Construction of Dopamine-Releasing Gold Surfaces Mimicking Presynaptic Membrane by On-Chip Electrochemistry.

We report a strategy to construct a dopamine-releasing gold surface mimicking a presynaptic membrane on a microfluidic chip to simulate in vivo neural signaling. We constructed dopamine self-assembled monolayers (DA SAMs) by electrochemical deprotection of methyl group-protected DA SAMs on a gold surface. Electrochemically controllable release of DA SAMs can be realized by applying nonhydrolytic negative potential on the gold surface. Our method in constructing DA SAMs avoids the polymerization and protonation of DA molecules which may lead to the failure of the DA SAM formation. By combining microfluidics, we realized spatial and temporal controllable release of DA by electrochemistry from the gold surface. Furthermore, by culturing neurons on the patterned DA SAMs, the interface between the DA SAMs and the neurons could serve as a presynaptic membrane, and the spatiotemporal release of DA could modulate the neuron activity with high precision. Our study holds great promise in the fields of neurobiology research and drug screening.

A Wearable Fluorescence Imaging Device for Intraoperative Identification of Human Brain Tumors.

Malignant glioma (MG) is the most common type of primary malignant brain tumors. Surgical resection of MG remains the cornerstone of therapy and the extent of resection correlates with patient survival. A limiting factor for resection, however, is the difficulty in differentiating the tumor from normal tissue during surgery. Fluorescence imaging is an emerging technique for real-time intraoperative visualization of MGs and their boundaries. However, most clinical grade neurosurgical operative microscopes with fluorescence imaging ability are hampered by low adoption rates due to high cost, limited portability, limited operation flexibility, and lack of skilled professionals with technical knowledge. To overcome the limitations, we innovatively integrated miniaturized light sources, flippable filters, and a recording camera to the surgical eye loupes to generate a wearable fluorescence eye loupe (FLoupe) device for intraoperative imaging of fluorescent MGs. Two FLoupe prototypes were constructed for imaging of Fluorescein and 5-aminolevulinic acid (5-ALA), respectively. The wearable FLoupe devices were tested on tumor-simulating phantoms and patients with MGs. Comparable results were observed against the standard neurosurgical operative microscope (PENTERO® 900) with fluorescence kits. The affordable and wearable FLoupe devices enable visualization of both color and fluorescence images with the same quality as the large and expensive stationary operative microscopes. The wearable FLoupe device allows for a greater range of movement, less obstruction, and faster/easier operation. Thus, it reduces surgery time and is more easily adapted to the surgical environment than unwieldy neurosurgical operative microscopes. Clinical and Translational Impact Statement-The affordable and wearable fluorescence imaging device developed in this study enables neurosurgeons to observe brain tumors with the same clarity and greater flexibility compared to bulky and costly operative microscopes.

[Time-spatial variability of ammonium and nitrate in farmland soil of Taihu Lake region].

Time-spatial variability of ammonium and nitrate in soil profiles of farmland soil (three main paddy soils: White soil, Huangni soil and Wushan soil) during wheat and rice growth was studied. The results were as follows: the ammonium content was high in February and September and low in April and November in 2004. The spatial variability of ammonium content in soil profiles was gradually decreased from surface soil layer to bottom soil layer. It was stable below 40 cm. The nitrate content was lower than the ammonium content. The nitrate content of the wheat growth season (dry cultivation) was higher than that of the rice growth season (water cultivation) in a year. The spatial variability of the nitrate content in soil profiles was quickly decreased from surface soil layer to bottom soil layer during dry cultivation. But during the rice growth season, the nitrate content of the surface soil layer in soil profiles was lower than that of bottom soil layer. It was leaching phenomenon of nitrate. The nitrate content was in a sharp positive relation with the ammonium and changed with exponential function during dry cultivation. But there was not this relationship during water cultivation. The ammonium and nitrate were significant relation with soil organic matter in straight line. But the ammonium and nitrate content decreased with the soil clay content and pH value increased and changed with logarithmic function.