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Synthesis of Multi-mode Quantum Dots Encoded Molecularly Imprinted Polymers Microspheres and Application in Quantitative Detection for Dopamine
摘要： As the promising analytical strategy, multi-mode quantum dots (QDs) encoded molecularly imprinted fluorescent sensors have attracted considerable attention. Here, a novel encoding strategy for water-dispersed QDs molecularly imprinted polymers microspheres (MIPMs) with a high-performance fluorescence intensity and multi-color signal was established. The water-compatible MIPMs were firstly synthesized via integrating the reversible addition-fragmentation chain transfer and precipitation polymerization (RAFT-PP), which could improve the water compatibility by grafting the hydrophilic groups of poly(2-hydroxyrthyl methacrylate) (PHEMA). Then the water-compatible MIPMs were used as embedding matrix to separately incorporate five different QDs, and a series of multi-color QDs encoded MIPs (five single-color and 10 dual-color fluorescent systems) were obtained. The fluorescent characterization of encoded MIPMs was studied in detail. Further, dual-mode fluorescent sensors, including monochromatic and ratiometric, were successfully fabricated for the quantitative detection of dopamine; good linear response in the range of 5-300 μg L-1 and 1-100 μg L-1 and the limit of detection (LOD) with 2 μg L-1 and 0.5 μg L-1 were obtained for monochromatic and ratiometric sensor, respectively. It is the first time to introduce the optical encoding strategy into the fabrication of fluorescent MIPs, which not only greatly simplifies the preparation process of fluorescent imprinted sensor, but also provides more alternatives for the detection method of analyte and the potential of high-throughput multiple analytes at one time.
关键词： Molecularly imprinted polymer,Quantum dot,Fluorescent sensor,Dopamine,Encoded microspheres
更新于2025-09-19 17:13:59
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Positron emission tomography/computed tomography dual imaging using 18-fluorine flurodeoxyglucose and 11C-labeled 2-?2-carbomethoxy-3-?2-(4-fluorophenyl) tropane for the severity assessment of Parkinson disease
摘要： The value of dual imaging mode for the severity assessment of Parkinson disease (PD) is explored by conducting positron emission tomography computed tomography (PET/CT) double imaging using combined 18-fluorine flurodeoxyglucose (18F-FDG) brain metabolism and 11C-2b-carbomethoxy-3b-(4-fluorophenyl) tropane (11C-CFT) brain dopamine transporter (DAT). A total of 102 patients with PD and 50 healthy people in the control group are enrolled for the PET/CT dual imaging of 18F-FDG brain metabolism and 11C-CFT brain DAT. The characteristics of 18F-FDG PET/CT and 11C-CFT PET/CT imaging are analyzed by delineating the region of interest. Differences in the glucose metabolism and DAT distribution in the basal ganglia of patients with PD and healthy control group in the PET/CT imaging and the radioactive distribution characteristics of cerebral cortex in glucose metabolism imaging are compared. The characteristics of PET/CT imaging of 11C-CFT brain DAT in the ganglion region in absorbing 11C-CFT in different PD groups are analyzed. Compared with the healthy control group, changes in the cerebral glucose metabolism in the PD group mainly occur due to the increased symmetry metabolism of the nucleus of bilateral basal ganglia and the decreased metabolism of the cerebral cortex as shown in the 18F-FDG PET/CT images. With disease progression, the bilateral parietal, frontal, temporal, and occipital leaves showed different degrees of FDG metabolism. Statistically significant difference is observed for the11C-CFT absorption among the caudate nucleus and the anterior, middle, and posterior nuclei of the bilateral basal ganglia of the PD and healthy control groups. In the PD group, the bilateral caudate nucleus and the anterior, middle, and posterior parts of the putamen show decreased DAT distribution. Regardless of unilateral or bilateral symptoms, the DAT distribution in the nucleus of the contralateral basal ganglia and in the posterior part of the nucleus is substantially reduced. PET/CT dual imaging by 18F-FDG PET/CT combined with 11C-CFT PET/CT features high application value for the severity assessment of PD.
关键词： brain metabolism,dopamine transporter,computed tomography of electron emission,Parkinson disease
更新于2025-09-19 17:13:59
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Simultaneous determination of ascorbic acid, dopamine, and uric acid using graphene quantum dots/ionic liquid modified screen-printed carbon electrode
摘要： In this work, graphene quantum dots (GQDs) and ionic liquid (IL) modified screen-printed carbon electrode (GQDs/IL-SPCE) were introduced for the simultaneous determination of ascorbic acid (AA), dopamine (DA) and uric acid (UA). GQDs were synthesized by directly pyrolyzing citric acid and then dropped onto the surface of IL-SPCE, which was prepared by screen-printing the mixture of IL and carbon ink on a portable substrate. UV-Vis spectrophotometry, fluorescence spectrophotometry, transmission electron microscopy (TEM), scanning electron microscopy (SEM), cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS) were used to characterize the synthesized GQDs and the modified electrodes. The GQDs/IL-SPCE exhibited excellent electrocatalytic activity for the oxidation of AA, DA, and UA in the mixture solution. Moreover, the anodic peak responses of these three analytes were also resolved into three well-defined peaks. Under the optimized conditions, the linear response ranges for AA, DA, and UA were 25 - 400 μM, 0.2 - 10 μM, and 0.5 - 20 μM, respectively, with low detection limits (σ/N = 3) of 6.64 μM, 0.06 μM, and 0.03 μM, respectively. The proposed sensor exhibited high sensitivity, low cost and successfully applied for the simultaneous detection of AA, DA, and UA in pharmaceutical products and biological samples.
关键词： Graphene quantum dots,Uric acid,Dopamine,Screen-printed carbon electrode,Ionic liquid,Ascorbic acid
更新于2025-09-19 17:13:59
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One Pot Aqueous Synthesis of L-Histidine Amino Acid Capped Mn: ZnS Quantum Dots for Dopamine Sensing
摘要： Background: Mn doped ZnS is selected as the right element which is prominent among quantum dot for its high luminescent and quantum yield property and also non toxicity while comparing with other organometallic quantum dot synthesized by using different capping agents. Methods: An interesting observation based on colorimetric sensing of dopamine using manganese doped zinc sulfide quantum dot is discussed in this study. Mn doped ZnS quantum dot surface passivated with capping agents such as L-histidine and also in polymers like chitosan, PVA and PVP were studied and compared. The tunable fluorescence effect was also observed in different polymers and amino acid as capping agents. Optical characterization studies like UV-Visible spectroscopy and PL spectroscopy have been carried out. The functional group modification of Quantum dot has been analyzed using FTIR and size and shape analysis was conducted by using HRTEM image. Results: The strong and broad peak of FTIR in the range of 3500-3300 cm-1 confirms the presence of O-H bond. It is also observed that quenching phenomena in the luminescent peak are due to weaker confinement effect. The average size of the particle is shown to be around 4-5 nm. Changes in color of the quantum dot solution from transparent to dark brown has been due to the interaction with dopamine. Conclusion: Finally, L-Histidine amino acid capped Mn:ZnS shows better results in luminescence and size confinement properties. Hence, it was chosen for dopamine sensing due to its colloidal nature and inborn affinity towards dopamine, a neurotransmitter which is essential for early diagnosis of neural diseases.
关键词： dopamine,Quantum dots,confinement,quenching,fluorescence,amino acid,capping agent
更新于2025-09-19 17:13:59
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Depth-resolved fiber photometry with a single tapered optical fiber implant
摘要： Fiber photometry is increasingly utilized to monitor fluorescent sensors of neural activity in the brain. However, most implementations are based on flat-cleaved optical fibers that can only interface with shallow tissue volumes adjacent to the fiber. We exploit modal properties of tapered optical fibers (TFs) to enable light collection over an extent of up to 2 mm of tissue and multisite photometry along the taper. Using a single TF, we simultaneously observed distinct dopamine transients in dorsal and ventral striatum in freely moving mice performing a simple, operant conditioning task. Collection volumes from TFs can also be engineered in both shape and size by microstructuring the nonplanar surface of the taper, to optically target multiple sites not only in the deep brain but, in general, in any biological system or organ in which light collection is beneficial but challenging because of light scattering and absorption.
关键词： neural activity,tapered optical fibers,dopamine transients,fiber photometry,multisite photometry
更新于2025-09-16 10:30:52
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Covalently assembled dopamine nanoparticle as an intrinsic photosensitizer and pH-responsive nanocarrier for potential application in anticancer therapy
摘要： We report a novel nanophotosensitizer via one-step covalent assembly of dopamine and genipin. This is the first report unveiling the photodynamic effect of dopamine-based materials. These nanophotosensitizers can also act as pH-responsive drug nanocarriers via a catechol–boronate linkage, thus achieving combined PDT and chemotherapy for highly efficient cancer treatment.
关键词： nanophotosensitizer,genipin,nanocarrier,dopamine,pH-responsive,chemotherapy,photodynamic therapy
更新于2025-09-12 10:27:22
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Simply synthesized nitrogen-doped graphene quantum dot (NGQD)-modified electrode for the ultrasensitive photoelectrochemical detection of dopamine
摘要： Recently, nitrogen-doped graphene quantum dots (NGQDs), as a new type of quantum semiconductor and photoelectrochemical material, are promising candidates in photoelectric sensing, water splitting, and biological imaging and have various potential application prospects. In this work, NGQDs were prepared by a simple calcination method, and then a photoelectrochemical sensing platform based on the NGQDs electrode with superior photoelectrochemical activity was designed and fabricated for the detection of dopamine (DA). Benefitting from the quantum effect and size effect, NGQDs displayed an enhanced photocurrent effective within ultra-low detection limit (0.03 μm), wide detection range (0.03–450 and 450–9680 μm), and high sensitivity in detecting DA with the assistance of ultraviolet light irradiation. The NGQDs electrode also showed continuous and stable photocurrent densities after long-term experiment, indicating the excellent durability of NGQDs for DA detection.
关键词： ultrasensitive detection,NGQDs,photoelectrochemistry,dopamine
更新于2025-09-11 14:15:04
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Molecularly Imprinted Fluorescent Test Strip for Direct, Rapid, and Visual Dopamine Detection in Tiny Amount of Biofluid
摘要： Paper-based assays for detection of physiologically important species are needed in medical theranostics owning to their superiorities in point of care testing, daily monitoring, and even visual readout by using chromogenic materials. In this work, a facile test strip is developed for visual detection of a neurotransmitter dopamine (DA) based on dual-emission fluorescent molecularly imprinted polymer nanoparticles (DE-MIPs). The DE-MIPs, featured with tailor-made DA affinity and good anti-interference, exhibit DA concentration-dependent fluorescent colors, due to the variable ratios of dual-emission fluorescence caused by DA binding and quenching. By facile coating DE-MIPs on a filter paper, the DA test strips are obtained. The resultant test strip, like the simplicity of a pH test paper, shows the potential for directly visual detection of DA levels just by dripping a tiny amount of biofluid sample on it. The test result of real serum samples demonstrates that the DA strip enables to visually and semiquantitatively detect DA within 3 min by using only 10 μL of serum samples and with a low detection limit ((100–150) × 10?9 m) by naked eye. This work thus offers a facile and efficient strategy for rapid, visual, and on-site detection of biofluids in clinic.
关键词： molecular imprinting,dual-emission fluorescence,visual detection,paper-based assays,dopamine
更新于2025-09-10 09:29:36
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Application of spectroelectroanalysis for the quantitative determination of mixtures of compounds with highly overlapping signals
摘要： The amount of qualitative and quantitative information provided by a UV?vis absorption spectroelectrochemistry (SEC) experiment is sometimes wasted. However, almost all electrochemical and spectroscopic data can provide valuable information. In this spirit, the main objective proposed in this work is the quantitative resolution of catechol/dopamine (CAT/DA) and dopamine/epinephrine (DA/EP) mixtures, using spectroelectrochemical sensors in long optical path length arrangement based on bare optical fibers in parallel configuration with respect to carbon nanotubes or screen-printed electrodes. These compounds show extremely similar electrochemical and spectroscopic responses at high acidic pH, being impossible to determine their concentrations in the mixtures just using univariate regression models. To our knowledge, the SEC ability to resolve complex mixtures has never been demonstrated before with signals with this degree of overlapping. The quantitative analysis of these mixtures is possible using multivariate regression analysis of a set of time-resolved spectroelectrochemical data with a powerful statistical tool such as parallel factor analysis (PARAFAC). PARAFAC enables us to extract all the information from the experiments, allowing us to quantify the different analytes in mixtures of varying concentrations with excellent results. This milestone for spectroelectroanalysis illustrates the expected capabilities of SEC and demonstrates experimentally the potential of this technique for sensing of biomolecules.
关键词： screen-printed electrodes,dopamine,optical fibers,epinephrine,carbon nanotubes,spectroelectrochemistry
更新于2025-09-10 09:29:36
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Orexin-A Suppresses Signal Transmission to Dopaminergic Amacrine Cells From Outer and Inner Retinal Photoreceptors
摘要： The neuropeptides orexin-A and orexin-B are widely expressed in the vertebrate retina; however, their role in visual function is unclear. This study investigates whether and how orexins modulate signal transmission to dopaminergic amacrine cells (DACs) from both outer retinal photoreceptors (rods and cones) and inner retinal photoreceptors (melanopsin-expressing intrinsically photosensitive retinal ganglion cells [ipRGCs]). A whole-cell voltage-clamp technique was used to record light-induced responses from genetically labeled DACs in ?at-mount mouse retinas. Rod and cone signaling to DACs was con?rmed pharmacologically (in wild-type retinas), whereas retrograde melanopsin signaling to DACs was isolated either pharmacologically (in wild-type retinas) or by genetic deletion of rod and cone function (in transgenic mice). Orexin-A attenuated rod/cone-mediated light responses in the majority of DACs and inhibited all DACs that exhibited melanopsin-based light responses, suggesting that exogenous orexin suppresses signal transmission from rods, cones, and ipRGCs to DACs. In addition, orexin receptor 1 antagonist SB334867 and orexin receptor 2 antagonist TCS OX229 enhanced melanopsin-based DAC responses, indicating that endogenous orexins inhibit signal transmission from ipRGCs to DACs. We further found that orexin-A inhibits melanopsin-based DAC responses via orexin receptors on DACs, whereas orexin-A may modulate signal transmission from rods and cones to DACs through activation of orexin receptors on DACs and their upstream neurons. Our results suggest that orexins could in?uence visual function via the dopaminergic system in the mammalian retina.
关键词： orexin,dopamine,ipRGC,melanopsin,amacrine cell,retina
更新于2025-09-09 09:28:46