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1.
ACS Appl Mater Interfaces ; 13(33): 39711-39718, 2021 Aug 25.
Artigo em Inglês | MEDLINE | ID: mdl-34402304

RESUMO

The manufacture of DNA origami nanostructures with highly ordered functional motifs is of great significance for biomedical applications. Here, we present a robust strategy to produce customized scaffolds with integrated aptamer sequences, which enables direct construction of functional DNA origami structures. As we demonstrated, aptamers of various numbers and types were efficiently and stably integrated in user-defined positions of the scaffolds. Specifically, two different thrombin aptamer sequences were simultaneously inserted into the M13mp18 phage genome. The assembled functional DNA origami structures from this aptamer-integrated scaffold exhibited increased binding efficiency to thrombin and displayed more than 10-fold stronger resistance to exonuclease degradation than that produced using the traditional staple extension method. Additionally, a scaffold integrated with the platelet-derived growth factor aptamer was produced, and the assembled DNA origami structures showed significant inhibitory effect on breast cancer cells MDA-MB-231. This scalable method of creating design-specific scaffolds opens up a new way to construct more stable and functionally robust DNA origami structures and thus provides an important basis for their broader applications.


Assuntos
Aptâmeros de Nucleotídeos/química , Aptâmeros de Nucleotídeos/metabolismo , DNA/química , Nanoestruturas/química , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Humanos , Conformação de Ácido Nucleico , Trombina/química
2.
Anal Chem ; 93(9): 4317-4325, 2021 03 09.
Artigo em Inglês | MEDLINE | ID: mdl-33620193

RESUMO

Poor antimatrix interference capability of aptamers is one of the major obstacles preventing their wide applications for real-sample detections. Here, we devise a multiple-function interface, denoted as a nanoscale affinity double layer (NADL), to overcome this bottleneck via in situ simultaneous target enrichment, purification, and detection. The NADL consists of an upper aptamer layer for target purification and sensing and a lower nanoscale solid-phase microextraction (SPME) layer for sample enrichment. The targets flowing through the NADL-functionalized surface are instantly million-fold enriched and purified by the sequential extraction of aptamer and SPME. The formation of the aptamer-target complex is greatly enhanced, enabling ultrasensitive detection of targets with minimized interference from the matrix. Taking the fiber-optic evanescent wave sensor as an example, we demonstrated the feasibility and generality of the NADL. The unprecedented detection of limits of 800, 4.8, 40, and 0.14 fM were, respectively, achieved for three representative small-molecule targets with distinct hydrophobicity (kanamycin A, sulfadimethoxine, and di-(2-ethylhexyl) phthalate) and protein target (human serum albumin), corresponding to 2500 to 3 × 108-fold improvement compared to the sensors without the NADL. Our sensors also showed exceptionally high target specificity (>1000) and tunable dynamic ranges simply by manipulating the SPME layer. With these features comes the ability to directly detect targets in diluted environmental, food, and biological samples at concentrations all well below the tolerance limits.

3.
Artigo em Inglês | MEDLINE | ID: mdl-32121500

RESUMO

The quality and scale of urbanization development are the two main aspects in China's current urbanization process. By measuring and analyzing the level differences in these two aspects, the healthy development of China's urbanization and urban-rural integration will be promoted. Based on the quality of urbanization and the scale of urbanization, this paper constructs an evaluation index system for urbanization coordination level. On this basis, this paper analyzes the spatial correlation, spatial difference, and spatial pattern evolution characteristics of urbanization coordination level in 286 sample cities nationwide from 2005 to 2015. Then, by introducing the spatial econometric regression model, this paper discusses the driving mechanism of the spatial and temporal evolution of urbanization coordination level. The results show that: (1) The level of coordination between urbanization quality and urbanization scale shows a strong spatial correlation in space, which is consistent with the actual development status; (2) the level of urbanization coordination shows a trend of evolution from northeast to southwest in the evolution of spatial pattern, but the extent of change is small; and (3) the spatial and temporal pattern of urbanization coordination level is affected by different driving forces, of which internal source is the primary impact factor, followed by administrative level and investment level. In addition, the level of urbanization coordination has a positive spillover effect on the level of urbanization coordination in adjacent areas.


Assuntos
Desenvolvimento Sustentável/tendências , Urbanização/tendências , China , Cidades , Modelos Econométricos , Análise Espaço-Temporal
4.
J Vis Exp ; (133)2018 03 21.
Artigo em Inglês | MEDLINE | ID: mdl-29630049

RESUMO

Phthalic acid esters (PAEs) areone of the major groups of persistent organic pollutants. The group-specific detection of PAEs is highly desired due to the rapid growing of congeners. DNA aptamers have been increasingly applied as recognition elements on biosensor platforms, but selecting aptamers toward highly hydrophobic small molecule targets, such as PAEs, is rarely reported. This work describes a bead-based method designed to select group-specific DNA aptamers to PAEs. The amino group functionalized dibutyl phthalate (DBP-NH2) as the anchor target was synthesized and immobilized on the epoxy-activated agarose beads, allowing the display of the phthalic ester group at the surface of the immobilization matrix, and therefore the selection of the group-specific binders. We determined the dissociation constants of the aptamer candidates by quantitative polymerization chain reaction coupled with magnetic separation. The relative affinities and selectivity of the aptamers to other PAEs were determined by the competitive assays, where the aptamer candidates were pre-bounded to the DBP-NH2 attached magnetic beads and released to the supernatant upon incubation with the tested PAEs or other potential interfering substances. The competitive assay was applied because it provided a facile affinity comparison among PAEs that had no functional groups for surface immobilization. Finally, we demonstrated the fabrication of an electrochemical aptasensor and used it for ultrasensitive and selective detection of bis(2-ethylhexyl) phthalate. This protocol provides insights for the aptamer discovery of other hydrophobic small molecules.


Assuntos
Aptâmeros de Nucleotídeos/química , Técnicas Biossensoriais/métodos , Ésteres/metabolismo , Ácidos Ftálicos/metabolismo
5.
Biosens Bioelectron ; 110: 162-167, 2018 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-29609164

RESUMO

The type A influenza viruses are the most virulent and variable human pathogens with epidemic or even pandemic threat. The development of sensitive, specific and safe field testing methods is in particular need and quite challenging. We report here the selection and practical utilization of the inactivated influenza virus-specific aptamers. The DNA aptamers against inactivated intact H1N1 virus particles were identified through the systematic evolution of ligands by exponential enrichment (SELEX) procedure. The discriminative aptamers and their truncated sequences showed selectively high affinity to inactive H1N1 virus and H3N2 virus with the Kd in the low nanomolar range and collective binding properties. The truncated sequences were first applied in a sandwich enzyme-linked oligonucleotide assay (ELONA) with a H1N1 detection limit (LOD, S/N = 3) of 0.3 ng/µL and then in an electrochemical impedance (EIS) aptasensor with more than 300 times improved LOD (0.9 pg/µL) and the excellent selectivity over other viruses (> 100 times). Therefore the developed aptasensors represent the safer, simpler, and possibly better virus-variation adaptable means of virus diagnostics.


Assuntos
Aptâmeros de Nucleotídeos/química , Técnicas Biossensoriais/métodos , Vírus da Influenza A Subtipo H1N1/isolamento & purificação , Influenza Humana/virologia , Técnica de Seleção de Aptâmeros/métodos , Impedância Elétrica , Técnicas Eletroquímicas/métodos , Humanos , Influenza Humana/diagnóstico , Limite de Detecção
6.
Anal Chem ; 89(10): 5270-5277, 2017 05 16.
Artigo em Inglês | MEDLINE | ID: mdl-28414217

RESUMO

Phthalic acid esters (PAEs) are ubiquitous in the environment, and some of them are recognized as endocrine disruptors that cause concerns on ecosystem functioning and public health. Due to the diversity of PAEs in the environment, there is a vital need to detect the total concentration of PAEs in a timely and low-cost way. To fulfill this requirement, it is highly desired to obtain group-specific PAE binders that are specific to the basic PAE skeleton. In this study, for the first time we have identified the group-specific PAE-binding aptamers via rationally designed target immobilization. The two target immobilization strategies were adopted to display either the phthalic ester group or the alkyl chain, respectively, at the surface of the immobilization matrix. The former enabled the rapid enrichment of aptamers after four rounds of selection. The top 100 sequences are cytosine-rich (44.7%) and differentiate from each other by only 1-4 nucleotides at limited locations. The top two aptamers all display the nanomolar dissociation constants to both the immobilized target and the free PAEs [dibutyl phthalate (DBP), butyl benzyl phthalate (BBP), bis(2-ethylhexyl) phthalate (DEHP)]. We further demonstrate the applications of the aptamers in the development of high-throughput PAE assays and DEHP electrochemical biosensors with exceptional sensitivity [limit of detection (LOD), 10 pM] and selectivity (>105-fold). PAE aptamers targeting one of the most sought for targets thus offer the promise of convenient, low-cost detection of total PAEs. Our study also provides insights on the aptamer selection and sensor development of highly hydrophobic small molecules.


Assuntos
Aptâmeros de Nucleotídeos/química , Técnicas Biossensoriais/métodos , Ácidos Ftálicos/análise , Dibutilftalato/análise , Dietilexilftalato/análise , Técnicas Eletroquímicas , Disruptores Endócrinos/análise , Ésteres/química , Imobilização , Ácidos Nucleicos Imobilizados/química , Cinética , Microscopia de Fluorescência
7.
Environ Manage ; 55(2): 467-78, 2015 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-25421995

RESUMO

The impact of land-use change on greenhouse gas emissions has become a core issue in current studies on global change and carbon cycle. However, a comprehensive evaluation of the effects of land-use changes on carbon emissions is very necessary. This paper attempted to apply the Grossman decomposition model to estimate the scale, structural, and management effects of land-use carbon emissions based on final energy consumption by establishing the relationship between the types of land use and carbon emissions in energy consumption. It was shown that land-use carbon emissions increase from 169.5624 million tons in 2000 to 637.0984 million tons in 2010, with an annual average growth rate of 14.15%. Meanwhile, land-use carbon intensity increased from 17.59 t/ha in 2000 to 64.42 t/ha in 2010, with an average annual growth rate of 13.86%. The results indicated that rapid industrialization and urbanization in Zhejiang Province promptly increased urban land and industrial land, which consequently affected land-use extensive emissions. The structural and management effects did not mitigate land-use carbon emissions. By contrast, both factors evidently affected the growth of carbon emissions because of the rigid demands of energy-intensive land-use types and the absence of land management. Results called for the policy implications of optimizing land-use structures and strengthening land-use management.


Assuntos
Ar/análise , Dióxido de Carbono/análise , China , Monitoramento Ambiental , Efeito Estufa , Indústrias , Modelos Teóricos , Urbanização
8.
Ying Yong Sheng Tai Xue Bao ; 20(7): 1759-64, 2009 Jul.
Artigo em Chinês | MEDLINE | ID: mdl-19899482

RESUMO

By using RS and GIS techniques, the spatiotemporal changes of wetlands in Hangzhou Bay Industrial Belt, one of the most developed zones in Zhejiang Province, from 1990 to 2005 were studied. There was a frequent conversion between the wetlands and other land use types and between the wetlands themselves, mainly manifested in the conversion between wetland and farmland, and from wetland to construction land and from tidal flat to aquiculture area. The comparative advantage of other land use types and the policy of cultivated land's requisition-compensation balance decided the inherent mechanisms of these spatiotemporal changes. Driven by the aquaculture's comparative advantage to traditional agriculture, large areas of inland farmland and of the tidal flat along the coast of Hangzhou Bay were reclaimed into aquiculture area, and the rapid expansion of construction land, limited land resources, and the implement of cultivated land's requisition-compensation balance policy induced the wetlands being occupied.


Assuntos
Conservação dos Recursos Naturais , Produtos Agrícolas/crescimento & desenvolvimento , Monitoramento Ambiental/métodos , Urbanização , Áreas Alagadas , China , Sistemas de Informação Geográfica , Comunicações Via Satélite
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