Remote targeted implantation of sound-sensitive biodegradable multi-cavity microparticles with focused ultrasound

Sonosensitive Cavitation Nuclei-A Customisable Platform Technology for Enhanced Therapeutic Delivery

Ultrasound-mediated cavitation shows great promise for improving targeted drug delivery across a range of clinical applications. Cavitation nuclei-sound-sensitive constructs that enhance cavitation activity at lower pressures-have become a powerful adjuvant to ultrasound-based treatments, and more recently emerged as a drug delivery vehicle in their own right. The unique combination of physical, biological, and chemical effects that occur around these structures, as well as their varied compositions and morphologies, make cavitation nuclei an attractive platform for creating delivery systems tuned to particular therapeutics. In this review, we describe the structure and function of cavitation nuclei, approaches to their functionalization and customization, various clinical applications, progress toward real-world translation, and future directions for the field.

Adoptive macrophage directed photodynamic therapy of multidrug-resistant bacterial infection

Multidrug-resistant (MDR) bacteria cause severe clinical infections and a high mortality rate of over 40% in patients with immunodeficiencies. Therefore, more effective, broad-spectrum, and accurate treatment for severe cases of infection is urgently needed. Here, we present an adoptive transfer of macrophages loaded with a near-infrared photosensitizer (Lyso700D) in lysosomes to boost innate immunity and capture and eliminate bacteria through a photodynamic effect. In this design, the macrophages can track and capture bacteria into the lysosomes through innate immunity, thereby delivering the photosensitizer to the bacteria within a single lysosome, maximizing the photodynamic effect and minimizing the side effects. Our results demonstrate that this therapeutic strategy eliminated MDR Staphylococcus aureus (MRSA) and Acinetobacter baumannii (AB) efficiently and cured infected mice in both two models with 100% survival compared to 10% in the control groups. Promisingly, in a rat model of central nervous system bacterial infection, we performed the therapy using bone marrow-divided macrophages and implanted glass fiber to conduct light irradiation through the lumbar cistern. 100% of infected rats survived while none of the control group survived. Our work proposes an efaficient and safe strategy to cure MDR bacterial infections, which may benefit the future clinical treatment of infection.

A review of protein-protein interaction and signaling pathway of Vimentin in cell regulation, morphology and cell differentiation in normal cells

The Vimentin intermediate filament (VIF) is an essential cytoskeleton component. It shows dynamically changing expression patterns throughout various phases of the differentiation process, suggesting that the protein is physiologically important. Vimentin's essential functions have recently been clear, so Vimentin-deficient of animals was described as a change of morphology and signaling pathway. Recent research has discovered many vital roles for Vimentin that were previously unknown. VIF emerges as an organizer of many essential proteins involved in movement and cell signaling. The highly dynamic and complicated phosphorylation of VIF seems to be a regulator mechanism for various activities. Changes in IF expression patterns are often linked with cancer progression, especially those leading to enhanced invasion and cellular migration. This review will discuss the function of Vimentin intermediate filaments in normal cell physiology, cell adhesion structures, cell shape, and signaling pathways. The genes interaction and gene network linked with Vimentin will be discussed in more studies. However, research aimed at understanding the function of Vimentin in different signaling cascades and gene interactions might offer novel methods for creating therapeutic medicines. Enrichr GEO datasets used gene ontology (GO) and pathway enrichment analyses. STRING online was used to predict the functional connections of proteins-proteins, followed by Cytoscape analysis to find the master genes. Cytoscape and STRING research revealed that eight genes, Fas, Casp8, Casp6, Fadd, Ripk1, Des, Tnnc2, and Tnnt3, were required for protein-protein interactions with Vimentin genes involved in cell differentiation.

Gas-stabilizing nanoparticles for ultrasound imaging and therapy of cancer

The use of ultrasound in the clinic has been long established for cancer detection and image-guided tissue biopsies. In addition, ultrasound-based methods have been widely explored to develop more effective cancer therapies such as localized drug delivery, sonodynamic therapy, and focused ultrasound surgery. Stabilized fluorocarbon microbubbles have been in use as contrast agents for ultrasound imaging in the clinic for several decades. It is also known that microbubble cavitation could generate thermal, mechanical, and chemical effects in the tissue to improve ultrasound-based therapies. However, the large size, poor stability, and short-term cavitation activity of microbubbles limit their applications in cancer imaging and therapy. This review will focus on an alternative type of ultrasound responsive material; gas-stabilizing nanoparticles, which can address the limitations of microbubbles with their nanoscale size, robustness, and high cavitation activity. This review will be of interest to researchers who wish to explore new agents to develop improved methods for molecular ultrasound imaging and therapy of cancer.

Unsupported gold nanocones as sonocatalytic agents with enhanced catalytic properties

Gold catalysts have attracted attention for enabling sustainable chemical processes under ambient conditions. This reactivity is attributed to the small size of the catalysts (<5 nm); however, their size also creates difficulty when removing from product streams and often require rare-metal additives to enhance reaction rate kinetics, thereby limiting the environmental benefits of these catalysts. Comparatively, submicron gold catalysts are easier to separate but are much less reactive under ambient conditions. In this study, we synthesized submicron gas-stabilising gold nanocones (gs-AuNCs) that are acoustically responsive to afford greater reaction rates than other conventional gold catalysts. We explore the catalytic performance of acoustically responsive gs-AuNCs exposed to focussed ultrasound at 5.0 MPa peak negative pressure and 1.1 MHz center frequency. Cavitation nucleated from gs-AuNCs significantly increased the sonocatalytic degradation of water pollutants without the need for co-catalysts. The ability to amplify catalysis with ultrasound by tailoring the morphology of the catalyst to control cavitation opens new paths for future designs of sonocatalysts that may enable a sustainable chemical approach needed for a broad range of industrial processes.

Applications of Ultrasound-Mediated Drug Delivery and Gene Therapy

Gene therapy has continuously evolved throughout the years since its first proposal to develop more specific and effective transfection, capable of treating a myriad of health conditions. Viral vectors are some of the most common and most efficient vehicles for gene transfer. However, the safe and effective delivery of gene therapy remains a major obstacle. Ultrasound contrast agents in the form of microbubbles have provided a unique solution to fulfill the need to shield the vectors from the host immune system and the need for site specific targeted therapy. Since the discovery of the biophysical and biological effects of microbubble sonification, multiple developments have been made to enhance its applicability in targeted drug delivery. The concurrent development of viral vectors and recent research on dual vector strategies have shown promising results. This review will explore the mechanisms and recent advancements in the knowledge of ultrasound-mediated microbubbles in targeting gene and drug therapy.

Investigating the Acoustic Response and Contrast Enhancement of Drug-Loadable PLGA Microparticles with Various Shapes and Morphologies

Polymer nanoparticles and microparticles have been used primarily for drug delivery. There is now growing interest in further developing polymer-based solid cavitation agents to also enhance ultrasound imaging. We previously reported on a facile method to produce hollow poly(lactic-co-glycolic acid) (PLGA) microparticles with different diameters and degrees of porosity. Here, we investigate the cavitation response from these PLGA microparticles with both therapeutic and diagnostic ultrasound transducers. Interestingly, all formulations exhibited stable cavitation; larger porous and multicavity particles also provided inertial cavitation at elevated acoustic pressure amplitudes. These larger particles also achieved contrast enhancement comparable to that of commercially available ultrasound contrast agents, with a maximum recorded contrast-to-tissue ratio of 28 dB. Therefore, we found that multicavity PLGA microparticles respond to both therapeutic and diagnostic ultrasound and may be applied as a theranostic agent.

Tailor-Made Single-Core PLGA Microbubbles as Acoustic Cavitation Enhancers for Therapeutic Applications

Microbubbles (MBs), being gas bubbles encapsulated inside a solid shell, have been investigated extensively in the field of therapeutic ultrasound as acoustic cavitation enhancers. Hard-shell MBs have an advantage over soft-shell MBs due to their improved stability. Poly(lactic-co-glycolic acid) (PLGA) is one of the most attractive polymers for hard-shell MB synthesis; however, very little is known regarding the effect of synthesis parameters on the acoustic cavitation activity of PLGA MBs and the tunability of this activity. In this study, by manipulating the synthesis parameters, we were able to control the characteristics of the MBs, such as their internal structure, gas core, size distribution, and shell thickness, which significantly affect the total acoustic cavitation activity that they exhibit (i.e., their cavitation dose). We showed that single-core MBs filled with C₃F₈ gas can produce cavitation effects for extended periods under continuous circulation. These MBs exhibited high stability, and their cavitation activity was not affected by prior circulation in the system. Preliminary in vivo results demonstrated that intravenously injected MBs did not cause adverse effects and produced cavitation activity that increased the permeability of the pig blood-brain barrier. Although more tests should be performed to evaluate the MB long-term safety and activity in vivo, these encouraging results suggest that our PLGA MBs have potential for future therapeutic applications as cavitation enhancers.

Ultrasonic Implantation and Imaging of Sound-Sensitive Theranostic Agents for the Treatment of Arterial Inflammation

For site-specific diseases such as atherosclerosis, it is desirable to noninvasively and locally deliver therapeutics for extended periods of time. High-intensity focused ultrasound (HIFU) provides targeted drug delivery, yet remains unable to sustain delivery beyond the HIFU treatment time. Furthermore, methods to validate HIFU-enhanced drug delivery remain limited. In this study, we report on HIFU-targeted implantation of degradable drug-loaded sound-sensitive multicavity PLGA microparticles (mcPLGA MPs) as a theranostic agent for the treatment of arterial lesions. Once implanted into the targeted tissue, mcPLGA MPs eluted dexamethasone for several days, thereby reducing inflammatory markers linked to oxidized lipid uptake in a foam cell spheroid model. Furthermore, implanted mcPLGA MPs created hyperechoic regions on diagnostic ultrasound images, and thus noninvasively verified that the target region was treated with the theranostic agents. This novel and innovative multifunctional theranostic platform may serve as a promising candidate for noninvasive imaging and treatment for site-specific diseases such as atherosclerosis.

Nanostructured TiO2 cavitation agents for dual-modal sonophotocatalysis with pulsed ultrasound

Current sonochemical methods rely on spatially uncontrolled cavitation for radical species generation to promote chemical reactions. To improve radical generation, sonosensitizers have been demonstrated to be activated by cavitation-based light emission (sonoluminescence). Unfortunately, this process remains relatively inefficient compared to direct photocatalysis, due to the physical separation between cavitation event and sonosensitizing agent. In this study, we have synthesized nanostructured titanium dioxide particles to couple the source for cavitation within a photocatalytic site to create a sonophotocatalyst. In doing so, we demonstrate that site-controlled cavitation from the nanoparticles using pulsed ultrasound at reduced acoustic powers resulted in the sonochemical degradation methylene blue at rates nearly three orders of magnitude faster than other titanium dioxide-based nanoparticles by conventional methods. Sonochemical degradation was directly proportional to the measured cavitation produced by these sonophotocatalysts. Our work suggests that simple nanostructuring of current sonosensitizers to enable on-site cavitation greatly enhances sonochemical reaction rates.

Influence of High Intensity Focused Ultrasound on the Microstructure and c-di-GMP Signaling of Pseudomonas aeruginosa Biofilms

Bacterial biofilms are typically more tolerant to antimicrobials compared to bacteria in the planktonic phase and therefore require alternative treatment approaches. Mechanical biofilm disruption from ultrasound may be such an alternative by circumventing rapid biofilm adaptation to antimicrobial agents. Although ultrasound facilitates biofilm dispersal and may enhance the effectiveness of antimicrobial agents, the resulting biological response of bacteria within the biofilms remains poorly understood. To address this question, we investigated the microstructural effects of Pseudomonas aeruginosa biofilms exposed to high intensity focused ultrasound (HIFU) at different acoustic pressures and the subsequent biological response. Confocal microscopy images indicated a clear microstructural response at peak negative pressures equal to or greater than 3.5 MPa. In this pressure amplitude range, HIFU partially reduced the biomass of cells and eroded exopolysaccharides from the biofilm. These pressures also elicited a biological response; we observed an increase in a biomarker for biofilm development (cyclic-di-GMP) proportional to ultrasound induced biofilm removal. Cyclic-di-GMP overproducing mutant strains were also more resilient to disruption from HIFU at these pressures. The biological response was further evidenced by an increase in the relative abundance of cyclic-di-GMP overproducing variants present in the biofilm after exposure to HIFU. Our results, therefore, suggest that both physical and biological effects of ultrasound on bacterial biofilms must be considered in future studies.

Nanomagnetite-embedded PLGA Spheres for Multipurpose Medical Applications

We report on the synthesis and evaluation of biopolymeric spheres of poly(lactide-co-glycolide) containing different amounts of magnetite nanoparticles and Ibuprofen (PLGA-Fe₃O₄-IBUP), but also chitosan (PLGA-CS-Fe₃O₄-IBUP), to be considered as drug delivery systems. Besides morphological, structural, and compositional characterizations, the PLGA-Fe₃O₄-IBUP composite microspheres were subjected to drug release studies, performed both under biomimetically-simulated dynamic conditions and under external radiofrequency magnetic fields. The experimental data resulted by performing the drug release studies evidenced that PLGA-Fe₃O₄-IBUP microspheres with the lowest contents of Fe₃O₄ nanoparticles are optimal candidates for triggered drug release under external stimulation related to hyperthermia effect. The as-selected microspheres and their chitosan-containing counterparts were biologically assessed on macrophage cultures, being evaluated as biocompatible and bioactive materials that are able to promote cellular adhesion and proliferation. The composite biopolymeric spheres resulted in inhibited microbial growth and biofilm formation, as assessed against Staphylococcus aureus, Pseudomonas aeruginosa, and Candida albicans microbial strains. Significantly improved antimicrobial effects were reported in the case of chitosan-containing biomaterials, regardless of the microorganisms' type. The nanostructured composite biopolymeric spheres evidenced proper characteristics as prolonged and controlled drug release platforms for multipurpose biomedical applications.