Addressing preliminary challenges in upscaling the recovery of lithium from spent lithium ion batteries by the electrochemical method: a review

The paramount importance of lithium (Li) nowadays and the mounting volume of untreated spent LIB have imposed pressure on innovators to tackle the near-term issue of Li resource depletion through recycling. The trajectory of research dedicated to recycling has skyrocketed in this decade, reflecting the global commitment to addressing the issues surrounding Li resources. Although metallurgical methods, such as pyro- and hydrometallurgy, are presently prevalent in Li recycling, they exhibit unsustainable operational characteristics including elevated temperatures, the utilization of substantial quantities of expensive chemicals, and the generation of emissions containing toxic gases such as Cl2, SO2, and NOx. Therefore, the alternative electrochemical method has gained growing attention, as it involves a more straightforward operation leveraging ion-selective features and employing water as the main reagent, which is seen as more environmentally benign. Despite this, intensive efforts are still required to advance the electrochemical method toward commercialisation. This review highlights the key points in the electrochemical method that demand attention, including the feasibility of a large-scale setup, consideration of the substantial volume of electrolyte consumption, the design of membranes with the desired features, a suitable layout of the membrane, and the absence of techno-economic assessments for the electrochemical method. The perspectives presented herein provide a crucial understanding of the challenges of advancing the technological readiness level of the electrochemical method.

Engineered liposomes mediated approach for targeted colorectal cancer drug Delivery: A review

Colorectal cancer (CRC) continues to be one of the most prevalent and deadliest forms of cancer worldwide, despite notable advancements in its management. The prognosis for metastatic CRC remains discouraging, with a relative 5-year survival rate for stage IV CRC patients. Conventional treatments for advanced malignancies such as chemotherapy, often face limitations in effectively targeting cancer cells resulting in off-target distribution and significant side effects. In the quest for better strategies, researchers have explored numerous alternatives. Among these, nanoparticles (NPs) specifically liposomes have emerged as one of the most promising candidates in developing targeted delivery systems for cancer therapeutics. This review discusses the current approaches employing functionalised liposomes to overcome major biological barriers in therapeutics delivery for CRC treatment. We have also shared our perspectives on the technological development of liposomes for future clinical use and highlighted a few useful insights on the material choices for future research work in CRC.

Electroreduction of dissolved carbon dioxide on roughened molybdenum microelectrodes

The increasing levels of carbon dioxide (CO2) in the atmosphere may dissolve into the ocean and affect the marine ecosystem. It is crucial to determine the level of dissolved CO2 in the ocean to enable suitable mitigation actions to be carried out. The conventional electrode materials are expensive and susceptible to chloride ion attack. Therefore, there is a need to find suitable alternative materials. This novel study investigates the electrochemical behaviour of dissolved CO2 on roughened molybdenum (Mo) microdisk electrodes, which were mechanically polished using silicon carbide paper. Pits and dents can be seen on the electrode surface as observed using scanning electron microscopy. X-ray diffraction spectra confirm the absence of abrasive materials and the presence of defects on the electrode surface. The electrochemical surface for the roughened electrodes is higher than that for the smoothened electrodes. Our findings show that the roughened electrodes exhibit a significantly higher electrocatalytic activity than the smoothened electrodes for the reduction of dissolved CO2. Our results reveal a linear relationship between the current and square root of scan rate. Furthermore, we demonstrate that saturating the electrolyte solution with CO2 using a bubbling time of just 20 minutes at a flow rate of 5 L min-1 for a 50 mL solution is sufficient. This study provides new insights into the electrochemical behaviour of dissolved CO2 on roughened Mo microdisk electrodes and highlights their potential as a promising material for CO2 reduction and other electrochemical applications. Ultimately, our work contributes to the ongoing efforts to mitigate the effects of climate change and move towards a sustainable future.

Enhancing the Washing Durability and Electrical Longevity of Conductive Polyaniline-Grafted Polyester Fabrics

The demand for wearable electronics has driven the development of conductive fabrics, particularly those incorporating polyaniline (PANI) that is known for its high electrical conductivity, flexibility, and ease of fabrication. However, the limited stability and durability of the conductive fabric, especially during washing, present significant challenges. The drawbacks can be traced by weak physical attachment between the fabric and the conductive coating, leading to a decrease in conductivity over time. These drawbacks significantly impact the fabric's functionality and performance, highlighting the need for effective solutions to enhance its stability and durability. This study focuses on addressing these challenges by employing a thermochemical treatment. A hydrophilic surface of the polyester fabric is obtained after the treatment (hydrolysis), followed by grafting of PANI on it. The adhesion between PANI and the polyester fabrics was found to be enhanced, as proved by contact angle analysis. Furthermore, the PANI-hydrolyzed fabrics (treated) demonstrated stable conductivity (∼10-3 S cm-3) even after 10 washing cycles, showcasing their excellent durability. In comparison, the unhydrolyzed PANI fabric experienced a drop in conductivity by three orders of magnitude. X-ray photoelectron spectroscopy via N 1s core line spectra showed chemical shifts and quantified the level of doping through PANI's protonation level. We found that PANI-hydrolyzed fabrics preserved their dedoping level from 44.77 to 42.68%, indicating improved stability and extension of their electrical properties' lifetime after washing as compared to unhydrolyzed (untreated) fabrics, from 36.99 to 26.61%. This investigation demonstrates that the thermochemical approach can effectively enhance the durability of conductive PANI fabrics, enabling them to withstand the washing process while preserving their electrical endurance.

Application of Conductive Hydrogels on Spinal Cord Injury Repair: A Review

Spinal cord injury (SCI) causes severe motor or sensory damage that leads to long-term disabilities due to disruption of electrical conduction in neuronal pathways. Despite current clinical therapies being used to limit the propagation of cell or tissue damage, the need for neuroregenerative therapies remains. Conductive hydrogels have been considered a promising neuroregenerative therapy due to their ability to provide a pro-regenerative microenvironment and flexible structure, which conforms to a complex SCI lesion. Furthermore, their conductivity can be utilized for noninvasive electrical signaling in dictating neuronal cell behavior. However, the ability of hydrogels to guide directional axon growth to reach the distal end for complete nerve reconnection remains a critical challenge. In this Review, we highlight recent advances in conductive hydrogels, including the incorporation of conductive materials, fabrication techniques, and cross-linking interactions. We also discuss important characteristics for designing conductive hydrogels for directional growth and regenerative therapy. We propose insights into electrical conductivity properties in a hydrogel that could be implemented as guidance for directional cell growth for SCI applications. Specifically, we highlight the practical implications of recent findings in the field, including the potential for conductive hydrogels to be used in clinical applications. We conclude that conductive hydrogels are a promising neuroregenerative therapy for SCI and that further research is needed to optimize their design and application.

Mechanical and Structural Properties of Polyhydroxybutyrate as Additive in Blend Material in Additive Manufacturing for Medical Applications

Today, additive manufacturing (AM) is considered one of the vital tenets of the industry 4.0 revolution due to its high productivity, decentralized production and rapid prototyping. This work aims to study the mechanical and structural properties of polyhydroxybutyrate as an additive in blend materials and its potential in medical applications. PHB/PUA blend resins were formulated with 0 wt.%, 6 wt.%, 12 wt.% and 18 wt.% of PHB concentration. Stereolithography or an SLA 3D printing technique were used to evaluate the printability of the PHB/PUA blend resins. Additionally, from FESEM analysis, a change was observed in PUA's microstructure, with an additional number of voids spotted. Furthermore, from XRD analysis, as PHB concentration increased, the crystallinity index (CI) also increased. This indicates the brittleness properties of the materials, which correlated to the weak performance of the tensile and impact properties. Next, the effect of PHB loading concentration within PHB/PUA blends and aging duration towards the mechanical performance of tensile and impact properties was also studied by using analysis of variance (ANOVA) with a two-way method. Finally, 12 wt.% of PHB/PUA was selected to 3D print the finger splint due to its characteristics, which are compatible to be used in finger bone fracture recovery.

Revealing the improved sensitivity of PEDOT:PSS/PVA thin films through secondary doping and their strain sensors application

The field of strain sensing involves the ability to measure an electrical response that corresponds to a strain. The integration of synthetic and conducting polymers can create a flexible strain sensor with a wide range of applications, including soft robotics, sport performance monitoring, gaming and virtual reality, and healthcare and biomedical engineering. However, the use of insulating synthetic polymers can impede the semiconducting properties of sensors, which may reduce sensor sensitivity. Previous research has shown that the doping process can significantly enhance the electrical performance and ionic conduction of conducting polymers, thereby strengthening their potential for use in electronic devices. However the full effects of secondary doping on the crystallinity, stretchability, conductivity, and sensitivity of conducting polymer blends have not been studied. In this study, we investigated the effects of secondary doping on the properties of poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate)/poly(vinyl alcohol) (PEDOT:PSS/PVA) polymer blend thin films and their potential use as strain sensors. The thin films were prepared using a facile drop-casting method. Morphology analysis using profilometry and atomic force microscopy confirmed the occurrence of phase segregation and revealed surface roughness values. This evidence provided a comprehensive understanding of the chemical interactions and physical properties of the thin films, and the effects of doping on these properties. The best films were selected and applied as sensitive strain sensors. EG-PEDOT:PSS/PVA thin films showing a significant increase of conductivity values from the addition of 1 vol% to 12 vol% addition, with conductivity values of 8.51 × 10^-5 to 9.42 × 10^-3 S cm^-1. Our 12% EG-PEDOT:PSS/PVA sensors had the highest GF value of 2000 too. We compared our results with previous studies on polymeric sensors, and it was found that our sensors quantitatively had better GF values. Illustration that demonstrates the DMSO and EG dopant effects on PEDOT:PSS structure through bonding interaction, crystallinity, thermal stability, surface roughness, conductivity and stretchability was also provided. This study suggests a new aspect of doping interaction that can enhance the conductivity and sensitivity of PEDOT:PSS for device applications.

Fabrication Methods of Electroactive Scaffold-Based Conducting Polymers for Tissue Engineering Application: A Review

Conductive scaffolds, defined as scaffold systems capable of carrying electric current, have been extensively researched for tissue engineering applications. Conducting polymers (CPs) as components of conductive scaffolds was introduced to improve morphology or cell attachment, conductivity, tissue growth, and healing rate, all of which are beneficial for cardiac, muscle, nerve, and bone tissue management. Conductive scaffolds have become an alternative for tissue replacement, and repair, as well as to compensate for the global organ shortage for transplantation. Previous researchers have presented a wide range of fabrication methods for conductive scaffolds. This review highlights the most recent advances in developing conductive scaffolds, with the aim to trigger more theoretical and experimental work to address the challenges and prospects of these new fabrication techniques in medical sciences.

Synthesis, Characterisation and Antibacterial Properties of Silicone-Silver Thin Film for the Potential of Medical Device Applications

Silver (Ag) particles have sparked considerable interest in industry and academia, particularly for health and medical applications. Here, we present the “green” and simple synthesis of an Ag particle-based silicone (Si) thin film for medical device applications. Drop-casting and peel-off techniques were used to create an Si thin film containing 10–50% (v/v) of Ag particles. Electro impedance spectroscopy (EIS), X-ray diffraction analysis (XRD), scanning electron microscopy (SEM), energy dispersive X-ray (EDX), and tensile tests were used to demonstrate the electrical conductivity, crystallinity, morphology-elemental, and mechanical properties, respectively. The oriented crystalline structure and excellent electronic migration explained the highest conductivity value (1.40 × 10⁻⁵ S cm⁻¹) of the 50% Ag–Si thin film. The findings regarding the evolution of the conductive network were supported by the diameter and distribution of Ag particles in the Si film. However, the larger size of the Ag particles in the Si film resulted in a lower tensile stress of 68.23% and an elongation rate of 68.25% compared to the pristine Si film. The antibacterial activity of the Ag–Si film against methicillin-resistant Staphylococcus aureus (MRSA), Bacillus cereus (B. cereus), Klebsiella pneumoniae (K. pneumoniae), and Pseudomonas aeruginosa (P. aeruginosa) was investigated. These findings support Si–Ag thin films’ ability to avoid infection in any medical device application.

Advocating Electrically Conductive Scaffolds with Low Immunogenicity for Biomedical Applications: A Review

Scaffolds support and promote the formation of new functional tissues through cellular interactions with living cells. Various types of scaffolds have found their way into biomedical science, particularly in tissue engineering. Scaffolds with a superior tissue regenerative capacity must be biocompatible and biodegradable, and must possess excellent functionality and bioactivity. The different polymers that are used in fabricating scaffolds can influence these parameters. Polysaccharide-based polymers, such as collagen and chitosan, exhibit exceptional biocompatibility and biodegradability, while the degradability of synthetic polymers can be improved using chemical modifications. However, these modifications require multiple steps of chemical reactions to be carried out, which could potentially compromise the end product's biosafety. At present, conducting polymers, such as poly(3,4-ethylenedioxythiophene) poly(4-styrenesulfonate) (PEDOT: PSS), polyaniline, and polypyrrole, are often incorporated into matrix scaffolds to produce electrically conductive scaffold composites. However, this will reduce the biodegradability rate of scaffolds and, therefore, agitate their biocompatibility. This article discusses the current trends in fabricating electrically conductive scaffolds, and provides some insight regarding how their immunogenicity performance can be interlinked with their physical and biodegradability properties.

Investigating how amine structure influences drug-amine ion-pair formation and uptake via the polyamine transporter in A549 lung cells

Transiently associating amines with therapeutic agents through the formation of ion-pairs has been established both in vitro and in vivo as an effective means to systemically direct drug delivery to the lung via the polyamine transport system (PTS). However, there remains a need to better understand the structural traits required for effective PTS uptake of drug ion-pairs. This study aimed to use a structurally related series of amine counterions to investigate how they influenced the stability of theophylline ion-pairs and their active uptake in A549 cells. Using ethylamine (mono-amine), ethylenediamine (di-amine), spermidine (tri-amine) and spermine (tetra-amine) as counterions the ion-pair affinity was shown to increase as the number of protonated amine groups in the counterion structure increased. The mono and diamines generated a single hydrogen bond and the weakest ion-pair affinities (pK_FTIR: 1.32 ± 0.04 and 1.43 ± 0.02) whereas the polyamines produced two hydrogen bonds and thus the strongest ion-pair affinities (pK_FTIR: 1.93 ± 0.05 and 1.96 ± 0.04). In A549 cells depleted of endogenous polyamines using α-difluoromethylornithine (DFMO), the spermine-theophylline uptake was significantly increased (p < 0.05) compared to non-amine depleted cells and this evidenced the active PTS sequestering of the ion-pair. The mono-amine and di-amine failed to enhance theophylline uptake in these A549 cells, but the tri-amine and tetra-amine both almost doubled the theophylline uptake into the cells when compared to the uptake of free drug. As the data indicated that polyamines with at least 3 amines were required to form ion-pairs that could enhance A549 cell uptake, it suggested that at least two amines were required to physically stabilise the ion-pair and one to interact with the PTS.

Synthesis and Characterization of Porous, Electro-Conductive Chitosan-Gelatin-Agar-Based PEDOT: PSS Scaffolds for Potential Use in Tissue Engineering

Herein we report the synthesis and characterization of electro-conductive chitosan-gelatin-agar (Cs-Gel-Agar) based PEDOT: PSS hydrogels for tissue engineering. Cs-Gel-Agar porous hydrogels with 0-2.0% (v/v) PEDOT: PSS were fabricated using a thermal reverse casting method where low melting agarose served as the pore template. Sample characterizations were performed by means of scanning electron microscopy (SEM), attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR), X-ray diffraction analysis (XRD) and electrochemical impedance spectroscopy (EIS). Our results showed enhanced electrical conductivity of the cs-gel-agar hydrogels when mixed with DMSO-doped PEDOT: PSS wherein the optimum mixing ratio was observed at 1% (v/v) with a conductivity value of 3.35 × 10-4 S cm-1. However, increasing the PEDOT: PSS content up to 1.5 % (v/v) resulted in reduced conductivity to 3.28 × 10-4 S cm-1. We conducted in vitro stability tests on the porous hydrogels using phosphate-buffered saline (PBS) solution and investigated the hydrogels' performances through physical observations and ATR-FTIR characterization. The present study provides promising preliminary data on the potential use of Cs-Gel-Agar-based PEDOT: PSS hydrogel for tissue engineering, and these, hence, warrant further investigation to assess their capability as biocompatible scaffolds.

Stretchable AgX (X = Se, Te) for Efficient Thermoelectrics and Photovoltaics

Transition metal chalcogenides (TMCs) have gained worldwide interest owing to their outstanding renewable energy conversion capability. However, the poor mechanical flexibility of most existing TMCs limits their practical commercial applications. Herein, triggered by the recent and imperative synthesis of highly ductile α-Ag₂S, an effective approach based on evolutionary algorithm and ab initio total-energy calculations for determining stable, ductile phases of bulk and two-dimensional Ag_xSe_1-x and Ag_xTe_1-x compounds was implemented. The calculations correctly reproduced the global minimum bulk stoichiometric P2₁2₁2₁-Ag₈Se₄ and P2₁/c-Ag₈Te₄ structures. Recently reported metastable AgTe₃ was also revealed but it lacks dynamical stability. Further single-layered screening unveiled two new monolayer P4/nmm-Ag₄Se₂ and C2-Ag₈Te₄ phases. Orthorhombic Ag₈Se₄ crystalline has a narrow, direct band gap of 0.26 eV that increases to 2.68 eV when transforms to tetragonal Ag₄Se₂ monolayer. Interestingly, metallic P2₁/c-Ag₈Te₄ changes to semiconductor when thinned down to monolayer, exhibiting a band gap of 1.60 eV. Present findings confirm their strong stability from mechanical and thermodynamic aspects, with reasonable Vickers hardness, bone-like Young's modulus (E) and high machinability observed in bulk phases. Detailed analysis of the dielectric functions ε(ω), absorption coefficient α(ω), power conversion efficiency (PCE) and refractive index n(ω) of monolayers are reported for the first time. Fine theoretical PCE (SLME method ∼11-28%), relatively high n(0) (1.59-1.93), and sizable α(ω) (10⁴-10⁵ cm^-1) that spans the infrared to visible regions indicate their prospects in optoelectronics and photoluminescence applications. Effective strategies to improve the temperature dependent power factor (PF) and figure of merit (ZT) are illustrated, including optimizing the carrier concentration. With decreasing thickness, ZT of p-doped Ag-Se was found to rise from approximately 0.15-0.90 at 300 K, leading to a record high theoretical conversion efficiency of ∼12.0%. The results presented foreshadow their potential application in a hybrid device that combines the photovoltaic and thermoelectric technologies.

Potential Applications of Conducting Polymers to Reduce Secondary Bacterial Infections among COVID-19 Patients: a Review

The COVID-19 pandemic is a motivation for material scientists to search for functional materials with valuable properties to alleviate the risks associated with the coronavirus. The formulation of functional materials requires synergistic understanding on the properties of materials and mechanisms of virus transmission and disease progression, including secondary bacterial infections that are prevalent in COVID-19 patients. A viable candidate in the struggle against the pandemic is antimicrobial polymer, due to their favorable properties of flexibility, lightweight, and ease of synthesis. Polymers are the base material for personal protective equipment (PPE), such as gloves, face mask, face shield, and coverall suit for frontliners. Conducting polymers (CPs) are polymers with electrical properties due to the addition of dopant in the polymer structure. The conductivity of polymers augments their antiviral and antibacterial properties. This review discusses the types of CPs and how their properties could be exploited to ward off bacterial infections in hospital settings, specifically in cases involving COVID-19 patients. This review also covers common CPs fabrication techniques. The key components to produce CPs at several possibilities to fit the current needs in fighting secondary bacterial infections are also discussed.

Electrically Conductive Polyester Fabrics Embedded Polyaniline

Recently, conductive fabric has attracted massive attention among researchers due to their unique conductive properties with a wide range of possible applications. This study explores the fabrication of poly aniline (PANI) conductive fabric through an immersion technique of polyester fabric in PANI solution. Two types of acids (sulphuric acid (H2SO4) and p-toulene sulfonic acid (pTSA) have been employed as the doping agent to induce the conductivity in various weight percentages (0.3, 0.6 and 0.9 wt%) with immersion time of 5, 10 and 15 minutes. The fabricated conducting fabrics were then characterized by Fourier Transform Infrared Spectroscopy with attenuated total reflection (FTIR-ATR) and X-ray Diffraction (XRD) for analyses of chemical structure and phase identification respectively. Their morphologies were observed by Scanning Electron Microscope (SEM) which revealed the various fibrous structure. The finding is in line with the electrical conductivity properties of the fabrics observed using Four-point probe technique. Optimum conductivity of the conductive fabrics were found to be at 0.6 wt. % for both types of acid which are 1.30 x 10-2 S/cm (H2SO4) and 1.39 x10-3 S/cm (pTSA). Meanwhile, the varied immersion time showed no significant changes on this property, due to the short time laps. For FTIR results, the peaks confirmed the presence of PANI-EB together with the introduced acid within the PANI backbone. Collectively, H2SO4 is found to be a good candidate as doping agent, deduced from obtained conductivity values and structural properties.