Search Results (16)

Click chemistry is highly valued in the design of polymeric biomaterials due to its ability to generate complex structures and localized surface modifications. However, prominent mechanisms in click chemistry, such as copper-catalyzed azide-alkyne cycloaddition (CuAAC), are inefficient for the synthesis and/or modification of biomaterials because they present significant limitations for in vivo applications. The presence of residual copper in the material is toxic and requires extensive purification, increasing production costs and hindering scalability and availability for in vivo applications. To overcome these limitations and ensure the safety and biocompatibility of materials, biorthogonal reactions such as strain-promoted azide-alkyne cycloaddition (SPAAC) have been developed. Thiol-ene/thiol-yne and Diels–Alder mechanisms are also relevant for the formation of robust polymer networks with specific characteristics and attractive advantages for generating biocompatible materials. These reactions not only improve cell integration and reduce fibrosis in in vivo applications but also enable the creation of functional structures for tissue regeneration. This review provides a comprehensive analysis of advances in the synthesis of biomaterials for tissue regeneration using hydrogels designed via click chemistry, as well as the various mechanisms and structural considerations. Full article

Click chemistry has become a powerful and flexible approach for designing hydrogels used in tissue engineering thanks to its high specificity, fast reaction rates, and compatibility with biological systems. In this review, we introduce the core principles of click chemistry, including efficiency, orthogonality, and modularity, and highlight the main types of reactions commonly used in hydrogel formation, such as azide-alkyne c-cloadditions, thiol-ene/yne reactions, Diels–Alder cycloadditions, and tetrazine–norbornene couplings. These chemistries allow researchers to create covalently crosslinked hydrogels that are injectable, responsive to environmental stimuli, biodegradable, or multifunctional. We also explore strategies to enhance bioactivity, such as incorporating peptides, growth factors, or extracellular matrix components, and enabling precise spatial and temporal control over biological cues. Click-based hydrogels have shown promise across a wide range of tissue engineering applications, from cartilage and skin repair to neural regeneration, corneal healing, and cardiovascular scaffolds, as well as in 3D bioprinting technologies. Despite the many advantages of click chemistry such as mild reaction conditions and customizable material properties, some challenges remain, including concerns around copper toxicity, the cost of specialized reagents, and scalability. Finally, we discuss the status of clinical translation, regulatory considerations, and future directions, including integration with advanced bio fabrication methods, the design of dual-click systems, and the emerging role of in vivo click chemistry in creating next-generation biomaterials. Full article

Cellulose tosylate (MCC-Tos) is a key derivative for surface modification and a crucial precursor for cellulose compatibilization in click reactions, enabling its functionalization for advanced applications. Replacing tosyl groups with alkyne groups broadens cellulose’s potential in biocompatible reactions, such as thiol-yne click chemistry and protein/enzyme immobilization. To achieve this, we optimized the heterogeneous synthesis of MCC-Tos using a Doehlert matrix statistical design, evaluating the influence and interaction of the reaction conditions. The optimized conditions—144 h reaction time, 10:1 molar ratio, and 30 °C—yielded a degree of substitution for tosyl groups (DS_tos) of 1.80, determined via elemental analysis and FTIR-ATR spectroscopy. The reaction kinetics followed a first-order model. A subsequent reaction with propargylamine produced aminopropargyl cellulose (MCC-P_NH), reducing DS_tos by 65%, which was confirmed via FTIR, and improving thermal stability by a margin of 30 °C (TGA/DTG). ¹³C CP/MAS NMR confirmed the alkyne group attachment, further validated via coupling an azide-functionalized coumarin through copper(I)-catalyzed alkyne-azide cycloaddition (CuAAC). Fluorescence microscopy and UV spectroscopy were used to estimate a substitution degree of 0.21. This study establishes a feasible route for synthesizing alkyne-functionalized cellulose, paving the way for eco-friendly materials, including protein/enzyme bioconjugates, composites, and advanced materials via thiol-yne and CuAAC reactions. Full article

Since its conceptualization, click chemistry in all its variants has proven to be a superior synthesis protocol, compared to conventional methods, for forming new covalent bonds under mild conditions, orthogonally, and with high yields. If a term like reactive resilience could be established, click reactions would be good examples, as they perform better under increasingly challenging conditions. Particularly, highly hindered couplings that perform poorly with conventional chemistry protocols—such as those used to conjugate biomacromolecules (e.g., proteins and aptamers) or multiple drugs onto macromolecular platforms—can be more easily achieved using click chemistry principles, while also promoting high stereoselectivity in the products. In this review, three molecular platforms relevant in the field of nanomedicine are considered: polymers/copolymers, cyclodextrins, and fullerenes, whose functionalization poses a challenge due to steric hindrance, either from the intrinsic bulk behavior (as in polymers) or from the proximity of confined reactive sites, as seen in cyclodextrins and fullerenes. Their functionalization with biologically active groups (drugs or biomolecules), primarily through copper-catalyzed azide–alkyne cycloaddition (CuAAC), strain-promoted azide–alkyne cycloaddition (SPAAC), inverse electron-demand Diels–Alder (IEDDA) and thiol–ene click reactions, has led to the development of increasingly sophisticated systems with enhanced specificity, multifunctionality, bioavailability, delayed clearance, multi-targeting, selective cytotoxicity, and tracking capabilities—all essential in the field of nanomedicine. Full article

Graft copolymers have gained significant importance in various fields due to their tunable functionality and well-defined architecture. However, there are still limitations due to the compatibility of monomers and functional groups depending on the polymerization mode. Click chemistry has solved this problem through its ability to easily and quantitatively link a wide range of polymers and functional groups. The combination of click chemistry, including copper-catalyzed azide-alkyne cycloaddition (CuAAC), thiol-ene, and thiol-yne reactions, with various polymerization techniques offers a promising solution for the robust and efficient preparation of graft copolymers with the desired architecture and functionality. In this review, we present successful applications of click chemistry in the production of well-defined graft copolymers with diverse functionalities such as for electronics, energy devices, biomedical applications, and nanotechnology. Full article

Background: The incorporation of radionuclides into peptides and larger biomolecules requires efficient and sometimes biorthogonal reaction conditions, to which click chemistry provides a convenient approach. Methods: Traditionally, click-based radiolabeling techniques have focused on classical click chemistry, such as copper(I)-catalyzed alkyne-azide [3+2] cycloaddition (CuAAC), strain-promoted azide-alkyne [3+2] cycloaddition (SPAAC), traceless Staudinger ligation, and inverse electron demand Diels–Alder (IEDDA). Results: However, newly emerging click-based radiolabeling techniques, including tyrosine-click, sulfo-click, sulfur(VI) fluoride exchange (SuFEx), thiol-ene click, azo coupling, hydrazone formations, oxime formations, and RIKEN click offer valuable alternatives to classical click chemistry. Conclusions: This review will discuss the applications of these techniques in peptide radiochemistry. Full article

The study delves into the use of the thiol-yne click reaction to enhance (bio)conjugation methodologies, particularly focusing on immobilizing biomolecules onto PLLA surfaces. The thiol-yne click reaction, known for its efficiency, selectivity, and versatility in forming carbon-sulfur bonds under mild conditions without transition metal catalysts, is explored for conjugating the fluorophore dansyl onto PLLA surfaces. This approach aims to broaden bioconjugation strategies beyond traditional methods like the Michael-type reaction, expanding their applicability to diverse biomolecules. Utilizing a photoinitiator and specific light for photo-immobilization, the thiol-yne click reaction offers spatial and temporal control, with the absence of transition metal catalysts mitigating concerns of cytotoxicity and metal contamination, rendering it suitable for biomedical applications. The objectives of this research encompass demonstrating the feasibility of the thiol-yne click reaction for surface functionalization and enriching bioconjugation strategies for tailoring PLLA surfaces, ultimately advancing biomedical technologies through precise control over surface properties and functionality. For this purpose, PLLA surfaces were activated through hydrolysis and amidation to introduce the activated alkyne moiety (PLLA-Alkyne), followed by photo-induced dansyl immobilization (PLLA-Dns) with Irgacure 651. Various surface characterization techniques, including SEM, WCA, XPS, ATR-FTIR, and fluorescence microscopy and spectroscopy, validated the successful conjugation. This metal-free method preserves the material’s bulk properties while enabling thiol-containing molecule immobilization. Full article

For the first time, a novel dithiomaleimides (DTM) based tetra-antennary GalNAc conjugate was developed, which enable both efficient siRNA delivery and good traceability, without incorporating extra fluorophores. This conjugate can be readily constructed by three click-type reactions, that is, amidations, thiol-dibromomaleimide addition and copper catalyzed azide–alkyne cycloaddition (CuAAC). And it also has comparable siRNA delivery efficiency, with a GalNAc L96 standard to mTTR target. Additionally, due to the internal DTMs, a highly fluorescent emission was observed, which benefited delivery tracking and reduced the cost and side effects of the extra addition of hydrophobic dye molecules. In all, the simple incorporation of DTMs to the GalNAc conjugate structure has potential in gene therapy and tracking applications. Full article

Hyaluronic acid (HA) hydrogels display a wide variety of biomedical applications ranging from tissue engineering to drug vehiculization and controlled release. To date, most of the commercially available hyaluronic acid hydrogel formulations are produced under conditions that are not compatible with physiological ones. This review compiles the currently used approaches for the development of hyaluronic acid hydrogels under physiological/mild conditions. These methods include dynamic covalent processes such as boronic ester and Schiff-base formation and click chemistry mediated reactions such as thiol chemistry processes, azide-alkyne, or Diels Alder cycloaddition. Thermoreversible gelation of HA hydrogels at physiological temperature is also discussed. Finally, the most outstanding biomedical applications are indicated for each of the HA hydrogel generation approaches. Full article

Petroleum contains a large number of heteroatomic compounds, but today, most of them are not efficiently utilized. The constant development of the sustainability concept recalls for rethinking the usage of fossil resources with improved chemical utility. In order to initiate research aimed at involving active petroleum compounds in chemical transformations, a new analytical method for product detection is needed. Here, we study the click reaction of thiols with alkynes, leading to the formation of α-vinyl sulfides directly in the petroleum environment. The reaction was carried out using an (IMes)Pd(acac)Cl catalyst, which demonstrated tolerance to petroleum components. In this study, the concentration of thiols ranged from 1 M to 0.01 M (from 8% to 0.1%). To detect products at low concentrations, a special alkyne labeled with an imidazole moiety was used. This approach made it possible to observe the formation of vinyl sulfides by electrospray ionization mass spectrometry (ESI-MS), which provides an opportunity for further optimization of the reaction conditions and future developments for the direct involvement of oil components in chemical reactions. Full article

A series of small molecules containing polar aromatic substituents and alkynes have been synthesized. One–pot preparations of polar aromatic molecules containing an alkynyl imine and alkynyl amide are reported. A one-pot preparation of a catechol containing an alkynyl amine was also attempted but in our hands it proved much better to synthesize this target molecule via a three step synthesis which we also report here. Full article

The demand for tailored, micrometer-scaled biomaterials in cell biology and (cell-free) biotechnology has led to the development of tunable microgel systems based on natural polymers, such as hyaluronic acid (HA). To precisely tailor their physicochemical and mechanical properties and thus to address the need for well-defined microgel systems, in this study, a bottom-up material guide is presented that highlights the synergy between highly selective bio-orthogonal click chemistry strategies and the versatility of a droplet microfluidics (MF)-assisted microgel design. By employing MF, microgels based on modified HA-derivates and homobifunctional poly(ethylene glycol) (PEG)-crosslinkers are prepared via three different types of click reaction: Diels–Alder [4 + 2] cycloaddition, strain-promoted azide-alkyne cycloaddition (SPAAC), and UV-initiated thiol–ene reaction. First, chemical modification strategies of HA are screened in-depth. Beyond the microfluidic processing of HA-derivates yielding monodisperse microgels, in an analytical study, we show that their physicochemical and mechanical properties—e.g., permeability, (thermo)stability, and elasticity—can be systematically adapted with respect to the type of click reaction and PEG-crosslinker concentration. In addition, we highlight the versatility of our HA-microgel design by preparing non-spherical microgels and introduce, for the first time, a selective, hetero-trifunctional HA-based microgel system with multiple binding sites. As a result, a holistic material guide is provided to tailor fundamental properties of HA-microgels for their potential application in cell biology and (cell-free) biotechnology. Full article

Series of multivalent α-l-fucoside containing glycoclusters and variously decorated l-fucosides were synthesized to find potential inhibitors of fucose-specific lectins and study the structure-binding affinity relationships. Tri- and tetravalent fucoclusters were built using copper-mediated azide-alkyne click chemistry. Series of fucoside monomers and dimers were synthesized using various methods, namely glycosylation, an azide-alkyne click reaction, photoinduced thiol-en addition, and sulfation. The interactions between compounds with six fucolectins of bacterial or fungal origin were tested using a hemagglutination inhibition assay. As a result, a tetravalent, α-l-fucose presenting glycocluster showed to be a ligand that was orders of magnitude better than a simple monosaccharide for tested lectins in most cases, which can nominate it as a universal ligand for studied lectins. This compound was also able to inhibit the adhesion of Pseudomonas aeruginosa cells to human epithelial bronchial cells. A trivalent fucocluster with a protected amine functional group also seems to be a promising candidate for designing glycoconjugates and chimeras. Full article

The core-shell structure molecularly imprinted magnetic nanospheres towards hypericin (Fe₃O₄@MIPs) were prepared by mercapto-alkyne click polymerization. The shape and size of nanospheres were characterized by dynamic light scattering (DLS) and transmission electron microscope (TEM). The nanospheres were analyzed by FTIR spectroscopy to verify the thiol-yne click reaction in the presence or absence of hypericin. The Brunauer–Emmet–Teller (BET) method was used for measuring the average pore size, pore volume and surface area. The Fe₃O₄@MIPs synthesized displayed a good adsorption capacity (Q = 6.80 µmol·g⁻¹). In addition, so-prepared Fe₃O₄@MIPs showed fast mass transfer rates and good reusability. The method established for fabrication of Fe₃O₄@MIPs showed excellent reproducibility and has broad potential for the fabrication of other core-shell molecularly imprinted polymers (MIPs). Full article

Ethanedithiol-functionalized polyisobutylene was prepared in one step by a photoinitiated thiol-ene “click” reaction starting from ethanedithiol and polyisobutylene (PIB). The functionalized oligomer product was then used as a soluble sequestrant for transition metals. This PIB-bound thioether-thiol ligand is phase selectively soluble in alkanes and it quantitatively sequesters common transition metals like Cu²⁺ and Pd²⁺ into an alkane phase, separating them from polar solvents in a biphasic liquid/liquid separation. The chelating thioether-thiol ligand was also successfully used to remove Cu and Pd transition metal catalyst residues from products in crude reaction mixtures in both azide/alkyne click reactions and cross-coupling reactions using a liquid/liquid extraction. Separation efficiencies exceeding 95% and in many cases 99% were achieved. Full article