Spatially Precise Genetic Engineering at the Electrode-Tissue Interface.

The interface between electrodes and neural tissues plays a pivotal role in determining the efficacy and fidelity of neural activity recording and modulation. While considerable efforts have been made to improve the electrode-tissue interface, the majority of studies have primarily concentrated on the development of biocompatible neural electrodes through abiotic materials and structural engineering. In this study, an approach is presented that seamlessly integrates abiotic and biotic engineering principles into the electrode-tissue interface. Specifically, ultraflexible neural electrodes with short hairpin RNAs (shRNAs) designed to silence the expression of endogenous genes within neural tissues are combined. The system facilitates shRNA-mediated knockdown of phosphatase and tensin homolog deleted on chromosome 10 (PTEN) and polypyrimidine tract-binding protein 1 (PTBP1), two essential genes associated in neural survival/growth and neurogenesis, within specific cell populations located at the electrode-tissue interface. Additionally, it is demonstrated that the downregulation of PTEN in neurons can result in an enlargement of neuronal cell bodies at the electrode-tissue interface. Furthermore, the system enables long-term monitoring of neuronal activities following PTEN knockdown in a mouse model of Parkinson's disease and traumatic brain injury. The system provides a versatile approach for genetically engineering the electrode-tissue interface with unparalleled precision, paving the way for the development of regenerative electronics and next-generation brain-machine interfaces.

Removal of Pb (II) and Zn (II) in the mineral beneficiation wastewater by using cross-linked carboxymethyl starch-g-methacrylic acid as an effective flocculant.

The cross-linked carboxymethyl starch-g-methacrylic acid (CCMS-g-MAA) was prepared by using grafting and micro-cross-linking in the one-pot preparation process. CCMS-g-MAA presented high removal capacity of Pb (II) of 57.13 mg/g at pH = 4 and high removal capacity of Zn (II) of 51.41 mg/g at pH = 5 by using a sample dosage of 0.68 g/L. Characterization results of FTIR, TG, and XRD illustrate that methacrylic acid and sodium tri-metaphosphate were successfully introduced into the structure of carboxymethyl starch. SEM characterization presented that the sample particles were amorphous aggregates with surface voids, which was favorable for the adsorption of heavy metal ions from wastewater. Adsorption isotherm results indicated that Freundlich equation could be better used to describe the adsorption process of metal ions on CCMS-g-MAA. The adsorption kinetic results indicated that the pseudo-second-order model is more suitable to describe this removal process. XPS results indicated that metal ions interacted with functional groups on the surface of flocculant, especially carboxyl groups. The removal process may be purposed that metal ions were adsorbed by porous material, and then combined with surface functional groups of the flocculant via electrostatic interaction, chelation or ion exchange. Subsequently, metal ions were separated from the wastewater with flocs precipitated in the bottom of solution via bridging and patching. The obtained results illustrated that CCMS-g-MAA was an effective material for the treatment of wastewater containing polymetallic ions besides mineral beneficiation wastewater supported by its excellent regeneration.

Ultraflexible Neural Probes for Multidirectional Neuronal Activity Recordings over Large Spatial and Temporal Scales.

The widespread dissemination of ultraflexible neural probes depends on the development of advanced materials and implementation strategies that can allow reliable implantation of ultraflexible neural probes into targeted brain regions, especially deep and difficult-to-access brain regions. Here, we report ultraflexible and multidirectional probes that are encapsulated in a biocompatible polymer alloy with controllable dissolution kinetics. Our probes can be reliably implanted into targeted brain regions over large spatial scales, including deep hindbrain regions that are anatomically difficult-to-access in vivo. Chronically implanted probes can enable long-term, multidirectional recordings from several hundreds of neurons across distributed brain regions. In particular, our results show that 87.0% of chronically recorded neurons in the hindbrain are interneurons, whereas only 41.9% of chronically recorded neurons in the cortex are interneurons. These results demonstrate that our ultraflexible neural probes are a promising tool for large-scale, long-term neural circuit dissection in the brain.

Synthesis of Castor Oil-Based Quaternary Ammonium Salt and Modification of Attapulgite for Treating Industrial Wastewaters.

In order to develop multifunctional quaternary ammonium salts and explore their advantages as modifiers for wastewater treatment, castor oil-based quaternary ammonium salts were synthesised and subsequently used as modifiers for attapulgite treatment. The structures of untreated and treated attapulgite were compared by Fourier transform infrared spectra and X-ray diffraction. The mechanism of modification was speculated. Various factors such as the amount of modified attapulgite, temperature and pH were also investigated in the batch experiments on the removal rates of acetone and phenol from wastewaters. The synthesis conditions were set as follows: the reaction temperature was 80 °C, the reaction time was 8 h, the molar ratio of castor oil to N,N-dimethyl-1,3-propanediamine was 1:5, the catalyst was 6% NaOH and the product yield was about 64.72%. The grafting rate of the castor oil-based quaternary ammonium salt was about 99.6% when the amount of modifier was 0.69 g per 5 g of attapulgite, the ultrasound treatment time was 11 min and the pH was 5. The quaternary ammonium salt was only associated with the surface of attapulgite and did not change the rod-like crystal structure of the silicate. The modified attapulgite is much more fibrous and exhibits a good distribution of crystal bundles. The removal rates were found to be less favourable under strongly acidic and strongly alkaline conditions. Under suitable conditions, for 50 mL industrial wastewaters (phenol: 100-160 mg/L; acetone: 680-800 mg/L), the amount of modified attapulgite was 1 g, the temperature was 80 °C and the pH was 7, and the maximum removal rates of acetone and phenol after 80 min reached about 65.71% and 78.72%, respectively, which were higher than those of ATP.

Self-assembled ultraflexible probes for long-term neural recordings and neuromodulation.

Ultraflexible microelectrode arrays (MEAs) that can stably record from a large number of neurons after their chronic implantation offer opportunities for understanding neural circuit mechanisms and developing next-generation brain-computer interfaces. The implementation of ultraflexible MEAs requires their reliable implantation into deep brain tissues in a minimally invasive manner, as well as their precise integration with optogenetic tools to enable the simultaneous recording of neural activity and neuromodulation. Here, we describe the process for the preparation of elastocapillary self-assembled ultraflexible MEAs, their use in combination with adeno-associated virus vectors carrying opsin genes and promoters to form an optrode probe and their in vivo experimental use in the brains of rodents, enabling electrophysiological recordings and optical modulation of neuronal activity over long periods of time (on the order of weeks to months). The procedures, including device fabrication, probe assembly and implantation, can be completed within 3 weeks. The protocol is intended to facilitate the applications of ultraflexible MEAs for long-term neuronal activity recording and combined electrophysiology and optogenetics. The protocol requires users with expertise in clean room facilities for the fabrication of ultraflexible MEAs.

Electrodeposited NaYF4:Yb3+, Er3+ up-conversion films for flexible neural device construction and near-infrared optogenetics.

Near-infrared optogenetics based on up-conversion materials provides a promising tool for the dissection of neural circuit functions in deep brain regions. However, it remains a challenge to combine near-infrared up-conversion optogenetic stimulation with high-density electrophysiological recording in a minimally invasive manner. Here, we develop a flexible device for simultaneous electrophysiological recording and near-infrared optogenetics. The flexible device is constructed by integrating polymer-based flexible recording microelectrodes with electrodeposited NaYF4:Yb3+, Er3+ up-conversion films that can convert deep-tissue-penetrating near-infrared light into visible light for optogenetic activation of C1V1-expressing neurons. The emission properties of the up-conversion films are optimized for green light emission to stimulate C1V1 opsins. Owing to their minimized surgical footprint and high mechanical compliance, chronically implanted devices enable simultaneous electrophysiological recording and near-infrared optogenetic modulation of neuronal activities in the brain.

Free-Standing Nanofilm Electrode Arrays for Long-Term Stable Neural Interfacings.

Flexible neural electrodes integrated on micrometer-thick polymer substrates offer important opportunities for improving the stability of neuronal activity recordings during cognitive processes. However, the bending stiffness of micrometer-thick polymer substrates is typically two orders of magnitude higher than that of nanofilm electrodes, making it a limiting factor in electrode-tissue interfacings. Here, this limitation is overcome by developing self-assembled nanofilm electrode arrays (NEAs) that consist of high-density, free-standing gold nanofilm electrodes. Chronically implanted NEAs can form intimate and innervated interfaces with neural tissue, enabling stable neuronal activity recordings across multiple brain regions over several months. As an application example, the activities of the same neuronal populations are tracked across odor discrimination reversal learning and it is illustrated how dorsal striatal neurons represent and update stimulus-outcome associations across multiple timescales. The results underscore the potential of free-standing nanoscale materials for interfacing biological systems over long terms.

Self-assembled multifunctional neural probes for precise integration of optogenetics and electrophysiology.

Optogenetics combined with electrical recording has emerged as a powerful tool for investigating causal relationships between neural circuit activity and function. However, the size of optogenetically manipulated tissue is typically 1-2 orders of magnitude larger than that can be electrically recorded, rendering difficulty for assigning functional roles of recorded neurons. Here we report a viral vector-delivery optrode (VVD-optrode) system for precise integration of optogenetics and electrophysiology in the brain. Our system consists of flexible microelectrode filaments and fiber optics that are simultaneously self-assembled in a nanoliter-scale, viral vector-delivery polymer carrier. The highly localized delivery and neuronal expression of opsin genes at microelectrode-tissue interfaces ensure high spatial congruence between optogenetically manipulated and electrically recorded neuronal populations. We demonstrate that this multifunctional system is capable of optogenetic manipulation and electrical recording of spatially defined neuronal populations for three months, allowing precise and long-term studies of neural circuit functions.

Gas Phase Dehydration of Glycerol to Acrolein Over Nickel Phosphate Catalysts.

We investigated the catalytic performance of glycerol conversion to acrolein on nickel phosphates samples (NiP-T (T = 300,400,500,600, and 700 °C)). The textural property, acidity of the fresh catalyst and carbon content of the used NiP-500 were also determined. The results showed that NiP was amorphous under the appropriate calcination temperature. The textural property, acid amount and strength were important in this reaction. Glycerol conversion was proportional to the acid amount of the sample. After 2 h on stream, NiP-500 with the largest pore size, largest acid amount and largest number of moderate acid sites had the maximum catalytic performance (89% glycerol conversion and 64% acrolein selectivity). NiP-700 showed the lowest performance (48% glycerol conversion and 34% acrolein selectivity), which is due to the lowest surface area, pore size and the lowest acid amount of NiP-700. Moreover, the catalyst deactivation was ascribed to carbon deposition on phosphates during the reaction.

Synthesis and Performance of a Novel High-Efficiency Coal Dust Suppressant Based on Self-Healing Gel.

During transportation and storage, coal produces a lot of dust, which pollutes the environment and threatens the occupational health of workers. Although many dust suppressants have been developed for dust prevention at work, the implementation of current dust suppressants does not meet the requirements due to various factors such as the hydrophobic nature of coal dust and a harsh external environment. In this study, hydroxyethyl cellulose, acrylamide, and stearyl methyl acrylate were used for micelle polymerization to prepare an environmental protection dust suppressant for preventing dust during coal storage and transportation. The microstructure of the reactants and the products was analyzed by Fourier transform infrared as well as scanning electron microscopy. The strength and self-healing tensile properties of binder coal were taken as indicators to determine the best synthesis dosage and conditions. The dust suppressant particles are applied to the dust accumulation area, contact each other after water absorption, and swell to complete the healing, to achieve the purpose of dust control. The evaluation of the relevant properties of the dust suppressant reveals that the dust suppressant has a good covering effect, an excellent dust suppressant performance, and a significant dust suppression action.

Vapour Phase Dehydration of Glycerol to Acrolein Over Wells-Dawson Type H6P2W18O62 Supported on Mesoporous Silica Catalysts Prepared by Supercritical Impregnation.

The H6P2W18O62/MCM-41-SUP was first synthesized using supercritical impregnation as highly efficient catalyst during glycerol conversion reaction. For comparison, the H6P2W18O62/MCM-41 prepared by conventional wet impregnation was also studied. The catalysts were studied using XRD, BET, FTIR, SEM, TEM, pyridine-FTIR, NH3-TPD, TG, ICP and elemental analysis. The characterization results showed that the preparation condition of supercritical carbon dioxide contributed to improve the dispersion of H6P2W18O62 on MCM-41, strengthen the interaction between H6P2W18O62 and MCM-41, increase the thermostability of H6P2W18O62 and enhance the amount of medium and Brønsted acid sites on the catalyst. Therefore, the formation of coke was retarded, and the lifetime of catalyst was prolonged. After 15 h reaction, the glycerol conversion rapidly reduced from 92% to 64% on H6P2W18O62/MCM-41-IMG (15.4 wt% coke), while the glycerol conversion slightly decreased from 94% to 82% on H6P2W18O62/MCM-41-SUP (9.8 wt% coke).