Enhanced selectivity and performance of heterogeneous cation exchange membranes through addition of sulfonated and protonated Montmorillonite

Physicochemical properties and micro-interaction between micro-nanoparticles and anterior corneal multilayer biological interface film for improving drug delivery efficacy: the transformation of tear film turnover mode

Recently, various novel drug delivery systems have been developed to overcome ocular barriers in order to improve drug efficacy. We have previously reported that montmorillonite (MT) microspheres (MPs) and solid lipid nanoparticles (SLNs) loaded with the anti-glaucoma drug betaxolol hydrochloride (BHC) exhibited sustained drug release and thus intraocular pressure (IOP) lowering effects. Here, we investigated the effect of physicochemical particle parameters on the micro-interactions with tear film mucins and corneal epithelial cells. Results showed that the MT-BHC SLNs and MT-BHC MPs eye drops significantly prolonged the precorneal retention time due to their higher viscosity and lower surface tension and contact angle compared with the BHC solution, with MT-BHC MPs exhibiting the longest retention due to their stronger hydrophobic surface. The cumulative release of MT-BHC SLNs and MT-BHC MPs was up to 87.78% and 80.43% after 12 h, respectively. Tear elimination pharmacokinetics study further confirmed that the prolonged precorneal retention time of the formulations was due to the micro-interaction between the positively charged formulations and the negatively charged tear film mucins. Moreover, the area under the IOP reduction curve (AUC) of MT-BHC SLNs and MT-BHC MPs was 1.4 and 2.5 times that of the BHC solution. Accordingly, the MT-BHC MPs also exhibit the most consistent and long-lasting IOP-lowering effect. Ocular irritation experiments showed no significant toxicity of either. Taken together, MT MPs may have the potential for more effective glaucoma treatment.

Material Design Strategies for Recovery of Critical Resources from Water

Population growth, urbanization, and decarbonization efforts are collectively straining the supply of limited resources that are necessary to produce batteries, electronics, chemicals, fertilizers, and other important products. Securing the supply chains of these critical resources via the development of separation technologies for their recovery represents a major global challenge to ensure stability and security. Surface water, groundwater, and wastewater are emerging as potential new sources to bolster these supply chains. Recently, a variety of material-based technologies have been developed and employed for separations and resource recovery in water. Judicious selection and design of these materials to tune their properties for targeting specific solutes is central to realizing the potential of water as a source for critical resources. Here, the materials that are developed for membranes, sorbents, catalysts, electrodes, and interfacial solar steam generators that demonstrate promise for applications in critical resource recovery are reviewed. In addition, a critical perspective is offered on the grand challenges and key research directions that need to be addressed to improve their practical viability.

AIEgen Intercalated Nanoclay-Based Photodynamic/Chemodynamic Theranostic Platform for Ultra-Efficient Bacterial Eradication and Fast Wound Healing

With the emergence and global spread of bacterial resistance, pathogenic bacterial infections have become a serious threat to human health. Thus, therapeutic strategies with highly antibacterial efficacy and a low tendency to induce drug resistance are strongly desired to combat bacterial infections. Here, an ultra-efficient photodynamic/chemodynamic theranostics platform is developed by intercalating an aggregation-induced emission (AIE) photosensitizer, TPCI, into the nanolayers of iron-bearing montmorillonite (MMT). The formed TPCI/MMT composite can not only perform efficient photodynamic therapy (PDT) through a burst generation of singlet oxygen (¹O₂) upon white light illumination but also continuously implement chemodynamic therapy (CDT) by converting endogenous hydrogen peroxide into highly toxic hydroxyl radicals (^•OH) due to iron release. In addition, the fluorescence of TPCI/MMT can be activated due to the AIE feature of TPCI, which helps guide the location of the antimicrobials. The combination of such powerful bombs (PDT) and unremitting ambushes (CDT) in TPCI/MMT can synergistically and effectively eliminate bacteria and promote faster wound healing in vivo with good biocompatibility and low side effects. The smart and simple design of TPCI/MMT provides a representative paradigm for achieving efficient antimicrobials to combat the coming resistance crisis.

Preparation of Chitosan/Clay Composites for Safe and Effective Hemorrhage Control

Uncontrolled hemorrhage from trauma or surgery can lead to death. In this study, chitosan/kaolin (CSK) and chitosan/montmorillonite (CSMMT) composites were prepared from chitosan (CS), kaolin (K), and montmorillonite (MMT) as raw materials to control bleeding. The physiochemical properties and surface morphology of CSK and CSMMT composites were analyzed by Fourier transform infrared spectrometry (FT-IR), X-ray diffraction (XRD), scanning electron microscopy (SEM), zeta potentials, and X-ray fluorescence (XRF). The hemostatic mechanism was measured in vitro by activated partial thromboplastin time (APTT), prothrombin time (PT), in vitro clotting time, erythrocyte aggregation, and thromboelastogram (TEG). The hemostasis ability was further verified by using tail amputation and arteriovenous injury models in rats. The biocompatibility of CSK and CSMMT was evaluated by in vitro hemolysis, cytotoxicity assays, as well as acute toxicity test and skin irritation tests. The results show that CSK and CSMMT are promising composite materials with excellent biocompatibility and hemostatic properties that can effectively control bleeding.

Evaluation of Novel Tranexamic Acid/Montmorillonite Intercalation Composite, as a New Type of Hemostatic Material

Radiation enteritis-clinically manifested as diarrhea, intestinal bleeding, and so on-is frequently caused when the body is exposed to radiation or radiotherapy because the intestine is radiation-sensitive as an abdominal organ. Therefore, strategies to modulate intestinal hemostasis had inspired an important research trend in the process of preventing and treating radiation enteritis. Based on the structural characteristics of montmorillonite (MMT) and the hemostatic drug tranexamic acid (TXA) which was used clinically to treat enteritis, the tranexamic acid-montmorillonite composite material (TXA-MMT) was prepared through intercalation composite technology. According to the analysis of FTIR, XRD, TG-DTG, SEM, and XRF, the prepared TXA-MMT was verified that tranexamic acid could intercalate into layers of montmorillonite. To evaluate the biocompatibility, two experiments were conducted by in vitro hemolysis and in vitro cytotoxicity experiments and results showed that TXA-MMT exhibited good visible biocompatibility. Activated partial thromboplastin time, prothrombin time, and in vitro clotting time were adopted to determine the hemostatic effect of TXA-MMT. Compared with other groups, TXA-MMT revealed a significant decrease in clotting time variations, APTT, and PT. In addition, to investigate the preventive effect of TXA-MMT by the intervention of radiation enteritis mice, inflammatory factors IL-1β, IL-6, and TNF-α and the content of endotoxin in the serum of mice were detected. It demonstrated that TXA-MMT reduced the levels of these factors. Besides, the expression and the pathological changes of the small intestine tissue of mice were relieved. Our findings suggests that TXA-MMT as a promising intercalation composite has a great potential for application in the field of intestinal hemostasis.

A comprehensive review on the synthesis and applications of ion exchange membranes

Ion exchange membranes (IEMs) are undergoing prosperous development in recent years. More than 30,000 papers which are indexed by Science Citation Index Expanded (SCIE) have been published on IEMs during the past twenty years (2001-2020). Especially, more than 3000 papers are published in the year of 2020, revealing researchers' great interest in this area. This paper firstly reviews the different types (e.g., cation exchange membrane, anion exchange membrane, proton exchange membrane, bipolar membrane) and electrochemical properties (e.g., permselectivity, electrical resistance/ionic conductivity) of IEMs and the corresponding working principles, followed by membrane synthesis methods, including the common solution casting method. Especially, as a promising future direction, green synthesis is critically discussed. IEMs are extensively applied in various applications, which can be generalized into two big categories, where the water-based category mainly includes electrodialysis, diffusion dialysis and membrane capacitive deionization, while the energy-based category mainly includes reverse electrodialysis, fuel cells, redox flow battery and electrolysis for hydrogen production. These applications are comprehensively discussed in this paper. This review may open new possibilities for the future development of IEMs.

Wettability and contact angle affect precorneal retention and pharmacodynamic behavior of microspheres

In the present study, we describe the development of betaxolol hydrochloride and montmorillonite with ion exchange in a single formulation to create a novel micro-interactive dual-functioning sustained-release delivery system (MIDFDS) for the treatment of glaucoma. Betaxolol hydrochloride molecule was loaded onto the montmorillonite by ion exchange and MIDFDS formation was confirmed by XPS data. MIDFDS showed similar physicochemical properties to those of Betoptic, such as particle size, pH, osmotic pressure, and rheological properties. Nevertheless, the microdialysis and intraocular pressure test revealed better in vivo performance of MIDFDS, such as pharmacokinetics and pharmacodynamics. With regards to wettability, MIDFDS had a larger contact angle (54.66 ± 5.35°) than Betoptic (36.68 ± 1.77°), enabling the MIDFDS (2.93 s) to spread slower on the cornea than Betoptic (2.50 s). Moderate spreading behavior and oppositely charged electrostatic micro-interactions had a comprehensive influence on micro-interactions with the tear film residue, resulting in a longer precorneal retention time. Furthermore, MIDFDS had a significant sustained-release effect, with complete release near the cornea. The dual-functioning sustained-release carrier together with prolonged pre-corneal retention time (80 min) provided sufficiently high drug concentrations in the aqueous humor to achieve a more stable and long-term IOP reduction for 10 h. In addition, cytotoxicity and hemolysis tests showed that MIDFDS had better biocompatibility than Betoptic. The dual-functioning microspheres presented in this study provide the possibility for improved compliance due to low cytotoxicity and hemolysis, which suggests promising clinical implications.