Development of novel iron(III) crosslinked bioinks comprising carboxymethyl cellulose, xanthan gum, and hyaluronic acid for soft tissue engineering applications.

The advent of three-dimensional (3D) bioprinting offers a feasible approach to construct complex structures for soft tissue regeneration. Carboxymethyl cellulose (CMC) has been emerging as a very promising biomaterial for 3D bioprinting. However, due to the inability to maintain the post-printed stability, CMC needs to be physically blended and/or chemically crosslinked with other polymers. In this context, this study presents the combination of CMC with xanthan gum (XG) and hyaluronic acid (HA) to formulate a multicomponent bioink, leveraging the printability of CMC and XG, as well as the cellular support properties of HA. The ionic crosslinking of printed constructs with iron(III) via the metal-ion coordination between ferric cations and carboxylate groups of the three polymers was introduced to induce improved mechanical strength and long-term stability. Moreover, immortalized human epidermal keratinocytes (HaCaT) and human foreskin fibroblasts (HFF) encapsulated within iron-crosslinked printed hydrogels exhibited excellent cell viability (more than 95%) and preserved morphology. Overall, the presented study highlights that the combination of these three biopolymers and the ionic crosslinking with ferric ions is a valuable strategy to be considered for the development of new and advanced hydrogel-based bioinks for soft tissue engineering applications.

Graphene and metal-organic framework hybrids for high-performance sensors for lung cancer biomarker detection supported by machine learning augmentation.

Conventional diagnostic methods for lung cancer, based on breath analysis using gas chromatography and mass spectrometry, have limitations for fast screening due to their limited availability, operational complexity, and high cost. As potential replacement, among several low-cost and portable methods, chemoresistive sensors for the detection of volatile organic compounds (VOCs) that represent biomarkers of lung cancer were explored as promising solutions, which unfortunately still face challenges. To address the key problems of these sensors, such as low sensitivity, high response time, and poor selectivity, this study presents the design of new chemoresistive sensors based on hybridised porous zeolitic imidazolate (ZIF-8) based metal-organic frameworks (MOFs) and laser-scribed graphene (LSG) structures, inspired by the architecture of the human lung. The sensing performance of the fabricated ZIF-8@LSG hybrid sensors was characterised using four dominant VOC biomarkers, including acetone, ethanol, methanol, and formaldehyde, which are identified as metabolomic signatures in lung cancer patients' exhaled breath. The results using simulated breath samples showed that the sensors exhibited excellent performance for a set of these biomarkers, including fast response (2-3 seconds), a wide detection range (0.8 ppm to 50 ppm), a low detection limit (0.8 ppm), and high selectivity, all obtained at room temperature. Intelligent machine learning (ML) recognition using the multilayer perceptron (MLP)-based classification algorithm was further employed to enhance the capability of these sensors, achieving an exceptional accuracy (approximately 96.5%) for the four targeted VOCs over the tested range (0.8-10 ppm). The developed hybridised nanomaterials, combined with the ML methodology, showcase robust identification of lung cancer biomarkers in simulated breath samples containing multiple biomarkers and a promising solution for their further improvements toward practical applications.

Decoding the puzzle: recent breakthroughs in understanding degradation mechanisms of Li-ion batteries.

Lithium-ion batteries (LIBs) remain at the forefront of energy research due to their capability to deliver high energy density. Understanding their degradation mechanism has been essential due to their rapid engagement in modern electric vehicles (EVs), where battery failure may incur huge losses to human life and property. The literature on this intimidating issue is rapidly growing and often very complex. This review strives to succinctly present current knowledge contributing to a more comprehensible understanding of the degradation mechanism. First, this review explains the fundamentals of LIBs and various degradation mechanisms. Then, the degradation mechanism of novel Li-rich cathodes, advanced characterization techniques for identifying it, and various theoretical models are presented and discussed. We emphasize that the degradation process is not only tied to the charge-discharge cycles; synthesis-induced stress also plays a vital role in catalyzing the degradation. Finally, we propose further studies on advanced battery materials that can potentially replace the layered cathodes.

Utilising problematic waste to detect toxic gas release in the environment: fabricating a NiO doped CuO nanoflake based ammonia sensor from e-waste.

Using problematic electronic waste to synthesise high-purity nanomaterials can enable sustainable production and create opportunities to divert waste from landfills. Reported here is a simple strategy for the controllable synthesis of in situ NiO doped CuO nanoflakes from waste flexible printed circuit boards (FPCBs) using a chemothermal microrecycling process, and the nanomaterial is then utilised for an ammonia (NH3) sensor at room temperature. Characterisation of the nanoflakes confirmed the purity of the CuO phase with a monoclinic structure without the formation of the Cu2O phase. The NiO doped CuO 2D nanoflakes made of an assembly of 1D nanorods with a high surface area of 115.703 m2 g-1 are selectively synthesised from the waste FPCBs and have outstanding gas sensing characteristics such as a high response, a fast response (11.7 s) and a recovery time of (21.5 s), good stability, and superior selectivity towards 200 ppm of NH3 gas at room temperature (RT, 20 °C). From a broader perspective, the process opens up exciting new avenues explore the production of toxic gas sensing functional materials from toxic and problematic waste.

Fractal Design for Advancing the Performance of Chemoresistive Sensors.

The rapid advancement of internet of things (IoT)-enabled applications along with connected automation in sensing technologies is the heart of future intelligent systems. The probable applications have significant implications, from chemical process monitoring to agriculture, mining, space, wearable electronics, industrial manufacturing, smart cities, and point-of-care (PoC) diagnostics. Advancing sensor performance such as sensitivity to detect trace amounts (ppb-ppm) of analytes (gas/VOCs), selectivity, portability, and low cost is critical for many of these applications. These advancements are mainly achieved by selecting and optimizing sensing materials by their surface functionalization and/or structural optimization to achieve favorable transport characteristics or chemical binding/reaction sites. Surprisingly, the sensor geometry, shapes, and patterns were not considered as critical parameters, and most of these sensors were designed by following simple planar and interdigitated electrode geometry. In this study, we introduce a new bioinspired fractal approach to design chemoresistive sensors with fractal geometry, which grasp the architecture of fern leaves represented by the geometric group of space-filling curves of fractal patterns. These fractal sensors were printed by an extrusion process on a flexible substrate (PET) using specially formulated graphene ink as a sensing material, which provided significant enhancement of the active surface area to volume ratio and allowed high-resolution fractal patterning along with a reduced current transportation path. To demonstrate the advantages and influence of fractal geometry on sensor performance, here, three different kinds of sensors were fabricated based on different fractal geometrics (Sierpinski, Peano, and Hilbert), and the sensing performance was explored toward different VOC analytes (e.g., ethanol, methanol, and acetone). Among all these fractal-designed sensors including interdigitate sensors, the Hilbert-designed printed sensor shows enhanced sensing properties in terms of fast response time (6 s for 30 ppm), response value (14%), enhanced detection range (5-100 ppm), high selectivity, and low interference to humidity (up to RH 80%) for ethanol at room temperature (20 °C). Moreover, a significant improvement of this sensor performance was observed by applying the mechanical deformation (positive bending) technique. The practical application of this sensor was successfully demonstrated by monitoring food spoilage using a commercial box of strawberries as a model. Based on these presented results, this biofractal biomimetic VOC sensor is demonstrated for a prospective application in food monitoring.

Converging 2D Nanomaterials and 3D Bioprinting Technology: State-of-the-Art, Challenges, and Potential Outlook in Biomedical Applications.

The development of next-generation of bioinks aims to fabricate anatomical size 3D scaffold with high printability and biocompatibility. Along with the progress in 3D bioprinting, 2D nanomaterials (2D NMs) prove to be emerging frontiers in the development of advanced materials owing to their extraordinary properties. Harnessing the properties of 2D NMs in 3D bioprinting technologies can revolutionize the development of bioinks by endowing new functionalities to the current bioinks. First the main contributions of 2D NMS in 3D bioprinting technologies are categorized here into six main classes: 1) reinforcement effect, 2) delivery of bioactive molecules, 3) improved electrical conductivity, 4) enhanced tissue formation, 5) photothermal effect, 6) and stronger antibacterial properties. Next, the recent advances in the use of each certain 2D NMs (1) graphene, 2) nanosilicate, 3) black phosphorus, 4) MXene, 5) transition metal dichalcogenides, 6) hexagonal boron nitride, and 7) metal-organic frameworks) in 3D bioprinting technology are critically summarized and evaluated thoroughly. Third, the role of physicochemical properties of 2D NMSs on their cytotoxicity is uncovered, with several representative examples of each studied 2D NMs. Finally, current challenges, opportunities, and outlook for the development of nanocomposite bioinks are discussed thoroughly.

Microrecycled zinc oxide nanoparticles (ZnO NP) recovered from spent Zn-C batteries for VOC detection using ZnO sensor.

Non-intrusive techniques for diagnosis and biomonitoring - for example, breath testing to detect biomarkers - have the potential to support the advancement of versatile and remote point-of-care (PoC) diagnostics. This paper investigates tuning the sensitivity and selectivity performance of chemo-resistive sensors to detect volatile organic compound (VOC) biomarkers using a hybridized material of pristine graphene (pG) and zinc oxide nanoparticles (ZnO NP) recovered from spent Zn-C batteries. This hybridized graphene nanocomposite material of ZnO nanoparticles showed enhanced sensing performance because of high conductive property of graphene along with the synergetic interplay between graphene composite materials and ZnO NPs. The elevated surface area as well as adsorption capability of ZnO NPs provided improved sensitivity and selectivity for particular VOCs. It was proposed that this hybridized material could be used to fabricate chemo-resistive sensors with sensing performances tailored for VOC biomarker detection. To test this hypothesis, the ability of graphene hybrid nanocomposites with ZnO NPs to improve the sensing characteristics and efficiency of distinguishing diverse VOC biomarkers such as ethanol, acetone, methanol, chloroform, acetonitrile and terahydrofuran (THF) was investigated. Results demonstrated that the microrecycled ZnO based hybrid sensor has good selectivity along with the sensitivity towards ethanol and chloroform VOCs at room temperature (20 °C).

3D bioprinting of a cell-laden antibacterial polysaccharide hydrogel composite.

Bioink with inherent antibacterial activity is of particular interest for tissue engineering application due to the growing number of bacterial infections associated with impaired wound healing or bone implants. However, the development of cell-laden bioink with potent antibacterial activity while supporting tissue regeneration proved to be challenging. Here, we introduced a cell-laden antibacterial bioink based on Methylcellulose/Alginate (MC/Alg) hydrogel for skin tissue engineering via elimination of the risks associated with a bacterial infection. The key feature of the bioink is the use of gallium (Ga+3) in the design of bioink formulation with dual functions. First, Ga+3 stabilized the hydrogel bioink by the formation of ionic crosslinking with Alg chains. Second, the gallium-crosslinked bioink exhibited potent antibacterial activity toward both Gram-positive (Staphylococcus aureus) and Gram-negative (Pseudomonas aeruginosa) bacteria with a bactericidal rate of 99.99 %. In addition, it was found that the developed bioink supported encapsulated fibroblast cellular functions.

Graphene ink for 3D extrusion micro printing of chemo-resistive sensing devices for volatile organic compound detection.

Printed electronic sensors offer a breakthrough in the availability of low-cost sensor devices for improving the quality of human life. Conductive ink is the core of printing technology and also one of the fastest growing sector among all ink industries. Among many developed conductive inks, graphene-based inks are especially recognized as very promising for future fabrication of devices due to their low cost, unique properties, and compatibility with various platforms such as plastics, textiles, and paper. The development of graphene ink formulations for achieving high conductivity and high resolution printing is highly realized in 2D inkjet printing. Unfortunately, the ongoing development of graphene inks is possibly hampered by the non-uniform particle size and structures (e.g., different shapes and number of layers), which adversely affect printing resolution, conductivity, adhesion, and structural integrity. This study presents an environmentally sustainable route to produce graphene inks specifically designed for 3D extrusion-printing. The application of the prepared ink is demonstrated by mask-free automatic patterning of sensing devices for the detection of volatile organic compounds (VOCs). The sensing devices fabricated with this new ink display high-resolution patterning (average height/thickness of ∼12 µm) and a 10-fold improvement in the surface area/volume (SA/V) ratio compared to a conventional drop casting method. The extrusion printed sensors show enhanced sensing characteristics in terms of sensitivity and selectivity towards trace amount of VOC (e.g. 5 ppm ethanol) at room temperature (20 °C), which highlights that our method has highly promising potential in graphene printing technology for sensing applications.

Fast response hydrogen gas sensor based on Pd/Cr nanogaps fabricated by a single-step bending deformation.

The development of low-cost and high performing hydrogen gas sensors is important across many sectors, including mining, energy and defense using hydrogen (H2) gas. Herein, we demonstrate a new concept of H2 sensors based on Pd/Cr nanogaps created by using a simple mechanical bending deformation technique. These nanogap sensors can selectively detect the H2 gas based on transduction of the volume expansion after H2 uptake into an electrical signal by palladium-based metal-hydrides that allows closure of nanogaps for electrons flowing or tunneling. While this break-junction architecture, according to literature, can provide several advantages with research gaps in terms of fabricating nanogap sensors with ultra-fast response (≤4 s), the size of nanogap (≤20 nm) and their relationship with time response and recovery as addressed in this paper. Based on the computational modelling outcome, the size of the nanogaps can be investigated in order to optimize the fabrication conditions. Indeed, a single nanogap with optimum width (15 nm) acts as an on-off switch for best performing hydrogen detection. Moreover, with the unique design of Pd/Cr nanogap, the developed sensing device meets major requirement of advanced H2 gas sensor including room temperature (25 °C) operation, detection of trace amounts (10-40,000 ppm), good linearity, ultra-fast response-recovery time (3/4.5 s) and high selectivity. The presented economical lithography-free fabrication method has simple circuitry, low power consumption, recyclability, and favorable aging properties that promises great potential to be used for many practical applications of H2 detection.

Functional inks and extrusion-based 3D printing of 2D materials: a review of current research and applications.

Graphene and related 2D materials offer an ideal platform for next generation disruptive technologies and in particular the potential to produce printed electronic devices with low cost and high throughput. Interest in the use of 2D materials to create functional inks has exponentially increased in recent years with the development of new ink formulations linked with effective printing techniques, including screen, gravure, inkjet and extrusion-based printing towards low-cost device manufacturing. Exfoliated, solution-processed 2D materials formulated into inks permits additive patterning onto both rigid and conformable substrates for printed device design with high-speed, large-scale and cost-effective manufacturing. Each printing technique has some sort of clear advantages over others that requires characteristic ink formulations according to their individual operational principles. Among them, the extrusion-based 3D printing technique has attracted heightened interest due to its ability to create three-dimensional (3D) architectures with increased surface area facilitating the design of a new generation of 3D devices suitable for a wide variety of applications. There still remain several challenges in the development of 2D material ink technologies for extrusion printing which must be resolved prior to their translation into large-scale device production. This comprehensive review presents the current progress on ink formulations with 2D materials and their broad practical applications for printed energy storage devices and sensors. Finally, an outline of the challenges and outlook for extrusion-based 3D printing inks and their place in the future printed devices ecosystem is presented.

3D bioprinting of cell-laden electroconductive MXene nanocomposite bioinks.

MXenes, a new family of burgeoning two-dimensional (2D) transition metal carbides/nitrides, have been extensively explored in recent years owing to their outstanding properties such as a large specific surface area, high electrical conductivity, low toxicity, and biodegradability. Numerous efforts have been devoted to exploring MXenes for various biomedical applications such as cancer therapy, bioimaging, biosensing, and drug delivery. However, the potential application of MXene nanosheets in tissue engineering has been almost overlooked despite their excellent performance in other biomedical applications. The overarching goal of this paper is to demonstrate the potential of MXene cell-laden bioinks for tissue engineering and their ability to assemble functional scaffolds to regenerate damaged tissue via 3D bioprinting. We formulate a new electroconductive cell-laden bioink composed of Ti3C2 MXene nanosheets dispersed homogeneously within hyaluronic acid/alginate (HA/Alg) hydrogels and showed its performance for extrusion-based 3D bioprinting. The prepared hydrogel bioinks with MXenes display excellent rheological properties, which allows the fabrication of multilayered 3D structures with high resolution and shape retention. Moreover, the introduction of Ti3C2 MXene nanosheets within the HA/Alg hydrogel introduces electrical conductivity to the ink, addressing the poor electrical conductivity of the current bioinks that mismatch with the physico-chemical properties of tissue. In addition, the MXene nanocomposite ink with encapsulated Human Embryonic Kidney 293 (HEK-293) cells displayed high cell viability (>95%) in both bulk hydrogel and 3D bioprinted structures. These results suggest that MXene nanocomposite bioinks and their 3D bioprinting with high electrical conductivity, biocompatibility and degradability can synergize some new applications for tissue and neural engineering.

3D printing of cell-laden electroconductive bioinks for tissue engineering applications.

Bioprinting is an emerging powerful fabrication method, which enables the rapid assembly of 3D bioconstructs with dispensing cell-laden bioinks in pre-designed locations. However, to translate this technology into real applications, there are still a number of challenges that need to be addressed. First, the current inks are generally composed of polymeric materials with poor electrical conductivity that mismatches with the native tissue environment. The second challenge associated with the 3D bioprinting of hydrogel-based bioinks is the fabrication of anatomical-size constructs without any loss of shape fidelity and resolution. To address these challenges, in this work, we introduced a biocompatible bioink associated with current 3D bioprinting by combining methylcellulose and kappa-carrageenan (MC/κCA) hydrogels with poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) conducting polymers. The prepared ink exhibited highly thixotropic behaviour, which could be tuned via changing the concentration of MC and κCA to obtain easy printing with high shape fidelity. The ink was able to fabricate physiological-scale constructs without requiring a secondary support bath. In addition, varying the concentration of PEDOT:PSS could control the electrical conductivity of the ink. Moreover, the encapsulated human embryonic kidney 293 (HEK-293) cells in bulk hydrogels and 3D bioprinted structures maintained high cell viability (>96%) over a week, confirming the in vitro biocompatibility of the ink. Overall, these findings indicate that the MC/κCA/PEDOT:PSS bioink can be promising in biomedical applications, which improved the electroconductivity of bioinks and can exploit the advantage of conductive polymers in the 3D bioprinting technology.

Plant ontogeny determines strength and associated plant fitness consequences of plant-mediated interactions between herbivores and flower visitors.

Plants show ontogenetic variation in growth-defence strategies to maximize reproductive output within a community context. Most work on plant ontogenetic variation in growth-defence trade-offs has focussed on interactions with antagonistic insect herbivores. Plants respond to herbivore attack with phenotypic changes. Despite the knowledge that plant responses to herbivory affect plant mutualistic interactions with pollinators required for reproduction, indirect interactions between herbivores and pollinators have not been included in the evaluation of how ontogenetic growth-defence trajectories affect plant fitness.In a common garden experiment with the annual Brassica nigra, we investigated whether exposure to various herbivore species on different plant ontogenetic stages (vegetative, bud or flowering stage) affects plant flowering traits, interactions with flower visitors and results in fitness consequences for the plant.Effects of herbivory on flowering plant traits and interactions with flower visitors depended on plant ontogeny. Plant exposure in the vegetative stage to the caterpillar Pieris brassicae and aphid Brevicoryne brassicae led to reduced flowering time and flower production, and resulted in reduced pollinator attraction, pollen beetle colonization, total seed production and seed weight. When plants had buds, infestation by most herbivore species tested reduced flower production and pollen beetle colonization. Pollinator attraction was either increased or reduced. Plants infested in the flowering stage with P. brassicae or Lipaphis erysimi flowered longer, while infestation by any of the herbivore species tested increased the number of flower visits by pollinators.Our results show that the outcome of herbivore-flower visitor interactions in B. nigra is specific for the combination of herbivore species and plant ontogenetic stage. Consequences of herbivory for flowering traits and reproductive output were strongest when plants were attacked early in life. Such differences in selection pressures imposed by herbivores to specific plant ontogenetic stages may drive the evolution of distinct ontogenetic trajectories in growth-defence-reproduction strategies and include indirect interactions between herbivores and flower visitors. Synthesis. Plant ontogeny can define the direct and indirect consequences of herbivory. Our study shows that the ontogenetic stage of plant individuals determined the effects of herbivory on plant flowering traits, interactions with flower visitors and plant fitness.

Manganese oxide synthesized from spent Zn-C battery for supercapacitor electrode application.

Manganese oxide (Mn3O4) nanomaterials have promising potential to be used as supercapacitor electrode materials due to its high energy storage performance and environmental compatibility. Besides, every year huge volume of waste batteries including Zn-C battery ends up in landfill, which aggravates the burden of waste disposal in landfill and creates environmental and health threat. Thus, transformation of waste battery back into energy application, is of great significance for sustainable strategies. Compared with complex chemical routes which mostly apply toxic acids to recover materials from Zn-C battery, this study establishes the recovery of Mn3O4 particles via thermal route within 900 °C under controlled atmosphere. Synthesized Mn3O4 were confirmed by XRD, EDS, FTIR, XPS and Raman analysis and FESEM micrographs confirmed the coexistence of spherical and cubic Mn3O4 particles. Mn3O4 electrode derived from waste Zn-C battery demonstrate compatible electrochemical performance with standard materials and conventional synthesis techniques. Mn3O4 electrode exhibited highest capacitance value of 125 Fg-1 at 5 mVs-1 scan rate. The stability of the electrode showed good retention in discharge and charge capacity by about 80% after 2100 cycles. This study demonstrates that waste Zn-C battery can be further utilized for energy storage application, providing sustainable and economic benefits.

Selective synthesis of CuNi alloys using waste PCB and NiMH battery.

The aim of this study is to establish the potential novel approach for the selective synthesis of copper-nickel (CuNi) alloys using two waste streams, printed circuit board (PCB) and nickel-metal hydride (NiMH) batteries. A thermal route is established to synthesise CuNi alloys by using waste PCB, simultaneously as a Cu source and reducing agent from C-bearing polymer and waste NiMH batteries as Ni source. Thermal transformation and reduction studies were carried out at 1500 °C under an inert atmosphere. Initial characterization of raw materials was conducted in detail using various analytical techniques. Synthesised CuNi alloys were confirmed with ICP, EDS and XRD analyses. Material ratios of 75-25 wt% and 50-50 wt% of NiMH battery and PCB waste was considered and these range of compositions of e-waste, as raw materials, minimised the slag generation and optimised Ni recovery. Concentration of Nickel in the synthesised alloys was 20-30 wt%. Reduction extent of nickel oxide using PCB as reductant was confirmed by off-gas analysis. This approach has the potential to be implemented in selective synthesis of CuNi alloys instead of using conventional ores/reductant, to achieve target composition of alloys as per application requirements including marine/automotive/electronic industries. This novel approach promises significant benefits to divert e-wastes from landfill and provide sustainable solution for future metal alloy security.

Zinc Oxide Nanoparticles from Waste Zn-C Battery via Thermal Route: Characterization and Properties.

Disposable batteries are becoming the primary sources of powering day-to-day gadgets and consequently contributing to e-waste generation. The emerging e-waste worldwide is creating concern regarding environmental and health issues. Therefore, a sustainable recycling approach of spent batteries has become a critical focus. This study reports the detail characterization and properties of ZnO nanoparticles recovered from spent Zn-C batteries via a facile thermal synthesis route. ZnO nanoparticles are used in many applications including energy storage, gas sensors, optoelectronics, etc. due to the exceptional physical and optical properties. A thermal treatment at 900 °C under an inert atmosphere of argon was applied to synthesize ZnO nanoparticles from a spent Zn-C battery using a horizontal quartz tube furnace. X-ray diffraction (XRD), selected area electron diffraction (SAED) and X-ray photoelectron spectroscopy (XPS) results confirmed the formation of crystalline ZnO nanoparticles. Field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) analysis confirmed that the size of synthesised ZnO particles were less than 50 nm and mainly composed of sphere shaped nanoparticles. Synthesized ZnO exhibited BET surface area of 9.2629 m²/g and showed absorption of light in the UV region. Excitation of ZnO by UV light showed photoluminescence in the visible range. This study will create an opportunity for potential applications of ZnO nanoparticles from spent batteries and will benefit the environment by reducing the volume of e-waste in landfills.