Monitoring and determination of ultra-trace concentrations of monoamine neurotransmitter such as noradrenaline (NA) in living cells with simple, sensitive and selective assays are significantly interesting. We design NA-electrode sensing system based on C-, N-doped NiO broccoli-like hierarchy (CNNB). The spherical broccoli-head umbrella architectures associated with nano-tubular arrangements enabled to tailor NA biosensor design. The homogenous doping and anisotropic dispersion of CN nanospheres along the entire NB head nanotubes lead to creating of abundant electroactive sites in the interior tubular vessels and outer surfaces for ultrasensitive detection of NA in living cells such as PC12. The CNNB biosensor electrodes showed efficient electrocatalytic activity, enhanced kinetics for electrooxidation of NA, and fast electron-transfer between electrode-electrolyte interface surfaces, enabling synergistic enhancement in sensitivity, and selectivity at a low-detectable concentration of ∼ 6nM and reproducibility of broccoli-shaped NA-electrodes. The integrated CNNB biosensor electrodes showed evidence of monitoring and screening of NA released from PC12 cells under K ion-extracellular stimulation process. The unique features of CNNB in terms of NA-selectivity among multi-competitive components, long-term stability during the detection of NA may open their practical, in-vitro application for extracellular monoamine neurotransmitters detection in living cells.

E m r a n , M o h a m m e d Y., Kh alifa, H e s h a m , Go m a a , H a s s a ni e n, S h e n a s h e n , M o h a m e d A., Akh t ar, N a e e m , M e k a wy, M o a t a z, F a h e e m , Ah m e d a n d El-S af ty, S h e rif (2 0 1 7) Hi e r a r c hic al C-N d o p e d Ni O wit h d u al-h e a d e c hi n o p flo w e r s fo r ul t r a s e n si tiv e m o ni t o ri n g of e pi n e p h ri n e in h u m a n bloo d s e r u m . Mi c r o c hi mic a Act a, 1 8 4 (1 1). p p. 4 5 5 3-4 5 6 2. IS S N 0 0 2 6-3 6 7 2 Do w nlo a d e d fro m: h t t

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3D-ridge nanosheets of N-doped mesoporous carbon (NMCS)-based electrodes are fabricated as ultrasensitive biosensors for in vitro monitoring of dopamine (DA) released from living cells. The large-scale ranges of dense-layered sheets are arranged linearly with a thickness of <10 nm, soft tangled edges, stocked layer arrangements, and tunable mesoporous frameworks with 3D orientations. The intrinsic features of the active interfacial surface of the electrode based on NMCS along with polarized surfaces, dense surface-charged matrices, fast electron transfer, and easy molecular diffusion, are present in the highly active electrode for biosensing applications. The designed electrode based on the NMCS shows high sensitivity and selectivity for DA sensing even in the presence of physiological interference molecules, such as ascorbic acid and/or uric acid, at a low applied potential of 0.25 V versus Ag/AgCl. The large-scale NMCS-based electrode shows low detection limits as low as 10 nmol L , wide linear range up to 0.5 mmol L , long-term stability for more than 15 d (relative standard deviation (RSD)= 5.8%), and a low cytotoxicity with high biocompatibility. The findings demonstrated that the NMCS-based electrode is a reliable modified electrode for ultratrace sensitivity of DA, which is secreted normally from dopaminergic cells (PC12) or under a stimulating agent (K ).

The controlled design of hierarchical CN-ST flowers is a key feature for creating biosensor surface electrodes for photo-electrochemical, ultrasensitive screening of mono-bioactive molecules.

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The active interfacial surface of S-doped microporous carbon spheres strongly binds with ascorbic acid in food and pharmaceutical products.

The design of biosensing assay of monoamine neurotransmitters (MANTs) such as epinephrine (Ep), norepinephrine (NE), and dopamine (DA), as well as the monitoring of these MANTs released from dopaminergic cells, are of particular interest. Electrochemical sensors based on the novel construction of nickel oxides (NiO) were fabricated and employed for electrochemical screening of MANTs. A novel NiO-lacy flower-like (NLF) geometrical structure with semi-spherical head surfaces connected with a trunk as an arm was achieved. The designed semi-spherical head associated with abundant and the welldispersed tubular branches with needle-like open ends might lead to the creation of vascular vessels for facile diffusion and suitable accommodation of the released MANTs throughout active and wide-surfacearea coverage, multi-diffusive pores, and caves with connective open macro-/meso-windows along the entire top-view nanoneedles of lacy flower head and trunk. These electrode surfaces possess high-index catalytic site facets associated with the formation of ridges/defects on {110}-top-cover surface dominants for strong binding, fast response, and signaling of MANTs. The NLF-modified electrode enabled high sensitivity for MANTs and a low limit of detection of 6 nM. Ultrasensitive in-vitro monitoring of DA released from dopaminergic cells (such as PC12) was realized. The NLF electrode was used to detect MANTs from its sources (PC12), and it could be used for clinical diagnosis. .