Nanobubbles Research Articles

Decrease in the Surface Tension of Nanobubble Dispersion in Water: Results of Surface Excess of Bulk Nanobubbles at Interfaces

The effect of nanobubbles (NBs) on the surface tension of liquid was investigated by three methods of different measuring principles, pendant drop (PD), Wilhelmy, and du Noüy methods, over a wide range of number concentration of bulk NBs (BNBs). In all of the three methods, the surface tension decreased in proportion to the number concentration of BNBs and the proportional constant was different among the three methods. Such behavior was inferred to be caused by the surface excess of BNBs at the gas-liquid or solid-liquid interface. In the PD method, the hydrophobic interaction between BNBs and air around a drop seems to cause the surface excess of BNBs along the surface of water drops. It brings about a subtle change in its profile, resulting in the decrease in surface tension, which takes a time of hundreds of seconds. Meanwhile, in the Wilhelmy and du Noüy methods, electrostatic attractive force between BNBs and a plate or ring is a likely cause of surface excess at the solid-liquid interface, resulting in the instantaneous decrease in surface tension. This study also provides a practical methodology of comparison for surface tension of NB dispersion: surface tension shall be compared among different samples with the same measurement method. Especially in the PD method, retention time of droplets before measurement shall be the same among samples.

Induksi Nanobubbles (NBs) untuk Pertumbuhan Anggrek Dendrobium Imelda Marina Masagung X Bumi Menangis

Nanobubbles (NBs), nanotechnology has been applied in several fields, such as health, waste management, agriculture, and others. This nanotechnology utilizes the gas in the bubbles, making it easier for the gas to enter the cell. This study aimed to determine the effect of O2, CO2, N2, H2, and O3 gases in NBs on the growth of the Dendrobium Imelda Marina Masagung ´ Bumi Menangis orchid. The method used was to provide fertilizer and NBs treatment to Dendrobium orchids for six weeks with observations every one week. The data obtained were analyzed by two-way ANOVA and further tested post hoc tests with Ptukey <0.05. The results showed significant differences in stem diameter and orchid plant height. The orchid stem diameter was more significant with the NBs treatment than the fertilizer and control treatments. Orchid plants with NBs treatment were higher than those with fertilizer and control treatments. The appearance of new shoots and roots also indicates plant growth. Orchid leaf colour with fertilizer and NBs treatment changed from the Yellow-Green Group (144) to the Green Group (143), except for the control. Leaves colour affects the process of photosynthesis, the green colour will carry out photosynthesis better than Green-Yellow leaves. This affects plant growth in Dendrobium Imelda Marina Masagung ´ Bumi Menangis orchid. NBs enlarge the stem, increase the height and make the leaves green.

Ballast water treatment by ozone nanobubbles

AbstractBACKGROUNDThe uncontrolled discharge of untreated ballast water, which is essential for a ship's optimal operation, is one of the major causes of sea environmental pollution by shipping. Among the disinfection methods available for ballast water treatment, ozonation is a commonly used method, but its performance is limited by the rapid ozone auto‐decomposition rate. Nanobubbles (NBs) technology has attracted much scientific interest as it is characterized by a long residence time in the aqueous phase and a high surface area; therefore, ozone nanobubbles (OzNBs) are expected to enhance disinfection capacity and residual activity. The present study was designed to provide further insight into the inactivation of heterotrophic bacteria in saline water and to examine the use of OzNBs for disinfection of saline water.RESULTSThe survival rate of Escherichia coli (E. coli), which was used as indicator microorganism, along with the ozone consumption at different salinities (1.5, 4, 8 and 15 PSU) and bacterial concentrations (107, 106, and 105 CFU mL−1) with and without supplementation of OzNBs were investigated. The results indicated a statistical difference in the residual concentration of total residual oxidants (TRO) with the presence of OzNBs at salinity level 1.5 PSU and at 4 PSU only at the lowest bacterial content. At a low salinity and high bacterial concentration, the concentration of TRO was 6‐fold higher in the presence of OzNBs.CONCLUSIONThe salinity of water has a strong impact on the residual concentration of ozone. When salinity is increased, ozone reacts more rapidly with the bromide and chloride ions. The use of OzNBs exhibited a greater disinfection performance and higher residual activity. © 2023 The Authors. Journal of Chemical Technology and Biotechnology published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry (SCI).

Nanobubbles: an emerging science in nanotechnology

Abstract Nanobubbles (NBs) are a practical, safe, innovative science widely used in many fields as advanced aeration technology. These have nano-size, hollow, spherical cavities enclosed gas pouches in an aqueous solution with shell and core structure. The core comprises active ingredients to deliver the drug to the target site. This approach is based on hydrodynamic cavitations and free radical generation on nano-sized bubble particles. The properties such as longevity, high internal pressure, large specific surface area in the nano range, virtual disappearance of buoyancy, and ability to dissolve gases namely oxygen, hydrogen, carbon dioxide, and ozone make it versatile and eco-friendly. These are negatively charged molecules and stabilize through zeta potential by its flotation property in the system. Different factors, including the effect of gases, temperature, pressure, pH, and concentration of surfactants, salt, and electrolytes, showed different kinds of impact on it. It is chosen to make our environment chemical-free over some harmful and hazardous chemicals that have an obnoxious odor and are unsafe for life. Recently, advanced, new technology-based NBs generators have been introduced to increase their efficiency and demand as per many industries’ requirements. This review focused on the history, properties, factors affecting, and methods of generation, measurements, applications, and future aspects of NBs in many biological, chemical, and pharmaceutical fields, among others. The global demand for the usage of NBs has increased by 5% worldwide. This emerging science showed great potential and would utilize in developing new-nano materials and concepts in nanotechnology.

Combination of ozone-based advanced oxidation process and nanobubbles generation toward textile wastewater recovery

The intricate nature of various textile manufacturing processes introduces colored dyes, surfactants, and toxic chemicals that have been harmful to ecosystems in recent years. Here, a combination ozone-based advanced oxidation process (AOP) is coupled with a nanobubbles generator for the generation of ozone nanobubbles (NB) utilized the same to treat the primary effluent acquired from textile wastewaters. Here we find several key parameters such as chemical oxygen demand ammonia content (NH3), and total suspended solids indicating a substantial recovery in which the respective percentages of 81.1%, 30.81%, and 41.98%, upon 300 min residence time are achieved. On the other hand, the pH is shifted from 7.93 to 7.46, indicating the generation of hydrogen peroxide (H2O2) due to the termination reaction and the self-reaction of reactive oxygen species (ROS). We propose that the reactive oxygen species can be identified from the negative zeta potential measurement (−22.43 ± 0.34 mV) collected in the final state of treatment. The combined method has successfully generated ozone nanobubbles with 99.94% of size distributed in 216.9 nm. This highlights that enhancement of ozone’s reactivity plays a crucial role in improving the water quality of textile wastewater towards being technologically efficient to date.

How to control the uniform micro bubbles generation on underwater superaerophobic surface?

Bubbles are an important medium to increase the efficiency of gas/liquid mass transfer. Smaller and more homogeneous bubbles can improve environmental treatment efficiency, microfluidic stability, and medical imaging capabilities. At present, it is still difficult to produce uniform micro bubbles and stably apply them into complex environment. Herein, a strategy of aerating micro bubbles by designing four different structures via laser ablation is proposed. The underwater superaerophobic polyimide (SPI) with micro volcano-like channels has been verified to produce bubbles with a volume of nanoliter. It is attributed to the combination of the micro-nano rough structures covering the surface and the micro-volcanic structure limiting the expansion of bubbles. The SPI with micro volcano-like structure, as a porous aeration film, can make various gases pass, which can be applied to water purification and gas detection. It is also found that the designed SPI with micro volcano-like structure can resist the damage of complex application environments, such as extreme water environments and ultraviolet radiation. As indicated in all the results, the SPI is applicable and flexible. The femtosecond laser can realize high precision and good controllability of the superaerophobic surface, which is difficult for other traditional methods to fabricate micropores. This distinctive membrane provides a new inspiration to design advanced materials for applications in gas transport and collection, wastewater treatment, and chemical reactions. It is also helpful to promote the basic research and applications of micro and nano bubbles generation.

Degradation of Rhodamine B in the photocatalytic reactor containing TiO2 nanotube arrays coupled with nanobubbles

Although photocatalytic technology is applied in water treatment, the challenge still exists due to its low photocatalytic performance. Herein, a photocatalytic reactor coupled with nanobubbles (NBs) is developed to degrade organic pollutants in wastewater. The reactor contains Ti mesh coated with TiO2 nanotube arrays as a photocatalyst. The introduction of NBs in the reactor increases the dissolved oxygen content to enhance photocatalytic performance. The photocatalytic reactor exhibits outstanding photocatalytic performance, and the degradation ability of Rhodamine B is 95.39% after 2 h of irradiation treatment. The reactor also shows excellent photodegradation performance for other organic pollutants, such as methylene blue (74.23%), tetracycline (68.68%), and oxytetracycline hydrochloride (64.10%). Radical trapping experiments further prove that ·O2−, h+ and ·OH are the active species for the degradation of RhB in the photocatalytic system. Therefore, this work provides a feasible strategy to design a photocatalytic reactor coupling with nanobubbles technology for the photodegradation of organic pollutants in wastewater.

Experimental Investigation of Cavitation Bulk Nanobubbles Characteristics: Effects of pH and Surface-Active Agents

Nanobubbles (NBs) have a widespread application in antimicrobial activity, wastewater treatment, and ecological restoration due to numerous peculiar characteristics, such as small diameter, long-term stability, and ability to produce hydroxyl radicals. Despite significant applications, only limited comprehensive investigations are available on the role of surfactants and pH in NBs characteristics. Therefore, this study examines the effects of different surfactants (i.e., anionic, cationic, and nonionic) and pH medium on bulk NB formation, diameter, concentration, bubble size distribution (BSD), ζ-potential, and stability. The effect of surfactant at concentrations above and below the critical micelle concentration was investigated. NBs were generated in deionized (DI) water using a piezoelectric transducer. The stability of NBs was assessed by tracking the variation in diameter and concentration over time. In a neutral medium, the diameter of NBs is smaller than in other surfactant or pH mediums. The diameter, concentration, BSD, and stability of NBs are strongly influenced by the ζ-potential rather than the solution medium. BSD curve shifts to a smaller bubble diameter when the magnitude of ζ-potential is high in any solution. In pure water, surfactant, and pH mediums, NBs have existed for a long time. NBs have a shorter life span in environments with a pH ≤ 3. Surfactant adsorption on the surface of NBs increases with increasing surfactant concentration up to a certain limit, beyond which it declines substantially. The Derjaguin-Landau-Verwey-Overbeek (DLVO) theory was used to interpret the NBs stability, resulting in a total potential energy barrier that is positive and greater than 45.55 kBT for 6 ≤ pH ≤ 11, whereas for pH < 6, the potential energy barrier essentially vanishes. Moreover, an effort has also been made to explicate the plausible prospect of ion distribution and its alignment surrounding NBs in cationic and anionic surfactants. This study will extend the in-depth investigation of NBs for industrial applications involving NBs.

Oxygen-Rich Graphene/ZnO2-Ag nanoframeworks with pH-Switchable Catalase/Peroxidase activity as O2 Nanobubble-Self generator for bacterial inactivation

The oxygen-rich organic/inorganic (reduced graphene oxide (rGO)/ZnO2-Ag) nanoframeworks as suppliers of O2 nanobubbles (NBs) with dual pH-and-temperature-sensitive behavior were developed to suppress bacterial growth. It was demonstrated that not only the rate but also the final product of oxygen-rich ZnO2 decomposition (to an intermediate product of H2O2) rate was dramatically controlled by pH adjustment. Furthermore, in the presence of Ag nanoparticles, ̇OH radical generation switched to O2 NBs evolution by shifting the pH from acidic to basic/neutral conditions, demonstrating an adjustable nanozyme function-ability between catalase and peroxidase-like activity, respectively. Antibacterial properties of the in-situ generated O2 NBs substantially enhanced against bacterial models including methicillin-resistant Staphylococcus aureus in the presence of rGO. In fact, deflecting the electrons from their main respiratory chain to an oxygen-rich bypath through rGO significantly stimulated reactive oxygen species (ROS) generation, combating bacteria more efficiently. Moreover, NIR laser irradiation-induced temperature rise (due to the inherent photothermal properties of rGO) facilitated ZnO2 decomposition and accelerated growth and collapse of NBs. The simultaneous microscale thermal and mechanical destructions induced stronger antibacterial behavior. These results hold great promises for designing simple organic/inorganic nanoframeworks as solid sources of NBs with tunable enzyme-like ability in response to environmental conditions suitable for forthcoming graphene-based bio-applications.

Solubilization and remediation of polycyclic aromatic hydrocarbons in groundwater by cationic surfactants coupled nanobubbles: Synergistic mechanism and application

Polycyclic aromatic hydrocarbons pose a severe threat to groundwater and the soil environment. Improving the efficiency of the surfactant-enhanced remediation (SER) technique is a research hotspot. Nanobubbles (NBs) were introduced to enhance the solubilization effect of cationic surfactant dodecyltrimethylammonium bromide (DTAB) on phenanthrene (PHE). The interaction between NBs and DTAB was favorable in reducing the critical micelle concentration of DTAB. The equilibrium solubilization of DTAB to PHE was upgraded by up to 30.4% with the synergy of NBs. The effect of DTAB concentration on the stability of NBs was an essential reason for the different upgrade rates. The kinetic study showed that the process of equilibrium solubilization was accelerated, while NBs were “consumed”. Based on the classic DLVO framework, OH– and inorganic ions in groundwater can participate in the formation of micelles and change the double electric layer thickness of bubbles, which are the key factors affecting the stability of NBs. The results revealed the colloidal interface characteristics and the particle behavior of micelles with NBs, providing new insight into the combined application of micelles or vesicles with NBs.

Mechanisms of synergistic inhibition of NaCl and glycine mixtures on methane hydrate formation: Experimental and molecular dynamic simulation

Composite inhibitors exhibit significant performance in inhibiting hydrate nucleation and growth and reducing hydrate production, however, their working processes and mechanisms need to be further clarified. Herein, the effects of NaCl-glycine mixture on methane hydrate formation and the underlying mechanisms were investigated through experimental and molecular dynamic simulation. The results showed that in addition to changing the phase equilibrium conditions of the hydrate, NaCl can inhibit hydrate growth owing to the salt resistance of water clathrate structures. Glycine, which is a promising new inhibitor, possesses both kinetic and thermodynamic inhibition capabilities. The ratio C of water molecules disturbed by the mixture of NaCl and glycine decreased to below 0.733, and the hydrate phase equilibrium pressure increased to above 3.919 MPa, which effectively inhibited hydrate nucleation and growth. Moreover, during the hydrate growth stage, NaCl reduced the solubility of methane and glycine promotes the formation of methane nano bubbles, associated with the accelerated diffusion and high degrees of disorder of water molecules in the composite inhibitor solution, which further hindered hydrate growth. A higher glycine dosage led to stronger synergistic inhibition. When the mixture consists of 5.0 wt% glycine and 3.5 wt% NaCl, the induction time was 10.69 times longer than that of pure water, and correspondingly, the methane consumption decreased by 51.35%, with the average methane consumption rate dropping by 75.38%.

Exploring the Role of Nanobubbles in the Fate and Transport of Spilled Oil on Shorelines

Nanobubbles (NBs) generated by wave breaking and shearing are abundant and stable in the ocean. However, few studies have focused on the effects of NBs in the fate and transport of pollutants in the shoreline environment. In this study, the properties of NBs were determined, as well as the influencing factors. The role of NBs in the fate and transport of spilled oil were further investigated. The results showed that NBs significantly increased the concentration of dissolved oxygen as well as changed the pH, zeta potential, and surface tension of the water. Low salinity favored the generation of NBs, while high salinity inhibited this process. The surface active materials played a positive role in the generation and stabilization of NBs. With the assistance of external energy, the bulk NBs enhanced the efficiency in oil detachment from the surface of the substrate. At the same time, the surface NBs on the substrate obstructed the downward transport of oil colloids. Considering the behavior between the NBs in two different phases and the oil droplets, the oil droplets tended to bind to the NBs. This study demonstrates that NBs can play a significant role in the environmental behaviors of pollutants in the coastal areas.

Adhesion between nanobubbles and fine cassiterite particles

Adhesion is an important process of particle-bubble interaction in fine particle (−10 μm) flotation. This paper studied the adhesion process and mechanism between nanobubbles and fine cassiterite particles by using a high-speed camera, atomic force microscope (AFM), adsorption capacity tests, and induction time tests. After being pretreated with nanobubbles (NBs) water, fine cassiterite particles flotation tests were carried out using caprylhydroxamic acid (CHA) as a collector. The results showed that NBs can improve the recovery and flotation rate of fine cassiterite while decreasing the collector dosage. The adsorption capacity test indicated that the cassiterite treated with NBs had lower demand for collector concentration. The AFM imaging results further demonstrate that NBs could reduce the adsorption of CHA on the surface of minerals. Since NBs played a part of the role of collector, it can improve the flotation effect while reducing the amount of collector. The induction time test and the high-speed camera observation test showed that NBs promoted the attachment between bubbles and cassiterite particles. On the other hand, NBs agglomerate cassiterite particles, increasing the probability of particles colliding with bubbles.

Molecular Approach for Understanding the Stability, Collision, and Coalescence of Bulk Nanobubbles

Though long-lived nanobubbles (NBs) have been reported by multiple researchers, the underlying reason behind their stability is still obscure. Some of the conjectured reasons include diffusive shielding, the presence of surface charges, and stability due to contamination. Still, the stability of NBs against coalescence and Ostwald ripening is not confirmed. Using molecular dynamics simulations, the present study aims to understand the stabilization effects due to diffusive shielding and the presence of an electrical double layer at the surface of NBs. Accumulation of charges on NBs for different concentrations of ions is discussed. Also, the collision of equal-sized NBs with different approach velocities and offset distances is simulated. A regime map is predicted on the basis of initial approach velocity and offset distance. The transition in regime obtained upon increasing the offset distance is discussed, which differs from the collision characteristics of macroscopic bubbles and drops. The merging of NBs is initiated through the bridge formation, for which the temporal evolution rate along with the scaling argument is presented. The stress terms involved and the corresponding regimes are predicted based on the fluid properties. For all the cases where merging is observed, the estimated probability is observed to be low, which suggests the stability of NBs against coalescence.

Stability of soluble bulk nanobubbles: Many-body dissipative particle dynamics analysis

Bulk nanobubbles (bNBs) have attracted considerable research attention due to their broad application prospects. Numerous experiments have demonstrated the stability of nanobubbles (NBs) in solution, but further investigation is needed to determine their stability mechanism. This paper investigates the properties of bNBs using mesoscopic simulations based on many-body dissipative particle dynamics (MDPD). Based on the standard insoluble bubble model, the soluble bubble model is developed by modifying the attraction amplitude between gas and liquid. This modification determined the range of soluble bubble parameters. The new surface tension calculation model indicates that reducing the surface tension is helpful to the stability of soluble bubbles. In contrast, surface tension changes do not affect the stability of insoluble bubbles. The two bubble models follow the Young-Laplace equation to analyze further the internal density, pressure, gas diffusion, and other characteristics of bNBs. The results show that the gas in bNBs has a high density and pressure. In addition, as the size of the bNBs decreases, the gas density and pressure in the bNBs also increase. In the soluble bubble, the gas density is not uniform, and the gas in the soluble bubble forms a density peak at the gas-liquid interface. The density peak in the bNBs delays the outward diffusion of the gas to maintain its stability. This study aims to provide a method to simulate bNBs, reveal their characteristics, and explore the influence of non-uniform density in bNBs on diffusion.

The Influence of Nanobubble Size and Stability on Ultrasound Enhanced Drug Delivery.

Lipid-shelled nanobubbles (NBs) are emerging as potential dual diagnostic and therapeutic agents. Similar to their micron-scale counterparts, microbubbles (1-10 μm), they can act as ultrasound contrast agents as well as locally enhance therapeutic uptake. Recently, it has been shown that the reduced size of NBs (<1 μm) promotes increased uptake and accumulation in tumor interstitial space, which can enhance their diagnostic and therapeutic performance. However, accurate characterization of NB size and concentration is challenging and may limit their translation into clinical use. Their submicron nature limits accuracy of conventional microscopy techniques, while common light scattering techniques fail to distinguish between subpopulations present in NB samples (i.e., bubbles and liposomes). Due to the difficulty in the characterization of NBs, relatively little is known about the influence of size on their therapeutic performance. In this study, we describe a novel method of using a commercially available nanoparticle tracking analysis system, to distinguish between NBs and liposomes based on their differing optical properties. We used this technique to characterize three NB populations of varying size, isolated via centrifugation, and subsequently used this to assess their potential for enhancing localized delivery. Confocal fluorescence microscopy and image analysis were used to quantify the ultrasound enhanced uptake of fluorescent dextran into live colorectal cancer cells. Our results showed that the amount of localized uptake did not follow the expected trends, in which larger NB populations out-perform smaller NBs, at matched concentration. To understand this observed behavior, the stability of each NB population was assessed. It was found that dilution of the NB samples from their stock concentration influences their stability, and it is hypothesized that both the total free lipid and interbubble distance play a role in NB lifetime, in agreement with previously proposed theories and models.

The generation and stability of bulk nanobubbles by compression-decompression method: The role of dissolved gas

Nanoscale gas bubbles are paid more and more attention due to their significant applications in different fields including the environmental remediation, plant and animal growth as well as medical diagnosis, etc. As reported, the local gas saturation plays an important role for the formation of surface nanobubbles (NBs) but is less importance for their stability. As for bulk NBs, few researches focused on the influence of dissolved gas on their generation and stability because it is thought generally that a limited amount of gas could dissolve into water. Herein, we reported for the first time the relationship of dissolved gases (Kr, O2 and N2) and the formation and stability of bulk NBs. Firstly, we developed a compression-decompression method to produce the water with super-high concentration of dissolved gas. About 60 mg/L oxygen dissolved gas was created to promote the formation of bulk NBs. It was showed that high bulk NB concentrations were produced using the compression-decompression method by controlling the loading pressure and time at the same time. The evolution process showed that the concentration of dissolved gas would decrease quickly with the deposited time. However, the concentration of formed bulk NBs did not follow the same way as dissolved gas concentration. It exhibited a complicated change over the time. Typically, first sharp increase to one order higher concentration than at the beginning and then decreased with a fluctuation within 72 h. More interestingly, the time of this sharp increase in nanobubble concentration depended on the type of gas, the krypton (Kr) gas system took longer time to reach the highest concentration and the oxygen (O2) as well as nitrogen (N2) gas system reached the highest concentration at about 4 h generally. The change of zeta potential of those NBs followed the same fluctuation as their concentration. Finally, we presumed a theoretical model to explain the evolution mechanism of bulk NBs. It indicated that there is a competition of different bubble behaviors (nucleation, clustering and coalescence) in different time periods. This study provides a new technique to produce high concentration of bulk NBs and dissolved gas in solution. Those results are very significance for further understanding the mechanism of formation and stability of bulk NBs under a super-high concentration of dissolved gas and may be used in some chemical reactions related with gas to promote the reaction efficiency.

Nanobubbles containing PD-L1 Ab and miR-424 mediated PD-L1 blockade, and its expression inhibition to enable and potentiate hepatocellular carcinoma immunotherapy in mice

Immune checkpoint inhibitors (ICI) therapy is the main type of immunotherapy for cancer. Current clinical trials are focused on enhancing anti-tumor effects through combinations of multiple ICIs with agents that cause tumor cell death and release tumor antigens. In this study, weprepared nanobubbles (NBs) to load programmed death-ligand 1 (PD-L1) antibody andmiR-424gene to evaluate the combined anti-tumor activity of the targeted NBs.The miR-424 gene was chosen to be an anti-tumor gene, which can target PD-L1 and Bcl-2, through bioinformatics analysis and target gene verification. Then, PD-L1 Ab/miR-424-NBs were prepared by thin-film hydration. The optimal shape, size, and character of the NBs were determined by scanning electron microscopy and Zeta potential study. In addition, the antibody binding rate and gene loading of the targeted NBs were studied by agarose gel electrophoresis and flow cytometry, respectively. The synergistic immunotherapeutic effect of anti-PD-L1 antibody andmiR-424in vivo and their mechanism were evaluated using an H22 hepatoma transplanted tumor model in mice,whichproved that the targeted NBs mediated the PD-L1 antibody toblock the PD-1/PD-L1 signaling pathway and the transfected miR-424gene to downregulate the PD-L1 expression of tumor cells, both of which enhanced the antitumor immune effect mediated by T cells. It was also found that the targeted NBs activated T cells, which released a large number of cytokines, such as IFN-γ and IL-2, to recruit and activate macrophages and NK cells. It is suggested that ultrasound-mediated PD-L1 antibody NBs delivering miR-424 can inhibit the growth of subcutaneously transplanted hepatocellular carcinoma in terms of apoptosis and immunity. Therefore, ultrasound-mediated targeted NBs are a potential effective carrier for liver cancer, and PD-L1 antibody and miR-424 have a synergistic anti-tumor immunotherapy effect.

Nanobubble-mediated co-delivery of Ce6 and miR-195 for synergized sonodynamic and checkpoint blockade combination therapy with elicitation of robust immune response in hepatocellular carcinoma

MicroRNAs (miRNAs) is the tiny and highly conserved noncoding RNAs, regulate gene expression at the post-transcriptional level by binding to the 3′-UTR of target mRNAs. Several studies found that miR-195 plays an unavoidable role in the regulation of cell proliferation, cycle and apoptosis in hepatocellular carcinoma (HCC). Here, we constructed miR-195 and Chlorine e6 (Ce6) co-loading NBs (nanobubbles), making use of NBs as carriers to deliver miR-195 and Ce6 to mouse tumor models. Our results showed that the binding between PD-1 and PD-L1 was blocked by upregulating miR-195 expression. The analysis of CTL (Cytotoxic T Cell) immune activity in the treatment group was higher than the control group. Simultaneously, Ce6 was used as sonosensitizer to induce SDT (sonodynamic therapy) and trigger ICD (immunogenic cell death) of tumor cell via generation of ROS. Recent studies have found that ICD may further enhance anti-tumor immunity against PD-L1. Results indicated that combination treatment effectively stimulated infiltration of T cell and the activation of natural killer (NK) cells as well as the maturation of dendritic cells (DCs), and the combination treatment group exibited the highest CTL killing activity. These results indicate that a stronger antitumor immunity was triggered via combination of SDT-induced tumor cell ICD and immune checkpoint blockade of PD-1/PD-L1 mediated by upregulation of miR-195. In conclusion, we have successfully constructed an efficient delivery system with great potential to provide a new strategy for synergistic immunotherapy.

Improvement of fine muscovite flotation through nanobubble pretreatment and its mechanism

With the increasing demand for mineral resources, it is necessary to further recycle some fine muscovite which are not of high quality and discarded after the first development. This study was to improve the recovery of fine muscovite (−20 μm) by introducing of nanobubbles (NBs). A series of techniques including flotation test, mineral adsorption capacity measurement, Zeta potential measurement and the visualization of mineral and bubble interaction were used to investigate the flotation effect of NBs pretreatment on fine muscovite. The results showed that in the dodecylamine (DDA) flotation system, the flotation recovery of fine muscovite pretreated by NBs was higher than that without NBs pretreatment under any concentration of collector and flotation recovery was increased by about 7 %. Meanwhile, the dosage of reagent was reduced by 25 % at the same recovery. NBs pretreatment could reduce the adsorption capacity of DDA and electrostatic repulsion of the muscovite particles, which was beneficial to form particle agglomeration. In addition, the three-phase contact line of the muscovite pretreated with NBs could be formed faster (34 ms). Furthermore, the trajectory of muscovite particles pretreated by NBs were closer to bubbles, and easier to form obvious agglomeration. The introduction of NBs can enhance the flotation of fine muscovite, which provide a cost-effective approach for the fine particle flotation.