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Heavy metals in drinking water have become a severe threat to human health. Detection of heavy metals has been achieved by electrochemical sensors that are modified with complex nanocomposites; however, reproducibility of these sensors is still a big challenge when applied in commercial settings. Here, a simple, very robust, and sensitive electrochemical sensor based on a screen-printed carbon electrode modified with butterfly-shaped silver nanostructure (AgNS/SPCE) has been developed for the concurrent determination of cadmium (II), lead (II), copper (II), and mercury (II) in water samples. The electrochemical behavior of the modified electrodes was investigated using cyclic voltammetry and differential pulse anodic stripping voltammetry. The AgNS/SPCE showed distinct peak potentials and a significant increase in the peak currents for all heavy metals, attributed to the high electrical conductivity and electrocatalytic activity of the synthesized butterfly-shaped AgNS. Moreover, the excellent stability and sensitivity towards simultaneous quantification of heavy metals have been obtained with detection limits of 0.4 ppb, 2.5 ppb, 7.3 ppb, and 0.7 ppb for Cd (II), Pb (II), Cu (II), and Hg (II), respectively. Besides, the constructed sensor was successfully applied to simultaneously quantify target heavy metals in spiked water samples. Owing to excellent sensitivity, high robustness, affordability, and fast response, the presented electrochemical sensor could be incorporated into a portable and miniaturized potentiostat device, making it a promising method for on-site water analysis.

Organic electrochemical transistors formed by in operando electropolymerization of the semiconducting channel are increasingly becoming recognized as a simple and effective implementation of synapses in neuromorphic hardware. However, very few studies have reported the requirements that must be met to ensure that the polymer spreads along the substrate to form a functional conducting channel. The nature of the interface between the substrate and various monomer precursors of conducting polymers through molecular dynamics simulations is investigated, showing that monomer adsorption to the substrate produces an increase in the effective monomer concentration at the surface. By evaluating combinatorial couples of monomers baring various sidechains with differently functionalized substrates, it is shown that the interactions between the substrate and the monomer precursor control the lateral growth of a polymer film along an inert substrate. This effect has implications for fabricating synaptic systems on inexpensive, flexible substrates., Funding: Swedish Foundation for Strategic Research [RMX18-0083]; Swedish Research Council [2018-06197]; European Research Council [834677]; Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linkoping University [SFO-Mat-LiU 2009-00971]; Knut and Alice Wallenberg Foundation; Onnesjo Foundation

Mapping the entire frequency bandwidth of brain electrophysiological signals is of paramount importance for understanding physiological and pathological states. The ability to record simultaneously DC-shifts, infraslow oscillations (<0.1 Hz), typical local field potentials (0.1–80 Hz) and higher frequencies (80–600 Hz) using the same recording site would particularly benefit preclinical epilepsy research and could provide clinical biomarkers for improved seizure onset zone delineation. However, commonly used metal microelectrode technology suffers from instabilities that hamper the high fidelity of DC-coupled recordings, which are needed to access signals of very low frequency. In this study we used flexible graphene depth neural probes (gDNPs), consisting of a linear array of graphene microtransistors, to concurrently record DC-shifts and high-frequency neuronal activity in awake rodents. We show here that gDNPs can reliably record and map with high spatial resolution seizures, pre-ictal DC-shifts and seizure-associated spreading depolarizations together with higher frequencies through the cortical laminae to the hippocampus in a mouse model of chemically induced seizures. Moreover, we demonstrate the functionality of chronically implanted devices over 10 weeks by recording with high fidelity spontaneous spike-wave discharges and associated infraslow oscillations in a rat model of absence epilepsy. Altogether, our work highlights the suitability of this technology for in vivo electrophysiology research, and in particular epilepsy research, by allowing stable and chronic DC-coupled recordings.

Data and python code for reproducing the main results of the paper "Full bandwidth electrophysiology of seizures and epileptiform activity enabled by flexible graphene micro-transistor depth neural probes."

Background: In recent decades, contaminations with heavy metals ions have adversely affected the environment, food safety, and human health. Heavy metals, leaching to water sources from the industrial effluents, can enter into the aquatic and food chains of humans and animals from a variety of anthropogenic sources. Scope and Approach: Heavy metal detection has been an intensive area of research today. Both laboratory-based analytical instruments and innovative sensor devices like the electronic nose, electronic tongue, and bio/chemical sensors have increasingly emerged to meet the demand for legislative actions on environmental pollution control and early warning. These evolving technology and developments particularly in the area of nanotechnology and sensors have become key contributing factors in heavy metal detection. Key Findings and Conclusions: This endeavor aims at exploring this field in detail to understand the key principles behind this flourishing science and summarize the recent development in heavy metal detection technologies. This article also gives a brief review of commercially available portable devices that has the potential to become the next gold standard instruments in heavy metal detection.

Background: In recent decades, contaminations with heavy metals ions have adversely affected the environment, food safety, and human health. Heavy metals, leaching to water sources from the industrial effluents, can enter into the aquatic and food chains of humans and animals from a variety of anthmpogenic sources. Scope and Approach: Heavy metal detection has been an intensive area of research today. Both laboratory-based analytical instruments and innovative sensor devices like the electronic nose, electronic tongue, and bio/ chemical sensors have increasingly emerged to meet the demand for legislative actions on environmental pollution control and early warning. These evolving technology and developments particularly in the area of nanotechnology and sensors have become key contributing factors in heavy metal detection. Key Findings and Conclusions: This endeavor aims at exploring this field in detail to understand the key principles behind this flourishing science and summarize the recent development in heavy metal detection technologies. This article also gives a brief review of commercially available portable devices that has the potential to become the next gold standard instruments in heavy metal detection., Funding Agencies|Department of Biotechnology (DBT), Government of IndiaDepartment of Biotechnology (DBT) India [BT/IN/DENMARK/62/NB/2018-19]; Innovation Fund Denmark [8127-00021B]

In this research, we demonstrate a facile approach for the synthesis of a graphite-analogous layer-by-layer heterostructured CuO/ZnO/carbon paper using a graphene oxide paper as a sacrificial template. Cu2+ and Zn2+ were inserted into the interlayer of graphene oxide papers via physical absorption and electrostatic effects and then, the Mn+-graphene oxide paper was annealed in air to generate 2D nanoporous CuO/ZnO nanosheets. Due to the graphene oxide template, the structure of the obtained CuO/ZnO nanosheets with an average size of ∼50 nm was duplicated from the graphene oxide paper, which displayed a layer-by-layer structure on the microscale. The papers composed of nanosheets had an average pore size of ∼10 nm. Moreover, the as-prepared CuO-ZnO papers displayed high hybridization on the nanoscale. More importantly, the thickness of the single-layer CuO/ZnO nanosheet was about 2 nm (3-4 layer atom thickness). The as-synthesized nano-hybrid material with a high specific surface area and conjunct bimodal pores could play key roles for providing a shorter diffusion path and rapid electrolyte transport, which could further facilitate electrochemical reactions by providing more active sites. As an electrode material, it displayed high performances as a non-enzymatic sensor for the detection of glucose with a low potential (0.3 V vs. SCE), high sensitivity (3.85 mA mM-1 cm-2), wide linear range (5 μM to 3.325 mM), and low detection limit of 0.5 μM.

Micro/Nano robots have shown enormous potential for diverse biomedical applications, such as targeted delivery, in vivo biosensing, minimally invasive surgery andcell manipulation through extending their area of operation to various previously inaccessible locations. The motion of these small-scale robots can be eitherself–propelled or remotely controlled by some external power sources. However, in order to use them for biomedical applications, optimization of biocompatiblepropulsion and precise controllability are highly desirable. In this article, the recent progress about the biocompatible propulsion (e.g. self-propulsion, externalstimuli based propulsion and bio-hybrid propulsion) techniques for these micro/nano robotic devices are summarized along with their applications, with a specialfocus on the advantages and disadvantages of different propulsion techniques. The current challenges and future perspectives of these small-scale devices arediscussed in thefinal section.

Application of enzymatic biofuel cells (EBFCs) in wearable or implantable biomedical devices requires flexible and biocompatible electrode materials. To this end, freestanding and low-cost graphene paper is emerging among the most promising support materials. In this work, we have exploited the potential of using graphene paper with two-dimensional active surface (2D-GP) as carriers for enzyme immobilization to fabricate EBFCs, which represents the first case of flexible graphene papers directly used in EBFCs. The 2D-GP electrodes were prepared via the assembly of graphene oxide (GO) nanosheets into paper-like architecture, followed by reduction to form layered and cross-linked networks with good mechanical strength, high conductivity and little dependent on the degree of mechanical bending. 2D-GP electrodes served as both a current collector and an enzyme loading substrate that can be used directly as bioanode and biocathode. Pyrroloquinoline quinone dependent glucose dehydrogenase (PQQ-GDH) and bilirubin oxidase (BOx) adsorbed on the 2DGP electrodes both retain their biocatalytic activities. Electron transfer (ET) at the bioanode required Meldola blue (MB) as an ET mediator to shuttle electrons between PQQ-GDH and electrode, but direct electron transfer (DET) at the biocathode was achieved. The resulting glucose/oxygen EBFC displayed a notable mechanical flexibility, with wide open circuit voltage up to 0.665 V and maximum power density of approximately 4 µW/cm2 both fully competitive with reported values for related EBFCs, and with the mechanical flexibility and facile enzyme immobilization as novel merits.