Synthesis and characterization of porous CaCO3 microspheres templated by yeast cells and the application as pH value-sensitive anticancer drug carrier

Characteristics of Circulating Fluidized Bed Combustion (CFBC) Ash as Carbon Dioxide Storage Medium and Development of Construction Materials by Recycling Carbonated Ash

This study validates the attributes of the mineral carbonation process employing circulating fluidized bed combustion (CFBC) ash, which is generated from thermal power plants, as a medium for carbon storage. Furthermore, an examination was conducted on the properties of construction materials produced through the recycling of carbonated circulating fluidized bed combustion (CFBC) ash. The carbonation characteristics of circulating fluidized bed combustion (CFBC) ash were investigated by analyzing the impact of CO2 flow rate and solid content. Experiments were conducted to investigate the use of it as a concrete admixture by replacing cement at varying percentages ranging from 0% to 20% by weight. The stability and setting time were subsequently measured. To produce foam concrete, specimens were fabricated by substituting 0 to 30 wt% of the cement. Characteristics of the unhardened slurry, such as density, flow, and settlement depth, were measured, while characteristics after hardening, including density, compressive strength, and thermal conductivity, were also assessed. The findings of our research study validated that the carbonation rate of CFBC ash in the slurry exhibited distinct characteristics compared to the reaction in the solid-gas system. Manufactured carbonated circulating fluidized bed combustion (CFBC) ash, when used as a recycled concrete mixture, improved the initial strength of cement mortar by 5 to 12% based on the 7-day strength. In addition, it replaced 25 wt% of cement in the production of foam concrete, showing a density of 0.58 g/cm3, and the 28-day strength was 2.1 MPa, meeting the density standard of 0.6 grade foam concrete.

Functionalized Calcium Carbonate-Based Microparticles as a Versatile Tool for Targeted Drug Delivery and Cancer Treatment

Nano- and microparticles are increasingly widely used in biomedical research and applications, particularly as specific labels and targeted delivery vehicles. Silica has long been considered the best material for such vehicles, but it has some disadvantages limiting its potential, such as the proneness of silica-based carriers to spontaneous drug release. Calcium carbonate (CaCO3) is an emerging alternative, being an easily available, cost-effective, and biocompatible material with high porosity and surface reactivity, which makes it an attractive choice for targeted drug delivery. CaCO3 particles are used in this field in the form of either bare CaCO3 microbeads or core/shell microparticles representing polymer-coated CaCO3 cores. In addition, they serve as removable templates for obtaining hollow polymer microcapsules. Each of these types of particles has its specific advantages in terms of biomedical applications. CaCO3 microbeads are primarily used due to their capacity for carrying pharmaceutics, whereas core/shell systems ensure better protection of the drug-loaded core from the environment. Hollow polymer capsules are particularly attractive because they can encapsulate large amounts of pharmaceutical agents and can be so designed as to release their contents in the target site in response to specific stimuli. This review focuses first on the chemistry of the CaCO3 cores, core/shell microbeads, and polymer microcapsules. Then, systems using these structures for the delivery of therapeutic agents, including drugs, proteins, and DNA, are outlined. The results of the systematic analysis of available data are presented. They show that the encapsulation of various therapeutic agents in CaCO3-based microbeads or polymer microcapsules is a promising technique of drug delivery, especially in cancer therapy, enhancing drug bioavailability and specific targeting of cancer cells while reducing side effects. To date, research in CaCO3-based microparticles and polymer microcapsules assembled on CaCO3 templates has mainly dealt with their properties in vitro, whereas their in vivo behavior still remains poorly studied. However, the enormous potential of these highly biocompatible carriers for in vivo applications is undoubted. This last issue is addressed in depth in the Conclusions and Outlook sections of the review.

Recyclable and Efficient Recovery of Ca and S from Phosphogypsum by Using Multistep Precipitation

The resource utilization of phosphogypsum (PG) is the key to promote the green development of the phosphorus chemical industry. The natural environment and public safety are significantly threatened by the enormous volume of PG storage. In this study, Ca and S were successfully recovered from the PG via a multistep precipitation in the NaOH-BaCO3 system. The alkali solution can be recycled five times, with a first recovery ratio of about 97.9%, and the decomposition ratio of PG remained above 70% after five cycles. In addition, the recovery ratios of Ca and S in PG are 99.9 and 82.5%, respectively. The product of BaSO4 can be used as a weighting agent for oil and natural gas drilling mud. The BaSO4 can also be used as wave-absorbing materials, and its reflection loss value reaches 97.8% of the analytical purity BaSO4. This work provides a new idea for the efficient recycling of Ca and S in PG with an outstanding application prospect.

Tumor tropic delivery of FU.FA@NSs using mesenchymal stem cells for synergistic chemo-photodynamic therapy of colorectal cancer

To overcome the limitations associated with the targeting abilities of nanotherapeutics and drug loading capacity of mesenchymal stem cells (MSCs), the present study relies on the combination of MSCs tumor tropism with the controlled release function of nano-based drug delivery platforms to achieve tumor-specific accumulation of chemotherapeutics with minimal off-target effects. 5-fluorouracil (5-FU)-containing ceria (CeNPs) coated calcium carbonate nanoparticles (CaNPs) were functionalized with folinic acid (FA) to develop drug-containing nanocomposites (Ca.FU.Ce.FA NCs). NCs were then conjugated with graphene oxide (GO) and decorated with silver nanoparticles (Ag°NPs) to form FU.FA@NS, a rationally designed drug delivery system with O₂ generation capacity that alleviates tumor hypoxia for improved photodynamic therapy. Engineering of MSCs with FU.FA@NSs provided successful loading and long-term retention of therapeutics on the surface membrane with minimal changes to the functional properties of MSCs. Co-culturing of FU.FA@NS.MSCs with CT26 cells upon UVA exposure revealed enhanced apoptosis in tumor cells through ROS-mediated mitochondrial pathway. FU.FA@NSs released from MSCs were effectively taken up by CT26 cells via a clathrin-mediated endocytosis pathway and distributed their drug depots in a pH, H₂O₂, and UVA-stimulated fashion. Therefore, the cell-based biomimetic drug delivery platform formulated in the current study could be considered a promising strategy for targeted chemo-photodynamic therapy of colorectal cancer.

Removal of nanoplastics from aqueous solution by aggregation using reusable magnetic biochar modified with cetyltrimethylammonium bromide

Nanoplastics (NPs) pollution has become an emerging threat to the aquatic environment and its organisms. The removal of NPs from contaminated water is a global challenge. In this study, an efficient and reusable composite was prepared from cetyltrimethylammonium bromide (CTAB) modified magnetic biochar. The performances of CTAB modified magnetic biochar (CMB) to remove polystyrene (PS) and carboxylate-modified polystyrene (CPS) nanoparticles from water were systematically evaluated. The results showed that the PS and CPS removal performance of magnetic biochar was improved by CTAB modification. These increases were assigned to the increase in the surface hydrophobicity of CMB. Due to the strong electrostatic repulsion between the nanoparticles, PS and CPS maintained high stability in alkaline conditions, resulting in a significant decrease in removal efficiency. The removal efficiency was decreased to 67.4% for PS and to 40.7% for CPS at pH 11. The inhibition effects of NaCl on the PS and CPS removal efficiencies were decreased gradually with the increase of NaCl concentration. Among the anions studied, H₂PO₄^- had the biggest impact on the removal performance of CMB. Besides, CMB could be used to remove PS and CPS in real surface water, and the removal efficiencies of PS and CPS were 95.3% and 97.8%, respectively. Particularly, the removal efficiencies of PS and CPS were 90.2% for PS and 94.8% for CPS when CMB was recycled five times. According to the characterization results of XRD, TGA, SEM, FTIR and XPS, PS and CPS nanoparticles were removed by CMB from water mainly through aggregation instead of adsorption. The efficient removal of PS and CPS by CMB via aggregation process offers new insight into the removal of NPs from aquatic environment.

Synthesis of Hollow Calcium Carbonate Microspheres by a Template Method for DOX Loading and Release with Carbon Dots Photosensitivity

Calcium carbonate, as the main inorganic component of human bones and teeth, has good biocompatibility and bioactivity and finds increasing applications in the field of bone drug carriers. In this study, hollow calcium carbonate microspheres were synthesized by a water hydrothermal method using folic acid as a template. Before drug loading, the prepared calcium carbonate microspheres were subjected to aminidation, carboxylation, and vinylenimine modification. The hollow calcium carbonate microspheres loaded with doxorubicin hydrochloride (DOX) were further incorporated with light-emitting carbon quantum dots(CQDs) and hyaluronic acid (HA). The result showed that the drug loading capacity in the as-prepared calcium carbonate was 179.064 mg/g. In the simulated solutions of cellular metabolism containing various concentrations of reduced glutathione(GSH), the sustained release of DOX was confirmed qualitatively by the luminescence of the CQDs. The DOX release rate was measured quantitively by UV absorption spectra. The highest release rate reached 85.99% in a simulated solution of 0.005 mol/L GSH solution, and the release rate could vary intelligently with the concentration.