RSC Advances

Guo, Xin; Xia, Lili; Huang, Jinxin; Wang, Yiming; Gu, Yueqing; Wang, Peng

doi: 10.1039/c8ra01683fpmid: 35539911

Fluorescent probes have been considered to be efficient tools for the visualization of physiological and pathological processes. Herein, a dual-site fluorescence probe denoted as LC-1 was developed for the detection of cysteine (Cys) and its metabolite SO32−. The probe was shown to be highly sensitive to Cys and SO32− with a turn-on mode fluorescence signal through two emission channels under excitations at wavelengths of 320 nm and 440 nm. Notably, the LC-1 probe was also observed to be satisfactorily sensitive to Cys and SO32− in the presence of other amino acids and reactive oxygen species (ROS). Meanwhile, LC-1 was shown to have low cytotoxicity and was successfully applied for imaging the metabolism of Cys in living cells.

Wu, Dong; Liu, Chang; Liu, Yumin; Xu, Zenghui; Yu, Zhongyuan; Yu, Li; Chen, Lei; Ma, Rui; Zhang, Jinqiannan; Ye, Han

doi: 10.1039/c8ra01524dpmid: 35539953

Highly efficient solar absorption is very promising for many practical applications, such as power generation, desalination, wastewater treatment and steam generation. Nevertheless, so far, near-ideal solar thermal energy conversion is still difficult to achieve, which requires a near-perfect absorption from the UV to the near-infrared region and meanwhile a mid-and-far infrared absorption close to zero. Here, by employing FEM and FDTD methods respectively, a nearly omnidirectional ultra-broadband efficient selective solar absorber based on a nanoporous hyperbolic metamaterial (HMM) structure is proposed and numerically demonstrated, which can achieve an extremely high average absorption efficiency above 98.9% within the range of 260–1580 nm. More significantly, in the respect of physical mechanism, the near-perfect solar absorption of this multilayered nanostructures is primarily due to the excitation of magnetic and electric resonances resulting from localized surface plasmon resonance at metal/dielectric interfaces, working completely different from those previously reported tapered multilayered absorbers associated with the slow-light effect. Besides, for retaining heat, a low emissivity is realized in mid-infrared region, causing a near-ideal total solar-thermal conversion efficiency up to 90.32% at 373.15 K (ηideal = 95.6%), which is particularly useful in solar steam generation. Detailed studies are also performed for higher operating temperatures, which indicates efficient solar thermal conversions also can be well maintained by tuning geometric parameters at higher temperatures. Taking into consideration of the practical application, even with ±60 degrees angle of incidence, average absorptivity higher than 90% can be still obtained in the whole solar spectrum at both TE and TM polarization. The near-perfect absorption, wide angle, polarization independence, spectral selectivity and high tunability make this solar absorber promising for practical applications in solar energy harvesting.

Shen, Shi-gang; Jia, Shi-ru; Yan, Rong-rong; Wu, Yi-kai; Wang, Hui-yan; Lin, Ya-hui; Zhao, Dong-xue; Tan, Zhi-lei; Lv, He-xin; Han, Pei-pei

doi: 10.1039/c8ra04024apmid: 35539925

Nostoc flagelliforme is a pioneer organism in the desert and exerts important ecological functions. The habitats of N. flagelliforme are characterized by intense solar radiation, while the ultraviolet B (UV-B) tolerance has not been fully explored yet. To evaluate the physiological responses of N. flagelliforme to UV-B radiation, three intensities (1 W m−2, 3 W m−2 and 5 W m−2) were used, and the changes in photosynthetic pigments, cell morphology, mycosporine-like amino acids (MAAs) synthesis and cell metabolism were comparatively investigated. Under high UV-B intensity or long term radiation, chlorophyll a, allophycocyanin and phycocyanin were greatly decreased; scanning electron microscope observations showed that cell morphology significantly changed. To reduce the damage, cells synthesized a large amount of carotenoid. Moreover, three kinds of MAAs were identified, and their concentrations varied with the changes of UV-B intensity. Under 1 W m−2 radiation, cells synthesized shinorine and porphyra-334 against UV-B, while with the increase of intensity, more shinorine turned into asterine-330. Metabolite profiling revealed the contents of some cytoprotective metabolites were greatly increased under 5 W m−2 radiation. The principal component analysis showed cells exposed to UV-B were metabolically distinct from the control sample, and the influence on metabolism was particularly dependent on intensity. The results would improve the understanding of physiological responses of N. flagelliforme to UV-B radiation and provide an important theoretical basis for applying this organism to control desertification.

Chen, Li-Li; Cui, Hui-Fang; Fan, Shuang-Fei; Li, Zong-Yi; Han, Shuang-Yin; Ma, Xin; Luo, Shu-Wen; Song, Xiaojie; Lv, Qi-Yan

doi: 10.1039/c8ra03134gpmid: 35539942

Noninvasive diagnosis of Helicobacter pylori (H. pylori) infection is very attractive. This study investigated the single strand DNA (ssDNA) acquisition method from H. pylori in dental plaque, and the integration of our previously developed 43-mer H. pylori DNA biosensor with the obtained target ssDNA (tDNA). Dental plaque samples were collected from 34 patients/volunteers, whose gastric H. pylori infection statuses were tested with the 13C urea breath test (UBT). The samples were treated with colony polymerase chain reaction (PCR) to obtain double strand DNA (dsDNA) of 104 basepairs (bp) long. A blocker ssDNA was designed and used in thermal treatment of the dsDNA to release the 104-mer tDNA, which contains the 43-mer DNA sequence in the middle. PCR primers were designed, and the tDNA releasing and detection conditions with the biosensor were optimized. The limit of detection with the biosensor was 12 fM dsDNA. The dental plaque detection results correlated quite well with the UBT results, with a sensitivity of 100%, and specificity of 97%. These results indicate that the residence of H. pylori in dental plaque is highly associated with gastric H. pylori infection, and detection of dental plaque samples with our DNA biosensor is promisingly applicable in noninvasive diagnosis of H. pylori infection.

Zhang, D.; Liu, X. Y.; Zhao, H. T.; Yang, L.; Lü, T.; Jin, M. Q.

doi: 10.1039/c8ra04013cpmid: 35539934

Radioactive iodine is quite mobile in soil and poses threats to human health and the ecosystem. Many materials, including layered double hydroxides (LDH), have been synthesized to successfully capture iodine from aqueous environments. However, limited information is available on the application of LDH in soil to immobilize iodine species. In the present study, the feasibility of using Mg–Al–NO3 LDH for retention of soil iodate (IO3−) in both batch and column systems was analyzed. The 2 : 1 Mg–Al–NO3 LDH exhibited the greatest removal efficiency of IO3− from aqueous solution, compared with 3 : 1 and 4 : 1 Mg–Al–NO3 LDH. The Mg2–Al–NO3 LDH demonstrated a strong affinity for IO3−, with a high sorption capacity of 149 528 mg kg−1 and a Freundlich affinity constant KF of 21 380 L kg−1. The addition of Mg2–Al–NO3 LDH in soil resulted in significant retention of IO3− in both the batch and column experiments. The affinity parameter KF of soil with the addition of 1.33% Mg2–Al–NO3 LDH was 136 L kg−1, which was 28.6 times higher than soil without LDH added. Moreover, the eluted iodate percentage was only 12.9% in the soil column with the 1.33% Mg2–Al–NO3 LDH addition, whereas almost 43.5% iodate was washed out in the soil column without LDH addition. The results suggested that Mg2–Al–NO3 LDH could effectively immobilize iodate in soil without obvious interference.

Perfecto-Irigaray, Maite; Albo, Jonathan; Beobide, Garikoitz; Castillo, Oscar; Irabien, Angel; Pérez-Yáñez, Sonia

doi: 10.1039/c8ra02676apmid: 35539929

Herein we report the solventless synthesis and doping of the benchmark HKUST-1(Cu) as a facile route to afford heterometallic metal–organic frameworks (MOFs) having proficient behavior as electrocatalytic materials in the reduction of carbon dioxide. Zn(ii), Ru(iii) and Pd(ii) were selected as doping metals (MD) with the aim of partially replacing the Cu(ii) atoms of the pristine structure to afford HKUST-1(Cu,MD) type materials. Apart from the high yield and good crystallinity of the obtained materials, the extremely high reagent concentration that the reaction conditions imply makes it feasible to control dopant loading in all cases. Prepared samples were processed as electrodes and assembled in a continuous flow filter-press electrochemical cell. Faraday efficiency to methanol and ethanol at Ru(iii)-based electrodes resulted in activity as high as 47.2%, although the activity of the material decayed with time. The interplay of the dopant metal and copper(ii), and the long-term performance are also discussed.

Umasekhar, Booruga; Shetti, Vijayendra S.; Ravikanth, Mangalampalli

doi: 10.1039/c8ra03669apmid: 35539959

Corroles are 18 π aromatic macrocyclic systems having one direct pyrrole–pyrrole linkage leading to a contracted cavity compared to porphyrins. Corroles exhibit contrasting coordination chemistry and properties compared to porphyrins. Structural modification of corroles by introducing a heteroatom in their aromatic conjugation circuit i.e., either in the core or at a meso position leads to a new class of corrinoids called heterocorroles. The core modification strategy includes replacing one or two core nitrogen atom(s) with O, S or C atoms and meso-modification involves replacing the meso-carbon atom at the 10-position with NH, NR, O, S, Se or Si atoms. This review article presents an overview of the progress in heterocorrole chemistry including their syntheses, key structural aspects and properties.

Huang, Jen-Huang; Haffey, Kiersten; Arefin, Ayesha; Akhadov, Leyla E.; Harris, Jennifer F.; Iyer, Rashi; Nath, Pulak

doi: 10.1039/c8ra01256cpmid: 35539930

Thin and flexible elastomeric membranes are frequently used in many microfluidic applications including microfluidic valves and organs-on-a-chip. The elastic properties of these membranes play an important role in the design of such microfluidic devices. Bulge testing, which is a common method to characterize the elastic behavior of these membranes, involves direct observation of the changes in the bulge height in response to a range of applied pressures. Here, we report a microfluidic approach to measure the bulging height of elastic membranes to replace direct observation of the bulge height under a microscope. Bulging height is measured by tracking the displacement of a fluid inside a microfluidic channel, where the fluid in the channel was designed to be directly in contact with the elastomeric membrane. Polydimethylsiloxane (PDMS) and polyurethane (PU) membranes with thickness 12–35 μm were fabricated by spin coating for bulge testing using both direct optical observation and the microfluidic method. Bulging height determined from the optical method was subject to interpretation by the user, whereas the microfluidic approach provided a simple but sensitive method for determining the bulging height of membranes down to a few micrometers. This work validates the proof of principle that uses microfluidics to accurately measure bulging height in conventional bulge testing for polydimethylsiloxane (PDMS) and polyurethane (PU)eElastomeric membranes.

Zhang, Hao; Ma, Jie; Shen, Jie; Lan, Yan; Ding, Lili; Qian, Shulou; Xia, Weidong; Cheng, Cheng; Chu, Paul K.

doi: 10.1039/c8ra01882kpmid: 35539941

Although plasma sterilization has attracted much attention, the underlying mechanisms and biochemical pathways are still not fully understood. In this work, we investigate the molecular mechanism pertaining to the inactivation of Escherichia coli (E. coli) by air discharge plasmas. The membrane protein YgaP and intracellular protein swc7 are over-expressed in E. coli by genetic recombination and gene inducible expression techniques and plasma exposure is demonstrated to alter the structures of YgaP and swc7 in E. coli. The plasma-induced damage of YgaP and swc7 involves changes in the secondary and tertiary structures instead of the primary structure and the modification effectiveness depends on the storage time after the plasma treatment. Owing to the unique structure of E. coli, YgaP is more susceptible to the plasma treatment than intracellular swc7. Within 1 h after plasma exposure, YgaP is modified but not swc7, but after 1 h or longer, both YgaP and swc7 proteins are indeed modified. By analyzing the plasma-induced antimicrobial efficacy and modification of YgaP and swc7, plasma-induced modification of the membrane proteins is the major cause of bacterial death but there is no identifiable relationship with modification of the intracellular protein. The new results provide insights into the mechanism of multiple plasma-induced damage to bacteria and cells as well as the disinfection mechanism.

Wei, Wenjing; Wang, Weihua; Xu, Kaining; Feng, Wenling; Li, Xiaoping; Li, Ping

doi: 10.1039/c8ra03046dpmid: 35539902

To explore the potential role of the methylidyne radical (CH) in the transformation of 2,3,7,8-tetrachlorodibenzofuran (TCDF), in this study, the detailed reaction mechanisms between TCDF and CH radical have been systematically investigated employing the B3LYP method of density functional theory (DFT) in combination with the atoms in molecules (AIM) theory and ab initio molecular dynamics. It was found that the title reaction is a multi-channel reaction, i.e., the CH radical can attack the C–X (X = C, Cl, H, O) bonds of TCDF via the insertion modes, resulting in the formation of 13 products. Thermodynamically, the whole reaction processes are exothermic and spontaneous since all the enthalpy and Gibbs free energy changes are negative values in the formation processes. Moreover, the thermodynamic stability of the products is controlled by the distribution of the single unpaired electron. Kinetically, the most favorable reaction channel is the insertion of the CH radical into the C–C bond except for the C atoms attached to the chlorine atom. Moreover, the dominant products have been further confirmed by the molecular dynamics. Meanwhile, the IR spectra and hyperfine coupling constants of the dominant products have been investigated to provide helpful information for their identification experimentally. In addition, the reactivity of the CH radical toward the F- and Br-substituted TCDFs has also been investigated. Expectedly, the present findings can enable us to better understand the reactivity of the CH radical toward organic pollutants analogous to TCDF in the atmosphere.