High Solute Concentrations Research Articles

Full biomass-derived multifunctional aerogel for solar-driven interfacial evaporation

Developing high-efficient utilization of thermal energy, excellent water transport path and mechanical stablility of biochar based solar-driven interfacial evaporator (SDIE) is critical for but still challenge. Herein, a three-dimensional network of porous scaffolds aerogel is prepared by cross-linking hydrophilic plantain cellulose (PC) and biomass hollow carbon tubes (HCTs) with excellent photothermal properties. The HCTs and PC winding with each other, the water adsorption by PC and desorption by HCTs which improve water evaporation. Under 1.0 sun illumination, the optimized PC@HCTs aerogel temperature on gas-liquid interface rapidly reach to 46.7 °C and the evaporation rate is 1.86 kg m−2h−1. In addition, PC@HCTs aerogel possess excellent water evaporation under high concentration of salt solutions and salt tolerance ability. Moreover, the PC@HCTs aerogel has obvious purification effect for seawater, heavy metal ion solution, oil-water emulsion and organic dye wastewater. Importantly, the dry PC@HCTs possesses excellent hardness while hyperelasticity in water. More importantly, the PC@HCTs aerogel with green recyclability which change the growth environment of sand and plants healthier, thus take materials from nature and final regress to nature. This work has the great scientific significance to promote the actual use of biochar based solar steam evaporators.

The potential of salinity gradient energy based on natural and anthropogenic resources in Sweden

This paper presents assessment of natural and anthropogenic sources of blue energy within Swedish territory to identify suitable spots for implementing new projects. The natural energy potential of salinity gradients was found to be higher in southwest Sweden, and a national energy resource potential of 2610.6 MW from seawater/river water mixing will be reduced to a technical potential ranging from 1044.3 MW to 1825.4 MW considering technical and environmental constraints. It has been found that the theoretical extractable energy potential in Sweden is equivalent to 13% of the total electricity consumption and 6.2% of the total final energy consumption by energy commodities.Anthropogenic water sources were also highlighted as promising low and high-concentration solutions for SGE extraction. Gotland was identified as an attractive location for generating salinity gradient power. The total salinity gradient power obtainable by mixing municipal wastewater with seawater in Sweden was estimated to be 11.8 MW. The most promising site for this process was determined to be Gryaab AB Ryaverket in Gothenburg, which accounted for 45.8% of the total national potential from anthropogenic sources.

Hofmeister effect induced advancement of the hydrogels by 3D printing

This study explores the cooperative effect of the Hofmeister phenomenon and three-dimensional (3D) printing in synthesizing high-strength hydrogels. We discovered that, when the printed hydrogels were exposed to a high salt concentration solution, the Hofmeister effect instigated robust and more compact interface interactions between the PHEMA/PVP covalent matrix and the gelatin. This significantly improved the mechanical attributes of the hydrogels. Upon comparison with the newly formed hydrogels, the tensile strength, fracture elongation, toughness, and modulus of the hydrogels subjected to the salting-out effect were amplified by factors of 20, 4, 110, and 70 respectively, thus demonstrating their exceptional mechanical performance. The study further reveals that the Hofmeister effect can augment the mechanical anisotropy of the printed hydrogels. In particular, Hofmeister ions trigger a reversible entanglement in the polymer chain. In this condition, adjacent filaments in a single printed layer of hydrogel display more densely entangled chains than the interior of the filaments, resulting in enhanced toughness in different orientations of the hydrogel. The approach described herein is not only applicable to current hydrogel materials but also can be extended to other printable hydrogel materials. By integrating 3D printing and the Hofmeister effect, we can customize the properties of hydrogels to satisfy specific requirements, facilitating the creation of advanced biomedical devices and applications.

Sustainable utilization of Sedum plumbizincicola as superior hydrochar for efficient nutrients recovery

To realize sound disposal of hyperaccumulator harvested from phytoremediation, hydrothermal carbonization (HTC) has been employed to obtain superior hydrochar adsorbents for removal of phosphate and ammonium from water body. A series of hydrochars have been prepared under tuned HTC conditions to tailor hydrochar with desired properties. Generally, increased temperature and prolonged reaction time facilitated acidic oxygen functional groups on hydrochars, thereby improving adsorption capacity of hydrochar. In single solute system, a superior hydrochar, derived from HTC under 260 °C for 2 h, achieved a maximum phosphate and ammonium adsorption capacity of 52.46 mg/g and 27.56 mg/g at 45 °C, respectively. In binary system, synergistic adsorption was observed only in lower solute concentration, whereas competitive adsorption occurred under higher solute concentration. Characterization and adsorption kinetics suggested chemisorption may dominate the adsorption process, thus the adsorption capacity could be improved by tuning pHpzc of hydrochar. This study firstly demonstrates the sustainable utilization of hyperaccumulators into nutrients-enriched hydrochar as fertilizer for in-situ phytoremediation of contaminated sites with minimized environmental risks towards circular economy.

Developing A Herbal Preservative For Cadavers In Ayurvedic Anatomy- A Pilot Study

Background: Preserving cadavers is crucial for anatomical studies, but traditional methods using chemicalssuch as formalin can have harmful properties. Ayurveda, like other sciences, lacks an alternative method forpreservation. This study aimed to find a safe and effective herbal preservative for cadavers.Aim: The aim of this study was to formulate an herbal preservative solution for human cadavers that ensuresno risk of infection on contact, preservation of the body, and prevention of putrefaction changes andcontamination with maggots and insects.Objective: The objectives of the study were to identify natural preservative ingredients used in Ayurveda,research individual ingredients for their possible role as preservatives, and prepare and test an herbal solutionon chicken muscle pieces.Material and Methods: A detailed literature survey was conducted to identify natural preservative ingredientsused in Ayurveda. The individual ingredients were researched for their possible role as preservatives. An herbalsolution was prepared using the identified ingredients, and its efficacy was tested on chicken muscle pieces.Results: The study identified natural preservative ingredients such as Amalaka, Vibhitaki, Haritaki, Neembaand Vidanga. These ingredients were found to have antimicrobial, antioxidant, and anti-inflammatoryproperties that could potentially preserve human cadavers. Tested herbal preservative solution on chickenmuscle pieces at different concentrations. Preservation duration increased with higher concentration ofsolution. Maximum preservation period was achieved with 100% solution with no signs of contamination withmaggots and insects.Conclusion: This study provides a potential alternative to traditional chemical embalming methods and mayenable Ayurvedic graduates to successfully practice medicine and surgery. To validate the effectiveness of theherbal solution on human cadavers, additional research is required. Moreover, in the main study, it isrecommended to substitute certain drugs that could potentially enhance tissue preservation longevity in thissolution.

Effect and mechanism of high Li2CO3 concentrations on the early hydration of sulfoaluminate cement-based materials

Lithium carbonate (Li2CO3) is a commonly used early strength agent for sulfoaluminate cement based grouting materials. Low concentrations of Li2CO3 (≤30 μmol Li/g in sulfoaluminate cement) can significantly accelerate the early hydration of sulfoaluminate cement. However, the effect of high Li2CO3 concentrations (>30 μmol Li/g in sulfoaluminate cement) on the early hydration of sulfoaluminate-cement-based materials (SCBMs) is unclear. In this study, the effects of high concentrations of lithium ion (Li+) and carbonate ion (CO32) on the early hydration of SCBMs (C4A3S¯–CaSO4–CaO) with different mineral compositions (systems T1 and T2) were investigated by hydration calorimetry, X-ray diffraction, and ion concentration measurements. The results revealed that both Li+ and CO32− promoted the hydration of C4A3S¯. Li+ and CO32− each reacted with aluminum and calcium in solution, and the formation of ettringite was suppressed when they were present. At low aluminum and high calcium concentrations in solution (system T1), ettringite formation was controlled mainly by the low concentration of aluminum. Less ettringite was generated, and the inhibition of ettringite formation by both Li+ and CO32− was weaker. At high concentrations of both aluminum and calcium in solution (system T2), ettringite formed more rapidly than in system T1, and Li+ and CO32− inhibited its formation to a greater extent. Li2CO3 affected the amount of ettringite by changing aluminum ion and calcium ion in slurry, thus leading to the change of hydration heat release. These new insights into the interaction between Li2CO3 and SCBMs contribute to the theoretical foundation for cement hydration control.

In-depth understanding of boosting salinity gradient power generation by ionic diode

Ionic diodes constructed with asymmetric channel geometry and/or charge layout have shown outstanding performance in ion transport manipulation and reverse electrodialysis (RED) energy collection, but the working mechanism is still indistinct. Herein, we systematically investigated RED energy conversion of straight nanochannel-based bipolar ionic diode by coupling the Poisson-Nernst-Planck and Navier-Strokes equations. The effects of nanochannel structure, charging polarity, and symmetricity as well as properties of working fluids on the output voltage and output power were investigated. The results show that as high-concentration feeding solution is applied, the bipolar ionic diode-based RED system gives higher output voltage and output power compared to the unipolar channel RED system. Under optimal conditions, the voltage output of the bipolar channel is increased by ∼100% and the power output is increased by ∼260%. This work opens a new route for the design and optimization of high-performance salinity energy harvester as well as for water desalination.

Process design of a thermochemical cycle for hydrogen production compatible with nuclear fusion heat sources

We quantitatively design a hydrogen-producing copper–chlorine thermochemical cycle that is thermally combinable with nuclear fusion reactors. The mass and heat balances throughout the cycle, including the hydrolysis, pyrolysis, and electrolysis reaction processes, accompanied by multiple separation steps, are numerically investigated. Through the process design, the feasibility of the practical operation of the hydrogen production cycle is presented, and the thermal and electric power required for the operation is evaluated. As we first design a process with straightforward employment of the exact reaction condition from an earlier experimental study of the electrolysis process, the heat required for the condensation of CuCl2 solution is found enormous. By modifying the process condition with an increased electrolyte concentration, to reduce the amount of H2O to be evaporated in the CuCl2 condensation, the total heat for the cycle significantly decreases from 1270 GJ·h−1 (20.3 MJ·mol-H2−1) to 204 GJ·h−1 (3.26 MJ·mol-H2−1). This value is still larger than the heat required for hydrogen production by H2O electrolysis, 48.2 GJ·h−1 (0.772 MJ·mol-H2−1), but an extrapolation towards the saturated CuCl concentration achieves 46.0 GJ·h−1 (0.736 MJ·mol-H2−1). For energy-cost performance improvement of the thermochemical cycle, the development of the electrolytic cell operable with a high concentration of CuCl aqueous solution is thus found to be of primary effectiveness.

Friction-induced rapid amorphization in a wear-resistant (CoCrNi)88Mo12 dual-phase medium-entropy alloy at cryogenic temperature

The CoCrNi medium-entropy alloy (MEA) has been proven to have excellent mechanical properties under cryogenic temperatures. Its low yield strength, however, limits practical application under harsh conditions, e.g., wear. Here, the (CoCrNi)88Mo12 dual-phase MEA, comprising a ductile face-centered cubic (FCC) matrix and a hard σ phase, was fabricated to strengthen the matrix and achieve excellent cryogenic wear performance. A significant wear reduction of 73% is achieved as the temperature decreases from 233 K to 113 K. It is found that the friction-induced amorphous layer underneath the worn surface contributes to excellent wear behaviors at 113 K, and amorphization would be rapidly occurred within 10 s. A lower stacking fault energy of CoCrNi-rich matrix at cryogenic temperature and a high solute concentration of Mo contribute to more defect accumulation and increased free energy of the system for amorphization. The current work clarifies the cryogenic wear mechanisms of the (CoCrNi)88Mo12 dual-phase MEA and provides a novel strategy for designing wear-resistant alloys via friction-induced rapid amorphization.

Zeolite performance in removal of multicomponent heavy metal contamination from wastewater

Efficient removal of heavy metal pollutants from wastewater by ion-exchange sorbents requires knowledge and understanding of the interplay between the adsorption patterns of the different components. The present study elucidates the simultaneous adsorption characteristics of six toxic heavy metal cations (Cd2+, Cr3+, Cu2+, Ni2+, Pb2+, and Zn2+) by two synthetic (13X and 4 A) and one natural (clinoptilolite) zeolite from solutions containing equimolar mixtures of the six metals. Equilibrium adsorption isotherms and equilibration dynamics were obtained by ICP-OES and complemented by EDXRF. An order of magnitude lower adsorption efficiency was exhibited by clinoptilolite (maximum of 0.12 mmol ions/g zeolite), relative to that obtained by the synthetic zeolites 13X and 4 A (a maximum of 2.9 and 1.65 mmol ions/g zeolite respectively). The strongest affinities to both zeolites were demonstrated by Pb2+ and Cr3+ (1.5 and 0.85 mmol/g zeolite respectively for 13X, and 0.8 and 0.4 mmol/g zeolite respectively for 4 A adsorbed from the highest solution concentration). The weakest affinities were observed by Cd2+ (0.1 mmol/g for both zeolites), Ni2+ (0.2 and 0.1 mmol/g for 13X and 4 A respectively), and Zn2+ (0.1 mmol/g for both zeolites). Large differences were observed between the two synthetic zeolites in terms of their equilibration dynamics and adsorption isotherms. Pronounced maxima were displayed in the adsorption isotherms for zeolites 13X and 4 A. The decline in adsorption of the weaker adsorbing ions with the increase in total solution concentration was attributed to the thermodynamic equilibrium between the ions adsorbed on the zeolite surface and those in the solution. Regeneration by 3 M KCL eluting solution resulted in considerable reduction in adsorption capacities following each desorption cycle.

F···Br and F···S Heterohalogen-Bond-Directed 2D Self-Assemblies of a Benzothiadiazole Derivative.

Halogen bonding (XB) is of great importance in fabricating a two-dimensional (2D) self-assembly for its adaptive directionality. However, the XBs involving fluorine (F) have barely been studied due to the absence of an σ-hole on F. Here, 2D self-assemblies of a F-substituted 4,7-bis(5-bromo-4-dodecylthiophen-2-yl)-5,6-difluorobenzo[c][1,2,5]thiadiazole (BTZ-BrF) molecule on graphite were investigated using scanning tunneling microscopy (STM) and density functional theory (DFT) calculations. STM experiments revealed that the 2D patterns of BTZ-BrF had a clear solvent and concentration dependence, showing a frame-like pattern in aliphatic acid and aliphatic hydrocarbon solvents at high concentrations. At lower concentrations, a bamboo-like and a wave-like pattern were observed in aliphatic acid, whereas small frame-like and large ladder-like domains at high solution concentrations in aliphatic hydrocarbon were observed. As the concentration further decreased, two linear patterns were observed. DFT calculations suggested that the hetero-XBs of F···Br, F···S, Br···S, and Br···N, the homo-XBs of type-II Br···Br, and the S···S interactions synergistically directed and stabilized the polymorphic 2D architectures. This understanding of intermolecular XBs during the molecular assembly at the molecular level may shed light on the ongoing efforts of regulating nanostructures of multifunctional organics.

Chromatographic purification of histidine-tagged proteins using zirconia particles modified with phosphate groups

Immobilized metal ion affinity chromatography (IMAC) is one of the most common purification techniques for histidine-tagged proteins (His-tagged proteins). IMAC enables the purification of His-tagged proteins at high purity on the basis of coordination bonds between His-tags and metal ions (such as Ni2+, Co2+, and Cu2+) immobilized on the matrices in columns. However, IMAC requires low-pH solutions or high-concentration imidazole solutions for eluting His-tagged proteins, which can affect protein conformation and activity. The present study provides a His-tagged protein purification method using zirconia particles modified with phosphate groups. This method is based on the electrostatic attractions between a His-tag moiety of proteins and phosphate groups on the zirconia particles; this method requires only high-concentration salt solutions at pH 7.0 for eluting the proteins. A column packed with phosphate-modified zirconia particles was demonstrated to enable the purification of two model His-tagged proteins—His-tagged green fluorescent protein and His-tagged alkaline phosphatase fused with maltose binding protein. Thus, this chromatography method is useful for purifying His-tagged proteins without any pH stress or additives. Additionally, because of the mechanical properties of the zirconia particles, this technique enables high-performance purification at a high flow rate.

Assessment of Dispersed Oil Sorption in Oily Wastewater onto Hydrophobized/Oleophilized Autoclaved Aerated Concrete (AAC) Grains

The discharge of untreated oily wastewater into the environment has serious impacts on human health, living nature, and ecosystems and leads to significant economic losses. Many engineering techniques have been proposed and applied to treat oily wastewater, but limited studies have investigated low-cost and effective techniques using by-products and waste/scrap materials from the construction industry. Materials to treat oily wastewater are needed not only to mitigate environmental pollution but also to promote the reuse and recycling of industrial by-products, especially in developing countries. This study, therefore, examined the sorption capacity of dispersed oil in wastewater (dispersed soybean oil in water; initial oil concentrations, Ci = 10–1000 mg/L; oil droplet size in water <2 μm) onto the hydrophobized/oleophilized autoclaved porous aerated concrete (AAC) grains made from waste scrap in Vietnam by using batch sorption tests in the laboratory. The AAC grains (sizes 0.106–0.25, 0.25–0.85, and 0.85–2.00 mm) were hydrophobized/oleophilized using oleic and stearic acids (coating concentrations of 1.0, 5.0, and 10 g/kg), and two sands (0.18–2.00 and 0.30–2.00 mm) were used as control samples. The results showed that the hydrophobized/oleophilized AAC grains had high sorption capacity for dispersed oil (i.e., high oil removal efficiency) compared to the control sands. Especially, the removal of AAC grains coated with stearic acid was >80% in high oil concentration solutions (Ci = 100 and 1000 mg/L), indicating that the hydrophobized/oleophilized AAC grains have high potential as useful adsorbents to trap dispersed oil in oily wastewater. Moreover, adsorption isotherms were drawn to examine the sorption characteristics of dispersed oil onto AAC grains. For all tested samples, the sorption of dispersed oil increased linearly with increasing equilibrium concentration. The commonly used Langmuir model, on the other hand, did not capture the measured isotherms.

Aerosolization Performance of Immunoglobulin G by Jet and Mesh Nebulizers

Recently, many preclinical and clinical studies have been conducted on the delivery of therapeutic antibodies to the lungs using nebulizers, but standard treatment guidelines have not yet been established. Our objective was to compare nebulization performance according to the low temperature and concentration of immunoglobulin G (IgG) solutions in different types of nebulizers, and to evaluate the stability of IgG aerosols and the amount delivered to the lungs. The output rate of the mesh nebulizers decreased according to the low temperature and high concentration of IgG solution, whereas the jet nebulizer was unaffected by the temperature and concentration of IgG. An impedance change of the piezoelectric vibrating element in the mesh nebulizers was observed because of the lower temperature and higher viscosity of IgG solution. This affected the resonance frequency of the piezoelectric element and lowered the output rate of the mesh nebulizers. Aggregation assays using a fluorescent probe revealed aggregates in IgG aerosols from all nebulizers. The delivered dose of IgG to the lungs in mice was highest at 95 ng/mL in the jet nebulizer with the smallest droplet size. Evaluation of the performance of IgG solution delivered to the lungs by three types of nebulizers could provide valuable parameter information for determination on dose of therapeutic antibody by nebulizers.Graphical abstract

Implication of hydrolysis on vanadium precipitation with acidic ammonium salt from high concentration of alkaline vanadium solution

Implication of hydrolysis on vanadium precipitation with acidic ammonium salt from high concentration of alkaline vanadium solution

Recovery of transition metal ions with simultaneous power generation by reverse electrodialysis

Renewable energy processes based on salinity gradient differences possess spreading interests as an alternative to energy production methods based on fossil fuels. The reverse electrodialysis (RED) process is used for energy production by mixing seawater and river water. In the proposed solution, the spent battery effluent is applied as a high-concentrated solution for the first time, generating a potential difference in the RED stack. The high-selective cation exchange membrane for cobalt transportation in the RED system was a demanding barrier controlling the separation behaviour. The initial research confirmed the energy production ability from mixing high concentrated (HC) solution of Co2+, Li+ and Ni2+ nitrates and low concentrated (LC) solution containing chloric acid. The maximum extracted energy was estimated at 0.44 W/m2 with an energy efficiency of 45.5%. The presented method is a promising candidate for dealing with battery waste management and converting it into a valuable product such as cobalt salts with the potential for power harvesting.

Raman Spectroscopic Analysis of Highly-Concentrated Antibodies under the Acid-Treated Conditions

PurposeAntibody drugs are usually formulated as highly-concentrated solutions, which would easily generate aggregates, resulting in loss of efficacy. Although low pH increases the colloidal dispersion of antibodies, acid denaturation can be an issue. Therefore, knowing the physical properties at low pH under high concentration conditions is important.MethodsRaman spectroscopy was used to investigate pH-induced conformational changes of antibodies at 50 mg/ml. Experiments in pH 3 to 7 were performed for human serum IgG and recombinant rituximab.ResultsWe detected the evident changes at pH 3 in Tyr and Trp bands, which are the sensitive markers of intermolecular interactions. Thermal transition analysis over the pH range demonstrated that the thermal transition temperature (Tm) was highest at pH 3. Acid-treated and neutralized one showed higher Tm than that of pH 7, indicating that their extent of intermolecular interactions correlated with the Tm values. Onset temperature was clearly different between concentrated and diluted samples. Colloidal analyses confirmed the findings of the Raman analysis.ConclusionOur studies demonstrated the positive correlation between Raman analysis and colloidal information, validating as a method for evaluating antibody conformation associated with aggregation propensities.

Two-dimensional separation of water-soluble polymers using size exclusion and reversed phase chromatography employing capillary-channeled polymer fiber columns

Polymeric materials are readily available, durable materials that have piqued the interest of many diverse fields, ranging from biomedical engineering to construction. The physiochemical properties of a polymer dictate the behavior and function, where large polydispersity among polymer properties can lead to problems; however, current polymer analysis methods often only report results for one particular property. Two-dimensional liquid chromatography (2DLC) applications have become increasingly popular due to the ability to implement two chromatographic modalities in one platform, meaning the ability to simultaneously address multiple physiochemical aspects of a polymer sample, such as functional group content and molar mass. The work presented employs size exclusion chromatography (SEC) and reversed-phase (RP) chromatography, through two coupling strategies: SEC x RP and RP x RP separations of the water-soluble polymers poly(methacrylic acid) (PMA) and polystyrene sulfonic acid (PSSA). Capillary-channeled polymer (C-CP) fiber (polyester and polypropylene) stationary phases were used for the RP separations. Particularly attractive is the fact that they are easily implemented as the second dimension in 2DLC workflows due to their low backpressure (<1000 psi at ∼70 mm sec−1) and fast separation times. In-line multi-angle light scattering (MALS) was also implemented for molecular weight determinations of the polymer samples, with the molecular weight of PMA ranging from 5 × 104 to 2 × 105 g mol−1, while PSSA ranges from 105 to 108 g mol−1. While the orthogonal pairing of SEC x RP addresses polymer sizing and chemistry, this approach is limited by long separation times (80 min), the need for high solute concentrations (PMA = 1.79 mg mL−1 and PSSA = 0.175 mg mL−1 to yield comparable absorbance responses) due to on-column dilution and subsequently limited resolution in the RP separation space. With RP x RP couplings, separation times were significantly reduced (40 min), with lower sample concentrations (0.595 mg mL−1 of PMA and 0.05 mg mL−1 of PSSA) required. The combined RP strategy provided better overall distinction in the chemical distribution of the polymers, yielding 7 distict species versus 3 for the SEC x RP coupling.

Achieving high heat-resistant property in dilute Mg-0.2Ce wrought alloy by retarding recrystallization process

Conventional heat-resistant Mg alloys always involve a high concentration of rare-earth solutes to produce amounts of thermostable second phases. In this work, however, the high heat resistance is achieved in a dilute Mg-0.2Ce (wt%) alloy, exhibiting a high ultimate tensile strength of ∼ 181 MPa at 250 ℃, which is superior to those of benchmark Mg alloys including ZK60, AZ80 and other rare-earth element containing Mg alloys. The high-temperature strength of present Mg alloy can be attributed to the suppressed recrystallization process due to the minor Ce addition, since the softening mechanism of grain boundary sliding at high-temperature can be effectively suppressed in the elongated un-recrystallized grains and the texture hardening is always effective in the deformed regions. In addition, the present Mg alloy exhibits excellent thermal stability during the long-term heating on account of the sluggish static recrystallized process. The high temperature strength decreases gradually with the annealing time, which can yet exceed 145 MPa after annealing at 300 ℃ for 6 h. Generally, the present work would provide important insight into developing novel low-alloyed and heat-resistant Mg wrought alloys.

Molecular Basis for Actin Polymerization Kinetics Modulated by Solution Crowding.

Actin polymerization drives cell movement and provides cells with structural integrity. Intracellular environments contain high concentrations of solutes, including organic compounds, macromolecules, and proteins. Macromolecular crowding has been shown to affect actin filament stability and bulk polymerization kinetics. However, the molecular mechanisms behind how crowding influences individual actin filament assembly are not well understood. In this study, we investigated how crowding modulates filament assembly kinetics using total internal reflection fluorescence (TIRF) microscopy imaging and pyrene fluorescence assays. The elongation rates of individual actin filaments analyzed from TIRF imaging depended on the type of crowding agent (polyethylene glycol, bovine serum albumin, and sucrose) as well as their concentrations. Further, we utilized all-atom molecular dynamics (MD) simulations to evaluate the effects of crowding molecules on the diffusion of actin monomers during filament assembly. Taken together, our data suggest that solution crowding can regulate actin assembly kinetics at the molecular level.