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Thin-core fiber-optic biosensor for DNA hybridization detection
摘要： A real-time label-free DNA biosensor based on thin-core fiber (TCF) interferometer is demonstrated experimentally. The proposed biosensor is constructed by splicing a TCF between two segments of single mode fibers (SMFs) and integrated into a microfluidic channel. By modifying the TCF surface with monolayer poly-l-lysine (PLL) and single-stranded deoxyribonucleic acid (ssDNA) probes, the target DNA molecules can be captured in the microfluidic channel. The transmission spectra of the biosensor are measured and theoretically analyzed under different biosensing reaction processes. The results show that the wavelength has a blue-shift with the process of the DNA hybridization. Due to the advantages of low cost, simple operation as well as good detection effect on DNA molecules hybridization, the proposed biosensor has great application prospects in the fields of gene sequencing, medical diagnosis, cancer detection and environmental engineering.
关键词： thin-core fiber,biosensor,microfluidic channel,modal interference,DNA hybridization
更新于2025-11-28 14:23:57
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Ultrathin Ti3C2 Nanosheets based “off-on” Fluorescent nanoprobe for Rapid and Sensitive Detection of HPV Infection
摘要： MXenes as a new class of 2D materials have recently been widely applied in energy storage, electrocatalysis, sensors, adsorption, water purification, and so on, due to their tunable versatile properties. Herein, we demonstrate a simple, rapid and highly-sensitive sensing platform based on ultrathin two-dimensional MXene Ti3C2 nanosheets (Ti3C2 NSs) for selective analysis of Human papillomavirus (HPV), a major human pathogens and causative agents of cervical cancer. Ultrathin Ti3C2 NSs, obtained by exfoliating their layered HF-etched powder, exhibit high fluorescence quenching ability to dye-labeled single-stranded DNA (ssDNA) and different affinities for ssDNA and double-stranded DNA (dsDNA). Under the fluorescence quenching effect of Ti3C2 NSs, ssDNA probe (P) shows the minimal fluorescent emission. After the formation of duplex structure with its complementary target, ssDNA (T), the fluorescence intensity enhances evidently. Exonuclease III (Exo III) was used to improve the sensitivity by promoting more fluorescence enhancement. This magnified fluorescent sensor for HPV-18 detection shows a low detection limit of 100 pM and a high specificity. Furthermore, the developed DNA sensor can be employed to determine PCR amplified HPV-18 from cervical scrapes samples. It highlights ultrathin Ti3C2 NSs as a potential candidate for construction of fluorescence DNA biosensors with excellent performances.
关键词： DNA hybridization,Ti3C2 nanosheets,HPV,Fluorescent detection
更新于2025-11-19 16:46:39
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A fluorescence method for homogeneous detection of influenza A (H1N1) DNA sequence based on Guanine(G)‐quadruplex‐ N‐methylmesoporphyrin IX (NMM) complex and Assistance‐DNA (A‐DNA) inhibition
摘要： In this work, we report a fluorescence method for homogeneous detection of influenza A (H1N1) DNA sequence based on G-quadruplex-NMM complex and Assistance DNA (A-DNA) inhibition. The quadruplex-based functional DNA (QBF-DNA), composed of complementary probe to the target H1N1 DNA sequence and G-rich fragment, was designed as the signal DNA. The A-DNA consisted of two parts, one part was complementary to target H1N1 DNA and the other part was complementary to the signal DNA. In the absence of target H1N1 DNA, the G-rich fragment of QBF-DNA can form G-quadruplex-NMM complex, which outputted a fluorescent signal. With the presence of target H1N1 DNA, QBF-DNA and A-DNA can simultaneously hybridize with target H1N1 DNA to form double-helix structure. In this case, the A-DNA partially hybridized with the QBF-DNA, which inhibited the formation of G-quadruplex-NMM complex, leading to the decrease of fluorescent signal. Under the optimum conditions, the fluorescence intensity was inversely proportional to the concentration of target H1N1 DNA over the range from 25pmol/L to 700pmol/L with a detection limit of 8pmol/L. In addition, the method is target specific and practicability, and would become a new diagnostic assay for influenza A (H1N1) DNA sequence and other infectious diseases.
关键词： G-quadruplex,H1N1 virus,Fluorescence method,DNA hybridization
更新于2025-09-19 17:15:36
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Size effect of metal nanodome arrays on performance of plasmonic biosensor
摘要： Size effect of metal nanodome arrays on performance characteristics of a plasmonic biosensor is investigated using reflection spectroscopy. Ag and Au nanodome arrays are created by a bottom-up nanofabrication process by which the dome diameter and metal thickness can be controlled. Reflectivity measurements of metal nanodome arrays showed that the wavelengths and width of resonance dip were changed by the dome diameter and metal thickness, respectively. Bulk refractive index (RI) sensing and detection of DNA hybridization were performed to characterize the sensing performance of metal nanodome arrays. Bulk RI sensitivity were significantly improved as the dome diameter enlarged from 100 to 500 nm. In contrast, metal nanodome arrays with smaller diameter exhibited higher sensor signals against the immobilization of DNA modified gold nanoparticles used for signal amplification indicating strong plasmonic coupling effects. With respect to the dome diameter, the effect of metal thickness was moderate for the presented sensing scheme.
关键词： plasmonic biosensor,metal nanodome arrays,bulk refractive index sensitivity,DNA hybridization,reflection spectroscopy
更新于2025-09-11 14:15:04
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Design and numerical analysis of a graphene-coated fiber-optic SPR biosensor using tungsten disulfide
摘要： This article provides a simple hybrid design and rigorous numerical analysis of a fiber optic–based surface plasmon resonance (SPR) biosensor for DNA hybridization. The sensor core and both sides of the cladding are constructed with optical fiber, whereas the middle portion of the cladding is filled with the proposed hybrid of silver, tungsten disulfide (WS2), graphene, and a sensing medium. To the best of our knowledge, this is the first demonstration of such a highly sensitive SPR biosensor using WS2 for sensing DNA hybridization. The sensitivity, detection accuracy, and figure of merit are considered as the performance parameters and are analyzed in detail. The analyses reveal an impressive enhancement of the overall performance of the proposed sensor. Insertion of a WS2 layer between silver and graphene provides a sensor with sensitivity higher than that of other sensors reported to date. Additionally, concurrent improvement of all performance parameters is shown by this hybrid sensor, which is not the case for sensors based only on graphene. An increased number of graphene-only layers increases the sensitivity and decreases the detection accuracy and figure of merit. Numerical analysis shows that the variation of the SPR angle for mismatched DNA strands is quite negligible, whereas that for complementary DNA strands is considerable, which is essential for proper detection of DNA hybridization. Therefore, the proposed biosensor opens a new window toward detection of biomolecular interactions.
关键词： DNA hybridization,transmittance,surface plasmon resonance angle,Biosensor,sensitivity,tungsten disulfide
更新于2025-09-09 09:28:46
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Ultra-Sensitive and Label-Free Probing of Binding Affinity Using Recognition Imaging
摘要： Reliable quantification of binding affinity is important in biotechnology and pharmacology and increasingly coupled with a demand for ultrasensitivity, nanoscale resolution, and minute sample amounts. Standard techniques are not able to meet these criteria. This study provides a new platform based on atomic force microscopy (AFM)-derived recognition imaging to determine affinity by visualizing single molecular bindings on nanosize dendrons. Using DNA hybridization as a demonstrator, an AFM sensor adorned with a cognate binding strand senses and localizes target DNAs at nanometer resolution. To overcome the limitations of speed and resolution, the AFM cantilever is sinusoidally oscillated close to resonance conditions at small amplitudes. The equilibrium dissociation constant of capturing DNA duplexes was obtained, yielding 2.4 × 10?10 M. Our label-free single-molecular biochemical analysis approach evidences the utility of recognition imaging and analysis in quantifying biomolecular interactions of just a few hundred molecules.
关键词： scanning probe microscopy,DNA hybridization,Affinity,molecular recognition,single-molecule
更新于2025-09-04 15:30:14