Recent advances in selective mono-/dichalcogenation and exclusive dichalcogenation of C(sp2)-H and C(sp3)-H bonds.

Organochalcogen compounds are prevalent in numerous natural products, pharmaceuticals, agrochemicals, polymers, biological molecules and synthetic intermediates. Direct chalcogenation of C-H bonds has evolved as a step- and atom-economical method for the synthesis of chalcogen-bearing compounds. Nevertheless, direct C-H chalcogenation severely lags behind C-C, C-N and C-O bond formations. Moreover, compared with the C-H monochalcogenation, reports of selective mono-/dichalcogenation and exclusive dichalcogenation of C-H bonds are relatively scarce. The past decade has witnessed significant advancements in selective mono-/dichalcogenation and exclusive dichalcogenation of various C(sp2)-H and C(sp3)-H bonds via transition-metal-catalyzed/mediated, photocatalytic, electrochemical or metal-free approaches. In light of the significance of both mono- and dichalcogen-containing compounds in various fields of chemical science and the critical issue of chemoselectivity in organic synthesis, the present review systematically summarizes the advances in these research fields, with a special focus on elucidating scopes and mechanistic aspects. Moreover, the synthetic limitations, applications of some of these processes, the current challenges and our own perspectives on these highly active research fields are also discussed. Based on the substrate types and C-H bonds being chalcogenated, the present review is organized into four sections: (1) transition-metal-catalyzed/mediated chelation-assisted selective C-H mono-/dichalcogenation or exclusive dichalcogenation of (hetero)arenes; (2) directing group-free selective C-H mono-/dichalcogenation or exclusive dichalcogenation of electron-rich (hetero)arenes; (3) C(sp3)-H dichalcogenation; (4) dichalcogenation of both C(sp2)-H and C(sp3)-H bonds. We believe the present review will serve as an invaluable resource for future innovations and drug discovery.

Merging C-H Bond Activation, Alkyne Insertion, and Rearrangements by Rh(III)-Catalysis: Oxindole Synthesis from Nitroarenes and Alkynes.

We report a Rh(III)-catalyzed ortho-C-H bond functionalization of nitroarenes with 1,2-diarylalkynes and carboxylic anhydrides. The reaction unpredictably affords 3,3-disubstituted oxindoles with the formal reduction of the nitro group under redox-neutral conditions. Besides good functional group tolerance, this transformation allows the preparation of oxindoles with a quaternary carbon stereocenter using nonsymmetrical 1,2-diarylalkynes. This protocol is facilitated by the use of a functionalized cyclopentadienyl (CpTMP*)Rh(III) [CpTMP* = 1-(3,4,5-trimethoxyphenyl)-2,3,4,5-tetramethylcyclopentadienyl] catalyst we developed, which combines an electron-rich character with an elliptical shape. Mechanistic investigations, including the isolation of three rhodacyle intermediates and extensive density functional theory calculations, indicate that the reaction proceeds through nitrosoarene intermediates via a cascade of C-H bond activation─O-atom transfer─[1,2]-aryl shift─deoxygenation─N-acylation.

A spatiotemporally regulated transcriptional complex underlies heteroblastic development of leaf hairs in Arabidopsis thaliana.

Heteroblasty refers to a phenomenon that a plant produces morphologically or functionally different lateral organs in an age-dependent manner. In the model plant Arabidopsis thaliana, the production of trichomes (epidermal leaf hairs) on the abaxial (lower) side of leaves is a heteroblastic mark for the juvenile-to-adult transition. Here, we show that the heteroblastic development of abaxial trichomes is regulated by a spatiotemporally regulated complex comprising the leaf abaxial fate determinant (KAN1) and the developmental timer (miR172-targeted AP2-like proteins). We provide evidence that a short-distance chromatin loop brings the downstream enhancer element into close association with the promoter elements of GL1, which encodes a MYB transcription factor essential for trichome initiation. During juvenile phase, the KAN1-AP2 repressive complex binds to the downstream sequence of GL1 and represses its expression through chromatin looping. As plants age, the gradual reduction in AP2-like protein levels leads to decreased amount of the KAN1-AP2 complex, thereby licensing GL1 expression and the abaxial trichome initiation. Our results thus reveal a novel molecular mechanism by which a heteroblastic trait is governed by integrating age and leaf polarity cue in plants.

A scheme for rapid evaluation of the intermolecular three-body polarization effect in water clusters.

The ability to accurately and rapidly evaluate the intermolecular many-body polarization effect of the water system is very important for computer simulations of biomolecule in aqueous. In this paper, a scheme is proposed based on the polarizable dipole-dipole interaction model and used to rapidly estimate the intermolecular many-body polarization effect in water clusters. We use a bond-dipole-based polarization function to evaluate the polarization energy. We regard two OH bonds of a water molecule as two bond-dipoles and set the permanent OH bond-dipole moment of a water molecule to be 1.51 Debye. We estimate the induced OH bond-dipole moment via a simple formula in which only one correction factor is needed. This scheme is then applied to tens of water clusters to calculate the three- and four-body interaction energies. The three-body interaction energies of 93 water clusters produced by our scheme are compared with those produced by the counterpoise-corrected CCSD(T)/aug-cc-pVDZ, MP2/aug-cc-pVDZ, M06-2X/jul-cc-pVTZ methods, by the AMOEBApro13, iAMOEBA, AMOEBA+, AMOEBA+(CF) methods, and by the MB-pol method. The four-body interaction energies of 47 water clusters yielded by our scheme are compared with those yielded by the counterpoise-corrected MP2/aug-cc-pVDZ and M06-2X/ jul-cc-pVTZ methods, by the AMOEBApro13, AMOEBA+, AMOEBA+(CF) methods, and by the MB-pol method. The comparison results show that the scheme proposed in this paper can reproduce the counterpoise-corrected CCSD(T)/aug-cc-pVDZ three-body interaction energies and reproduce the counterpoise-corrected MP2/aug-cc-pVDZ four-body interaction energies both accurately and efficiently. We anticipate the scheme proposed here can be useful for computer simulations of liquid water and aqueous solutions.

From bonds to interactions: comprehensive molecular characterization via polarizable bond-dipole approach.

Accurately characterizing molecular interactions stands as a pivotal requirement for ensuring the reliability of molecular dynamics simulations. In line with our bond-dipole-based interaction model proposed by Gao et al. [X.-C. Gao, Q. Hao and C.-S. Wang, J. Chem. Theory Comput., 2017, 13, 2730-2741.], we have implemented an efficient and concise approach to compute electrostatic potential. This methodology capitalizes on the polarizable nature of chemical bond dipoles, resulting in a model of remarkable simplicity. In this study, we have revised the polarizable bond-dipole-based force field (PBFF) through the meticulous curation of quantum chemical data sets. These data sets encompass a comprehensive collection of 40 000 conformations, including those of water, methylamine, methanol, and N-methylacetamide. Additionally, we incorporate 520 hydrogen-bonded dimers into our data sets. In pursuit of enhanced accuracy in molecular dynamics simulations and a more faithful representation of potential energy landscapes, we undertook the re-optimization of the nonbonded parameters within the PBFF framework. Concurrently, we intricately fine-tuned the bonded parameters. The results of our comprehensive evaluation denote that this newly optimized force field method adeptly and efficiently computes structural characteristics, harmonic frequencies, and interaction energies. Overall, this study provides further validation for the applicability of PBFF in molecular dynamics simulations.

NBR2/miR-561-5p/DLC1 axis inhibited the development of multiple myeloma by activating the AMPK/mTOR pathway to repress glycolysis.

Long non-coding RNA NBR2 exerts a tumor-suppressive effect in a variety of cancers, but its role in multiple myeloma (MM) is unclear. This article will elucidate the role of NBR2 in MM. The expressions of NBR2, miR-561-5p, and deleted in liver cancer 1 (DLC1) in MM cell lines were determined by quantitative real time polymerase chain reaction (qRT-PCR). The regulatory relationship of the NBR2/miR-561-5p/DLC1 axis was predicted by bioinformatics and confirmed via a dual-luciferase reporter assay. The effect of NBR2 on the biological behavior of MM cells was verified by loss- and gain-of-function experiments (cell counting kit-8, colony formation, flow cytometry, extracellular acidification rate, and lactate production measurement). The effects of the NBR2/miR-561-5p axis on the biological behavior of MM cells, the activation of the AMPK/mTOR signaling pathway (western blot), and DLC1 expression (western blot) were verified by rescue experiments. The upregulation of NBR2 in MM cell lines induced a decrease in the viability, proliferation capacity, glycolysis, and lactic acid production, and an increase in apoptosis of MM cells. NBR2 regulated the biological behavior of MM cells and the activation of the AMPK/mTOR signaling pathway by targeting miR-561-5p. DLC1 was the target gene of miR-561-5p and the protein expression of DLC1 was regulated by the NBR2/miR-561-5p axis. Collectively, NBR2/miR-561-5p/DLC1 axis inhibits the development of MM by activating the AMPK/mTOR pathway to repress glycolysis.

Chromosomal-level genome assembly of the semi-dwarf rice Taichung Native 1, an initiator of Green Revolution.

Here we report the 409.5 Mb chromosome-level assembly of the first bred semi-dwarf rice, the Taichung Native 1 (TN1), which served as the template for the development of the Green Revolution (GR) cultivar IR8 "miracle rice". We sequenced the TN1 genome utilizing multiple platforms and produced PacBio long reads, Illumina paired-end reads, Illumina mate-pair reads and 10x Genomics linked reads. We used a hybrid approach to assemble the 226× coverage of sequences by a combination of de novo and reference-guided approaches. The assembled TN1 genome has an N50 scaffold size of 33.1 Mb with the longest measuring 45.5 Mb. We annotated 37,526 genes, in which 24,102 (64.23%) were assigned Blast2GO annotations. The genome has 4672 or 95.4% complete BUSCOs and a repeat content of 51.52%. We developed our own method of creating a GR pangenome using the orthologous relationships of the proteins of TN1, IR8, MH63 and IR64, identifying 16,999 core orthologue groups of Green Revolution. From the pangenome, we identified a set of shared and unique gene ontology terms for the accessory clusters, characterizing TN1, IR8, MH63 and IR64. This TN1 genome assembly and GR pangenome will be a resource for new genomic discoveries about Green Revolution, and for improving the disease and insect resistances and the yield of rice.

Understanding the Effect of Conformational Rigidity on Rheological Behavior and Formation of Polysaccharide-Based Hybrid Hydrogels.

The importance of conformational rigidity on macroscopic rheological properties was revealed using two model polysaccharides, namely, xanthan gum and hyaluronic acid. Xanthan gum has a rigid tertiary conformation due to its ordered double-helical structure, and the interactions between the tertiary structures result in the formation of a network/quaternary structure. In comparison, hyaluronic acid possesses a relatively flexible tertiary conformation due to its secondary random coil structure. Xanthan gum exhibits a much stronger shear thinning and more solidlike behavior compared to hyaluronic acid, owing to its network/quaternary structure. The rigid tertiary structure and the presence of a network/quaternary structure also endow xanthan gum with better resistance against environmental changes (e.g., salt and/or urea addition, temperature change) compared to hyaluronic acid. The network/quaternary structure allows xanthan gum to form gels with chitosan via electrostatic interactions when using the vapor-induced gelation technique, which is not possible for hyaluronic acid due to its flexible tertiary conformation under similar conditions.

Robust Cobalt Catalyst for Nitrile/Alkyne [2+2+2] Cycloaddition: Synthesis of Polyarylpyridines and Their Mechanochemical Cyclodehydrogenation to Nitrogen-Containing Polyaromatics*.

The transition-metal-catalyzed [2+2+2] cycloaddition of nitriles and alkynes is an established synthetic approach to pyridines; however, these cycloadditions often rely on the use of tethered diynes or cyanoalkynes as one of the reactants. Thus, examples of efficient, fully intermolecular catalytic [2+2+2] pyridine synthesis, especially those employing unactivated nitriles and internal alkynes leading to pentasubstituted pyridines, remain scarce. Herein, we report on simple and inexpensive catalytic systems based on cobalt(II) iodide, 1,3-bis(diphenylphosphino)propane, and Zn that promote [2+2+2] cycloaddition of various nitriles and diarylacetylenes for the synthesis of a broad range of polyarylated pyridines. DFT studies support a reaction pathway involving oxidative coupling of two alkynes, insertion of the nitrile into a cobaltacyclopentadiene, and C-N reductive elimination. The resulting tetra- and pentaarylpyridines serve as precursors to hitherto unprecedented nitrogen-containing polycyclic aromatic hydrocarbons via mechanochemically assisted multifold reductive cyclodehydrogenation.

Cobalt/Lewis Acid Catalysis for Hydrocarbofunctionalization of Alkynes via Cooperative C-H Activation.

A catalytic system comprising a cobalt-diphosphine complex and a Lewis acid (LA) such as AlMe3 has been found to promote hydrocarbofunctionalization reactions of alkynes with Lewis basic and electron-deficient substrates such as formamides, pyridones, pyridines and related azines, imidazo[1,2-a]pyridines, and azole derivatives through site-selective C-H activation. Compared with known Ni/LA catalytic systems for analogous transformations, the present catalytic systems not only feature convenient setup using inexpensive and bench-stable precatalyst and ligand such as Co(acac)3 and 1,3-bis(diphenylphosphino)propane (dppp) but also display distinct site-selectivity toward C-H activation of pyridone and pyridine derivatives. In particular, a completely C4-selective alkenylation of pyridine has been achieved for the first time. Meanwhile, the present catalytic system proved to promote exclusively C5-selective alkenylation of imidazo[1,2-a]pyridine derivatives. Mechanistic studies including DFT calculations on the Co/Al-catalyzed addition of formamide to alkyne have suggested that the reaction involves cleavage of the carbamoyl C-H bond as the rate-limiting step, which proceeds through a ligand-to-ligand hydrogen transfer (LLHT) mechanism leading to an alkenyl(carbamoyl)cobalt intermediate.

Photoredox Catalysis for Building C-C Bonds from C(sp2)-H Bonds.

Transition metal-catalyzed C-H bond functionalizations have been the focus of intensive research over the last decades for the formation of C-C bonds from unfunctionalized arenes, heteroarenes, alkenes. These direct transformations provide new approaches in synthesis with high atom- and step-economy compared to the traditional catalytic cross-coupling reactions. However, such methods still suffer from several limitations including functional group tolerance and the lack of regioselectivity. In addition, they often require harsh reaction conditions and some of them need the use of strong oxidant, in a stoichiometric amount, avoiding these processes to be truly eco-friendly. The use of photoredox catalysis has contributed to a significant expansion of the scope of C(sp2)-H bond functionalizations which include the direct arylations, (perfluoro)alkylations, acylations, and even cyanations. Most of these transformations involve the photochemical induced generation of a radical followed by its regioselective addition to arenes, heteroarenes, or alkenes, leading to the building of a new C(sp2)-C bond. The use of photoredox catalysis plays crucial roles in these reactions promoting electron transfer, enabling the generation of radical species and single electron either oxidation or reduction. Such reactions operating at room temperature allow the building of C-C bonds with high chemo-, regio-, or stereoselectivity. This review surveys the formation of C(sp2)-C bonds initiated by photoredox catalysis which involves a C(sp2)-H bond functionalization step, describes the advantages compared to traditional C(sp2)-H bond functionalizations, and presents mechanistic insights into the role played by the photoredox catalysts.

Tribological Behavior of Surface-Immobilized Novel Biomimicking Multihierarchical Polymers: The Role of Structure and Surface Attachment.

The tribological properties of two novel biomimetic multihierarchical polymers, synthesized by covalently linking single bottlebrush polymers onto a hyaluronic acid (HA) backbone, were investigated in the boundary lubrication regime using the surface forces apparatus. The polymers were immobilized on flat substrates, and their lubrication properties and wear resistance were investigated in aqueous media in the absence of a polymer reservoir (i.e., no free polymer chains in the surrounding medium) in order to better reveal the underlying mechanism of surface-attached biomimetic polymers. The effects of composition, structure, and, more particularly, surface attachment (physisorbed vs chemisorbed) on the tribological properties were investigated and compared with other biomimicking systems reported in the literature. The covalently surface attached bottlebrushes allowed wear resistance between sliding surfaces to be significantly improved, compared to physisorbed bottlebrushes, with a constant coefficient of friction (10-1) of up to few tens of MPa. The results confirm that surface-attached bottlebrushes on their own are not responsible for the extremely low friction often reported in the literature or found in articular joints. Moreover, the study confirmed that the irreversible attachment of bottlebrushes, or multihierarchical polymer layers, to surfaces is crucial to improving wear resistance between sliding surfaces in aqueous media.

Metal-free C(sp3)-H bond sulfonyloxylation of 2-alkylpyridines and alkylnitrones.

Pyridin-2-ylmethyl tosylate derivatives are obtained in high yields from 2-alkylpyridine 1-oxides via a [3,3]-sigmatropic rearrangement of the adduct between 2-alkylpridine 1-oxides with benzenesulfonyl chlorides. Moreover, alkylnitrones also undergo [3,3]-sigmatropic rearrangement to give α-tosylated ketones after hydrolysis. Substitution reactions with nucleophiles then lead to diverse useful functionalizations for the synthesis of pincer ligands.

Mapping and comparative proteomic analysis of the starch biosynthetic pathway in rice by 2D PAGE/MS.

KEY MESSAGE: Our results not only provide a comprehensive overview of the starch biosynthetic pathway in the developing endosperm but also reveal some important protein markers that regulate the synthesis of starch. In human diets, rice (Oryza sativa L.) is an important source of starch, a substantial amount of which is accumulated in developing endosperm. A better understanding of the complicated pathways involved in starch biosynthesis is needed to improve the yield and quality of rice and other cereal crops through breeding. One pure line rice mutant, SA0419, was induced from a wild-type rice, TNG67, by sodium azide mutagenesis; therefore, TNG67 and SA0419 share the same genetic background. SA0419 is, however, a unique glutinous rice with a lower amylose content (8%) than that of TNG67 (20%), and the grains of SA0419 develop earlier and faster than those of TNG67. In this study, we used a comparative proteomic analysis to identify the differentially expressed proteins that may explain the differences in starch biosynthesis and the characteristics of TNG67 and SA0419. A gel-based proteomic approach was applied to profile the expressed proteome in the developing endosperm of these two rice varieties by nano-LC/MS/MS. Several over-expressed proteins were found in SA0419, such as plastidial ADP-glucose pyrophosphorylase (AGPase), phosphoglucomutase (PGM), pyrophosphate-fructose 6-phosphate 1-phosphotransferase (PFP), 6-phosphofructokinase (PFK), pyruvate phosphate dikinase (PPDK), starch branching enzymes (SBE) and starch debranching enzyme (SDBE), with those proteins mainly being involved in the pathways of starch metabolism and PPDK-mediated gluconeogenesis. Those over-expressed enzymes may contribute to the relatively early development, similar starch accumulation and rapid grain filling of SA0419 as compared with TNG67. This study provides a detailed biochemical description of starch biosynthesis and related information regarding a unique starch mutant that may assist future research efforts to improve the yield and quality of grain and starch in rice through breeding.

[Content determination of twelve major components in Tibetan medicine Zuozhu Daxi by UPLC].

A quantitative analytical method of ultra-high performance liquid chromatography (UPLC) was developed for simultaneously determining twelve components in Tibetan medicine Zuozhu Daxi. SIMPCA 12.0 software was used a principal component analysis PCA) and partial small squares analysis (PLSD-DA) on the twelve components in 10 batches from four pharmaceutical factories. Acquity UPLC BEH C15 column (2.1 mm x 100 mm, 1.7 µm) was adopted at the column temperature of 35 °C and eluted with acetonitrile (A) -0.05% phosphate acid solution (B) as the mobile phase with a flow rate of 0. 3 mL · min(-1). The injection volume was 1 µL. The detection wavelengths were set at 210 nm for alantolactone, isoalantolactone and oleanolic; 260 nm for trychnine and brucine; 288 nm for protopine; 306 nm for protopine, resveratrol and piperine; 370 nm for quercetin and isorhamnetin. The results showed a good separation among index components, with a good linearity relationship (R2 = 0.999 6) within the selected concentration range. The average sample recovery rates ranged between 99.44%-101.8%, with RSD between 0.37%-1.7%, indicating the method is rapid and accurate with a good repeatability and stability. The PCA and PLSD-DA analysis on the sample determination results revealed a great difference among samples from different pharmaceutical factories. The twelve components included in this study contributed significantly to the quantitative determination of intrinsic quality of Zuozhu Daxi. The UPLC established for to the quantitative determination of the twelve components can provide scientific basis for the comprehensive quality evaluation of Zuozhu Daxi.

Comparative proteomic analysis of early salt stress responsive proteins in roots and leaves of rice.

Growth and productivity of rice (Oryza sativa L.) are severely affected by salinity. Understanding the mechanisms that protect rice and other important cereal crops from salt stress will help in the development of salt-stress-tolerant strains. In this study, rice seedlings of the same genetic species with various salt tolerances were studied. We first used 2DE to resolve the expressed proteome in rice roots and leaves and then used nanospray liquid chromatography/tandem mass spectrometry to identify the differentially expressed proteins in rice seedlings after salt treatment. The 2DE assays revealed that there were 104 differentially expressed protein spots in rice roots and 59 in leaves. Then, we identified 83 proteins in rice roots and 61 proteins in rice leaves by MS analysis. Functional classification analysis revealed that the differentially expressed proteins from roots could be classified into 18 functional categories while those from leaves could be classified into 11 functional categories. The proteins from rice seedlings that most significantly contributed to a protective effect against increased salinity were cysteine synthase, adenosine triphosphate synthase, quercetin 3-O-methyltransferase 1, and lipoxygenase 2. Further analysis demonstrated that the primary mechanisms underlying the ability of rice seedlings to tolerate salt stress were glycolysis, purine metabolism, and photosynthesis. Thus, we suggest that differentially expressed proteins may serve as marker group for the salt tolerance of rice.

A polarizable dipole-dipole interaction model for evaluation of the interaction energies for N-H···O=C and C-H···O=C hydrogen-bonded complexes.

In this article, a polarizable dipole-dipole interaction model is established to estimate the equilibrium hydrogen bond distances and the interaction energies for hydrogen-bonded complexes containing peptide amides and nucleic acid bases. We regard the chemical bonds N-H, C=O, and C-H as bond dipoles. The magnitude of the bond dipole moment varies according to its environment. We apply this polarizable dipole-dipole interaction model to a series of hydrogen-bonded complexes containing the N-H···O=C and C-H···O=C hydrogen bonds, such as simple amide-amide dimers, base-base dimers, peptide-base dimers, and ß-sheet models. We find that a simple two-term function, only containing the permanent dipole-dipole interactions and the van der Waals interactions, can produce the equilibrium hydrogen bond distances compared favorably with those produced by the MP2/6-31G(d) method, whereas the high-quality counterpoise-corrected (CP-corrected) MP2/aug-cc-pVTZ interaction energies for the hydrogen-bonded complexes can be well-reproduced by a four-term function which involves the permanent dipole-dipole interactions, the van der Waals interactions, the polarization contributions, and a corrected term. Based on the calculation results obtained from this polarizable dipole-dipole interaction model, the natures of the hydrogen bonding interactions in these hydrogen-bonded complexes are further discussed.

Iron-Catalyzed Aminoalkylative Carbonylative Cyclization of Alkenes toward α-Tetralones.

Carbonylative multifunctionalization of alkenes is an efficient approach to introduce multiple functional groups into one molecule from easily available materials. Herein, we developed an iron-catalyzed radical relay carbonylative cyclization of alkenes with acetamides. Various α-tetralones can be constructed in moderate yields from readily available substrates with an earth-abundant iron salt as the catalyst.

Direct C-H Sulfuration: Synthesis of Disulfides, Dithiocarbamates, Xanthates, Thiocarbamates and Thiocarbonates.

In light of the important biological activities and widespread applications of organic disulfides, dithiocarbamates, xanthates, thiocarbamates and thiocarbonates, the continual persuit of efficient methods for their synthesis remains crucial. Traditionally, the preparation of such compounds heavily relied on intricate multi-step syntheses and the use of highly prefunctionalized starting materials. Over the past two decades, the direct sulfuration of C-H bonds has evolved into a straightforward, atom- and step-economical method for the preparation of organosulfur compounds. This review aims to provide an up-to-date discussion on direct C-H disulfuration, dithiocarbamation, xanthylation, thiocarbamation and thiocarbonation, with a special focus on describing scopes and mechanistic aspects. Moreover, the synthetic limitations and applications of some of these methodologies, along with the key unsolved challenges to be addressed in the future are also discussed. The majority of examples covered in this review are accomplished via metal-free, photochemical or electrochemical approaches, which are in alignment with the overraching objectives of green and sustainable chemistry. This comprehensive review aims to consolidate recent advancements, providing valuable insights into the dynamic landscape of efficient and sustainable synthetic strategies for these crucial classes of organosulfur compounds.

Bioinspired Bottlebrush Polymers Effectively Alleviate Frictional Damage Both In Vitro and In Vivo.

Bottlebrush polymers (BB) have emerged as compelling candidates for biosystems to face tribological challenges, including friction and wear. This study provides a comprehensive assessment of an engineered triblock BB polymer's affinity, cell toxicity, lubrication, and wear protection in both in vitro and in vivo settings, focusing on applications for conditions like osteoarthritis and dry eye syndrome. Results show that the designed polymer rapidly adheres to various surfaces (e.g., cartilage, eye, and contact lens), forming a robust, biocompatible layer for surface lubrication and protection. The tribological performance and biocompatibility are further enhanced in the presence of hyaluronic acid (HA) both in vitro and in vivo. The exceptional lubrication performance and favorable interaction with HA position the synthesized triblock polymer as a promising candidate for innovative treatments addressing deficiencies in bio-lubricant systems.