RSC Advances最新文献

In traditional TEMPO oxidation systems, the high cost of TEMPO catalysts has been a significant barrier to the industrialization of oxidized CNF. From an economic perspective, presenting the characteristics of various CNFs produced with the oxidation systems with reduced catalyst usage could facilitate the industrial application of CNF across a wide range of fields. In this study, it was demonstrated that reducing the amount of TEMPO catalyst used (from 0.1 to 0.05 mmol g⁻¹) in a conventional oxidation system increased the carboxylate content by approximately 6.3%. Furthermore, the activation of hydroxyl amine TEMPO, which is generated after the oxidation reaction of cellulose, was enhanced by adjusting the dosage of the inexpensive oxidant NaClO, leading to a 20% improvement in carboxylate content. This suggests that controlling the amount of NaClO as an oxidant can be a key parameter in adjusting the dosage of TEMPO to achieve the targeted degree of surface substitution. Results from the dispersion stability, UV-transmittance, and morphological properties of TEMPO-oxidized CNF using microfluidizing treatment showed that high carboxylate content plays a crucial role in producing high-purity CNF suspensions, which are small, uniform, and free from microfibers. Additionally, by varying the number of mechanical treatments applied to the oxidized cellulose, various types of CNF suspensions with different mean widths were obtained. We expect that these findings offer meaningful insights to end-users seeking a breakthrough in the performance limitations of final applications using cellulose nanomaterials.

Superhydrophobic coatings with remarkable water repellence have emerged as an increasingly prominent field of research with the growth of the material engineering and coating industries. Superhydrophobic coatings address the requirements of several application areas with characteristics including corrosion resistance, drag reduction, anti-icing, anti-fogging, and self-cleaning properties. Furthermore, the range of applications for superhydrophobic coatings has been substantially broadened by the inclusion of key performance features such as flame retardancy, thermal insulation, resistance to water penetration, UV resistance, transparency, anti-reflection, and many more. Numerous research endeavours have been focused on biomimetic superhydrophobic materials because of their distinct surface wettability. To develop superhydrophobic coatings with a long lifespan, scientists have refined the processes of material preparation and selection. To accomplish water repellency, superhydrophobic coatings are usually fabricated using harmful fluorinated chemicals or synthetic polymers. Utilising materials derived from biomass offers a sustainable alternative that uses renewable resources in order to eliminate the consumption of these hazardous substances. This paper provides an insight of several researches reported on the construction of superhydrophobic coatings using biomass materials such as lignin, cellulose, chitosan and starch along with the techniques used for the constructing superhydrophobic coatings. This study is a useful resource that offers guidance on the selection of various biobased polymers for superhydrophobic coatings tailored to specific applications. The further part of the paper put a light on different application of superhydrophobic coatings employed in various disciplines and the future perspectives of the superhydrophobic coatings.

Retraction of ‘Short polyethylene glycol chains densely bound to soft nanotube channels for inhibition of protein aggregation’ by N. Kameta et al., RSC Adv., 2016, 6, 36744–36750, https://doi.org/10.1039/C6RA06793J.

Two novel uranyl complexes were synthesized using bis-pyrazolyl methane ligands. The complexes were characterized by several spectroscopic techniques, including UV-Vis, IR, NMR, mass spectrometry, fluorescence, electrochemical, and thermogravimetric analysis. The solid-state structure of the complex C1 was determined with the help of single-crystal X-ray diffraction studies. The complexes C1 and C2 efficiently catalyse the oxidation of 3,5-di-tert-butyl catechol and 2-aminophenol in the atmospheric air, imitating the catalytic activity of the catechol oxidase and phenoxazinone synthase enzymes. The kinetic parameters and the catalytic efficiency (K_cat/K_M) of the reactions were calculated. Formation of organic free radicals in the catalytic reactions was confirmed by EPR spectroscopy. The interaction of these complexes with the protein, bovine serum albumin, was investigated by using UV-Vis and fluorescence spectral analysis. The cytotoxicity of the complexes against MDAMB-231 and A549 cell lines was investigated, and IC₅₀ values were determined.

Herein, we report the synthesis, characterization, supramolecular gelation and multiple applications of 6-aminocoumarin-derived Schiff bases 1 and 2. Both Schiff bases underwent gelation in DMF–H₂O (2 : 1, v/v), DMSO–H₂O (2 : 1, v/v) and dioxane–H₂O (2 : 1, v/v) involving weak forces. Furthermore, the gels were stable and exhibited good viscoelastic properties. The storage modulus (G′) of each gel was considerably higher than its loss modulus (G′′). The higher value of the crossover point and lower value of tan δ for the gel of Schiff base 2 compared to the gel of Schiff base 1 demonstrated the better gelation behaviour of 2 than that of 1 in DMF–H₂O (2 : 1, v/v). Further, iodo-analogue 2 exhibited cross-linked helical morphology, whereas non-iodo analogue 1 exhibited long chain fibrous morphology, as observed via FESEM. These differences in morphology and viscoelastic behaviors were attributed to the iodo group present in 2, which influenced its aggregation involving halogen bonding. To demonstrate their application, the DMF–H₂O (2 : 1, v/v) gels of both 1 and 2 recognized CN⁻ over a series of other anions by exhibiting a gel-to-sol phase change. Besides anion sensing, gels 1 and 2 selectively detected Fe³⁺ and Cu²⁺ ions over other metal ions via a gel-to-gel colour change. Finally, CN⁻-treated solutions of 1 and 2 allowed the successful detection of CO₂ by the naked eye. Moreover, the detection was possible using a test-kit method.

The energy crisis is the most urgent issue facing contemporary society and needs to be given top priority. As energy consumption rises, environmental pollution is becoming a serious issue. Direct methanol fuel cells (DMFCs) have emerged as the most promising energy source for a variety of applications such as electric vehicles and portable devices. Unfortunately, the kinetics of methanol oxidation is slow and needs an electrocatalyst to improve the reaction kinetics and the overall fuel cell efficiency. Herein, a straightforward hydrothermal procedure was utilized to prepare copper, nickel, and cobalt-based MOF composites by altering the elemental molar ratios. Cu-MOF (MOFP1), Cu/Ni-MOF (MOFP2), and Cu/Ni/Co-MOF (MOFP3) were prepared after carbonization and characterized using several key techniques such as FTIR, XRD, SEM, and EDX. The SEM analysis reveals that the morphology of MOFP1 is spherical aggregated particles, while that of MOFP2 or MOFP3 is in the form of nanoflakes and nanoflowers. Moreover, upon application of these composites as electrocatalysts for methanol electro-oxidation in an alkaline medium of 1 M NaOH using cyclic voltammetry (CV) and chronoamperometry (CA) tests, the electrochemical performance of MOFP2 in 1 M methanol exhibits the best performance for methanol oxidation with a current density reaching 38.77 mA cm⁻² at a scan rate of 60 mV s⁻¹. This can be attributed to the unique porous open flower structure and the synergistic effect between copper, nickel, and 2-aminoterephthalic acid which develop its catalytic activity.

Non-steroidal anti-inflammatory drugs NSAIDs are widely used for managing various conditions including pain, inflammation, arthritis and many musculoskeletal disorders. NSAIDs exert their biological effects by inhibiting the cyclooxygenase (COX) enzyme, which has two main isoforms COX-1 and COX-2. The COX-2 isoform is believed to be directly related to inflammation. Based on structure–activity relationship (SAR) studies of known selective COX-2 inhibitors, our aim is to design and synthesize a novel series of 2-benzamido-N-(4-substituted phenyl)thiophene-3-carboxamide derivatives. These derivatives are intended to be selective COX-2 inhibitors through structural modification of diclofenac and celecoxib. The compound 2-benzamido-5-ethyl-N-(4-fluorophenyl)thiophene-3-carboxamide VIIa demonstrated selective COX-2 inhibition with an IC₅₀ value of 0.29 μM and a selectivity index 67.24. This is compared to celecoxib, which has an IC₅₀ value of 0.42 μM and a selectivity index 33.8. Molecular docking studies for compound VIIa displayed high binding affinity toward COX-2. Additionally, the suppression of protein denaturation with respect to albumin was performed as an indicative measure of the potential anti-inflammatory efficacy of the novel compounds. Compound VIIa showed potent anti-inflammatory activity with 93% inhibition and an IC₅₀ value 0.54 μM. In comparison, celecoxib achieved 94% inhibition with an IC₅₀ value 0.89 μM. Although molecule VIIa demonstrated significant in vitro anti-inflammatory activity, adhered to Lipinski's “five rules” (RO5) and exhibited promising drug-like properties, it showed indications of poor in vivo activity. This limitation is likely due to poor aqueous solubility, which impacts its bioavailability. This issue could be addressed by incorporating the drug in niosomal nanocarrier. Niosomes were prepared using the thin-film hydration technique. These niosomes exhibited a particle size of less than 200 nm, high entrapment efficiency, and an appropriate drug loading percentage. Transmission electron microscopy (TEM) and differential scanning calorimetry (DSC) studies revealed that the niosomes were spherical and demonstrated compatibility of all of its components. The drug release study indicated that the pure drug had limited practicality for in vivo use. However, incorporating the drug into niosomes significantly improved its release profile, making it more suitable for practical use.

Nanotechnology is the platform with the greatest promise for scientific advancements. One of the advancement is improvement in photocatalytic and antibacterial performance. This work was undertaken to synthesize un-doped and silver (Ag) doped zinc oxide (ZnO) nanoparticles (NPs) using an inexpensive wet chemical method and to investigate the structural and optical properties, photocatalytic and antibacterial activity. The structural analysis from X-ray diffraction (XRD) pattern of un-doped and Ag-doped ZnO NPs displayed hexagonal wurtzite crystal structure and shifting in the peak position confirms the incorporation of Ag in ZnO lattice. Morphological study done by scanning electron microscope reveals spherical shaped NPs and an increase in grain size with Ag doping, the HRTEM images showed the nanocrystalline nature of particle. The Raman spectra showed variation in vibrational characteristics of the nanoparticles with Ag doping. The functional groups were analyzed using Fourier transform-infrared spectroscopy (FTIR). The optical properties were investigated by UV-visible and photoluminescence (PL) spectroscopic techniques. The Ag-doped ZnO NPs have a notably lower band gap than that of un-doped ZnO NPs, i.e. from 3.04 eV to 2.81 eV as studied by UV-visible spectra. The PL study showed decrease in intensity at near band edge emission with increase in Ag doping concentration indicating reduction in the free charge carrier recombination. These variations in the properties play major role in the enhancement of photocatalytic and antibacterial activity with increase in Ag doping concentration as compared to un-doped zinc oxide nanoparticles. The photo degradation efficiency of 99.12 ± 1% against Methylene Blue dye was achieved in the shortest period of 45 minutes ever reported when irradiated under the solar light and efficiency of 97.33 ± 1% was achieved in 15 min under Xenon Short Arc lamp. The antibacterial study was conducted using the Agar well diffusion method where the diameter of the zone of inhibition (ZOI) was increased from 14 mm to 20 mm and 13 mm to 18 mm against the bacteria Escherchia coli and Bacillus subtilis respectively, rendering this material suitable for photocatalytic degradation and antibacterial applications.

Isobavachalcone (IBC) is a natural prenylated flavonoid containing chalcone and prenyl chain moieties with a wide range of biological and pharmacological properties. In this work, we synthesized structurally diversified derivatives (IBC-2 to IBC-10) from the natural prenylated chalcone IBC isolated from Psoralea corylifolia and assessed their antibacterial potency against the Gram-positive and Gram-negative bacterial strains S. aureus ATCC 29213, MRSA ATCC 15187, E. coli ATCC25922 and P. aeruginosa ATCC 27853. IBC and IBC-2 exhibited a minimum inhibition concentration (MIC) of 5.0 μM against S. aureus ATCC 29213, whereas IBC-3 exhibited a broad-spectrum activity against Gram-positive and Gram-negative pathogens. Cytotoxicity assessments on the murine RAW 264.7 macrophage cell line revealed minimal to moderate cytotoxicity for IBC-2 and IBC-3 with a favorable selectivity index (>10). Time- and concentration-dependent studies further supported the bactericidal nature of the compounds, as IBC, IBC-2, and IBC-3 exhibited concentration-dependent killing of S. aureus in a time-dependent manner. Furthermore, combination studies, SEM analysis, and PI staining suggest that IBC-3's mechanism of action targets the bacteria's cytoplasmic membrane or cell wall. The bioactive compounds displayed promising drug-like characteristics and a favorable pharmacokinetic profile (ADME-Tox), indicating a projected high oral bioavailability. Structure–activity relationships (SARs) drawn from this study reveal that a prenyl chain at the A-ring and hydroxy functional groups attached to the aromatic rings of chalcone scaffolds are responsible for this antibacterial potential, which will be helpful in the future discovery and development of antibiotics from natural products to overcome the antibiotic resistance crisis.

Calcium phosphate (CaP) minerals have shown great promise as bone replacement materials due to their similarity to the mineral phase of natural bone. In addition to biocompatibility and osseointegration, the prevention of infection is crucial, especially due to the high concern of antibiotic resistance. In this context, a controlled drug release as well as biodegradation are important features which depend on the porosity of CaP. An increase in porosity can be achieved by using nanoparticles (NPs), which can be processed to supraparticles, combining the properties of nano- and micromaterials. In this study, Cu-doped CaP supraparticles were prepared to improve the bone substitute properties while providing antibacterial effects. In this context, a modified sol–gel process was used for the synthesis of CaP NPs, where a Ca/P molar ratio of 1.10 resulted in the formation of crystalline β-tricalcium phosphate (β-TCP) after calcination at 1000 °C. In the next step, CaP NPs with Cu²⁺ (0.5–15.0 wt%) were processed into supraparticles by a spray drying method. Cu release experiments of the different Cu-doped CaP supraparticles demonstrated a long-term sustained release over 14 days. The antibacterial properties of the supraparticles were determined against Gram-positive (Bacillus subtilis and Staphylococcus aureus) and Gram-negative (Escherichia coli) bacteria, where complete antibacterial inhibition was achieved using a Cu concentration of 5.0 wt%. In addition, cell viability assays of the different CaP supraparticles with human telomerase-immortalized mesenchymal stromal cells (hMSC-TERT) exhibited high biocompatibility with particle concentrations of 0.01 mg mL⁻¹ over 72 hours.