- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Sandwiching analytes with structurally diverse plasmonic nanoparticles on paper substrates for surface enhanced Raman spectroscopy
摘要： This report describes the systematic combination of structurally diverse plasmonic metal nanoparticles (AgNPs, AuNPs, Ag core–Au shell NPs, and anisotropic AuNPs) on flexible paper-based materials to induce signal-enhancing environments for surface enhanced Raman spectroscopy (SERS) applications. The anisotropic AuNP-modified paper exhibits the highest SERS response due to the surface area and the nature of the broad surface plasmon resonance (SPR) neighboring the Raman excitation wavelength. The subsequent addition of a second layer with these four NPs (e.g., sandwich arrangement) leads to the notable increase of the SERS signals by inducing a high probability of electromagnetic field environments associated with the interparticle SPR coupling and hot spots. After examining sixteen total combinations, the highest SERS response is obtained from the second layer with AgNPs on the anisotropic AuNP paper substrate, which allows for a higher calibration sensitivity and wider dynamic range than those of typical AuNP–AuNP arrangement. The variation of the SERS signals is also found to be below 20% based on multiple measurements (both intra-sample and inter-sample). Furthermore, the degree of SERS signal reductions for the sandwiched analytes is notably slow, indicating their increased long-term stability. The optimized combination is then employed in the detection of let-7f microRNA to demonstrate their practicability as SERS substrates. Precisely introducing interparticle coupling and hot spots with readily available plasmonic NPs still allows for the design of inexpensive and practical signal enhancing substrates that are capable of increasing the calibration sensitivity, extending the dynamic range, and lowering the detection limit of various organic and biological molecules.
关键词： SERS,surface enhanced Raman spectroscopy,interparticle coupling,microRNA detection,plasmonic nanoparticles,paper substrates,signal enhancement,hot spots
更新于2025-09-16 10:30:52
-
Using optical tweezers to construct an upconversion luminescent resonance energy transfer analytical platform
摘要： We report a new upconversion nanoparticles (UCNPs) based luminescent resonance energy transfer (LRET) analytical platform by making use of optical tweezers technology. The LRET model is designed by simultaneously conjugating Yb3+ and Er3+ co-doped UCNPs (as the donors) and tetramethyl rhodamine (TAMRA) molecules (as the acceptors) on microspheres to fabricate complex microspheres. Upon a single complex microsphere entering the three-dimensional potential well formed with a tightly focused 980 nm Guassian-shaped laser beam, it is optically trapped and concurrently the upconversion emission is excited, whereby the donor signals are transferred to the acceptors. As a proof-of-concept investigation, microRNA-21 sequences are selected as the targets, by which the distance between the two perfectly matched luminophors is controlled to several nanometers via nucleic acid hybridization. Without the involvement of luminescence amplification strategies, the proposed single microsphere based LRET method shows highly competitive sensitivity with a limit of detection down to 114 fM and satisfactory specificity towards microRNAs detection. Moreover, its practical working ability is demonstrated by credibly quantifying the absolute contents of miRNA-21 sequences in three cancer cell lines and even tracing the targets in as few as 100 cancer cells. Thus, this favorable analytical methodology provides an alternative for bioassays and holds certain potential in biomedical applications.
关键词： microRNA detection,Upconversion nanoparticle (UCNPs),Luminescent resonance energy transfer (LRET),Optical tweezers
更新于2025-09-10 09:29:36
-
A Novel Fluorescence Switch for MicroRNA Imaging in Living Cells based on DNAzyme Amplification Strategy.
摘要： MicroRNAs (miRNAs) play important roles in the regulation of target gene expression and cell development. Therefore, developing of accurate and visual detection methods for miRNAs is important for early diagnosis of cancer. In this study, we established a visual detection method for miRNA 155 based on DNAzyme amplification strategy in living cells. MnO2 nanosheets were employed to deliver Locked DNAzyme and Substrate DNA into cells. AuNPs-Probe were taken up by cells autonomously. Then, MnO2 nanosheets were reduced to Mn2+ by glutathione (GSH) in cells and DNA modules were released. MiRNA 155 took away Locker DNA by strand displacement reaction to activate the DNAzyme. Then the DNAzyme cleaved substrate DNA and released single-stranded DNA named Key DNA. Key DNA opened the hairpin DNA that modified on gold nanoparticles (AuNPs) and turn on the fluorescence of cy5. One target miRNA led to plenty of released Key DNA when lots of substrate DNA were added. Thus, the visual detection of miRNA 155 in living cells would be initiated. Under confocal laser microscopy, the fluorescence was obviously observed in tumor cells but not in normal cells. The method has a linear range from 0.1 nM to 10 nM and a low detection limit of 44 pM in vitro detection.
关键词： DNA walker,microRNA,AuNPs,Fluorescence imaging,MnO2,DNAzyme,Signal amplification
更新于2025-09-09 09:28:46
-
Logic Sensing of MicroRNA in Living Cells Using DNA-Programmed Nanoparticle Network with High Signal Gain
摘要： Molecular circuits capable of implementing Boolean logic in cellular environments have emerged as an important tool for in situ sensing, elucidating, and modulating cell functions. The performance of existing molecular computation devices in living cells is limited because of the low level of biomolecular inputs and moderate signal gain. Herein, we devised a new class of DNA-programmed nanoparticle network with integrated molecular computation and signal amplification functions for logic sensing of dual microRNA (miRNA) molecules in living cells. The nanoparticle network, which is composed of DNA-bridged gold nanoparticles and quantum dots (QDs), could simultaneously interface with two miRNA molecules, amplify the molecular inputs, perform a calculation through AND logic gate, and generate QD photoluminescence (PL) as an output signal. Significant improvement in imaging sensitivity is achieved by integrating the signal amplifier into the molecular computation device. It allows discrimination of specific cancer cell type via intelligent sensing of miRNA patterns in living cells.
关键词： assembly,microRNA,DNA,cancer imaging,gold nanoparticle,logic gate,quantum dot
更新于2025-09-09 09:28:46
-
A Versatile Dynamic Light Scattering Strategy for the Sensitive Detection of Plant MicroRNAs Based‐on Click Chemistry‐Amplified Aggregation of Gold Nanoparticles
摘要： Plant microRNAs (miRNAs) are naturally 2′-O-methylated at the 3′-terminal, so they cannot be efficiently detected by traditional target-triggered polymerization reactions. Herein, a simple but robust enzyme-free sensing strategy is developed for plant miRNA analysis by using dynamic light scattering (DLS) technique to monitor the click chemical ligation-amplified crosslinking of gold nanoparticles (AuNPs). Combining the enzyme-free cycling chemical ligation-mediated signal amplification, and the intrinsic outstanding ability of DLS for discriminating the extremely low level of particle aggregation in a large pool of monodisperse AuNPs, high sensitivity is achieved and as low as 78.6 fM plant miRNA can be easily detected.
关键词： crosslinking,click chemistry,plant microRNA,dynamic light scattering (DLS),gold nanoparticles
更新于2025-09-09 09:28:46
-
Photocarcinogenesis & Photoprotection || UVR-Induced Epigenetic Regulation and Photocarcinogenesis
摘要： The human skin remains under constant exposure of solar radiation and is vulnerable to epigenetic modifications that later may develop skin cancer. The effects of chronic UVR exposure to skin can alter epigenetic information in epidermal cells, leading to epigenetic mosaicism. These epigenetic changes include DNA methylation, chromatin modifications, and posttranscriptional modifications of noncoding RNAs. UVR-induced epigenetic changes are not irreversible. Certain phytochemicals can potentially inhibit cancer signaling pathways which are usually deregulated by epigenetic mechanisms. Indeed, recent therapeutic strategies are directing toward phytochemical-based reversal of epigenetic modifications to combat UVR-induced skin cancers. This chapter provides detailed insights of different epigenetic alterations, their role in photocarcinogenesis, and phytochemical-based reversal of epigenetic changes occurring in UVR-irradiated skin.
关键词： Phytochemicals,Ultraviolet,MicroRNA,DNA methylation,Histone
更新于2025-09-04 15:30:14
-
An Electrogenerated Chemiluminescence Biosensor using a tripod probe for the Highly Sensitive Detection of MicroRNA
摘要： A novel probe for highly sensitive detection of microRNA, that enhanced the helix accessibility and yielded good assembling without backfilling, was developed using a tripod structure fabricated by triplex DNA. A layer of triplex DNA assembled on electrodeposited reduced graphene oxide was used as the capture probe and a subsequent hybridization chain reaction that promoted the efficient intercalation of the electrogenerated chemiluminescence(ECL) emitter [Ru(bpy)2(dppz)]2+ (bpy = 2,2′-bipyridine, dppz = dipyrido[3,2-a: 2′,3′-c]phenazine) was used an analytical signal amplifier. The fabricated biosensor was examined with an anodic ECL mode using tri-n-propyl amine as the coreactant. The construction of the biosensor was systematically characterized with various techniques including atomic force microscopy, gel electrophoresis, cyclic voltammetry, and electrochemical impedance spectroscopy, and its performance was optimized under a variety of experimental conditions especially the concentration of each reagent as well as its incubation time. Under the optimal experimental conditions, the reported biosensor showed a very low limit of detection of 0.10 fM (S/N = 3) and a wide linear dynamic range covering from 0.50 fM to 100 pM towards microRNA-155, with excellent specificity, stability, and reproducibility. Finally, the biosensor was successfully applied to detect the amount of microRNA-155 extracted from the colon cancer cell line DLD1, demonstrating its potential applications in sensitive detection of biological samples in early diagnosis of diseases.
关键词： Triplex DNA,HCR,ECL sensor,MicroRNA
更新于2025-09-04 15:30:14