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Gold nanoparticle-based plasmonic probe for selective recognition of adenosine
摘要： Adenosine, as an endogenous molecule in organisms, plays an essential role in biological processes. Here, a plasmonic probe, creatinine-Ag+/gold nanoparticle (AuNPs), is assembled for adenosine detection based on synergistic coordination on AuNPs. The A650 nm/520 nm values of AuNPs system change linearly with adenosine concentration over a range of 1.0–5.0 μM and the detection limits reached 45 nM. The adenosine detection is realized within 4 min. Furthermore, the quantitative detection of adenosine is realized by eyedropper (a function in Microsoft’s PowerPoint) for analyzing RGB value changes of colorimetric assay. Therefore, this sensor can provide accurate and rapid assay of adenosine in patients’ serum sample without complicated instrumentations.
关键词： colorimetric assay,adenosine detection,eyedropper function,gold nanoparticle,plasmonic probe
更新于2025-11-19 16:56:42
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Comparison of turn-on and ratiometric fluorescent G-quadruplex aptasensor approaches for the detection of ATP
摘要： Two fluorescent aptasensor methods were developed for the detection of ATP in biochemical systems. The first method consisted of a label-free fluorescent Bturn-on^ approach using a guanine-rich ATP aptamer sequence and the DNA-binding agent berberine complex. In the presence of ATP, the ATP preferentially binds with its aptamer and conformationally changes into a G-quadruplex structure. The association of berberine with the G-quadruplex results in the enhancement of the fluorescence signal of the former. The detection limit of ATP was found to be 3.5 μM. Fluorescence, circular dichroism and melting temperature (Tm) experiments were carried out to confirm the binding specificity and structural changes. The second method employs the ratiometric fluorescent approach based on the Forster resonance energy transfer (FRET) for the detection of ATP using berberine along with a quencher (AuNRs, AgNPs) and a fluorophore (red quantum dots (RQDs), carbon dots (CDs)) labeled at 5′ and 3′ termini of the ATP-binding aptamer sequence. Upon addition of ATP and berberine, ATP specifically binds with its aptamer leading to the formation of G-quadruplex, and similarly, berberine also binds to the G-quadruplex. This leads to an enhancement of fluorescence of berberine while that of RQD and CDs were significantly quenched via FRET. The respective detection limits calculated were 3.6 μM and 3.8 μM, indicating these fluorescent aptasensor methods may be used for a wide variety of small molecules.
关键词： Aptasensor,Adenosine-5′-triphosphate,Gold nanorods,Fluorescence,FRET,Berberine
更新于2025-09-23 15:22:29
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Optical aptasensor based on silver nanoparticles for the colorimetric detection of adenosine
摘要： A new and straightforward optical sensor for the colorimetric determination of adenosine (AD) in human urine samples was developed. The sensor comprised silver nanoparticles (AgNPs) as colorimetric elements and anti-AD aptamer (AP) as a recognition probe. In a solution containing AD and high concentration of NaCl, due to the unique binding of AD with AP, the aggregated metal nanomaterials dispersed in the solution, and the color intensity of the solution was changed accordingly. The absorbance of the solution was monitored for AD quantification. The method was applicable for the determination of AD in the concentration range of 60–280 nM with the detection limit of 21 nM. The relative standard deviation ranged from 4.8 to 8.8% for six replicates. The method showed excellent selectivity toward AD checked over some probable interfering compounds. To investigate the performance of AgNPs, the analytical characteristics of the method including linear range, detection limit, selectivity, and precision were compared with those obtained by a common AuNPs-based aptasensor. The reliability of the method was further ascertained for the detection of AD in urine samples of two lung cancer patients with percentage recoveries in the range of 98–107%.
关键词： Adenosine,Silver nanomaterials,Colorimetric,UV–vis absorption spectroscopy,Aptamer
更新于2025-09-23 15:22:29
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Raman Spectroscopic Analysis of Signaling Molecules–Dopamine Receptors Interactions in Living Cells
摘要： The selective interaction of signaling compounds including neurotransmitters and drugs with the dopamine receptors (DARs) is extremely important for the treatment of neurodegenerative diseases. Here, we report a method to probe the selective interactions of signaling compounds with D1 and D2 DARs in living cells using the combined approach of theoretical calculation and surface-enhanced Raman spectroscopy (SERS). When signaling compounds such as DA, amphetamine, methamphetamine, and methylenedioxypyrovalerone interact with D1 dopamine receptors (DRD1), the intracellular cyclic adenosine monophosphate (cAMP) level is increased. However, the intracellular level of cAMP is decreased when D2 dopamine receptors (DRD2) interact with the abovementioned signaling compounds. In our experiments, we have internalized the silica-coated silver nanoparticles (AgNP@SiO2) in living cells to adsorb biologically generated cAMP which was probed by using SERS. Besides adsorptions of cAMP, AgNP@SiO2 has a crucial role for the enhancement of Raman cross section of the samples. We observed the characteristic SERS peaks of cAMP when DRD1-overexpressed cells interact with the signaling compounds; these peaks were not observed for other cells including DRD2-overexpressed and DRD1?DRD2-coexpressed cells. Our experimental approach is successful to probe the intracellular cAMP and characterize the selectivity of signaling compounds to different types of DARs. Furthermore, our experimental approach is highly capable for in vivo studies because it can probe intracellular cAMP using a low input power of incident laser without significant cell damage. Our experimental results and density functional theory calculations showed that 780 and 1503 cm?1 are signature Raman peaks of cAMP. The SERS peak at 780 cm?1 is associated with C?O, C?C, and C?N stretching and symmetric and asymmetric bending of two O?H bonds of cAMP, whereas the SERS peak at 1503 cm?1 is contributed by the O9?H3 bending mode.
关键词： cyclic adenosine monophosphate,living cells,signaling compounds,dopamine receptors,surface-enhanced Raman spectroscopy
更新于2025-09-23 15:21:21
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Novel fluorescent triazinobenzimidazole derivatives as probes for labelling human A1 and A2B adenosine receptor subtypes
摘要： The expression levels and the subcellular localization of adenosine receptors (ARs) are affected in several pathological conditions as a consequence of changes in adenosine release and metabolism. In this respect, labelled probes able to monitor the AR expression could be a useful tool to investigate different pathological conditions. Herein, novel ligands for ARs, bearing the fluorescent 7-nitrobenzofurazan (NBD) group linked to the N1 (1,2) or N10 (3,4) nitrogen of a triazinobenzimidazole scaffold, were synthesized. The compounds were biologically evaluated as fluorescent probes for labelling A1 and A2B AR subtypes in bone marrow-derived mesenchymal stem cells (BM-MSCs) that express both receptor subtypes. The binding affinity of the synthetized compounds towards the different AR subtypes was determined. The probe 3 revealed a higher affinity to A1 and A2B ARs, showing interesting spectroscopic properties, and it was selected as the most suitable candidate to label both AR subtypes in undifferentiated MSCs. Florescence confocal microscopy showed that compound 3 significantly labelled ARs on cell membranes and the fluorescence signal was decreased by the cell pre-incubation with the A1 AR and A2B AR selective agonists, R-PIA and BAY 60-6583, respectively, thus confirming the specificity of the obtained signal. In conclusion, compound 3 could represent a useful tool to investigate the expression pattern of both A1 and A2B ARs in different pathological and physiological processes. Furthermore, these results provide an important basis for the design of new and more selective derivatives able to monitor the expression and localization of each different ARs in several tissues and living cells.
关键词： triazinobenzimidazole derivatives,Adenosine receptors,fluorescent probes,mesenchymal stem cells,A2B AR subtype
更新于2025-09-23 15:21:01
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New Strategy to Preserve Phosphate by Ionic Liquid Matrices in Matrix-Assisted Laser Desorption/Ionization: A Case of Adenosine Nucleotides
摘要： Adenosine -5'-triphosphate (ATP) plays a valuable role in metabolic activity to produce adequate energy in a biosystem. A high ATP/AMP ratio has a correlation with diabetes that induces suppression of AMP-activated protein kinase (AMPK). Matrix-assisted laser desorption/ionization (MALDI)–mass spectrometry (MS) has outstanding potential in determining the ratio of several types of adenosine phosphates in a sample to rapidly understand the primary energy transfer in metabolism. Although MALDI is viewed as a soft ionization technique for MS analysis, excess photon energy might crack the phosphate bonds leading to misinterpretation of the ATP level. In this work, ionic liquid matrices (ILMs) were employed to reduce fragmentation and increase the detection e?ciency during the MALDI process. This study demonstrated for the ?rst time that 2,5-dihydroxybenzoic acid pyridine (DHBP) is one of the most e?ective matrices for further quantitative analysis of adenosine nucleotides. This systematic screening of ILMs also enhances the fundamental understanding of MALDI.
关键词： Adenosine,ionic liquid matrix,AMPK,triphosphate,soft ionization,ionic liquids,ATP,nucleotides,MALDI
更新于2025-09-23 15:19:57
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Chemical Synthesis and Characterization of Poly(poly(ethylene glycol) methacrylate)-Grafted CdTe Nanocrystals via RAFT Polymerization for Covalent Immobilization of Adenosine
摘要： This paper describes the functionalization of poly(poly(ethylene glycol) methacrylate) (PPEGMA)-grafted CdTe (PPEGMA-g-CdTe) quantum dots (QDs) via surface-initiated reversible addition–fragmentation chain transfer (SI-RAFT) polymerization for immobilization of adenosine. Initially, the hydroxyl-coated CdTe QDs, synthesized using 2-mercaptoethanol (ME) as a capping agent, were coupled with a RAFT agent, S-benzyl S'-trimethoxysilylpropyltrithiocarbonate (BTPT), through a condensation reaction. Then, 2,2'-azobisisobutyronitrile (AIBN) was used to successfully initiate in situ RAFT polymerization to generate PPEGMA-g-CdTe nanocomposites. Adenosine-above-PPEGMA-grafted CdTe (Ado-i-PPEGMA-g-CdTe) hybrids were formed by the polymer shell, which had successfully undergone bioconjugation and postfunctionalization by adenosine (as a nucleoside). Fourier transform infrared (FT-IR) spectrophotometry, energy-dispersive X-ray (EDX) spectroscopy, thermogravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy results indicated that a robust covalent bond was created between the organic PPEGMA part, cadmium telluride (CdTe) QDs, and the adenosine conjugate. The optical properties of the PPEGMA-g-CdTe and Ado-i-PPEGMA-g-CdTe hybrids were investigated by photoluminescence (PL) spectroscopy, and the results suggest that they have a great potential for application as optimal materials in biomedicine.
关键词： poly(poly(ethylene glycol methacrylate),CdTe quantum dots,adenosine,SI-RAFT,covalent immobilization
更新于2025-09-19 17:15:36
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Spectrophotometric, fluorimetric and electrochemical selective pyrophosphate/ATP sensing based on the dimethyltin(IV)-tiron system
摘要： Sensing of pyrophosphate anion (PPi) in the presence of nucleotide triphosphates allows the real time monitoring of the polymerase chain reaction. To get a deeper understanding of the factors involved in PPi/nucleotide triphosphate discrimination, a detailed study on the performance of a dimethyltin(IV)-catecholate complex capable of both separate fluorimetric or electrochemical detection of PPi in the presence of adenosine triphosphate (ATP) has been undertaken. Dimethyltin(IV) tightly binds PPi or ATP, and forms a stable 1:1 complex with tiron (4,5-dihydroxy-1,3-benzenedisulfonic acid) in water. The complexation equilibria with all components are characterized quantitatively by potentiometric and spectroscopic titrations. Pyrophosphate anion can be detected owing to its ability to release free tiron from the complex by measuring either a fluorimetric or an electrochemical signal. On the contrary, ATP does not displace tiron but causes an interference with PPi in the fluorimetric detection method due to the formation of a ternary Me2Sn(IV)-tiron-ATP complex with optical properties intermediate between those of free and bound tiron. In the electrochemical (square wave voltammetry) method, the ternary ATP complex shows a separate peak which does not coincide with the peaks of neither free nor bound tiron, thus making possible the simultaneous detection of ATP in addition to PPi.
关键词： optical sensing,dimethyltin(IV),pyrophosphate,electrochemical sensing,adenosine triphosphate selectivity,tiron
更新于2025-09-19 17:15:36
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Split aptamer based sensing platform for adenosine deaminase detection by fluorescence resonance energy transfer
摘要： In this paper, a split aptamer based fluorescence resonance energy transfer (FRET) platform was constructed for the determination of adenosine deaminase (ADA) activity by using gold nanoclusters (AuNCs) and gold nanoparticles (AuNPs). A single adenosine triphosphate (ATP) aptamer was split into two fragments (referred to as P1 and P2). P1 was covalently attached to the AuNCs at the 5′ end (P1-AuNCs), and P2 was labeled with AuNPs at the 3′ end (P2-AuNPs). In the presence of ATP, ATP bound with the two fragments with high affinity to link P1-AuNCs and P2-AuNPs together, thus the fluorescence of P1-AuNCs was quenched via FRET from P1-AuNCs to P2-AuNPs. With the addition of ADA, ATP was transformed into inosine triphosphate (ITP), and then P1 and P2 were released to cause the fluorescence recovery of the system. So a split aptamer based FRET platform for ADA detection can be established via the fluorescence intensity change of the system. This platform showed a good linear relationship between the fluorescence intensity and ADA concentration in the range of 2-120 U L-1, and the limit of detection (LOD) was 0.72 U L-1. Moreover, the detection of ATP in human serum sample demonstrated the accuracy and applicability of the method for ADA detection in real sample.
关键词： Split aptamer,Gold nanoclusters,Adenosine deaminase,Fluorescence,Gold nanoparticles
更新于2025-09-19 17:15:36
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3D Ultrasensitive Polymers-Plasmonic Hybrid Flexible Platform for In-Situ Detection
摘要： This paper introduces a three-dimensional (3D) pyramid to the polymers-plasmonic hybrid structure of polymethyl methacrylate (PMMA) composite silver nanoparticle (AgNPs) as a higher quality flexible surface-enhanced Raman scattering (SERS) substrate. Benefiting from the effective oscillation of light inside the pyramid valley could provide wide distributions of 3D 'hot spots' in a large space. The inclined surface design of the pyramid structure could facilitate the aggregation of probe molecules, which achieves highly sensitive detection of rhodamine 6G (R6G) and crystal violet (CV). In addition, the AgNPs and PMMA composite structures provide uniform space distribution for analyte detection in a designated hot spot zone. The incident light can penetrate the external PMMA film to trigger the localized plasmon resonance of the encapsulated AgNPs, achieving enormous enhancement factor (~6.24 × 108). After undergoes mechanical deformation, the flexible SERS substrate still maintains high mechanical stability, which was proved by experiment and theory. For practical applications, the prepared flexible SERS substrate is adapted to the in-situ Raman detection of adenosine aqueous solution and the methylene-blue (MB) molecule detection of the skin of a fish, providing a direct and nondestructive active-platform for the detecting on the surfaces with any arbitrary morphology and aqueous solution.
关键词： PMMA,AgNPs,adenosine,SERS,methylene-blue,in-situ
更新于2025-09-19 17:13:59