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Quantification of DNA by a Thermal-Durable Biosensor Modified with Conductive Poly(3,4-ethylenedioxythiophene)
摘要： The general clinical procedure for viral DNA detection or gene mutation diagnosis following polymerase chain reaction (PCR) often involves gel electrophoresis and DNA sequencing, which is usually time-consuming. In this study, we have proposed a facile strategy to construct a DNA biosensor, in which the platinum electrode was modified with a dual-film of electrochemically synthesized poly(3,4-ethylenedioxythiophene) (PEDOT) resulting in immobilized gold nanoparticles, with the gold nanoparticles easily immobilized in a uniform distribution. The DNA probe labeled with a SH group was then assembled to the fabricated electrode and employed to capture the target DNA based on the complementary sequence. The hybridization efficiency was evaluated with differential pulse voltammetry (DPV) in the presence of daunorubicin hydrochloride. Our results demonstrated that the peak current in DPV exhibited a linear correlation the concentration of target DNA that was complementary to the probe DNA. Moreover, the electrode could be reused by heating denaturation and re-hybridization, which only brought slight signal decay. In addition, the addition of the oxidized form of nicotinamide adenine dinucleotide (NAD+) could dramatically enhance the sensitivity by more than 5.45-fold, and the limit-of-detection reached about 100 pM.
关键词： poly(3,4-ethylenedioxythiophene),gold nanoparticle,electron transfer mediate,DNA biosensor
更新于2025-09-23 15:21:21
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A versatile fluorometric in-situ hybridization method for the quantitation of hairpin conformations in DNA self-assembled monolayers
摘要： As the performance of hairpin DNA (hpDNA)-based biosensors is highly dependent on the yield of stem-loop (hairpin) conformations, we report herein a versatile fluorometric in-situ hybridization protocol for examining hpDNA self-assembled monolayers (SAMs) on popularly used biochip substrates. Specifically, the ratio of fluorescence (FL) intensities of hpDNA SAMs (in an array format) before and after hybridization was adapted as the key parameter for performing such a determination. Upon confirming the existence of mixed and tunable DNA conformations in binary deposition solutions and the efficient hybridization of the hairpin strands with target DNA via gel electrophoresis assays, we have tested the fluorometric protocol for determining the coverages of hpDNA in hpDNA/ssDNA SAMs prepared on gold; its accuracy was validated by Exonuclease I (Exo I)-assisted electrochemical quantitation. To further confirm its versatility, this FL protocol was adapted for quantifying hairpin conformations formed on glass and polycarbonate (PC) substrates. The molar ratios of surface-tethered hairpin conformations on the three different substrates were all found to be proportional to but less than that in the binary deposition solutions, and dependent on the substrate morphology. The findings reported herein are beneficial to the construction of highly efficient DNA hairpin-based sensing surfaces, which essentially facilitates the creation of hpDNA-based biosensors with optimal detection performance.
关键词： In-situ hybridization,conformation evaluation,DNA biosensor/biochip,fluorescence microarray,Hairpin DNA
更新于2025-09-23 15:19:57
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The Conductivity of the Monolayer of DNA a?? Quantum Dot Complexes in the Presence of Intercalating Charged Ligands
摘要： The resistance of a monolayer of complexes of the double-stranded DNA with quantum dots were computed. It was shown that with the non-competitive DNA hybridization and in the presence of monovalent positively charged ligands in the solution, a decrease in resistance occurs as compared to that for uncharged ligands. It is shown that the charged ligands enhance the sensitivity of the DNA chips as compared to the uncharged ones.
关键词： DNA,biosensor,intercalator,conductivity
更新于2025-09-23 15:19:57
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A novel three-dimensional microTAS chip for ultra-selective single base mismatched Cryptosporidium DNA biosensor
摘要： The development of new rapid and reliable detection technology of Cryptosporidium, a deadly waterborne pathogen, using a three-dimensional micro total analysis systems (3D μTAS) is the main goal of this work. An approach to enhance DNA detection on a patterned configurable 3D μTAS electrochemical DNA biosensor to human genotype of Cryptosporidium was successfully developed in present study. A novel 3D μTAS, comprising three layers, was fabricated to achieve better result comparing the commercial SPE. The first layer was consisted a circular gold coated area (gold dot) in the center of a PI sheet and the third layer was consisted of a common homemade screen printed electrode (SPE). The second layer was included PDMS channels and reservoir for sample delivery. The biosensor was fabricated on the gold dot of the first layer and electrochemical signal was recorded using the differential pulse voltammetry (DPV) and impedance methods on the third layer and the results were compared with biosensor fabricated on commercial SPE. The calibration curve of 3D μTAS DNA biosensor shows a detection limit of 1.8 ng/mL and a sensitivity of 12.844 μA/(μg mL-1) in a linear range of 2.5 ng/mL to 0.1 μg/mL, which are 10 times higher detection limit and 23 higher sensitivity of commercial SPE in a similar linear range. The specificity of prepared DNA sensor was conducted by using non-complementary, single, three and five mismatches strands and the potential of the biosensor in discriminating single mismatch detection was experimentally appraised.
关键词： Cryptosporidium,electrochemical DNA biosensor,E. Coli DNA,3D micro total analysis systems (3D μTAS)
更新于2025-09-09 09:28:46
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Surface regeneration and reusability of label-free DNA biosensors based on weak polyelectrolyte-modified capacitive field-effect structures
摘要： The reusability of capacitive field-effect electrolyte-insulator-semiconductor (EIS) sensors modified with a cationic weak polyelectrolyte (poly(allylamine hydrochloride) (PAH)) for the label-free electrical detection of single-stranded DNA (ssDNA), in-solution- and on-chip-hybridized double-stranded DNA (dsDNA) has been studied. It has been demonstrated that via simply regeneration of the gate surface of the EIS sensor by means of an electrostatic adsorption of a new PAH layer, the same biosensor can be reused for at least five DNA-detection measurements. Because of the reversal of the charge sign of the outermost layer after each surface modification with the cationic PAH or negatively charged DNA molecules, the EIS-biosensor signal exhibits a zigzag-like behavior. The amplitude of the signal changes has a tendency to decrease with increasing number of macromolecular layers. The direction of the EIS-signal shifts can serve as an indicator for a successful DNA-immobilization or -hybridization process. In addition, we observed that the EIS-signal changes induced by each surface-modification step (PAH adsorption, immobilization of ssDNA or dsDNA molecules and on-chip hybridization of complementary target cDNA) is decreased with increasing the ionic strength of the measurement solution, due to the more efficient macromolecular charge-screening by counter ions. The results of field-effect experiments were supported by fluorescence-intensity measurements of the PAH- or DNA-modified EIS surface using various fluorescence dyes.
关键词： charge screening,label-free,field-effect sensor,DNA biosensor,reusability,weak polyelectrolyte
更新于2025-09-09 09:28:46
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Characterization of Polylactide-Stabilized Gold Nanoparticles and Its Application in the Fabrication of Electrochemical DNA Biosensors
摘要： In this work, two different approaches to gold nanoparticles (AuNPs) have been explored for the modification of screen-printed electrode based on AuNPs and AuNPs stabilized with polylactic acid (PLA). The modified substrate has been characterized using UV-Vis spectroscopy, X-ray diffraction (XRD), transmission electron microscopy (TEM), field emission scanning electron microscopy (FESEM) and cyclic voltammetry. Both synthesized AuNPs were studied in terms of stability, sensitivity and reproducibility to enhance the sensing capability of modified electrodes. The PLA-stabilized AuNPs form strong structured nanoparticles and stabilize in aqueous solution. A larger active surface area (0.41 cm2) and lower charge transfer resistance (Rct) value were reported in the modification of sensing material with PLA-stabilized AuNPs, which resulted in enhancement of sensitivity. Therefore, AuNPs in PLA can be used as a potential alternative modifier for sensing chemicals and biomolecules in electrochemical sensors.
关键词： gold nanoparticles,polylactic acid,screen-printed carbon electrode,electrochemical DNA biosensor
更新于2025-09-09 09:28:46
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Integrating an ex-vivo skin biointerface with electrochemical DNA biosensor for direct measurement of the protective effect of UV blocking agents
摘要： Skin cancer is the most frequent kind of cancer in white people in many parts of the world. UV-induced DNA damage and genetic mutation can subsequently lead to skin cancer. Therefore development of new biosensing strategies for detection of UV-induced DNA damage is of great importance. Here we demonstrate a novel combination of an ex-vivo skin biointerface and an electrochemical DNA sensor for the direct detection of UV induced DNA damage and investigation the protective effect of various UV blockers (Zinc-oxide (ZnO), titanium-dioxide (TiO2) nanoparticles (NPs) and sunscreens) against DNA damage. A diazonium modified screen-printed carbon electrode immobilized with a DNA sequence related to the p53 tumour suppressor gene, the most commonly affected gene in human UV-induced skin cancer, was applied as an electrochemical DNA sensor. Electrochemical impedance spectroscopy (EIS) was employed for the detection of DNA damage induced by UV-A radiation by following the changes in charge transfer resistance (Rct). The protective effects of UV blockers applied onto a pig skin surface (a suitable model representing human skin) were successfully detected by the DNA sensor. We observed that the naked skin has little UV protection showing an 18.2% decreases in ?R/R values compared to the control, while applying both NPs and NP-formulated sunscreens could significantly reduce DNA damage, resulting in a decrease in ?R/R values of 67.1% (ZnO NPs), 77.2% (TiO2 NPs), 77.1% (sunscreen 1) and 92.4% (sunscreen 2), respectively. Moreover, doping moisturising cream with NPs could provide a similar DNA protective effect. This new method is a biologically relevant alternative to animal testing and offers advantages such as fast, easy and inexpensive processing, in addition to its miniaturised dimension, and could be used for a range of applications in other sources of DNA damage and the protective effect of different UV blocking agents and other topical formulations.
关键词： sunscreens,electrochemical DNA biosensor,skin biointerface,DNA damage,nanoparticles
更新于2025-09-04 15:30:14