Aqueous Solution Enhanced Room Temperature Phosphorescence through Coordination-Induced Structural Rigidity.

Achieving aqueous solution enhanced room temperature phosphorescence (RTP) is critical for the applications of RTP materials in solution phase, but which faces a great challenge. Herein, for the first time, a strategy of coordination-induced structural rigidity is proposed to achieve enhanced quantum efficiency of aluminum/scandium-doped phosphorescent microcubes (Al/Sc-PMCs) in aqueous solution. The Al/Sc-PMCs in a dry state exhibit a nearly invisible blue RTP. However, they emit a strong RTP emission in aqueous solution with a RTP intensity increase of up to 22.16-times, which is opposite to common solution-quenched RTP. The RTP enhancement mechanism is attributed to the abundant metal sites (Al3+ and Sc3+ ions) on the Al/Sc-PMCs surface that can tightly combine with water molecules through the strong coordination. Subsequently, these coordinated water molecules as the bridging agent can bind with surface groups by hydrogen bonding interaction, thereby rigidifying chemical groups and inhibiting their motions, resulting in the transition from the nonradiative decay to the radiative decay, which greatly enhances the RTP efficiency of the Al/Sc-PMCs. This work not only develops a coordination rigidity strategy to enhance RTP intensity in aqueous solution, but also constructs a phosphorescent probe to achieve reliable and accurate determination of analyte in complex biological matrices.

Inorganic salt recrystallization strategy for achieving ultralong room temperature phosphorescence through structural confinement and aluminized reconstruction.

Achieving highly efficient and stable room temperature phosphorescence (RTP) with ultralong lifetime is critical for the multi-purpose applications of phosphorescent materials. In this work, we propose an inorganic salt heating recrystallization strategy to simultaneously improve the lifetime, quantum efficiency, and stability of phosphorescent scandium/leucine microspheres (Sc/Leu-MSs). Inorganic salt-treated Sc/Leu-MSs are obtained by simply heating and drying inorganic salt solution containing Sc/Leu-MSs, which can achieve a maximum lifetime increase of 4.42-times from 208.37 ms (Sc/Leu-MSs) to 920.08 ms (Al2(SO4)3-treated Sc/Leu-MSs), accompanied by a RTP intensity increase up to 24.08-times. The enhancement mechanism of RTP efficiency is attributed to the stabilization of triplet excitons caused by inorganic salt coating that suppresses molecular motion and isolates oxygen on the one hand, and the efficient intersystem crossing promoted by aluminized reconstruction-caused duplex heavy atom effects on the other hand. This study provides new design principle and a facile strategy to construct RTP materials with ultralong lifetime, high phosphorescent quantum efficiency, and high stability for promising applications such as anti-counterfeiting and light emitting diodes.

A general method for rapid synthesis of refractory carbides by low-pressure carbothermal shock reduction.

Refractory carbides are attractive candidates for support materials in heterogeneous catalysis because of their high thermal, chemical, and mechanical stability. However, the industrial applications of refractory carbides, especially silicon carbide (SiC), are greatly hampered by their low surface area and harsh synthetic conditions, typically have a very limited surface area (<200 m2 g-1), and are prepared in a high-temperature environment (>1,400 °C) that lasts for several or even tens of hours. Based on Le Chatelier's principle, we theoretically proposed and experimentally verified that a low-pressure carbothermal reduction (CR) strategy was capable of synthesizing high-surface area SiC (569.9 m2 g-1) at a lower temperature and a faster rate (∼1,300 °C, 50 Pa, 30 s). Such high-surface area SiC possesses excellent thermal stability and antioxidant capacity since it maintained stability under a water-saturated airflow at 650 °C for 100 h. Furthermore, we demonstrated the feasibility of our strategy for scale-up production of high-surface area SiC (460.6 m2 g-1), with a yield larger than 12 g in one experiment, by virtue of an industrial viable vacuum sintering furnace. Importantly, our strategy is  also applicable to the rapid synthesis of refractory metal carbides (NbC, Mo2C, TaC, WC) and even their emerging high-entropy carbides (VNbMoTaWC5, TiVNbTaWC5). Therefore, our low-pressure CR method provides an alternative strategy, not merely limited to temperature and time items, to regulate the synthesis and facilitate the upcoming industrial applications of carbide-based advanced functional materials.

In Situ Imaging of Ion Motion in a Single Nanoparticle: Structural Transformations in Selenium Nanoparticles.

Intraparticle ion motions are critical to the structure and properties of nanomaterials, but rarely disclosed. Herein, in situ visualization of ion motions in a single nanoparticle is presented by dark-field microscopy imaging, which shows HgCl2 -induced structural transformation of amorphous selenium nanoparticles (SeNPs) with the main composition of Se8 . Owing to the high binding affinity with selenium and coulomb interactions, Hg2+ ions can permeate into the interior of SeNPs, making the amorphous Se8 turn to polycrystalline Hg3 Se2 Cl2 . As a proof of concept, SeNPs then serve as a highly effective scavenger for selective removal of Hg2+ ions from solution. This new finding offers visual proof for the photophysical process involving intraparticle ion motion, demonstrating that tracking the ion motions is a novel strategy to comprehend the formation mechanism with the purpose of developing new nanostructures like nanoalloys and nano metal compounds.

[Cloning and prokaryotic expression of 3-ketoacyl-CoA thiolase gene AIKAT from Atractylodes lancea].

In this study, the gene encoding the key enzyme 3-ketoacyl-CoA thiolase(KAT) in the fatty acid ß-oxidation pathway of Atractylodes lancea was cloned. Meanwhile, bioinformatics analysis, prokaryotic expression and gene expression analysis were carried out, which laid a foundation for the study of fatty acid ß-oxidation mechanism of A. lancea. The full-length sequence of the gene was cloned by RT-PCR with the specific primers designed according to the sequence information of KAT gene in the transcriptomic data of A. lancea and designated as AIKAT(GenBank accession number MW665111). The results showed that the open reading frame(ORF) of AIKAT was 1 323 bp, encoding 440 amino acid. The deduced protein had a theoretical molecular weight of 46 344.36 and an isoelectric point of 8.92. AIKAT was predicted to be a stable alkaline protein without transmembrane segment. The secondary structure of AIKAT was predicted to be mainly composed of α-helix. The tertiary structure of AIKAT protein was predicted by homology modeling method. Homologous alignment revealed that AIKAT shared high sequence identity with the KAT proteins(AaKAT2, CcKAT2, RgKAT and AtKAT, respectively) of Artemisia annua, Cynara cardunculus var. scolymus, Rehmannia glutinosa and Arabidopsis thaliana. The phylogenetic analysis showed that AIKAT clustered with CcKAT2, confirming the homology of 3-ketoacyl-CoA thiolase genes in Compositae. The prokaryotic expression vector pET-32 a-AIKAT was constructed and transformed into Escherichia coli BL21(DE3) for protein expression. The target protein was successfully expressed as a soluble protein of about 64 kDa. A real-time quantitative PCR analysis was performed to profile the AIKAT expression in different tissues of A. lancea. The results demonstrated that the expression level of AIKAT was the highest in rhizome, followed by that in leaves and stems. In this study, the full-length cDNA of AIKAT was cloned and expressed in E. coli BL21(DE3), and qRT-PCR showed the differential expression of this gene in different tissues, which laid a foundation for further research on the molecular mechanism of fatty acid ß-oxidation in A. lancea.

[Ecological remediation of earthworms on soil-plant system: A review]. / 蚯蚓对土壤-æ¤ç‰©ç³»ç»Ÿç”Ÿæ€ä¿®å¤ä½œç”¨ç ”ç©¶è¿›å±•.

Soil-plant system is the basic structural unit of the biosphere, with close mutual feedback between soil and plants. The degradation of soil exerts various abiotic stresses to plants, disturbs the physiological metabolism of plants, and inhibits nutrient acquisition. Earthworms are known as "ecosystem engineers", which can regulate soil physical-chemical-biological characteristics, improve the quality of the degraded soil (saline soil, heavy metals and organic pollutants contaminated soil), alleviate plants under stress, increase soil nutrient availability, promote plant growth. Furthermore, through the secretion of signal substances, earthworms could improve the resistance of plants. The ecological remediation effects of earthworms on soil-plant system are of great significance for improving environment of plant growth and maintaining the health and stability of soil.

Fluorescent carbon dots functionalization.

Carbon dots (CDs), as a new type of luminescent zero-dimensional carbon nanomaterial, have been applied in a variety of fields. Currently, functionalization of CDs is an extremely useful method for effectively tuning their intrinsic structure and surface state. Heteroatom doping and surface modification are two functionalization strategies for improving the photophysical performance and broadening the range of applications for fluorescent CDs. Heteroatom doping in CDs can be used to tune their intrinsic properties, which has received significant research interests because of its simplicity. Surface modification can be applied for varying active sites and the functional groups on the CDs surface, which can endow fluorescent CDs with the unique properties resulting from functional ligand. In this review, we summarize the structural and physicochemical properties of functional CDs. We focused our review on the latest developments in functionalization strategies for CDs and discuss the detailed characteristics of different functionalization methods. Ultimately, we hope to inform researchers on the latest progress in functionalization of CDs and provide perspectives on future developments for functionalization of CDs and their potential applications.

Metal-Mediated Gold Nanospheres Assembled for Dark-Field Microscopy Imaging Scatterometry.

Developing rapid, sensitive and intelligent optical probes is important for the growing need of microscope imaging analysis. Herein, we proposed a new strategy to assemble plasmonic nanoprobes in situ for dark-field microscopy imaging scatterometry by making use of the formation, disruption, and re-formation of cytosine-Ag+-cytosine (CAg+C) bonds. The CAg+C bond was formed at first through Ag+-mediated base pairing between C-contained aptamer and its C-mismatched complementary DNA. Owing to the subsequent binding of target with the aptamer, the CAg+C structure was disrupted, leading Ag+ to be quantitatively released. The released Ag+ ions can make the CAg+C bonds formed again between the C-contained sequence that modified gold nanospheres (AuNSs), and AuNS clusters thus formed in situ, which have strong plasmonic scattering signals owing to the coupling of localized surface plasmon resonance (LSPR). Therefore, the plasmonic scattering signals enhanced following the off-on mode under the dark field microscope from the 'zero' background to on. As a concept of proof, sensitive detections for Aflatoxin B1 (AFB1) in foods, carcinoembryonic antigen (CEA) in blood serum, and Ricin B in artificial sample, was successfully made by using of the in situ formed AuNS clusters, demonstrating that the newly developed metal-mediated strategy for assembling nanoprobes are universal.

A single gold nanoprobe for colorimetric detection of silver(i) ions with dark-field microscopy.

Highly sensitive colorimetric detection of silver(i) ions (Ag+) at the single-particle level was developed based on the color of a gold nanoparticle (AuNP) assembly captured by dark-field microscopy (DFM) imaging. Formation of C-Ag+-C bonding between cytosines was utilized to induce interparticle coupling of AuNPs modified with single-strand DNA, resulting in a color change as the signal transduction to quantify Ag+ under DFM imaging. This method allowed visual quantitation of Ag+ in the range of 0.05 nM-250.00 nM and a detection limit of 28.8 pM was achieved. Furthermore, we demonstrated its applicability for the colorimetric detection of Ag+ in a small quantity of real samples, showing the good potential of this developed method for environmental monitoring and drug quality control.

Anthrax biomarker: An ultrasensitive fluorescent ratiometry of dipicolinic acid by using terbium(III)-modified carbon dots.

The highly sensitive detection of dipicolinic acid (DPA), a biomarker of the biological threat-agent anthrax, is strongly associated with the sensing of Bacillus anthracis (B. anthracis) in environmental and food samples. In this study, we developed a novel, ultrasensitive method for the detection of DPA by using a ratiometric fluorescent terbium ions modified carbon dots (CDs-Tb). The CDs-Tb showed two fluorescent emission bands at 459 nm and 495 nm when excited at the single wavelength of 260 nm. DPA could specifically bind with terbium ions on the surface of CDs through strong chelate-conjugation to produce antenna effect, resulting in significantly enhancement of the 495 nm emission peak without affecting the 459 nm emission peak. The fluorescence intensity ratio (I495/I459) of CDs-Tb was proportional to the concentration of DPA in the range of 0.5 nM to 2.5 µM with the limit of detection as low as 100 pM. This selective and ultrasensitive assay had a great application prospect in the complex matrixes owing to its simplicity and specificity for DPA. Meanwhile, the CDs-Tb-based paper sensor was successfully developed for sensitive and visual detection of DPA.

Terbium(III) Modified Fluorescent Carbon Dots for Highly Selective and Sensitive Ratiometry of Stringent.

Highly selective and sensitive detection of guanosine 3'-diphosphate-5'-diphosphate (ppGpp), namely, the stringent in plants or microorganisms responding to strict or extreme environmental conditions such as stress and starvation, which plays an important role in gene expression, rRNA and antibiotics production, regulations of virulence of bacteria, and growth of plants, faces a great challenge owing to its extreme similarity to normal nucleotides. By modifying the surface groups of a facile two-step hydrothermal route prepared carbon dots (CDs) with terbium ions (Tb3+) in this contribution, a novel fluorescent probe with excellent properties such as highly physical and chemical stability, narrow emission and excitation wavelength-independent emission was prepared. The Tb3+ ions on the surface of CDs cannot only preserve the intrinsic fluorescence (FL) of CDs but also keep its own coordination capacity with rare earth complex, and thus the clamp structure (four phosphate groups) of ppGpp can specific binding with Tb3+ ions on the surface of CDs to produce antenna effect. Therefore, a highly selective and sensitive fluorescent ratiometry of ppGpp was developed by terbium-modified carbon dots (CDs-Tb) with the limit of detection as low as 50 nM based on the synergistic effect of antenna effect of Tb3+ ions and specific recognition capacity of CDs. The applicability of this assay was demonstrated by CDs-Tb-based paper sensor for high distinguishing ppGpp from other nucleotides with similar structure.

HLA-B*07, HLA-DRB1*07, HLA-DRB1*12, and HLA-C*03:02 Strongly Associate With BMI: Data From 1.3 Million Healthy Chinese Adults.

Strong associations between HLA alleles and infectious and autoimmune diseases are well established. Although obesity is also associated with these diseases, the relationship between HLA and obesity has not been systematically investigated in a large cohort. In the current study, we analyzed the association of HLA alleles with BMI using data from 1.3 million healthy adult donors from the Chinese Marrow Donor Program (CMDP). We found 23 HLA alleles, including 12 low-resolution and 11 high-resolution alleles, were significantly associated with BMI after correction for multiple testing. Alleles associated with high BMI were enriched in haplotypes that were common in both Chinese and European populations, whereas the alleles associated with low BMI were enriched in haplotypes common only in Asians. Alleles B*07, DRB1*07, DRB1*12, and C*03:02 provided the strongest associations with BMI (P = 6.89 × 10-10, 1.32 × 10-9, 1.52 × 10-9, and 4.45 × 10-8, respectively), where B*07 and DRB1*07 also had evidence for sex-specific effects (Pheterogeneity = 0.0067 and 0.00058, respectively). These results, which identify associations between alleles of HLA-B, DRB1, and C with BMI in Chinese young adults, implicate a novel biological connection between HLA alleles and obesity.

Aptamer-modified selenium nanoparticles for dark-field microscopy imaging of nucleolin.

Selenium nanoparticles (SeNPs) with strong green scattering light serving as light scattering nanoprobes for dark-field microscopy imaging are developed for the first time. The SeNPs show good stability, excellent biocompatibility, and high light-producing power, and can precisely and specifically target cancer cells with overexpressed nucleolin (NCL) after modification with aptamers, revealing that the SeNPs can act as a good light scattering nanoprobe for bioimaging and biolabeling.

Self-exothermic reaction prompted synthesis of single-layered graphene quantum dots at room temperature.

The easy fabrication of single-layered graphene quantum dots (s-GQDs) still faces challenge. Herein, we report an efficient route to fabricate s-GQDs within 5 min at room temperature by introducing a simple self-exothermic reaction. The as-prepared s-GQDs can specifically bind with aluminium ions to produce an aggregation-induced emission enhancement effect.

Boron and nitrogen co-doped single-layered graphene quantum dots: a high-affinity platform for visualizing the dynamic invasion of HIV DNA into living cells through fluorescence resonance energy transfer.

High-affinity binding of carbon nanomaterials with nucleobases, which is still a challenge, is the basis for DNA directed assembly and sensing. In this work, boron and nitrogen co-doped single-layered graphene quantum dots (BN-SGQDs) are designed as a high-affinity platform for nucleic acid detection and imaging in living cells, which has been confirmed by density functional theory (DFT) simulation and experiments. Owing to their excellent absorption and photoluminescence ability, the high quantum yield (QY 36.5%) yellow fluorescent BN-SGQDs could act as an energy donor in the fluorescence resonance energy transfer (FRET) process for nucleic acid detection. Furthermore, this BN-SGQD based sensing platform has been successfully adopted to visualize the dynamic invasion of human immunodeficiency virus (HIV) DNA into HeLa cells. The high-affinity platform has shown potential for biosensing in complicated biological samples.

Highly selective and sensitive detection of 2,4,6-trinitrophenol by using newly developed blue-green photoluminescent carbon nanodots.

Though many methods of detecting 2,4,6-trinitrophenol (TNP) mainly have been developed recent years, quantification of TNP in environmental matrixes still faces up to great challenges because all the nitroaromatic explosives reveal highly similar chemical structure. In the present work, we have developed a selective and sensitive method for detection of TNP by amorphous photoluminescent carbon nanodots (CNDs), which are prepared through a simple hydrothermal route using spermine and m-phenylenediamine (MPD) as precursors. The as-prepared CNDs are found to show blue-green photoluminescence, excitation-wavelength independence, and excellent chemical and optical stability. Owing to the strong characteristic absorption of TNP at 356nm (ε=1.048×104cm-1M-1), which has a good spectral overlap with the excitation band of CNDs, the fluorescence intensity of CNDs at 490nm is linearly quenched with the adding concentration of TNP in the range of 0.1-100µM. The developing assay based on inner filter effect (IFE) mechanism for the detection of TNP is selective and convenient, showing that the as-prepared CNDs have applicable prospect in the concept of simplicity and specificity in analytical chemistry.

High-Resolution Analyses of Human Leukocyte Antigens Allele and Haplotype Frequencies Based on 169,995 Volunteers from the China Bone Marrow Donor Registry Program.

Allogeneic hematopoietic stem cell transplantation is a widely used and effective therapy for hematopoietic malignant diseases and numerous other disorders. High-resolution human leukocyte antigen (HLA) haplotype frequency distributions not only facilitate individual donor searches but also determine the probability with which a particular patient can find HLA-matched donors in a registry. The frequencies of the HLA-A, -B, -C, -DRB1, and -DQB1 alleles and haplotypes were estimated among 169,995 Chinese volunteers using the sequencing-based typing (SBT) method. Totals of 191 HLA-A, 244 HLA-B, 146 HLA-C, 143 HLA-DRB1 and 47 HLA-DQB1 alleles were observed, which accounted for 6.98%, 7.06%, 6.46%, 9.11% and 7.91%, respectively, of the alleles in each locus in the world (IMGT 3.16 Release, Apr. 2014). Among the 100 most common haplotypes from the 169,995 individuals, nine distinct haplotypes displayed significant regionally specific distributions. Among these, three were predominant in the South China region (i.e., the 20th, 31st, and 81sthaplotypes), another three were predominant in the Southwest China region (i.e., the 68th, 79th, and 95th haplotypes), one was predominant in the South and Southwest China regions (the 18th haplotype), one was relatively common in the Northeast and North China regions (the 94th haplotype), and one was common in the Northeast, North and Northwest China (the 40th haplotype). In conclusion, this is the first to analyze high-resolution HLA diversities across the entire country of China, based on a detailed and complete data set that covered 31 provinces, autonomous regions, and municipalities. Specifically, we also evaluated the HLA matching probabilities within and between geographic regions and analyzed the regional differences in the HLA diversities in China. We believe that the data presented in this study might be useful for unrelated HLA-matched donor searches, donor registry planning, population genetic studies, and anthropogenesis studies.

[Identification and analysis of the rare HLA-A/B/DRB1 allele genes of 10165 bone marrow registry donors in Shaanxi region].

This study was purposed to analyze the detected status of rare alleles from HLA-A/B/DRB1 typing of 10165 unrelated hematopoietic stem cell donors in Shaanxi region during 2009-2012. The rare allele distributions of HLA-A/B/DRB1 gene typing of 10165 unrelated-donors from Shaanxi sub-registry of Chinese National Marrow Donor Project (CMDP) were detected and analyzed by PCR-SBT. The results showed that there were 40 rare alleles from 48 donors identified by PCR-SBT in 10165 unrelated-donors of Shaanxi sub-registry. Among them, 10 rare alleles of A*02:04, B*07:10, B*27:09, B*35:11, B*44:29, DRB1*03:04, DRB1*08:18, DRB1*13:05, DRB1*13:14 and DRB1*14:11 from 15 donors were not included in the common alleles and well documented alleles (CWD) of China, but were included in the CWD of American Society for Histocompatibility and Immunogenetics (ASHI). The alleles of A*68:24, B*35:11, B*44:29, DRB1*03:04, DRB1*08:18 and DRB1*13:05 were confirmed in more than two samples. There were totally 21 novel HLA alleles identified by our laboratory and officially assigned by the WHO Nomenclature Committee from 2005 to 2012, and some of them were also detected from multiple donors in other HLA typing laboratories of China. Now the novel alleles of HLA-A*02:90, HLA-B*48:14 and HLA-DRB1*01:14 were added into the Chinese CWD list. It is concluded that to ensure the polymorphism integrity and accurate population distribution of HLA genes and its constant accumulations on CMDP, it is necessary to recognize and submit timely the potential novel alleles in our practical work, as well as to record and statistics the identified rare alleles, which can provide the basis for the modification of Chinese CWD. When CWD list is referred, it should be careful for ambiguous results containing the identified rare alleles in order to avoid the occurrence of false or undiscovered detection, and ensure that the patients carrying rare alleles could find a matching donor with the maximum opportunity.

[Analysis of gene polymorphism of HPA and HLA-I in Chinese Xi'an voluntary platelet donors].

To study the allele frequencies and their polymorphism characteristics of human platelet antigen (HPA) and human leucocyte antigen-I (HLA-I) in Chinese xi'an population, the types of HPA and HLA-I in 375 Chinese xi'an voluntary platelet donors were detected by PCR-SSP and PCR-SSO as well as flow cytometry with magnetic beads, and were analyzed. The results showed that there was no polymorphism in HPA-7-HPA-14, HPA-16 and HPA-17 which only expressed-aa type, the -bb type was only detected in HPA-3 and HPA-15, 9 out of 16 samples for the HPA-5ab phenotype simultaneously expressed HPA-15ab, the other 7 samples expressed HPA-15bb, no HPA-15aa phenotype was observed. Phenotypes detected in this study were HPA-1aa-17aa, HPA-1ab, -2ab, -3ab, -3bb, -4ab, -5ab, -6ab, -15ab and -15bb. Among 375 cases, HLA-A specificity of 16 species was observed, which accounted for 76% (16/21) of detectable phenotype specificity in this locus, moreover, 11 species showed frequency > 1%; HLA-B specificity of 36 species was observed which accounted for 84% (36/43) of detectable phenotype specificity in this locus, moreover 23 species showed frequency > 1%, these species were covered by common specific HLA-I in northern China, 264 species haplotype HLA-A-B were found in 375 cases, the frequency of 30 species was > 1%. It is concluded that the gene frequency distribution of HPA and HLA-I in Chinese Xi'an population is in accordance with population of northern China on the whole, but it has its own characteristics.

[Molecular study of two novel RHD alleles and pedigree analysis].

OBJECTIVE: To study the segregation of two novel RHD alleles in Chinese pedigrees. METHODS: The Rh antigens of the samples were identified by using monoclonal antibodies. The 10 exons of the RHD gene for the 2 probands and their family members were amplified separately and sequenced. The parents of proband 2 were analyzed by sequence specific primer-polymerase chain reaction (SSP-PCR). RESULTS: The two probands were RhD negative and the RHD was D/d type. After alignment with the nucleotide sequence in GenBank, a deletion of nucleotide C at position 78 in exon 1 of proband 1 was detected, and her sister also had the deletion, which was confirmed by sequencing. The sequencing results of proband 2 showed a 10 nucleotide deletion in exon 8 as well as a RHD 520 G to A mutation in exon 4. The results of SSP-PCR and sequencing showed that the proband's mother also carried RHD 520 G to A and RHD 1080 del 10 mutation, which was transmitted to proband 2. The sequences of the novel alleles have been submitted to GenBank (accession No. GQ477180 and GU362076). CONCLUSION: The two novel RHD alleles, RHD 78delC and RHD 520 G to A+1080 del 10, were both pseudo genes and stably transmitted.