Atomic layer deposition: An efficient tool for corrosion protection

Atomic layer deposition (ALD) is now a widely implemented thin film growing method. It is currently used in industrial fabrication processes of microelectronics and luminescent display technologies. Since compact and conformal films can be grown with perfect control of the thickness, ALD is envisioned in numerous other applications fields such as energy, sensing, biomaterials, and photonics. Although few reports can be found on its application to corrosion protection, it has been shown that the qualities of ALD can be highly beneficial to this field. After a brief review of the principle of ALD and the effect of the main parameters on the properties of the films, this report attempts to show the interest of this technique to mitigate corrosion. Various examples of successful uses of ALD to protect metallic and non-metallic surfaces in different fields are reviewed.     

Additive manufacturing approaches for biological power generation

As the consequences of global warming continue to affect the climate, there is an increased need for technologies that decrease dependence on fossil fuel consumption and promote sustainability. Additive manufacturing (AM) not only enables the scale-up and mass production of renewable energy technologies but also reduces cost and lead time, minimizes waste, and uses less energy than traditional manufacturing processes. Moreover, AM brings design and innovation to the forefront by allowing for design strategy revision and rapid prototyping. Herein, AM approaches used to fabricate devices that enable biological power generation are described. Biological power generation is a process through which biocatalysts – electroactive bacteria, enzymes, or cyanobacteria – harvest electrons from chemical substrates or light. Device engineering directs electron transfer events to a conductive material and maximizes power output. This review covers recent AM approaches for biological power generation in the form of microbial fuel cells (MFCs), enzymatic fuel cells, and biophotovoltaic cells with an emphasis on MFCs. Fabrication methods and materials for electrodes, chambers, inserts, membranes, and biofilms are described, along with impacts on device performance.     

Investigation of infill-patterns on mechanical response of 3D printed poly-lactic-acid

This paper presents the effect of infill patterns (IPs) on the mechanical response of 3D printed specimens by conducting the low-velocity impact test (LVI) and compression test. The poly-lactic acid (PLA, purity 98 wt% >) material has selected and printed using fused deposition modeling (FDM, speed 20 mm/s, layer height 0.2 mm, no of layers 30, extruded at 200 °C) with four different IPs: triangle, grid, quarter cubic, and tri-hexagon. The LVI test on velocity-time, energy-time and force-displacement, and the compression responses have examined and presented in this study. The LVI test was carried out to determine the penetration energy level, energy absorption capacity (toughness), stiffness, and strength of PLA porous parts (60% infill density) for implant/tissue/recyclable product applications. The results have shown that the triangular pattern has produced the highest absorbed energy in LVI test (penetration energy 7.5 J, and stiffness 668.82 N/mm) due to more sheared/contact layers’ perpendicular to impactor (hemispherical insert); while the grid pattern exhibited the highest compressive strength (72 MPa) due to more layers aligned along the compressive loading direction The SEM fracture surface image of Triangular IP has produced effective raster and layer bonding, less number of voids, more amount of circular beach markings, and absence of ratchet lines leading to possess improved mechanical properties.     

Tuning of graphitic carbon nitride (g-C3N4) for photocatalysis: A critical review

Graphitic carbon nitride (g-C₃N₄) is a remarkable semiconductor catalyst that has attracted widespread attention as a visible light photo-responsive, metal-free, low-cost photocatalytic material. Pristine g-C₃N₄ suffers fast recombination of photogenerated electron-hole pairs, low surface area, and insufficient visible light absorption, resulting in low photocatalytic efficiency. This review presents the recent progress, perspectives, and persistent challenges in the development of g-C₃N₄-based photocatalytic materials. Several approaches employed to improve the visible light absorption of the materials including metal and non-metal doping, co-doping, and heterojunction engineering have been extensively discussed. These approaches, in general, were found to decrease the material’s bandgap, increase the surface area, reduce charge carrier recombination, and promote visible light absorption, thereby enhancing the overall photocatalytic performance. The material has been widely used for different applications such as photocatalytic hydrogen production, water splitting, CO₂ conversion, and water purification. The work has also identified various limitations and weaknesses associated with the material that hinders its maximum utilization under visible illumination and presented state-of-the-art solutions that have been reported recently. The summary presented in this review would add an invaluable contribution to photocatalysis research and facilitate the development of efficient visible light-responsive semiconducting materials.     

Formulation and molecular docking simulation study of luliconazole nanosuspension–based nanogel for transdermal drug delivery using modified polymer

The purpose of study was to formulate nanosuspension-based nanogel of luliconazole (LLZ) for transdermal delivery to enhance its skin retention and effectiveness using modified starch ester. Nanosuspensions show promising results with size of 369.1–745.4 nm having PDI 0.193–0.344 and zeta potential 22–45 mV. These nanosuspensions form micelles and hydrophobic core of it provides the reservoir for LLZ with better drug loading and binding interaction. Drug loading was confirmed by percent drug entrapment efficiency (PDEE) and PDI. Molecular docking simulation (MDS) provides detail insight of LLZ polymer complexation at hydrophobic cavity of micelles and revealed that there was binding between drug and polymer in aqueous milieu having interaction energy ranges from ?7.1 to ?6.0 kcal/mol. Nanosuspensions so made were incorporated into gel by using Carbopol 934 ® and tested for % drug content, spreadability, pH, and viscosity with ranges of 101.62–97.71, 28.94–34.38 (gcm/s), 6.91–7.21, and 4802.62–9461.83 (cp), respectively. Nanogel also evaluated for stability and skin permeation study using human cadaver skin (HCS). In vitro skin permeation study indicated that the amount of LLZ permeated through skin from nanogel (71.042–83.818 μgcm ?2) was higher than standard cream (70.085 μgcm ?2). Nanogel increased the accumulation of LLZ in HCS ~3 times than standard cream. The transdermal flux was greater for standard cream (123.79 μgcm ?2), whereas smaller for nanogel (50.394–82.743 μgcm ?2) due to skin retention. Nanosuspension-based gel are able to especially favor LLZ accumulation into skin, provide better drug loading, improve stability, and efficacy. Thus, targeting older antibiotics such as LLZ and formulating into nanosystem utilized to expand its usefulness to physicians to treat illnesses caused by resistant fungal strains.     

Recent studies on advance spectroscopic techniques for the identification of microorganisms: A review

The continuous development of resistance to antibiotic drugs by microorganisms causes high mortality and morbidity. Pathogens with distinct features and biochemical abilities make them destructive to human health. Therefore, early identification of the pathogen is of substantial importance for quick ailments and healthcare outcomes. Several phenotype methods are used for the identification and resistance determination but most of the conventional procedures are time-consuming, costly, and give qualitative results. Recently, great focus has been made on the utilization of advanced techniques for microbial identification. This review is focused on the research studies performed in the last five years for the identification of microorganisms particularly, bacteria using advanced spectroscopic techniques including mass spectrometry (MS), infrared (IR) spectroscopy, Raman spectroscopy (RS), and nuclear magnetic resonance (NMR) spectroscopy. Among all the techniques, MS techniques, particularly MALDI-TOF/MS have been widely utilized for microbial identification. A total of 44 bacteria i.e., 6 Staphylococcus spp., 3 Enterococcus spp., 6 Bacillus spp., 4 Streptococcus spp., 6 Salmonella spp., and one from each genus including Escherichia, Acinetobacter, Pseudomonas, Proteus, Clostridioides, Candida, Brucella, Burkholderia, Francisella, Yersinia, Moraxella, Vibrio, Shigella, Serratia, Citrobacter, and Haemophilus (spp.) were discussed in the review for their identification using the above-mentioned techniques. Among all the identified microorganisms, 21% of studies have been conducted for the identification of E. coli, 14% for S. aureus followed by 37% for other microorganisms.     

The glucocorticoid derivative with the phthalimide group cationic nanocrystal for ophthalmic application: a design space development approach

The glucocorticoid derivative of budesonide with a phthalimide group is a drug candidate to treat inflammatory eye diseases; nevertheless, it presents low water solubility. Drug nanocrystals have been proposed to overcome this hurdle. The development of an innovative ophthalmic anti-inflammatory nanosuspension was performed using a design space approach. We obtained the particle size reduction of this glucocorticoid derivative on a nanometer scale (approximately 165.0 nm), applying wet bead milling on a super reduced scale. The design of experiment supported the optimization of the formula evaluating the parameters that influence reducing the particle size and also allowed determining the design space. Considering the two statistical models developed and the size range obtained, we proposed that the optimized formulation for the glucocorticoid derivative nanosuspension may be 1.0 wt% glucocorticoid derivative and 0.092 wt% cetylpyridinium chloride. This formulation was characterized by the morphological, physical–chemical, and mucoadhesive in vitro test and showed potential for ophthalmic use with reduced frequency of product application, improved efficiency, and safety, which may promote better patient compliance.     

Microfluidics and electrochemistry: an emerging tandem for next-generation analytical microsystems

Microfluidic and electrochemical technologies have been at the forefront of the development of emerging analytical microsystems. Microfluidics and electrochemistry show a synergistic relationship, empowering their inherent features. Thus, integration of microfluidics and electrochemical (bio)sensors is envisioned as a powerful tandem for boosting the next generation of lab-on-a-chip platforms, including point-of-care and point-of-need systems. In this review, a general overview of the advantages, drawbacks, and gaps as well as remaining challenges and future trends of coupling microfluidics and electrochemical cells is presented. Special attention is given to the manufacturing and scale-up of the integrated devices and all those aspects that can push on the development of true lab-on-a-chip platforms for reaching the industrial domain and actual commercialization.     

Regio- and stereoselectivity of the 1,3-dipolar cycloaddition of azomethine ylides to (E)-3-(2-oxo-2-(pyren-1-yl)ethylidene)indolin-2-ones: A combined experimental and theoretical study

Functionalized oxindoles and pyrrolizidines form the central structural framework for numerous natural products with extensive biological and pharmacological applications. The requirement for high regio- and stereoselectivity is the main obstacle in the synthesis of such five-membered heterocycles. Multicomponent cycloaddition reactions often provide an efficient and straightforward approach for the preparation of specific regio- and stereoisomers. In this article, the regio- and stereochemistry of the polar [3 + 2]-cycloaddition (32CA) reaction of azomethine ylides prepared by the reaction of isatin derivatives and L-proline with a series of (E)-3-(2-oxo-2-(pyren-1-yl)ethylidene)indolin-2-ones was investigated by experimental and theoretical methods. Among the isatin and (E)-3-(2-oxo-2-(pyren-1-yl)ethylidene)indolin-2-one derivatives, a remarkable inversion of regioselectivity was observed in the 32CA reaction of azomethine ylide generated by the reaction of L-proline and 5-chloroisatin or N-methyl-5-chloroisatin with (E)-5-chloro-3-(2-oxo-2-(pyren-1-yl)ethylidene)indolin-2-one. The regio- and stereochemical assignment of the structures of the cycloaddition products was determined by one- and two-dimensional (1D&2D) homonuclear and heteronuclear correlation nuclear magnetic resonance spectroscopy. The molecular mechanism as well as the regio- and stereoselectivity of the cycloaddition were investigated by means of global and local reactivity indices and a density functional theory (DFT) and explained in detail on the basis of the transition state stabilities of the reactants.     

Synthesising injectable molecular self-curing polymer from monomer derived from lignocellulosic oil palm empty fruit bunch biomass: A review on treating Osteoarthritis

Osteoarthritis (OA) is a chronic and irreversible degenerative joint disease that most commonly affects individuals in their forties and fifties worldwide due to the continuously increasing life expectancy. Although joint replacement is an effective remedy for severe end-stage OA, the functional outcomes could be unsatisfactory, while the implants might have a limited lifespan. Due to the drawbacks and limitations of the joint replacement approach, bone Tissue Engineering (TE) is one of the promising bone tissue regeneration technologies that aid in cartilage repair and regeneration and has attracted the attention of experts. The advanced development of biopolymers, in particular biopolymer derived from Oil Palm Empty Fruit Bunch (OPEFB), has been utilised in the fabrication of scaffolds that serve as a crucial component in bone TE. The abundant supply of OPEFB biomass and the increasing trend of converting waste into wealth for environmental sustainability have also provided the opportunity and interest to fully apply biopolymer-derived materials for bone scaffolding and other applications. Therefore, this paper aimed to provide a review of the biopolymers derived from OPEFB for the treatment of OA and other related applications. A brief overview of the biomass sources in Malaysia was presented, followed by a discussion on the chemical compositions and pre-treatment methods of OPEFB by using organosolv pre-treatment and enzymatic hydrolysis for maximum glucose recovery, monomer derived from cellulose OPEFB and synthesizing self-curing polymer scaffold. Additionally, a detailed review of the polymeric biomaterials in bone TE for the fabrication of scaffolds were included in this review. Most importantly, the paper described the potential use of injectable polymeric biomaterials that provide a significant benefit in orthopaedic applications. Overall, this paper provides a perspective on the potential of OPEFB-derived injectable scaffolds as an alternative OA treatment and future bone TE applications.     

Microneedles-based electrochemical sensors: New tools for advanced biosensing

Electrochemical biosensors are used worldwide as analytical tools from laboratory applications to market products. The performance of electrochemical sensing can be boosted by adopting the microneedle (MN) geometry as an innovative configuration of standard electrodes. MNs can be miniaturized, easily functionalized, and properly designed for specific aim monitoring, but most of all, they allow a low invasive controlling tool for growth and for environment influence in plant and a painless door to human body fluids where target analytes can be detected, overcoming the natural barrier of the skin. In this review, the very recent developments in MN-based electrochemical biosensing published in the literature are summarized.     

Conjugate polymer-based membranes for gas separation applications: current status and future prospects

Conjugate polymers provide the possibility of exploiting both the chemical and physical attributes of the polymers for membrane-based gas separation. The presence of delocalized π electrons provides high chain stiffness with low packing density, thus making the membrane a rigid structure that favors facilitated transport. Historically, the polymeric membranes were constrained by the tradeoff relationship between gas permeability and gas selectivity. So, different methods were investigated to prepare the membranes that can overcome the limitation. In recent years, electroconductive polymeric membranes have gained attention with their enhanced transportation properties combining the separation behavior depending on both molecular size discrimination as well as the facilitated transport. They offer better selectivity toward polar gases such as CO₂ because of the increased solubility. This review is aimed to provide a literature survey on gas separation using conjugate polymers such as polyaniline, polypyrrole, and some derivatives of polythiophenes. It contains various methods used by different researchers to enhance the gas separation properties of the membranes with improved mechanical and thermal stability such as changing the morphology and membrane preparation methods. In addition, it provides the pros and cons of various factors affecting the conjugate polymer membrane performance. The major challenges and future work that can be done in improving the transportation properties through the membrane to achieve viable membranes are also discussed so that they can be used for commercial and practical applications in the future.     

Synthetic electrically driven colloids: A platform for understanding collective behavior in soft matter

The collective motion of synthetic active colloids is an emerging area of research in soft matter physics and is important both as a platform for fundamental studies ranging from non-equilibrium statistical mechanics to the basic principles of self-organization, emergent phenomena, and assembly underlying life, as well as applications in biomedicine and metamaterials. The potentially transformative nature of the field over the next decade and beyond is a topic of critical research importance. Electrokinetic active colloids represent an extremely flexible platform for the investigation and modulation of collective behavior in active matter. Here, we review progress in the past five years in electrokinetic active systems and related topics in active matter with important fundamental research and applicative potential to be investigated using electrokinetic systems.     

Photocatalytic remediation of persistent organic pollutants (POPs): A review

The release of persistent organic pollutants (POPs) into the environment is an issue of global concern, as the chemicals are stable over a prolonged period resulting in their accumulation in many animals and plants. Although POPs are banned in several countries, many chemicals have been proposed as POP candidates to be added to the existing compounds as defined by the United Nations Stockholm Convention committee. To address the safe disposal and clean-up of such chemicals, new, and especially cost-effective, remediation technologies for POPs are urgently required. This review focuses on existing POPs and the types of remediation processes available for their removal. Particular attention is paid towards photocatalysis using nanocatalysts in this review, due to their effectiveness towards POP degradation, technological feasibility, and energy and cost-efficiency. The underlying principles and the key mechanisms of the photocatalysts based on TiO₂ based materials, metal oxides, light-assisted Fenton systems, framework materials e.g. metal-organic frameworks and polyoxometalates, including metal-free and hybrid photocatalysts for POPs cleanup are described for advance applications in solving the POPs contamination in the environment. The improvements of photocatalytic performance especially the POPs removal mechanism using the conventional and modified process, the design and optimization of photoreactors, and the integration technology are the critical challenges for the emerging pollutants and require intensive research for the forthcoming future.     

Exogenous pulmonary surfactant: A review focused on adjunctive therapy for severe acute respiratory syndrome coronavirus 2 including SP-A and SP-D as added clinical marker

Type I and type II pneumocytes are two forms of epithelial cells found lining the alveoli in the lungs. Type II pneumocytes exclusively secrete ‘pulmonary surfactants,’ a lipoprotein complex made up of 90% lipids (mainly phospholipids) and 10% surfactant proteins (SP-A, SP-B, SP-C, and SP-D). Respiratory diseases such as influenza, severe acute respiratory syndrome coronavirus infection, and severe acute respiratory syndrome coronavirus 2 infection are reported to preferentially attack type II pneumocytes of the lungs. After viral invasion, consequent viral propagation and destruction of type II pneumocytes causes altered surfactant production, resulting in dyspnea and acute respiratory distress syndrome in patients with coronavirus disease 2019. Exogenous animal-derived or synthetic pulmonary surfactant therapy has already shown immense success in the treatment of neonatal respiratory distress syndrome and has the potential to contribute efficiently toward repair of damaged alveoli and preventing severe acute respiratory syndrome coronavirus 2–associated respiratory failure. Furthermore, early detection of surfactant collectins (SP-A and SP-D) in the circulatory system can be a significant clinical marker for disease prognosis in the near future.     

Polypept(o)ide-based bactericides: weapons against antibiotic-resistant bacterial infections

Emerging antibiotic resistance in bacterial pathogens has necessitated the development of alternative ‘outside of the box’ antimicrobial therapeutics. Polypept(o)ide-based bactericides with chemical structures mimicking antimicrobial host defense peptides have emerged as promising candidates for treating antibiotic-resistant and recurring infections. This review summarizes the recent advances in membrane-active polypept(o)ide-based bactericides in the treatment of antibiotic-resistant bacterial infections associated with the physical disruption of bacterial cell walls/cell membranes. Among these polypept(o)ide-based bactericides, nonantibiotic treatment strategies are employed to combat lethal bacterial strains resulting from acquired antibiotic resistance and biofilm formation, featuring the capacity to evade acquired antibiotic resistance-related mechanisms and to alleviate the emergence of drug resistance. Emphasis will focus on the typical polypept(o)ides with diverse molecular conformations (e.g., linear, brush-like, and star-shaped) and various chemical structures of monomers (e.g., α-amino acid, β-amino acid, and N-substituted glycine) that are central to the performance of antimicrobial polypept(o)ides. Finally, a brief discussion of the key challenges and prospects of polypept(o)ide-based bactericides is presented.     

Study of electrodeposited zinc selenide (ZnSe) nanostructure thin films for solar cell applications

Electrodeposition approach was used to grow the ZnSe nanostructure on indium doped tin oxide (ITO) layered glass substrate. Due to low cost and high degree of absorption, binary semiconductors made from chalcogens such as CdSe, ZnO, ZnS and ZnSe provide significant features in photovoltaic and photoelectrochemical cells. The structural and morphological properties of deposited nanostructures were examined by XRD and SEM. X-ray diffraction analysis informed about cubic structure with a preferred orientation and the calculated crystal size was approximately 75 nm. The optical properties were examined by UV–visible absorbance spectra and optical band gap was measured using Tauc plot. The deposited ZnSe nanostructure has direct band gap ∼2.52 eV at room temperature which was less than 2.82 eV which is the band gap of bulk ZnSe. Investigations also focused on additional qualities like excellent optical transmission, low electrical resistance, and good photosensitivity. Because of the presence of defect states in the deposited nanostructure, the band gap energy is smaller than that of bulk material. The current-voltage characteristics were measured in dark mode and under illumination of normal tungsten filament light and LED. There was notable change in the current for both normal light and LED in comparison to dark mode. The findings of all the characterization methodologies suggested that for the production of solar cells low cost ZnSe may be used as an alternative environment friendly Cd-free window layer.     

Modified QuEChERS method for phenolic compounds determination in mustard greens (Brassica juncea) using UHPLC-MS/MS

A modified QuEChERS method (Quick, Easy, Cheap, Effective, Rugged, and Safe) for the determination of fifteen phenolic compounds in mustard greens (Brassica juncea) using ultra-high-performance liquid chromatography coupled to tandem mass spectrometry (UHPLC-MS/MS) analysis was developed. The QuEChERS partitioning step and dispersive solid phase extraction (d-SPE) clean-up sorbents were investigated, aimed at phenolic compound extraction and pigment removal, respectively. QuEChERS acetate version combined with 25 mg of diatomaceous earth (DE) and 5.0 mg of graphitized carbon black (GCB) provided the best conditions for sample preparation of the target compounds. Under the optimized conditions, all phenolic compounds showed good linearity (r ≥ 0.99) over the concentration range of 0.1 to 8000 μg kg⁻¹, and the quantification limits were in the range of 0.06–230 μg kg⁻¹. The spectrophotometric analysis showed that the clean-up step promoted a significant removal of chlorophyll, which is the major pigment present in the sample. Furthermore, antioxidant activity analysis was also carried out after the clean-up step and, together with chromatographic data, showed that no significant retention of the phenolic compounds occurs in the clean-up step. Two mustard greens varieties – Southern Giant Curled (SGC) and Florida Broadleaf (FB) - were analyzed with the proposed method. Seven phenolic compounds (4-hydroxybenzoic, p-coumaric, ferulic and sinapic acids, naringenin, apigenin and kaempferol) were found in both varieties, the greatest abundance being for sinapic acid (1261.5 ± 23 μg kg⁻¹ in SGC and 1235.5 ± 26 μg kg⁻¹ in FB) and ferulic acid (2861 ± 24 μg kg⁻¹ in SGC and 3204.5 ± 45 μg kg⁻¹ in FB).