Switching the Mode of Drug Release from a Reaction-Coupled Low-Molecular-Weight Gelator System by Altering Its Reaction Pathway

Hydrogels as drug delivery platforms for orthopedic diseases treatment: A review

The skeletal system serves as a crucial support structure for the human body, any damage or disease to bones can result in prolonged pain, impaired mobility, and other negative outcomes. For the treatment of bone diseases, with the in-depth study of the therapeutic mechanism, various small molecule drugs, cells, cytokines, growth factors, bioactive ions, collectively referred to as "drugs" in this context, are increasingly investigated for their potential application in surgical procedures, defect repair, or treatment of diseased bone regions. However, various challenges, including, low stability, the necessity for precise dosage control, are encountered in the administration of drugs. Consequently, the advancement of drug delivery platforms is crucial to safeguard drug efficacy and address the requirement for dosage regulation. Given the attributes of current drug delivery platforms, hydrogels exhibit favorable biocompatibility and offer the ability to easily regulate drug loading and release. As a carrier with diverse properties, abundant varieties, optimal performance, hydrogels present a promising solution in drug delivery. This paper aims to analyze the potential of hydrogel as a delivery platform for treating orthopedics diseases by reviewing the characteristics of hydrogel delivery systems, mechanisms of drug binding, current research findings, and projecting future developments in this field.

Photo-responsive organogelator based on cholesterol incorporated sugar-azobenzene derivatives

In this report, the design and synthesis of cholesterol-based sugar azobenzene derivatives as photo-responsive organogelators have been carried out. The gel formation in different solvents was examined, and a minimum CGC of 0.5 % (w/v) was attained in toluene. The mechanism of self-assembly of organogels was characterized by using 1H NMR, UV-Vis, FT-IR, and PXRD. These organogelators show photo-isomerization and photo-reversible properties, which were studied using absorption spectra. Computational studies studied the optimized dimer structures and geometries of the trans and cis isomers. The prominent nature of this designed structure makes it an outstanding, intelligent soft material with plausible applications.

G4-Hemin-loaded 2D nanosheets for combined and targeted chemo-photodynamic cancer therapy

Synergetic combination therapy is emerging as one of the most promising approaches for cancer treatment. Among the various therapeutic approaches, PDT has received particular attention due to its non-invasive nature. However, the therapeutic performance of PDT is severely affected by tumour hypoxia. Herein, we report a supramolecular strategy for the fabrication of a PDT-active 2D nanosheet loaded with a POD mimicking DNAzyme for the synergetic combination of PDT and CDT for targeted cancer therapy. Assembly of biotin-functionalized BODIPY (1) and cationic β-cyclodextrin (β-CD+) leads to the formation of a 1/β-CD+ nanosheet with positively charged β-CD+ on the surface of the sheet. The cationic face of the 1/β-CD+ sheet was then loaded with a POD-mimicking Hem-loaded G-quadruplex aptamer (Hem/DNA1) via electrostatic interactions (1/β-CD+/Hem/DNA1). Cellular internalization of the 1/β-CD+/Hem/DNA1 nanosheet occurs via a receptor-mediated endocytic pathway, which then undergoes lysosomal escape. Subsequently, Hem/DNA1 on the surface of 1/β-CD+/Hem/DNA1 reacts with endogenous H2O2via the Fenton pathway to produce ˙OH and O2. Moreover, under cellular conditions, Hem inside the 1/β-CD+/Hem/DNA1 nanosheet produces Fe2+, which then undergoes another Fenton reaction to produce ˙OH and O2. The Fe3+ generated after the Fenton reaction is then reduced in situ to Fe2+ by glutathione for the next Fenton cycle. At the same time, photoirradiation of the 1/β-CD+ nanosheet using a 635 nm laser produces 1O2via the PDT pathway by using endogenous O2. The most remarkable feature of the present nanoformulation is the cooperativity in its therapeutic action, wherein O2 produced during the CDT pathway was used by the 1/β-CD+ sheet for improving its PDT efficacy in the hypoxic tumor microenvironment. This work represents a unique combination of CDT and PDT for targeted cancer therapy, wherein the CDT action of the nanoagent enhances the PDT efficacy and we strongly believe that this approach would encourage researchers to design similar combination therapy for advancements in the treatment of cancer.

Fluoride-Ion-Responsive Sol-Gel Transition in an L-Cysteine/AgNO3 System: Self-Assembly Peculiarities and Anticancer Activity

Supramolecular hydrogels based on low-molecular-weight compounds are a unique class of so-called "soft" materials, formed by weak non-covalent interactions between precursors at their millimolar concentrations. Due to the variety of structures that can be formed using different low-molecular-weight gelators, they are widely used in various fields of technology and medicine. In this study, we report for the first time an unusual self-assembly process of mixing a hydrosol obtained from L-cysteine and silver nitrate (cysteine-silver sol-CSS) with sodium halides. Modern instrumental techniques such as viscosimetry, UV spectroscopy, dynamic light scattering, zeta potential measurements, SEM and EDS identified that adding fluoride anions to CSS is able to form stable hydrogels of a thixotropic nature, while Cl-, Br- and I- lead to precipitation. The self-assembly process proceeds using a narrow concentration range of F-. An increase in the fluoride anion content in the system leads to a change in the gel network morphology from elongated structures to spherical ones. This fact is reflected in a decrease in the gel viscosity and a number of gel-sol-gel transition cycles. The mechanism of F-'s interaction with hydrosol includes the condensation of anions on the positive surface of the CSS nanoparticles, their binding via electrostatic forces and the formation of a resulting gel carcass. In vitro analysis showed that the hydrogels suppressed human squamous carcinoma cells at a micromolar sample concentration. The obtained soft gels could have potential applications against cutaneous malignancy and as carriers for fluoride anion and other bioactive substance delivery.

Development of Low-Molecular-Weight Gelator/Polymer Composite Materials Utilizing the Gelation and Swelling Process of Polymeric Materials

The creation of polymer composite materials by compositing fillers into polymer materials is an effective method of improving the properties of polymer materials, and the development of new fillers and their novel composite methods is expected to lead to the creation of new polymer composite materials. In this study, we develop a new filler material made of low-molecular-weight gelators by applying a gelation process that simultaneously performs the swelling (gelation) of crosslinked polymer materials and the self-assembly of low-molecular-weight gelators into low-dimensional crystals in organic solvents within polymer materials. The gelation process of crosslinking rubber-based polymers using alkylhydrazides/toluene as the low-molecular-weight gelator allowed us to composite self-assembled sheet-like crystals of alkylhydrazides as fillers in polymeric materials, as suggested by various microscopic observations, including infrared absorption measurements, small-angle X-ray diffraction measurements and thermal analysis, microscopy, and infrared absorption measurements. Furthermore, tensile tests of the composite materials demonstrated that the presence of fillers improved both the Young's modulus and the tensile strength, as well as the elongation at yield. Additionally, heat treatment was shown to facilitate filler dispersion and enhance the mechanical properties. The findings demonstrate the potential of self-assembled sheet-like crystals of low-molecular-weight gelators as novel filler materials for polymers. The study's composite method utilizing gelators via gelation proved effective.

Supramolecular gels - a panorama of low-molecular-weight gelators from ancient origins to next-generation technologies

Supramolecular gels, self-assembled from low-molecular-weight gelators (LMWGs), have a long history and a bright future. This review provides an overview of these materials, from their use in lubrication and personal care in the ancient world, through to next-generation technologies. In academic terms, colloid scientists in the 19th and early 20th centuries first understood such gels as being physically assembled as a result of weak interactions, combining a solid-like network having a degree of crystalline order with a highly mobile liquid-like phase. During the 20th century, industrial scientists began using these materials in new applications in the polymer, oil and food industries. The advent of supramolecular chemistry in the late 20th century, with its focus on non-covalent interactions and controlled self-assembly, saw the horizons for these materials shifted significantly beyond their historic rheological applications, expanding their potential. The ability to tune the LMWG chemical structure, manipulate hierarchical assembly, develop multi-component systems, and introduce new types of responsive and interactive behaviour, has been transformative. Furthermore, the dynamics of these materials are increasingly understood, creating metastable gels and transiently-fueled systems. New approaches to shaping and patterning gels are providing a unique opportunity for more sophisticated uses. These supramolecular advances are increasingly underpinning and informing next-generation applications - from drug delivery and regenerative medicine to environmental remediation and sustainable energy. In summary, this article presents a panorama over the field of supramolecular gels, emphasising how both academic and industrial scientists are building on the past, and engaging new fundamental insights and innovative concepts to open up exciting horizons for their future use.

Concentration- and Solvent-Induced Chiral Tuning by Manipulating Non-Proteinogenic Amino Acids in Glycoconjugate Supra-Scaffolds: Interaction with Protein, and Streptomycin Delivery

We showed solvent- and concentration-triggered chiral tuning of the fibrous assemblies of two novel glycoconjugates Z-P(Gly)-Glu and Z-F(4-N)-Glu made by chemical attachment of Cbz-protected [short as Z)] non-proteinogenic amino acids L-phenylglycine [short as P(Gly)] and 4-Nitro-L-phenylalanine [short as F(4-N)] with D-glucosamine [short as Glu]. Both biomimetic gelators can form self-healing and shape-persistent gels with a very low critical gelator concentration in water as well as in various organic solvents, indicating they are ambidextrous supergelators. Detailed spectroscopic studies suggested β-sheet secondary structure formation during anisotropic self-aggregation of the gelators which resulted in the formation of hierarchical left-handed helical fibers in acetone with an interlayer spacing of 2.4 nm. After the physical characterization of the gels, serum protein interaction with the gelators was assessed, indicating they may be ideal for biomedical applications. Further, both gelators are benign, non-immunogenic, non-allergenic, and non-toxic in nature, which was confirmed by performing the blood parameters and liver function tests on Wister rats. Streptomycin-loaded hydrogels showed efficacious antibacterial activity in vitro and in vivo as well. Finally, cell attachment and biocompatibility of the hydrogels were demonstrated which opens a newer avenue for promising biomedical and therapeutic applications.

Development of Gelled-Oil Nanoparticles for the Encapsulation and Release of Berberine

In this study, a new drug carrier based on gelled-oil nanoparticles (GNPs) was designed and synthesized for the encapsulation and release of the model hydrophobic drug, berberine chloride (BCl). Two compositions with different oil phases were examined, sesame oil (SO) and cinnamaldehyde (Cin), which were emulsified with water, stabilized with Tween 80 (Tw80), and gelled using an N-alkylated primary oxalamide low-molecular-weight gelator (LMWG) to give stable dispersions of GNPs between 100 and 200 nm in size. The GNP formulation with Cin was significantly favored over SO due to (1) lower gel melting temperatures, (2) higher gel mechanical strength, and (3) significantly higher solubility, encapsulation efficiency, and loading of BCl. Also, the solubility and loading of BCl in Cin were significantly increased (at least 7-fold) with the addition of cinnamic acid. In vitro release studies showed that the release of BCl from the GNPs was independent of gelator concentration and lower than that for BCl solution and the corresponding nanoemulsion (no LWMG). Also, cell internalization studies suggested that the N-alkylated primary oxalamide LMWG did not interfere with the internalization efficiency of BCl into mouse mast cells. Altogether, this work demonstrates the potential use of these new GNP formulations for biomedical studies involving the encapsulation of drugs and nutraceuticals and their controlled release.