Carbon fiber ultramicrodic electrode electrodeposited with over-oxidized polypyrrole for amperometric detection of vesicular exocytosis from pheochromocytoma cell.

Vesicular exocytosis is ubiquitous, but it is difficult to detect within the cells' communication mechanism. For this purpose, a 2 µm ultramicrodic carbon fiber electrode was fabricated in this work based on electrodeposition with over-oxidized polypyrrole nanoparticle (PPyox-CFE), which was applied successfully for real-time monitoring of quantal exocytosis from individual pheochromocytoma (PC12) cells. PPyox-CFE was evaluated by dopamine (DA) solutions through cyclic voltammetry and amperometry electrochemical methods, and results revealed that PPyox-CFE improved the detection limit of DA. In particular, the sensitivity of DA was improved to 24.55 µA·µM(-1)·µm(-2) using the PPyox-CFE. The ultramicrodic electrode combined with the patch-clamp system was used to detect vesicular exocytosis of DA from individual PC12 cells with 60 mM K+ stimulation. A total of 287 spikes released from 7 PC12 cells were statistically analyzed. The current amplitude (Imax) and the released charge (Q) of the amperometric spikes from the DA release by a stimulated PC12 cell is 45.1 ± 12.5 pA and 0.18 ± 0.04 pC, respectively. Furthermore, on average ~562,000 molecules were released in each vesicular exocytosis. PPyox-CFE, with its capability of detecting vesicular exocytosis, has potential application in neuron communication research.

Integrated Three-Electrode Dual-Mode Detection Chip for Place Cell Analysis: Dopamine Facilitates the Role of Place Cells in Encoding Spatial Locations of Novel Environments and Rewards.

The functioning of place cells requires the involvement of multiple neurotransmitters, with dopamine playing a critical role in hippocampal place cell activity. However, the exact mechanisms through which dopamine influences place cell activity remain largely unknown. Herein, we present the development of the integrated three-electrode dual-mode detection chip (ITDDC), which enables simultaneous recording of the place cell activity and dopamine concentration fluctuation. The working electrode, reference electrode, and counter electrode are all integrated within the ITDDC in electrochemical detection, enabling the real-time in situ monitoring of dopamine concentrations in animals in motion. The reference, working, and counter electrodes are surface-modified using PtNPs and polypyrrole, PtNPs and PEDOT:PSS, and PtNPs, respectively. This modification allows for the detection of dopamine concentrations as low as 20 nM. We conducted dual-mode testing on mice in a novel environment and an environment with food rewards. We found distinct dopamine concentration variations along different paths within a novel environment, implying that different dopamine levels may contribute to spatial memory. Moreover, environmental food rewards elevate dopamine significantly, followed by the intense firing of reward place cells, suggesting a crucial role of dopamine in facilitating the encoding of reward-associated locations in animals. The real-time and in situ recording capabilities of ITDDC offer new opportunities to investigate the interplay between electrophysiology and dopamine during animal exploration and reward-based memory and provide a novel glimpse into the correlation between dopamine levels and place cell activity.

Adequate Silicone Oil Tamponade by Utilizing the Space of Anterior Segment for Complicated Retinal Detachment: Technique, Efficacy, and Safety.

PURPOSE: To evaluate the efficacy and safety of adequate silicone oil (SO) tamponade procedure in patients with complicated retinal detachment. METHODS: Thirty-one eyes in 31 patients were enrolled in this prospective case series. Adequate SO tamponade was performed by injecting the SO into the vitreous cavity and the entire anterior chamber, followed by posterior capsulotomy and inferior peripheral iridotomy. Preoperative and follow-up data including retinal anatomic reattachment and SO status, best-corrected visual acuity, intraocular pressure, surgical complications and management were collected and analyzed. RESULTS: Twenty-nine eyes presented with complete retinal reattachment after subsequent SO removal with a primary success rate of 93.5%. Seventeen patients (54.8%) had complete anterior chamber SO migration to the vitreous cavity within the first postoperative day. The average time for anterior chamber SO migration was 2.3 ±â€Š1.8 days. No oil-fluid interface in the vitreous cavity was observed in all the eyes, indicating a relatively adequate SO tamponade. Acute intraocular pressure elevation occurred in 16 (51.6%) eyes and was controllable under medication (n = 16) and anterior chamber paracentesis (n = 1). Two patients developed recurrent retinal detachment and received SO removal and a secondary adequate SO tamponade. At final follow-up, all the eyes had SO removal for at least 3 months and retinas maintained completely attached. CONCLUSIONS: The adequate SO tamponade procedure offers a simple, safe, and efficacious treatment alternative for complicated retinal detachment.

PtNPt/MWCNT-PEDOT:PSS-Modified Microelectrode Arrays for the Synchronous Dopamine and Neural Spike Detection in Rat Models of Sleep Deprivation.

In this study, a biosensor assembly based on microelectrode arrays (MEAs) modified with PtNPt/MWCNT-PEDOT:PSS nanocomposites is presented to synchronously detect the dopamine (DA) and electrophysiological activities in rat brains. Different morphological and electrochemical characterizations were conducted to show the excellent mechanical and electrical properties of the as-prepared probes. The developed biosensors realized the sensitive and selective detection of DA with the existence of significant interferences such as uric acid (UA), ascorbic acid (AA), glutamate (Glu), and 3,4-dihydroxyphenylacetic acid (DOPAC). Calibration curve for the DA response was linear with the concentration from 0.05 µM to 79 µM (R = 0.999), with a sensitivity of 30.561 pA/µM and detection limit as low as 50 nM. Finally, the proposed microelectrode was applied to be implanted into the cortex and caudate putamen (CPU) of rats, which was demonstrated to stably measure the synchronous neurochemical and neurophysiological changes caused by 72 h sleep deprivation. The in vivo measuring results showed that the sleep deprivation increased the DA release and neural spike activity in both cortex and CPU. The local field potential (LFP) power in the delta and theta band was significantly increased as well. These changes in brain may reflect the brain's adaptive reaction toward the side effects induced by sleep deprivation and may partially explain the mechanism of forced wakefulness in the presence of accumulated sleep pressure.

The asymmetric synthesis of (R,R)-formoterol via transfer hydrogenation with polyethylene glycol bound Rh catalyst in PEG2000 and water.

(R,R)-formoterol was synthesized in seven steps with 4-hydroxyl-3-nitro-acetophenone as the starting material. The key intermediate, the chiral secondary alcohol 4, was prepared via Rh-catalyzed asymmetric transfer hydrogenation with (S,S)-PEGBsDPEN as the ligand and sodium formate as the hydrogen donor under mild conditions. With a mixture of PEG 2000 and water as the reaction media, the catalyst system could be recycled four times.

A Comparative Proteomics Analysis of Five Body Fluids: Plasma, Urine, Cerebrospinal Fluid, Amniotic Fluid, and Saliva.

PURPOSE: Body fluid is considered a rich source of disease biomarkers. Proteins in many body fluids have potential clinical applications for disease diagnostic and prognostic predictions. EXPERIMENTAL DESIGN: To determine differences in the protein components and functional features of body fluids, a proteomic comparison of five body fluids (plasma, urine, cerebrospinal fluid, saliva, and amniotic fluid) was conducted by high-resolution mass spectrometry. RESULTS: A total of 4717 nonredundant proteins were identified, and the concentrations of 3433 proteins were estimated by an intensity-based algorithm quantitation method. Among them, 564 proteins were shared among the five body fluids, with common functions in the coagulation/prothrombin system and inflammatory response. A total of 36.7% of the proteins were detected in only one body fluid and were closely related to their adjacent tissues by function. The functional analysis of the remaining 2986 proteins showed that similar functions might be shared among different body fluids, which highlighted intimate connection in the body. CONCLUSIONS AND CLINICAL RELEVANCE: The quantitative comparative functional analysis indicated that body fluids might reflect the diverse functions of the whole body rather than the characteristics of their adjacent tissues. The above data might indicate the potential application of body fluids for biomarker discovery.