Solubility Enhancement of Atrazine by Complexation with Cyclosophoraose Isolated from Rhizobium leguminosarum biovar trifolii TA-1

Coinoculation of arbuscular mycorrhizal fungi and rhizobia stimulates atrazine dissipation by changing the atrazine-degrading bacterial community at the soil aggregate scale

As a potential low-cost and environmentally friendly strategy, bioremediation of herbicide polluted soil has attracted increasing attention. However, there is a lack of knowledge regarding the response of the atrazine-degrading bacterial community to coinoculation of arbuscular mycorrhizal (AM) fungi and rhizobia for atrazine dissipation. In this study, a pot experiment was conducted with AM fungi Glomus mosseae (AM), rhizobia Rhizobium trifolii TA-1 (R) and their coinoculation (AMR) with atrazine. In each treatment, the atrazine-degrading bacterial community of four soil size aggregates, namely large macroaggregates (LMa), small macroaggregates (SMa), microaggregates (Mia) and primary particles (P) were investigated. The results showed that the atrazine residue concentration was lowest in AMR, and that in LMa was also significantly lower than that in the other smaller aggregate sizes. Overall, inoculation, the aggregate fraction and their interaction had significant effects on soil TN, SOC, AP and pH. For the atrazine-degrading bacterial community, the Chao1 index increased with decreasing particle size, but the Shannon index decreased. Moreover, the abundances of the dominant atrazine-degrading bacterial genera Arthrobacter, Bacillus, Marmoricola and Nocardioides in the Mia and P particle size groups were greater than those in the LMa and SMa groups in each treatment. The bacterial communities in the Mia and P particle sizes in each treatment group were more complex. Therefore, coinoculation of AM fungi and rhizobia stimulated atrazine dissipation by changing the atrazine-degrading bacterial community, and the response of the atrazine-degrading bacterial community to each aggregate size varied depending on its distinct soil physicochemical properties.

Changes of atrazine dissipation and microbial community under coexistence of graphene oxide in river water

The coexistence of herbicide atrazine (ATZ) and the nanomaterial graphene oxide (GO) in natural water bodies will be an inevitable scenario due to their widespread application and consequent release into aquatic ecosystems. But the dissipation of ATZ with GO and the response of the microbial community to their combination are still not clear. Here, we investigated the dissipation dynamics and transformation of ATZ with and without GO in river water after 21-d incubation. In the presence of GO, ATZ residue significantly decreased by 11%-43%; the transformation of ATZ markedly increased by 11%-17% when ATZ concentrations were not above 1.0 mg∙L-1. The direct adsorption of ATZ on GO, mainly via π-π interactions, proton transfer and hydrogen bonding, contributed 54%-68% of the total increased ATZ dissipation by GO. ATZ and ATZ+GO exerted effects of similar magnitude on microbial OTU numbers with an increase of bacterial diversity. The coexisting GO increased the relative abundance of ATZ-degradation bacteria and Chitinophagales, thus improving ATZ transformation. This work indicated that the coexistence of GO at environmentally relevant concentrations can effectively reduce ATZ residues and promote the transformation of ATZ to degradation products in river water; nevertheless, the potential risk of GO acting as an ATZ carrier should be given more prominence.

Mechanism of cyclic β-glucan export by ABC transporter Cgt of Brucella

Polysaccharides play critical roles in bacteria, including the formation of protective capsules and biofilms and establishing specific host cell interactions. Their transport across membranes is often mediated by ATP-binding cassette (ABC) transporters, which utilize ATP to translocate diverse molecules. Cyclic β-glucans (CβGs) are critical for host interaction of the Rhizobiales, including the zoonotic pathogen Brucella. CβGs are exported into the periplasmic space by the cyclic glucan transporter (Cgt). The interaction of an ABC transporter with a polysaccharide substrate has not been visualized so far. Here we use single-particle cryoelectron microscopy to elucidate the structures of Cgt from Brucella abortus in four conformational states. The substrate-bound structure reveals an unusual binding pocket at the height of the cytoplasmic leaflet, whereas ADP-vanadate models hint at an alternative mechanism of substrate release. Our work provides insights into the translocation of large, heterogeneous substrates and sheds light on protein-polysaccharide interactions in general.

Organic-Molecule-Based Fluorescent Chemosensor for Nerve Agents and Organophosphorus Pesticides

Organophosphorus (OP) compounds are typically a broad class of compounds that possess various uses such as insecticides, pesticides, etc. One of the most evil utilizations of these compounds is as chemical warfare agents, which pose a greater threat than biological weapons because of their ease of access. OP compounds are highly toxic compounds that cause irreversible inhibition of enzyme acetylcholinesterase, which is essential for hydrolysis of neurotransmitter acetylcholine, leading to series of neurological disorders and even death. Due to the extensive use of these organophosphorus compounds in agriculture, there is an increase in the environmental burden of these toxic chemicals, with severe environmental consequences. Hence, the rapid and sensitive, selective, real-time detection of OP compounds is very much required in terms of environmental protection, health, and survival. Several techniques have been developed over a few decades to easily detect them, but still, numerous challenges and problems remain to be solved. Major advancement has been observed in the development of sensors using the spectroscopic technique over recent years because of the advantages offered over other techniques, which we focus on in the presented review.

Analytical and in silico study of the inclusion complexes between tropane alkaloids atropine and scopolamine with cyclodextrins

Datura stramonium L. (Solanaceae) possesses a rich tropane alkaloids (TAs) spectrum. The plant contains, in particular, the allelopathic compounds scopolamine and atropine, which are poorly soluble in water, thus limiting their use in agrochemical formulations as biocidal and deterrent agents against herbivore insects. The efficacy of the hydrophobic TAs extracts could be increased with the improvement of their dissolution/leaching properties. This is important for improving screening and test performance and for elucidating the activity of environmentally friendly agricultural approaches, with new perspectives for the production and use of those biodegradable insecticidal products. The present study explores the aspects of atropine and scopolamine complexation with cyclodextrin (CDs) through FT-IR and UV–Vis spectroscopies. In addition, the structures of the inclusion complex of atropine, scopolamine and β-CD have been investigated by molecular modeling techniques. The results obtained indicate that β-CDs are a promising carriers for improving the properties of TAs, therefore increasing their application potential in agrochemical formulations.

Graphic abstract

Recent progress in development and applications of second near-infrared (NIR-II) nanoprobes

Optical probes for near-infrared (NIR) light have clear advantages over UV/VIS-based optical probes, such as their low levels of interfering auto-fluorescence and high tissue penetration. The second NIR (NIR-II) window (1000-1350 nm) offers better light penetration, lower background signal, higher safety limit, and higher maximum permitted exposure than the first NIR (NIR-I) window (650-950 nm). Therefore, NIR-II laser-based photoacoustic (PA) and fluorescence (FL) imaging can offer higher sensitivity and penetration depth than was previously available, and deeper lesions can be treated in vivo by photothermal therapy (PTT) and photodynamic therapy (PDT) with an NIR-II laser than with an NIR-I laser. Advances in creation of novel nanomaterials have increased options for improving light-induced bioimaging and treatment. Nanotechnology can provide advantages such as good disease targeting ability and relatively long circulation times to supplement the advantages of optical technologies. In this review, we present recent progress in development and applications of NIR-II light-based nanoplatforms for FL, PA, image-guided surgery, PDT, and PTT. We also discuss recent advances in smart NIR-II nanoprobes that can respond to stimuli in the tumor microenvironment and inflamed sites. Finally, we consider the challenges involved in using NIR-II nanomedicine for effective diagnosis and treatment.

Enhancing the Solubility of Curcumin Using a Solid Dispersion System with Hydroxypropyl-β-Cyclodextrin Prepared by Grinding, Freeze-Drying, and Common Solvent Evaporation Methods

Cyclodextrins (CDs) and their derivatives significantly increase drug solubility by forming drug/CD complexes known as solid dispersions (SDs), which consist of an inclusion complex (IC), where the drug is entrapped within the CD cavity, and a non-IC. Here, the SDs of curcumin (CUR) and hydroxypropyl-β-cyclodextrin (HPβCD) were prepared using the grinding, freeze-drying (FD), and common solvent evaporation (CSE) methods and were physicochemically characterized using solubility, powder X-ray diffraction, Fourier transform infrared, differential scanning calorimetry, and dissolution studies. The second or higher order complex of CUR-HPβCD indicated the co-existence of ICs and non-ICs known as the SD system. When comparing the soluble drug amount with CUR crystals, the solubility of SDs was enhanced by up to 299-, 180-, and 489-fold, corresponding to the ground mixtures (GMs), freeze-drying mixtures (FDs), and common solvent evaporation mixtures (CSEs), respectively. The total transformation into the amorphous phase of CUR was observed in GMs and in CSE12, CSE14, and CSE18. The drug was well dispersed within HPβCD in GMs and CSEs, suggesting the formation of hydrogen bonds between CUR and HPβCD, whereas the dispersed behavior of FDs was similar to that of physical mixtures. In SDs, the melting temperature of CUR was in an increased order of CUR in 1:2 ICs, CUR in 1:1 ICs, and CUR crystals. The dissolution rate of CUR was positively improved as the amount of HPβCD in SDs increased. The SD system consisting of CUR and HPβCD significantly increased the drug solubility compared to ICs.

Structural Characterization of Glycerophosphorylated and Succinylated Cyclic β-(1→2)-d-Glucan Produced by Sinorhizobium mliloti 1021

Rhizobia produces different types of surface polysaccharides. Among them, cyclic β-(1→2)-d-glucan is located in the periplasmic space of rhizobia and plays an important role in the adaptation of bacteria to osmotic adaptation. Cyclic β-(1→2)-d-glucan (CG), synthesized from Sinorhiozbbium meliloti 1021, has a neutral and anionic form. In the present study, we characterized the exact chemical structures of anionic CG after purification using size exclusion s (Bio-Gel P-6 and P-2) chromatography, and DEAE-Sephadex anion exchange chromatography. The exact structure of each isolated anionic CG was characterized using various analytical methods such as nuclear magnetic resonance (NMR), attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy and matrix associated laser desorption ionization-time of Flight (MALDI-TOF) mass spectrometry. The precise chemical structures of novel anionic CG molecules were elucidated by various NMR spectroscopic analyses, including ¹H, ¹³C, ³¹P, and 2D HSQC NMR spectroscopy. As a result, we discovered that anionic CG molecules have either glycerophosphoryl or succinyl residues at C6 positions of a neutral CG. In addition, the results of MALDI-TOF mass spectrometric analysis confirmed that there are two types of patterns for anionic CG peaks, where one type of peak was the succinylated CG (SCG) and the other was glycerophospholated CG (GCG). In addition, it was revealed that each anionic CG has one to four substituents of the succinyl group of SCG and glycerophosphoryl group of GCG, respectively. Anionic CG could have potential as a cyclic polysaccharide for drug delivery systems and a chiral separator based on the complexation with basic target molecules.