In this paper, we report the optoelectronic properties of multi-layered GeS nanosheet (∼28 nm thick)-based field-effect transistors (called GeS-FETs). The multi-layered GeS-FETs exhibit remarkably high photoresponsivity of Rλ ∼ 206 A W(-1) under 1.5 μW cm(-2) illumination at λ = 633 nm, Vg = 0 V, and Vds = 10 V. The obtained Rλ ∼ 206 A W(-1) is excellent as compared with a GeS nanoribbon-based and the other family members of group IV-VI-based photodetectors in the layered-materials realm, such as GeSe and SnS2. The gate-dependent photoresponsivity of GeS-FETs was further measured to be able to reach Rλ ∼ 655 A W(-1) operated at Vg = -80 V. Moreover, the multi-layered GeS photodetector holds high external quantum efficiency (EQE ∼ 4.0 × 10(4)%) and specific detectivity (D* ∼ 2.35 × 10(13) Jones). The measured D* is comparable to those of the advanced commercial Si- and InGaAs-based photodiodes. The GeS photodetector also shows an excellent long-term photoswitching stability over a long period of operation (>1 h). These extraordinary properties of high photocurrent generation, broad spectral range, and long-term stability make the GeS-FET photodetector a highly qualified candidate for future optoelectronic applications.

The concentration gradient of K across the cell membrane of a neuron determines its resting potential and cell excitability. During neurotransmission, the efflux of K from the cell via various channels will not only decrease the intracellular K content but also elevate the extracellular K concentration. However, it is not clear to what extent this change could be. In this study, we developed a multiple-parallel-connected silicon nanowire field-effect transistor (SiNW-FET) modified with K-specific DNA-aptamers (aptamer/SiNW-FET) for the real-time detection of the K efflux from cultured cortical neurons. The aptamer/SiNW-FET showed an association constant of (2.18 ± 0.44) × 10 M against K and an either less or negligible response to other alkali metal ions. The α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) stimulation induced an outward current and hyperpolarized the membrane potential in a whole-cell patched neuron under a Na/K-free buffer. When neurons were placed atop the aptamer/SiNW-FET in a Na/K-free buffer, AMPA (13 μM) stimulation elevated the extracellular K concentration to ∼800 nM, which is greatly reduced by 6,7-dinitroquinoxaline-2,3-dione, an AMPA receptor antagonist. The EC of AMPA in elevating the extracellular K concentration was 10.3 μM. By stimulating the neurons with AMPA under a normal physiological buffer, the K concentration in the isolated cytosolic fraction was decreased by 75%. These experiments demonstrate that the aptamer/SiNW-FET is sensitive for detecting cations and the K concentrations inside and outside the neurons could be greatly changed to modulate the neuron excitability.

No abstract

The Zn2+ stored in the secretory vesicles of glutamatergic neurons is coreleased with glutamate upon stimulation, resulting in the elevation of extracellular Zn2+ concentration (CZn2+ex). This elevation of CZn2+ex regulates the neurotransmission and facilitates the fibrilization of amyloid‐β (Aβ). However, the exact CZn2+ex surrounding neurons under (patho)physiological conditions is not clear and the connection between CZn2+ex and the Aβ fibrilization remains obscure. Here, a silicon nanowire field‐effect transistor (SiNW‐FET) with the Zn2+‐sensitive fluorophore, FluoZin‐3 (FZ‐3), to quantify the CZn2+ex in real time is modified. This FZ‐3/SiNW‐FET device has a dissociation constant of ≈12 × 10−9m against Zn2+. By placing a coverslip seeded with cultured embryonic cortical neurons atop an FZ‐3/SiNW‐FET, the CZn2+ex elevated to ≈110 × 10−9m upon stimulation with α‐amino‐3‐hydroxy‐5‐methyl‐4‐isoxazolepropionic acid (AMPA). Blockers against the AMPA receptor or exocytosis greatly suppress this elevation, indicating that the Zn2+ stored in the synaptic vesicles is the major source responsible for this elevation of CZn2+ex. In addition, a SiNW‐FET modified with Aβ could bind Zn2+ with a dissociation constant of ≈633 × 10−9m and respond to the Zn2+ released from AMPA‐stimulated neurons. Therefore, the CZn2+ex can reach a level high enough to bind Aβ and the Zn2+ homeostasis can be a therapeutic strategy to prevent neurodegeneration.

Recording ion fluctuations surrounding biological cells with a nanoelectronic device offers seamless integration of nanotechnology into living organisms and is essential for understanding cellular activities. The concentration of potassium ion in the extracellular fluid ( ) is a critical determinant of cell membrane potential and must be maintained within an appropriate range. Alteration in can affect neuronal excitability, induce heart arrhythmias, and even trigger seizure-like reactions in the brain. Therefore, monitoring local fluctuations in real time provides an early diagnosis of the occurrence of the K+-induced pathophysiological responses. Here, we modified the surface of a silicon nanowire field-effect transistor (SiNW-FET) with K+-specific DNA-aptamers (AptK+ ) to monitor the real-time variations of in primary cultured rat embryonic cortical neurons or human embryonic stem cell-derived cardiomyocytes. The binding affinity of AptK+ to K+, determined by measuring the dissociation constant of the AptK+ –K+ complex (K d = 10.1 ± 0.9 mM), is at least 38-fold higher than other ions (e.g., Na+, Ca2+, and Mg2+). By placing cultured cortical neurons over an AptK+ /SiNW-FET device, α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) stimulation raised the dose-dependently to 16 mM when AMPA concentration was >10 μM; this elevation could be significantly suppressed by an AMPA receptor antagonist, 6,7-dinitroquinoxaline-2,3-dione. Likewise, the stimulation of isoproterenol to cardiomyocytes raised the to 6–8 mM, with a concomitant increase in the beating rate. This study utilizing a robust nanobiosensor to detect real-time ion fluctuations surrounding excitable cells underlies the importance of ion homeostasis and offers the feasibility of developing an implant device for real-time monitoring.

No abstract

Primary Pigmented lesions of the Central nervous System are rare and diverse group of entities that run the gamut from Benign to malignant[1]. Among Pigmented CNS Tumor, Primary intracranial melanomas possesses a great interest among Neurosurgeons with its varied Clinical and Radiological patterns as they are most often confused and misdiagnosed with Meningioma, Schwannoma and thrombosed aneurysms . Primary cerebral melanomas, derived from the melanocytic cells that are precursor Cells of Melanoblasts considered to be originated from neural crest cells that are normally present in the leptomeninges. They are rare and occur in around 1% of all melanoma cases[2,4]. Primary intracranial malignant melanoma accounts 0.1% of intracranial neoplasms[3]. This report highlights a case of Primary Intracranial malignant melanoma of clivus in 40 year male, who has undergone left Pterional Craniotomy Trans Sylvian approach and excision of Tumor after proper dermatological, ophthalmological and systemic evaluations to exclude presence of any other lesions in the body. Which was proved malignant melanoma via Histopathology. Herein we have reported this case for its rarity and consideration as differential for prompt treatment.

Background: Hernia is an abnormal protrusion of a peritoneal lined sac through the musculo aponeurotic covering of the abdomen. The study is conducted to compare the post.operative complications in Adult Para umbilical hernia with Open Mayo's repair and Tension free Onlay prosthetic Mesh repair. Methods: A comparative 3 year study was conducted in Department of Surgery. There were 08 male and 50 female patients. They were divided into two groups-1 and 2 .Group 1 constituted 29 patients who underwent Open Mayo's repair and Group-2 constituted 29 patients who had Tension free Onlay prosthetic Mesh repair. The median follow up was 36 months. The study was conducted with special reference to the pre disposing factors, age, sex, type of operation and complications associated with it. Results: Open Mayo's repair is safe and cost effective but tension free mesh repair is also proved cost effective in terms of short hospital stay, lesser use of drugs, patient comfort and satisfaction as well as early return to normal routine work. Conclusion: Mesh repair should be considered as a first line surgical option for adult para umbilical hernias.