Click Chemistry in Detecting Protein Modification.

Click chemistry, also known as "link chemistry," is an important molecular connection method that can achieve simple and efficient connections between specific small molecular groups at the molecular level. Click chemistry offers several advantages, including high efficiency, good selectivity, mild conditions, and few side reactions. These features make it a valuable tool for in-depth analysis of various protein posttranslational modifications (PTMs) caused by changes in cell metabolism during viral infection. This chapter considers the palmitoylation, carbonylation, and alkylation of STING and presents detailed information and experimental procedures for measuring PTMs using click chemistry.

In-situ activation of biomimetic single-site bioorthogonal nanozyme for tumor-specific combination therapy.

Copper-catalyzed click chemistry offers creative strategies for activation of therapeutics without disrupting biological processes. Despite tremendous efforts, current copper catalysts face fundamental challenges in achieving high efficiency, atom economy, and tissue-specific selectivity. Herein, we develop a facile "mix-and-match synthetic strategy" to fabricate a biomimetic single-site copper-bipyridine-based cerium metal-organic framework (Cu/Ce-MOF@M) for efficient and tumor cell-specific bioorthogonal catalysis. This elegant methodology achieves isolated single-Cu-site within the MOF architecture, resulting in exceptionally high catalytic performance. Cu/Ce-MOF@M favors a 32.1-fold higher catalytic activity than the widely used MOF-supported copper nanoparticles at single-particle level, as first evidenced by single-molecule fluorescence microscopy. Furthermore, with cancer cell-membrane camouflage, Cu/Ce-MOF@M demonstrates preferential tropism for its parent cells. Simultaneously, the single-site CuII species within Cu/Ce-MOF@M are reduced by upregulated glutathione in cancerous cells to CuI for catalyzing the click reaction, enabling homotypic cancer cell-activated in situ drug synthesis. Additionally, Cu/Ce-MOF@M exhibits oxidase and peroxidase mimicking activities, further enhancing catalytic cancer therapy. This study guides the reasonable design of highly active heterogeneous transition-metal catalysts for targeted bioorthogonal reactions.

Potential vs challenges of expanding the protein universe with genetic code expansion in eukaryotic cells.

Following decades of innovation and perfecting, genetic code expansion has become a powerful tool for in vivo protein modification. Some of the major hurdles that had to be overcome include suboptimal performance of GCE-specific translational components in host systems, competing cellular processes, unspecific modification of the host proteome and limited availability of codons for reassignment. Although strategies have been developed to overcome challenges, there is critical need for further improvement. Here we discuss the current state-of-the-art in genetic code expansion technology and the issues that still need to be addressed to unleash the full potential of this method in eukaryotic cells.

Phytotoxic and Cytogenetic Assessment of Glycerol Triazole Derivatives in Model Plants and Weeds.

Weed invasion represents a challenge for farmers, who typically manage it with herbicides. However, this approach raises concerns about environmental and human health, as well as increasing resistance in these plants with continued use. Therefore, exploring alternative methods, such as heterocyclic compounds, triazoles, is essential due to their biological and environmental relevance. This study aimed to evaluate the effects of twelve 1,2,3-triazoles on the germination and early development of Lactuca sativa, Bidens pilosa, and Lolium multiflorum, as well as their impact on cell division in the cells of L. sativa. Triazole derivatives 4a, 4b, 4c, 4g, 4h, 4i, 4k, and 4l exhibited phytotoxicity, showing varying levels of inhibition in germination, germination speed index, and root growth. Chlorinated compounds were the most detrimental to lettuce development. B. pilosa was notably affected by compounds 4h, 4i, 4k, and 4l, while L. multiflorum responded most to triazoles 4c and 4l, with effectiveness comparable to that of the herbicide glyphosate. All derivatives, except 4l, exhibited aneugenic mechanisms of action, and 4a, 4b, 4c, 4e, 4f, and 4g showed clastogenic effects. This study demonstrated the potential of triazoles as effective agents against weed growth, with mechanisms that warrant further investigation for agricultural applications.

Discovery of a new soft-bodied click-beetle genus from Namibia with a unique morphology leads to a modified diagnosis of Drilini (Coleoptera, Elateridae).

Drilini are soft-bodied predatory click beetles with incompletely metamorphosed females. Approximately 150 described species are distributed in the Afrotropical, Palaearctic and Oriental realms, with the highest diversity known from sub-Saharan Africa. In this study, we describe Namibdrilusalbertalleni gen. et sp. nov. from Namibia which brings the total number of genera in Drilini to 16. The discovery of this unique taxon sheds new light on the diversity and evolution of the enigmatic paedomorphic beetle lineage and is interesting for several reasons. This new species is the only known representative of Drilini that has unidentate mandibles and lacks a hook on the dorsal part of the aedeagal median lobe, two of the few characters heretofore used for the unambiguous identification of members of this group. Furthermore, based on its morphology it belongs to a group of genera (Drilus clade) which heretofore contained only taxa from the Palaearctic Realm. We provide an updated diagnosis of the tribe Drilini, as well as an updated diagnosis and an identification key for the genera of the Drilus clade based on adult males. Further, we explain how to easily recognize adult Drilini from similar-looking soft-bodied elateroids like Elateridae: Omalisinae, Rhagophthalmidae, and Lampyridae: Ototretinae.

Exploring the Utility of Cell-Penetrating Peptides as Vehicles for the Delivery of Distinct Antimalarial Drug Cargoes.

The devastating impact of malaria includes significant mortality and illness worldwide. Increasing resistance of the causative parasite, Plasmodium, to existing antimalarial drugs underscores a need for additional compounds with distinct modes of action in the therapeutic development pipeline. Here we showcase peptide-drug conjugates (PDCs) as an attractive compound class, in which therapeutic or lead antimalarials are chemically conjugated to cell-penetrating peptides. This approach aims to enhance selective uptake into Plasmodium-infected red blood cells and impart additional cytotoxic actions on the intraerythrocytic parasite, thereby enabling targeted drug delivery and dual modes of action. We describe the development of PDCs featuring four compounds with antimalarial activity - primaquine, artesunate, tafenoquine and methotrexate - conjugated to three cell-penetrating peptide scaffolds with varied antiplasmodial activity, including active and inactive analogs of platelet factor 4 derived internalization peptide (PDIP), and a cyclic polyarginine peptide. Development of this diverse set of PDCs featured distinct and adaptable conjugation strategies, to produce conjugates with in vitro antiplasmodial activities ranging from low nanomolar to low micromolar potencies according to the drug cargo and bioactivity of the partner peptide. Overall, this study establishes a strategic and methodological framework for the further development of dual mode of action peptide-drug antimalarial therapeutics.

Selenium(II)-Nitrogen Exchange (SeNEx) Chemistry: A Good Chemistry Suitable for Nanomole-Scale Parallel Synthesis, DNA-encoded Library Synthesis, and Bioconjugation.

The continuous development of click reactions with new connecting linkage is crucial for advancing the frontiers of click chemistry. Selenium-nitrogen exchange (SeNEx) chemistry, a versatile chemistry in click chemistry, represents an all-encompassing term for nucleophilic substitution events that replace nitrogen at an electrophilic selenium(II) center, enabling the flexible and efficient assembly of linkages around a Se(II) core. Several SeNEx chemistries have been developed inspired by the biochemical reaction between Ebselen and cysteine residue, and demonstrated significant potential in on-plate nanomole-scale parallel synthesis, selenium-containing DNA-encoded library (SeDEL) synthesis, as well as peptide and protein bioconjugation. This concept aims to present the origins, advancements, and applications of selenium(II)-nitrogen exchange (SeNEx) chemistry while also outlining the potential directions for future research in this field.

Chemically Self-Assembled Monolayer Semiconducting Single-Walled Carbon Nanotube-Based Biosensor Platform for Amyloid-ß Detection.

This paper presents a platform for amyloid-ß (Aß) biosensors, employing nearly monolayer semiconducting single-walled carbon nanotubes (sc-SWNTs) via click reaction. A high-purity sc-SWNT ink was obtained by employing a conjugated polymer wrapping method with the addition of silica gel. Aß detection involved monitoring the electrical resistances of the sc-SWNT layers. Electrical resistances increased rapidly corresponding to the concentration of amyloid-ß 1-42 (Aß1-42) peptides. Furthermore, we introduced Aß peptides onto the 1-pyrenebutanoic acid succinimidyl ester (PBASE) linker, confirming that only the chemical adsorption of the peptide by the antibody-antigen reaction yielded a significant change in electrical resistance. The optimized sensor exhibited a high sensitivity of 29% for Aß at a concentration of 10 pM. Notably, the biosensor platform featuring chemically immobilized sc-SWNT networks can be customized by incorporating various bioreceptors beyond Aß antibodies.

Construction of a chemiluminescent biosensor based on enzymatic extension and click chemistry for sensitive measurement of MGMT activity in human breast tissues.

O6-methylguanine methyltransferase (MGMT) is responsible for dealkylation of naturally occurring O6-methylguanines, and it is closely related with DNA replication, transcription, and cancers. Herein, we develop a chemiluminescent biosensor based on enzymatic extension and click chemistry for sensitive measurement of MGMT activity. When MGMT is present, the MGMT-catalyzed demethylation reaction initiates the cleavage of biotinylated dumbbell probes by PvuII restrictive enzyme, releasing two DNA fragments with 3'-OH end. The resultant DNA fragments can trigger terminal transferase (TdT)- and click chemistry-assisted isothermal amplification to obtain abundant G-rich sequences. The G-rich sequences can be captured by magnetic beads to produce a high chemiluminescence signal. This biosensor can greatly amplify the chemiluminescence signal, facilitating label-free and template-free measurement of MGMT. Especially, the introduction of dumbbell probe and PvuII enzyme can efficiently eliminate the false positive and improve the assay specificity. This biosensor possesses high sensitivity with a detection limit of 1.4 × 10-9 ng/µL, and it may accurately quantify the intracellular MGMT. Importantly, this biosensor can be used to screen the MGMT inhibitors and distinguish the MGMT level in breast tumor tissues and normal tissues, with great potential in drug discovery and cancer diagnosis.

Shear-Induced Cycloreversion Leading to Shear-Thinning and Autonomous Self-Healing in an Injectable, Shape-Holding Collagen Hydrogel.

In vivo injectable extracellular matrix (ECM) derived hydrogels that are suitable for cell encapsulation have always been the holy grail in tissue engineering. Nevertheless, these hydrogels still fall short today of meeting three crucial criteria: (a) flexibility on the injectability time window, (b) autonomous self-healing of the injected hydrogel, and (c) shape-retention under aqueous conditions. Here we report the development of a collagen-based injectable hydrogel, cross-linked by cycloaddition reaction between furan and maleimide groups, that (a) is injectable up to 48 h after preparation, (b) can undergo complete autonomous self-healing after injection, (c) can retain its shape and size over several years when stored in the buffer, (d) can be degraded within hours when treated with collagenase, (e) is biocompatible as demonstrated by in vitro cell-culture, and (f) is completely resorbable in vivo when implanted subcutaneously in rats without causing any inflammation.

A Site-Specific Click Chemistry Approach to Di-ubiquitylate H1 Variants Reveals Position-dependent Stimulation of the DNA Repair Protein RNF168.

Ubiquitylation of histone H2A at lysines 13 and 15 by the E3 ligase RNF168 plays a key role in orchestrating DNA double-strand break (DSB) repair, which is often deregulated in cancer. RNF168 activity is triggered by DSB signaling cascades, reportedly through K63-linked poly-ubiquitylation of linker histone H1. However, direct experimental evidence of this mechanism has been elusive, primarily due to the lack of methods to specifically poly-ubiquitylate H1. Here, we developed a versatile click-chemistry approach to covalently link multiple proteins in a site-specific, controlled, and stepwise manner. Applying this method, we synthesized H1 constructs bearing triazole-linked di-ubiquitin on four DNA repair-associated ubiquitylation hotspots (H1KxUb2, at K17, 46, 64 and 96). Integrated into nucleosome arrays, the H1KxUb2 variants stimulated H2A ubiquitylation by RNF168 in a position-dependent manner, with H1K17Ub2 showing the strongest RNF168 activation effect. Moreover, we show that di-ubiquitin binding is the driving force underlying RNF168 recruitment, introducing H1K17Ub2 into living U-2 OS cells. Together, our results support the hypothesis of poly-ubiquitylated H1 guiding RNF168 recruitment to DSB sites. Moreover, we demonstrate how the streamlined synthesis of H1KxUb2 variants enables mechanistic studies into RNF168 regulation, with potential implications for its inhibition in susceptible cancers.

Evaluation of transplant drench and foliar insecticide applications for wireworm (Coleoptera: Elateridae) management in sweetpotato.

The revocation of chlorpyrifos tolerances in 2022 left sweetpotato growers without their most important tool to combat a complex of soil-borne root pests that includes wireworms (Coleoptera: Elateridae). Since then, growers have reported increased root damage despite a rapid pivot to pyrethroid-based management systems to replace mechanically incorporated preplant chlorpyrifos broadcast sprays. Our goal was to evaluate the efficacy of alternative insecticide chemistries and application methods to expand the portfolio of management options for wireworms, specifically Conoderus spp. and Melanotus communis (Gyllenhal). We tested (i) insecticidal transplant water drenches and (ii) a foliar spray program targeting adult elaterids. We found that incorporating insecticides into transplant water reduced wireworm damage when compared to untreated transplant water. Our treatments included a recently registered meta-diamide, broflanilide, which represents a promising path to diversify active ingredients and shift away from an overreliance on preplant and post-directed pyrethroid soil sprays. Foliar spray plots had less damage than plots that did not receive foliar sprays. One benefit of adult-focused management is the availability of effective monitoring tools such as sex pheromones and blacklight trapping. Developing a robust adult monitoring program would enable more precise applications of foliar insecticides versus season-long prophylactic soil sprays targeting larvae. Our results demonstrated a significant benefit to both alternative delivery methods. These management alternatives could expand treatment options beyond traditional preplant and post-directed pyrethroid sprays.

Rational design and microwave-promoted synthesis of triclosan-based dimers: targeting InhA for anti-mycobacterial profiling.

A set of alkyl-/1H-1,2,3-triazole-based dimers was strategically designed and synthesized to evaluate their in vitro anti-mycobacterial activities against Mycobacterium tuberculosis and the non-tuberculous Mycobacterium abscessus strains. Systematic variations in the nature (alkyl/1H-1,2,3-triazole) and positioning of the linker were implemented based on the docking scores observed in the binding sites identified in the crystal structures of InhA from M. tuberculosis and M. abscessus. However, the in vitro evaluation results revealed that the synthesized compounds did not exhibit inhibitory effects on the growth of mycobacteria, even at the highest tested concentrations. The elevated lipophilicity values determined through ADMET studies for these synthesized dimers might be a contributing factor to their poor activity profiles.

Facile fabrication of a thermal/pH responsive IPN hydrogel drug carrier based on cellulose and chitosan through simultaneous dual-click strategy.

Herein, an interpenetrating network hydrogel (IPN-Gel) based on cellulose and chitosan was synthesized via simultaneous amino-anhydride and azide-alkyne click reaction in water in one pot. The samples were characterized by various analytical methods including FTIR, SEM, XRD, XPS, 1H NMR and so forth. The fabrication conditions were optimized by single factor experiments with water uptake (WU) and gel mass fraction (GMF) as two indexes. The WU and GMF of the IPN-Gel prepared under optimized conditions were 1192.37 % and 74.00 %, respectively. Its WU descended with the ascension in temperature, and first descended and then gradually ascended with the ascension in pH, confirming that the IPN-Gel had thermal/pH dual responsiveness. Using 5-Fu as a model drug, the release behavior of 5-Fu in IPN-Gel was explored. Its release behavior could be regulated by changing temperature and pH values, and it followed the Korsmeyer Peppas model. The viability of 4 T1 cells and HUVEC cells exceeded 80 % after 48 h of incubation at a high concentration of 200 µg/mL IPN-Gel, and hemolytic percentage was below the allowed limit of 5 %. The study provides a new strategy for the preparation of the IPN-Gel with biocompatibility, swelling reversibility and controllable drug release.

Stretchable Heat Transfer Eco-Materials: Mesogen Grafted NR-Based Nanocomposites with High Thermal Conductivity and Low Dielectric Constant.

Biomass-based functional polymers have received significant attention across various fields, in view of eco-friendly human society and sustainable growth. In this context, there are efforts to functionalize the biomass polymers for next-generation polymer materials. Here, stretchable heat transfer materials are focused on which are essential for stretchable electronics and future robotics. To achieve this goal, natural rubber (NR) is chemically modified with a thiol-terminated phenylnaphthalene (TTP), and then utilized as a thermally conductive NR (TCNR) matrix. Hexagonal boron nitride (h-BN), renowned for its high thermal conductivity and low electrical conductivity, is incorporated as a filler to develop stretchable heat transfer eco-materials. The optimized TCNR/h-BN composite elongates to 140% due to great elasticity of NR, and exhibits excellent dielectric properties (a low dielectric constant of 2.26 and a low dielectric loss of 0.006). Furthermore, synergetic phonon transfer of phenylnaphthalene crystallites and h-BN particles in the composite results in a high thermal conductivity of 0.87 W m-1 K-1. The outstanding thermal, mechanical, and dielectric properties of the newly developed TCNR/h-BN composite enable the successful demonstration as stretchable and shape-adaptable thermal management materials.

Highly precise strategy of polygalacturonic acid microcarriers functionalized with zwitterions and specific peptides for MSC screening.

Microcarriers for large-scale cell culture have a broader prospect in cell screening compared with the traditional high cost, low efficiency, and cell damaging methods. However, the equal biological affinity to cells has hindered its application. Therefore, based on the antifouling strategy of zwitterionic polymer, we developed a cell-specific microcarrier (CSMC) for shielding non-target cells and capturing mesenchymal stem cells (MSCs), which has characteristics of high biocompatibility, low background noise and high precision. Briefly, [2-(methacryloyloxy) ethyl] dimethyl-(3-sulfopropyl) ammonium hydroxide and glycidyl methacrylate were grafted onto polygalacturonic acid, respectively. The former built a hydration layer through solvation to provide an excellent antifouling surface, while the latter provided active sites for the click reaction with sulfhydryl-modified cell-specific peptides, resulting in rapid immobilization of peptides. This method is applicable to the vast majority of polysaccharide materials. The accurate capture ratio of MSCs by CSMC in a mixed multicellular environment is >95 % and the proliferation rate of MSCs on microcarriers is satisfactory. In summary, this grafting strategy of bioactive components lays a foundation for the application of polysaccharide materials in the biomedical field, and the specific adhesive microcarriers also open up new ideas for the development of stem cell screening as well.

Protective Coatings Based on the Organosilicon Derivatives of Fatty Acids Obtained by the Thiol-Ene Click Reaction.

This article describes the synthesis of a hydrophobic protective coating for concrete based on a silane derivative of fatty acids. The coating was obtained through a thiol-ene click addition reaction using methyl oleate and 3-mercaptopropyltrimethoxysilane in the presence of the photoinitiator 2,2-dimethoxy-2-phenylacetophenone (DMPA). This reaction proved to be more efficient compared with other tested (photo)initiators, considering the double bond conversion of oleate. The coating was applied to concrete using two methods: immersion and brushing. Both methods exhibited similar consumption of methyl oleate-based silane (UVMeS) at approximately 20 g/m2. The hydrophobic properties of the coatings were evaluated based on the contact angle, which for the modified surfaces was above 93°, indicating their hydrophobic nature. The penetration depth of the silane solution into the concrete was also studied; it was 5-7 mm for the immersion method and 3-5 mm for the brushing method. The addition of tetraethoxysilane (TEOS) to the silane solution slightly improved the barrier properties of the coating.

Rapid preparation of injectable dual-network hydrogels for biomedical applications using UV-triggered sulfhydryl click reactions.

The use of hydrogels to mimic natural cartilage implantation can effectively solve the current problems of insufficient cartilage donors and low rate of injury healing. In particular, injectable hydrogels are less invasive in clinical applications and better able to fill uneven injury surfaces. Here, we prepared NorCS and CS-SH by modifying chitosan with 5-norbornene-2-carboxylic acid and N-Acetyl-L-cysteine, respectively. Dual-network hydrogels were prepared by using UV-triggered thiol-ene click reaction between NorCS and CS-SH and the metal coordination between SA and Ca2+. The prepared hydrogels can be cross-linked quickly and exhibit excellent degradability, self-healing and injectable properties. At the same time, the hydrogel also showed good cytocompatibility and could significantly restore the motor function of mice. This study provides an effective strategy for preparing injectable hydrogels capable of rapid cross-linking.

Effects of verbatim repetition of the headline message on the proceed button on click-through rates in online retail.

For online retailers, increasing click-through rates and reducing dropout rates are critical to success. In this study, we examine the effect of verbatim repetition of the website's headline message on the proceed button, based on research on processing fluency. In our field study involving 956 online platform visitors, we found that verbatim repetitions of the header message on the proceed button resulted in an increase in the conversion rate by more than 10 percentage points compared to gist repetitions and new messages. Our findings highlight the importance of simple verbatim features and demonstrate the successful application of processing fluency research to impact consumer behavior.

A New Class of Mechano-Responsive PolyureThane Via Anthracene -TAD Diels-Alder (DA) Click Chemistry.

Smart or stimuli-responsive polymers have garnered significant interest in the scientific community due to their response to different stimuli like pH, temperature, light, mechanical force, etc. Mechanophoric polymer is an intriguing class of smart polymers that respond to external mechanical force by producing fluorescent moieties and can be utilized for damage detection and stress-sensing assessment. In recent reports on mechanophoric polymers, different mechanophoric motifs such as spiropyran, rhodamine, coumarin, etc. are explored. This investigation reports a new kind of mechanophoric polyurethane (PU) adduct based on Diels-Alder (DA) click chemistry. Here, an anthracene(An)-end capped tri-armed urethane system is synthesized, followed by a DA reaction using bis-(1,2,4-triazoline-3,5-dione) (bis-TAD) derivative. The incorporation of bis-TAD in the urethane system renders the anthracene inactive ("turn-off") by dismantling its conjugation as a result of a successful DA reaction. The soft PU translated into a harder material through bis-TAD linkages between polymer chains as evident from nanoindentation (NINT) analysis. The resulting material reverts back to its fluorescent "turned-on" mode owing to a force-accelerated retro-Diels-Alder (r-DA) reaction. Besides the mechanophoric attributes, the material demonstrates self-healing behavior examined by microscopic investigations. This innovative approach can be a potential route to design responsive polymers with dynamic functionalities for advanced material applications.