Design and Self-Assembly of Sugar-Based Amphiphiles: Spherical to Cylindrical Micelles

Analysis of carbohydrates and glycoconjugates by matrix-assisted laser desorption/ionization mass spectrometry: An update for 2021-2022

The use of matrix-assisted laser desorption/ionization (MALDI) mass spectrometry for the analysis of carbohydrates and glycoconjugates is a well-established technique and this review is the 12th update of the original article published in 1999 and brings coverage of the literature to the end of 2022. As with previous review, this review also includes a few papers that describe methods appropriate to analysis by MALDI, such as sample preparation, even though the ionization method is not MALDI. The review follows the same format as previous reviews. It is divided into three sections: (1) general aspects such as theory of the MALDI process, matrices, derivatization, MALDI imaging, fragmentation, quantification and the use of computer software for structural identification. (2) Applications to various structural types such as oligo- and polysaccharides, glycoproteins, glycolipids, glycosides and biopharmaceuticals, and (3) other general areas such as medicine, industrial processes, natural products and glycan synthesis where MALDI is extensively used. Much of the material relating to applications is presented in tabular form. MALDI is still an ideal technique for carbohydrate analysis, particularly in its ability to produce single ions from each analyte and advancements in the technique and range of applications show little sign of diminishing.

Chiral Self-Assembly of Biphenyl-Cored Carbohydrate Bolaamphiphiles and Molecular Dynamic Simulation-Derived Mechanistic Insights

The presence of multiple chiral centers and constitutions in carbohydrates opens up a facile access to uncover supramolecular chirality properties in self-assembled carbohydrate bolaamphiphiles. In this work, bolaamphiphiles are presented that present monosaccharide moieties at the termini of an internal p,p'-biphenyl core segment. The core segment exhibits a planar twisting, which promotes chiral self-assembly of the bolaamphiphiles. α-D-Mannopyranoside-biphenyl-mannopyranoside bolaamphiphile self-assembles with a helicity, whereas α-L-rhamnopyranoside-biphenyl-rhamnopyranoside inverts this helicity in aq. solutions. The propensity for the emerging supramolecular chirality depends on the pH of the solution, where alkaline pH retains the helicity, whereas acidic pH abolishes the same. The concentration dependence of the chiral self-assembly properties is evaluated in solution. Molecular dynamics (MD) simulation studies reveal the thermodynamic states and interactions crucial for the self-assembly of biphenyl and the correlated terphenyl bolaamphiphiles. Morphological studies by microscopies ascertain the helicities in the solid state. The multivalent presentation of α-D-mannopyranoside in the self-assembled structures permits complexation with a relevant lectin, as assessed by turbidity assays. Cytotoxicity assessments of biphenyl bolaamphiphiles on the MCF-7 cell line reveal that the α-L-rhamnopyranoside bolaamphiphile has an IC50 of 89.6 ± 3.3 µm, indicating higher toxicity compared to the α-D-mannopyranoside bolaamphiphile, which has an IC50 greater than 100 µm.

Self-assembly of malto-oligosaccharide-block-solanesol in aqueous solutions: Investigating morphology and sugar-based physiological compatibility

Starch-derived hydrophilic malto-oligosaccharides (Glcn, where n = 1-7) conjugated to hydrophobic solanesol through click chemistry, i.e., Glcn-b-Sol copolymers, have demonstrated significant promise in developing fully natural block co-oligomers for solid-state nanopatterning applications. This study explores in detail the solution self-assembly, lectin recognition, and pancreatic digestion of Glc6- and Glc7-b-Sol. Above a critical micelle concentration (CMC) of 0.3 g/L, both systems demonstrated self-assembly into diverse morphologies. Using the pyrene probe method, a polarity parameter of 1.2 was observed at 1 mM samples. Dynamic light scattering experiments, which measured autocorrelation functions and relaxation times at various angles, revealed the anisotropic and heterogeneous characteristics of the morphologies. Specifically, Glc6-b-Sol predominantly exhibited spherical and elongated worm-like micelles with considerable heterogeneity across the entire range of concentrations studied. In contrast, Glc7-b-Sol primarily formed stable, shorter, worm-like structures at lower concentrations, as observed by transmission electron microscopy. However, small-angle X-ray scattering showed that higher concentrations led to the formation of longer worm-like structures, with Glc7-b-Sol forming thicker diameters. Notably, interaction with Concanavalin A above the CMC resulted in complete agglutination. Pancreatic digestion with hog pancreas α-amylase resulted in morphological alterations, with Glc3- and Glc4-b-Sol emerging as the primary digestion products for Glc6- and Glc7-b-Sol, respectively.

Fully biosourced amphiphilic block copolymer from tamarind seed xyloglucan and solanesol: synthesis, aqueous self-assembly, and drug encapsulation

This study aims to explore the development of natural bio-based amphiphilic block copolymers for drug delivery applications. We investigated block copolymers derived from tamarind seed xyloglucan and solanesol, focusing on their synthesis, structural analysis, aqueous self-assembly, and drug encapsulation. Specifically, xyloglucan hydrolysate segments with number-average degrees of polymerization (DPs) of between 8 and 44 (XOS8, XMS10, XMS16, XMS28, and XMS44) were used as the hydrophilic blocks, whereas plant-sourced solanesol was selected as the hydrophobic segment. These two segments were linked via click chemistry to create novel XOS-b-Sol and XMS-b-Sol copolymers, where XOS refers to a xyloglucan oligosaccharide (DP < 10), and XMS denotes a megalosaccharide, defined as a larger xyloglucan polymer with a DP >10. XMS10- and XMS16-b-Sol self-assembled in aqueous media to form predominantly narrowly dispersed spherical micelles, while XOS8-b-Sol exhibited a combination of short wormlike structures and spherical micelles. Small-angle X-ray scattering, multi-angle dynamic light scattering, and transmission electron microscopy revealed the XMS28- and XMS44-b-Sol micelles are morphologically diverse. XMS10-b-Sol solubilized quercetin, a water-insoluble flavonoid, highly effectively, highlighting its potential as an environmentally benign drug carrier.

Natural Products from Herbal Medicine Self-Assemble into Advanced Bioactive Materials

Novel biomaterials are becoming more crucial in treating human diseases. However, many materials require complex artificial modifications and synthesis, leading to potential difficulties in preparation, side effects, and clinical translation. Recently, significant progress has been achieved in terms of direct self-assembly of natural products from herbal medicine (NPHM), an important source for novel medications, resulting in a wide range of bioactive supramolecular materials including gels, and nanoparticles. The NPHM-based supramolecular bioactive materials are produced from renewable resources, are simple to prepare, and have demonstrated multi-functionality including slow-release, smart-responsive release, and especially possess powerful biological effects to treat various diseases. In this review, NPHM-based supramolecular bioactive materials have been revealed as an emerging, revolutionary, and promising strategy. The development, advantages, and limitations of NPHM, as well as the advantageous position of NPHM-based materials, are first reviewed. Subsequently, a systematic and comprehensive analysis of the self-assembly strategies specific to seven major classes of NPHM is highlighted. Insights into the influence of NPHM structural features on the formation of supramolecular materials are also provided. Finally, the drivers and preparations are summarized, emphasizing the biomedical applications, future scientific challenges, and opportunities, with the hope of igniting inspiration for future research and applications.

Amphiphilic Low-Molecular-Weight Gelators Bearing β-S-N-Acetylglucosamine Linked to a Tartaric Acid Scaffold: Synthesis, Self-Assembly and Wheat Germ Agglutinin Binding

The self-assembly of carbohydrate-based amphiphiles can lead to colloidal soft materials such as supramolecular gels featuring highly desirable characteristics like biodegradability and biocompatibility. The report herein presents the synthesis, characterization and supramolecular self-assembly, physical gelation and wheat lectin binding of two structurally related amphiphilic compounds having β-S-N-acetylglucosamine residues linked to a 2,3-diacyl-N,N'-dipropargylated-l-tartaric diamide. A 1-thio-β-N-acetyl-d-glucosamine precursor attached to a conveniently functionalized linker with an azido group was synthesized by means of a one-pot procedure followed by deprotection. A click reaction successfully led to the two amphiphiles, which differed in length of the fatty acid attached to the tartaric acid scaffold. Although both compounds are poorly soluble in water and organic solvents, the difference in terms of hydrophilic moieties provided them with distinct supramolecular gelation properties. While the presence of an octadecyl chain produced a hydrogelator, the dodecadecyl homologue would only form weak gels in DMSO. SEM and rheology experiments confirmed the characteristic fibrillar morphology and viscoelastic properties, in agreement with the presence of physical gels. Both amphiphiles were able to interact reversibly with wheat germ agglutinin (WGA), a lectin that specifically recognizes GlcNAc residues, indicating a potential use in the food industry, as a gluten sensitivity manager, as well as in health-related industries, for example, for drug delivery systems.

Research Status of Dendrimer Micelles in Tumor Therapy for Drug Delivery

Dendrimers are a family of polymers with highly branched structure, well-defined composition, and extensive functional groups, which have attracted great attention in biomedical applications. Micelles formed by dendrimers are ideal nanocarriers for delivering anticancer agents due to the explicit study of their characteristics of particle size, charge, and biological properties such as toxicity, blood circulation time, biodistribution, and cellular internalization. Here, the classification, preparation, and structure of dendrimer micelles are reviewed, and the specific functional groups modified on the surface of dendrimers for tumor active targeting, stimuli-responsive drug release, reduced toxicity, and prolonged blood circulation time are discussed. In addition, their applications are summarized as various platforms for biomedical applications related to cancer therapy including drug delivery, gene transfection, nano-contrast for imaging, and combined therapy. Other applications such as tissue engineering and biosensor are also involved. Finally, the possible challenges and perspectives of dendrimer micelles for their further applications are discussed.

Unusual Increasing Viscoelasticity of Wormlike Micelles Composed of Imidazolium Gemini Surfactants with Temperature

The viscoelasticity of wormlike micelles composed of ionic surfactants typically shows an exponential decrease with increasing temperature, which limits their application in relatively high-temperature (>90.0 °C) oilfields and the synthesis of functional materials as supramolecular templates at high temperatures. In this work, a series of imidazolium gemini surfactants, 1,9-(ethane-1,2-diyl)bis(3-alkyl-1H-imidazol-3-ium) bromide ([C_n-2-C_nim]Br₂, n = 12, 14, 16, 18, 20), were synthesized. Their surface activities and aggregation behaviors in water were studied by electrical conductivity, rheology, polarization optical microscopy, small-angle X-ray scattering, ζ potential, and hydrogen nuclear magnetic resonance measurements. [C₁₂-2-C₁₂im]Br₂ and [C₁₄-2-C₁₄im]Br₂ mainly precipitate in water. [C_n-2-C_nim]Br₂ (n = 16, 18, 20) forms lamellar liquid crystals over a large range of concentrations at low temperatures. With the increase of temperature, the lamellar liquid crystals transit to wormlike micelles. Interestingly, the viscoelasticity of the three wormlike micelles first increases to the maximum and then decreases with increasing temperature. These wormlike micelles without additives retain high viscoelasticity up to 90.0 °C or above. With the increase of the alkyl chain length of the surfactants, the transition temperature of lamellar liquid crystal to wormlike micelles and the disintegration temperature of wormlike micelles increase. The unusual increase of the viscoelasticity of wormlike micelles was due to the desorption of weakly bound counterions and the extension of the long hydrophobic chains of surfactants at high temperatures.

Tuning the Chiral Structures from Self-Assembled Carbohydrate Derivatives

Carbohydrates have been regarded as one of the most ideally suited candidates for chirality study via self-assembly owning to their unique chemical structures, abundance, and sustainability. Much efforts have been devoted to design and synthesize diverse carbohydrate derivatives and self-assemble them into various supermolecular morphologies. Nevertheless, still inadequate attention is paid to deeply and comprehensively understand how the carbohydrate structures and self-assembly approaches affect the final morphologies and properties for future demands. Herein, to fulfill the need, a range of recently published studies relating to the chirality of carbohydrates is reviewed and discussed. Furthermore, to tune the chirality of carbohydrate-based structures on both molecular and superstructural levels via chirality transfer and chirality expression, the designing of the molecules and choosing of the proper approaches for self-assembly are elucidated.

Mannose-based surfactant as biofunctional nanoemulsion stabilizer

The development and implementation of new amphiphiles based on natural resources rather than petrochemical precursors is an essential requirement due to their feedstock depletion and adverse environmental impacts. In addition, the use of bio-based surfactants can provide unique characteristics and improve the properties and versatility of the colloidal systems in which they are applied, such as emulsions. Here, the emulsification properties of a synthesized biocompatible mannose-based surfactant were investigated. Its behavior was evaluated in the presence of four different natural oils (castor, sunflower, olive and soybean) as well as two different aqueous phases (pure water and phosphate-buffered saline). The results highlighted its interest as surfactant in O/W nanoemulsions for all tested oil and aqueous phases, using a low-energy preparation protocol and relatively low surfactant concentrations. Furthermore, the mannose groups present on the polar head of the surfactant and adsorbed on the surface of the emulsion droplets were shown to retain their native biological properties. The specific mannose-concanavalin A binding was observed in vitro by the designed nanoemulsions, revealing the biorecognition properties of the surfactant and its potential applicability as a nanocarrier.