A fast and facile platform for fabricating phase-change materials-based drug carriers powered by chemical Marangoni effect

Top-down curing to construct self-retaining and moisture-pumping double-layered dressing with enhanced antibacterial, hemostatic, and wound healing performances

Continuous microenvironment modulation is an ongoing challenge in wound dressing, which includes excessive exudate absorption, oxygen delivery, bacterial inhibition and angiogenesis. Herein, we developed an in situ construction strategy to fabricate a self-retaining double-layered wound dressing, where the top layer precursor was composed of Ca2+-containing polyvinyl butyral (PVB) solution dispersed with hydroxypropyl methylcellulose (HPMC) particles, and the bottom one consisted of sodium alginate (Alg) solution blended with Ag-doped mesoporous bioactive glass powders (Ag-MBG). When in use, both precursors were simultaneously squeezed out from the twin nozzles connected to the individual chambers of a twin-chambered syringe, whereby Ca2+ in the top layer rapidly migrated downwards to crosslink Alg in the bottom layer, leading to the formation of an Alg/Ag-MBG (AA) functional hydrogel for filling an irregular wound. Meanwhile, with the rapid evaporation of low-boiling solvents, the top layer changed into a PVB/HPMC (PH) membrane covering the AA hydrogel and adhering to the surrounding healthy skin to fix the dressing. Practically, HPMC particles in the top layer acting as "micropumps" could drain the wound exudate out, while Ag-MBG in the bottom layer endowed the dressing with anti-bacterial, hemostatic, and pro-healing functions. The integrally constructed PH-AA dressing achieved over 99% bacterial elimination against both E. coli and S. aureus. Biological assessments indicated that the double-layered dressing possessed excellent biocompatibility and enhanced wound healing, demonstrating a wound closure rate of >97% at day 15. This study provides a facile method to directly construct multi-layer dressings on wounds to meet various wound care requirements.

Self-propulsion of a droplet induced by combined diffusiophoresis and Marangoni effects

Chemically active droplets display complex self-propulsion behavior in homogeneous surfactant solutions, often influenced by the interplay between diffusiophoresis and Marangoni effects. Previous studies have primarily considered these effects separately or assumed axisymmetric motion. To understand the full hydrodynamics, we investigate the motion of a two-dimensional active droplet under their combined influences using weakly nonlinear analysis and numerical simulations. The impact of two key factors, the Péclet number (P e $Pe$ ) and the mobility ratio between diffusiophoretic and Marangoni effects ( m $m$ ), on droplet motion is explored. We establish a phase diagram in theP e - m $Pe-m$ space, categorizing the boundaries between four types of droplet states: stationary, steady motion, periodic/quasi-periodic motion, and chaotic motion. We find that the mobility ratio does not affect the criticalP e $Pe$ for the onset of self-propulsion, but it significantly influences the stability of high-wavenumber modes as well as the droplet's velocity and trajectory. Scaling analysis reveals that in the highP e $Pe$ regime, the Marangoni and diffusiophoresis effects lead to distinct velocity scaling laws:U ∼ P e - 1 / 2 $U\sim Pe^{-1/2}$ andU ∼ P e - 1 / 3 $U\sim Pe^{-1/3}$ , respectively. When these effects are combined, the velocity scaling depends on the sign of the mobility ratio. In cases with a positive mobility ratio, the Marangoni effect dominates the scaling, whereas the negative diffusiophoretic effect leads to an increased thickness of the concentration boundary layer and a flattened scaling of the droplet velocity.

Cell-Based Micro/Nano-Robots for Biomedical Applications: A Review

Micro/nano-robots are powerful tools for biomedical applications and are applied in disease diagnosis, tumor imaging, drug delivery, and targeted therapy. Among the various types of micro-robots, cell-based micro-robots exhibit unique properties because of their different cell sources. In combination with various actuation methods, particularly externally propelled methods, cell-based microrobots have enormous potential for biomedical applications. This review introduces recent progress and applications of cell-based micro/nano-robots. Different actuation methods for micro/nano-robots are summarized, and cell-based micro-robots with different cell templates are introduced. Furthermore, the review focuses on the combination of cell-based micro/nano-robots with precise control using different external fields. Potential challenges, further prospects, and clinical translations are also discussed.

Applications of phase change materials in smart drug delivery for cancer treatment

Phase change materials (PCMs) are materials that are stimulated by the external enthalpy change (temperature) to realize solid-liquid and liquid-solid phase transformation. Due to temperature sensitivity, friendly modification, and low toxicity, PCMs have been widely used in smart drug delivery. More often than not, the drug was encapsulated in a solid PCMs matrix, a thermally responsive material. After the trigger implementation, PCMs change into a solid-liquid phase, and the loading drug is released accordingly. Therefore, PCMs can achieve precise release control with different temperature adjustments, which is especially important for small molecular drugs with severe side effects. The combination of drug therapy and hyperthermia through PCMs can achieve more accurate and effective treatment of tumor target areas. This study briefly summarizes the latest developments on PCMs as smart gate-keepers for anti-tumor applications in light of PCMs becoming a research hot spot in the nanomedicine sector in recent years.

A Light-Powered Triboelectric Nanogenerator Based on the Photothermal Marangoni Effect

The photothermal Marangoni effect enables direct light-to-work conversion, which is significant for realizing the self-propulsion of objects in a noncontact, controllable, and continuous manner. Many promising applications have been demonstrated in micro- and nanomachines, light-driven actuators, cargo transport, and gear transmission. Currently, the related studies about photothermal Marangoni effect-induced self-propulsion, especially rotational motions, remain focused on developing the novel photothermal materials, the structural designs, and the controllable self-propulsion modes. However, extending the related research from the laboratory practice to practical application remains a challenge. Herein, we combined the photothermal Marangoni effect-induced self-propulsion with the triboelectric nanogenerator technology for sunlight intensity determination. Photothermal black silicon, superhydrophobic copper foam with drag-reducing property, and triboelectric polytetrafluoroethylene film were integrated to fabricate a triboelectric nanogenerator. The photothermal-Marangoni-driven triboelectric nanogenerator (PMD-TENG) utilizes the photothermal Marangoni effect-induced self-propulsion to realize the relative motion between the triboelectric layer and the electrode, converting light into electrical signals, with a peak value of 2.35 V. The period of the output electrical signal has an excellent linear relationship with the light intensity. The accessible electrical signal generation strategy proposed here provides a new application for the photothermal Marangoni effect, which could further inspire the practical applications of the self-powered system based on the photothermal Marangoni effect, such as intelligent farming.

Updated results on the integration of metal-organic framework with functional materials toward n-alkane for latent heat retention and reliability

Phase change composites are in high demand in thermal management systems. Various supporting materials, including nanocomposites, have been employed to develop shape-stable phase change materials (PCMs). As the reliability of most composite materials has mostly been studied right after the preparation with specific thermal cycling measurements, it is difficult to analyze the long-term leakage-resistance capability and energy retention capacity. Additionally, achieving multifunctional phase change composites is a significant challenge for single supporting materials. Herein, we provide a follow-up report on the thermal performance of hybrid material-supported n-alkane after a storage time of one year and 50 heating/cooling cycles. The interconnected hybrid material composed of a metal-organic framework (MOF) and graphite improved the shape/thermal stability of tetradecane (TD). The as-synthesized MOF/graphite/TD composites exhibited a high latent heat retention capacity of 84.2%, low leakage rate of 1.25%, and high PCM loading capacity, making them suitable for thermal management applications, such as industrial waste heat recovery systems. Furthermore, the intermolecular interactions and capillary forces between the hybrid materials and TD provided high stability and compatibility. Therefore, the as-prepared hybrid material fabricated in this study can be important in the development of multidirectional composite PCMs with comprehensive thermal characteristics.

Engineering Nano- and Microparticles as Oral Delivery Vehicles to Promote Intestinal Lymphatic Drug Transport

Targeted oral delivery of a drug via the intestinal lymphatic system (ILS) has the advantages of protecting against hepatic first-pass metabolism of the drug and improving its pharmacokinetic performance. It is also a promising route for the oral delivery of vaccines and therapeutic agents to induce mucosal immune responses and treat lymphatic diseases, respectively. This article describes the anatomical structures and physiological characteristics of the ILS, with an emphasis on enterocytes and microfold (M) cells, which are the main gateways for the transport of particulate delivery vehicles across the intestinal epithelium into the lymphatics. A comprehensive overview of recent advances in the rational engineering of particulate vehicles, along with the challenges and opportunities that they present for improving ILS drug delivery, is provided, and the mechanisms by which such vehicles target and transport through enterocytes or M cells are discussed. The use of naturally sourced materials, such as yeast microcapsules and their derived polymeric β-glucans, as novel ILS-targeting delivery vehicles is also reviewed. Such use is the focus of an emerging field of research. Their potential use in the oral delivery of nucleic acids, such as mRNA vaccines, is proposed.