Stretch‐Induced Drug Delivery from Superhydrophobic Polymer Composites: Use of Crack Propagation Failure Modes for Controlling Release Rates

Advancements in Skin-Mediated Drug Delivery: Mechanisms, Techniques, and Applications

Skin-mediated drug delivery methods currently are receiving significant attention as a promising approach for the enhanced delivery of drugs through the skin. Skin-mediated drug delivery offers the potential to overcome the limitations of traditional drug delivery methods, including oral administration and intravenous injection. The challenges associated with drug permeation through layers of skin, which act as a major barrier, are explored, and strategies to overcome these limitations are discussed in detail. This review categorizes skin-mediated drug delivery methods based on the means of increasing drug permeation, and it provides a comprehensive overview of the mechanisms and techniques associated with these methods. In addition, recent advancements in the application of skin-mediated drug delivery are presented. The review also outlines the limitations of ongoing research and suggests future perspectives of studies regarding the skin-mediated delivery of drugs.

Stimuli-Responsive Electrochemical Energy Storage Devices

Electrochemical energy storage (EES) devices have been swiftly developed in recent years. Stimuli-responsive EES devices that respond to different external stimuli are considered the most advanced EES devices. The stimuli-responsive EES devices enhanced the performance and applications of the EES devices. The capability of the EES devices to respond to the various external stimuli due to produced advanced EES devices that distinguished the best performance and interactions in different situations. The stimuli-responsive EES devices have responsive behavior to different external stimuli including chemical compounds, electricity, photons, mechanical tensions, and temperature. All of these advanced responsiveness behaviors have originated from the functionality and specific structure of the EES devices. The multi-responsive EES devices have been recognized as the next generation of stimuli-responsive EES devices. There are two main steps in developing stimuli-responsive EES devices in the future. The first step is the combination of the economical, environmental, electrochemical, and multi-responsiveness priorities in an EES device. The second step is obtaining some advanced properties such as biocompatibility, flexibility, stretchability, transparency, and wearability in novel stimuli-responsive EES devices. Future studies on stimuli-responsive EES devices will be allocated to merging these significant two steps to improve the performance of the stimuli-responsive EES devices to challenge complicated situations.

Construction and synergistic anticancer efficacy of magnetic targeting cabbage-like Fe3O4@MoS2@ZnO drug carriers

A novel cabbage-like Fe₃O₄@MoS₂@ZnO nanocomposite was successfully fabricated through a facile method. The as-prepared nanocomposite exhibited a saturation magnetization of 45 emu g^-1 as well as possessed a massive pore structure and large surface area, leading to a high DOX loading capacity of 68.14 μg mg^-1; it could effectively deliver drugs to tumor lesion sites under the action of magnetic targeting. The pH-dependent ZnO as a packaging component can block the pores to achieve controlled release of DOX under tumor stimulation conditions (pH 6.5), thereby reducing the side effects of DOX on normal cells and increasing its therapy effects on tumor cells. Moreover, the photothermal conversion efficiency contributed by MoS₂ under 808 nm NIR laser irradiation was utilized to realize effective photothermal therapy (PTT) of cancer, which could be integrated with chemotherapy in a single system. Thus, the resulting Fe₃O₄@MoS₂@ZnO nanocomposites provide hopeful prospects in biomedical applications based on pH sensitivity, magnetic targeting and chemo-photothermal synergistic therapy.

Tension-Activated Delivery of Small Molecules and Proteins from Superhydrophobic Composites

The fabrication and performance of mechanically responsive multilayer superhydrophobic composites are reported. The application of tensile strain triggers the release of small molecules and proteins from these composites, with different tensile strain magnitudes and coating thickness influencing agent release. These mechanoresponsive composites consist of an absorbent drug core surrounded by an electrosprayed superhydrophobic protective coating that limits drug release in the absence of tensile strain. Coating thickness and applied tensile strain control release of chemotherapeutic cisplatin and enzyme β-galactosidase, as measured by atomic absorption and UV-vis spectrophotometry, respectively, with preserved in vitro activity. Such mechanically responsive drug delivery devices, when coupled to existing dynamic mechanical forces in the body or integrated with mechanical medical devices, such as stents, will provide local controlled dosing.

Recent Advances in Wearable Transdermal Delivery Systems

Wearable transdermal delivery systems have recently received tremendous attention due to their noninvasive, convenient, and prolonged administration of pharmacological agents. Here, the material prospects, fabrication processes, and drug-release mechanisms of these types of therapeutic delivery systems are critically reviewed. The latest progress in the development of multifunctional wearable devices capable of closed-loop sensation and drug delivery is also discussed. This survey reveals that wearable transdermal delivery has already made an impact in diverse healthcare applications, while several grand challenges remain.

Bio-Inspired Polymeric Structures with Special Wettability and Their Applications: An Overview

It is not unusual for humans to be inspired by natural phenomena to develop new advanced materials; such materials are called bio-inspired materials. Interest in bio-inspired polymeric superhydrophilic, superhydrophobic, and superoleophobic materials has substantially increased over the last few decades, as has improvement in the related technologies. This review reports the latest developments in bio-inspired polymeric structures with desired wettability that have occurred by mimicking the structures of lotus leaf, rose petals, and the wings and shells of various creatures. The intrinsic role of surface chemistry and structure on delivering superhydrophilicity, superhydrophobicity, and superoleophobicity has been extensively explored. Typical polymers, commonly used structures, and techniques involved in developing bio-inspired surfaces with desired wettability are discussed. Additionally, the latest applications of bio-inspired structures with desired wettability in human activities are also introduced.

Fabrication of Cu–CuO–Fe2O3/Fe anti-sticky and superhydrophobic surfaces on an iron substrate with mechanical abrasion resistance and corrosion resistance

Superhydrophobic Cu–CuO–Fe₂O₃/Fe surfaces with excellent mechanical abrasion resistance and anti-corrosion property were fabricated via immersion and annealing.

Mechanoresponsive materials for drug delivery: Harnessing forces for controlled release

Mechanically-activated delivery systems harness existing physiological and/or externally-applied forces to provide spatiotemporal control over the release of active agents. Current strategies to deliver therapeutic proteins and drugs use three types of mechanical stimuli: compression, tension, and shear. Based on the intended application, each stimulus requires specific material selection, in terms of substrate composition and size (e.g., macrostructured materials and nanomaterials), for optimal in vitro and in vivo performance. For example, compressive systems typically utilize hydrogels or elastomeric substrates that respond to and withstand cyclic compressive loading, whereas, tension-responsive systems use composites to compartmentalize payloads. Finally, shear-activated systems are based on nanoassemblies or microaggregates that respond to physiological or externally-applied shear stresses. In order to provide a comprehensive assessment of current research on mechanoresponsive drug delivery, the mechanical stimuli intrinsically present in the human body are first discussed, along with the mechanical forces typically applied during medical device interventions, followed by in-depth descriptions of compression, tension, and shear-mediated drug delivery devices. We conclude by summarizing the progress of current research aimed at integrating mechanoresponsive elements within these devices, identifying additional clinical opportunities for mechanically-activated systems, and discussing future prospects.

Spontaneous exfoliation of a drying gel

Wet starch cracks when it dries inhomogeneously, while hot glass cracks when it cools non-uniformly. In both cases, differential shrinkage induced by drying/cooling from the surface causes superficial cracks to grow perpendicular to the surface in different patterns. In contrast with these observations of bulk cracking in brittle materials, when a soft and homogeneously swollen polymer gel dries, differential strains lead to the peeling of a thin layer that spontaneously tears away from the bulk. Continued drying leads to the process repeating itself, forming a peeled-layered structure. The emergent thickness of the exfoliated layer is a function of both the geometry of the original gel and the physical parameters associated with the drying rate and external temperature. We characterize the experimental conditions under which layer peeling can arise, and use simulations to corroborate these observations. Finally, a minimal theory explains the scaling of the peel thickness, consistent with our experiments.