Latest ArticlesAn electrochemical sensor for doxycycline hyclate (DC) detection with high sensitivity and good selectivity is reported. The sensor was fabricated by electro-polymerization of molecularly imprinted polymers (MIPs) in the presence of DC onto multi-walled carbon nanotubes modified glassy carbon electrode (MWCNTs/GCE). The MWCNTs can significantly increase the current response of the sensor, leading to enhanced sensitivity. The MIPs provide selective recognition sites for DC detection. The experimental parameters, such as the polymer monomer concentration, supporting electrolyte pH, the time for electro-polymerization and the incubation time of the sensor with DC were optimized. Under optimized experimental conditions, the sensor displayed a linear range of 0.05 μmol/L-0.5 μmol/L towards DC detection, with the detection limit of 1.3×10-2 μmol/L. The sensor was successfully applied for recovery test of DC in human serum samples.
The construction of N-methyl amine moieties is an important reaction that has found numerous applications. Development of new methylation agents that are more environmentally benign than classical agents, such as iodomethane and methyl sulfate, is still highly desirable. Herein, we report a convenient protocol for direct reductive N-methylation of amines using formic acid as the methylation agent via simple inorganic base catalysis. The present protocol operates under transition-metal-free and air-tolerant conditions. Both the catalyst, K2HPO4, and the reductant, polymethylhydrosiloxane (PMHS), are cheap and easily separable from the crude reaction product mixture. Mechanistic investigations suggest that the reaction occur through the formation of an acetal intermediate followed by the C-N bond formation.
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.
We 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.
It is urgent to find a technology accurately to better diagnose and treat to brain tumor. Eu-doped Gd2O3 nanorods (Eu-Gd2O3 NRs) with paramagnetic and fluorescent properties were conjugated with doxorubicin (Dox) and chlorotoxin (CTX) via PEGylation, hydrazone bond and sulfur bond (named as CTXNRs-Dox), and these NRs could release more Dox in lower pH environment. The results of cell experiments indicated that CTX-NRs-Dox had obvious targeting and toxic effects on U251 cells, as well as good fluorescence imaging behavior. The orthotopic glioma-transplanted mice models were constructed via the intracranial injection of glioma cells (U87MG). The result of experiments after the tail-vein injection of the prepared NRs suggested that CTX-NRs-Dox could target to brain tumors via the long-time blood circulation, leading to their obvious contrast enhancement of MR imaging of the intracranial tumor and their significant inhibitory effect on the growth and metastasis of brain tumors. A mechanism of synergistic effect of CTX-NRs-Dox on targeting and inhabiting the brain tumor was proposed. Our research suggested that CTX-NRs-Dox had potential application prospect in the detection and treatment of glioma.
Efficient catalytic system with low energy consumption exhibits increasing importance due to the upcoming energy crisis. Given this situation, it should be an admirable strategy for reducing energy input by effectively utilizing incident solar energy as a heat source during catalytic reactions. Herein, aza-fused π-conjugated microporous polymer (aza-CMP) with broad light absorption and high photothermal conversion efficiency was synthesized and utilized as a support for bimetallic AuPd nanocatalysts in light-driven benzyl alcohol oxidation. The AuPd nanoparticles anchored on aza-CMP (aza-CMP/AuxPdy) exhibited excellent catalytic performance for benzyl alcohol oxidation under 50 mW/cm2 light irradiation. The improved catalytic performance by the aza-CMP/AuxPdy is attributed to the unique photothermal effect induced by aza-CMP, which can promote the catalytic benzyl alcohol oxidation occurring at AuPd. This work presents a novel approach to effectively utilize solar energy for conventional catalytic reactions through photothermal effect.
Direct conversion of methane (CH4) to methanol (DMTM) is a promising, but very challenging process for the utilization of abundant CH4 as a low carbon resource. In this context, Cu loaded zeolites, mordenite (MOR) in particular, were recognized as the most effective system to perform DMTM. In this work, different Cu salts were used to exchange with MOR, by which the effect of counter ions on the catalytic performance towards DMTM was investigated. The prepared catalysts were characterized and evaluated systematically. It was found that the counter ions affected the speciation of Cu sites, probably due to their capability in extraction of protons from MOR and the influence on the hydrolysis state of the Cu2+ in aqueous solution. These behaviors adjusted the association between Cu2+ and the exchangeable protons in MOR. As a result, varied DMTM performance was observed. Among the used Cu salts, Cu(CH3COO)2 exchanged MOR showed the highest performance, achieving stable CH3OH yield of 117±28 μmol/g in 5 consecutive cycles, these values are among the highest for Cu loaded MOR zeolites in open publications.
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.
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.
Highly luminescent colloidal nanocrystals have wide applications in bioimaging and various optoelectronic devices. Herein we report a facile and mild procedure by combining S2- treatment and binary ligand passivation, which can efficiently enhance the luminescent property of CdSe nanocrystals at room temperature. The photoluminescence quantum yield of as-treated CdSe nanocrystals exhibits drastic enhancement (e.g., 188 times for CdSe nanorods) after this dual-passivation treatment. The methodology proposed here can be applied to various CdSe nanocrystals, regardless of their sizes, shapes, and crystal structures.
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