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1.
ACS Appl Mater Interfaces ; 13(33): 38931-38946, 2021 Aug 25.
Artigo em Inglês | MEDLINE | ID: mdl-34374513

RESUMO

With the continuous development of DNA nanotechnology, various spatial DNA structures and assembly techniques emerge. Hybridization chain reaction (HCR) is a typical example with exciting features and bright prospects in biosensing, which has been intensively investigated in the past decade. In this Spotlight on Applications, we summarize the assembly principles of conventional HCR and some novel forms of linear/nonlinear HCR. With advantages like great assembly kinetics, facile operation, and an enzyme-free and isothermal reaction, these strategies can be integrated with most mainstream reporters (e.g., fluorescence, electrochemistry, and colorimetry) for the ultrasensitive detection of abundant targets. Particularly, we select several representative studies to better illustrate the novel ideas and performances of HCR strategies. Theoretical and practical utilities are confirmed for a range of biosensing applications. In the end, a deep discussion is provided about the challenges and future tasks of this field.


Assuntos
DNA/química , Técnicas Biossensoriais , Colorimetria , Técnicas Eletroquímicas , Humanos , Nanopartículas/química , Técnicas de Amplificação de Ácido Nucleico/métodos , Conformação de Ácido Nucleico , Hibridização de Ácido Nucleico/métodos , Sensibilidade e Especificidade , Espectrometria de Fluorescência
2.
Analyst ; 146(18): 5610-5618, 2021 Sep 13.
Artigo em Inglês | MEDLINE | ID: mdl-34378564

RESUMO

The rapid development of industrial technologies continuously increases the heavy metal pollution of water resources. Recently, portable electrochemical analysis-based devices for detecting heavy metal ions have attracted much attention due to their excellent performance and low fabrication costs. However, it has proven difficult to accommodate complex testing needs in a cost-effective manner. To address these limitations, we propose a new system for the in situ detection of heavy metals in wastewater using an organic light-emitting diode-based panel to display data in real time and Bluetooth to transmit data to a smartphone for rapid analysis. The fabricated device integrates an in situ signal analysis circuit, a Bluetooth chip, a photocured 3D-printed shell, and an electrode sleeve interface. In addition, a fully screen-printed functional electrode plate containing chitosan/PANi-Bi nanoparticle@graphene oxide multi-walled carbon nanotubes is utilized for the rapid detection of heavy metal ions. This device can perform wireless data transmission and analysis and in situ signal acquisition and processing. The sensor exhibits a high sensitivity (Hg2+: 88.34 µA ppm-1 cm-2; Cu2+: 0.956 µA ppm-1 cm-2), low limit of detection (Hg2+: 10 ppb, Cu2+: 0.998 ppm) and high selectivity during the detection of copper and mercury ions in tap water under non-laboratory conditions, and the results of real-time tests reveal that parameters measured in the field and laboratory environments are identical. Hence, this small, portable, electrochemical sensor with a screen-printed electrode can be effectively used for the real-time detection of copper and mercury ions in complex water environments.


Assuntos
Metais Pesados , Nanotubos de Carbono , Eletrodos , Íons , Esgotos
3.
BMC Ophthalmol ; 21(1): 150, 2021 Mar 25.
Artigo em Inglês | MEDLINE | ID: mdl-33765984

RESUMO

BACKGROUND: Strabismus is the leading risk factor for amblyopia, which should be early detected for minimized visual impairment. However, traditional school screening for strabismus can be challenged due to several factors, most notably training, mobility and cost. The purpose of our study is to evaluate the feasibility of using a smartphone application in school vision screening for detection of strabismus. METHODS: The beta smartphone application, EyeTurn, can measure ocular misalignment by computerized Hirschberg test. The application was used by a school nurse in a routine vision screening for 133 elementary school children. All app measurements were reviewed by an ophthalmologist to assess the rate of successful measurement and were flagged for in-person verification with prism alternating cover test (PACT) using a 2.4Δ threshold (root mean squared error of the app). A receiver operating characteristic (ROC) curve was used to determine the best sensitivity and specificity for an 8Δ threshold (recommended by AAPOS) with the PACT measurement as ground truth. RESULTS: The nurse obtained at least one successful app measurement for 93% of children (125/133). 40 were flagged for PACT, of which 6 were confirmed to have strabismus, including 4 exotropia (10△, 10△, 14△ and 18△), 1 constant esotropia (25△) and 1 accommodative esotropia (14△). Based on the ROC curve, the optimum threshold for the app to detect strabismus was determined to be 3.0△, with the best sensitivity (83.0%), specificity (76.5%). With this threshold the app would have missed one child with accommodative esotriopia, whereas conventional screening missed 3 cases of intermittent extropia. CONCLUSIONS: Results support feasibility of use of the app by personnel without professional training in routine school screenings to improve detection of strabismus.


Assuntos
Ambliopia , Aplicativos Móveis , Estrabismo , Ambliopia/diagnóstico , Criança , Humanos , Instituições Acadêmicas , Smartphone , Estrabismo/diagnóstico
4.
ACS Omega ; 5(32): 20100-20106, 2020 Aug 18.
Artigo em Inglês | MEDLINE | ID: mdl-32832764

RESUMO

Bio-optical imaging can noninvasively describe specific biochemical reaction events in small animals using endogenous or exogenous imaging reagents to label cells, proteins, or DNA. The fluorescence optical bio-imaging system excites the fluorescent group to a high energy state by excitation light and then generates emission light. However, many substances in the organism will also emit fluorescence after being excited by the excitation light, and the nonspecific fluorescence generated will affect the detection sensitivity. This paper designs and develops a set of high-level biosafety in vivo fluorescence imaging system for small animals suitable for virology research and proposes a target area extraction algorithm for fluorescence images. The fluorescence image target extraction algorithm first maps the nonlinear separation data in the low-dimensional space to the high-dimensional space. Then, based on the analysis of the characteristics of the fluorescent region, a method for discriminating the target fluorescent region based on the two-step entropy function is proposed, and the real target fluorescent region is obtained according to the set connected region. Based on the experiment of collecting and analyzing the in vivo fluorescent images of mice, it is verified that the proposed algorithm can automatically extract the target fluorescent region better than the classical linear model. It shows that the proposed algorithm is less affected by background fluorescence, and the estimated separated spectrum based on this method is closer to the real target spectrum.

5.
ACS Appl Mater Interfaces ; 12(26): 29218-29227, 2020 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-32490658

RESUMO

Performance degradation of lithium/sodium-ion capacitors (LICs/SICs) mainly originates from anode pulverization, particularly the alloying and conversion types, and has spurred research for alternatives with an insertion mechanism. Three-dimensional (3D) topotactic host materials remain much unexplored compared to two-dimensional (2D) ones (graphite, etc.). Herein, vanadium monophosphide (VP) is designed as a 3D topotactic host anode. Ex situ electrochemical characterizations reveal that there are no phase changes during (de)intercalation, which follows the topotactic intercalation mechanism. Computational simulations also confirm the metallic feature and topotactic structure of VP with a spacious interstitial position for the accommodation of guest species. To boost the electrochemical performance, carbon nano-onions (CNOs) are coupled with 3D VP. Superior specific capacity and rate capability of VP-CNOs vs lithium/sodium can be delivered due to the fast ion diffusion nature. An exceptional capacity retention of above 86% is maintained after 20 000 cycles, benefitting from the topotactic intercalation process. The optimized LICs/SICs exhibit high energy/power densities and an ultrastable lifespan of 20 000 cycles, which outperform most of the state-of-the-art LICs and SICs, demonstrating the potential of VP-CNOs as insertion anodes. This exploration would draw attention with regard to insertion anodes with 3D topotactic host topology and provide new insights into anode selection for LICs/SICs.

6.
Invest Ophthalmol Vis Sci ; 61(5): 55, 2020 05 11.
Artigo em Inglês | MEDLINE | ID: mdl-32460319

RESUMO

Purpose: To investigate the differential expression of cytokines and growth factors in the cornea and aqueous humor after small incision lenticule extraction (SMILE) compared with femtosecond LASIK (FS-LASIK) using rabbit model. Methods: Sixteen eyes of 16 rabbits in each group underwent SMILE or FS-LASIK with refractive correction of -6.00 DS/-1.00 DC. Eight additional rabbits served as controls. Pre- and 24 hours, 1 week, 1 month, and 3 months postoperatively, slit-lamp and anterior segment optical coherence tomography were performed, followed by cornea and aqueous humor collection. Apoptosis and proliferation were evaluated with TUNEL assay and Ki-67 immunostaining, respectively. The mRNA and protein expression of cytokines and growth factors was determined by RT-qPCR and Western blotting, respectively. Cytokine levels in the aqueous humor were detected with ELISA. Results: Compared with FS-LASIK, SMILE induced less apoptosis and proliferation in the cornea within 1 week postoperatively. Levels of IL-1ß, TNF-α, and EGFR in the cornea were significantly increased after FS-LASIK compared with SMILE within 24 hours. Levels of IL-8 in the aqueous humor remained elevated until 1 week after FS-LASIK but not SMILE. TGF-ß1 level was elevated up to 1 month after both procedures, while BFGF level was kept high within 1 month after SMILE but not FS-LASIK. Conclusions: SMILE could induce significantly less acute inflammation than FS-LASIK in the cornea and aqueous humor. The differential expression of TGF-ß1 and BFGF between two procedures until 1 month might contribute to the post-SMILE delayed recovery and underline the importance of continued treatment postoperatively.


Assuntos
Humor Aquoso/metabolismo , Córnea/metabolismo , Córnea/cirurgia , Citocinas/biossíntese , Peptídeos e Proteínas de Sinalização Intercelular/biossíntese , Ceratomileuse Assistida por Excimer Laser In Situ , Procedimentos Cirúrgicos Refrativos , Animais , Feminino , Período Pós-Operatório , Coelhos , Procedimentos Cirúrgicos Refrativos/métodos , Fatores de Tempo
7.
Zhongguo Yi Liao Qi Xie Za Zhi ; 44(1): 7-12, 2020 Jan 08.
Artigo em Chinês | MEDLINE | ID: mdl-32343058

RESUMO

This study proposes an image segmentation method based on bottleneck detection and watershed algorithm to solve the problem of overlapping cervical cell image. First, we use polygon approximation to get all feature points on the cell contour and then use bottleneck detection and ellipse fitting to obtain the correct split point pairs. Therefore, the approximate range of the overlapping region was determined. The watershed algorithm was used to obtain the internal boundary information for the gradient image of the region. Finally, the segmentation results of the overlapped cells were obtained by superimposing with the outer contour. The experimental results show that this algorithm can segment the contour of a single cell from the overlapping cervical cell images with good accuracy and integrity. The segmentation result is close to that of doctors' manual marking, and the segmentation result is better than other existing algorithms.


Assuntos
Algoritmos , Colo do Útero/citologia , Processamento de Imagem Assistida por Computador , Feminino , Humanos
8.
Nat Commun ; 10(1): 3048, 2019 07 11.
Artigo em Inglês | MEDLINE | ID: mdl-31296855

RESUMO

Bacteriophages typically hijack the host bacterial transcriptional machinery to regulate their own gene expression and that of the host bacteria. The structural basis for bacteriophage protein-mediated transcription regulation-in particular transcription antitermination-is largely unknown. Here we report the 3.4 Å and 4.0 Å cryo-EM structures of two bacterial transcription elongation complexes (P7-NusA-TEC and P7-TEC) comprising the bacteriophage protein P7, a master host-transcription regulator encoded by bacteriophage Xp10 of the rice pathogen Xanthomonas oryzae pv. Oryzae (Xoo) and discuss the mechanisms by which P7 modulates the host bacterial RNAP. The structures together with biochemical evidence demonstrate that P7 prevents transcription termination by plugging up the RNAP RNA-exit channel and impeding RNA-hairpin formation at the intrinsic terminator. Moreover, P7 inhibits transcription initiation by restraining RNAP-clamp motions. Our study reveals the structural basis for transcription antitermination by phage proteins and provides insights into bacterial transcription regulation.


Assuntos
Proteínas de Bactérias/metabolismo , Bacteriófagos/genética , Fatores de Elongação da Transcrição/metabolismo , Proteínas Virais/metabolismo , Xanthomonas/genética , Proteínas de Bactérias/isolamento & purificação , Proteínas de Bactérias/ultraestrutura , Microscopia Crioeletrônica , RNA Polimerases Dirigidas por DNA/isolamento & purificação , RNA Polimerases Dirigidas por DNA/metabolismo , RNA Polimerases Dirigidas por DNA/ultraestrutura , Regulação Bacteriana da Expressão Gênica , Regulação Viral da Expressão Gênica , Interações entre Hospedeiro e Microrganismos/genética , Oryza/microbiologia , Estrutura Secundária de Proteína , Proteínas Recombinantes/isolamento & purificação , Proteínas Recombinantes/metabolismo , Proteínas Recombinantes/ultraestrutura , Regiões Terminadoras Genéticas/genética , Transcrição Genética , Fatores de Elongação da Transcrição/isolamento & purificação , Fatores de Elongação da Transcrição/ultraestrutura , Proteínas Virais/isolamento & purificação , Proteínas Virais/ultraestrutura , Xanthomonas/virologia
9.
Anal Chem ; 91(15): 9940-9945, 2019 08 06.
Artigo em Inglês | MEDLINE | ID: mdl-31246440

RESUMO

Herein we describe a novel isothermal and enzyme-free electrochemical aptasensor for protein detection via the employment of polymeric ferrocene nanoparticles (PFcNPs) and target-catalyzed hairpin assembly amplification. The synthesized PFcNPs not only load numerous Fc molecules for enhanced electrochemical output but also possess plenty of amino groups, which increase the water solubility and facilitate the conjugation with the aptamer toward the recognition of target protein. After the formation of an aptamer/protein complex, the conformation of the DNA probe changes, which further triggers hairpin assembly on top of DNA tetrahedral structures modified on the electrode interface. The process can be recycled, and multiple PFcNPs are localized on the electrode. Thus, an amplified electrochemical signal is able to be recorded, which is sufficient to achieve a demonstrated limit of detection as low as 67 fM. This developed aptasensor can also discriminate target protein from other interfering substances with a high selectivity. Furthermore, it has been successfully applied in diluted real blood serum samples. All of these features make the present methodology a promising candidate for ultratrace protein biosensors.


Assuntos
Compostos Ferrosos/química , Metalocenos/química , Nanopartículas/química , Proteínas/análise , Catálise , DNA/química , DNA/metabolismo , Técnicas Eletroquímicas/métodos , Eletrodos , Humanos , Imunoglobulina G/análise , Imunoglobulina G/metabolismo , Limite de Detecção , Ligação Proteica , Proteínas/metabolismo , Trombina/análise , Trombina/metabolismo
10.
Int Ophthalmol ; 39(8): 1827-1836, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-30171445

RESUMO

PURPOSE: To evaluate the three-dimensional corneal spatial profiles following small incision lenticule extraction (SMILE) based on corneal asphericity, thickness, and volume. MATERIALS AND METHODS: Eighty-three eyes in 83 patients who underwent SMILE were examined before and 1 and 6 months after surgery. The asphericity of the anterior and posterior corneal surfaces was analyzed. Corneal volume (CV) was measured in corneal regions measuring 3.0 mm, 5.0 mm, and 7.0 mm in diameter. Mean corneal thickness (CT) values were acquired at the apex (0.0 mm) and in four concentric radial zones from the apex (with diameters of 2.0, 4.0, 6.0, and 8.0 mm). RESULTS: The mean anterior Q value increased from - 0.32 preoperatively to 0.67 at 1 month and 0.62 at 6 months postoperatively. The mean posterior Q value decreased from - 0.30 preoperatively to - 0.26 at 1 month and to - 0.25 at 6 months postoperatively. The CV increased by 0.05 ± 0.06 mm3 (1.40%), 0.06 ± 0.11 mm3 (0.83%), and 0.09 ± 0.17 mm3 (0.73%) along the radial zones with respective diameters of 3.0 mm, 5.0 mm, and 7.0 mm. The CT increased by 6.02 ± 6.48 µm (1.36%) at the apex and then decreased with increasing distance from the center, i.e., to 5.52 ± 6.31 µm (1.20%) at 2.0 mm, 4.72 ± 6.55 µm (0.92%) at 4.0 mm, 4.47 ± 7.86 µm (0.75%) at 6.0 mm, and 4.86 ± 10.31 µm (0.70%) at 8.0 mm. No correlations were observed between changes in CV and CT and refractive fluctuation between 1 month and 6 months postoperatively. CONCLUSIONS: The corneal profile displayed a less oblate shift on the anterior surface; however, the posterior surface showed a slight backward shift during the postoperative period. The CV and CT steadily increased after surgery and mainly within the operative zones. Refraction remained stable postoperatively and was not affected by the corneal remodeling.


Assuntos
Córnea/diagnóstico por imagem , Cirurgia da Córnea a Laser/métodos , Miopia/cirurgia , Refração Ocular/fisiologia , Adolescente , Adulto , Córnea/fisiopatologia , Substância Própria/diagnóstico por imagem , Substância Própria/fisiopatologia , Substância Própria/cirurgia , Feminino , Seguimentos , Humanos , Masculino , Miopia/diagnóstico , Miopia/fisiopatologia , Período Pós-Operatório , Estudos Prospectivos , Fatores de Tempo , Acuidade Visual , Adulto Jovem
11.
ACS Omega ; 3(9): 12141-12146, 2018 Sep 30.
Artigo em Inglês | MEDLINE | ID: mdl-30320290

RESUMO

Urine strips are widely applied for rapid analysis of various indexes of urine for clinical examinations. The tests mainly rely on the application of a urine analyzer, which suffers several drawbacks and cannot meet the requirements of point-of-care testing (POCT). The integration of a smartphone with a biosensor has recently attracted great attention. We herein propose a human vision-based smartphone algorithm for colorimetric analysis of various urine indexes. A CIEDE2000 formula in CIELab color space is applied for the evaluation of color difference, which may greatly improve the analytical performances of urine strips. The proposed algorithm also possesses merits such as good accuracy, quantitative analysis, and limited calculation task, which is suitable for the application with smartphone platform. Experimental results demonstrate that the proposed method shows excellent reliability compared with the urine analyzer and some other algorithms. In addition, human real samples are successfully analyzed with excellent accuracy. Therefore, this work provides a convenient colorimetric tool for POCT urine analysis.

12.
Analyst ; 143(22): 5352-5357, 2018 Nov 05.
Artigo em Inglês | MEDLINE | ID: mdl-30283926

RESUMO

miRNAs are novel diagnostic and prognostic biomarkers for a diversity of diseases like cancers. In this study, an ultrasensitive electrochemical biosensor for miRNA evaluation is fabricated. A methylene blue (MB) labeled DNA probe is firstly modified on a gold electrode. By employing target induced strand displacement amplification and subsequent DNAzyme cleavage cycles, a large number of MB molecules are released. The decreased oxidation peak current could be used to reveal the miRNA concentration. Based on the two efficient signal amplifications, this method shows ultrahigh sensitivity. Its feasibility for the analysis of miRNA in cell lysates is also demonstrated. Therefore, the method shows attractive potential for promising applications in early diagnosis of certain diseases.


Assuntos
Sondas de DNA/química , DNA Catalítico/química , MicroRNAs/análise , Técnicas Biossensoriais/métodos , Linhagem Celular Tumoral , Sondas de DNA/genética , DNA Catalítico/genética , Técnicas Eletroquímicas/métodos , Humanos , Limite de Detecção , Azul de Metileno/química , Técnicas de Amplificação de Ácido Nucleico/métodos , Polimerização
13.
Mar Drugs ; 16(11)2018 Oct 23.
Artigo em Inglês | MEDLINE | ID: mdl-30360574

RESUMO

Five new acylated aminooligosaccharides (1⁻5), together with one known related analogue (6), were isolated from Streptomyces sp. HO1518. Their structure was identified by extensive spectroscopic analysis, including 1D and 2D NMR data and high resolution electrospray ionization mass spectrometry (HRESIMS), and by comparison with those reported in the literature. All of the new compounds showed more promising porcine pancreatic α-amylase (PPA) inhibitory activities than the clinical drug acarbose, indicating them as potential pharmaceutical drug leads toward type II diabetes.


Assuntos
Inibidores de Glicosídeo Hidrolases/química , Inibidores de Glicosídeo Hidrolases/farmacologia , Oligossacarídeos/química , Oligossacarídeos/farmacologia , alfa-Amilases Pancreáticas/antagonistas & inibidores , Streptomyces/química , Animais , Sequência de Carboidratos , Proliferação de Células/efeitos dos fármacos , Inibidores de Glicosídeo Hidrolases/isolamento & purificação , Oligossacarídeos/isolamento & purificação , Suínos
14.
Chemosphere ; 210: 257-266, 2018 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-30005347

RESUMO

A set of binary composites α-Fe2O3/Bi12O17Cl2 were established through an in-situ deposition route and these samples were systematically characterized by a collection of analytical techniques. Scanning electron microscopy, UV-vis diffuse reflectance spectroscopy, and X-ray photoelectron spectroscopy proved the coexistence of expected two components. High resolution transmission electron microscopy and selected-area electron diffraction indicated the formation of heterojunction domains with the intimate contact of both semiconductors. The degradation behavior of as-synthesized samples was evaluated under visible-light irradiation and the enhanced outcome was observed over dye methyl orange (MO) and colorless 2,4-dichlorophenol (2,4-DCP), mainly attributing to favorable optical and morphological merits, and a suitable well-aligned band structure in these binary composites with a suitable phase composition as well. In addition, these composites showed an obvious photo-Fenton feature that significantly improved the catalytic degradation efficiency over 2,4-DCP when the reagent H2O2 was introduced, indicating the destruction efficiency was controlled by a synergtic effect from both photocatalytic and photo-Fenton degradation routes. Based upon the detection of reactive radical species, a primary synergistic mechanism was eventually speculated.


Assuntos
Composição de Medicamentos , Compostos Férricos/química , Peróxido de Hidrogênio/química , Ferro/química , Fotólise , Catálise , Semicondutores
15.
Curr Eye Res ; 43(10): 1260-1266, 2018 10.
Artigo em Inglês | MEDLINE | ID: mdl-29874938

RESUMO

PURPOSE: To investigate real-time intraocular pressure (IOP) during small incision lenticule extraction (SMILE) in rabbit eyes for myopia correction. METHODS: During SMILE, real-time IOP was measured in the vitreous cavity of rabbit eyes with an optic fiber pressure sensor (OFPS). Two groups (n = 6 for each) underwent surgery, one group for a -2.00 diopter (D) refractive spherical correction and the other for a -6.00 D correction. RESULTS: During surgery, the IOP increased once the glass contact attached to the cornea (Pre-suction), and peaked 83.94 mmHg (SD ± 23.87 mmHg) for the -2.00 D group and 89.17 mmHg (SD ± 22.66 mmHg) for the -6.00 D group, both average values were less than 110 mmHg when suction was initiated to fix the glass contact onto the cornea (Suction on). It then fell to 74.81 mmHg (SD ± 20.64 mmHg) and 76.94 mmHg (SD ± 27.43 mmHg), respectively, and remained stable during lenticule creation (Cutting). After suction stopped (Suction off), IOP fell steeply. During lenticule separation/extraction, the change in IOP was 32.26 mmHg (SD ± 2.91 mmHg). Notably, the average duration of elevated IOP during the surgery was 166.05 s (no longer than 3 min). CONCLUSIONS: The IOP fluctuations in the vitreous cavity using an OFPS in a rabbit model during SMILE showed that real-time IOP significantly was increased during Pre-suction, Suction on, Cutting, Suction off, and lenticule separation/extraction compared to baseline IOP, although, peaked at Suction on. Neither the degree of myopic correction nor central corneal thickness significantly affected these changes in IOP.


Assuntos
Substância Própria/cirurgia , Cirurgia da Córnea a Laser/métodos , Pressão Intraocular/fisiologia , Transdutores de Pressão , Corpo Vítreo/fisiologia , Animais , Astigmatismo/cirurgia , Sistemas Computacionais , Feminino , Miopia/cirurgia , Estudos Prospectivos , Coelhos , Tonometria Ocular/instrumentação
16.
Biosens Bioelectron ; 101: 153-158, 2018 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-29065340

RESUMO

Theophylline is a popular drug for many respiratory diseases. However, certain toxic side effects may be developed and the narrow safety range raises the demand for sensitive methods to constantly monitor theophylline levels. This study presents an electrochemical approach towards theophylline detection based on the recognition by split RNA aptamers. Target induced construction of hand-in-hand RNA nanowire on the electrode surface could further absorb silver nanoparticles (Ag NPs) as electrochemical species. When theophylline is not present, RNA probes are stable and their conformations remain unchanged. In contrast, theophylline is able to trigger the hairpin opening of RNA probe and subsequent self-assembly of RNA nanowire, which could be captured by DNA tetrahedron on the electrode interface. After further decorating Ag NPs on the nanowire, silver stripping current is measured to reveal initial theophylline concentration. The developed sensing strategy shows excellent specificity and sensitivity with the limit of detection of 50nM. Its practical utility is demonstrated by quantitative determination of theophylline levels in complex biological samples.


Assuntos
Aptâmeros de Nucleotídeos/química , Técnicas Biossensoriais/métodos , Broncodilatadores/sangue , Nanofios/química , Teofilina/sangue , Adsorção , Broncodilatadores/análise , Técnicas Eletroquímicas/métodos , Humanos , Limite de Detecção , Nanopartículas Metálicas/química , Prata/química , Teofilina/análise
17.
J Mater Chem B ; 6(36): 5775-5780, 2018 Sep 28.
Artigo em Inglês | MEDLINE | ID: mdl-32254984

RESUMO

This study presents a facile synthesis method for the preparation of positively charged N,S co-doped carbon nanodots with excellent optical properties, and it develops a selective method for fluorescent detection of living cancer cells. The specific recognition is due to the application of an aptamer sequence, which shows high affinity and specificity to target cells. The aptamer is firstly labeled with BHQ and wraps around the carbon nanodots, then it finally quenches the fluorescence emission of the carbon nanodots. For the sensitive and selective analysis of target cells, the cells are simply mixed with the carbon nanodot-aptamer nanoconjugates, which are then centrifuged at a low speed. The recognition reaction between aptamer and target cells releases the quencher from the surface of the carbon nanodots and the centrifugation process enables the recovery of fluorescence intensity of the suspension, which reflects the level of initial cancer cells. The developed method is simple, highly selective and cost-effective, thus, it may be further exploited in clinical applications in the future.

18.
Asian Pac J Trop Med ; 10(9): 921-924, 2017 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-29080623

RESUMO

OBJECTIVE: To investigate the relationship between basal ganglia cerebral infarction and paroxysmal atrial fibrillation (PAF) caused by abnormal vagus nerve tension. METHODS: A total of 1483 cases of elder patients with cerebral infarction who received head CT or MRI examination during the period were enrolled, including 830 male and 613 female, with the average age as 78 years. These cases were divided into basal infarction ganglia group (n = 1045) and non-basal ganglia infarction group (n = 438) according to the anatomic site of cerebral infarction. The differences of the incidence of PAF, left atrial diameter and heart rate variability were compared between the two groups. RESULTS: In basal ganglia infarction group, the incidence rate of PAF was significantly higher than that of non-basal ganglia infarction group (P < 0.05). The incidence trend of cerebral infarction in basal ganglia was age-related, in the >79 years basal ganglia cerebral infarction group, the incidence of PAF was significantly higher than that of non-basal ganglia infarction group (P < 0.05). There was no significant difference in the left atrial diameter between the basal ganglia infarction group and non-basal ganglia infarction group. Basal ganglia cerebral infarction patients with high PAF had higher heart rate variability than non-basal ganglia infarction group. CONCLUSION: Elderly patients with basal ganglia infarction have high incidence of PAF. Sympathetic nerve damage in cerebral basal ganglia, increased vagal tension and cardiac vagal tension are the direct causes of PAF. The results indicates that the increased central vagal nerve tension mediated PAF probably is an indication of supplying sympathetic neurotransmitter or cardiac vagal denervation treatment.

19.
PLoS One ; 12(5): e0176603, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-28520739

RESUMO

Visual deprivation during the critical period induces long-lasting changes in cortical circuitry by adaptively modifying neuro-transmission and synaptic connectivity at synapses. Spike timing-dependent plasticity (STDP) is considered a strong candidate for experience-dependent changes. However, the visual deprivation forms that affect timing-dependent long-term potentiation(LTP) and long-term depression(LTD) remain unclear. Here, we demonstrated the temporal window changes of tLTP and tLTD, elicited by coincidental pre- and post-synaptic firing, following different modes of 6-day visual deprivation. Markedly broader temporal windows were found in robust tLTP and tLTD in the V1M of the deprived visual cortex in mice after 6-day MD and DE. The underlying mechanism for the changes seen with visual deprivation in juvenile mice using 6 days of dark exposure or monocular lid suture involves an increased fraction of NR2b-containing NMDAR and the consequent prolongation of NMDAR-mediated response duration. Moreover, a decrease in NR2A protein expression at the synapse is attributable to the reduction of the NR2A/2B ratio in the deprived cortex.


Assuntos
Potenciação de Longa Duração , Depressão Sináptica de Longo Prazo , Privação Sensorial , Córtex Visual/fisiologia , Animais , Fenômenos Eletrofisiológicos , Camundongos , Plasticidade Neuronal , Subunidades Proteicas , Receptores de N-Metil-D-Aspartato/genética , Receptores de N-Metil-D-Aspartato/metabolismo , Sinapses , Fatores de Tempo
20.
ACS Omega ; 2(6): 2469-2473, 2017 Jun 30.
Artigo em Inglês | MEDLINE | ID: mdl-30023666

RESUMO

Endotoxin is the major structural constituent of the outer membrane of Gram-negative bacteria, which is a great threat to human health. Herein, a sensitive electrochemical biosensor for the detection of endotoxin is established by recording the voltammetric responses of the peptide-modified electrode. The utilized peptide has a high affinity for the target endotoxin, which ensures the high selectivity of this method. After the capture of endotoxin on the electrode surface, a negatively charged layer is formed, and the electron-transfer process is significantly hindered because of the increased steric hindrance and the electrostatic repulsion. The declined electrochemical signal could be used to indicate the concentration of endotoxin. This method is simple but effective, which requires limited reagents. Another highlight of this method is its user-friendly operation. Moreover, its applicability in human blood plasma promises its great potential utility in the near future.

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