Search Results (25)

Background: Vascular imaging is essential for clinical practice, research, and the diagnosis and management of vascular diseases. Super-resolution ultrasound (SRUS) imaging is an emerging high-resolution imaging technique with broad applications in soft tissue vascular imaging. However, the impact of biological and clinical variables on its imaging accuracy is currently unknown. This study investigates these factors in an animal model and compares SRUS with contrast-enhanced µCT. Methods: Kidney scans from 29 Zucker rats (Zucker Diabetic Fatty and Zucker Lean) were retrospectively analysed. The left kidney was imaged in vivo using SRUS during microbubble infusion, then filled with Microfil and excised for ex vivo µCT. SRUS parameters and clinical variables were analysed, and SRUS scans were co-registered with µCT to compare vascular density measurements. Results: Mean arterial blood pressure and anaesthesia time showed significant linear relationships with SRUS microbubble detection and vascular track reconstruction. The anaesthesia time was also strongly correlated with vascular density measurement. Visualisation and velocity estimations of renal arteries were limited with SRUS. Ultrasound signal attenuation had significant impacts, particularly in cortical far-field imaging. Despite differences between kidney regions, the vascular density distribution did not differ considerably between SRUS and µCT datasets for whole-kidney imaging. Conclusions: This study outlines key factors SRUS users must consider for optimal technique use. Careful region selection and control of clinical variables ensure more reliable and comparable images. Further research is necessary to translate these findings from a rat model into clinical application. Full article

Towards the bioremediation of toxic compounds from aquatic environments using living microalgae, Chlorella vulgaris has emerged as a promising candidate for the removal of heavy metals. The present study advances the scale-up of the microalga’s culture and investigates its efficiency in multi-metal removal (Cu, Cd, Ni, Pb, and Zn at 1 ppm each). Two aeration conditions were investigated: standard/conventional aeration (SA), and an innovative, custom-built micro-bubble aeration (MBA), which optimizes CO₂ residence time to enhance photosynthesis. Conducted in a pilot-scale 30 L photobioreactor (PBR) over a cultivation period of 7 days, control and multi-metal treated cultures were monitored for pH, cell population growth, and pigment content. Heavy metal removal efficiency was evaluated by means of atomic absorption spectroscopy (AAS) on Days 3 and 7 of cultivation. The comparative results reveal that MBA significantly enhances both the population and the photosynthetic pigment content of the cultures. Furthermore, the heavy metal removal efficiency under MBA reached up to 95% even by Day 3 of cultivation, remarkably higher than the 67% of the SA treated culture. These findings not only demonstrate Chlorella vulgaris’s effectiveness in multi-metal treated systems but also highlight the potential of advanced aeration systems to enhance bioremediation efficiency in larger-scale aquatic environments. Full article

Oncolytic virotherapy has shown great promise in mediating targeted tumor destruction through tumor-selective replication and induction of anti-tumor immunity; however, obstacles remain for virus candidates to reach the clinic. These include avoiding neutralizing antibodies, preventing stimulation of the adaptive immune response during intravenous administration, and inducing sufficient apoptosis and immune activation so that the body’s defense can work to eradicate systemic disease. We have developed a co-formulation of oncolytic viruses (OVs) with Imagent^® lipid-encapsulated, perfluorocarbon microbubbles (MBs) to protect the OVs from the innate and adaptive immune system. Once inside the MB, the viral particles become acoustically active such that external ultrasound can target the delivery of the virus locally within the tumor. Humanized NSG female mice (Hu-CD34⁺ NSG-SGM3) engrafted in their flanks with MDA-MB-231-Luc triple-negative breast cancer (TNBC) cells were transduced with MB/OVs, with or without adjuvant Pembrolizumab treatment, and tumor sizes and tumor necrosis were assessed. The presence of CD8⁺ (cytotoxic T-cells), CD4⁺ (helper T-cells), and CD25⁺ (Tregs) tumor-infiltrating lymphocytes (TILs) was quantified in the tumor samples by immunohistochemistry. In an in vivo model of humanized mice engrafted with a human immune system, we observed significantly greater tumor necrosis and smaller tumor mass in human TNBC xenografts systemically treated with MB/OV complexes in the presence or absence of pembrolizumab adjuvant treatment, compared to controls. Additionally, we observed a low ratio of CD4⁺/CD8⁺ TILs and a high ratio of CD8⁺/CD25⁺ TILs in the MDA-MB-231 xenografts treated with MB/OVs complexes with or without pembrolizumab adjuvant treatment, compared to controls. Our study demonstrated the feasibility of using MBs to target OVs to TNBC through diagnostic ultrasound, which decreased tumor mass by increasing tumor necrosis and stimulated a local and systemic antitumoral immune response by increasing intratumoral CD8⁺ T-cytotoxic lymphocyte infiltration and decreasing CD25⁺ Treg cells. Full article

This work reports a simple bubble generator for the high-speed generation of microbubbles with constant cumulative production. To achieve this, a gas–liquid co-flowing microfluidic device with a tiny capillary orifice as small as 5 μm is fabricated to produce monodisperse microbubbles. The diameter of the microbubbles can be adjusted precisely by tuning the input gas pressure and flow rate of the continuous liquid phase. The co-flowing structure ensures the uniformity of the generated microbubbles, and the surfactant in the liquid phase prevents coalescence of the collected microbubbles. The diameter coefficient of variation (CV) of the generated microbubbles can reach a minimum of 1.3%. Additionally, the relationship between microbubble diameter and the gas channel orifice is studied using the low Capillary number (Ca) and Weber number (We) of the liquid phase. Moreover, by maintaining a consistent gas input pressure, the CV of the cumulative microbubble volume can reach 3.6% regardless of the flow rate of the liquid phase. This method not only facilitates the generation of microbubbles with morphologic stability under variable flow conditions, but also ensures that the cumulative microbubble production over a certain period of time remains constant, which is important for the volume-dominated application of chromatographic analysis and the component analysis of natural gas. Full article

Ultrasound contrast agents are clinically used for diagnosis of internal organs, but ultrasound contrast agents are rarely applied clinically in musculoskeletal disorders. Our study aims to comparatively analyze the differences between ultrasonographic images through peri-injury injection of the clinically used microbubble and researched nanoparticle contrast agents in various muscular injury models. To compare contrast-enhanced images in different muscle injury models, we prepared groups of rats with sham, laceration, punch, contusion, and toxin injection injuries. We measured H₂O₂ levels using the Amplex Red assay by extracting tissue from the damaged area. As comparative contrast agents, SonoVue^®, a commercially available microbubble contrast agent, and poly(vanillinoxalte) (PVO) nanoparticles, which are H₂O₂-responsive nanoparticles, were used. The difference in contrast between the two contrast agents was recorded as an ultrasound movie, and J-image software 1.53p was used to quantify and analyze the maximum and minimum echogenicity values of the images after contrast enhancement. In the Amplex red assay for the highest H₂O₂ level in each muscle injury model, the maximum level showed 24 h after the modeling. In the sham rats, PVO injection showed no increased echogenicity except at the needle insertion site, but SonoVue^® injection showed increased echo signal throughout the injected muscle immediately after injection. One day after the preparation of the lesion, PVO and SonoVue^® were injected into the lesion site and ultrasound was performed on the lesion site. After the injection of PVO nanoparticles, contrast enhancement was observed at the lesion site immediately. SonoVue^® injections, on the other hand, showed a widespread pattern of echo signals and an increase in echo retention only at the lesion site over time, but this was not clear. There were statistically significant differences between the highest and lowest echogenicity in PVO and SonoVue^® contrast-enhanced images in all models. Contrast enhancement lasted more than 3 h in the PVO injection, but disappeared within 3 h in the SonoVue^® injection. PVO nanoparticles showed the possibility of physiologic contrast by CO₂ generated by conjugation with H₂O₂ generated by muscle injuries, and SonoVue^® injection observed the possibility of microbubble contrast as a contrast agent with a pooling effect that lasts longer on the lesion. Further research is needed to investigate the use of various ultrasound contrast agents, including nanoparticles, in musculoskeletal disorders, as well as the potential for further utilities of microbubble contrast agents. Full article

The froth flotation technique can be considered one of the most efficient methods for the separation of minerals. Prior to utilizing any physicochemical separation method, the size of the mined ore must be decreased to facilitate the release of the valuable materials. This practice, along with the increased exploitation of ores that carry fine mineral particles caused the production of fine and ultrafine particles which are difficult to recover with classical enrichment methods, due to their different characteristics compared to coarser particles. It is established that fine and ultrafine particles are difficult to float, leading to losses of valuable minerals, mainly due to their low collision efficiency with bubbles. Moreover, fine particles require higher reagent consumption due to the fact that have a higher specific area, and finally, their flotation is limited by low kinetic energy. Flotation of fines can be enhanced by either decreasing bubble diameter or increasing their apparent size, or moreover, by enhancing the collector’s adsorption (their hydrophobic behavior) using alternative reagents (non-ionic co-collectors). In the present research, flotation experiments on a hybrid electrolytic flotation column that can produce microbubbles (−50 μm), were carried out for recovering fine magnesite (−25 μm) particles. In addition, the synergistic effect of anionic/non-ionic collectors were studied for the enhancement of fines recovery. Experimental flotation results so far designate the enhancement of fine magnesite particle recovery by approximately 8% with the addition of microbubbles. Finally, the synergistic effect of anionic/non-anionic collectors led to the improvement of flotation recovery by almost 12%. Full article

Livestock digestate provides nutrients and organic matter to the soil while increasing agricultural sustainability. Nevertheless, nitrogen (N) losses due to the nutrient surplus in regions characterized by intensive animal farming activities still represent an unsolved issue. For this purpose, digestate needs proper treatment and management to avoid N losses in the environment. In the livestock farming context, anaerobic digestion (AD) can be accompanied by an ammonia stripping (AS) process for N recovery. This paper aims to investigate the feasibility AS prior to and after AD of the manure, focusing on two different livestock farms, representative of dairy cattle and pig breeding in southern Italy. AS was performed at a lab scale by injecting microbubbles of air, which allowed the pH to increase, and thus the removal of ammonia. The results show that treating a dairy raw slurry with high intermediate alkalinity (IA) (6707 mg CaCO₃ L⁻¹) with AS may not be convenient in terms of total ammonia nitrogen (TAN) reduction. As a matter of fact, the loss of buffering capacity during the stripping process resulted in a pH never exceeding the value of 9, which could not promote free ammonia volatilization, whereas integrating AD with AS allowed us to obtain a 34% higher TAN reduction under the same stripping conditions at a temperature (T) of 38 °C and a gas-to-liquid ratio (G/L) of 1:1. Therefore, the AS removal efficiency strongly depends on the characteristics (mainly IA) of the treated matrix. High IA values suggest a possible high concentration of volatile fatty acids, which hinders pH increases and, thus, enables ammonia stripping. Despite the initial matrix origin, a low IA compared to the total alkalinity (TA) (<20% of TA) ensures a greater ammonia removal efficiency, which could be similar between digestate and raw manure in the same operative process conditions. Nonetheless, the amount of ammonia stripped is related to the initial TAN concentration of the specific matrix. Full article

The main aim of this study is to synthesize contrast microbubbles (MB) functionalized with engineered protein ligands using a microfluidic device to target breast cancer specific vascular B7-H3 receptor in vivo for diagnostic ultrasound imaging. We used a high-affinity affibody (ABY) selected against human/mouse B7-H3 receptor for engineering targeted MBs (TMBs). We introduced a C-terminal cysteine residue to this ABY ligand for facilitating site-specific conjugation to DSPE-PEG-2K-maleimide (M. Wt = 2.9416 kDa) phospholipid for MB formulation. We optimized the reaction conditions of bioconjugations and applied it for microfluidic based synthesis of TMBs using DSPE-PEG-ABY and DPPC liposomes (5:95 mole %). The binding affinity of TMBs to B7-H3 (MB_B7-H3) was tested in vitro in MS1 endothelial cells expressing human B7-H3 (MS1_B7-H3) by flow chamber assay, and by ex vivo in the mammary tumors of a transgenic mouse model (FVB/N-Tg (MMTV-PyMT)634Mul/J), expressing murine B7-H3 in the vascular endothelial cells by immunostaining analyses. We successfully optimized the conditions needed for generating TMBs using a microfluidic system. The synthesized MBs showed higher affinity to MS1 cells engineered to express higher level of hB7-H3, and in the endothelial cells of mouse tumor tissue upon injecting TMBs in a live animal. The average number (mean ± SD) of MB_B7-H3 binding to MS1_B7-H3 cells was estimated to be 354.4 ± 52.3 per field of view (FOV) compared to wild-type control cells (MS1_WT; 36.2 ± 7.5/FOV). The non-targeted MBs did not show any selective binding affinity to both the cells (37.7 ± 7.8/FOV for MS1_B7-H3 and 28.3 ± 6.7/FOV for MS1_WT cells). The fluorescently labeled MB_B7-H3 upon systemic injection in vivo co-localized to tumor vessels, expressing B7-H3 receptor, as validated by ex vivo immunofluorescence analyses. We have successfully synthesized a novel MB_B7-H3 via microfluidic device, which allows us to produce on demand TMBs for clinical applications. This clinically translatable MB_B7-H3 showed significant binding affinity to vascular endothelial cells expressing B7-H3 both in vitro and in vivo, which shows its potential for clinical translation as a molecular ultrasound contrast agent for human applications. Full article

Carbon capture utilization and storage (CCUS) technologies are regarded as an economically feasible way to minimize greenhouse gas emissions. In this paper, various aspects of CCUS are reviewed and discussed, including the use of geological sequestration, ocean sequestration and various mineral carbon mineralization with its accelerated carbonization methods. By chemically reacting CO₂ with calcium or magnesium-containing minerals, mineral carbonation technology creates stable carbonate compounds that do not require ongoing liability or monitoring. In addition, using industrial waste residues as a source of carbonate minerals appears as an option because they are less expensive and easily accessible close to CO₂ emitters and have higher reactivity than natural minerals. Among those geological formations for CO₂ storage, carbon microbubbles sequestration provides the economic leak-free option of carbon capture and storage. This paper first presents the advantages and disadvantages of various ways of storing carbon dioxide; then, it proposes a new method of injecting carbon dioxide and industrial waste into underground cavities. Full article

Recent developments in ultrafine bubble generation have opened up new possibilities for applications in various fields. Herein, we investigated how substances in water affect the size distribution and stability of microbubbles generated by a common nanobubble generator. By combining light scattering techniques with optical microscopy and high-speed imaging, we were able to track the evolution of microbubbles over time during and after bubble generation. Our results showed that air injection generated a higher number of microbubbles (<10 $\mathsf{\mu }$m) than CO₂ injection. Increasing detergent concentration led to a rapid increase in the number of microbubbles generated by both air and CO₂ injection and the intensity signal detected by dynamic light scattering (DLS) slightly increased. This suggested that surface-active molecules may inhibit the growth and coalescence of bubbles. In contrast, we found that salts (NaCl and Na₂CO₃) in water did not significantly affect the number or size distribution of bubbles. Interestingly, the presence of oil in water increased the intensity signal and we observed that the bubbles were coated with an oil layer. This may contribute to the stability of bubbles. Overall, our study sheds light on the effects of common impurities on bubble generation and provides insights for analyzing dispersed bubbles in bulk. Full article

Tumor hypoxia (oxygen deficiency) is a major contributor to radiotherapy resistance. Ultrasound-sensitive microbubbles containing oxygen have been explored as a mechanism for overcoming tumor hypoxia locally prior to radiotherapy. Previously, our group demonstrated the ability to encapsulate and deliver a pharmacological inhibitor of tumor mitochondrial respiration (lonidamine (LND)), which resulted in ultrasound-sensitive microbubbles loaded with O₂ and LND providing prolonged oxygenation relative to oxygenated microbubbles alone. This follow-up study aimed to evaluate the therapeutic response to radiation following the administration of oxygen microbubbles combined with tumor mitochondrial respiration inhibitors in a head and neck squamous cell carcinoma (HNSCC) tumor model. The influences of different radiation dose rates and treatment combinations were also explored. The results demonstrated that the co-delivery of O₂ and LND successfully sensitized HNSCC tumors to radiation, and this was also enhanced with oral metformin, significantly slowing tumor growth relative to unsensitized controls (p < 0.01). Microbubble sensitization was also shown to improve overall animal survival. Importantly, effects were found to be radiation dose-rate-dependent, reflecting the transient nature of tumor oxygenation. Full article

Halloysite nanoclay (HNC) was examined as an adsorbent for the individual and simultaneous removal of antibiotic enrofloxacin (ENRO) and methylene blue (MB) from aqueous solutions, alongside its regeneration via cold atmospheric plasma (CAP) bubbling. Initially, batch kinetics and isotherm studies were carried out, while the effect of several parameters was evaluated. Both ENRO and MB adsorption onto HNC was better described by Langmuir model, with its maximum adsorption capacity being 34.80 and 27.66 mg/g, respectively. A Pseudo-second order model fitted the experimental data satisfactorily, suggesting chemisorption (through electrostatic interactions) as the prevailing adsorption mechanism, whereas adsorption was also controlled by film diffusion. In the binary system, the presence of MB seemed to act antagonistically to the adsorption of ENRO. The saturated adsorbent was regenerated inside a CAP microbubble reactor and its adsorption capacity was re-tested by applying new adsorption cycles. CAP bubbling was able to efficiently regenerate saturated HNC with low energy requirements (16.67 Wh/g-adsorbent) in contrast to Fenton oxidation. Most importantly, the enhanced adsorption capacity of the CAP-regenerated HNC (compared to raw HNC), when applied in new adsorption cycles, indicated its activation during the regeneration process. The present study provides a green, sustainable and highly effective alternative for water remediation where pharmaceutical and dyes co-exist. Full article

Recently, dual-mode imaging systems merging magnetic resonance imaging (MRI) and ultrasound (US) have been developed. Designing a dual-mode contrast agent is complex due to different mechanisms of enhancement. Herein, we describe novel phase change nanodroplets (PCNDs) with perfluoropentane encapsulated in a pre-polyglycerol sebacate (pre-PGS) shell loaded with polyethylene glycol (PEG)-coated iron oxide nanoparticles as having a dual-mode contrast agent effect. Iron oxide nanoparticles were prepared via the chemical co-precipitation method and PCNDs were prepared via the solvent displacement technique. PCNDs showed excellent enhancement in the in vitro US much more than Sonovue^® microbubbles. Furthermore, they caused a susceptibility effect resulting in a reduction of signal intensity on MRI. An increase in the concentration of nanoparticles caused an increase in the MR contrast effect but a reduction in US intensity. The concentration of nanoparticles in a shell of PCNDs was optimized to obtain a dual-mode contrast effect. Biocompatibility, hemocompatibility, and immunogenicity assays showed that PCNDs were safe and non-immunogenic. Another finding was the dual-mode potential of unloaded PCNDs as T1 MR and US contrast agents. Results suggest the excellent potential of these PCNDs for use as dual-mode contrast agents for both MRI and US. Full article

Widely used classical angiography with the use of iodine contrast agents is highly problematic, particularly in patients with diabetes mellitus, cardiac and pulmonary diseases, or degree III or IV renal insufficiency. Some patients may be susceptible to allergic reaction to the iodine contrast substance. The intravenous injection of a bolus of CO₂ (negative contrast) is an alternative method, which is, however, currently only used for imaging blood vessels of the lower limbs. The aim of our project was to design and test on an animal model a methodology for injecting the CO₂ foam which would minimize the possibility of embolization of the brain tissue and heart infarction, leading to their damage. This is important research for the further promotion of the use of CO₂, which is increasingly important for endovascular diagnosis and treatment, because carbon-dioxide-related complications are extremely rare. CO₂ foam was prepared by the rapid mixing in a 2:1 ratio of CO₂ and fetal bovine serum (FBS)-enriched Dulbecco’s Modified Eagle Medium (DMEM). Freshly prepared CO₂ foam was administered into the catheterized rat tail vein or cannulated rat abdominal aorta and inferior vena cava (IVC). CO₂ foam was compared with commercially available microbubbles (lipid shell/gas core). The rat heart in its parasternal long axis was imaged in B-Mode and Non-linear Contrast Mode before/during and after the contrast administration. Samples of the brain, heart and lungs were collected and subjected to histological examination. The non-linear contrast imaging method enables the imaging of micron-sized gas microbubbles inside a rat heart. The significantly shorter lifetime of the prepared CO₂ foam is a benefit for avoiding the local ischemia of tissues. Full article

In this report, we investigate the infusion of carbon dioxide into a 3D-printable photosensitive polymer. The result is a carbonated polymer composite material. In use, polymer composite materials expect to succeed where ordinary polymers and metals fail. This is due to the tailorability of composite materials for specific applications. Usually, micro/nano-particulates are embedded as fillers within a polymer matrix, enhancing the overall material properties. Here, carbon dioxide (CO₂) microbubbles serve as the filler within a nylon-like polymer matrix. Additive manufacturing by stereolithography (SLA) of the carbonated polymer composite proved possible using the digital light projection (DLP) 3D printing technique. Post-heat treatment using thermogravimetric analysis of the samples at elevated temperatures resulted in a 33% mass reduction, indicative of nearly complete solvent removal and curing. An initial increase in polymer carbonation duration showed a 16% increase in porosity, more stable thermal profiles, and a 40% decrease in specific heat capacity. Thermo-mechanical compressive tests on an optimal carbonated sample revealed a 70% increase in compressive strength over its neat counterpart and a peak modulus at 50 °C of 60 MPa. Such 3D-printable carbonated polymer composites may find use in applications requiring high strength-to-weight ratio thermally stable polymers and applications requiring a versatile and convenient storage medium for on-demand CO₂ deposition or supercritical fluid phase transformation. Full article