AIE/AEE tripodal PEGyl-melphalan supramolecules and detection of trinitrophenol in water

Herein, the design of a novel aggregation-induced emission (AIE) supramolecular fluorescence sensor (TA-PEGn) based on a tridentate melphalan derivative and three different molecular weight PEGs is presented. The three TA-PEGn sensors could self-assemble into a supramolecular system in water and show sensitive and selective responses toward trinitrophenol.

Smart G-quadruplex hydrogels: From preparations to comprehensive applications

In recent years, the accelerated development of G-quadruplexes and hydrogels has driven the development of intelligent biomaterials. Based on the excellent biocompatibility and special biological functions of G-quadruplexes, and the hydrophilicity, high-water retention, high water content, flexibility and excellent biodegradability of hydrogels, G-quadruplex hydrogels are widely used in various fields by combining the dual advantages of G-quadruplexes and hydrogels. Here, we provide a systematic and comprehensive classification of G-quadruplex hydrogels in terms of preparation strategies and applications. This paper reveals how G-quadruplex hydrogels skillfully utilize the special biological functions of G-quadruplexes and the skeleton structure of hydrogels, and expounds its applications in the fields of biomedicine, biocatalysis, biosensing and biomaterials. In addition, we deeply analyze the challenges in preparation, applications, stability and safety of G-quadruplex hydrogels, as well as potential future development directions.

Advanced Binary Guanosine and Guanosine 5'-Monophosphate Cell-Laden Hydrogels for Soft Tissue Reconstruction by 3D Bioprinting

Soft tissue defects or pathologies frequently necessitate the use of biomaterials that provide the volume required for subsequent vascularization and tissue formation as autrografts are not always a feasible alternative. Supramolecular hydrogels represent promising candidates because of their 3D structure, which resembles the native extracellular matrix, and their capacity to entrap and sustain living cells. Guanosine-based hydrogels have emerged as prime candidates in recent years since the nucleoside self-assembles into well-ordered structures like G-quadruplexes by coordinating K⁺ ions and π-π stacking, ultimately forming an extensive nanofibrillar network. However, such compositions were frequently inappropriate for 3D printing due to material spreading and low shape stability over time. Thus, the present work aimed to develop a binary cell-laden hydrogel capable of ensuring cell survival while providing enough stability to ensure scaffold biointegration during soft tissue reconstruction. For that purpose, a binary hydrogel made of guanosine and guanosine 5'-monophosphate was optimized, rat mesenchymal stem cells were entrapped, and the composition was bioprinted. To further increase stability, the printed structure was coated with hyperbranched polyethylenimine. Scanning electron microscopic studies demonstrated an extensive nanofibrillar network, indicating excellent G-quadruplex formation, and rheological analysis confirmed good printing and thixotropic qualities. Additionally, diffusion tests using fluorescein isothiocyanate labeled-dextran (70, 500, and 2000 kDa) showed that nutrients of various molecular weights may diffuse through the hydrogel scaffold. Finally, cells were evenly distributed throughout the printed scaffold, cell survival was 85% after 21 days, and lipid droplet formation was observed after 7 days under adipogenic conditions, indicating successful differentiation and proper cell functioning. To conclude, such hydrogels may enable the 3D bioprinting of customized scaffolds perfectly matching the respective soft tissue defect, thereby potentially improving the outcome of the tissue reconstruction intervention.

Guanine Analogue-Based Assemblies: Construction and Luminescence Functions

As one of the natural nucleobases, guanine has attracted increasing interest in molecular self-assembly science because of its abundant interaction sites and high electron cloud density. Guanines, guanine derivatives, and guanine-rich DNA sequence are able to self-assemble into versatile aggregate structures by the means of hydrogen bonds and π-π, ion-dipole, solvophobic, and electrostatic interactions. Recent advances have shown that many guanine analogue-based (G-based) luminescent aggregates exhibit promising applications for fluorescent and chemiluminescent sensing and circularly polarized luminescence (CPL). This perspective summarizes the state-of-art strategies for constructing G-based assemblies and presents representative examples for luminescence functions. Finally, the inspirations are provided for exploiting unique G-based systems and luminescent G-based assemblies.

Hybrid DNA-Carbon Dot-Poly(vinylpyrrolidone) Hydrogel with Self-Healing and Shape Memory Properties for Simultaneous Trackable Drug Delivery and Visible-Light-Induced Antimicrobial Photodynamic Inactivation

A two-step methodology for simultaneous conjugation of DNA and poly(vinylpyrrolidone) (PVP) polymer to a single carbon quantum dot (CD) is demonstrated for the first time to fabricate a pH-responsive DNA-CD-PVP hybrid hydrogel. Cross-linking in the hydrogel was achieved using CD as the common nucleus through the formation of DNA I-motif conformation at neutral to acidic pH and noncovalent interaction of PVP that infuse self-healing and shape memory properties in the hydrogel. The hydrogel is capable of loading and sustained delivery of drugs for more than 2 weeks as demonstrated using a model drug, Hemin. The quenching of fluorescence of CD by Hemin was trackable even through simple visual monitoring, which showed that Hemin can diffuse from the loaded part to the unloaded part of the hydrogel during the self-healing process. Most significantly, the chosen CD generates reactive oxygen species (ROS) upon visible light irradiation, armoring the hydrogel with worthy antimicrobial activity. Biocompatibility of the DNA-CD-PVP hydrogel was established on human fibroblast cells, indicating their potential use in biomedical area pertaining to wound healing.