Xanthan and gum acacia modified olive oil based nanoemulsion as a controlled delivery vehicle for topical formulations

In this study, olive oil nanoemulsion modified with xanthan gum and gum acacia was explored as a potential controlled topical delivery vehicle. Oil-in-water nanoemulsion formulated with optimized composition of olive oil, tween 80, and water was used as the drug carrier and further modified with gum. Effect of gum on nanoemulsion different physiochemical characteristics, stability, rheology, drug release and encapsulation efficiency were investigated. Results showed that developed nanoemulsion behaved as low viscosity Newtonian fluid and released 100 % drug within 6 h. Modification with xanthan and gum acacia had significantly improved formulation viscosity, drug encapsulation efficiency (>85 %) and controlled drug release up to 40 % with release pattern following Korsmeyer-Peppas model. Additionally, xanthan gum modified formulation exhibited shear thinning rheology by forming an extended network in the continuous phase, whereas gum acacia modified formulation behaved as Newtonian fluid at high shear rate (>200 s-1). Furthermore, xanthan gum modified formulations had improved zeta potential, stability, monodispersity, and hemocompatibility and showed high antibacterial activity against S. aureus than gum acacia modified formulations. These results indicate the higher potential of xanthan gum modified formulation as a topical delivery vehicle. Moreover, skin irritation test demonstrated the safety of developed formulations for topical application.

Jute Stick-Derived Cellulose-Based Hydrogel: Synthesis, Characterization, and Methylene Blue Removal from Aqueous Solution

In this work, microcrystalline cellulose (MCC) was isolated from jute sticks and sodium carboxymethyl cellulose (Na-CMC) was synthesized from the isolated MCC. Na-CMC is an anionic derivative of microcrystalline cellulose. The microcrystalline cellulose-based hydrogel (MCCH) and Na-CMC-based hydrogel (Na-CMCH) were prepared by using epichlorohydrin (ECH) as a crosslinker by a chemical crosslinking method. The isolated MCC, synthesized Na-CMC, and corresponding hydrogels were characterized by Fourier transform infrared (FTIR), X-ray diffraction (XRD), scanning electronic microscopy (SEM), and energy dispersive spectroscopy (EDS) for functional groups, crystallinity, surface morphology, and composite elemental composition, respectively. Pseudo-first-order, pseudo-second-order, and Elovich models were used to investigate the adsorption kinetics. The pseudo-second-order one is favorable for both hydrogels. Freundlich, Langmuir, and Temkin adsorption isotherm models were investigated. MCCH follows the Freundlich model (R2 = 0.9967), and Na-CMCH follows the Langmuir isotherm model (R2 = 0.9974). The methylene blue (MB) dye adsorption capacities of ionic (Na-CMCH) and nonionic (MCCH) hydrogels in different contact times (up to 600 min), initial concentrations (10-50 ppm), and temperatures (298-318 K) were investigated and compared. The maximum adsorption capacity of MCCH and Na-CMCH was 23.73 and 196.46 mg/g, respectively, and the removal efficiency of MB was determined to be 26.93% for MCCH and 58.73% for Na-CMCH. The Na-CMCH efficiently removed the MB from aqueous solutions as well as spiked industrial wastewater. The Na-CMCH also remarkably efficiently reduced priority metal ions from an industrial effluent. An effort has been made to utilize inexpensive, readily available, and environmentally friendly waste materials (jute sticks) to synthesize valuable adsorbent materials.

Poly[(2-methacryloyloxy)Ethyl]Trimethylammonium Chloride Supported Cobalt Oxide Nanoparticles as an Active Electrocatalyst for Efficient Oxygen Evolution Reaction

To combat with energy crisis considering clean energy, oxygen evolution reaction (OER) is crucial to implement electrolytic hydrogen fuel production in real life. Here, straightforward chemical synthesis pathways are followed to prepare cobalt tetraoxide nanoparticles (Co3 O4 NPs) in an alkaline OER process using poly[(2-methacryloyloxy)ethyl]trimethylammonium chloride (Co3 O4 NPs@PMTC) as support to prevent aggregation. In material characterization, the X-ray diffraction (XRD) pattern confirms the crystallinity of the synthesized Co3 O4 NPs@PMTC, and Raman spectroscopy indicates that the Co3 O4 NPs contain cubic close-packed oxides. The morphological analysis reveals the wrinkle-like disruption which is distributed evenly owing to the folded nanosheet arrays. Energy-dispersive X-ray spectroscopy indicates the presence of a significant number of cobalt atoms in the Co3 O4 NPs, and elemental mapping analysis demonstrates the composition of the NPs. At a current density of 10 mA cm-2 , oxygen is emitted at 1.67 V delivering an overpotential of 440 mV. This unique structure of Co3 O4 NPs@PMTC provides beneficial functions that are responsible for a large number of active sites and the rapid release of oxygen gas with long-term stability. Through kinetic study, we found a Tafel slope of 48.9 mV dec-1 which proves the catalytic behavior of Co3 O4 NPs@PMTC is promising toward the OER process.

Synthesis of Polymeric Surfactant Containing Bis-cationic Motifs as a Highly Efficient acid Corrosion Inhibitor for C1018 Carbon steel

The present study describes the synthesis and characterization of a Poly(methyldiallylammonium chloride)-based surfactant containing bis-cationic motifs 9 by a series of reactions. The synthesized polymer 9 was characterized by FTIR...

Acridine and Its Derivatives: Synthesis, Biological, and Anticorrosion Properties

The phenomenon of corrosion threatens metallic components, human safety, and the economy. Despite being eco-friendly and promising as a corrosion inhibitor, acridine has not been explored to its full potential. In this review, we have discussed multiple biological activities that acridines have been found to show in a bid to prove that they are environmentally benign and much less toxic than many inhibitors. Some synthetic routes to acridines and substituted acridines have also been discussed. Thereafter, a multitude of acridines and substituted acridines as corrosion inhibitors of different metals and alloys in various corrosive media have been highlighted. A short mechanistic insight into how acridine-based compounds function as corrosion inhibitors have also been included. We believe this review will generate an impression that there is still much to learn about previously reported acridines. In the wake of recent surges to find efficient and non-toxic corrosion inhibitors, acridines and their analogs could be an appropriate answer.

Recent Development in Laminar Transition Metal Dichalcogenides-based Membranes Towards Water Desalination: A Review

Transition metal dichalcogenides (TMDCs)-based laminar membranes have gained significant interest in energy storage, fuel cell, gas separation, wastewater treatment, and desalination applications due to single layer structure, good functionality, high mechanical strength, and chemical resistivity. Herein, we review the recent efforts and development on TMDCs-based laminar membranes, and focus is given on their fabrication strategies. Further, TMDCs-based laminar membranes for water purification and seawater desalination are discussed in detail. Finally, present their merits, limits and future challenges needed in this area.

Hydroquinone Decorated with Alkyne, Quaternary Ammonium, and Hydrophobic Motifs to Mitigate Corrosion of X-60 Mild Steel in 15 wt.% HCl

1-(6-Bromohexyloxy)-4-propargyloxybenzene upon quaternization with 3-dimethylamino-1-propanol and N,N-dimethyldodecylamine produced two new inhibitor molecules: N-[6-(4-Propargyloxyphenoxy)hexyl]-N,N-dimethyl-N-(3-hydroxypropyl)ammonium bromide (PHAB) and N-[6-(4-Propargyloxyphenoxy)hexyl]-N,N-dimethyl-N-dodecylammonium bromide (PDAB), respectively, in excellent yields. The inhibitor molecules were characterized by elemental analysis, Fourier transform infrared spectroscopy, ¹ H NMR, and ¹³ C NMR spectroscopy. The inhibitors were evaluated for X-60 mild steel corrosion in 15 wt.% HCl using different electrochemical and gravimetric techniques. The potentiodynamic polarization confirms both the inhibitors as mixed-type corrosion inhibitors. A low concentration (15 ppm) of PDAB has demonstrated excellent corrosion inhibition efficiencies of 97%, 98%, and 86% at 25 °C, 50 °C, and 70 °C, respectively, for 24 h exposure time. SEM and EDX spectra reveal that the adsorptions of corrosion inhibitors on X-60 mild steel create a protective film that serves as a barrier to mitigate the corrosion process. The X-ray photoelectron spectroscopy confirmed the chemical interaction between the corrosion inhibitors and mild steel, which was predicted by the Langmuir adsorption model. Assembly of inhibitive motifs of the alkyne, π-electron-rich aromatic, quaternary ammonium and C₁₂ alkyl chain hydrophobe in PDAB has augmented its inhibiting action.

Highly Efficient Permeation and Separation of Gases with Metal-Organic Frameworks Confined in Polymeric Nanochannels

This work demonstrates the confinement of porous metal-organic framework (HKUST-1) on the surface and walls of track-etched nanochannel in polyethylene terephthalate (np-PET) membrane using a liquid-phase epitaxy (LPE) technique. The composite membrane (HKUST-1/np-PET) exhibits defect-free MOF growth continuity, strong attachment of MOF to the support, and a high degree of flexibility. The high flexibility and the strong confinement of the MOF in composite membrane results from (i) the flexible np-PET support, (ii) coordination attachment between HKUST-1 and the support, and (iii) the growth of HKUST-1 crystal in nanoconfined geometries. The MOF has a preferred growth orientation with a window size of 3.5 Å, resulting in a clear cut-off of CO₂ from natural gas and olefins. The experimental results and DFT calculations show that the restricted diffusion of gases only takes place through the nanoporous MOF confined in the np-PET substrate. This research thereby provides a new perspective to grow other porous MOFs in artificially prepared nanochannels for the realization of continuous, flexible, and defect-free membranes for various applications.

Assessment of sulfonated homo and co-polyimides incorporated polysulfone ultrafiltration blend membranes for effective removal of heavy metals and proteins

Sulfonated homo and co- polyimide (sPI) were synthesized with new compositional ratios, and used as additives (0.5 wt%, 0.75 wt%, and 1.0 wt%) to prepare blend membranes with polysulfone (PSf). Flat sheet membranes for ultrafiltration (UF) were casted using the phase inversion technique. Surface morphology of the prepared UF membranes were characterized by atomic force microscopy (AFM) and scanning electron microscopy (SEM). Surface charge of the membranes were determined by zeta potential, and hydrophilicity was studied by contact angle measurement. The contact angle of the membrane decreased with increasing sPI additive indicates increasing the hydrophilicity of the blend membranes. Filtration studies were conducted for rejection of heavy metals (Pb2+ and Cd2+) and proteins (pepsin and BSA). Blend membranes showed better rejection than pure PSf membrane. Among the blend membranes it was observed that with increasing amount of sPIs enhance the membrane properties and finally, PSf-sPI5 membrane with 1 wt% of sPI5 showed the improved permeability (72.1 L m-2 h-1 bar-1), and the best rejection properties were found for both metal ions (≈98% of Pb2+; ≈92% of Cd2+) and proteins (>98% of BSA; > 86% of Pepsin). Over all, this membrane was having better hydrophilicity, porosity and higher number of sites to attach the metal ions. Its performance was even better than several-reported sulfonic acid based UF membranes. All these intriguing properties directed this new UF membrane for its potential application in wastewater treatment.

Synthesis, characterization and electrochemical analysis of cysteine modified polymers for corrosion inhibition of mild steel in aqueous 1 M HCl

Butler's cyclopolymerization protocol was used to synthesize homo and copolymers of cysteine residues and diallyldimethylammonium chloride (DADMAC) using water as a solvent and excellent yields were obtained. The structural composition of the polymers was determined using nuclear magnetic resonance (NMR) and Fourier-transform infrared (FT-IR) spectroscopies. The thermal stability of the synthesized polymers was determined using thermogravimetric analysis (TGA). The corrosion efficiencies and adsorption characteristics of these polymers on mild steel were evaluated using gravimetric weight loss and potentiodynamic polarization, and electrochemical impedance spectroscopy (EIS). The copolymers of cysteine residues and DADMAC exhibited excellent inhibition efficiencies in arresting mild steel corrosion in 1 M hydrochloric acid (HCl) at 60 °C. The best fitted Langmuir, Temkin and Freundlich adsorption isotherms suggested that the adsorption process occurs through chemisorption and physisorption. The surface morphology of mild steel in the presence or absence of polymers was determined using atomic force microscopy (AFM), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX), and X-ray photoelectron spectroscopy (XPS). This systematic study might provide a way to design new inhibitor compounds that could be beneficial in the field of biomedical science as well as for anti-corrosion applications.

Mild steel framework embedded in corrosion inhibiting structural motifs.

Correction: Synthesis, characterization and electrochemical analysis of cysteine modified polymers for corrosion inhibition of mild steel in aqueous 1 M HCl

Correction for ‘Synthesis, characterization and electrochemical analysis of cysteine modified polymers for corrosion inhibition of mild steel in aqueous 1 M HCl’ by Mohammad A. Jafar Mazumder et al., RSC Adv., 2019, 9, 4277–4294.

Temperature-sensitive polymers for drug delivery

The ability to undergo rapid changes in response to subtle environmental cues make stimuli- responsive materials attractive candidates for minimally invasive, targeted and personalized drug delivery applications. This special report aims to highlight and provide a brief description of several of the significant natural and synthetic temperature-responsive materials that have clinical relevance for drug delivery applications. This report examines the advantages and disadvantages of natural versus synthetic materials and outlines various scaffold architectures that can be utilized with temperature-sensitive drug delivery materials. The authors provide a commentary on the current state of the field and provide their insight into future expectations for temperature-sensitive drug delivery, emphasizing the importance of the emergence of dual and multiresponsive systems capable of responding precisely to an expanding set of stimuli, thereby allowing the development of disease-specific drug delivery vehicles.

Mechanically enhanced microcapsules for cellular gene therapy

Microcapsules bearing a covalently cross-linked coating have been developed for cellular gene therapy as an improvement on alginate-poly(L-lysine)-alginate (APA) microcapsules that only have ionic cross-linking. In this study, two mutually reactive polyelectrolytes, a polycation (designated C70), poly([2-(methacryloyloxy)ethyl]trimethylammonium chloride-co-2-aminoethyl methacrylate hydrochloride) and a polyanion (designated A70), poly(sodium methacrylate-co-2-(methacryloyloxy)ethyl acetoacetate), were used during the microcapsule fabrication. Ca-alginate beads were sequentially laminated with C70, A70, poly(L-lysine) (PLL), and alginate. The A70 reacts with both C70 and PLL to form a approximately 30 microm thick covalently cross-linked interpenetrating polymer network on the surface of the capsules. Confocal images confirmed the location of the C70/A70/PLL network and the stability of the network after 4 weeks implantation in mice. The mechanical and chemical resistance of the capsules was tested with a "stress test" where microcapsules were gently shaken in 0.003% EDTA for 15 min. APA capsules disappeared during this treatment, whereas the modified capsules, even those that had been retrieved from mice after 4-weeks implantation, remained intact. Analysis of solutions passing through model flat membranes showed that the molecular weight cut-off of alginate-C70-A70-PLL-alginate is similar to that of alginate-PLL-alginate. Recombinant cells encapsulated in APA and modified capsules were able to secrete luciferase into culture media. The modified capsules were found to capture some components of regular culture media used during preparation, causing an immune reaction in implanted mice, but use of UltraCulture serum-free medium was found to prevent this immune reaction. In vivo biocompatibility of the new capsules was similar to the APA capsules, with no sign of clinical toxicity on complete blood counts and liver function tests. The increased stability of the covalently modified microcapsules coupled with the acceptable biocompatibility and permeability demonstrated their potential for use as immunoisolation devices in gene therapy.