Preparation and thermal responsiveness of microencapsulated fluorinated liquids for automatic fire extinguishing

Most early-stage fires originating in small confined spaces may not be effectively mitigated by automatic fire-extinguishing systems. Leveraging the unique controlled release capability and barrier properties of microcapsules presents a promising avenue for developing multifunctional and intelligent fire-extinguishing agents tailored for early-stage fire suppression. This paper introduces two types of microcapsules that integrate automatic detection and fire extinguishing functions, utilizing fluorinated liquids specifically perfluoro(2-methyl-3-pentanone) and 1,1,1,2,2,3,4,5,5,5 decafluoro-3-methoxy-4(trifluoromethyl)-pentane as core materials. The preparation process was optimized, and the thermal response of the microcapsules was evaluated by directly incorporating them into combustible materials. The results indicated a correlation between the preparation method, coating efficiency, and thermal stability of microcapsules with the core-wall materials. When the fluoride solution in the core material reaches the thermal response threshold temperature, the gas pressure generated during vaporization and phase change can break through the shell, enabling early active fire protection. Beyond a specific threshold of additive microcapsules in the material, the material exhibits self-extinguishing potential during combustion. In cases where the additive amount falls short of achieving self-extinguishing, the fire-resistant performance of materials can be enhanced through various measures. For instance, reducing the amount of fire-extinguishing agents, delaying the ignition time of fuel, and lowering the heat release rate during combustion are effective strategies. Moreover, the degree of improvement is related to the additional amount and the type of core-wall materials. The thermal-response mechanism of microcapsules constitutes a comprehensive mechanism with physical and chemical effects. The finding of this research offer a new technical approach for microencapsulating high-boiling-point gas extinguishing agents, facilitating intelligent and precise prevention of early fires resulting from combustible materials.

A novel and stretchable carbon-nanotube/Ni@TiO2:W photocatalytic composite for the complete removal of diclofenac drug from the drinking water

We present the structural, morphological and photocatalytic properties of stretchable composites made with carbon nanotubes (CNTs), silicon rubber and Ni@TiO₂:W nanoparticles (TiWNi NPs) with average size of 37 ± 2 nm. Microscopy images showed that the TiWNi NPs decorated the surface of the CNT fibers, which are oriented in a preferential direction. TiWNi NPs presented a mixture of anatase/rutile phases with cubic structure. The performance of the TiWNi powders and stretchable composites was evaluated for the photocatalytic degradation of diclofenac (DCF) anti-inflammatory drug under ultraviolet-visible light. The results revealed that the maximum DCF degradation percentages were 34.6%, 91.9%, 97.1%, 98.5% and 100% for the CNT composite (stretched at 0%), TiWNi powders, CNT + TiWNi (stretched at 0%), CNT + TiWNi (stretched at 50%) and CNT + TiWNi (stretched at 100%), respectively. Thus, stretching the CNT + TiWNi composites was a good strategy to enhance the DCF degradation percentage from 97.1% to 100%, since stretching created additional defects (oxygen vacancies) that acted as electron sink, delaying the electron-hole recombination, and favors the DCF degradation. Raman/absorbance measurements confirmed the presence of such defects. Moreover, the reactive oxygen species (ROS) were determined by the scavenger's experiments and found that the main ROS were the ·OH and O₂^- radicals, which attacked the DCF molecules, causing their degradation. The results of this investigation confirmed that the stretchable CNT/TiWNi-based composites are a viable alternative to remove pharmaceutical contaminants from water and can be manually separated from the decontaminated water, which is unviable using photocatalytic powders.

Development and Optimization of Irinotecan-Loaded PCL Nanoparticles and Their Cytotoxicity against Primary High-Grade Glioma Cells

BACKGROUND

High-grade gliomas (HGGs) are highly malignant tumors with a poor survival rate. The inability of free drugs to cross the blood-brain barrier and their off-target accumulation result in dose-limiting side effects. This study aimed at enhancing the encapsulation efficiency (EE) of irinotecan hydrochloride trihydrate (IRH) within polycaprolactone (PCL) nanoparticles with optimized size and charge.

MATERIALS AND METHODS

IRH-loaded PCL nanoparticles were formulated using either the single emulsion (O/W, W/O and O/O) or double emulsion (W/O/O and W/O/W) solvent evaporation techniques. The nanoparticles were characterized for their size, zeta potential and EE, with the optimized nanoparticles being characterized for their drug release and cytotoxicity.

RESULTS

The amorphization of PCL and the addition of electrolytes to the aqueous phases of the W/O/W emulsion produced spherical nanoparticles with a mean diameter of 202.1 ± 2.0 nm and an EE of 65.0%. The IRH-loaded nanoparticles exhibited zero-order release and were cytotoxic against primary HGG cells.

CONCLUSION

The amorphization of PCL improves its EE of hydrophilic drugs, while the addition of electrolytes to the aqueous phases of the W/O/W emulsion enhances their EE further. IRH-loaded PCL nanoparticles have the potential to deliver cytotoxic levels of IRH over a sustained period of time, enhancing the cell death of HGGs.

Comparison of Linear Poly Ethylene Imine (LPEI) and Poly L-Lysine (PLL) in Fabrication of CHOK1 Cell-Loaded Multilayer Alginate Microcapsules

Purpose: Poly l-lysine (PLL) has been introduced as a strengthening covering layer for alginate microcapsules which are the most convenient way for cell encapsulation. Some disadvantages of PLL such as high price and low biocompatibility have prompted scientists to find better alternatives. Linear poly ethylene imine (LPEI), thanks to its highly similar structure to PLL, could be considered as a proper cost-effective alternative. In this study LPEI and PLL were compared as covering layers of cell-loaded alginate-LPEI-alginate (cALA) and alginate-PLL-alginate (cAPA) microcapsules. Methods: In addition to the physico-mechanical properties, the encapsulation efficiency, cell survival post encapsulation, cell viability, and cellular metabolic activity within the microcapsules were evaluated using trypan blue, live/dead cell staining, and MTT test, respectively. Results: Physico-mechanical evaluation of the microcapsules revealed that the cell microencapsulation process did not affect their shape, size, and mechanical stability. Although the encapsulation efficiency for cALA and cAPA was not different (P >0.05), cell survival post encapsulation was higher in cALA than in cAPA (P<0.05) which could be the reason for the higher cell viability and also cellular metabolic activity within these microcapsules in comparison to cAPA. Conclusion: Here, based on these results, ALA could be introduced as a preferable alternative to APA for cell encapsulation.

Comparison of different cationic polymers efficacy in fabrication of alginate multilayer microcapsules

In past decades, alginate-based multilayer microcapsules have been given important attention in various pharmaceutical investigations. Alginate-poly l lysine-alginate (APA) is studied the most. Due to the similarity between the structure of polyethyleneimine (PEI) and poly-L-lysine (PLL) and also lower price of PEI than PLL, this study was conducted to compare the efficacy of linear (LPEI) and branch (BPEI) forms of PEI with PLL as covering layers in fabrication of microcapsules. The microcapsules were fabricated using electrostatic bead generator and their shape/size, surface roughness, mechanical strength, and interlayer interactions were also investigated using optical microscopy, AFM, explosion test and FTIR, respectively. Furthermore, cytotoxicity was evaluated by comparing the two anionic final covering layers alginate (Alg) and sodium cellulose sulphate (NCS) using MTT test. BPEI was excluded from the rest of the study due to its less capacity to strengthen the microcapsules and also the aggregation of the resultant alginate-BPEI-alginate microcapsules, while LPEI showed properties similar to PLL. MTT test also showed that NCS has no superiority over Alg as final covering layer. Therefore, it is concluded that, LPEI could be considered as a more cost effective alternative to PLL and a promising subject for future studies.

Lowering side effects of NSAID usage in osteoarthritis: recent attempts at minimizing dosage

INTRODUCTION

Osteoarthritis is a burdensome disease that causes progressive damage to articular cartilage. Non-steroidal anti-inflammatory drugs (NSAIDs) are one of the preferred treatments for symptomatic relief. However, NSAIDs can cause serious dose-dependent side effects, which has prompted experts to recommend the minimization of NSAID dosage.

AREAS COVERED

This review focuses on three broad strategies that are currently being investigated or implemented to minimize NSAID dosage: nano-formulation, encapsulation, and topical delivery. The benefits, challenges and current status of these methods are discussed.

EXPERT OPINION

Multiple strategies are under investigation to lower NSAID dosage. There is great potential in developing formulations that utilize more than one of these strategies together. However, there are challenges to developing these lower dose preparations. In order to maximize the clinical potential of the abundance of NSAIDs that are both available and being developed, there is a major need for additional clinical studies directly comparing safety and efficacy of different preparations.

Improvement of the antibacterial activity of daptomycin-loaded polymeric microparticles by Eudragit RL 100: an assessment by isothermal microcalorimetry

The aim of the present study was to develop novel daptomycin-loaded acrylic microparticles with improved release profiles and antibacterial activity against two clinically relevant methicillin-susceptible and methicillin-resistant Staphylococcus aureus strains (MSSA and MRSA, respectively). Daptomycin was encapsulated into poly(methyl methacrylate) (PMMA) and PMMA-Eudragit RL 100 (EUD) microparticles by a double emulsion-solvent evaporation method. For comparison purposes similar formulations were prepared with vancomycin. Particle morphology, size distribution, encapsulation efficiency, surface charge, physicochemical properties, in vitro release and biocompatibility were assessed. Particles exhibited a micrometer size and a spherical morphology. The addition of EUD to the formulation caused a shift in the surface charge of the particles from negative zeta potential values (100% PMMA formulations) to strongly positive. It also improved daptomycin encapsulation efficiency and release, whereas vancomycin encapsulation and release were strongly hindered. Plain and antibiotic-loaded particles presented comparable biocompatibility profiles. The antibacterial activity of the particles was assessed by isothermal microcalorimetry against both MSSA and MRSA. Daptomycin-loaded PMMA-EUD particles presented the highest antibacterial activity against both strains. The addition of 30% EUD to the daptomycin-loaded PMMA particles caused a 40- and 20-fold decrease in the minimum inhibitory (MIC) and bactericidal concentration (MBC) values, respectively, when compared to the 100% PMMA formulations. On the other hand, vancomycin-loaded microparticles presented the highest antibacterial activity in PMMA particles. Unlike conventional methods, isothermal microcalorimetry proved to be a real-time, sensitive and accurate method for assessment of antibacterial activity of antibiotic-loaded polymeric microparticles. Finally, the addition of EUD to formulations proved to be a powerful strategy to improve daptomycin encapsulation efficiency and release, and consequently improving the microparticles activity against two relevant S. aureus strains.

Prospects of pharmaceuticals and biopharmaceuticals loaded microparticles prepared by double emulsion technique for controlled delivery

Several methods and techniques are potentially useful for the preparation of microparticles in the field of controlled drug delivery. The type and the size of the microparticles, the entrapment, release characteristics and stability of drug in microparticles in the formulations are dependent on the method used. One of the most common methods of preparing microparticles is the single emulsion technique. Poorly soluble, lipophilic drugs are successfully retained within the microparticles prepared by this method. However, the encapsulation of highly water soluble compounds including protein and peptides presents formidable challenges to the researchers. The successful encapsulation of such compounds requires high drug loading in the microparticles, prevention of protein and peptide degradation by the encapsulation method involved and predictable release, both rate and extent, of the drug compound from the microparticles. The above mentioned problems can be overcome by using the double emulsion technique, alternatively called as multiple emulsion technique. Aiming to achieve this various techniques have been examined to prepare stable formulations utilizing w/o/w, s/o/w, w/o/o, and s/o/o type double emulsion methods. This article reviews the current state of the art in double emulsion based technologies for the preparation of microparticles including the investigation of various classes of substances that are pharmaceutically and biopharmaceutically active.