Gold Nanorod Amalgamation: Machine Learning Empowered Discrimination of Biothiol and Thiol Ratios.

Biothiols, characterized by thiol groups, exhibit remarkable affinity for certain metals, playing pivotal roles in intracellular and extracellular biological processes. Fluctuations in their levels profoundly impact overall physiological health. Despite the development of various probes for biothiol detection and quantification, their inability to monitor thiol-to-disulfide state transitions persists as a limitation. Given their association with pathologies, early detection remains imperative. Gold nanorod (AuNR)-based colorimetric probes have garnered attention for their utility in visual diagnostic assays. Herein, we present a cost-effective, and sensitive multicolor ratio measuring probe enabling on-site simultaneous identification, discrimination, and quantification of essential biothiols─cysteine (CYS), glutathione (GSH), cystine (CYSS), and glutathione disulfide (GSSG)─while also quantifying thiol-to-disulfide ratios. Our investigation clarifies the probe's functionality, elucidating etching and antietching mechanisms based on sulfhydryl group coordination with Hg2+. This coordination impedes gold amalgam formation, facilitating discriminative detection via AuNR size and aspect ratio modulation, validated by transmission electron microscopy. Notably, distinct rainbow-like fingerprint patterns were discernible both visually and spectroscopically for the aforementioned biothiols and their respective thiol-to-disulfide ratios. Subsequent qualitative and quantitative analyses via linear discriminant analysis (LDA) and partial least squares regression revealed linear correlations over broad concentration ranges (CYS: 1.9-40 µmol L-1, GSH: 3.2-200.0 µmol L-1, CYSS: 2.0-70.0 µmol L-1, GSSG: 3.7-100.0 µmol L-1), with detection limits of 0.66 µmol L-1 (CYS), 1.07 µmol L-1 (GSH), 0.69 µmol L-1 (CYSS), and 1.24 µmol L-1 (GSSG). Moreover, thiol-to-disulfide ratios exhibited linear patterns within 0.2-5 µmol L-1, with detection limits of 0.13 and 0.09 µmol L-1, and exceptional analytical sensitivities of 32.648 and 49.782 for (CYS/CYSS) and (GSH/GSSG), respectively. Lastly, we evaluated the probe's performance in complex matrices relative to aqueous media, both quantitatively and qualitatively.

Thiamine disulfide derivatives in thiol redox regulation: Role of thioredoxin and glutathione systems.

Thiamine (vitamin B1), under the proper conditions, is able to reversibly open the thiazole ring, forming a thiol-bearing molecule that can be further oxidized to the corresponding disulfide. To improve the bioavailability of the vitamin, several derivatives of thiamine in the thioester or disulfide form were developed and extensively studied over time, as apparent from the literature. We have examined three thiamine-derived disulfides: thiamine disulfide, sulbutiamine, and fursultiamine with reference to their intervention in modulating the thiol redox state. First, we observed that both glutathione and thioredoxin (Trx) systems were able to reduce the three disulfides. In particular, thioredoxin reductase (TrxR) reduced these disulfides either directly or in the presence of Trx. In Caco-2 cells, the thiamine disulfide derivatives did not modify the total thiol content, which, however, was significantly decreased by the concomitant inhibition of TrxR. When oxidative stress was induced by tert-butyl hydroperoxide, the thiamine disulfides exerted a protective effect, indicating that the thiol form deriving from the reduction of the disulfides might be the active species. Further, the thiamine disulfides examined were shown to increase the nuclear levels of the transcription factor nuclear factor erythroid 2 related factor 2 and to stimulate both expression and activity of NAD(P)H quinone dehydrogenase 1 and TrxR. However, other enzymes of the glutathione and Trx systems were scarcely affected. As the thiol redox balance plays a critical role in oxidative stress and inflammation, the information presented can be of interest for further research, considering the potential favorable effect exerted in the cell by many sulfur compounds, including the thiamine-derived disulfides.

Efficient Polycrystalline Single-Cation Perovskite Light-Emitting Diodes by Simultaneous Intracrystal and Interfacial Defect Passivation.

Polycrystalline perovskite light-emitting diodes (PeLEDs) have shown great promise with high efficiency and easy processability. However, PeLEDs using single-cation polycrystalline perovskite emitters have demonstrated low efficiency due to defects within the grains and at the interfaces between the perovskite layer and the charge injection contact. Thus, simultaneous defect engineering of perovskites to suppress exciton loss within the grains and at the interfaces is crucial for achieving high efficiency in PeLEDs. Here, 1,8-octanedithiol which is a strong nucleophile, is used to increase the luminescence efficiency of a single-cation perovskite by suppressing non-radiative recombination within the grains of their polycrystalline emitter film as well as at their interface with an anode. The dithiol additive performs a multifunctional role in defect passivation, spatial confinement of excitons, and prevention of exciton quenching at the interface between the perovskite layer and the underlying hole-injection layer. Photoluminescence studies demonstrate that incorporating the dithiol additive significantly enhances the charge carrier dynamics in perovskites, resulting in an external quantum efficiency (EQE) of up to 23.46% even in a simplified PeLED that does not use a hole-injection layer. This represents the highest level of EQE achieved among devices utilizing polycrystalline single-cation perovskites.

A novel role for thioredoxin-related transmembrane protein TMX4 in platelet activation and thrombus formation.

BACKGROUND: The functions of critical platelet proteins are controlled by thiol-disulfide exchanges, which are mediated by the protein disulfide isomerase (PDI) family. It has been shown that some PDI family members are important in platelet activation and thrombosis with distinct functions. TMX4, a membrane-type PDI family member, is expressed in platelets, whether it has a role in platelet activation remains unknown. OBJECTIVES: To determine the role of TMX4 in platelet activation and thrombosis. METHODS: The phenotypes of TMX4-deficient mice were evaluated in tail bleeding time assay and laser-induced and FeCl3-induced arterial injury models. The functions of TMX4 in platelets were assessed in vitro using TMX4-null platelets, recombinant TMX4 protein and anti-TMX4 antibody. RESULTS: Compared with the control mice, Tie2-Cre/TMX4fl/fl mice deficient of hematopoietic and endothelial TMX4 exhibited prolonged tail bleeding times and reduced platelet thrombus formation. Pf4-Cre/TMX4fl/fl mice deficient of platelet TMX4 also had prolonged tail bleeding times and decreased thrombus formation, which was rescued by injection of recombinant TMX4 protein. Consistently, TMX4 deficiency inhibited platelet aggregation, integrin αIIbß3 activation, P-selectin expression, phosphatidylserine exposure and thrombin generation, without affecting tyrosine phosphorylation of intracellular signaling molecules Syk, LAT and PLCγ2 and calcium mobilization. Recombinant TMX4 protein enhanced platelet aggregation and reduced integrin αIIbß3 disulfide bond, and TMX4 deficiency decreased free thiols of integrin αIIbß3, consistent with a potent reductase activity of TMX4. In contrast, an inactive TMX4 protein and a specific anti-TMX4 antibody inhibited platelet aggregation. CONCLUSIONS: TMX4 is a novel PDI family member that enhances platelet activation and thrombosis.

Unveiling the mechanism of cysteamine dioxygenase: A combined HPLC-MS assay and metal-substitution approach.

Mammalian cysteamine dioxygenase (ADO), a mononuclear non-heme Fe(II) enzyme with three histidine ligands, plays a key role in cysteamine catabolism and regulation of the N-degron signaling pathway. Despite its importance, the catalytic mechanism of ADO remains elusive. Here, we describe an HPLC-MS assay for characterizing thiol dioxygenase catalytic activities and a metal-substitution approach for mechanistic investigation using human ADO as a model. Two proposed mechanisms for ADO differ in oxygen activation: one involving a high-valent ferryl-oxo intermediate. We hypothesized that substituting iron with a metal that has a disfavored tendency to form high-valent states would discriminate between mechanisms. This chapter details the expression, purification, preparation, and characterization of cobalt-substituted ADO. The new HPLC-MS assay precisely measures enzymatic activity, revealing retained reactivity in the cobalt-substituted enzyme. The results obtained favor the concurrent dioxygen transfer mechanism in ADO. This combined approach provides a powerful tool for studying other non-heme iron thiol oxidizing enzymes.

Improvement of fluorescence properties by surface modification of CdS-ZnS quantum dots by thiol compounds and its application as a sensitive fluorescence probe for copper ion detection.

The capped CdS-ZnS quantum dots (QDs) were synthesized with various thiol capping agents of glycolic acid (TGA), mercaptosuccinic acid (MSA), and L-cysteine (LCY) and used as fluorescence probe for determination of Cu (II) ions. The method of two-level three-factor full-factorial experiment design was used to achieve the best optical fluorescence emission. Results revealed that Cu (II) ions can effectively quench the emission of QDs, and the fluorescence intensity is linearly decreased with increasing Cu (II) ion concentration. The limit of detection for CdS-ZnS@ QDs capped with TGA, MSA, and LCY was obtained at 1.15 × 10-7, 1.32 × 10-7, and 2.19 × 10-7 mol L-1, respectively, with linear dynamic range of 3.13 × 10-6 to 1.41 × 10-4 mol L-1. Luminescence quantum yields of CdS-ZnS@LCY, CdS-ZnS@MSA, and CdS-ZnS@TGA were obtained at 4.17, 1.92, and 2.47, respectively. Results indicated that no significant quenching occurred in the presence of the other metal ions. The binding constant (Kb) of capped CdS-ZnS@ QDs with Cu2+ and the other metal ions was also investigated and discussed. The Kb value for Cu2+ was obtained considerably more than that the other ions. This work presents a new and sensitive method for determination of Cu2+ ion.

Wormhole Mesoporous Silica Framework with Enhanced Thiol Loading for Improved Hg²âº Sequestration.

Thiol-functionalized mesoporous silica and materials potentially dedicated to diverse applications of composite materials, metal colloids, and metal catalysts, etc. Here, we developed a new synthesis route for 3-methacryloxypropyl trimethoxy silane (MPTMS) functionalized mesoporous silica (KIT-6), achieving a 71.5% enhancement in thiol functionalization on KIT-6 surfaces. Characterization using XRD, TEM, BET, FTIR, Raman, 29Si NMR, XPS, and ICP-OES revealed structural and morphological features. XRD, TEM, and BET confirmed the three-dimensional structural stabilization of mesoporous silica with ~4 nm pore diameter and a surface area of 1451 m2 g-1. FTIR, Raman, and 29Si NMR studies established the mechanism of thiol functionalization, the formation of a new wormhole chain structural framework (WCSF), and stabilization through hydrogen bonding within the mesopores. The 29Si NMR spectra showed characteristic peaks (T3, T2, Q4, Q3) indicating self-condensed functionalized thiols with siloxane networks. XPS analysis validated enhanced thiol functionalization, indicating a structurally homogeneous WCSF suitable for mercury adsorption. ICP-OES measured a mercury adsorption capacity of 3199.6 mg g-1 for KIT-6, with an Hg2+/S ratio of 1.8, corroborated by molecular structure and mechanism analysis. This innovative thiol functionalization approach enhances the efficacy of applications such as extracting Hg2+ from contaminated sources.

Athyrium yokoscense, a cadmium-hypertolerant fern, exhibits two cadmium stress mitigation strategies in its roots and aerial parts.

Athyrium yokoscense is hypertolerant to cadmium (Cd) and can grow normally under a high Cd concentration despite Cd being a highly toxic heavy metal. To mitigate Cd stress in general plant species, Cd is promptly chelated with a thiol compound and is isolated into vacuoles. Generated active oxygen species (ROS) in the cytoplasm are removed by reduced glutathione. However, we found many differences in the countermeasures in A. yokoscense. Thiol compounds accumulated in the stele of the roots, although a long-term Cd exposure induced Cd accumulation in the aerial parts. Synchrotron radiation-based X-ray fluorescence (SR-XRF) analysis indicated that a large amount of Cd was localized in the cell walls of the roots. Overexpression of AyNramp5a, encoding a representative Fe and Mn transporter of A. yokoscense, increased both Cd uptake and Fe and Mn uptake in rice calli under the Cd exposure conditions. Organic acids are known to play a key role in reducing Cd availability to the plants by forming chelation and preventing its entry in free form into the roots. In A. yokoscense roots, Organic acids were abundantly detected. Investigating the chemical forms of the Cd molecules by X-ray absorption fine structure (XAFS) analysis detected many compounds with Cd-oxygen (Cd-O) binding in A. yokoscense roots, whereas in the aerial parts, the ratio of the compounds with Cd-sulfur (Cd-S) binding was increased. Together, our results imply that the strong Cd tolerance of A. yokoscense is an attribute of the following two mechanisms: Cd-O compound formation in the cell wall is a barrier to reduce Cd uptake into aerial parts. Thiol compounds in the region of root stele are involved in detoxication of Cd by formation of Cd-S compounds.

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.

Cyclic Acetals as Expanding Monomers to Reduce Shrinkage.

Polarity-reversal catalysts (PRCs) for hydrogen-atom transfer reactions have been known in radical chemistry for more than 60 years but are rarely described and utilized in the field of photopolymerization up to now. Herein, we present the use of thiols in a unique dual function as thiol-ene click reagents and as polarity-reversal catalyst (PRC) for the radical-mediated redox rearrangements of benzylidene acetals. During the rearrangement reaction, cyclic benzylidene acetals are transformed into benzoate esters leading to a significant volumetric expansion to reduce thermoset shrinkage. We were able to show that this expansion on a molecular level reduces shrinkage and polymerization stress but does not significantly affect the (thermo-)mechanical properties of the cross-linked networks. One of the key advantages of this process lies in its simplicity. No additives like sensitizers or combinations of different initiators (radical and cationic) are needed. Furthermore, the same light source can be used for both the polymerization reaction and expansion through rearrangement. Additionally, the applied photoinitiator enables spatial and temporal control of the polymerization; thus, the developed system can be an excellent platform for additive manufacturing processes.

Versatile and efficient protein association through chemically modified Sphingomyelin Nanosystems (SNs) for enhanced delivery.

Proteins are biological macromolecules well known to regulate many cellular signaling mechanisms. For instance, they are very appealing for their application as therapeutic agents, presenting high specificity and activity. Nonetheless, they suffer from unfolding, instability and low bioavailability making their administration through systemic and other routes very tough. To overcome these drawbacks, drug delivery systems and nanotechnology have arisen to deliver biomolecules in a sustained manner while, at the same time, increasing dose availability, protecting the cargo without compromising proteins' bioactivity, and enhancing intracellular delivery. In this work, we proposed the optimization of sphingomyelin nanosystems (SNs) for the delivery of a wide collection of proteins (ranging from 10-500 kDa and pI) using diverse chemical association strategies. We have further characterized SNs by varied analytical methodologies. We have also carried out in vitro experiments to validate the potential of the developed formulations. As the final goal, we aim to obtain evidence of the potential use of SNs for the development of protein therapeutics.

Efficient unsymmetric disulfide formation by molecular-scale tailoring of ortho-polyquinone-based polymer photocatalyst.

Disulfide bonds, especially unsymmetric disulfide bonds, have important applications in bioactivity and drug molecules, but the synthesis of unsymmetric disulfide bonds remains challenging due to efficiency and selectivity issues. Herein, this work utilizes anthraquinone (AQ) and cyclictriphosphonononitrile through a nucleophilic substitution reaction to synthesize an organic polymer (ANTH-AMI) that incorporates an ortho-polyquinone (o-polyquinone) redox center. The anthraquinone molecule functions as a redox center, capable of accepting photoinduced electrons and subsequently transferring them to initiate an electron-coupled hydrogenation reaction (AQ to AQH). Moreover, the proximity of the o-polyquinone redox sites facilitates the catalysis of unsymmetric disulfide bond formation. Consequently, the ANTH-AMI photocatalysts demonstrate exceptional yields (up to 82 %), substrate versatility, cycling stability, and scalable preparation in promoting unsymmetric coupling reactions of thiol. This work offers a solution for designing organic polymer photocatalysts with adjacent multiple redox centers for cross-coupling reactions.

Transmembrane thiol isomerase TMX1 counterbalances the effect of ERp46 to inhibit platelet activation and integrin αIIbß3 function.

Background: Previous studies have shown that thiol isomerases such as ERp46 positively regulate platelet function by reducing integrin αIIbß3 disulfides, and the transmembrane thiol isomerase TMX1 negatively regulates integrin αIIbß3 activation. However, whether and how the positive and negative thiol isomerases interact with each other and their interactions participate in platelet activation remain unknown. Objectives: To investigate whether and how TMX1 regulates the effect of ERp46 on platelet function. Methods: Using ERp46- and TMX1-deficient platelets, anti-TMX1 antibody, and wild-type TMX1 (TMX1-CPAC, TMX1-SS) and inactive TMX1 (TMX1-SPAS, TMX1-OO) proteins, we studied the antagonistic effect of TMX1 on ERp46 in platelet aggregation, clot retraction, and integrin αIIbß3 signaling. The underlying mechanisms were further determined using thiol labeling, reductase activity, and other assays. Results: Anti-TMX1 antibody and TMX1-OO reversed the decreased aggregation of ERp46-deficient platelets induced by thrombin, convulxin, and U46619. Anti-TMX1 antibody reversed the attenuated integrin αIIbß3 function of ERp46-deficient platelets. TMX1 inhibited ERp46 reductase activity in a concentration-dependent manner. TMX1 oxidized thiols of ERp46 and those of integrin αIIbß3 generated by ERp46. Moreover, TMX1 deficiency increased free thiols of ERp46 in platelets, which was reversed by the addition of wild-type TMX1 protein. Besides, anti-TMX1 antibody increased free thiols of ERp46 in wild-type activated platelets. Conclusion: TMX1 not only oxidizes integrin αIIbß3 disulfides that are reduced by ERp46 but also directly oxidizes ERp46 to suppress its reduction of integrin αIIbß3. Thus, TMX1 is critical for maintaining platelets in a quiescent state and counterbalancing the effect of ERp46 to prevent platelet overactivation.

Deteriorated thiol-disulphide and oxidized-reduced glutathione status in blood in Alzheimer's disease.

BACKGROUND: Alzheimer's disease (AD) is a steadily advancing neurodegenerative condition, the occurrence and prevalence of which are on the rise in various populations. Suspected factors contributing to its development encompass the buildup of amyloid ß (Aß) plaques, the formation of neurofibrillary tangles induced by tau proteins, and heightened oxidative stress. In this study, we aimed to evaluate intra-cellular glutathione status and extracellular thiol-disulphide status in patients with AD. METHODS: Adult patients (>60 years old) diagnosed with AD based on DSM-IV diagnostic criteria were included in the study. Patients were divided into 3 groups as mild, moderate and severe according to Mini Mental Status Examination (MMSE) and clinical findings. Extracellular thiol-disulfide and intracellular oxidized-reduced glutathione status parameters for patient and control groups were analyzed before and after reduction procedures by using reaction of thiol groups with DTNB. RESULTS: The reduced forms of both balances (native thiol (NT) and reduced glutathione (GSH)) were significantly lower in the patient group than the control group (p = 0.031 and <0.001, respectively), while oxidized forms (disulphide (SS) and oxidized glutathione (GSSG)) and SS/NT and GSSG/GSH percent ratios were significantly higher (p < 0.05 for all). The disease duration and oxidative stress were significantly higher in the severe group of AD. There was a shift in intracellular and extracellular thiol balances towards the oxidized side, along with correlations between MMSE and these balances (rho = -0.412 for SS/NT and rho = -0.488 for GSSG/GSH), with GSSG/GSH identified as a significant predictive factor (odds ratio (95 % confidence interval): 1.352 (1.136-1.610) for the moderate group and 1.829 (1.451-2.305) for the severe group. CONCLUSIONS: These findings suggest that blood redox balance is disrupted in AD.

Non-standard amino acid incorporation into thiol dioxygenases.

Thiol dioxygenases (TDOs) are non­heme Fe(II)­dependent enzymes that catalyze the O2-dependent oxidation of thiol substrates to their corresponding sulfinic acids. Six classes of TDOs have thus far been identified and two, cysteine dioxygenase (CDO) and cysteamine dioxygenase (ADO), are found in eukaryotes. All TDOs belong to the cupin superfamily of enzymes, which share a common ß­barrel fold and two cupin motifs: G(X)5HXH(X)3-6E(X)6G and G(X)5-7PXG(X)2H(X)3N. Crystal structures of TDOs revealed that these enzymes contain a relatively rare, neutral 3­His iron­binding facial triad. Despite this shared metal-binding site, TDOs vary greatly in their secondary coordination spheres. Site­directed mutagenesis has been used extensively to explore the impact of changes in secondary sphere residues on substrate specificity and enzymatic efficiency. This chapter summarizes site-directed mutagenesis studies of eukaryotic TDOs, focusing on the tools and practicality of non­standard amino acid incorporation.

Serum Thiols and Ischemia-Modified Albumin Levels in Children With Major Depressive Disorder: A Cross-Sectional Study.

Introduction This cross-sectional study aimed to investigate potential biomarkers of oxidative stress by analyzing serum thiol-disulfide homeostasis (TDH) and ischemia-modified albumin (IMA) levels in children who have been diagnosed with major depressive disorder (MDD). Methods The study included 24 medication-naive children aged seven to 17 years diagnosed with MDD and 19 healthy controls matched for age, gender, and body mass index. Clinical interviews were conducted using the Schedule for Affective Disorders and Schizophrenia for School-Age Children-Present and Lifetime Version (K-SADS-PL-DSM-5), and diagnoses were made according to DSM-5. The Child Depression Inventory (CDI) and the Clinical Global Impression Scale-Severity (CGI-S) were also administered to the participants. Venous blood samples were taken from all subjects to assess TDH and IMA levels, considered potential oxidative stress indicators. Results The study showed no significant difference in TDH and IMA levels between the MDD and the control groups. Although not statistically significant, it was observed that native thiol and total thiol levels were higher in the MDD group. No direct relationship was found between disease severity and either TDH or IMA levels. Conclusion In conclusion, while there were no significant differences in the levels of TDH and IMA, higher levels of both native and total thiols were found in the MDD group.

Enhanced mucoadhesive properties of ionically cross-linked thiolated gellan gum films.

Localized oral drug delivery offers several advantages for treating various disease conditions. However, drug retention at the disease site within the oral cavity is indeed a significant challenge due to the dynamic oral environment. The present study aimed to develop a mucoadhesive inner layer for a three-layer mucoadhesive bandage suitable for localized oral drug delivery. using gellan gum (GG) biopolymer. Gellan gum (GG) was modified using L-cysteine moieties via carbodiimide chemistry. Subsequently, gellan gum solution at different extents of thiolation was ionically cross-linked using aluminum ammonium sulfate. Thiolated gellan gum films of uniform thickness were prepared using a solvent casting method. The thickness of bare gellan gum film was 0.035 ± 0.0043 mm, whereas the thiolated gellan gum films, GG 1S and GG 2S showed a thickness of 0.0191 ± 0.0011 mm and 0.0188 ± 0.0004 mm respectively. A high work of adhesion was noted for thiolated gellan gum (GG 2S) with a value of 10 N.mm while using porcine buccal mucosa. An average tensile strength of 48.2 ± 2.46 MPa was measured for thiolated gellan gum films irrespective of the extent of thiolation. The high work of adhesion, favorable cytocompatibility, desirable mechanical properties, and free swell capacity in saline confirmed the suitability of ionically cross-linked thiolated gellan gum films as an inner mucoadhesive layer for the mucoadhesive bandage.

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.

Biomimetic conjugation inspired from pheomelanin via thiol-quinone addition for enzymatic functionalization of fibroin.

Fibroin has been extensively applied in the medicine, therapy, cosmetic, and food fields. Functional modification is a common route way to expand the application potential. Tyrosinase is versatile for enzymatic functionalization of fibroin by oxidizing tyrosine residues into dopaquinone. However, grafting of functional molecules to the protein-bound dopaquinone suffers from self-crosslinking due to competitive aryl coupling or addition with other nucleophile in protein. Herein, bioinspired from pheomelanin synthesis, a new approach with superior grafting efficiency and reaction rate for enzymatic grafting of protein was developed. The high reactivity of Michael addition between thiol and dopaquinone was utilized to promote the efficiency for grafting of PEG onto fibroin. The grafting of PEG with thiol group was superior to that with amine group. It demonstrated a superior efficacy for thiol group over amino group on enzymatic functionalization. This research firstly established an effective biomimetic approach for enzymatic functionalization of protein without the unexpected self-crosslinking. It could emerged to serve as the strategy of protein functionalization.

Deuteration Degree Controllable Synthesis of Aryl Deuteromethyl Ethers Through Dual photoredox and Thiol Catalysis.

Herein, we report a facile and efficient deuteration degree controllable method for the preparation of aryl deuteromethyl ethers through dual photoredox and thiol catalysis using phenols as the starting materials and inexpensive D2O and CDCl3 as the deuterium sources. All aryl d1, d2, and d3 deuteromethyl ethers can be precisely prepared with good to excellent yields and deuteration ratios. The reaction operates under mild conditions without the need for high temperatures or high loading of transition metal catalysts, and a wide range of functional groups are well tolerated.