Ultrasonic-assisted fabrication and release kinetics of two model redox-responsive magnetic microcapsules for hydrophobic drug delivery

Core-Shell Magnetic Particles: Tailored Synthesis and Applications

Core-shell magnetic particles consisting of magnetic core and functional shells have aroused widespread attention in multidisciplinary fields spanning chemistry, materials science, physics, biomedicine, and bioengineering due to their distinctive magnetic properties, tunable interface features, and elaborately designed compositions. In recent decades, various surface engineering strategies have been developed to endow them desired properties (e.g., surface hydrophilicity, roughness, acidity, target recognition) for efficient applications in catalysis, optical modulation, environmental remediation, biomedicine, etc. Moreover, precise control over the shell structure features like thickness, porosity, crystallinity and compositions including metal oxides, carbon, silica, polymers, and metal-organic frameworks (MOFs) has been developed as the major method to exploit new functional materials. In this review, we highlight the synthesis methods, regulating strategies, interface engineering, and applications of core-shell magnetic particles over the past half-century. The fundamental methodologies for controllable synthesis of core-shell magnetic materials with diverse organic, inorganic, or hybrid compositions, surface morphology, and interface property are thoroughly elucidated and summarized. In addition, the influences of the synthesis conditions on the physicochemical properties (e.g., dispersibility, stability, stimulus-responsiveness, and surface functionality) are also discussed to provide constructive insight and guidelines for designing core-shell magnetic particles in specific applications. The brand-new concept of "core-shell assembly chemistry" holds great application potential in bioimaging, diagnosis, micro/nanorobots, and smart catalysis. Finally, the remaining challenges, future research directions and new applications for the core-shell magnetic particles are predicted and proposed.

Optically monitoring the microenvironment of a hydrophobic cargo in amphiphilic nanogels: influence of network composition on loading and release

Amphiphilic nanogels (ANGs) are promising carriers for hydrophobic cargos such as drugs, dyes, and catalysts. Loading content and release kinetics of these compounds are controlled by type and number of hydrophobic groups in the amphiphilic copolymer network. Thus, understanding the interactions between cargo and colloidal carrier is mandatory for a tailor-made and cargo-specific ANG design. To systematically explore the influence of the network composition on these interactions, we prepared a set of ANGs of different amphiphilicity and loaded these ANGs with varying concentrations of the solvatochromic dye Nile Red (NR). Here, NR acts as a hydrophobic model cargo to optically probe the polarity of its microenvironment. Analysis of the NR emission spectra as well as measurements of the fluorescence quantum yields and decay kinetics revealed a decrease in the polarity of the NR microenvironment with increasing hydrophobicity of the hydrophobic groups in the ANG network and dye-dye interactions at higher loading concentrations. At low NR concentrations, the hydrophobic cargo NR is encapsulated in the hydrophobic domains. Increasing NR concentrations resulted in probe molecules located in a more hydrophilic environment, i.e., at the nanodomain border, and favored dye-dye interactions and NR aggregation. These results correlate well with release experiments, indicating first NR release from more hydrophilic network locations. Overall, our findings demonstrate the importance to understand carrier-drug interactions for efficient loading and controlled release profiles in amphiphilic nanogels.

Advances in protein-based microcapsules and their applications: A review

Due to their excellent emulsification, biocompatibility, and biological activity, proteins are widely used as microcapsule wall materials for encapsulating drugs, natural bioactive substances, essential oils, probiotics, etc. In this review, we summarize the protein-based microcapsules, discussing the types of proteins utilized in microcapsule wall materials, the preparation process, and the main factors that influence their properties. Additionally, we conclude with examples of the vital role of protein-based microcapsules in advancing the food industry from primary processing to deep processing and their potential applications in the biomedical, chemical, and textile industries. However, the low stability and controllability of protein wall materials lead to degraded performance and quality of microcapsules. Protein complexes with polysaccharides or modifications to proteins are often used to improve the thermal instability, pH sensitivity, encapsulation efficiency and antioxidant capacity of microcapsules. In addition, factors such as wall material composition, wall material ratio, the ratio of core to wall material, pH, and preparation method all play critical roles in the preparation and performance of microcapsules. The application area and scope of protein-based microcapsules can be further expanded by optimizing the preparation process and studying the microcapsule release mechanism and control strategy.

Metal-Organic Frameworks (MOF)-Assisted Sonodynamic Therapy in Anticancer Applications

Sonodynamic therapy (SDT) has emerged as a promising therapeutic modality for anticancer treatments and is becoming a cutting-edge interdisciplinary research field. This review starts with the latest developments of SDT and provides a brief comprehensive discussion on ultrasonic cavitation, sonodynamic effect, and sonosensitizers in order to popularize the basic principles and probable mechanisms of SDT. Then the recent progress of MOF-based sonosensitizers is overviewed, and the preparation methods and properties (e.g., morphology, structure, and size) of products are presented in a fundamental perspective. More importantly, many deep observations and understanding toward MOF-assisted SDT strategies were described in anticancer applications, aiming to highlight the advantages and improvements of MOF-augmented SDT and synergistic therapies. Last but not least, the review also pointed out the probable challenges and technological potential of MOF-assisted SDT for the future advance. In all, the discussions and summaries of MOF-based sonosensitizers and SDT strategies will promote the fast development of anticancer nanodrugs and biotechnologies.

Sonochemistry: An emerging approach to fabricate biopolymer cross-linked emulsions for the delivery of bioactive compounds

Sonochemistry shows remarkable potential in the synthesis or modification of new micro/nanomaterials, particularly the cross-linked emulsions for drug delivery. However, the trend of utilizing sonochemical emulsions for delivery of food-derived bioactive compounds has been just started. The extension of sonochemistry as a tool for engineering bioactive delivery systems will make the approach more universal and greatly increase its applications in the food industry. This review summarizes different types of biopolymeric cross-linked emulsions (CLEs) synthesized via sonochemical approach, including CLEs, surface-modified CLEs, cross-linked high internal phase emulsions, and some novel systems templated on CLEs. Special emphasis is directed toward the cross-linking mechanisms of biopolymers at the oil-water interfaces under acoustic cavitation and the physicochemical principles underlying sonochemical fabrication. We also highlight the advantages and challenges associated with the delivery performance of each system for bioactive compounds. The potential in delivering bioactives using sonochemical emulsions has not been fully reached. There are still a number of issues that need to be overcome, including low cross-linking degree of biopolymers, degradation of bioactives in sonochemical process, and unclear biological fate of encapsulated bioactive compounds. This review may guide future trends in exploring efficient sonochemical strategies and multifunctional delivery systems for food applications.

Update of ultrasound-assembling fabrication and biomedical applications for heterogeneous polymer composites

As a power-driving approach, ultrasound irradiation is very appealing to the preparation or modification of new materials. In the review, we overviewed the latest development of ultrasound-mediated effects or reactions in polymer composites, and demonstrated its unique and powerful aspects on the polymerization or aggregation. The review generalized the different categories of heterogeneous polymer composites by defining the constituents, and described the shapes, sizes and basic properties of various purpose-specific or site-specific products. Importantly, the review paid more attention to the main biomedicine applications of heterogeneous polymer composites, such as drug or bioactive substance entrapment, delivery, release, imaging, and therapy, and emphasized many advantages of ultrasound-assembling approaches and heterogeneous polymer composites in biology and medicine fields. In addition, the review also indicated the prospective challenges of heterogeneous polymer composites both in ultrasound-assembling designs and in biomedical applications.

Modeling of in vitro drug release from polymeric microparticle carriers

Incorporation of active substances in polymeric microparticles (microencapsulation) is an important technological strategy used in the pharmaceutical industry to improve the functionality, quality, safety and/or therapeutic efficiency of pharmaceutical preparations for different routes of administration. The current focus of research in this field is on the encapsulation of small molecules and macromolecules into microparticles based on biocompatible synthetic polymers and biopolymers, such as polypeptides and polysaccharides, in order to achieve preferable drug release kinetics and many other advantages. Diversity in the structure and size of microparticles, choice of polymers, and manufacturing processes, allows for designing a multitude of microcarriers (e.g., monolithic matrix microspheres, hollow microcapsules, water-or oil-core microcapsules, stimulus-sensitive microcapsules), whereby their impact on biopharmaceutical profile of drugs can be manipulated. The results so far indicate that the in vitro drug release kinetics evaluation is one of the key aspects of the microparticle-type carrier characterization, where the application of the mathematical analysis (modeling) of the drug release profiles is an important tool for elucidating drug release mechanisms, as well as for evaluating the influence and optimization of formulation and process parameters in the microencapsulation procedure. The article reviews representative studies in which mathematical modeling of experimentally obtained release data was performed for microencapsulated model drugs with different physicochemical properties, as well as the relevance and potential limitations of this approach.

Thermo/glutathione-sensitive release kinetics of heterogeneous magnetic micro-organogel prepared by sono-catalysis

To improve the loading and delivery for hydrophobic drugs and optimize the release efficiency in tumor microenvironment, a novel core-shell magnetic micro-organogel carrier was successfully prepared by a sono-catalysis process in the study. As-synthesized magnetic micro-organogel had an appropriate dispersibility in water owing to the hydrophilicity of protein shell and could be kept steadily with a well-defined spherical morphology owing to the three-dimensional gel structure of oil core, and it promised an accessible targeted drug delivery owing to its good magnetism-mediated motion ability. Moreover, the magnetic micro-organogel showed a high loading efficiency up to 94.22% for coumarin 6 which was dissolved into the micro-organogel as a model hydrophobic drug. More importantly, the release kinetics revealed that the magnetic micro-organogel had a thermo-sensitive and glutathione (GSH)-sensitive ability to control the drug release, and proved that its release mechanisms referred to the combination of erosion, diffusion and degradation.

A power-triggered preparation strategy of nano-structured inorganics: sonosynthesis

Ultrasound irradiation covers many chemical reactions crucially aiming to design and synthesize various structured materials as an enduring trend in frontier research studies. Here, we focus on the latest progress of ultrasound-assisted synthesis and present the basic principles or mechanisms of sonosynthesis (or sonochemical synthesis) from ultrasound irradiation in a brand new way, including primary sonosynthesis, secondary sonosynthesis, and synergetic sonosynthesis. This current review describes in detail the various sonochemical synthesis strategies for nano-structured inorganic materials and the unique aspects of products including the size, morphology, structure, and properties. In addition, the review points out the probable challenges and technological potential for future advancement. We hope that such a review can provide a comprehensive understanding of sonosynthesis and emphasize the great significance of structured materials synthesis as a power-induced strategy broadening the updated applications of ultrasound.

Ultrasound-mediated gene delivery into suspended plant cells using polyethyleneimine-coated mesoporous silica nanoparticles

Sonoporation, ultrasound-mediated membrane perforation can potentially puncture plasma membrane and rigid cell wall on presumably reversible basis which benefit gene transfection and plant biotechnology. Herein, positively charged poly-ethyleneimine (PEI)-coated mesoporous silica nanoparticles (MSNs) with an average diameter of 100 ± 8.7 nm was synthesized for GUS-encoding plasmid delivery into the suspended tobacco cells using the ultrasound treatment. The overall potential of PEI-MSN for DNA adsorption was measured at 43.43 μg DNA mg-1 PEI-MSNs. It was shown that high level of sonoporation may adversely upset the cell viability. Optimal conditions of ultrasonic treatment are obtained as 8 min at 3 various intensities of 160, 320 and 640 W. Histochemical staining assay was used to follow the protein expression. It was shown that PEI-coated MSNs efficiently transfer the GUS-encoding plasmid DNA into the tobacco cells. The results of this study showed that ultrasonic treatment provides an economical and straightforward approach for gene transferring into the plant cells without any need to complicated devices and concerns about safety issues.

Sonochemical fabrication of inorganic nanoparticles for applications in catalysis

Catalysis covers almost all the chemical reactions or processes aiming for many applications. Sonochemistry has emerged in designing and developing the synthesis of nano-structured materials, and the latest progress mainly focuses on the synthetic strategies, product properties as well as catalytic applications. This current review simply presents the sonochemical effects under ultrasound irradiation, roughly describes the ultrasound-synthesized inorganic nano-materials, and highlights the sonochemistry applications in the inorganics-based catalysis processes including reduction, oxidation, degradation, polymerization, etc. Or all in all, the review hopes to provide an integrated understanding of sonochemistry, emphasize the great significance of ultrasound-assisted synthesis in structured materials as a unique strategy, and broaden the updated applications of ultrasound irradiation in the catalysis fields.

Sonochemical catalysis as a unique strategy for the fabrication of nano-/micro-structured inorganics

Ultrasound-assisted approaches, as an important trend in material synthesis, have emerged for designing and creating nano-/micro-structures. This review simply presents the basic principles of ultrasound irradiation including acoustic cavitation, sonochemical effects, physical and/or mechanical effects, and on the basis of the latest progress, it newly summarizes sonochemical catalysis for the fabrication of nano-structured or micro-structured inorganic materials such as metals, alloys, metal compounds, non-metal materials, and inorganic composites, where the theories or mechanisms of catalytic synthetic routes, and the morphologies, structures, sizes, properties and applications of products are described in detail. In the review, a few technological potentials and probable challenges of sonochemical catalysis are also highlighted for the future advance of synthesis methods. Therefore, sonochemical catalysis or ultrasound-assisted synthesis will serve as a unique strategy to reveal its great significance in material fabrication.

Scalable fabrication of tunable titanium nanotubes via sonoelectrochemical process for biomedical applications

Titanium does not react well with the human tissues and due to its bio-inert nature the surface modification has yet to be well-studied. In this study, the sonoelectrochemical process has been carried out to generate TiO₂ nanotube arrays on implantable Ti 6-4. All the prepared nanotubes fill with the vancomycin by immersion and electrophoresis method. Drug-releasing properties, antibacterial behavior, protein adsorption and cell attachment of drug-modified nanotubes are examined by UV-vis, flow cytometry, modified disc diffusion, BSA adsorption, and FESEM, respectively. The most uniform morphology, appropriate drug release, cell viability behavior and antibacterial properties can be achieved by samples anodized in the range of 60-75 V. Also improves the adsorption of BSA protein in bone healing and promotes osteoblast activity and osseointegration. Drug loading efficiency increases up to 60% via electrophoresis comparing the immersion method for anodized sample in 75 V. While electrophoresis does not affect the amount of vancomycin adsorption for lower voltages. Besides, the present study indicates that an anodized sample without drug loading has no antibacterial activity. Moreover, 28-days drug releasing from nanotubes is investigated by mathematical formula according to Fickian's law to find an effective dose of loaded drug.

Barrera E. Development of Functionalized Carbon Nano-Onions Reinforced Zein Protein Hydrogel Interfaces for Controlled Drug Release

In the current study, poly 4-mercaptophenyl methacrylate-carbon nano-onions (PMPMA-CNOs = f-CNOs) reinforced natural protein (zein) composites (zein/f-CNOs) are fabricated using the acoustic cavitation technique. The influence of f-CNOs inclusion on the microstructural properties, morphology, mechanical, cytocompatibility, in-vitro degradation, and swelling behavior of the hydrogels are studied. The tensile results showed that zein/f-CNOs hydrogels fabricated by the acoustic cavitation system exhibited good tensile strength (90.18 MPa), compared with the hydrogels fabricated by the traditional method and only microwave radiation method. It reveals the magnitude of physisorption and degree of colloidal stability of f-CNOs within the zein matrix under acoustic cavitation conditions. The swelling behaviors of hydrogels were also tested and improved results were noticed. The cytotoxicity of hydrogels was tested with osteoblast cells. The results showed good cell viability and cell growth. To explore the efficacy of hydrogels as drug transporters, 5-fluorouracil (5-FU) release was measured under gastric and intestinal pH environment. The results showed pH-responsive sustained drug release over 15 days of study, and pH 7.4 showed a more rapid drug release than pH 2.0 and 4.5. Nonetheless, all the results suggest that zein/f-CNOs hydrogel could be a potential pH-responsive drug transporter for a colon-selective delivery system.