RSC Advances

Jiao, Chunpeng; Liu, Yuanyuan; Lu, Wenjuan; Zhang, Pingping; Ma, Xia; Wang, Yanfeng

doi: 10.1039/c9ra06174fpmid: 35527965

Hypochlorous acid (HOCl), one of the most reactive and deleterious reactive oxygen species (ROS), plays a vital role in many pathological and physiological processes. However, as a result of the highly reactive and diffusible nature of HOCl, its uncontrolled production may lead to an adverse effect on host physiology. Because of its biological importance, many efforts have been focused on developing selective fluorescent probes to image HOCl. However, it is still challenging to design a fluorescent probe with exclusive selectivity towards HOCl. In this study, a novel fluorescent probe for HOCl, Probe 1 was rationally designed based on 1,8-naphthalimide. As the concentration of HOCl increased, the fluorescence intensity of the probe gradually decreased, and the solution color changed from yellow-green to colorless, indicating this is a “naked-eye sensor”. Probe 1 has a large Stokes shift (120 nm), which can effectively avoid fluorescence self-absorption. In addition, Probe 1 shows excellent selectivity to HOCl among different ions including common ROS, high sensitivity, fast response (<2 min), high fluorescence quantum yield (Φ = 0.93) and low detection limit (0.237 μM). Finally, the imaging results in HeLa cells showed that the probe could be used for the detection of exogenous and endogenous HOCl, and proved the potential of the probe as a biosensor for the detection of HOCl.

Akato, Kokouvi M.; Nguyen, Ngoc A.; Rajan, Kalavathy; Harper, David P.; Naskar, Amit K.

doi: 10.1039/c9ra07052dpmid: 35527949

In this report we describe repurposing of recycled polyesters as a matrix for lignin-a biorefinery coproduct that is used as a solid fuel and needs to find higher value-to make sustainable high-performance thermoplastic materials. Brittle lignin oligomers, isolated from plant biomass, require a low-melting host polymer matrix to form a rigid and tough renewable material. We demonstrate controlled lignin dispersion and interfacial interactions in softened recycled polyethylene terephthalate (PET) using a simple solvent-free, melt-blending technique. To avoid lignin degradation and devolatilization during melt processing, it was thermally treated. Tall oil fatty acid was used to enable PET processability at low enough temperature to accommodate lignin without charring. Chemical analysis reveals reduction of aliphatic hydroxyl content from 2 mmol g−1 to 1.63 mmol g−1 and an increase of total phenolic hydroxyl moieties from 5.86 to 6.64 mmol g−1 and cleavage of β-O-4 ether linkages due to thermal treatment. Structural transformation of lignin macromolecules during heat treatment was further confirmed by an increase in molar mass and improved thermal stability. Interfacial interactions between lignin and PET were assessed from mechanical properties and thermal analyses. Thermal treatment not only helps to improve the stability of lignin but also slightly reduces the size of the dispersed lignin domains via favored interfacial interactions with the PET matrix. These methods improve mechanical properties of the material. Further, incorporation of lignin in the plasticized PET matrix increases the ductility in the blended products. The method we discuss here utilizes industrial wastes and co-products, and it does not require solvent or toxic chemicals during the reactive extrusion process that yields complete conversion to products.

Chen, Jinyang; Han, Xiaoran; Mei, Lan; Liu, Jinchuan; Du, Kui; Cao, Tuanwu; Li, Qiang

doi: 10.1039/c9ra07361bpmid: 35527951

This study provides a direct, sustainable and eco-friendly method for the synthesis of various sulfonamides via the sulfonylation of sulfonyl hydrazides with tert-amines. The method utilizes sulfonyl hydrazides to oxidize and couple with tertiary amines through selective cleavage of C–N bonds. In this reaction, molecular iodine was used as the catalyst and t-butyl hydroperoxide was used as the oxidant.

Bernauer, Josef; Wu, Guojiao; Jacobi von Wangelin, Axel

doi: 10.1039/c9ra07604bpmid: 35527959

An iron-catalysed allylation of organomagnesium reagents (alkyl, aryl) with simple allyl acetates proceeds under mild conditions (Fe(OAc)2 or Fe(acac)2, Et2O, r.t.) to furnish various alkene and styrene derivatives. Mechanistic studies indicate the operation of a homotopic catalyst. The sequential combination of such iron-catalysed allylation with an iron-catalysed hydrogenation results in overall C(sp3)–C(sp3)-bond formation that constitutes an attractive alternative to challenging direct cross-coupling protocols with alkyl halides.

Yang, Liu Willow; Liu, Chenhui; Yang, Tao

doi: 10.1039/c9ra04121dpmid: 35527964

Anion exchange membranes (AEMs) are adept at extracting sulfate for sulfur isotope analyses by multiple-collector inductively coupled plasma mass spectrometry (MC-ICP-MS) from natural samples typically with low sulfate concentrations. But up to now, their capability for sulfate extraction is still lacking adequate research. In this study, a series of detailed tests on AEMs for sulfate extraction were developed, which included the tolerance of pH, the effect of competitive anions, and the lowest concentration limit of sulfate uploading. The optimal scope of pH for sulfate exchange is from 3 to 11. Approximately over 90% of sulfate recoveries and reliable sulfur isotope analyses can be achieved when the concentrations of nitrate, chloride, phosphate, carbonate, and bicarbonate are limited in 0.5 mmol per L per cm2 of a piece of AEM. In practice, we suggest that the applicable concentrations are able to increase to 10 times, except for phosphate. The lowest uploading concentration of sulfate that can be adsorbed by the AEM without sulfur isotope fractionation is further detected as 0.5 μmol L−1 though the recovery of sulfate decreases when its concentration is lower than 0.01 mmol L−1. This research offers insight into realizing accurate and precise sulfur isotope analyses for natural freshwater and marine pore water by MC-ICP-MS.

Bhugra, Vaibhav Singh; Maddah, Mohsen; Williams, Grant V.; Plank, Natalie; Nann, Thomas

doi: 10.1039/c9ra06470bpmid: 35527952

Diisopropylammonium bromide (DIPAB) doped poly(vinylidene difluoride) (PVDF) nanofibers (5, 10 and 24 wt% DIPAB doping) with improved and tunable dielectric properties were synthesised via electrospinning. DIPAB nanoparticles were grown in situ during the nanofiber formation. X-Ray diffraction (XRD) patterns and Fourier transform infrared spectroscopy (FTIR) proved that electrospinning of DIPAB doped PVDF solutions led to the formation of a highly electro-active β-phase in the nanofibers. Electrospinning in the presence of DIPAB inside PVDF led to very well aligned nanofibers with preferred (001) orientation that further enhanced the effective dipole moments in the nanofiber structures. The dielectric properties of the composite nanofibers were significantly enhanced due to the improved orientation, ionic and interfacial polarisation upon the applied electrospinning process, ionic nature of DIPAB and the interface between the PVDF nanofibers and equally dispersed DIPAB nanoparticles inside them, respectively. The relative dielectric constant of the PVDF nanofibers was improved from 8.5 to 102.5 when nanofibers were doped with 5% of DIPAB. Incorporating DIPAB in PVDF nanofibers has been shown to be an effective way to improve the structural and dielectric properties of PVDF.

Tanbouza, Nour; Keipour, Hoda; Ollevier, Thierry

doi: 10.1039/c9ra07203apmid: 35527937

The insertion reaction of a broad range of diazo compounds into Si–H bonds was found to be efficiently catalysed by Fe(OTf)2 in an emerging green solvent i.e. dimethyl carbonate (DMC). The α-silylated products were obtained in good to excellent yields (up to 95%). Kinetic studies showed that the extrusion of N2 to form an iron carbene intermediate is rate-limiting. The iron-catalysed insertion reaction of methyl α-phenyl-α-diazoacetate into polar X–H bonds (S–H, N–H, and O–H) was also established in DMC.

Park, Jung-Soo; Park, Jong-Hwa; Kim, Ki-Young

doi: 10.1039/c9ra05408apmid: 35527980

Glutamate is an important neurotransmitter in the central nervous system; however, at high concentrations, it causes excitotoxicity and many neurological disorders. Excitotoxicity induces cell death by apoptosis. Thus, factors that can inhibit the apoptotic pathways are a target of drug development for the treatment and prevention of neurodegenerative diseases. Herein, the antioxidative and neuroprotective effects of myristargenol A were examined in glutamate-induced mouse hippocampal neuronal HT22 cells. When the HT22 cells were stressed with glutamate, cell viability decreased to 44.4 ± 5.6% when compared with the case of the control cells (100 ± 4.8%); however, when these cells were treated with myristargenol A (10 μM), the cell viability was increased by 113.6 ± 2.3%. The protective effect of myristargenol A against the apoptosis of glutamate-induced HT22 cells was also confirmed using FITC-annexin V/propidium iodide double staining. In addition, myristargenol A protected the mitochondrial membrane potential (ΔΨm). Subsequently, the expression levels of proteins in the caspase pathway related with the induction of apoptosis were decreased. Moreover, the expression levels of mitochondrial-related proteins, such as Bcl-2 and Bax, were examined, and it was found that the expression ratio of Bax/Bcl-2 decreased. In addition, myristargenol A inhibited the activity of mitogen-activated protein kinases, including p38 and c-Jun N-terminal kinase, for an oxidative stress protection effect but increased the activity of the extracellular signal-regulated kinases 1 and 2 for cell proliferation. These results reveal that myristargenol A possesses a neuroprotective effect against the neuronal cell damage caused by glutamate.

Ren, Huiru; Hao, Jingbiao; Kang, Weimin; Wang, Gang; Ju, Jingge; Li, Lei; Cheng, Bowen

doi: 10.1039/c9ra05681epmid: 35527938

Due to the spunlaced effect, waste spunlaced facial puff has a high degree of fiber entanglement and an abundant three-dimensional (3D) network porous structure, which make it form a 3D carbon framework material more easily after carbonization. For the first time, the monolithic 3D carbon framework is synthesized from waste spunlaced facial puff (WCF) and used as the adsorbent for contaminants in water. The adsorption capacity of WCF for oils and organic reagents can be 34–137 times its own weight. Over five adsorption-harvesting cycles, the adsorption capacity of WCF to organic pollutants can recover up to 95% of its initial capacity. Moreover, WCF exhibits stable permeation flux and high separation efficiency in a water–heavy oil system, which is about 7714 L m−2 h−1 and higher than 99%, respectively. With a combination of waste spunlaced facial puff with monolithic 3D porous structure as a raw material, facile and green preparation process, low density, excellent hydrophobicity and lipophilicity, WCF as an adsorbent has great superiority in removal of organic pollutant solvents and environmental protection as well as other applications, such as energy storage materials, catalyst carriers, electric information, etc. Furthermore, this work would provide a new strategy for recovery use of waste spunlaced cotton materials.

Li, Wei; Tao, Cheng; Wang, Jiexin; Le, Yuan; Zhang, Jianjun

doi: 10.1039/c9ra04343hpmid: 35527962

The complex construction within the oral cavity causes incomplete surgical resection of oral squamous cell carcinoma (OSCC) that may enhance the risk of recurrence and metastasis in the treatment. In situ forming injectable hydrogels with minimally invasive procedures, encapsulation stability and stimuli-responsive degradation have emerged as promising carriers for local drug delivery. In this study, doxorubicin (DOX) was first encapsulated in biodegradable poly(d,l-lactide)-poly(ethylene glycol)-poly(d,l-lactide) (PDLLA-PEG-PDLLA) micelles and then loaded into an in situ injectable hyaluronic acid (HA) hydrogel, which was cross-linked by a matrix metalloproteinase-2 (MMP-2)-responsive peptide (GCRDGPQGIWGQDRCG) through a Michael addition reaction. In vitro studies demonstrated that the HA hydrogel had a sensitive MMP-2-responsive drug release profile. Investigations including MTT, live-dead, apoptosis, and wound healing assays illustrated that DOX micelle-loaded HA hydrogels exhibited outstanding cytotoxicity against squamous carcinoma cells (SCC-15). Furthermore, by in vivo studies, we also proved that HA hydrogels degraded faster in the tumor site than in normal tissue, which led to a local sustained release of DOX-loaded micelles and tumor growth inhibition of oral squamous cell carcinoma (OSCC) without any damage to the organs. Therefore, this work provides a remarkable drug delivery platform for local chemotherapy and other applications.