Aqueous Solution Research Articles

An Artificial Light-Harvesting System based on Supramolecular AIEgen Assembly.

Photosynthesis is a complex multi-step process in which light collection is the initial step of photosynthesis and plays an important role in the efficiency of solar energy utilization. In order to improve the utilization of sunlight, researchers have developed a variety of artificial light-harvesting system to simulate photosynthesis in nature. Here, we report a supramolecular self-assembly artificial light-harvesting system in aqueous solution. We modified β-CD with the donor molecule naphthalimide and adamantane with the tetraphenylethylene molecule which has aggregation-induced emission effects (AIE). By using fluorescent molecules with AIE, the self-quenching effect caused by aggregation in aqueous solution can be effectively avoided. Due to the host-guest interaction of β-CD and adamantane, nanoparticles with stable structure and uniform size can be spontaneously assembled in water. Because of the close distance and strong spectral overlap between naphthalimide and tetraphenylethylene, Förster resonance energy transfer (FRET) was realized, and artificial light-harvesting system was successfully constructed in aqueous solution. The light-harvesting system has a high energy transfer efficiency (ΦET). Therefore, this study provides a new strategy for constructing artificial light-harvesting system.

Reaction-Induced Self-Assembly of Polymyxin Mitigates Cytotoxicity and Reverses Drug Resistance.

Polymyxins have been regarded as an efficient therapeutic against many life-threatening, multidrug resistant Gram-negative bacterial infections; however, the cytotoxicity and emergence of drug resistance associated with polymyxins have greatly hindered their clinical potential. Herein, the reaction-induced self-assembly (RISA) of polymyxins and natural aldehydes in aqueous solution is presented. The resulting assemblies effectively mask the positively charged nature of polymyxins, reducing their cytotoxicity. Moreover, the representative PMBA4 (composed of polymyxin B (PMB) and (E)-2-heptenal (A4)) assemblies demonstrate enhanced binding to Gram-negative bacterial outer membranes and exhibit multiple antimicrobial mechanisms, including increased membrane permeability, elevated bacterial metabolism, suppression of quorum sensing, reduced ATP synthesis, and potential reduction of bacterial drug resistance. Remarkably, PMBA4 assemblies reverse drug resistance in clinically isolated drug-resistant strains of Gram-negative bacteria, demonstrating exceptional efficacy in preventing and eradicating bacterial biofilms. PMBA4 assemblies efficiently eradicate Gram-negative bacterial biofilm infections in vivo and alleviate inflammatory response. This RISA strategy offers a practical and clinically applicable approach to minimize side effects, reverse drug resistance, and prevent the emergence of resistance associated with free polymyxins.

Designing Fast-Moving Antibacterial Microtorpedoes to Treat Lethal Bacterial Biofilm Infections.

Engineering fast-moving microrobot swarms that can physically disassemble bacterial biofilms and kill the bacteria released from the biofilms is a promising way to combat bacterial biofilm infections. Here, we report electrochemical design of Ag7O8NO3 microtorpedoes with outstanding antibacterial performance and meanwhile capable of moving at speeds of hundreds of body lengths per second in clinically used H2O2 aqueous solutions. These fast-moving antibacterial Ag7O8NO3 microtorpedoes could penetrate into and disintegrate the bacterial biofilms and, in turn, kill the bacteria released from the biofilms. Based on the understanding of the growth behavior of the microtorpedoes, we could fine-tune the morphology of the microtorpedoes to accelerate the moving speed and increase their penetration depth into the biofilms simply via controlling the potential waveforms. We further developed an automatic shaking method to selectively peel off the uniformly structured microtorpedoes from the electrode surface, realizing continuous electrochemical production of the microtorpedoes. Animal experiments proved that the microtorpedo swarms greatly increased the survival rate of the mice infected by lethal biofilms to >90%. We used the electrochemical method to design and massively produce uniformly structured fast-moving antibacterial microtorpedo swarms with application potentials in treatment of lethal bacterial biofilm infections.

A stable and regenerative TiO2/Bi2MoO6 photocatalyst for highly effective degradation of Rhodamine B and Congo Red

ABSTRACT This research unravels a facile method for synthesising TiO2/Bi2MoO6 photocatalysts and their effective applications in degrading industrial dyes. Initially, Bi2MoO6 was prepared as the substrate, followed by the addition of TiO2 to form the TiO2/Bi2MoO6 composite. The photocatalyst was characterised by powder X-ray diffraction (XRD), scanning electron microscopy with energy-dispersive X-ray spectrometry (SEM-EDS), X-ray photoelectron spectroscopy (XPS), high-resolution transmission electron microscopy (HR-TEM), photoluminescence (PL), and UV-Vis diffuse reflectance spectroscopy (UV-Vis DRS). Its photocatalytic properties were evaluated by dye degradation under various conditions, including different dopant loading amounts, the reaction time, the initial concentration of the dye, and pH values. The results indicated that 50 mg of 15% TiO2/Bi2MoO6 achieved the highest photodegradation efficiency: 98.51% for 50 mL 10 mg L−1 Rhodamine B (RhB) within 100 min in a neutral buffer solution and 90.71% for 50 mL 10 mg L−1 Congo Red (CR) within 80 min in an aqueous solution. This material exerted effectiveness across a wide pH range, with removal rates of RhB exceeding 95.41% in both acidic and alkaline conditions. The degradation process conformed to the pseudo-first-order kinetic model. Radical trapping experiments revealed that the dye degradation mechanism involved ∙ O 2 − and h+. Notably, the synthesised TiO2/Bi2MoO6 photocatalyst demonstrated high stability and reusability, maintaining performance even after four degradation cycles. The TiO2/Bi2MoO6 photocatalyst, with TiO2 as the dopant and Bi2MoO6 as the substrate, demonstrated significant versatility and potential for practical dye degradation applications.

Highly selective methanol adsorption from dilute aqueous solutions using Mn3[Fe(CN)6]2: a Prussian blue analog.

Mn3[Fe(CN)6]2 (MnHCF) selectively adsorbs methanol from water with a distribution coefficient of 11 mL g-1, which is 3-11 times that of activated carbons and zeolites. MnHCF exhibits an adsorption capacity of 0.36 mmol g-1 and can adsorb 1000 mg MeOH per L in aqueous solution, demonstrating its effectiveness for treating methanol-contaminated wastewater.

Experimental study of methylene blue adsorption from aqueous solutions onto natural Algerian goethite

Experimental study of methylene blue adsorption from aqueous solutions onto natural Algerian goethite

Learning a reactive potential for silica-water through uncertainty attribution

The reactivity of silicates in aqueous solution is relevant to various chemistries ranging from silicate minerals in geology, to the C-S-H phase in cement, nanoporous zeolite catalysts, or highly porous precipitated silica. While simulations of chemical reactions can provide insight at the molecular level, balancing accuracy and scale in reactive simulations in the condensed phase is a challenge. Here, we demonstrate how a machine-learning reactive interatomic potential trained on PaiNN architecture can accurately capture silicate-water reactivity. The model was trained on a dataset comprising 400,000 energies and forces of molecular clusters at the ωB97X-D3/def2-TZVP level. To ensure the robustness of the model, we introduce a general active learning strategy based on the attribution of the model uncertainty, that automatically isolates uncertain regions of bulk simulations to be calculated as small-sized clusters. The potential reproduces static and dynamic properties of liquid water and solid crystalline silicates, despite having been trained exclusively on cluster data. Furthermore, we utilize enhanced sampling simulations to recover the self-ionization reactivity of water accurately, and the acidity of silicate oligomers, and lastly study the silicate dimerization reaction in a water solution at neutral conditions and find that the reaction occurs through a flanking mechanism.

CeO2-CuO composites prepared via supercritical antisolvent precipitation for photocatalytic hydrogen production from lactic acid aqueous solution

The global increase in energy demand requires a continuous search for renewable and clean alternative resources to fossil fuels. Hydrogen is emerging as a promising energy carrier for the future; its production via photocatalysis, driven by sunlight, can directly convert solar energy into a usable or storable energy resource. However, water splitting requires sacrificial agents or electron donors/hole scavengers, such as short-chain organic acids. This research explores the use of lactic acid as a source for photocatalytic hydrogen production, offering valuable alternatives for wastewater management and renewable energy production. This study employed the innovative supercritical antisolvent (SAS) technique to micronize the precursors of both the active phase (CeO2) and co-catalyst (CuO), ensuring rapid and complete solvent removal and size reduction of photocatalyst precursors. The prepared samples were characterized by field emission scanning electron microscopy (FESEM), Fourier transform infrared (FT-IR) spectroscopy, dynamic light scattering (DLS) analysis, Brunauer-Emmett-Teller (BET) analysis and thermogravimetric analysis (TGA). This study has shown that the micronization process resulted in a notable improvement in CeO2 photocatalytic activity, attributed to the reduction of the dimensions of the powders. Hydrogen production was equal to 3989 μmol L−1 for the SAS-produced photocatalyst while using a commercial CeO2 sample resulted in H2 production of 2519 μmol L−1. The enhanced photoactivity of CeO2-CuO composites was found to be related to the presence of CuO. The optimal CuO amount was equal to 0.5 wt%, determining a hydrogen production of 9313 μmol L−1 after 4 h of UV irradiation time. A photocatalytic test carried out with deuterated water (D2O) instead of distilled H2O demonstrated that hydrogen was preferentially produced from water splitting reaction, whereas lactic acid acted as a sacrificial agent being oxidized from positive holes photogenerated in the valence band of CuO.

Nanomotor-hydrogel Delivery System with Enhanced Antibacterial Performance for Wound Treatment.

In this study, we present a novel system consisting of nanomotors and a hydrogel. Calcium carbonate nanomotors are prepared using layer-by-layer self-assembly technology with calcium carbonate nanoparticles as the core and catalase (CAT) and polydopamine (PDA) as the shell. Calcium carbonate nanomotors were loaded into a Schiff base hydrogel to synthesize the CaCO3@NM-hydrogel system. A nanomotor is a device that works on the nanoscale to convert some form of energy to mechanical energy. The motion speed of the system in 5.0 mM H2O2 aqueous solution under near-infrared light (NIR) irradiation with a power density of 1.8 W/cm2 is 13.6 μm/s. The addition of CaCO3@NM further promotes gelation and improves the mechanical properties. The energy storage modulus increases to 4.0 × 103 Pa, which is 50 times higher. Schiff base hydrogels form dynamic reversible chemical bonds due to inter- and intramolecular hydrogen bonding. They also have good self-healing properties, as observed by measuring the energy storage modulus versus the loss modulus at 1 versus 10 kHz. The results show that the system significantly inhibited the growth of both Gram-positive bacteria, Staphylococcus aureus, and Gram-negative bacteria, Escherichia coli, after 48 h, with an inhibition rate of nearly 95%. These findings provide a basis for further research and potential applications of the system in wound dressings.

On relating quasi-static load threshold K1scc to K1c

Abstract It is common to observe that monotonic K1c (lab air) and K1scc (NaCl solution) decrease with increasing YS of an alloy. K1c is measured in lab air and K1scc in an aqueous solution such as NaCl. It is noted that K1c is not considered as a subcritical parameter while K1scc is. Interestingly, for a given alloy, both these parameters seem to be inter-related. That is, K1scc is linearly related to K1c, such that K1scc increases with increasing K1c. This may indicate that plasticity is affecting the K1scc behavior. This article looks into the conditions that affect K1scc for steels, Al-alloys, and Ti-alloys. This linear variation of K1scc with K1c seems to be independent of alloy YS, E, microstructure, and work hardening rate. This observation seems similar in all three systems of alloys. How these parameters are interrelated is analyzed and discussed in detail.

Sustainable removal of tetracycline and paracetamol from water using magnetic activated carbon derived from pine fruit waste

This work presents highly porous magnetic activated carbon nanoparticles (MPFRC-A) derived from pine fruit residue. The MPFRC-A were produced through a three-step process: physical activation (carbonization temperature: 110–550 °C), chemical activation (H2SO4 (0.1 N, 96%)), and co-precipitation. These nanoparticles were then used to remove tetracycline (TC) and paracetamol (PC) from water. Functionalization with Fe3O4 nanoparticles on the surface of the pine fruit residue-derived activated carbon (PFRC-A) resulted in high saturation magnetization, allowing for separation from aqueous solution using an external magnet. The MPFRC-A adsorbent was characterized by Brunauer–Emmett–Teller (BET) analysis, Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), X-ray diffraction (XRD), and Energy-dispersive X-ray spectroscopy (EDX) analyses, In the experimental section, the effects of various factors on the adsorption process were investigated, including pH, contact time, initial pollutant concentrations, adsorbent dosage, and temperature. Based on these investigations, adsorption isotherm models and kinetics were studied and determined. The results showed that MPFRC-A exhibited a large specific surface area (182.5 m2/g) and a high total pore volume (0.33 cm3/g). The maximum adsorption capacity was achieved at pH 6 and 5 for PC and TC drugs with an adsorbent dose of 400 mg and an initial concentration of 20 mg/L at 25 °C. The study revealed that the experimental data were well-fitted by the Langmuir isotherm model (R2 > 0.98), with maximum uptake capacities of 43.75 mg/g for TC and 41.7 mg/g for PC. Outcomes of the adsorption thermodynamics shows non-spontaneity of the reaction and the adsorption process by all adsorbents was endothermic.

Facile Synthesis of Hemin Derivatives with Modulated Aggregation Behaviour and Enhanced Nitric‐Oxide Scavenging Properties as New Therapeutics for Breast Cancer

Nitric oxide (•NO) plays various pathophysiological roles in breast cancer, significantly influencing the migration of tumour cells through concentration gradients. Therefore, modulating •NO levels via selective scavenging presents a promising approach to treating aggressive •NO‐dependent cancers, such as triple‐negative breast cancer (TNBC). Hemin emerges as a potential scavenger of •NO; however, its metalloporphyrin molecules tend to aggregate in physiological solutions, which limits its biomedical applications. To address this, a modification strategy is employed to minimize aggregation and protect against physiological oxidative degradation while preserving •NO‐scavenging properties. This is achieved through a simple chemical transformation that involves hemin conjugation to aromatic residues, tyrosine, and tyramine via carbodiimide reactions. These derivatives exhibit altered electronic properties and oxidation potential compared to hemin, alongside reduced aggregation tendencies and retained •NO‐binding affinity in aqueous solutions. Furthermore, depending on the type of hemin derivative, there is an associated inhibition of TNBC cell migration. These model hemin compounds demonstrate varying •NO‐binding affinities and resistance levels to oxidative degradation and aggregation, offering insights into the design of •NO‐scavenging molecules with enhanced properties for cancer treatment.

Utilizing a novel green ternary polymeric nanocomposite material to remove tetracycline antibiotic effectively from aqueous solutions

Utilizing a novel green ternary polymeric nanocomposite material to remove tetracycline antibiotic effectively from aqueous solutions

Modeling of textile dye removal from aqueous solution with a Zr-MOF framework : design of experiments and artificial neural network approaches

Modeling of textile dye removal from aqueous solution with a Zr-MOF framework : design of experiments and artificial neural network approaches

Adsorption of cadmium (II) on organic xerogel microspheres: effect of adding sepiolite or vermiculite and operating conditions on the adsorption capacity.

The organic xerogel (OX) was synthesized through sol-gel polymerization of formaldehyde and resorcinol in inverse emulsion using Na2CO3 as a catalyst. Meanwhile, OX containing sepiolite (OX-Sep) and vermiculite (OX-Ver) were prepared similarly to OX but adding clays during synthesis. All materials were mesoporous and presented spherical morphology, and the surface of these materials exhibited an acidic character because the concentration of acidic sites was higher than those of basic sites. Cd(II) adsorption from aqueous solutions onto OX, OX-Sep, and OX-Ver was examined, and the OX-Sep showed the highest adsorption capacity towards Cd(II) of 189.7mg/g, being 1.5, 2, and 36 times higher than that of OX-Ver, OX, and Sep. The OX-Sep capacity for adsorbing Cd(II) was significantly lessened by decreasing the pH from 7 to 4 and raising the ionic strength from 0.01 N to 0.1 N. This trend was ascribed to electrostatic attraction between the Cd+2 in water and the negatively charged surface of OX-Sep. Besides, desorption studies at pH 4 showed that the average desorption percentage of Cd(II) adsorbed on OX-Sep was 80%. The characterization results and the effect of the operating conditions on the adsorption capacity proved that electrostatic attraction and cation exchange play a crucial role in the adsorption mechanism.

Point-of-Care Testing of Whole Blood for Liver Injury Auxiliary Diagnosis with Biothiols Activable Chemiluminescent Probe.

Liver injury significantly affects a patient's health and quality of life. However, timely and convenient diagnosis of this disease via whole blood detection remains challenging due to the lack of user-friendly and fast readout blood test methods. Herein, we developed such a method for the swift auxiliary diagnosis of liver injury via whole blood detection using a customed point-of-care testing (POCT) system consisting of a biothiols-activatable chemiluminescent probe and a hand-held POCT device. Biothiols served as the target to build the activable chemiluminescence probe due to their abnormal level in liver injury. Compared with fluorescent and electrical POCTs, this method is more convenient and has strong universality. By incorporating cyclodextrin via host-guest chemistry, we intensified chemiluminescence while mitigating chemical hemolysis caused by the dissolution of organic molecules, making this system suitable for whole blood analysis. Preliminary assessments in aqueous solutions, living cells, and mouse models confirmed its sensitivity, reliability, and feasibility. Simply mixing blood with the probe for 30 min yielded a clear signal readout within 15 s on the POCT device. Utilizing this portable detector, the reduced biothiol level was tested in 18 liver injury patient blood samples, and the results were similar to those measured by a commercial kit and in vivo imaging system. Thus, this work provides a universal platform for the fast and convenient detection of other biomarkers in whole blood samples and opens up possibilities for the rapid clinical diagnosis of diseases, enabling patients to conduct home self-examinations with ease.

Enhanced Cr(VI) removal via CPBr-modified MIL-88A@amine-functionalized GO: synthesis, performance, and mechanism.

Water contamination by heavy metals, especially chromium (VI), poses a critical environmental issue due to its carcinogenic nature and persistence in the environment. Addressing this, the current study develops an efficient adsorbent, CPBr-MIL-88A@AmGO, which utilizes the synergistic capabilities of Cetylpyridinium bromide-modified MIL-88A and amine-functionalized graphene oxide to enhance Cr(VI) removal from aqueous solutions. The obtained results indicate that CPBr-MIL-88A@AmGO achieves its highest removal efficacy at pH 2, where the interaction of CPBr and AmGO's positively charged centers significantly contributes to the adsorption processes. According to the Langmuir isotherm model, the composite's adsorption capacity reached a maximum of 306.75 mg/g. The adsorption kinetics adhered to a pseudo-second-order model along with the endothermic nature of the process. Although the presence of SO42- ions significantly reduces adsorption capacity, other interfering ions including Na+, K+, Ca2+, Cl-, and NO3- only slightly affect it. Remarkably, the composite maintains high removal efficiency, over 82%, even after 7 recycling tests, underscoring its potential for practical applications in water treatment systems. The proposed mechanism involves the contribution of electrostatic attractions, ion exchange, complexation, and the reduction of Cr(VI) to Cr(III) in the removal process. This study not only offers a potent solution for Cr(VI) remediation but also contributes to sustainable water resource management.

Superlong Metal-Organic Framework Micro-/Nanofibers for Selective Vitamin Absorption.

Superlong MOF-74-type micro/nanofibers, which have aspect ratios much higher than 200, are synthesized via nanoparticulate MOF-mediated recrystallization. Co-MOF-74 microfibers have high crystallinity, whereas Co-MOF-74-II nanofibers are composed of nanocrystals and amorphous phases, even though they have nanofibrous morphology. Both MOFs consist of plenty of micropores with diameters in the range of 1.0 to 2.0 nm, and they exhibit high thermal stability with a decomposition temperature higher than 260.0 °C. The MOFs are demonstrated for selective absorption of some vitamins including riboflavin, folic acid, and 5-methyltetrahydrofolate. Co-MOF-74-II nanofibers can efficiently absorb riboflavin and folic acid from their aqueous solution with absorption percentages approaching 90.0%, and they have enhanced capability for absorbing tocopherol in methanol. The micro/nanofibrous morphology, together with the capability for selective vitamin absorption, makes the novel MOFs highly promising for applications in micro-solid-phase extraction.

Multi-Colored Aqueous Ink for Rewritable Paper.

As sustainable and eco-friendly replacements to conventional paper, rewritable paper is a very attractive alternative for communication, information circulation, and storage. Development is made for rewritable paper using chromogenic materials that change its color in presence of external stimuli. However, the new techniques have faced several major challenges including feasible operational method, eco-friendly approach. Herein, a simple, convenient, and eco-friendly strategy is described for the preparation of rewritable paper substrate, and multi colored ink for efficient use in writing, painting or printing purpose. In addition, writing with "invisible ink" on the rewritable paper can be realized for potential anti-counterfeiting application. The written, painted, or printed information on the paper substrate can be easily erased using an aqueous solution. Thus, the original paper can be retrieved and the paper substrate can be reused multiple times. Besides, the written or printed information can be retained for a prolonged time at ambient conditions. Overall, this approach shows the rewritable paper as a prototype of multicolor writing/painting application, offering a sustainable solution for reducing paper waste and promoting environmental stewardship.

Design and evaluation of composite films for in situ synthesis and antibacterial activity of allicin vapour

AbstractAlthough allicin has potent antibiotic properties, its low stability, which is responsible for its persistent biological activity, has posed a significant challenge to its practical application in modern medicine. To harness the healing benefits of this phytochemical, known by humans for thousands of years, we propose a controlled in situ synthesis of allicin vapour near the site of infection. Considering the critical need for novel approaches to prevent pandemic scenarios caused by MDR bacteria, we suggest encapsulating and physically separating allicin precursors (substrate alliin and enzyme alliinase) in alginate-based films and spray-dried chitosan microparticles. The mechanical properties of the hydrogel films of various compositions were evaluated, as well as their ability to protect the encapsulated alliinase against thermal stress and control the overall rate of allicin release upon hydration. Furthermore, the non-contact antibacterial efficacy of free alliin/alliinase reaction mixture (aqueous solution) and three compartmentalised configurations, i.e. film-solution, film-particles, and double-film, were tested against selected bacterial strains, i.e. E. coli, S. epidermidis, and S. aureus. The results indicate that the formation of allicin vapour using the proposed compartmentalised systems addresses allicin’s stability issues and provides better control over the rate of allicin production. The observed antibacterial effect was comparable with directly formed allicin using higher initial amounts of both substances, which is given by diffusion limitations associated with encapsulation. These findings illustrate the potential of compartmentalised systems in developing nature-based wound dressings for infection prevention and promoting healing.