Latest ArticlesThe metal-free S–S bond exchange reaction of symmetrical disulfides catalyzed by NFSI is described. This novel protocol provides a facile and efficient approach to accessing important unsymmetrical disulfides. Furthermore, this strategy could also be utilized in the late-stage functionalization of amino acids, drugs, and natural products. The broad substrate scope, good functional group tolerance and easy accessibility of catalyst indicate that this strategy affords a green and practical complementary method to various unsymmetrical disulfides.
The visible-light-induced selective oxidation of ubiquitous C–H bonds into valuable C=O bonds under aerobic conditions is one of the most attractive approaches for the construction of carbonyl-containing molecules. In this work, two transition metal-containing Nb/W mixed-addendum POMs dimers with the formula of K2Na2H5[(Fe(H2O)4)3(P2W15Nb3O62)2]·24H2O (POM[Fe]) and K2Na3H4[(Cr(H2O)4)3(P2W15Nb3O62)2]·32H2O (POM[Cr]) have been synthesized and characterized by various analytical and spectral techniques. POM[Fe] was proved to be an efficient photocatalyst for benzylic C–H oxidation under visible light and using oxygen as an oxidant to produce the corresponding carbonyl complex in good yields. A plausible mechanism involving superoxide radical was proposed for the catalytic reaction. POM[Fe] showed good reusability in the recycling experiments. IR spectroscopy and XRD analysis indicate that POM[Fe] can retain its integrity after catalysis.
In the recent decade, GO has emerged as an amazing 2D nanomaterial for developing DNA-based biosensors due to its fluorescence quenching properties, whereas similar research based on rGO was reported rarely. Herein, a novel multi-pyrene functionalized G-rich DNA probe based on the screened rGO showed much higher fluorescence quenching efficiency and excimer emission than that of universal GO. Different from the universal thrombin detection of the G4-forming aptamer-TBA(GGTTGGTGTGGTTGG), the original telomeric sequence is used in this study. The excimer emission "ON-OFF" switch amplified the response of thrombin detection is as low as 50 units. Furthermore, for four pyrene moieties that are sited in a crowded steric circumstance, the melting temperature (Tm) values and molecular dynamics simulations showed a positive effect on duplex G-quadruplex or GDNA·cDNA stability, without disturbing its helix structure.
Hydrogen peroxide (H2O2) is a very simple bioactive small molecule. In living organisms, H2O2 plays an important role in intracellular signaling. It is involved in many physiological processes including cellular physiology, intracellular signaling, oxidative damage and disease progression. The tumor microenvironment enriched with H2O2. Several electrochemical sensors have been developed and some have been put on the market. Such electrochemical sensors provide efficient, cost-effective, rapid and highly selective method of H2O2 detection. So far, much progress has been made in the designing of materials and construction of H2O2 sensors. This review describes the advances in the application of H2O2 electrochemical sensors in cell detection. Enzyme-based sensors have been applied in diverse applications. In addition, recent advancements in nanotechnology have improved the development of nanozymes-based sensors. The application of noble metals, metal oxides, polymers, carbon materials and other two-dimensional materials in the design of H2O2 sensors are discussed in detail. Moreover, the bio-stimulant types of H2O2 sensor are summarized. Finally, the challenges and future perspectives in the application of H2O2 electrochemical sensors in biological detection are discussed.
Two pairs of fluorescent natural products, talarolactones (+)/(−)-A and (+)/(−)-C [(+)/(−)-1 and (+)/(−)-2], were discovered and characterized as a new family of circularly polarized luminescence-active small organic molecules (CPL-SOMs) with high fluorescence efficiency and fascinating CPL properties. The CPL (|glum|) levels of enantiomerically pure (+)/(−)-1 and (+)/(−)-2 in solution falls into the usual range (10−5−10−3) considering their pure organic nature, but the sign of CPL were found to be closely related to the absolute configuration of C-8. The high agreement of the measured CPL spectra of (+)/(−)-1 and (+)/(−)-2 with the time-dependent density functional theory (TDDFT) calculated ones demonstrated the usefulness of CPL-calculation as a unique method for stereochemical assignment. This study may open up a new perspective for the stereochemical studies and the future development of CPL materials.
The development of a single analytical platform with different functions is highly desirable but remains a challenge at present. Here, a paper-based device based on fluorescent carbon dots (CDs) functionalized paper/MnO2 nanosheets (MnO2 NS) hybrid devices (PCD/NS) was proposed for single-device multi-function applications. MnO2 NS functioned as a fluorescence quencher of CDs and recognizer of H2O2 released from the oxidase catalyzed system. Fluorescence recovery would occur after the decomposition of MnO2 NS induced by H2O2, by which a simple and effective strategy could be developed for fluorescence monitoring multiplex biological events. Xanthine (XA) sensing, xanthine oxidase (XOD) inhibitors screening analysis and chiral recognition of glucose enantiomers were performed on PCD/NS to investigate the multifunctional application of the paper-based device. By means of PCD/NS, XA could be determined in the range of 0.1–40 µmol/L with a low detection of limit of 0.06 µmol/L. The IC50 value of allopurinol, the model inhibitor of XOD, was sensitively detected to be 7.4 µmol/L. Glucose enantiomers were also recognized in terms of the specific fluorescence response to d-glucose. This work firstly presented a paper-based device capable of biomarkers detection, inhibitors screening and chiral recognition, which enlightened a promising strategy for the construction of multifunctional devices and hold the great potential application in clinical diagnosis and drug discovery.
The BiOCl (BOC) synthesized by the water bath heating method was treated with sodium borohydride (NaBH4) to introduce oxygen vacancies (OVs). At the same time, Au nanoparticles were loaded to prepare a series of Au/BiOCl samples with different ratios. OVs and Au nanoparticles can promote the light absorption of host photocatalyst in the visible region. The calculated work function of BiOCl and Au can verify the existence of Ohmic contact between the interface of them, which is conducive to the separation of charge carriers. Through a series of photoelectric tests, it was verified experimentally that the separation of charge carriers is indeed enhanced. The high-energy hot electrons produced by Au under the surface plasmon resonance (SPR) effect can increase the counts of electrons to participate in the CO2 reduction reaction. Especially for 1.0%-Au/BOC, the yields of CO can reach 43.16 µmol g−1 h−1, which is 6.6 times more than that of BOC. Therefore, loading precious metal on semiconductors is an effective strategy to promote the photocatalytic performance of CO2 reduction reactions.
A series of near-infrared (NIR) fluorescent substrates (NDRO-1~8) derived from fluorophore NDRH with different volumes of ester bond as the recognition group were designed and synthesized for the detection of acetylcholinesterase (AChE), among which NDRO-1 with the smallest acetate group displayed the highest activity toward AChE. The detection limit of NDRO-1 for sensing AChE was 0.32 µg/mL, and Km was 6.40 µmol/L, indicating ultra-sensitivity and good affinity of NDRO-1 toward AChE. NDRO-1 was used to detect the inhibitory of four kinds of pesticides including methamidophos, dichlorvos, and the detection limit was lower than 50 µg/L, which was further used in pesticide residues detection.
Sulfur dioxide and its derivative sulfite widely existed in air, water as the environment pollutant. Sulfite is also commonly used as preservative and additive in fresh fruits, vegetables, wines and pharmaceutical materials. Due to sulfite is closely related with human diseases, it is very urgent for the sensitive and rapid quantification of sulfite in various samples. In our study, a turn-on near infrared (NIR) fluorescent probe (MDQ) was developed for sulfite detection based on a Michael addition reaction, with high sensitivity (LOD 4.16 nmol/L), selectivity and fast response time (400 s). Using MDQ, a quantify method for sulfite in traditional Chinese medicines (TCMs) was developed with the advantages of high precision, accuracy and convenient operation. Furthermore, according to the photophysical property of MDQ, a portable fluorescence detector is designed to quantify sulfite for TCMs and surface water in Dalian city of China. Therefore, the developed fluorescent probe MDQ and portable fluorescent detector as a rapid inspection instrument were successfully used to real-time monitor the sulfite in various complex samples.
Since the concept of aptamer emerged, many scientists have launched a rich field of research around it. However, few nucleic acids aptamer which use cell as target can be put into practical applications. We believe that a great deal of this lies in the complexity and irreproducibility of aptamer screening experiments themselves. The complexity is due to the cumbersome processes and the technical requirements for laboratory personnel, whereas irreproducibility arises from the fact that the starting point of such screens is nucleic acid libraries with random fragments, and that different libraries directly determine the differences or even the success or failure of screening results. The complexity and irreproducibility mentioned above, in turn, lead to the inability of this experiment to unfold on a large scale, which naturally cannot lead to excellent results for practical applications. In response to this problem, our group has developed an instrument for automated screening of tumor cell nucleic acid aptamers and characterized the properties of nucleic acid aptamers obtained using this instrument in a comprehensive manner.