Janus structure hydrogels: recent advances in synthetic strategies, biomedical microstructure and (bio)applications

Janus structure hydrogels (JSHs) are novel materials. Their primary fabrication methods and various applications have been widely reported. JSHs are primarily composed of Janus particles (JNPs) and polysaccharide components. They exhibit two distinct physical or chemical properties, generating intriguing characteristics due to their asymmetric structure. Normally, one side (adhesive interface) is predominantly constituted of polysaccharide components, primarily serving excellent adhesion. On the other side (functional surface), they integrate diverse functionalities, concurrently performing a plethora of synergistic functions. In the biomedical field, JSHs are widely applied in anti-adhesion, drug delivery, wound healing, and other areas. It also exhibits functions in seawater desalination and motion sensing. Thus, JSHs hold broad prospects for applications, and they possess significant research value in nanotechnology, environmental science, healthcare, and other fields. Additionally, this article proposes the challenges and future work facing these fields.

Aggregation induced emission and volatile acid vapour sensing in acridine appended poly (aryl ether) based low molecular weight organogelator

Considerable research attention has been devoted to the development of portable and rapid fluorescence sensors that can selectively detect volatile acids, due to the harmful effects of acid vapour on the environment and human health. Although various types of fluorophores have been reported for sensing volatile acid vapours, regulation of the sensory response using aggregation induced emissive (AIE) based gelators has rarely been reported. In this study, we present the design and synthesis of a novel organogelator that is capable of sensing volatile acids through AIE. An acridine-attached poly(aryl ether) dendron molecular system is synthesized through an aldimine coupling reaction, which self-assembles and forms a gel, exhibiting AIE behavior. The synthesized molecule and prepared gel were characterized using NMR, MASS, XRD, HRSEM and rheology techniques. The AIE property of APD was investigated using steady-state absorption and emission spectroscopic techniques. The sensory response of the APD gelator was tested with various analytes, and the results indicated that APD shows rapid response, particularly to acid vapours, where the detection limits (DL) of trifluoroacetic acid (TFA), hydrochloric acid (HCl) and nitric acid (HNO3) vapor were as low as 0.22, 0.9 and 0.30 ppm, respectively. An APD solid film in filter paper shows a visual color change from yellow to red in an aqueous acidic medium, and the effect is reversed in an alkaline medium. These findings suggest that an APD gelator could potentially be utilized to generate a portable acid vapor sensor kit due to its low detection limit and rapid response time, and it could be also be used as a substitute for existing acid indicators.

Advancements in antimicrobial nanoscale materials and self-assembling systems

Antimicrobial resistance is directly responsible for more deaths per year than either HIV/AIDS or malaria and is predicted to incur a cumulative societal financial burden of at least $100 trillion between 2014 and 2050. Already heralded as one of the greatest threats to human health, the onset of the coronavirus pandemic has accelerated the prevalence of antimicrobial resistant bacterial infections due to factors including increased global antibiotic/antimicrobial use. Thus an urgent need for novel therapeutics to combat what some have termed the 'silent pandemic' is evident. This review acts as a repository of research and an overview of the novel therapeutic strategies being developed to overcome antimicrobial resistance, with a focus on self-assembling systems and nanoscale materials. The fundamental mechanisms of action, as well as the key advantages and disadvantages of each system are discussed, and attention is drawn to key examples within each field. As a result, this review provides a guide to the further design and development of antimicrobial systems, and outlines the interdisciplinary techniques required to translate this fundamental research towards the clinic.

Functional supramolecular gels based on poly(benzyl ether) dendrons and dendrimers

Supramolecular gels, as a fascinating and useful class of soft materials, constructed from low-molecular-weight gelators via noncovalent interactions have attracted increasing attention in the past few decades. Dendrimers and dendrons are highly branched and monodisperse macromolecules with a well-defined three-dimensional architecture and multiple surface functionalities. In recent years, poly(benzyl ether) dendrimers and dendrons are found to be powerful candidates for constructing gel phase materials in organic or aqueous media due to the advantages of capability of forming multiple noncovalent interactions and significant steric impact. In this Feature Article, we provide a comprehensive overview of recent progress in supramolecular gels involving poly(benzyl ether) dendritic molecules. Firstly, we outline the molecular design strategies of dendritic gelators with an emphasis on the discussion of their gelating units and position in molecular structures. Subsequently, we discuss the potential applications of dendritic gels in light harvesting, stimuli responsive materials, sensors and environmental remediation. In addition, the potential challenges and future perspectives of poly(benzyl ether) dendritic gels have also been discussed. It is hoped that this feature article will attract increasing attention and provide some valuable insights for the future design and evolution of supramolecular gels.

Modular amphiphilic poly(aryl ether)-based supramolecular nanomicelles: an efficient endocytic drug carrier

A rationally designed amphiphilic poly(aryl ether)-based dendrimer self-assembles into nanomicelles and exhibits tunable morphology upon varying the hydrophilic chain length. The 30 nm-sized dendrimer nanomicelles successfully entrapped Doxorubicin, demonstrated the sustained release of Doxorubicin and can successfully penetrate cancer cells through caveolae-dependent endocytosis, compared to the free drug.

Cyanide Sensing in Water Using a Copper Metallogel through "Turn-on" Fluorescence

The development of fluorescent probes for selective detection of cyanide has gained considerable attention over the past two decades due to benefits like high selectivity as well as sensitivity, fast response, visual output, accurate quantification, and a simplified sample preparation procedure. However, the propensity of supramolecular gels toward fluorescence sensing of cyanide in aqueous medium is not well explored until now. Herein, we report the design and synthesis of a novel copper based metallogel capable of sensing cyanide in water by fluorescence "turn on". Toward this, a terpyridine attached poly(aryl ether) dendrone derivative (G1) is synthesized which forms gel and exhibits Aggregation Induced Emission (AIE). The addition and diffusion of copper ions to the gel resulted in the formation of a nonluminescent copper metallogel (CuG). The copper metallogel could selectively sense cyanide in water by a fluorescence "turn-on" signal due to the regeneration of the AIE active gel. The mechanistic pathways of the sensing have been studied, and the detection limit for sensing was found to be as low as 1.09 μM. A thin film of CuG was prepared by casting the gel and used as a test strip for the visual detection of cyanide in water.

Vesicles from Amphiphilic Dumbbells and Janus Dendrimers: Bioinspired Self-Assembled Structures for Biomedical Applications

The current review focuses on vesicles obtained from the self-assembly of two types of dendritic macromolecules, namely amphiphilic Janus dendrimers (forming dendrimersomes) and amphiphilic dumbbells. In the first part, we will present some synthetic strategies and the various building blocks that can be used to obtain dendritic-based macromolecules, thereby showing their structural versatility. We put our focus on amphiphilic Janus dendrimers and amphiphilic dumbbells that form vesicles in water but we also encompass vesicles formed thereof in organic solvents. The second part of this review deals with the production methods of these vesicles at the nanoscale but also at the microscale. Furthermore, the influence of various parameters (intrinsic to the amphiphilic JD and extrinsic-from the environment) on the type of vesicle formed will be discussed. In the third part, we will review the numerous biomedical applications of these vesicles of nano- or micron-size.