The Royal Society of Chemistry最新文献

Lignin is an aromatic biopolymer found in plant cell walls and is the most abundant source of renewable aromatic carbon in the biosphere. Hence there is considerable interest in the conversion of lignin, either derived from agricultural waste or produced as a byproduct of pulp/paper manufacture, into high-value chemicals. Although lignin is rather inert, due to the presence of ether C-O and C-C linkages, several microbes are able to degrade lignin. This review will introduce these microbes and the enzymes that they use to degrade lignin and will describe recent studies on metabolic engineering that can generate high-value chemicals from lignin bioconversion. Catabolic pathways for degradation of lignin fragments will be introduced, and case studies where these pathways have been engineered by gene knockout/insertion to generate bioproducts that are of interest as monomers for bioplastic synthesis or aroma chemicals will be described. Life cycle analysis of lignin bioconversion processes is discussed.

Breast cancer is the fifth major cause of fatalities associated with cancer worldwide and in Pakistan, 34 066 female breast cancer cases were recorded in 2018. This study was designed to understand extracts of Cheiranthus cheiri (C. cheiri) and to evaluate the epigenetic modulation of microRNA expression for breast cancer therapy using a selected phyto-nanohybrid treatment. The phytochemical screening revealed the presence of potential phytochemicals and antioxidant scavenging activity in the C. cheiri extracts with a DPPH (2-diphenyl-1-picryl-hydroxyl) assay giving an IC₅₀ value of 20.63 μg mL⁻¹. GC-MS (gas chromatography-mass spectroscopy) analysis of the C. cheiri n-hexane extract detected 42 phytocompounds. Titanium oxide (TiO₂) nanoparticles were synthesized and characterized using XRD (X-ray diffraction), SEM (scanning electron microscopy) and EDX (energy dispersive X-ray spectrometry) to confirm the synthesis of anatase (tetragonal) TiO₂. The prepared nanoparticles were conjugated with the selected plant i.e., C. cheiri. The resulting phyto-nanohybrid was used for the subsequent treatment of breast cancer induced in a female rat model. The treatment groups were as follows: doxorubicin as the standard treatment, C. cheiri, TiO₂ and the phyto-nano hybrid treatment. After 8 weeks of treatment, the groups induced to exhibit breast cancer (with and without treatment) and the control groups were dissected and analysed for histopathological, haematological and microRNA expression. Histopathological examination revealed chronic inflammation in the dilated ducts and tumour embolus formation, thus confirming the presence of breast cancer in the DMBA-induced female rat model. MicroRNA expression analysis showed a statistically significant decrease in levels of miR-205 in the plasma of the breast cancer rat model compared to the control (p < 0.05). After treatment with the phyto-nano hybrid, a statistically significant increase in the expression of miR-205 was observed in the rat models induced to exhibit breast cancer compared to the rat model without any treatment (p < 0.05). The downregulation of miR-205 in the plasma of the breast cancer exhibiting model, as compared to the control, and its upregulation after treatment with the selected phyto-nano hybrid indicated its diagnostic and prognostic significance. It is concluded that the phyto-nano hybrid used in this study is effective against breast cancer induced female rat model. All the results support the finding that the selected phyto-nano hybrid has great potential as a possible therapeutic agent for the treatment of breast cancer.

Reinforced concrete (RC) constructions are seriously threatened by chloride-induced corrosion (CIC) and carbonation, which can result in structural degradation, safety issues, and financial losses. Electrochemical methods and microstructural analysis tests are some of the laboratory techniques used to examine key elements of CIC, such as the impact of different variables and the efficacy of mitigation solutions. In situ studies that make use of non-destructive testing, chloride profiling, and half-cell potential measurements offer important new insights into the long-term performance and causes of RC structure deterioration in real-world circumstances. Non-destructive approaches for CIC detection are emerging these days and provide fruitful results. Studies have focused on the use of these approaches for CIC detection on small specimens in the lab as well as on full-scale experiments in the field. This review covers both in situ monitoring and laboratory studies to provide a thorough analysis of CIC.

Since the discovery of penicillin, the forerunner of the most widely used class of antibiotics (i.e. β-lactams), natural compounds and their derivatives represented a major source of antibacterial therapeutic products whose availability enabled modern medical practices (invasive surgery, organ transplant, etc.). However, the relentless emergence of resistant bacteria is challenging the long-term efficacy of antibiotics, also decreasing their economic attractiveness for big pharma, leading to a significant decay in antibacterial development in the 21^st century and an increased use of last-resort drugs such as carbapenems or colistin. Indeed, bacteria evolved an arsenal of resistance mechanisms, leading to the emergence of totally-drug resistant isolates, already sporadically isolated among Gram-negative bacterial species. To face this deadly peril, it is fundamental to explore new ground-breaking approaches. In view of the significance of both β-lactam antibiotics and the production of one or more β-lactamases as the major resistance mechanism (especially in Gram-negative bacteria), we implemented an original approach to selectively deliver antibacterial zidovudine (AZT) exploiting the β-lactamase-mediated hydrolysis of a β-lactam-conjugate prodrug. The synthesis of the targeted pronucleosides was performed in 5-7 steps and based on an original Pd-catalyzed cross-coupling reaction. Enzymatic and microbiological evaluations were performed to evaluate the synthesized pronucleosides, yielding new insights into molecular recognition of β-lactamase enzymes. This approach would potentially allow a targeted and selective eradication of antibiotic-resistant β-lactamase-producing (opportunistic) pathogens, as the inactive prodrug is unable to harm the commensal microbial flora.

This paper presents functionalized magnetic nanoparticles (Fe₃O₄@Au MNPs) combined with the surface-enhanced Raman spectroscopy (SERS) technique for sensitive detection of colorectal cancer (CRC) protein biomarker carbohydrate antigen 19-9 (CA19-9). Fe₃O₄@Au MNPs were constructed by the PEI-mediated seed growth method. Then, the signal molecule 5-5'-dithiobis (succinimidyl-2-nitrobenzoic acid) was used as a bridging agent to link CA19-9 antibody, and the SERS sensor was prepared. Using this sensor, detection of CA19-9 can be realized with only a one step sampling reaction. Fe₃O₄@Au MNPs combine the advantages of magnetic materials and noble metal nanoparticles, effectively amplifying the signal by creating numerous "hot spots" within the Au particle gaps and enhancing magnetic enrichment. Consequently, this approach lowers the detection limit (LOD) and enhances detection sensitivity. The ratio of characteristic peak intensities I₁₃₉₂/I₁₀₆₉ was selected for calculation, and a linear equation was constructed with a LOD as low as 0.27 U mL^-1 by quantitative detections of the standard antigen. Finally, the sensor was used to analyze the clinical serum samples from CRC patients and healthy individuals, and the detection results were consistent with the actual results. This method exhibits notable advantages, including simplicity, high sensitivity, specificity, stability and reproducibility. It is expected to provide a new promising analytical method for clinical CA19-9 immunoassay.

This study investigates a class of materials known as polymer nanodielectrics, which are formed by incorporating ceramic fillers into polymers. These materials offer the unique advantage of tunable electrical and optical properties. The research focuses on the incorporation of high-purity stannic oxide nanoparticles (SnO₂ NPs) into a ternary blend matrix of hydroxypropyl methylcellulose (HPMC) and poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) using a solution casting method. Characterization techniques like X-ray diffraction (XRD) and Fourier-transform infrared spectroscopy (FT-IR) revealed alterations in the amorphous nature of the HPMC/PEDOT:PSS blend upon the introduction of SnO₂ NPs. These analyses also suggest the formation of interactions between the polymer and nanoparticles. Scanning electron microscopy (SEM) images confirmed the successful dispersion of SnO₂ NPs on the surface of the polymer blend, particularly at lower concentrations. The optical properties of the nanocomposite films were investigated using UV-vis spectrophotometry. This analysis allowed for the calculation of optical constants like the bandgap and refractive index. The results showed a dual-bandgap structure, with the direct and indirect bandgaps ranging from 4.92 eV to 4.26 eV and 3.52 eV to 1.68 eV, respectively. Electrical characterization using AC conductivity and dielectric permittivity measurements revealed a dependence on the SnO₂ NPs concentration within the frequency range of 0.1 Hz to 10 MHz. The relaxation processes and interfacial polarization effects within these nanocomposites are further discussed in the study. At a frequency of 10 Hz, the AC conductivity exhibited a significant increase, rising from 1.85 × 10⁻¹² S m⁻¹ to 1.04 × 10⁻⁹ S m⁻¹ upon the addition of 0.7 wt% SnO₂ NPs. These findings highlight the multifunctional nature of the developed nanocomposites. They hold promise for various applications, including UV blockers, optical bandgap tuners, and optical coatings in advanced optoelectronic devices. Additionally, their tunable high permittivity suggests potential use as dielectric substrates for next-generation, high-performance energy storage devices.

We present a simple and cost-efficient route for the preparation of sulfonated dihalo-monomers for the synthesis of hydrocarbon ionomers. After conventional monomer sulfonation, excess sulfuric acid is quantitatively removed by neutralization with BaCO₃. This leads to the precipitation of excess H₂SO₄ as insoluble BaSO₄, which is easily separated from the sulfonated monomers in their soluble Ba-forms by filtration. Compared to conventional methods, the proposed approach leads to higher yields, drastically reduces the number of purification steps, and can easily be expanded to the preparation of other sulfonated monomers. The specific monomers presented here are suitable for the preparation of sulfonated polyarylenes and sulfonated polyphenylenes.

Three series of spiropyran photoswitches with an auxiliary chiral centre at position 3′ of the indoline unit were synthesized. Using one example, a novel methodology for synthesis of an optically active spiropyran photoswitch with a defined chirality at position 3′ is demonstrated. Furthermore, a new acid-mediated strategy for spiropyran purification affording moderate to excellent yields (up to 96%) is reported herein. Relative diastereomeric ratios of the prepared spiropyrans were evaluated using NMR spectroscopy in five different solvents (syn : anti up to 21 : 79) and their photoswitching properties determined by UV-vis spectroscopy. It was found that substitution at position 8 of the chromene subunit notably accelerates the photoswitching process.

Biguanide-based cationic polyelectrolytes are used as key components of interpolyelectrolyte complexes bolstering alginate hydrogel microcapsules employed in cell therapies. Nevertheless, electrostatic complexation of these unique polycations has not been studied before. In this study, the interaction between biguanide condensates and anionic polyelectrolytes with carboxylate groups was studied on a model system of a metformin condensate (MFC) and an anionic diblock polyelectrolyte poly(methacrylic acid)-block-poly(ethylene oxide) (PMAA-PEO). The formation of MFC/PMAA-PEO core-corona nanoparticles was followed by static, dynamic and electrophoretic light scattering and by isothermal titration calorimetry and their internal structure was investigated by small angle neutron scattering and cryogenic transmission electron microscopy. It was found that the aggregation of PMAA-PEO chains induced by MFC occurred at much lower MFC/PMAA-PEO ratios that would correspond to the isoelectric point, thus yielding strongly negatively charged nanoparticles, suggesting the role of specific (non-electrostatic) interactions in the stabilization of the complex between PMAA and MFC.

In this study, we deployed green Melilotus officinalis extract (MOE) as a corrosion inhibitor for copper. The anticorrosion properties of MOE for Cu in 1 M HNO₃ were investigated by various experimental and numerical techniques, including potentiodynamic polarization (PDP), electrochemical impedance spectroscopy (EIS), and a weight loss (WL) method at different temperatures. Additionally, scanning electron microscopy (SEM) coupled with energy-dispersive X-ray analysis (EDX) and atomic force microscopy (AFM) were utilized to examine the surface morphology of Cu with and without the extract. By contrasting the inhibition effectiveness with and without the extract, the inhibition efficiency (% IE) was observed. The WL method revealed that 300 ppm of the extract had an IE of 93.8% for Cu immersed in one molar HNO₃ solution. The MOE was classified as a mixed type according to the PDP study since it delayed both cathodic and anodic processes, with a cathodic predominance. At 25–45 °C, MOE's free adsorption energies were 23.1–21.5 kJ mol⁻¹, showing that mixed-type adsorption occurred on the Cu surface. Additionally, the Langmuir adsorption isotherm and the adsorption data from the WL tests of MOE showed a good match. The extract could adsorb spontaneously onto the metal surface, according to the thermodynamic conditions. Analysis of the corrosion product using different techniques revealed that a protective layer had formed on the metal's surface. Hence, MOE had a good corrosive inhibitive effect on Cu in HNO₃ solution. It turned out that all the methods used gave consistent results.