Latest ArticlesSmall peptides have attracted increasing attention for their unique features and diverse biological functions. Achieving rapid separation and accurate quantification, however, remains a challenge because of their low abundance and the co-existence of numerous structural isomers. In this study, we developed a novel approach using isotope chemical labeling for ultrasensitive determination of di/tripeptides in biological samples. We successfully synthesized a novel derivatization reagent, 4-(2-(ethoxymethylene)-3-oxobutanamido)-N,N,N-trimethylbenzenaminium iodide (EOTMBA) as well as its deuterium-labeled isotope reagent (d3-EOTMBA). A total of 97 small peptides, including 89 dipeptides and 8 tripeptides, could be completely derivatized in methanol within 1.5 h at 60 ℃. After EOTMBA labeling, analysis of these di/tripeptides were achieved within 22 min by LC-MS/MS analysis. The method demonstrated 86.3%–113% accuracy and the limit of quantification ranged from 0.25 fmol/L to 5 nmol/L. Using this method, we achieved ultrasensitive and accurate quantification of di/tripeptides in 147 plasma, 49 urine and 46 bile samples obtained from healthy individuals and patients with biliary tract diseases. The identified differential di/tripeptide biomarker panels showed promising diagnostic performance for patients with biliary tract cancer with area under the receiver operating curve values from 0.870 to 0.996. Furthermore, this method was successfully applied to quantify di/tripeptides in the extract of an animal-derived traditional Chinese medicine, Eupolyphaga sinensis Walker. These findings highlight the possible application of the analytical method in clinics and for the purposes of quality control of traditional Chinese medicines.
The construction of enzyme reactors based on metal-organic frameworks (MOFs) as the immobilized matrix is a proven strategy that has achieved the widespread application of enzymes across industries. Although many MOFs and a variety of strategies have been developed, a formidable challenge remains in maintaining the high enzyme activity with excellent recyclability and tolerance for harsh conditions. Herein, using degradable redox stimuli-responsive liposomes as the templates with microporous MOFs (M-MOFs) as the hosts for enzyme encapsulation, a series of enzyme reactors (enzyme@M-MOFs) was designed and created. Based on the premise of enhancing enzyme protection in the harsh environment, this strategy provided a high degree-of-freedom space via removal of liposomes that improved the conformational freedom of the enzymes, promoted the mass transfer of substrates and products, and greatly boosted the catalytic activity. Importantly, the strategy had good universality and was applied to various liposomes, M-MOFs and enzymes. Additionally, the co-encapsulation of different enzymes with synergistic functions was performed using the M-MOFs platform. This study solved the problems of the conformation limitation of enzymes and mass transfer resistance of substrates and products using the proposed enzyme@M-MOFs, providing a new approach for the construction of biological cascade reaction devices based on MOFs materials.
The device configuration with mesoporous titanium dioxide (m-TiO2) has garnered considerable attention as a promising solution for high-stable perovskite and dye-sensitized solar cells, although its application in organic solar cells remains unexplored. In this communication, we have incorporated this structure into both bulk-heterojunction (BHJ) and single-component organic solar cells (SCOSCs). Surprisingly, mesoporous OSCs (M-OSCs) demonstrate a deteriorative efficiency in BHJ-type cells, whereas this configuration succeeds in SCOSCs, exhibiting competitive performance with planar OSCs (P-OSCs). This pioneering study has resulted in a competitive power conversion efficiency of 9.67% for m-TiO2-based cells, marking a significant milestone in the advancement of OSCs. Importantly, profiting from the better ultraviolet resistance of m-TiO2 than zinc oxide, this M-OSC exhibits superior photostability than that of P-OSCs when subjected to continuous one-sun (AM1.5G) illumination. In its entirety, this research not only introduces the concept of M-OSCs for the first time but also unveils a novel device architecture poised to address the long-term stability concerns within the realm of OSCs.
Regulation of cell fate requires the establishment and erasure of 5-methylcytosine (5mC) in genomic DNA. The formation of 5mC is achieved by DNA cytosine methyltransferases (DNMTs), whereas the removal of 5mC can be accomplished by various pathways. Aside from ten-eleven translocation (TET)-mediated oxidation of 5mC followed by thymine DNA glycosylase (TDG)-initiated base excision repair (BER), the direct deformylation of 5-formylcytosine (5fC) and decarboxylation of 5-carboxylcytosine (5caC) have also been discovered as the novel DNA demethylation pathways. Although these novel demethylation pathways have been identified in stem cells and somatic cells, their precise roles in regulating cell fate remain unclear. Here, we differentiate mouse embryonic stem cells (mESCs) into mouse embryoid bodies (mEBs), followed by further differentiation into mouse neural stem cells (mNSCs) and finally into mouse neurons (mNeurons). During this sequential differentiation process, we employ probe molecules, namely 2′-fluorinated 5-formylcytidine (F-5fC) and 2′-fluorinated 5-carboxyldeoxycytidine (F-5caC), for metabolic labeling. The results of mass spectrometry (MS) analysis demonstrate the deformylation and decarboxylation activities are progressively decreased and increased respectively during differentiation process, and this opposite demethylation tendency is not associated with DNMTs and TETs.
Developing applicable methods to forge linkages between sp3 and sp2-hydridized carbons is of great significance in drug discovery. We show here a new, Ni-catalyzed reductive cross-coupling reaction that forms Csp3−Csp2 bonds from aryl iodides and cyclic sulfonium salts. Notably, Csp3−Csp2 bonds can be forged selectively at the iodine-bearing carbon of bromo(iodo)arenes which is usually recognized as a huge challenge under the catalytic reductive cross-coupling (CRCC) conditions. Experimental and computational mechanistic studies support LNiⅠAr as an active species, while the untraditional anti-Markovnikov selective alkylation of asymmetric sulfonium salts is determined by the oxidative S-substitution of sulfonium salts with LNiⅠAr. This protocol further expands the range of alkyl electrophiles under the CRCC conditions and provides a new strategy for the construction of Csp3−Csp2 bonds.
In this study, the environmentally friendly precursor, tartaric acid (TA), was employed for the generation of CO2 anion radical (CO2•−) in an advanced UV/TA/Fe3+ system to reduce the hazardous -N in wastewater. To optimize this process, various factors, including the dosage of Fe3+, TA, and pH, were systematically investigated for their impact on the reduction process. Under the conditions of 3 mmol/L Fe3+ dosage, 10 mmol/L TA dosage, and a pH of 2.5, -N was effectively removed from the water within 60 min, selectively transformed into N2, with a remarkable N2 selectivity of 91.2%. In the optimal conditions, the -N reduction mechanism in the UV/TA/Fe3+ system and the critical role of were illustrated. Finally, this study explored the reduction of real nitrified seawater using the UV/TA/Fe3+ system. The results demonstrated that the UV/TA/Fe3+ system could completely eliminate -N and achieve a N2 selectivity of up to 90%, with minimal interference from coexisting ions. This work holds promising implications for the environmentally benign treatment of nitrite-polluted wastewater.
Heterojunction engineering is recognized as a promising strategy to modulate the photocatalytic properties of semiconductors. Herein, lead-free Cs2CuBr4 perovskite quantum dots (PQDs) were confined in a mesoporous CuO framework and a p-n type S-scheme heterojunction of Cs2CuBr4/CuO (CCB/CuO) photocatalyst was fabricated. Experimental characterizations confirmed the effective confinement of the Cs2CuBr4 PQDs in the mesoporous CuO framework, which enabled intimate contact in the interface of CCB/CuO heterojunction, thus facilitating the interfacial charge migration and separation between p-type CuO and n-type Cs2CuBr4. Owing to the outstanding charge transport property and CO2 adsorption capacity, the developed CCB/CuO heterojunction exhibited remarkably enhanced photocatalytic CO2 conversion efficiency with an electron consumption rate (Relectron) of 281.1 µmol g−1 h−1, which was approximately 2.8 times higher than that of pristine Cs2CuBr4. These findings provide some insights into the rational engineering design of lead-free perovskite-based heterostructures for efficient photocatalytic CO2 conversion.
Shape-persistent arylene ethynylene molecular cages have been investigated as transmembrane channels for ions and small molecules. The molecular cages were obtained starting from tetrayne monomers through alkyne metathesis cyclooligomerization. We found these porphyrin-based rigid molecular cages can insert into the lipid bilayer and efficiently transport ions and small molecules (e.g., calcein). Our study reveals longer hydrophobic alkyl chains on the cage molecule promote the channeling efficiency, while shorter and/or more polar side chains impair such activity. Kinetic analysis shows linear correlation between the rate of proton transport and the concentration of the cage, suggesting the active species is likely a monomeric cage. We found that C70-encapsulated cages are nearly inactive for transmembrane ion transportation, indicating that ions are likely transported through the internal cavity of the cage. Discrete shape-persistent organic cages represent highly stable synthetic ion channels or pores, which could have interesting applications in biomimetic signaling and drug delivery.
The design and synthesis of organic high-temperature reversible thermochromic materials is one of the difficult issues in the field of organic chromic materials. In this paper, four diacetylene monomers named DBA-PCDA, TBA-PCDA, DBE-PCDA and TBE-PCDA, each containing multiple diacetylene units, were synthesized from 10,12-pentacosadiynoic acid (PCDA) through the amidation or esterification reactions, using 4,4′-diaminobiphenyl, 1,3,5-tris(4-aminophenyl)benzene, 4,4′-dihydroxybiphenyl, and 1,3,5-tris(4-hydroxyphenyl)benzene as bridging units. The effects of functional groups that can form hydrogen bond and π-π interactions on the solid-state polymerization properties of monomers and the thermochromic properties of the corresponding PDAs were investigated. The results show that only DBA-PCDA and TBA-PCDA, which contain functional groups that can form hydrogen bonding interactions, can be polymerized under 254-nm UV irradiation. The corresponding poly(DBA-PCDA) exhibits reversible thermochromic property even heated up to 200 ℃, showing a potential application in the field of high-temperature thermal indicator above 100 ℃. This work provides a new perspective to the development of PDA with high-temperature reversible thermochromic property.
Metal-catalyzed alkene arylalkoxylation is a powerful complexity-building strategy for the synthesis of oxygen heterocycles from simple γ-unsaturated alcohols, but only a few examples of catalytic enantioselective methods exist. Herein, an efficient palladium-catalyzed enantioselective arylalkoxylation of γ-hydroxyalkenes with aryl halides is reported. The salient features of this transformation include a remarkable broad substrate scope, mild reaction conditions, and good functional group tolerance, delivering a series of chiral tetrahydrofurans containing a tertiary or quaternary stereocenter in good yields with up to 95% ee. The Xu10 ligand with a suitable side-arm was responsible for the high reactivity and good enantioselectivity of this transformation.
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