Ultrathin organic polymer with p-πconjugated structure for simultaneous photocatalytic disulfide bond generation and CO_(2)reduction

Combining photocatalytic organic reactions with CO_(2)reduction is an efficient solar energy utilization mode,but it is still limited by the organic species that can be matched and the low conversion.Herein,ultrathin organic polymer with p-πconjugated structure(TPP)was rationally designed and prepared,and showed a high yield of CO(15.2 mmol g^(-1))and conversion of SAS coupled products(100%),far exceeding the organic polymer with P=O structure.The enhanced photoredox activity of TPP is ascribed to the orbital interaction between the p-orbital on phosphorus and theπ-orbitals of aromatic,which can accelerate the photoinduced charge carrier separation and improve the CO_(2)adsorption capacity.TPP can also be used for the dehydrocoupling of various benzyl mercaptans to the corresponding SAS bond products.This work provides a new concept for the efficient synthesis of disulfide bonds combined with CO_(2)reduction in a photoreaction system.

A Self-Healing and Nonflammable Cross-Linked Network Polymer Electrolyte with the Combination of Hydrogen Bonds and Dynamic Disulfide Bonds for Lithium Metal Batteries

The self-healing solid polymer electrolytes(SHSPEs)can spontaneously eliminate mechanical damages or micro-cracks generated during the assembly or operation of lithium-ion batteries(LIBs),significantly improving cycling performance and extending service life of LIBs.Here,we report a novel cross-linked network SHSPE(PDDP)containing hydrogen bonds and dynamic disulfide bonds with excellent self-healing properties and nonflammability.The combination of hydrogen bonding between urea groups and the metathesis reaction of dynamic disulfide bonds endows PDDP with rapid self-healing capacity at 28°C without external stimulation.Furthermore,the addition of 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide(EMIMTFSI)improves the ionic conductivity(1.13×10^(−4)S cm^(−1)at 28°C)and non-flammability of PDDP.The assembled Li/PDDP/LiFePO_(4)cell exhibits excellent cycling performance with a discharge capacity of 137 mA h g^(−1)after 300 cycles at 0.2 C.More importantly,the self-healed PDDP can recover almost the same ionic conductivity and cycling performance as the original PDDP.

Improving the Heat Resistance ofβ-1,4 Glucanase by Introducing Disulfide Bonds

Each possible pair of residues inβ-1,4 glucanase for disulfide formation was assessed using online websites,and four pairs L28C-S256C,Q41C-P278C,S122C-N163C and A184C-A215C were selected.Accordingly,four recombinant plasmids pET28a(+)EccslH28,pET28a(+)EccslH41,pET28a(+)EccslH122 and pET28a(+)EccslH184 were prepared and transformed into E.coli to express the recombinant enzymes.Then analysis on enzymatic properties showed that T50 of the recombinant enzymes was increased from 10 min for EccslHt2 to 90 min for EccslH28 and 40 min for EccslH41 at 70℃,while their optimum pH value and pH stability were not affected,which proved that the introduction of disulfide bond improved the thermal stability ofβ-1,4 glucanase.

Fine-tuning the activation behaviors of ternary modular cabazitaxel prodrugs for efficient and on-target oral anti-cancer therapy

The disulfide bond plays a crucial role in the design of anti-tumor prodrugs due to its exceptional tumor-specific redox responsiveness. However, premature breaking of disulfide bonds is triggered by small amounts of reducing substances (e.g., ascorbic acid, glutathione, uric acid and tea polyphenols) in the systemic circulation. This may lead to toxicity, particularly in oral prodrugs that require more frequent and high-dose treatments. Fine-tuning the activation kinetics of these prodrugs is a promising prospect for more efficient on-target cancer therapies. In this study, disulfide, steric disulfide, and ester bonds were used to bridge cabazitaxel (CTX) to an intestinal lymph vessel-directed triglyceride (TG) module. Then, synthetic prodrugs were efficiently incorporated into self-nanoemulsifying drug delivery system (corn oil and Maisine CC were used as the oil phase and Cremophor EL as the surfactant). All three prodrugs had excellent gastric stability and intestinal permeability. The oral bioavailability of the disulfide bond-based prodrugs (CTX-(C)S-(C)S-TG and CTX-S-S-TG) was 11.5- and 19.1-fold higher than that of the CTX solution, respectively, demonstrating good oral delivery efficiency. However, the excessive reduction sensitivity of the disulfide bond resulted in lower plasma stability and safety of CTX-S-S-TG than that of CTX-(C)S-(C)S-TG. Moreover, introducing steric hindrance into disulfide bonds could also modulate drug release and cytotoxicity, significantly improving the anti-tumor activity even compared to that of intravenous CTX solution at half dosage while minimizing off-target adverse effects. Our findings provide insights into the design and fine-tuning of different disulfide bond-based linkers, which may help identify oral prodrugs with more potent therapeutic efficacy and safety for cancer therapy.

Synthesis of nucleoside-peptide conjugate with disulfide bond as linker at C-5 of uridine

In order to prepare pyrimidine nucleoside-peptide conjugate concisely, we developed a one-pot synthetic strategy. Started from uridine, 5-S-acetyl-thiomethyl-2＇,3 ＇-di-O-isopropylidene-uridine （4） was synthesized as the key intermediate in four steps. Under acidic condition, compound 4 was deprotected and reacted with PySS-R （8, 12, 15, Py = 2-pyridyl, R = amino acid or peptide） in one pot to form uridine conjugates （9, 13, 2） with disulfide bond as linker.

Investigating the crucial roles of aliphatic tails in disulfide bond-linked docetaxel prodrug nanoassemblies

Disulfide bond-bridging strategy has been extensively utilized to construct tumor specificity-responsive aliphatic prodrug nanoparticles(PNPs) for precise cancer therapy. Yet, there is no research shedding light on the impacts of the saturation and cis-trans configuration of aliphatic tails on the self-assembly capacity of disulfide bond-linked prodrugs and the in vivo delivery fate of PNPs. Herein, five disulfide bond-linked docetaxelfatty acid prodrugs are designed and synthesized by using stearic acid, elaidic acid, oleic acid, linoleic acid and linolenic acid as the aliphatic tails, respectively. Interestingly, the cistrans configuration of aliphatic tails significantly influences the self-assembly features of prodrugs, and elaidic acid-linked prodrug with a trans double bond show poor self-assembly capacity. Although the aliphatic tails have almost no effect on the redox-sensitive drug release and cytotoxicity, different aliphatic tails significantly influence the chemical stability of prodrugs and the colloidal stability of PNPs, thus affecting the in vivo pharmacokinetics, biodistribution and antitumor efficacy of PNPs. Our findings illustrate how aliphatic tails affect the assembly characteristic of disulfide bond-linked aliphatic prodrugs and the in vivo delivery fate of PNPs, and thus provide theoretical basis for future development of disulfide bond-bridged aliphatic prodrugs.

Oxidation-strengthened disulfide-bridged prodrug nanoplatforms with cascade facilitated drug release for synergetic photochemotherapy

One of the major barriers in utilizing prodrug nanocarriers for cancer therapy is the slow release of parent drug in tumors.Tumor cells generally display the higher oxidative level than normal cells,and also displayed the heterogeneity in terms of redox homeostasis level.We previously found that the disulfide bond-linkage demonstrates surprising oxidationsensitivity to form the hydrophilic sulfoxide and sulphone groups.Herein,we develop oxidation-strengthened prodrug nanosystem loaded with pyropheophorbide a(PPa)to achieve light-activatable cascade drug release and enhance therapeutic efficacy.The disulfide bond-driven prodrug nanosystems not only respond to the redox-heterogeneity in tumor,but also respond to the exogenous oxidant(singlet oxygen)elicited by photosensitizers.Once the prodrug nanoparticles(NPs)are activated under irradiation,they would undergo an oxidative self-strengthened process,resulting in a facilitated drug cascade release.The IC50 value of the PPa@PTX-S-S NPs without irradiation was 2-fold higher than those of NPs plus irradiation.In vivo,the PPa@PTX prodrug NPs display prolonged systemic circulation and increased accumulation in tumor site.The PPa@PTXS-S NPs showed much higher efficiency than free PTX or the PPa@PTX-C-C NPs to suppress the growth of 4 T1 tumors.Therefore,this novel oxidation-strengthened disulfide-bridged prodrug-nanosystem has a great potential in the enhanced efficacy of cancer synergetic photochemotherapy.

Solubility of disulfide-bonded proteins in the cytoplasm of Escherichia co/i and its “oxidizing” mutant

AIM: To study the influence of redox environment of Escherichia coli (E(?) coli) cytoplasm on disulfide bond formation of recombinant proteins. METHODS: Bovine fibrobllast growth factor (BbFGF) was selected as a model of simple proteins with a single disulfide bond and free cysteines. Anti-HBsAg single-chain Fv (HBscFv), an artificial multidomain protein, was selected as the model molecule of complex protein with 2 disulfide bonds. A BbFGF-producing plasmid, pJN-BbFGF, and a HBscFv producing-plasmid, pQE-HBscFv, were constructed and transformed into E(?)coli strains BL21(DE3) and M15[pREP4] respectively. At the same time, both plasmids were transformed into a reductase-deficient host strain,E(?)coli Origami(DE3). The 4 recombinant E(?)coli strains were cultured and the target proteins were purified. Solubility and bioactivity of recombinant BbFGF and HBscFv produced in different host strains were analyzed and compared respectively. RESULTS: All recombinant E(?)coli strains could efficiently produce target proteins. The level of BbFGF in BL21(DE3) was 15-23% of the total protein, and was 5-10% in Origami (DE3). In addition, 65% of the BbFGF produced in BL21(DE3) formed into inclusion body in the cytoplasm, and all the target proteins became soluble in Origami (DE3). The bioactivity of BbFGF purified from Origami(DE3) was higher than its counterpart from BL21(DE3). The ED50 of BbFGF from Origami(DE3) and BL21(DE3) was 1.6 μg/L and 2.2 μg/L, respectively. Both HBscFv formed into inclusion body in the cytoplasm of M15[pQE-HBscFv] or Origami[pQE-HBscFv]. But the supernatant of Origami [pQE-HBscFv] lysate displayed weak bioactivity and its counterpart from M15[pQE-HBscFv] did not display any bioactivity. The soluble HBscFv in Origami[pQE-HBscFv] was purified to be 1-2 mg/L and its affinity constant was determined to be 2.62×107 mol/L. The yield of native HBscFv refolded from inclusion body in M15[pQE-HBscFv] was 30-35 mg/L and the affinity constant was 1.98×107 mol/L. There was no significant difference between the bioactivity of HBscFvs refolded from the inclusion bodies produced in different host strains. CONCLUSION: Modification of the redox environment of E(?)coli cytoplasm can significantly improve the folding of recombinant disulfide-bonded proteins produced in it.

In Silico Disulfide Bond Engineering to Improve Human LEPTIN Stability

Enhancing the stability of biomolecules is one of the hot topics in industry.In this study,we enhanced the stability of an important protein called LEPTIN.LEPTIN is a hormone secreted by fat cells playing an essential role in body weight and composition,and its deficiency can result in several disorders.The treatment of related LEPTIN dysfunctions is often available in the form of injection.To decrease the cost and the frequency of its applications can be achieved by increasing its lifetime through engineering LEPTIN.In this study,to engineer LEPTIN,we have introduced disulfide bonds.Disulfide By Design server was used to predict the suitable nominate pairs,which suggested three pairs of amino acids to be mutated to cysteine for disulfide bond formation.Additionally,to further evaluate the effect of combined mutations,we combined these three nominated pairs to produce three more mutants.In order to assess the effect of introduced mutations,molecular dynamic(MD)simulation was performed.The result suggests that Mutant-1 is more stable in comparison to wild-type and the other mutants.Moreover,docking results showed that the introduced mutation does not affect the receptor binding performance;therefore,it can be considered a suitable choice for future protein engineering.

A Prediction Method of Protein Disulfide Bond Based on Hybrid Strategy

A prediction method of protein disulfide bond based on support vector machine and sample selection is proposed in this paper. First, the protein sequences selected are en-coded according to a certain encoding, input data for the prediction model of protein disulfide bond is generated;Then sample selection technique is used to select a portion of input data as training samples of support vector machine;finally the prediction model training samples trained is used to predict protein disulfide bond. The result of simulation experiment shows that the prediction model based on support vector ma-chine and sample selection can increase the prediction accuracy of protein disulfide bond.

A Disulfide-Based Poly(ether-b-amide)Copolymer with Rapid Self-healing Ability under Moderate Conditions

Comprehensive Summary A disulfide-based poly(ether-b-amide)copolymer with rapid self-healing capability under moderate conditions was synthesized from 4,4’-dithiodibutyric acid(DTDBA),isophorondiamine(IPDA)and poly(tetramethylene oxide)(PTMO)based on a two-step method.The incorporation of IPDA with asymmetric structure and substantial steric hindrance not only effectively decreased the number of regular H-bonds,but also inhibited the crystallization of polyamide segments,imparting the synthesized poly(ether-b-amide)copolymer with an amorphous structural feature.Based on the coordination of segmental diffusion and recombination of disulfide bonds and hydrogen bonds,the scratches and damaged mechanical properties of PEBADS-I611 could be completely self-healed after healing at 40°C for only 11 min and 3 h,respectively.

Transfer of disulfide bond formation modules via yeast artificial chromosomes promotes the expression of heterologous proteins in Kluyveromyces marxianus

Kluyveromyces marxianus is a food-safe yeast with great potential for producing heterologous proteins.Improving the yield in K.marxianus remains a challenge and incorporating large-scale functional modules poses a technical obstacle in engineering.To address these issues,linear and circular yeast artificial chromosomes of K.marxianus(KmYACs)were constructed and loaded with disulfide bond formation modules from Pichia pastoris or K.marxianus.These modules contained up to seven genes with a maximum size of 15 kb.KmYACs carried telomeres either from K.marxianus or Tetrahymena.KmYACs were transferred successfully into K.marxianus and stably propagated without affecting the normal growth of the host,regardless of the type of telomeres and configurations of KmYACs.KmYACs increased the overall expression levels of disulfide bond formation genes and significantly enhanced the yield of various heterologous proteins.In high-density fermentation,the use of KmYACs resulted in a glucoamylase yield of 16.8 g/l,the highest reported level to date in K.marxianus.Transcriptomic and metabolomic analysis of cells containing KmYACs suggested increased flavin adenine dinucleotide biosynthesis,enhanced flux entering the tricarboxylic acid cycle,and a preferred demand for lysine and arginine as features of cells overexpressing heterologous proteins.Consistently,supplementing lysine or arginine further improved the yield.Therefore,KmYAC provides a powerful platform for manipulating large modules with enormous potential for industrial applications and fundamental research.Transferring the disulfide bond formation module via YACs proves to be an efficient strategy for improving the yield of heterologous proteins,and this strategy may be applied to optimize other microbial cell factories.

重组人纽兰格林一级结构确证与二硫键分析

Neuregulin plays an important role in heart structure and function.Research discovered that recombinant neuregulin could reduce the degree of damage on myocardial cells caused by ischemia,hypoxia and viral infection.The primary structure,including N-terminal sequence,C-terminal sequence,PMF,accurate molecular mass,and disulfide bonding pattern of recombinant human neuregulin,have been identified by ESI-Q-TOF MS,Autoflex MALDI-TOF MS,9.4T Apex Q-FT MS and Ultraflex Ⅲ MALDI-TOF/TOF combining with two e]ymatic digestion.A abnormal peptide impurity in this drug was found and sequenced by Q-TOF MS and TOF/TOF MS,this is useful for the product quanlity control.

A description of alkaline phosphatases from marine organisms

Alkaline phosphatases(APs) are non-specifi c phosphohydrolases, and they are widely used in clinical diagnostics and biological studies. APs are widespread in nature and exhibit dif ferent structural formulations. Based on the diversity of biogenetic sources, APs exhibit temperature-propensity traits, and they are classifi ed as psychrophilic, mesophilic, and thermophilic. In this article, the characteristics of psychrophilic APs from marine organisms were described, accompanied by a simple description of APs from other organisms. This review will facilitate better utilization of marine APs in the biotechnology fi eld.

Optimization of DsbA Purification from Recombinant Escherichia coli Broth Using Box-Behnken Design Methodolog

Disulfide bond formation protein A （DsbA） is one of the important helper proteins for folding in protein synthesis in vivo. In this study, purification of recombinant DsbA was investigated by examining four important factors with Box-Behnken design method, a statistic-based design of experiments. The optimal operation conditions were obtained by adopting the effectiveness coefficient method on the multi-objective problem, which takes the protein recovery, purification efficiency and throughput of ion-exchange chromatography into account. After the optimization, protein recovery of 96.8% and purity higher than 95% DsbA was achieved, and the productivity was （377.9±1.7） mg soluble DsbA per liter broth. The purified protein was identified by peptide mass fingerprinting matching the record of gil2624856, a mutant of DsbA. The DsbA was preliminarily applied to the refolding of denatured lysozyme in vitro.

Disulfide Crosslinking-Induced Aggregation:Towards Solid-State Fluorescent Carbon Dots with Vastly Different Emission Colors

Solid-state fluorescent multi-color carbon dots(SFM-CDs),prepared using the same precursor(s)without the need for dispersion in a solid matrix,are highly demanded for a wide range of applications.Herein,we report a microwave-assisted strategy for the prepara-tion of SFM-CDs with blue,yellow and red emissions within 5 min from the same precursors.The as-prepared B-CDs,Y-CDs,and R-CDs possessed bright fluorescence at 425 nm,550 nm,and 640 nm,and photoluminescence quantum yields(PLQYs)of 54.68%,17.93%,and 2.88%,respectively.The structure of SFM-CDs consisted of 5-oxo-3,5-dihydro-2H-thiazolo[3,2-a]pyridine-7-carboxylic acid(TPCA)immobilized on the surface of a carbon core,with the size of the carbon core and degree of disulfide crosslinking between CDs both increasing on going from the B-CDs to the R-CDs,as verified by mechanochromic experiments.The excellent solid-state fluorescence performance of the SFM-CDs allowed their utilization as the fluorescent converter layer in multi-color LEDs and white LEDs with a high color rendering index.

Synthesis, Characterization and Crystal Structure of a New Schiff Base Ligand from a Bis(Thiazoline) Template and Hydrolytic Cleavage of the Imine Bond Induced by a Co(II) Cation

The reaction of bis-[2-amino-4-pheny1-5-thiazolyl] disulfide with 5-nitro-salicylaldehyde in absolute ethanol resulted in the formation of a new Schiff base ligand H2L (1). Characterization of the ligand was performed by FT-IR, 1H NMR, 13C NMR, UV-Vis, elemental analysis and single crystal X-ray diffraction. The ligand, (1), possesses a disulfide –S–S– bridge of 2.1121 (3) ? length, and the molecule adopts a cis-conformation around this bond. In the crystal structure of (1), an intramolecular O–H···N hydrogen bond with D… A distance of 2.69 (3) ? was present. The reaction of (1) with Co(NO3)2·6H2O and CuCl2·2H2O in methanol afforded the corresponding metal complexes. The obtained solids were further investigated by elemental analysis and UV-Vis titration that confirmed the formation of [CoL] and [ClCuHL] complexes. However, recrystallizaion of the Co(II) complex in dimethylsulfoxide caused the complete hydrolysis of the imine bond and afforded a Co(II) complex in which two 5-nitro-salicylaldehyde and two DMSO molecules were coordinated to the central metal in an octahedral fashion. This structure (2) was also confirmed by single crystal X-ray analysis.

The effect of lengths of branched-chain fatty alcohols on the efficacy and safety of docetaxel-prodrug nanoassemblies

The self-assembly prodrugs are usually consisted of drug modules,activation modules,and assembly modules.Keeping the balance between efficacy and safety by selecting suitable modules remains a challenge for developing prodrug nanoassemblies.This study designed four docetaxel(DTX)prodrugs using disulfide bonds as activation modules and different lengths of branched-chain fatty alcohols as assembly modules(C_(16),C_(18),C_(20),and C_(24)).The lengths of the assembly modules determined the self-assembly ability of prodrugs and affected the activation modules’sensitivity.The extension of the carbon chains improved the prodrugs’self-assembly ability and pharmacokinetic behavior while reducing the cytotoxicity and increased cumulative toxicity.The use of C_(20) can balance efficacy and safety.These results provide a great reference for the rational design of prodrug nanoassemblies.

In situ autophagy regulation in synergy with phototherapy for breast cancer treatment

Autophagy is an important factor in reducing the efficacy of tumor phototherapy(including PTT and PDT).Accurate regulation of autophagy in tumor cells is a new strategy to improve the anti-tumor efficiency of PTT/PDT.This project intended to construct a tumor-activated autophagy regulator to efficiently block PTT/PDT-induced autophagy and realize synergistic sensitization to tumor phototherapy.To achieve this goal,we first synthesized TRANSFERRIN(Tf)biomimetic mineralized nano-tellurium(Tf-Te)as photosensitizer and then used disulfide bond reconstruction technology to induce Tf-Te self-assembly.The autophagy inhibitor hydroxychloroquine(HCQ)and iron ions carried by Tf were simultaneously loaded to prepare a tumor-responsive drug reservoir Tf-Te/HCQ.After entering breast cancer cells through the“self-guidance system”,Tf-Te/HCQ can generate hyperpyrexia and ROS under NIR laser irradiation,to efficiently induce PTT/PDT effect.Meanwhile,the disulfide bond broke down in response to GSH,and the nanoparticles disintegrated to release Fe2+and HCQ at fixed points.They simultaneously induce lysosomal alkalinization and increased osmotic pressure,effectively inhibit autophagy,and synergistically enhance the therapeutic effect of phototherapy.In vivo anti-tumor results have proved that the tumor inhibition rate of Tf-Te/HCQ can be as high as 88.6%on 4T1 tumor-bearing mice.This multifunctional drug delivery system might provide a new alternative for more precise and effective tumor phototherapy.

Room-temperature Self-healing and Recyclable PDMS Elastomers with Superior Mechanical Properties for Triboelectric Nanogenerators

Polydimethylsiloxane(PDMS)is an electron-withdrawing material that is widely used in triboelectric nanogenerators(TENGs).However,PDMS has poor mechanical properties after curing and is easily damaged when subjected to long-term workloads.Thus,the long-term stable operation of TENGs under mechanical deformation cannot be guaranteed.In this work,multiple hydrogen bonds and aromatic disulfide bonds were introduced into PDMS elastomers.These elastomers exhibited high toughness(a tensile strength of 1.91 MPa and an elongation at break of 340%),good recyclability,and room-temperature self-healing properties(healing efficiency of 96.4%in 24 h).Recyclable sandwich-like triboelectric nanogenerators with excellent electrical output performance(13.5 V)and room-temperature self-healing performance(24 h,98%recovery of self-generating performance)were prepared by utilizing the hydrogen bonding between the PDMS elastomer and MXene.The work reported herein offers theoretical guidance and a compelling strategy for developing high-performance TENG negative friction layers.