Recent Development on Transition Metal Oxides-Based Core-Shell Structures for Boosted Energy Density Supercapacitors

In recent years, nanomaterials exploration and synthesis have played a crucial role in advancing energy storage research, particularly in supercapacitor development. Researchers have diversified materials, including metal oxides, chalcogenides, and composites, as well as carbon materials, to enhance energy and power density. Balancing energy density with electrochemical stability remains challenging, driving intensified efforts in advancing electrode materials. This review focuses on recent progress in designing and synthesizing core-shell materials tailored for supercapacitors. The core-shell architecture offers advantages such as increased surface area, redox active sites, electrical conductivity, ion diffusion kinetics, specific capacitance, and cyclability. The review explores the impact of core and shell materials, specifically transition metal oxides (TMOs), on supercapacitor electrochemical behavior. Metal oxide choices, such as cobalt oxide as a preferred core and manganese oxide as a shell, are discussed. The review also highlights characterization techniques for assessing structural, morphological, and electrochemical properties of core-shell materials. Overall, it provides a comprehensive overview of ongoing TMOs-based core-shell material research for supercapacitors, showcasing their potential to enhance energy storage for applications ranging from gadgets to electric vehicles. The review outlines existing challenges and future opportunities in evolving TMOs-based core-shell materials for supercapacitor advancements, holding promise for high-efficiency energy storage devices.

Porous Microspheres as Pathogen Traps for Sepsis Therapy: Capturing Active Pathogens and Alleviating Inflammatory Reactions

Sepsis is a systemic inflammatory response syndrome caused by pathogen infection, while the current antibiotics mainly utilized in clinical practice to combat infection result in the release of pathogen-associated molecular patterns (PAMPs) in the body. Herein, we provide an innovative strategy for controlling sepsis, namely, capturing active pathogens by means of extracorporeal blood purification. Carbon nanotubes (CNTs) were modified with dimethyldiallylammonium chloride (DDA) through γ-ray irradiation-induced graft polymerization to confer a positive charge. Then, CNT-DDAs are blended with polyurethane (PU) to prepare porous microspheres using the electro-spraying method. The obtained microspheres with a pore diameter of 2 μm served as pathogen traps and are termed as PU-CNT-DDA microspheres. Even at a high flow rate of 50 mL·min-1, the capture efficiencies of the PU-CNT-DDAs for Escherichia coli and Staphylococcus aureus remained 94.7% and 98.8%, respectively. This approach circumvents pathogen lysis and mortality, significantly curtails the release of PAMPs, and hampers the production of pro-inflammatory cytokines. Therefore, hemoperfusion using porous PU-CNT-DDAs as pathogen traps to capture active pathogens and alleviate inflammation opens a new route for sepsis therapy.

Core-Shell Particles: From Fabrication Methods to Diverse Manipulation Techniques

Core-shell particles are micro- or nanoparticles with solid, liquid, or gas cores encapsulated by protective solid shells. The unique composition of core and shell materials imparts smart properties on the particles. Core-shell particles are gaining increasing attention as tuneable and versatile carriers for pharmaceutical and biomedical applications including targeted drug delivery, controlled drug release, and biosensing. This review provides an overview of fabrication methods for core-shell particles followed by a brief discussion of their application and a detailed analysis of their manipulation including assembly, sorting, and triggered release. We compile current methodologies employed for manipulation of core-shell particles and demonstrate how existing methods of assembly and sorting micro/nanospheres can be adopted or modified for core-shell particles. Various triggered release approaches for diagnostics and drug delivery are also discussed in detail.

Preparation and pH Detection Performance of Rosin-Based Fluorescent Polyurethane Microspheres

Rosin-based fluorescent polyurethane emulsion (FPU) was prepared using isophorone diisocyanate, ester of acrylic rosin and glycidyl methacrylate, 1,5-dihydroxy naphthalene (1,5-DN), and 1,4-butanediol as the raw materials. Then, rosin-based fluorescent polyurethane microspheres (FPUMs) were successfully prepared by suspension polymerization method using FPU as the main material, azodiisobutyronitrile as the initiator, and gelatin as the dispersant. FPUMs were characterized by Fourier transform infrared spectra, thermogravimetric analysis, optical microscopy, scanning electron microscopy and fluorescence spectra, and the response performance of FPUMs to pH was studied. The results showed that FPUMs were successfully prepared. With the increase of the level of 1,5-DN, the particle size of FPUMs increased gradually, and the fluorescence intensity increased first and then decreased. When the level of 1,5-DN was 3 wt.%, the average particle size was 49.3 μm, the particle distribution index (PDI) was 1.05, and the fluorescence intensity was the largest (3662 a.u.). The fluorescence intensity of FPUMs increased linearly with the decrease of pH, which can be used for pH detection in solution. Furthermore, the FPUMs exhibited good thermal stability, anti-interference and recoverability.

Functional microspheres for tissue regeneration

As a new type of injectable biomaterials, functional microspheres have attracted increasing attention in tissue regeneration because they possess some advantageous properties compared to other biomaterials, including hydrogels. A variety of bio-inspired microspheres with unique structures and properties have been developed as cellular carriers and drug delivery vehicles in recent years. In this review, we provide a comprehensive summary of the progress of functional and biodegradable microspheres that have been used for tissue regeneration over the last two decades. First, we briefly introduce the biomaterials and general methods for microsphere fabrication. Next, we focus on the newly developed technologies for preparing functional microspheres, including macroporous microspheres, nanofibrous microspheres, hollow microspheres, core-shell structured microspheres, and surface-modified functional microspheres. After that, we discuss the application of functional microspheres for tissue regeneration, specifically for bone, cartilage, dental, neural, cardiac, and skin tissue regeneration. Last, we present our perspectives and future directions of functional microspheres as injectable carriers for the future advancement of tissue regeneration.

Development, Optimization, and Pharmacokinetics Study of Bufalin/Nintedanib Co-loaded Modified Albumin Sub-microparticles Fabricated by Coaxial Electrostatic Spray Technology

Coaxial electrostatic spray technology has received extensive attention in fabricating micro/nanoparticles for drug delivery. However, there are few reports on applying this technology in preparing albumin nanoparticles. In this study, the bufalin (BF) and nintedanib (NDNB) co-loaded ursodeoxycholic acid and p-biguanides benzoic acid decorated albumin sub-microparticles (BN-DUB subMPs) were fabricated by coaxial electrostatic spray technology and optimized by central composite design. Five percent of albumin (contained 0.7% polyethylene oxide) solution was selected as the shell solution which ejected through outer axis with the flow rate of 0.07 mm/min, while the core solution which contained by BF and NDNB ethanol solution was ejected through inner axis with the flow rate of 0.05 mm/min. In vitro cell studies revealed that the modified albumin possessed good biocompatibility. What's more, the BN-DUB subMPs enhanced the inhibitory effect on the growth of LLC cells efficiently. The pharmacokinetics study showed that the t_1/2 and AUC_0-t of BN-DUB subMPs increased significantly compared with that of the drug solution, which indicated the improved in vivo stability of modified albumin nanoparticles. Thus, this study provided a novel and simple technical platform for the development of albumin-based drug carriers.

Template-Free Construction of Tin Oxide Porous Hollow Microspheres for Room-Temperature Gas Sensors

Porous hollow microsphere (PHM) materials represent ideal building blocks for realizing diverse functional applications such as catalysis, energy storage, drug delivery, and chemical sensing. This has stimulated intense efforts to construct metal oxide PHMs for achieving highly sensitive and low-power-consumption semiconductor gas sensors. Conventional methods for constructing PHMs rely on delicate reprogramming of templates and may suffer from the structural collapse issue during the removal of templates. Here, we propose a template-free method for the construction of tin oxide (SnO₂) PHMs via the competition between the solvent evaporation rate and the phase separation dynamics of colloidal SnO₂ quantum wires. The SnO₂ PHMs (typically 3 ± 0.5 μm diameter and approximately 200 nm shell thickness) exhibit desirable structural stability with desirable processing compatibility with various substrates. This enables the realization of NO₂ gas sensors having a superior response and recovery process at room temperature. The superior NO₂-sensing characteristic is attributed to the effective gas adsorption competition on solid surfaces benefiting from efficient diffusion channels, enhancing the interaction of metal oxide solids with gas molecules in terms of the receptor function, transducer function, and utility factor. In addition, the one-step deposition of SnO₂ PHMs directly onto device substrates simplifies the fabrication conditions for semiconductor gas sensors. The desirable structural stability of PHMs combined with the functional diversity of metal oxides may open new opportunities for the design of functional materials and devices.

Polymeric hollow microcapsules (PHM) via cellulose nanocrystal stabilized Pickering emulsion polymerization

A practical and sustainable method to prepare polymeric hollow microcapsules (PHMs) using cellulose nanocrystal (CNC) stabilized Pickering emulsion polymerization was developed. Pristine CNCs hydrolyzed from wood pulp are hydrophilic and could be employed as emulsifiers to prepare oil-in-water (O/W) Pickering emulsions. The O/W Pickering emulsions were used as templates for the Pickering emulsion polymerization of hydrophobic monomers inside the emulsion droplets. The crosslinked hydrophobic polymers phase separated and partitioned to the interface of the Pickering emulsion, leading to the formation of hydrophobic PHMs. Correspondingly, cinnamate modified CNCs with less surface hydrophilicity were employed as emulsifiers to obtain water-in-oil (W/O) inverse Pickering emulsions, which were then used as templates for inverse Pickering emulsion polymerization of hydrophilic monomers to prepare hydrophilic PHMs. Therefore, both hydrophobic and hydrophilic PHMs could be obtained via this approach. Herein, polystyrene, poly(4-vinylpyridine), and poly(N-isopropyl acrylamide) hollow microcapsules were prepared as models, where the size, crosslinking density, shell structure and stimuli-responsive properties of PHMs could be tuned by varying the synthesis parameters.