Dynamics in Controllable Stimuli-Responsive Self-Assembly of Polymer Vesicles with Stable Radical Functionality

In Vitro and In Live-Cell Rapid Hydrazine Detection by Disaggregation of the AIEgen Microstructure

In this study, efficient hydrazine detectors are developed using disaggregation of AIEgen microstructures. A new class of 2,4,6-triphenylaniline-based AIEgens are designed to alter the optoelectronic properties in different aggregated states. These 2,4,6-triphenylaniline-based molecules (SB1, SB2, and SB3) are self-assembled in the aqueous medium as well as in physiological condition, creating distinct microdomains and effectively showing tunable aggregation- induced emission (AIE) properties. The aggregation behavior was extensively investigated using advanced spectroscopic and microscopic techniques, by modulating the water content in acetonitrile solution. The aggregated state of SB3 emerged as the most sensitive hydrazine detector, achieving an exceptional detection limit of 0.054 µM, outperforming compounds SB1 (2.8 µM) and SB2 (2.2 µM). This attributed to hydrogen bond induced disaggregation of AIEgen aggregates, resulting in a pronounced turn-on fluorescence response by intramolecular charge transfer (ICT). Not only aqueous hydrazine or hydrazine vapor detection, but also the SB3 permeate cell membrane, localize in the perinuclear area, and detect intracellular hydrazine with great specificity. This on-site and real-time fluorogenic hydrazine detection have prospective applications in monitoring the environment and biomedical imaging.

Macroscopic Structural Transition of Nickel Dithiolate Capsule with Uniaxial Magnetic Anisotropy in Water

Meeting the Internet of Things (IoT) demand for flexible organic spintronics requires dynamically flexible, "soft" organic magnetic materials. These materials should be capable of reordering their macroscopic assemblies in response to external stimuli. Unlike conventional rigid, "hard" crystalline organic paramagnets, that are typically composed of open-shell π- or d/π-conjugated planar molecules and rely on intermolecular interactions in the ordered, assembled structures, soft paramagnets necessitate a delicate balance between long-range structural order (essential for controlling magnetic properties) and dynamic flexibility a challenge previously unmet for open-shell planar molecules. In this study, an amphiphilic d/π-conjugated nickel dithiolate radical anion salt is presented that self-assembles into ordered membranes, forming capsule-like macrostructures with exceptional stability in aqueous environments. This design achieves the desired balance. These assemblies exhibit uniaxial magnetic anisotropy driven by significant spin-spin interactions and undergo temperature-dependent macroscopic structural transitions representing, to the knowledge, the first observation of such behavior for assemblies of open-shell planar molecules. This well-defined, single-molecular-weight system provides critical structural and mechanism insights for soft matter design and a versatile platform for spintronic applications. The findings advance the development of flexible, tunable molecular soft paramagnets, expanding their potential for innovative applications in flexible devices and beyond.

Biomass-Derived Organonanomaterials as Contrast Agents for Efficient Magnetic Resonance Imaging

Magnetic resonance imaging (MRI) is a popular imaging tool that is valuable for the early detection and monitoring of malignancies because it does not involve radiation and is noninvasive. Metal-based contrast agents (CAs) are commonly used in clinical settings despite concerns about the toxicity of free metals. Therefore, finding alternative nontoxic imaging probes is vital. In this work, we have synthesized and effectively utilized sustainable biomass lignin-based all-organic nanoconjugates linked with nitroxide radicals as MRI CAs. Lignin grafted with poly(4-glycidyloxy-2,2,6,6-tetramethylpiperidine-1-oxyl) (LPGT) exhibits a longitudinal relaxivity of 0.54 mM-1 s-1. LPGT shows exceptional characteristics, including resistance to reduction and nontoxicity toward living organisms. LPGT displays enhanced MRI contrast in the BALB/c mouse model for a duration exceeding 4.35 h. Our primary goal is to design MRI agents that are exceptionally effective sustainable biomass-derived materials and do not require the use of metals. Nicely, LPGT offers adequate contrast enhancement at 5-fold lower (0.020 mmol/kg) than the standard dose (0.1 mmol/kg), easing worries about toxic metal buildup. Consequently, LPGT shows promise as a feasible CA for metal-free MRI.

Co-assembly of Amphiphilic Triblock Copolymers with Nanodrugs and Drug Release Kinetics in Solution

Polymeric vesicles present great potential in disease treatment as they can be featured as a structurally stable and easily functionalized drug carrier that can simultaneously encapsulate multiple drugs and release them on-demand. Based on the dissipative particle dynamics (DPD) simulation, the drug-loaded vesicles were designed by the co-assembly process of linear amphiphilic triblock copolymers and hydrophobic nanodrugs in solvents, and most importantly, the drug release behavior of drug-loaded vesicles were intensively investigated. The drug-loaded aggregates, such as vesicles, spherical micelles, and disk-like micelles, were observed by varying the size and concentration of nanodrugs and the length of the hydrophobic block. The distribution of nanodrugs in the vesicles was intensively analyzed. As the size of the nanodrugs increases, the localization of nanodrugs change from being unable to fully wrap in the vesicle wall to the uniform distribution and finally to the aggregation in the vesicles at the fixed concentration of nanodrugs. The membrane thickness of the drug-loaded polymeric vesicle can be increased, and the nanodrugs localized closer to the center of the vesicle by increasing the length of the hydrophobic block. The nanodrugs will be released from vesicles by varying the interactions between the nanodrug and the solvent or the hydrophobic block and the solvent, respectively. We found that the release kinetics conforms to the first-order kinetic model, which can be used to fit the cumulative release rate of nanodrugs over time. The results showed that increasing the size of nanodrugs, the length of hydrophobic block, and the interaction parameters between the hydrophobic block and the solvent will slow down the release rate of the nanodrug and change the drug release process from monophasic to biphasic release model.

In situ stimulus-responsive self-assembled nanomaterials for drug delivery and disease treatment

The individual motifs that respond to specific stimuli for the self-assembly of nanomaterials play important roles. In situ constructed nanomaterials are formed spontaneously without human intervention and have promising applications in bioscience. However, due to the complex physiological environment of the human body, designing stimulus-responsive self-assembled nanomaterials in vivo is a challenging problem for researchers. In this article, we discuss the self-assembly principles of various nanomaterials in response to the tissue microenvironment, cell membrane, and intracellular stimuli. We propose the applications and advantages of in situ self-assembly in drug delivery and disease diagnosis and treatment, with a focus on in situ self-assembly at the lesion site, especially in cancer. Additionally, we introduce the significance of introducing exogenous stimulation to construct self-assembly in vivo. Based on this foundation, we put forward the prospects and possible challenges in the field of in situ self-assembly. This review uncovers the relationship between the structure and properties of in situ self-assembled nanomaterials and provides new ideas for innovative drug molecular design and development to solve the problems in the targeted delivery and precision medicine.