Latest ArticlesWe have synthesized a series of compounds based on a piperidyl benzimidazole carboxamide structure, and tested their PARP-1 inhibitory activity, as well as cellular inhibitory activity. Some of them show great potency as PARP-1 inhibitors and antitumor activity, which are valuable for further research. In addition, the predicted ADME properties and proposed binding mode with PARP-1 of the compounds were obtained via computational simulation.
Fourteen avermectin B2a aglycon derivatives were designed and synthesized after removing the oleandrose disaccharide of avermectin B2a. Their structures were characterized by 1H NMR, 13C NMR, HMRS. Preliminary bioassays indicated that these compounds exhibited good insecticidal activity against diamondback moth at 200 mg/L, with mortality no less than 90%. Compounds 10b, 12a, 12c, 17 demonstrated good acaricidal activity against the adult mites, larvae, and good inhibition rate of hatching to mite eggs of Tetranychus cinnabarinus. Compounds 5, 10b, 10c exhibited excellent fungicidal activity against fourteen fungal pathogens in vitro. 3D-QSAR analysis showed that the fungicidal activity of avermectin B2a aglycon derivatives would be increased when a negatively charged and bulky group was introduced at 13-position, which will be instructive for the further modification of avermectin B2a aglycon.
The preparation of silver nanoparticles (AgNPs) with microbe or plant tissues as bio-template offers green approach, while it suffers from low harvest and purification is needed. Herein, we propose a facile protocol for one-pot preparation of AgNPs using M13 phage as bio-template by simply mixing AgNO3 solution with alkali M13 phage. In the obtained AgNPs-M13 phage composite, Cr(Ⅲ) selectively coordinates with the amino residues on phage surface and leads to the aggregation of AgNPs through the bridging of M13 phages. This makes it feasible for colorimetric sensing of Cr(Ⅲ) by measuring the absorbance ratio of AgNPs at 600 and 405 nm, which provides a LOD of 14 nmol/L. The composite also showed favorable bactericidal activity for both Gram-positive and Gram-negative bacteria, making it a promising candidate as antibacterial film in chromium-containing dental alloys and meanwhile serve as a sensing probe for monitoring the corrosion of the dental alloys.
Undesired adsorption of proteins brings big troubles to marine structures. The settled proteins change the physical and chemical properties of the surfaces, which allow marine fouling organisms to settle down on the structures. Therefore, to understand the adsorption mechanism of proteins is very helpful to find an environment-friendly solution against biofouling. Many approaches have been developed to study protein adsorption, but most of them are insufficient to give the chemical interaction information between proteins and surfaces. Fourier transform infrared spectroscopy with attenuated total reflection (FTIR-ATR) is an efficient, fast and non-destructive method for in situ surface measurement, which greatly minimizes the interference of water to infrared spectra, because of the very small depth of penetration of the evanescent wave. In this paper, an in situ FTIR-ATR technology was used to investigate the adsorption process of trypsin on a bare ZnSe surface and on a TiO2 coated ZnSe surface, and the effect of calcium cation strength and ultraviolet light irradiation on the secondary structure of trypsin were also evaluated. FTIR spectra of trypsin showed that Amide Ⅰ band red shift and Amide Ⅱ band blue shift in aqueous environment on both surfaces compared with the dry trypsin powder, and the addition of calcium cations further changed the Amide bands position, which indicated that the change of the secondary structure could be interfered by the environment. The hydrogen bond formation between water and trypsin, the interaction between surface and trypsin, the interaction between hydrated calcium cations and trypsin, are major factors to change the secondary structure of trypsin, and UV light irradiation also showed its influence for the secondary structure.
The detection of biomarkers is of great significance in the diagnosis of numerous diseases, especially cancer. Herein, we developed a sensitive and universal fluorescent aptasensor strategy based on magnetic beads, DNA G-quadruplex, and exonuclease Ⅲ (Exo Ⅲ). In the presence of a target protein, a label-free single strand DNA (ssDNA) hybridized with the aptamer was released as a trigger DNA due to specific recognition between the aptamer and target. Subsequently, ssDNA initiates the Exo Ⅲ-aided recycling to amplify the fluorescence signal, which was caused by N-methylmesoporphyrin Ⅸ (NMM) insertion into the G-quadruplex structure. This proposed strategy combines the excellent specificity between the aptamer and target, high sensitivity of the fluorescence signal by G-quadruplex and Exo Ⅲaided recycling amplification. We selected (50-1200 nmol/L) MUC1, a common tumor biomarker, as the proof-of-concept target to test the specificity of our aptasensor. Results reveal that the sensor sensitively and selectively detected the target protein with limits of detection (LODs) of 3.68 and 12.83 nmol/L in buffer solution and 10% serum system, respectively. The strategy can be easily applied to other targets by simply substituting corresponding aptamers and has great potential in the diagnosis and monitoring of several diseases.
In this manuscript, we first report an ultrasensitive detection assay of microRNA by combing asymmetric polymerase chain reaction (A-PCR) and loop-mediated isothermal amplification (LAMP) technology. Using A-PCR obtained an extended single strand to form LAMP stem-loop structure under isothermal amplification conditions. We used miRNAs as a loop primer probe in LAMP reaction and completed its ultrasensitive and rapid detection. The established method furnished a fast, specific and efficient detection of target miRNA with a detection limit as low as 10 amol/L in 90 min.
Cysteine chemistry provides a low cost and convenient way for site-specific protein modification. However, recombinant expression of disulfide bonding containing protein with unpaired cysteine is technically challenging and the resulting protein often suffers from significantly reduced yield and activity. Here we used genetic code expansion technique to introduce a surface exposed self-paired dithiol functional group into proteins, which can be selectively reduced to afford active thiols. Two compounds containing self-paired disulfides were synthesized, and their genetic incorporations were validated using green fluorescent proteins (GFP). The compatibility of these self-paired di-thiols with natural disulfide bond was demonstrated using antibody fragment to afford site-specifically labeled antibody. This work provides another valuable building block into the chemical tool-box for site-specific labeling of proteins containing internal disulfides.
The rapid transmission of vaccinia virus (VACV) in vivo is thought to be closely related to the cell migration induced by it. Cell migration involved in dynamic changes of cell-substrate adhesion and actin cytoskeleton organization, which can influence by the micro/nano-scale topographic structures that cells are naturally exposed to via contact guidance. However, migration behaviors of VACV-infected cells exposed to topographic cues are still unknown. Herein, we designed an open chip with microgrooved poly(dimethyl siloxane) (PDMS) substrate to explore the topography roles in VACV-induced cell migration. Differed from the random cell migration observed in traditional scratch assay on planar substrate, VACV-infected cells had a tendency to persistently migrate along the axis parallel to microgroove with increased velocity. Moreover, infected cells exhibited a dominant elongated protrusion aligned to the micro-grating axis compare to the shorter lamella extended in any direction on smooth substrate. Interestingly, the Golgi complex preferred to relocate behind the nucleus confined within the micro-grating axis in majority of infected migratory cells. The directional polarization of cells embodied in protrusion formation and Golgi reorientation was responsible for the directionally persistent migration behaviors induced by VACV on microgrooved substrate. Infected cells response to substrate topography, causing the actin-filled stretched protrusion containing numerous virions and accelerated movement is likely to facilitate direct and rapid spread of VACV. This work opens a window for us to understand the migration behaviors of infected cells in vivo, and also provides a cue for revealing the relationship between virus-induced cell migration and virus rapid spread.
Circulating tumor DNA (ctDNA), carrying tumor-specific sequence mutations, is a promising biomarker for classification, diagnosis and prognosis of cancers. However, there is still a great challenge in discriminating single-base difference between ctDNA and its coexisting analogue (normal circulating DNA, ncDNA) at a serum sample. A locked nucleic acid (LNA) probe combined with α-HL nanopore sensor was designed, which achieved a high signal-to-background ratio (SBR) of ~8.34×103, as well as a significant discrimination capability (~12.3 times) of single-base difference. The accurate discrimination strategy is label-free, convenient, selective and sensitive, which has great potential in the early diagnosis of diseases and biomedical research fields.
The residues of organophosphorus pesticide (OPs) on fruits and vegetables pose a threat to human health, so it is very meaningful to explore simple and fast detect methods for OPs residual. In this work, nickel ferrite/nickel oxide nanoparticles co-loaded three-dimensional reduced graphene oxide (3DRGO-NiFe2O4/NiO NPs), as a new low cost nanocomposite, was prepared. Based on its high performance mimetic peroxidase activity, a colorimetric method for the detection of OPs has been developed. Dichlorvos was chosen as model compounds to evaluate the detection performance. The detection linear range for dichlorvos is from 50 mg/mL to 2.5×104 mg/mL with a detection limit of 10 mg/mL. Furthermore, a test paper can be developed based on the 3DRGO-NiFe2O4/NiO NPs for visual detection of dichlorvos, and the image information of the paper sensor can be converted into digital signal and quantitative detection by a smartphone. Notably, this method can also be used to detect dichlorvos in real samples, including vegetables and fruits. Thus, the developed naked assay holds great potential in simple, inexpensive and rapid detection of OPs in fruit and vegetable samples.
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