Qingyun Liu
Shandong University of Science and Technology
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Featured researches published by Qingyun Liu.
Analytical Chemistry | 2017
Jingjing Li; Qingyun Liu; Hongyan Xi; Xiangcong Wei; Zhengbo Chen
Herein, we present a novel gold nanoparticle (AuNP) enumeration-based colorimetric aptamer biosensor for ultrasensitive detection of nucleic acid. This AuNP enumeration-based colorimetric method takes advantages of the distinctive and strong localized surface plasmon resonance light scattering with the dark-field microscope. In our model system, first, cost-effective DNA1 instead of expensive 2-thioethyl ether acetic acid was capped on the surface of AuNPs to form a dense DNA1 layer. Then, two DNA strands (DNA2 and DNA3) in two different solutions were separately asymmetrically functionalized on the AuNPs capped dense DNA1 layer. The subsequent binding of the target DNA could trigger the formation of perfect complementary DNA with a Y shape and adjust the distance between nanoparticles to form AuNP dimers, accompanied by a color change from green to yellow as observed, and thereby modulated the performance of the sensor, which resulted in the ultrahigh sensitivity. With this design, a 43 aM limit of detection was obtained, which exhibited an increase of at least 5-9 orders of magnitude in sensitivity over other colorimetric sensors fabricated using conventional strategies.
Mikrochimica Acta | 2018
Yunfei Jiao; Qingyun Liu; Hong Qiang; Zhengbo Chen
AbstractA rapid, highly sensitive and selective colorimetric assay is presentedxa0for visually detecting L-histidine. It is based on L-histidine-triggered self-cleavage of DNA duplex-induced gold nanoparticle (AuNP) aggregation. The citrate-capped AuNPs easily aggregate in a high concentration of salt environment. However, in the presence of L-histidine aptamers (DNA1 and DNA2), the partial strands of DNA1 and DNA2 hybridize to form a DNA duplex with a swing structure. The swing-like DNA duplexes are adsorbed on the surface of AuNPs to improve the stability of AuNPs, and thexa0AuNPs also are better dispersed in high-salt media. When L-histidine is added to the solutions, it catalyzes the self-cleavage of DNA1 to form many single-stranded DNA (ssDNA) fragments. These ssDNA segments arexa0adsorbed on thexa0AuNPs and weaken the stability of AuNPs. Hence, the AuNPs aggregate in high-salt environment, and thisxa0results in a red-to-blue color change. Under the optimized conditions, L-histidine can be determinedxa0with a limit of detection of 3.6xa0nM. In addition, the sensor was successfully applied to the determination ofxa0L-histidine in spiked serum samples.n Graphical abstractSchematic of a rapid and homogeneous colorimetric L-histidine assay. It combines L-histidine-triggered self-cleavage of the swing-like DNA duplexes and self-cleavage of DNA-induced AuNP aggregation.
Mikrochimica Acta | 2018
Yudong Tian; Qingyun Liu; Yunfei Jiao; Ru Jia; Zhengbo Chen
A colorimetric method is described for sensitive and low-cost detection of Cd(II). It is based on the use of triangular silver nanoplates (tri-AgNPs) modified with 1-amino-2-naphthol-4-sulfonate (ANS) acting as a colorimetric probe. ANS is first linked to the tri-AgNPs via electrostatic interaction of the sulfo groups. In the absence of analyte, ANS on the surface of tri-AgNPs protects them from aggregation. In the presence of Cd(II), the tri-AgNPs aggregate due to the interaction between ANS and Cd(II). This results in a distinct color change from blue (absorption peak at 710xa0nm) to green (peak at 770xa0nm). UV-vis spectrometry and image analyses demonstrate that this method exhibits selective and sensitive colorimetric response to Cd(II). The color change can be easily detected with bare eyes. Response is linear in the 30 to 70xa0μM concentration range, and the detection limit is 30xa0nM.Graphical abstractA colorimetric method for sensitive, and low-cost detection of Cd(II) based on the use of tri-AgNPs modified with ANS acting as a colorimetric probe was presented.
Analytical Chemistry | 2018
Lihua Lu; Huijuan Su; Qingyun Liu; Feng Li
To improve the G-quadruplex specificity of Ir(III) complexes, a novel dinuclear Ir(III) complex (Din Ir(III)-1) was designed and synthesized through connecting two mononuclear Ir(III) complexes via a diphenyl bridge. Din Ir(III)-1 presents 3.4-4.1-fold enhancements for G-quadruplex relative to ssDNA and 4.3-5.3-fold enhancements relative to dsDNA in luminescence intensity, respectively, demonstrating an excellent G-quadruplex selectivity. Ascribed to its superior specificity to G-quadruplex, Din Ir(III)-1 was employed to construct a highly sensitive luminescent pesticides detection platform. The detection is based on acetylcholinesterase (AChE)-catalyzed hydrolysis product-induced DNA conformational transformation and subsequent terminal deoxynucleotidyl transferase (TdT) directed G-quadruplex formation. The assay exhibited a linear response between the emission intensity of Din Ir(III)-1 and the pesticide concentration in the range of 0.5-25 μg/L ( R2 = 0.994), and the limit of detection for the pesticide was as low as 0.37 μg/L when using aldicarb as the model pesticide. Moreover, this strategy demonstrates good applicability for the pesticide detection in real samples. It is also versatile for the detection of other organophosphate or carbamate pesticides, which have the inhibition ability toward AChE. Therefore, the proposed approach is scalable for practical application in food safety and environmental monitoring fields and will provide promising solutions for the assay of pesticide residues.
Analytical Chemistry | 2018
Jingjing Li; Hongyan Xi; Caiyun Kong; Qingyun Liu; Zhengbo Chen
Robust but ultrasensitive aptasensors with an ability to detect lower concentrations of heavy metal ions enable the detection of serious environmental and health issues. We herein develop a label-free aptasensor for ultrasensitive detection of the silver ion (Ag+) utilizing gold nanoparticle (AuNP) intensity measurement methodology by dark-field microscopy, which is based on target Ag+ and exonuclease III (Exo III)-dependent DNA cleavage recycling amplification. In the presence of target Ag+, thymine (T) bases at two termini of hairpin DNA bind with Ag+ through C-Ag+-C coordination to form a DNA duplex, Exo III can recognize the blunt 3 end of the DNA duplex and digest it from the 3 end to the 5 direction. The released target Ag+ then binds with another hairpin DNA via C-Ag+-C pairs. After many cycles of the digestion of the DNA duplex by Exo III, numerous remaining single-stranded DNA (ssDNA) are generated. These ssDNA are absorbed on the surface of AuNPs, enhancing the repulsion force between AuNPs, which further promotes the dispersion of AuNPs, leading to a significantly decreased intensity of yellow and red dots (aggregated AuNPs) under dark-field microscopy observation, in contrast to that of the blank solution (without target Ag+). On this basis, the detection limits of 41 and 39 fM were achieved for Ag+ in Tris-HCl buffer and river water, respectively.
Analytical Chemistry | 2018
Weiwei He; Long Luo; Qingyun Liu; Zhengbo Chen
In the present work, we report a novel colorimetric sensor array for rapid identification of heavy metal ions. The sensing mechanism is based on the competition between thiols and urease for binding with the metal ions. Due to the different metal ion-binding abilities between the thiols and urea, different percentages of urease are free of metal ions and become catalytically active in the presence of varied metal ions. The metal ion-free urease catalyzes the decomposition of urea releasing ammonia and changing the pH of the analyte solution. Bromothymol blue, the pH indicator, changes its color in response to the metal-caused pH change. Three different thiols (l-glutathione reduced, l-cysteine, and 2-mercaptoethanol) were used in our sensor array, leading to a unique colormetric repsonse pattern for each metal. Linear discriminant analysis (LDA) was employed to analyze the patterns and generate a clustering map for identifying 11 species of metal ions (Ni2+, Mn2+, Zn2+, Ag+, Cd2+, Fe3+, Hg2+, Cu2+, Sn4+, Co2+, and Pb2+) at 10 nM level in real samples. The method realizes the simple, fast (within 30 s), sensitive, and visual discrimination of metal ions, showing the potential applications in environmental monitoring.
Analytica Chimica Acta | 2018
Jingjing Li; Yunfei Jiao; Qingyun Liu; Zhengbo Chen
We present a simple and efficient colorimetric assay strategy for ultrasensitive visual detection of human α-thrombin, which is essentially based on the formation of the DNA1-thrombin-DNA2 sandwich complex-bridged gold nanoparticle (Au NP) oligomers. Unlike the traditional colorimetric sensing strategies which induced the nanoparticle aggregates with uncontrolled aggregate size. In this work, the DNA1with rich G bases was firstly conjugated on the surfaces of Au NPs fixed on the hexadecyl trimethylammonium bromide (CTAB)-coated glass slide, and thrombin was captured by the DNA1. Then, the other DNA2 with rich G bases interacted with the former DNA1-thrombin complex and formed a DNA1-thrombin-DNA2 sandwich complex. The subsequently added Au NPs can be bound to the Au NP-DNA1-thrombin-DNA2 via Au-S bond to trigger the formation of Au NP oligomers, an apparent color change of the single Au NPs from green to yellow and red was observed under dark field microscopy. By measuring the intensity change of the yellow and red Au NPs, the concentration of target thrombin could be accurately quantified. As a proof of concept experiment, the formation of Au NP oligomers resulted in significantly improved sensitivity (10u202ffM of limit of detection and 20u202ffM of limit of quantity) and wider linear dynamic range of thrombin detection (20u202ffM-20u202fnM), the relative standard deviation (RSD) was less than 5.73% (nu202f=u202f5). In addition, in order to validate the potential application in clinical diagnosis, the content of thrombin in a human serum samples was also quantified.
Analyst | 2018
Jingjing Li; Caiyun Kong; Qingyun Liu; Zhengbo Chen
Analyst | 2018
Hongyan Xi; Xin Li; Qingyun Liu; Zhengbo Chen
ACS Sustainable Chemistry & Engineering | 2018
Hong Qiang; Xiangcong Wei; Qingyun Liu; Zhengbo Chen