Site-Recognition-Induced Structural and Photoluminescent Evolution of the Gold-Pincer Nanocluster.

The induced structural transformation provides an efficient way to precisely modulate the fine structures and the corresponding performance of gold nanoclusters, thus constituting one of the important research topics in cluster chemistry. However, the driving forces and mechanisms of these processes are still ambiguous in many cases, limiting further applications. In this work, based on the unique coordination mode of the pincer ligand-stabilized gold nanocluster Au8(PNP)4, we revealed the site-recognition mechanism for induced transformations of gold nanoclusters. The "open nitrogen sites" on the surface of the nanocluster interact with different inducers including organic compounds and metals and trigger the conversion of Au8(PNP)4 to Au13 and Au9Ag4 nanoclusters, respectively. Control experiments verified the site-recognition mechanism, and the femtosecond and nanosecond transient absorption spectroscopy revealed the electronic and photoluminescent evolution accompanied by the structural transformation.

Asymmetric transformation of achiral gold nanoclusters with negative nonlinear dependence between chiroptical activity and enantiomeric excess.

The investigation of chirality at the nanoscale is important to bridge the gap between molecular and macroscopic chirality. Atomically precise metal nanoclusters provide an ideal platform for this research, while their enantiopure preparation poses a challenge. Here, we describe an efficient approach to enantiopure metal nanoclusters via asymmetric transformation, that is, achiral Au23(SC6H11)16 nanoclusters are converted into chiral and enantiopure Au24(L)2(SC6H11)16 nanoclusters by a chiral inducer phosphoramidite (L). Two enantiomers of Au24(L)2(SC6H11)16 are obtained and the crystal structures reveal their hierarchical chirality, which originates from the two introduced chiral L molecules, the transformation-triggered asymmetric rearrangement of the staple motifs on the surface of the gold core, and the helical arrangement of nanocluster molecules. The construction of this type of enantiomerically pure nanoclusters is achieved based on the easy-to-synthesize and modular L. Lastly, the chirality-related chiroptical performance was investigated, revealing a negative nonlinear CD-ee dependence.

Preorganized Nitrogen Sites for Au11 Amidation: A Generalizable Strategy toward Precision Functionalization of Metal Nanoclusters.

Atomically precise metal nanoclusters have received tremendous attention due to their unique structures and properties. Although synthetic approaches to this kind of nanomaterial have been well developed, methods toward precision functionalization of the as-synthesized metal nanoclusters are extremely limited, hindering their interfacial modification and related performance improvement. Herein, an amidation strategy has been developed for the precision functionalization of the Au11 nanocluster based on preorganized nitrogen sites. The nanocluster amidation did not change the number of gold atoms in the Au11 kernel and their bonding mode to the surface ligands but slightly modified the arrangement of gold atoms with the introduction of functionality and chirality, thus representing a relatively mild method for the modification of metal nanoclusters. The stability and oxidation barrier of the Au11 nanocluster are also improved accordingly. The method developed here would be a generalizable strategy for the precision functionalization of metal nanoclusters.

Open Nitrogen Site-Induced Kinetic Resolution and Catalysis of a Gold Nanocluster.

The emerging metal nanocluster provides a platform for the investigation of structural features, unique properties, and structure-property correlation of nanomaterials at the atomic level. Construction of open sites on the surface of the metal nanocluster is a long-pursued but challenging goal. Herein, we realized the construction of "open organic sites" in a metal nanocluster for the first time. Specifically, we introduce the PNP (2,6-bis(diphenylphosphinomethyl)pyridine) pincer ligand in the synthesis of the gold nanocluster, enabling the construction of a structurally precise Au8(PNP)4 nanocluster. The rigidity and the unique bonding mode of PNP lead to open nitrogen sites on the surface of the Au8(PNP)4 nanocluster, which have been utilized as multifunctional sites in this work for efficient kinetic resolution and catalysis. The gold pincer nanocluster and the open nitrogen site-induced performance will be enlightening for the construction of multifunctional metal nanoclusters.

Adsorption of BiOBr microspheres to rhodamine B and its influence on photocatalytic reaction.

Adsorption and its influence are often neglected during photocatalytic degradation of organic pollutants. To call attention to these issues, a novel bismuth oxybromide (BiOBr) microsphere with hierarchical flower-like structure was fabricated through a facile hydrothermal process using polyvinyl pyrrolidone (PVP) as additive in this work, and then the adsorption of the BiOBr microspheres to RhB and its influence on the photocatalytic degradation of RhB were investigated in detail. Experimental results show that the BiOBr microspheres have a very strong adsorption capacity to RhB. The adsorption behavior follows the Langmuir model and the quasi second order kinetic equation. Tests of the photocatalytic degradation of RhB under visible irradiation verify that the adsorption of the BiOBr microspheres to RhB greatly boosts the degradation of RhB due to the "enriching effect", and a complete degradation of 20 mg L-1 RhB only requires 37 min.

Transmitted antiretroviral drug resistance and thumb subdomain polymorphisms among newly HIV type 1 diagnosed patients infected with CRF01_AE and CRF07_BC virus in Guangdong Province, China.

The aim of this study was to elucidate the prevalence of transmitted drug-resistant (TDR) mutations and reverse transcriptase (RT) thumb subdomain polymorphisms in CRF01_AE and CRF07_BC virus among newly diagnosed, therapy-naive HIV-1 patients in Guangdong Province, China. One hundred and sixty-four samples were collected in the Guangzhou Eighth People's Hospital. The entire protease gene and 300 codons of the entry part of the reverse transcriptase were amplified and sequenced. Furthermore, genotypic drug resistance, polymorphisms, and their phylogeny were analyzed. According to eligibility criteria, seven samples were excluded, and 119 of 157 (75.8%) samples (84 CRF01_AE and 35 CRF07_BC) were amplified and sequenced successfully. The prevalence of TDR identified in the present study was 6.7% [8/119, 95% confidence interval (CI) 1.8-11.6%]. Three major resistance mutations, K103N, M184V, and Y188L, each of which caused more than one drug resistance, appeared in only two patients; the prevalence [1.7 % (2/119)] was relatively low. Until now, this is the first observation of the five newly identified accessory mutations, V35T, K43E, V60I, K122E, and E203D, and seven thumb subdomain polymorphisms, A272P, K277R, K281R, T286A, E291D, V292I, and I293V, in the RT gene in China. These findings provide useful information for guidance on the antiretroviral therapy (ART) policy in China where therapeutic options are still limited.

[A novel method for hepatitis C virus genotyping using RT-PCR reverse dot blot hybridization technique].

OBJECTIVE: To develop a rapid and specific method for hepatitis C virus ( HCV) genotyping using reverse dot blot hybridization technique and investigate the distribution of HCV genotypes and subtypes in Guangdong. METHODS: The primers and the probes targeting the 5'untranslated region (5'UTR) and core region of HCV genotypes 1b, 2a, 3a, 3b and 6a were designed, and the RT-PCR reverse dot blot hybridization (PCR-RDH) method for HCV genotyping was established. A total of 115 patients with hepatitis C were genotyped using this method, and 38 of them were also genotyped by sequencing and phylogenetic analysis to evaluate the accuracy and specificity of the method. RESULTS: Of the 115 patients, 111 were successfully genotyped to be 1b, 2a, 3a, 3b, 6a and mix-infection of 1b/2a at frequencies of 56.8%, 8.1 %, 3.6%, 5.4%, 25.2% and 0.9% respectively, and all the 15 healthy control samples showed negative results. The accuracy and reliability of the genotyping method of PCR-RDH was confirmed in 38 cases by amplification of HCV core and NS5B regions followed by DNA sequencing and phylogenetic analysis. CONCLUSION: This method for HCV genotyping, with high reliability and specificity, is suitable for clinical and epidemiological investigations. The prevalence of HCV genotypes 1b and 2a decreases while 1b remains the dominant genotype in Guangdong, where the prevalence of 6a significantly increases as compared with that 10 years ago.

Relationship between apolipoprotein E, D10S1225 polymorphisms and late-onset Alzheimer's disease.

BACKGROUND: There were some papers published in the Jonrnal of Science, December 2000 suggesting that one or more important susceptibility genes for late onset Alzheimer's disease (LOAD) were located on the long arm of chromosome 10. Linkage analysis showed maximum lod score close to D10S1225 loci, which indicated the loci might contribute to the etiology of Alzheimer's disease (AD). METHODS: Fifty-nine LOAD patients and 107 controls were recruited. Apolipoprotein E (ApoE) genotypes were determined by reverse dot blotting hybridization assay. The D10S1225 was genotyped by 12% nondenaturing polyacrylamide gels electrophoresis and analyzed by silver staining. Statistical analysis was used to compare genotype and allele distributions between LOAD group and control group for ApoE and D10S1225 polymorphisms. RESULTS: ApoE epsilon 4 was significantly higher in LOAD group in comparison with the control group (chi(2) = 6.530, P = 0.011). Seven different alleles of D10S1225 have been identified. The length of these gene fragments were 178 bp, 181 bp, 184 bp, 187 bp, 190 bp, 193 bp, and 196 bp, respectively. A total of 21 different genotypes were observed. There was no relationship between D10S1225 polymorphism and LOAD (chi(2) = 4.488, P > 0.05). Conclusion This study suggests that ApoE epsilon 4 is a risk factor for LOAD, however, the results indicated that there is not any possible linkage for disequilibria with a nearby AD risk gene near D10S1225.