High‐Throughput,Label‐Free Isolation of Cancer Stem Cells on the Basis of Cell Adhesion Capacity

Herein we report a microfluidics method that enriches cancer stem cells (CSCs) or tumor‐initiating cells on the basis of cell adhesion properties. In our on‐chip enrichment system, cancer cells were driven by hydrodynamic forces to flow through microchannels coated with basement membrane extract. Highly adhesive cells were captured by the functionalized microchannels, and less adhesive cells were collected from the outlets. Two heterogeneous breast cancer cell lines (SUM‐149 and SUM‐159) were successfully separated into enriched subpopulations according to their adhesive capacity, and the enrichment of the cancer stem cells was confirmed by flow cytometry biomarker analysis and tumor‐formation assays. Our findings show that the less adhesive phenotype is associated with a higher percentage of CSCs, higher cancer‐cell motility, and higher resistance to chemotherapeutic drugs.     

Facile synthesis of nitrogen-doped carbon dots for Fe sensing and cellular imaging

A fast and facile approach to synthesize highly nitrogen (N)-doped carbon dots (N-CDs) by microwave-assisted pyrolysis of chitosan, acetic acid and 1,2-ethylenediamine as the carbon source, condensation agent and N-dopant, respectively, is reported. The obtained N-CDs are fully characterized by elemental analysis, transmission electron microscopy, high-resolution transmission electron microscopy, Fourier transform infrared spectroscopy, Raman spectroscopy, X-ray diffraction pattern, X-ray photoelectron spectroscopy, UV–vis absorption, and photoluminescence spectroscopy. Doping N heteroatoms benefits the generation of N-CDs with stronger fluorescence emission. As the emission of N-CDs is efficiently quenched by Fe³⁺, the as-prepared N-CDs are employed as a highly sensitive and selective probe for Fe³⁺ detection. The detection limit can reach as low as 10 ppb, and the linear range is 0.010–1.8 ppm Fe³⁺. The as-synthesized N-CDs have been successfully applied for cell imaging and detecting Fe³⁺ in biosystem.     

A novel electrochemical immunosensor using β-cyclodextrins functionalized silver supported adamantine-modified glucose oxidase as labels for ultrasensitive detection of alpha-fetoprotein

In this work, a novel sandwich-type electrochemical immunosensor based on host-guest interaction was fabricated for the detection of alpha-fetoprotein (AFP). Due to the large specific surface area of multiwalled carbon nanotubes and the unique supramolecular recognition ability of β-cyclodextrins, ferrocenecarboxylic acid (Fc) was incorporated into this sensor platform by host-guest interaction to generate an electrochemical signal. And β-cyclodextrins functionalized silver supported adamantine-modified glucose oxidase (GOD-CD-Ag), was used as a label to improve the analytical performance of the immunosensor by the dual amplification strategy. The obtained GOD-CD-Ag conjugates could convert glucose into gluconic acid with the formation of hydrogen peroxide (H₂O₂). And then silver nanoparticles could in situ catalyze the reduction of the generated H₂O₂, dramatically improving the oxidation reaction of Fc. The developed immunosensor shows a wide linear calibration range from 0.001 to 5.0 ng/mL with a low detection limit (0.2 pg/mL) for the detection of AFP. The method, with ideal reproducibility and selectivity, has a wide application prospect in clinical research.     

Humic acids as both matrix for matrix-assisted laser desorption/ionization time-of-flight mass spectrometry and adsorbent for magnetic solid phase extraction

In the present study, humic acids (HAs) were applied as both a matrix for matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) and an adsorbent of magnetic solid phase extraction (MSPE) for the first time. As natural macromolecule compounds, HAs are inherently highly functionalized and contain laser energy absorbing–transferring aromatic structures. This special molecular structure made HAs a good candidate for use as a MALDI matrix in small molecule analysis. At the same time, due to its good adsorption ability, HAs was prepared as MSPE adsorbent via a simple co-mixing method, in which the commercially available HAs were directly mixed with Fe₃O₄ magnetic nanoparticles (MNPs) in a mortar and grinded evenly and completely. In this process, MNPs were physically wrapped and adhered to tiny HAs leading to the formation of magnetic HAs (MHAs). To verify the bi-function of the MHAs, Rhodamine B (RdB) was chosen as model compound. Our results show that the combination of MHAs-based MSPE and MALDI-TOF-MS can provide a rapid and sensitive method for the determination of RdB in chili oil. The whole analytical procedure could be completed within 30 min for simultaneous determination of more than 20 samples, and the limit of quantitation for RdB was found to be 0.02 μg/g. The recoveries in chili oil were in the range 73.8–81.5% with the RSDs less than 21.3% (intraday) and 20.3% (interday). The proposed strategy has potential applications for high-throughput analysis of small molecules in complex samples.     

High‐Throughput,Label‐Free Isolation of Cancer Stem Cells on the Basis of Cell Adhesion Capacity

Herein we report a microfluidics method that enriches cancer stem cells (CSCs) or tumor‐initiating cells on the basis of cell adhesion properties. In our on‐chip enrichment system, cancer cells were driven by hydrodynamic forces to flow through microchannels coated with basement membrane extract. Highly adhesive cells were captured by the functionalized microchannels, and less adhesive cells were collected from the outlets. Two heterogeneous breast cancer cell lines (SUM‐149 and SUM‐159) were successfully separated into enriched subpopulations according to their adhesive capacity, and the enrichment of the cancer stem cells was confirmed by flow cytometry biomarker analysis and tumor‐formation assays. Our findings show that the less adhesive phenotype is associated with a higher percentage of CSCs, higher cancer‐cell motility, and higher resistance to chemotherapeutic drugs.     

Correlation between electron delocalization and structural planarization in small water rings

The discovery of the covalent‐like character of the hydrogen bonding (H‐bonding) system [Science 342 , 611(2013)] has promoted a renewal of our understanding of the electronic and geometric structures of water clusters. In this work, based on density functional theory calculations, we show that the preferential formation of a stable quasiplanar structure of (H₂O)_n(n = 3–6) is closely related to three kinds of delocalized molecular orbitals (MOs; denoted as MO‐I, II, and III) of water rings. These originate from the 2p lone pair electrons of oxygen (O), the 2p bond electrons of O and the 1s electrons of H and the 2s electrons of O and 1s electrons of H, respectively. To maximize the orbital overlaps of the three MOs, geometric planarization is needed. The contribution of the orbital interaction is more than 30% in all the water rings according to our energy decomposition analysis, highlighting the considerable covalent‐like characters of H‐bonds. © 2015 Wiley Periodicals, Inc.     

Single nucleotide polymorphisms of mitochondrial DNA HVS‐I and HVS‐II in Chinese Bai ethnic group

For forensic and population genetic purposes, a total of 125 unrelated volunteers’ blood samples were collected from Chinese Bai ethnic minority group to analyze sequence variation of two hypervariable segments (HVS‐I and HVS‐II) in the mitochondrial DNA control region. Comparing the HVS‐I and HVS‐II sequences of the 125 Chinese Bais to the Anderson reference sequence, we found 86 polymorphic loci in HVS‐I and 40 in HVS‐II in mitochondrial DNA sequences of the Chinese Bai ethnic minority group, which defined 93 and 53 different haplotypes, respectively. Haplotype diversity and the mean pairwise differences were 0.992 ± 0.003 and 6.553 in HVS‐I, and 0.877 ± 0.027 and 2.407 in HVS‐II, respectively. We defined four macrohaplogroups R, M, N and D with the proportions ranging from 9.6% to 40.0%. With the analysis of the hypervariable domain from nucleotide 16 180–16 193 in HVS‐I, our study revealed new haplotypes of sequence variations. In addition, the Fst metric, phylogenetic tree, and principal component analysis demonstrated a close genetic relationship between the Bai group and Chinese Han populations from South China, Changsha, and Guangdong. The results support that the Bai group is a multiorigin ethnic minority that has merged with the Chinese Han population.     

蒽醌类亲脂性阳离子的合成及抗癌活性

合成了7个大黄素季铵盐、2个芦荟大黄素季铵盐、1个水溶性大黄素季铵盐和1个α-萘酚醌苯基甲烷季铵盐化合物,并测试了其抗癌活性.含有1条长碳链的大黄素季铵盐的抗癌活性很低,但是含有2条长碳链的大黄素和芦荟大黄素季铵盐的抗癌活性较好.用亲水性的长链替代季铵盐中亲脂性的长碳链会导致大黄素季铵盐失去抗癌活性.α-萘酚醌苯基甲烷季铵盐显示了中等的抗癌活性,表明在具有电子传递能力的分子中引入亲脂性的长碳链季铵盐可以增加其抗癌活性.     

A new natural nucleotide and other antibacterial metabolites from an endophytic Nocardia sp.

Nine compounds were isolated from Nocardia sp. YIM 64630, and their structures were elucidated as 5′-O-acetyl-2′-deoxyuridine (1), 22E,24R-5α,6α-epoxyergosta-8(14),22-diene-3β,7α-diol (2), 22E,24R-5α,6α-epoxyergosta-8,22-diene-3β,7α-diol (3), 22E,24R-ergosta-7,22-diene-3β,5α,6β-triol (4), 5α,8α-epidioxyergosta-6,22-dien-3β-ol (5), 4′,5,6-trihydroxy-7-methoxyisoflavone (6), 2,4,4′-trihydroxy-deoxybenzoin (7), methyl [4-hydroxyphenyl]acetate (8) and daidzein by extensive spectroscopic analyses. Compound 1 was isolated from natural resources for the first time. The antimicrobial and antioxidant activities of compounds 1–8 were investigated.