Supramolecular Functionalizable Linear–Dendritic Block Copolymers for the Preparation of Nanocarriers by Microfluidics

Hybrid linear–dendritic block copolymers (LDBCs) having dendrons with a precise number of peripheral groups that are able to supramolecular bind functional moieties are challenging materials as versatile polymeric platforms for the preparation of functional polymeric nanocarriers. PEG2k-b-dxDAP LDBCs that are based on polyethylene glycol (PEG) as hydrophilic blocks and dendrons derived from bis-MPA having 2,6-diacylaminopyridine (DAP) units have been efficiently synthesized by the click coupling of preformed blocks, as was demonstrated by spectroscopic techniques and mass spectrometry. Self-assembly ability was first checked by nanoprecipitation. A reproducible and fast synthesis of aggregates was accomplished by microfluidics optimizing the total flow rate and phase ratio to achieve spherical micelles and/or vesicles depending on dendron generation and experimental parameters. The morphology and size of the self-assemblies were studied by TEM, Cryogenic Transmission Electron Microscopy (cryo-TEM), and Dynamic Light Scattering (DLS). The cytotoxicity of aggregates synthesized by microfluidics and the influence on apoptosis and cell cycle evaluation was studied on four cell lines. The self-assemblies are not cytotoxic at doses below 0.4 mg mL−1. Supramolecular functionalization using thymine derivatives was explored for reversibly cross-linking the hydrophobic blocks. The results open new possibilities for their use as drug nanocarriers with a dynamic cross-linking to improve nanocarrier stability but without hindering disassembly to release molecular cargoes.

Facile topological transformation of ABA triblock copolymers into multisite, single-chain-folding and branched multiblock copolymers via sequential click coupling and anthracene chemistry

Telechelic PtBA-b-PSt-b-PtBA copolymers were designed to achieve on-demand topological transformation into multisite, single-chain-folding and branched multiblock copolymers via click/click-like reactions.

Rapid access to discrete and monodisperse block co-oligomers from sugar and terpenoid toward ultrasmall periodic nanostructures

Discrete block co-oligomers (BCOs) are gaining considerable attention due to their potential to form highly ordered ultrasmall nanostructures suitable for lithographic templates. However, laborious synthetic routes present a major hurdle to the practical application. Herein, we report a readily available discrete BCO system that is capable of forming various self-assembled nanostructures with ultrasmall periodicity. Click coupling of propargyl-functionalized sugars (containing 1–7 glucose units) and azido-functionalized terpenoids (containing 3, 4, and 9 isoprene units) afforded the discrete and monodisperse BCOs with a desired total degree of polymerization and block ratio. These BCOs microphase separated into lamellar, gyroid, and cylindrical morphologies with the domain spacing (d) of 4.2–7.5 nm. Considering easy synthesis and rich phase behavior, presented BCO systems could be highly promising for application to diverse ~4-nm nanofabrications.

Synthesis of Organic–Inorganic Hybrid Nanocomposites via a Simple Two-Phase Ligands Exchange

The surface of nanocrystals (NCs) was precisely engineered with bifunctional ligands via a simple yet effective two-phase ligand exchange strategy where the introduction of bifunctional ligands and displacement of insulating aliphatic ligands are simultaneously occurred. This is advantageous compared to conventional ligands exchange procedure where the desired ligands are often introduced through two-step processes after treating NC surface with short mobile ligands such as pyridine or short amines. In this study, 4-azidobenzoic acid possessing carboxylic acid for binding with NCs and azide group for chemical coupling was utilized as bifunctional ligands. A correlation between the concentration and the efficiency of ligands replacement was corroborated by Fourier transform infrared (FTIR) spectroscopy and nuclear magnetic resonance (1H NMR) spectroscopy measurement. Lastly, organic–inorganic nanocomposites were crafted via click coupling between 1-octyne and azidobenzoic acid capped CdSe NCs. The success of coupling was substantiated by FTIR and 1H NMR.

A Multifunctional HBED-Type Chelator with Dual Conjugation Capabilities for Radiopharmaceutical Development

Bifunctional HBED chelators are hexadentate complexing ligands (chelators) that tightly coordinate to trivalent gallium and, additionally, are able to bind to bioactive molecules. In nuclear medicine, HBED-based radiopharmaceuticals are used as powerful radiotracers for tumor imaging. Among variants of bifunctional HBED chelators, HBED-CC is the most well-known; it possesses two terminal carboxylic acid groups that are able to undergo bioconjugation by amide-bond formation. However, to permit bioconjugation through click coupling, we previously modified the structure of HBED-CC and introduced HBED-NN chelator bearing two azide functions. We have now combined the conjugation capabilities of HBED-CC and HBED-NN chelators in one molecule and have created HBED-NC, which possesses both azide and carboxylic acid groups. The advantage of HBED-NC is that it provides options for constructing either monomeric or heterodimeric radiolabeling precursors. This work describes the synthesis of HBED-NC by either of two pathways.

Thiol-ene "Click" Synthesis and Pharmacological Evaluation of C-Glycoside sp2-Iminosugar Glycolipids

The unique stereoelectronic properties of sp2-iminosugars enable their participation in glycosylation reactions, thereby behaving as true carbohydrate chemical mimics. Among sp2-iminosugar conjugates, the sp2-iminosugar glycolipids (sp2-IGLs) have shown a variety of interesting pharmacological properties ranging from glycosidase inhibition to antiproliferative, antiparasitic, and anti-inflammatory activities. Developing strategies compatible with molecular diversity-oriented strategies for structure–activity relationship studies was therefore highly wanted. Here we show that a reaction sequence consisting in stereoselective C-allylation followed by thiol-ene “click” coupling provides a very convenient access to α-C-glycoside sp2-IGLs. Both the glycone moiety and the aglycone tail can be modified by using sp2-iminosugar precursors with different configurational profiles (d-gluco or d-galacto in this work) and varied thiols, as well as by oxidation of the sulfide adducts (to the corresponding sulfones in this work). A series of derivatives was prepared in this manner and their glycosidase inhibitory, antiproliferative and antileishmanial activities were evaluated in different settings. The results confirm that the inhibition of glycosidases, particularly α-glucosidase, and the antitumor/leishmanicidal activities are unrelated. The data are also consistent with the two later activities arising from the ability of the sp2-IGLs to interfere in the immune system response in a cell line and cell context dependent manner.

Efficient Synthesis of Heparinoid Bioconjugates for Tailoring FGF2 Activity at the Stem Cell-Matrix Interface

Heparan sulfate glycosaminoglycans (HS GAGs) attached to proteoglycans harbor high affinity binding sites for various growth factors (GFs) and direct their organization and activity across the cell-matrix interface. Here, we describe a mild and efficient method for generating HS-protein conjugates. The two-step process utilizes a “copper-free” click coupling between differentially sulfated heparinoids primed at their reducing end with an azide handle and a bovine serum albumin protein modified with complementary cyclooctyne functionality. When adsorbed on tissue culture substrates, the glycoconjugates served as extracellular matrix proteoglycan models with the ability to sequester FGF2 and influence mesenchymal stem cell proliferation based on the structure of their HS GAG component.