONH and/or COO moieties. Smaller solid particles could attach onto the larger particles with minimal steric hindrance by smooth surfaces. Together with round solid particulate structures (circularity: 0.919 ± 0.002), good pulmonary inhalation beneficial for treatment of pulmonary tuberculosis as well as other diseases is conferred.

Morphology of Particulate Structures on a Fiber Array before and at Clogging Point of an Aerosol Filtration Process

Fundamental microscopic investigations are based on the interaction between filter fiber and particles. The fibrous filter theory is based on a single fiber of a fiber array, and experiments focus either on a single fiber or a fiber array. This study investigates the particle loading process of a fiber array and focuses on the microscopic development of particle structures on the fiber array. Gravimetric measurements and image analysis of the array were used to study the development of the particle structure and morphology. Microscopic analysis of the video data focused on the evolution of particle accumulation within the fiber spacing, the development of boundary lines of the particle structure, and the number/size of bridges and pores within the particle structure. For the tested flow velocities, an increase in mass was observed to increase the duration of the filtration process. An extreme increase in deposited mass was observed at the moment of complete blocking (clogging) of the fiber spacing at flow velocities of 0.65 m/s. The size of pores (hydraulic diameter) increased with the flow velocity during the loading procedure. However, the total number of pores was higher in tests with lower Stokes numbers due to the dendritic and more porous structure. This work provides insights into the growth kinetics and structural setup of the particle structure (on a microscopic level). This will improve the understanding of the change of the filtration process from the transition phase to the clogging phase in fibrous filters.

Implicit modelling of complex particulate structures: The effect of particle packing on agglomerate strength

Understanding the mechanical behaviors of agglomerate structures is significant in the powder industry for various applications. In this paper, we used a novel Implicit Modelling method to create complex agglomerate structures with controlled structural parameters. Our focus is on the effect of particle packing on the mechanical property of agglomerates by designing two sets of agglomerate structures: random and segregated ones based on primary particle sizes. We used 3D printing to manufacture the agglomerate structures into multiple copies. Through static compression and Finite Element Analysis (FEA), the random agglomerates exhibited overall higher mechanical strength than the segregated ones with the same porosity level. The experimental and numerical methods showed a consistent quantitative analysis of different mechanical property indicators of pre-designed agglomerate structures. Meanwhile, the relationship between different structural parameters and their respective mechanical properties were developed. The results help broaden our understanding of the complex influential factors governing agglomerate strength.

Propensities of Fatty Acid-Modified ASOs: Self-Assembly vs Albumin Binding

We conducted a biophysical study to investigate the self-assembling and albumin-binding propensities of a series of fatty acid-modified locked nucleic acid (LNA) antisense oligonucleotide (ASO) gapmers specific to the MALAT1 gene. To this end, a series of biophysical techniques were applied using label-free ASOs that were covalently modified with saturated fatty acids (FAs) of varying length, branching, and 5'/3' attachment. Using analytical ultracentrifugation (AUC), we demonstrate that ASOs conjugated with fatty acids longer than C16 exhibit an increasing tendency to form self-assembled vesicular structures. The C16 to C24 conjugates interacted via the fatty acid chains with mouse and human serum albumin (MSA/HSA) to form stable adducts with near-linear correlation between FA-ASO hydrophobicity and binding strength to mouse albumin. This was not observed for the longer fatty acid chain ASO conjugates (>C24) under the experimental conditions applied. The longer FA-ASO however adopted self-assembled structures with increasing intrinsic stabilities proportional to the fatty acid chain length. For instance, FA chain lengths smaller than C24 readily formed self-assembled structures containing 2 (C16), 6 (C22, bis-C12), and 12 (C24) monomers, as measured by analytical ultracentrifugation (AUC). Incubation with albumin disrupted these supramolecular architectures to form FA-ASO/albumin complexes mostly with 2:1 stoichiometry and binding affinities in the low micromolar range, as determined by isothermal titration calorimetry (ITC) and analytical ultracentrifugation (AUC). Binding of FA-ASOs underwent a biphasic pattern for medium-length FA chain lengths (>C16) with an initial endothermic phase of particulate disruption, followed by an exothermic binding event to the albumin. Conversely, ASO modified with di-palmitic acid (C32) formed a strong, hexameric complex. This structure was not disrupted when incubated with albumin under conditions above the critical nanoparticle concentration (CNC; <0.4 μM). It is noteworthy that the interaction of parent, fatty acid-free malat1 ASO to albumin was below detectability by ITC (KD ≫150 μM). This work demonstrates that the nature of mono- vs multimeric structures of hydrophobically modified ASOs is governed by the hydrophobic effect. Consequently, supramolecular assembly to form particulate structures is a direct consequence of the fatty acid chain length. This provides opportunities to exploit the concept of hydrophobic modification to influence pharmacokinetics (PK) and biodistribution for ASOs in two ways: (1) binding of the FA-ASO to albumin as a carrier vehicle and (2) self-assembly resulting in albumin-inert, supramolecular architectures. Both concepts create opportunities to influence biodistribution, receptor interaction, uptake mechanism, and pharmacokinetics/pharmacodynamics (PK/PD) properties in vivo, potentially enabling access to extrahepatic tissues in sufficient concentration to treat disease.

The role of protein concentration in heat‐induced particulation of soy proteins at different pHs: Structure and functional properties

AbstractProtein particulation is a modification strategy for the optimization of the use of protein materials. The development and subtypes of particulate structures are largely dependent on the aggregated state of proteins after heat‐induced interactions, which is profoundly influenced by protein concentration (PC). In this work, the impact of PC below and above the critical gelation point, that is, 5% (w/v) and 10% (w/v), on the structure and functional properties of heat‐treated soy protein isolates (SPIs) at different pHs (2.0, 4.0, and 7.0), was investigated. The results showed that heat‐induced aggregation of SPIs was promoted by increasing the PC, leading to a β‐sheet‐dominated secondary structure. At pH 2.0 and 7.0, the 10% SPIs exhibited larger particle size and lower solubility, surface hydrophobicity index, and oil‐holding capacity compared to the 5% SPIs after heating. Furthermore, at neutral pH, the 10% SPI microgels had higher storage modulus (G′) and loss modulus (G″) than their acidifying counterparts, as well as the excellent emulsifying property for oil droplet stabilization. These findings would provide the theoretical basis for the structure modification and function improvement of plant proteins and, therefore, broaden the application of plant proteins in the food industry.

Preliminary evaluation of penile papule dermatoses with reflectance confocal microscopy in children.

Owing to their similar appearance, lichen striatus (LS), lichen nitidus (LN), juvenile xanthogranuloma (JXG), and molluscum contagiosum (MC) on the penis often lead to misdiagnosis and missed diagnosis, especially in children. In vivo evaluation of penile dermatoses with reflectance confocal microscopy (RCM) is helpful in the diagnosis of these ambiguous lesions in children. We recruited 12 patients with LS, nine with LN, seven with JXG, and nine with MC and evaluated the characteristics and distinguishing features of the four kinds of papule dermatoses on the penis using RCM. The four dermatoses all had unique RCM features. LS generally showed focally destroyed dermal papillary rings, with numerous mononuclear cell clusters aggregated inside the papillary rings, and highly refractive clumps were observed. For LN, the dermal papillary rings were completely destroyed and arranged in a solitary, enlarged, cavity-like structure, in which round cells, particulate matter structures, and plump cellular structures were aggregated; the adjacent skin was completely normal. In JXG, the dermal papillary rings were significantly dilated, and the superficial dermis was filled with different-sized large bright ring cells; smaller, refractive, roundish structures; and particulate matter. For MC, the normal structures completely disappeared; the lesions were arranged in a crater-shaped structure; and a mass-like substance formed by the aggregation of multiple, uniform, roundish structures was observed within the crater. RCM allows for real-time visualization of major key diagnostic and distinguishing features of four papule dermatoses, LS, LN, JXG, and MC, on the penis in children.

Numerical investigation of detachment and transport of particulate structures in wall-flow filters using lattice Boltzmann methods

The exhaust from combustion engines contains particulate matter (PM), which poses potential health risks to human lungs. Current emission laws place increasingly strict limitations on both PM and particle number, leading to the necessity of using wall-flow filters to separate out a significant amount of the introduced PM. As this leads to an increase in the filter's loading, it is regenerated continuously or periodically, leading to the rearrangement of individual particulate structures inside the filter channels. Such rearrangement events cause the formation of specific deposition patterns, which affect the filter's pressure drop, its loading capacity and the separation efficiency. In order to derive predictions on the formation of specific deposition patterns, the transient behaviour of individual particle structures needs to be examined. The present work investigates the detachment and transport of particle structures during filter regeneration with three-dimensional surface-resolved simulations using a lattice Boltzmann method. The goal of this work is the determination of relevant key quantities and their interpretation with respect to predictions regarding the resulting deposition patterns. In this context, it is shown that lift forces are not the predominant detachment forces for non-spherical particle structures, and that the stopping distance of such structures is too long to avoid back-end deposition.

Generation of multi-layered protein bodies in N. benthamiana for the encapsulation of vaccine antigens.

The ability of plants to assemble particulate structures such as virus-like particles and protein storage organelles allows the direct bioencapsulation of recombinant proteins during the manufacturing process, which holds promise for the development of new drug delivery vehicles. Storage organelles found in plants such as protein bodies (PBs) have been successfully used as tools for accumulation and encapsulation of recombinant proteins. The fusion of sequences derived from 27-kDa-γ-zein, a major storage protein of maize, with a protein of interest leads to the incorporation of the chimeric protein into the stable and protected environment inside newly induced PBs. While this procedure has proven successful for several, but not all recombinant proteins, the aim of this study was to refine the technology by using a combination of PB-forming proteins, thereby generating multi-layered protein assemblies in N. benthamiana. We used fluorescent proteins to demonstrate that up to three proteinaceous components can be incorporated into different layers. In addition to 27-kDa-γ-zein, which is essential for PB initiation, 16-kDa-γ-zein was identified as a key element to promote the incorporation of a third zein-component into the core of the PBs. We show that a vaccine antigen could be incorporated into the matrix of multi-layered PBs, and the protein microparticles were characterized by confocal and electron microscopy as well as flow cytometry. In future, this approach will enable the generation of designer PBs that serve as drug carriers and integrate multiple components that can be functionalized in different ways.

Synthesis of a crystalline zeolitic imidazole framework-8 nano-coating on single environment-sensitive viral particles for enhanced immune responses.

Encapsulating antigens with zeolitic imidazole framework-8 (ZIF-8) exhibits many advantages in vaccine development. However, most viral antigens with complex particulate structures are sensitive to pH or ionic strength, which cannot tolerate harsh synthesis conditions of ZIF-8. Balancing the viral integrity and the growth of ZIF-8 crystals is crucial for the successful encapsulation of these environment-sensitive antigens in ZIF-8. Here, we explored the synthesis of ZIF-8 on inactivated foot and mouth disease virus (known as 146S), which is easily disassociated into no immunogenic subunits under the existing ZIF-8 synthesis conditions. Our results showed that intact 146S could be encapsulated into ZIF-8 with high embedding efficiency by lowering the pH of the 2-MIM solution to 9.0. The size and morphology of 146S@ZIF-8 could be further optimized by increasing the amount of Zn2+ or adding cetyltrimethylammonium bromide (CTAB). 146S@ZIF-8 with a uniform diameter of about 49 nm could be synthesized by adding 0.01% CTAB, which was speculated to be composed of single 146S armored with nanometer-scale ZIF-8 crystal networks. Plenty of histidine on the 146S surface forms a unique His-Zn-MIM coordination in the near vicinity of 146S particles, which greatly increases the thermostability of 146S by about 5 °C, and the nano-scale ZIF-8 crystal coating exhibited extraordinary stability to resist EDTE-treatment. More importantly, the well-controlled size and morphology enabled 146S@ZIF-8(0.01% CTAB) to facilitate antigen uptake. The immunization of 146S@ZIF-8(4×Zn2+) or 146S@ZIF-8(0.01% CTAB) significantly enhanced the specific antibody titers and promoted the differentiation of memory T cells without adding another immunopotentiator. This study reported for the first time the strategy of the synthesis of crystalline ZIF-8 on an environment-sensitive antigen and demonstrated that the nano-size and appropriate morphology of ZIF-8 are crucial to exert adjuvant effects, thus expanding the application of MOFs in vaccine delivery.

Moonlighting in the matrix

The biofilm matrix is a complex, heterogeneous mixture of polymers, macromolecules, small molecules, and higher-order particulate structures. The primary functions of some matrix components are specific for building biofilms. However, there are many components of the biofilm matrix that have primary cellular functions yet provide additional distinct ‘moonlighting’ functions when located in the biofilm matrix. Moonlighting matrix components include proteins and nucleic acids as well as higher-order structures such as membranes and bacteriophage. This review will describe some of the moonlighting matrix components found in Pseudomonas aeruginosa biofilms.

The interplay of active and passive mechanisms in slow axonal transport

A combination of intermittent active movement of transient aggregates and a paused state that intervenes between periods of active transport has been proposed to underlie the slow, directed transport of soluble proteins in axons. A component of passive diffusion in the axoplasm may also contribute to slow axonal transport, although quantitative estimates of the relative contributions of diffusive and active movement in the slow transport of a soluble protein, and in particular how they might vary across developmental stages, are lacking. Here, we propose and study a model for slow axonal transport, addressing data from bleach recovery measurements on a small, soluble, protein, choline acetyltransferase, in thin axons of the lateral chordotonal (lch5) sensory neurons of Drosophila. Choline acetyltransferase is mainly present in soluble form in the axon and catalyzes the acetylation of choline at the synapse. It does not form particulate structures in axons and moves at rates characteristic of slow component b (≈ 1–10 mm/day or 0.01–0.1 μm/s). Using our model, which incorporates active transport with paused and/or diffusive states, we predict bleach recovery, transport rates, and cargo trajectories obtained through kymographs, comparing these with experimental observations at different developmental stages. We show that changes in the diffusive fraction of cargo during these developmental stages dominate bleach recovery and that a combination of active motion with a paused state alone cannot reproduce the data. We compared predictions of the model with results from photoactivation experiments. The importance of the diffusive state in reproducing the bleach recovery signal in the slow axonal transport of small soluble proteins is our central result.

Heat-induced gelation of protein from mealworm (Tenebrio molitor): influence of pH and zinc concentration

Mealworm protein has the general potential to substitute environmentally less favourable, animal derived raw-materials as a gelling biomaterial for zinc enriched wound healing ointments. However, various factors affecting heat-induced gelation of mealworm protein have not yet been studied in detail. Therefore, we investigated the influence of pH (pH 5.5 and 7.5) and zinc concentration (0 M, 0.1 M and 0.3 M) on rheological properties and gel structure of heat-induced mealworm protein gels. Additionally, we used gel solubility experiments and rheological investigations to study the gels with regard to the involved types of interactions. Generally, all examined samples were able to form heat-induced gels. From gel solubility experiments and temperature sweeps, hydrophobic interactions and hydrogen bonds were found to be dominant in all samples. From higher storage moduli we derive the contribution of additional electrostatic and/or covalent interactions in samples with ZnSO4, while shorter linear viscoelastic regimes and more pronounced intracycle strain stiffening were related to less homogenous and more particulate gel structures. From our results strategies for the customisation of gel properties and gel composition may be deduced, that may advance the potential for future utilisation of mealworm protein in wound dressings.