Solubility Limit Research Articles

Development and in vitro Evaluation of Cannabidiol Mucoadhesive Buccal Film Formulations Using Hot-Melt Extrusion Technology

Introduction: Cannabidiol (CBD) has sparked considerable interest because of its wide range of pharmacological uses and the fact that it does not induce psychoactive effects. CBD formulation development presents significant challenges due to its limited water solubility and susceptibility to first-pass metabolism, both of which restrict its overall bioavailability. The current research aimed to use hot-melt extrusion (HME) technology to develop mucoadhesive buccal films to improve CBD solubility and reduce first-pass metabolism. Methods: Five formulations containing 10% w/w CBD were extruded using a counter-rotating twin-screw extruder (Haake Minilab II, Thermo Fisher Scientific). Different characterization studies were conducted on the developed formulations. Results: Differential scanning calorimetry (DSC) revealed that the CBD endothermic peak disappeared in some of the developed films, indicating that CBD was converted from crystalline to amorphous form. A bio-adhesion study showed that the formulations containing Carbopol® (BF2, BF3, BF4, and BF5) had higher adhesiveness properties. In vitro release and solubility studies showed an increase in CBD release and water solubility in the developed formulations when compared to pure CBD. Stability studies revealed that CBD content and release in the lead formulation (BF2) was stable over 15 months. Conclusion: The current study demonstrates that HME was successfully used as an approach to develop CBD mucoadhesive buccal films and CBD solubility was enhanced.

A Comprehensive Review of Self-Nanoemulsifying Systems in the Delivery of Herbal Drugs.

Self-nanoemulsifying drug delivery systems (SNEDDS) are an isotropic mixture of oils, co-surfactants, and surfactants and can form fine O/W Nanoemulsions in aqueous media. These components are advantageous in terms of improved solubility and bioavailability. Limited permeability, solubility, and bioavailability remain a significant challenge in developing herbal drugs. This review explores the potential of self-nanoemulsifying drug delivery systems (SNEDDS) as a promising strategy to overcome this problem. The SNEDDS is considered a novel technique for the delivery of low water-soluble drugs. It can bypass the first-pass metabolism, resulting in steady and sustained drug levels in the systemic circulation. The present article provides a comprehensive overview of the SNEDDS formulation of herbal drugs. It includes their composition, characterization, in vitro and in vivo studies conducted in various disease conditions, and pharmacokinetic studies.

Tumor Microenvironment-Responsive Zn(II)-Porphyrin Nanotheranostics for Targeted Sonodynamic Therapy.

As a novel noninvasive tumor therapy, sonodynamic therapy (SDT) attracts booming concerns. However, the limited water solubility, inadequate biocompatibility, and low targeting ability of conventional sonosensitizers significantly hinder their potential for clinical application. Herein, novel zinc(II)-porphyrin nanotheranostics (HA@Zn-TCPP) were fabricated in which the zinc(II)-porphyrin (TCPP) metal-organic framework was first constructed by a simple thermal reaction, followed by the addition of hyaluronic acid (HA) for modification. The specific targeting ability of HA facilitated the internalization of HA@Zn-TCPP within tumor cells, resulting in its preferential accumulation in tumor tissues that exhibit CD44 receptor overexpression. The acidic tumor microenvironment induced the rapid decomposition of HA@Zn-TCPP, releasing free TCPP for activating SDT. This controllable generation of reactive oxygen species (ROS) could effectively decrease damage to normal tissues. The HA@Zn-TCPP exhibited remarkable antitumor effects in experiments, achieving a tumor inhibition rate of up to 82.1% when under ultrasound. This finding provides an imperative strategy to develop novel sonosensitizers for enhanced SDT.

Separation and production of metallic magnesium from salt lake brine by extraction-electrodeposition technology

The conventional methods of producing metallic magnesium involve high temperatures, high pollution, and high energy consumption. Herein, the separation and production of metallic magnesium from salt lake brine was carried out using an environmentally friendly extraction-electrodeposition method. 16 functional ionic liquids, consisting of four saponified anions and four quaternary ammonium salt cations, were synthesized and employed as both extractants and supporting electrolytes. The study showed that the compound [A336][V10], which was produced using methyltrioctylammonium ([A336]+) and saponified neodecanoic acid ([V10]−), exhibited a significant extraction rate of Mg2+ and electrical conductivity in methyl isobutyl ketone (MIBK). The extraction efficiency for Mg2+ with a concentration of 54.04 g·L−1 was found to be 60.98%. After extraction, the electrical conductivity of the organic phase was measured to be 649 μS·cm−1. The extraction mechanism and phase equilibria showed that the organic system exhibited limited solubility with the aqueous phase, and the Mg2+ in the brine was extracted by [A336][V10] in the form of MgCl2·2[A336][V10] through monodentate coordination with the carboxyl group in [V10]−. Following extraction, metallic magnesium was successfully electrodeposited from the organic phase. This is the first time that metallic magnesium was directly produced from a common extraction system at room temperature. This method avoids both the dehydration of MgCl2·6H2O and the melting of anhydrous MgCl2 at high temperatures, which are typically encountered in the traditional procedure of producing metallic magnesium from brines, and it offers a new strategy for metallic magnesium production with low energy consumption.

Unconventional exchange bias and enhanced spin pumping efficiency due to diluted magnetic oxide at the Co/ZnO interface

Exchange bias (EB) is normally created by the interfacial exchange coupling at a ferromagnetic/antiferromagnetic (FM/AFM) interface. FM/AFM interfaces have also been proved to perform enhanced spin angular momentum transfer efficiency in spin pumping (SP), compared with typical FM/nonmagnetic interfaces. Here, we report an unexpected EB and enhanced SP between a ferromagnet and semiconductor. Considerable EB has been observed in Co films grown on ZnO single crystal due to the interface antiferromagnetism of the Zn1−xCoxO (x depends on the Co solubility limit in ZnO) layer. Moreover, SP measurements demonstrate a giant spin pumping efficiency at the Co/ZnO interface with a bump (spin mixing conductance Geff↑↓= 28 nm−2) around the blocking temperature TB ∼ 75 K. The enhanced SP is further confirmed by inverse spin Hall effect measurements and the spin Hall angle θISHE of Zn1−xCoxO is estimated to be 0.011. The bound magnetic polarons with s–d exchange interaction between donor electrons and magnetic cation ions in Zn1−xCoxO play a key role in the formation of antiferromagnetism with giant Geff↑↓. Our work provides a new insight into spin physics at FM/semiconducting interfaces.

Mechanochemical synthesis and characterization of poly[(aniline-co-N-(4-sulfophenyl) aniline] nanofibers and its nanocomposite with titanium dioxide nanoparticles and study of their efficiency in hybrid solar cell

The advantages of polyaniline for application in new generation solar cells include its cost-effectiveness, environmentally friendly synthesis, remarkable stability, and the ability to modify the bandgap through the synthesis of its nanocomposites. But a challenge for its nanostructures is the limited solubility in non-toxic solvents, including water, which limits their processability in coating techniques. We overcame this challenge by synthesizing its copolymer with diphenylamine-4-sulfonate and its nanocomposite with titanium dioxide nanoparticles (TiO2NPs). So through a solid-state and template-free technique and using sodium diphenylamine-4-sulfonate, aniline hydrochloride salt, TiO2NPs, and FeCl3∙6 H2O as an oxidant, poly(N-(sulfophenyl)aniline) nanoflowers (PSANFLs), poly [(aniline-co-N-(4-sulfophenyl) aniline] nanofibers (PAPSANFs), poly(N-(sulfophenyl)aniline) nanofibers/titanium dioxide nanoparticles (PSANFs/TiO2NPs), and poly (aniline-co-N-(4-sulfophenyl)aniline nanofibers/titanium dioxide nanoparticles (PAPSANFs/TiO2NPs) were synthesized. Characterization of the synthesized samples was carried out through field emission scanning electron microscopy (FE-SEM), Fourier-transform infrared spectra, ultraviolet-visible spectra (UV-Vis), cyclic voltammetry (CV), and elemental analysis (CHNS). The FE-SEM images clearly illustrate that the synthesized samples are of nanoscale dimensions. The band gap values of 2.23 eV for PSANFs/TiO2NPs and 1.96 eV for PAPSANFs/TiO2NPs nanocomposites were determined through electrochemical calculations based on cyclic voltammetry curves, showcasing the complementary properties of n and p semiconductors. Using doctor blade method to prepare films from synthesized materials and the architectural pattern of ITO│TiO2NPs│semiconductor sample│Al, all hybrid solar cells are fabricated. The I-V characteristics and power conversion efficiency (PCE) of the samples were examined and discussed. The PCE values for the four samples were found to be in the range of 0.20–0.82 %.

Designing Alkylammonium Cations for Enhanced Solubility of Anionic Active Materials in Redox Flow Batteries: The Role of Bulk and Chain Length.

Advancing grid-scale energy storage technologies is crucial for realizing a fully renewable energy landscape, with non-aqueous redox flow batteries (NRFBs) presenting a promising solution. One of the current challenges in NRFBs stems from the low energy density of redox active materials, primarily due to their limited solubility in non-aqueous solvents. Herein, this study explores the solubility of vanadium(IV/V) bis-hydroxyiminodiacetate (VBH) crystals in acetonitrile, aiming to use them as anionic catholytes in NRFBs. We focused on enhancing VBH solubility by modifying the structure of the alkylammonium cation. Employing periodic density functional theory and a solvation model, we calculated the dissolution free energy ([[EQUATION]]), which includes sublimation ([[EQUATION]]) and solvation ([[EQUATION]]) energies. Our results indicate that neither elongating straight-chain alkyl groups beyond a tetrabutylammonium baseline nor introducing bulky substituents at the nitrogen center significantly enhances solubility. However, the introduction of carbon spacers combined with terminal bulky substituents markedly improves solubility by favorably altering both [[EQUATION]] and [[EQUATION]]. These findings underline the nuanced impact of cation structure on solubility and suggest a viable approach to optimize VBH-based anionic catholytes. This advancement promises to enhance NRFB efficiency and sustainability, marking a significant step forward in energy storage technology.

Polymeric additives to sustain the dissolution enhancement of niclosamide nanocrystals formed via freeze drying

Nanocrystal formation is an effective method to increase the dissolution of drug compounds with limited solubilities. Niclosamide is a sparingly soluble compound, and it also tends to become an even less soluble monohydrate upon contact with dissolution media. We utilized freeze drying to successfully generate niclosamide nanocrystals, which displayed rapid initial dissolution but also suffered from the expedited formation of the monohydrate. Therefore, we explored some pharmaceutically acceptable polymers to overcome the unfavorable anhydrate-to-monohydrate transformation. Poly(vinylpyrrolidone-co-vinyl acetate) (Mw 45000–70000) effectively retarded the monohydrate formation in a concentration-dependent manner, and 3–5% in the drug-polymer mixture was enough to sustain the enhanced initial dissolution of niclosamide nanocrystals. The area under the dissolution curve tripled due to the combined effect of the nanocrystal formation and the monohydrate inhibition. This study demonstrates an example of the one-pot freeze-drying process to form an optimized drug-additive mixture to realize the full potential of drug nanocrystals.

Pulmonary delivery of forsythin-phospholipid complexes improves the lung anti-inflammatory efficacy in mice by enhancing dissolution and lung tissue affinity

Forsythin, currently in phase II clinical trials in China for the treatment of the common cold and influenza, faces challenges in achieving adequate lung drug exposure due to its limited dissolution and permeability, thereby restricting its therapeutic efficacy. The objective of this work was to formulate a forsythin-phospholipid complex (FPC) to enhance its dissolution properties and lung affinity with a particular view to improving pulmonary drug exposure and anti-inflammatory response. The results revealed that forsythin reacted with dipalmitoyl-phosphatidylcholine to form a stable, nanosized FPC suspension. This formulation significantly improved the in vitro drug's dissolution, cellular uptake, and lung affinity compared to its uncomplexed form. Intratracheal administration of FPC in a mouse model of acute lung injury induced by lipopolysaccharide (LPS) resulted in a substantial increase in drug exposure to lung tissues (39.6-fold) and immune cells in the epithelial lining fluid (198-fold) compared to intraperitoneal injection. In addition, FPC instillation exhibited superior local anti-inflammatory effects, leading to improved survival rates among mice with LPS-induced acute respiratory distress syndrome, outperforming both instilled forsythin and injected FPC. Overall, this work demonstrated the potential of phospholipid complexes as a viable option for developing inhalation products for drugs with limited solubility and permeability properties.

Aqueous solubility enhancement of theobromine using eco-friendly hydrotropic phenomena

Theobromine, a bioactive compound found in cacao beans, is recognized for its pharmacological health benefits, such as improving heart health by lowering blood pressure, enhancing cognitive function, supporting respiratory health, providing antioxidant benefits, reducing inflammation, and promoting dental health. However, its limited solubility in water poses challenges for therapeutic applications, necessitating methods to enhance its solubility. The approach to enhance its bioavailability making it more effective for medicinal use and easier to incorporate into various pharmaceutical and nutraceutical products. Hydrotropic solubilization, utilizing the amphiphilic nature of sodium benzoate, is employed to improve the solubility of theobromine. Through systematic investigation of varying concentrations (0–3 mol/L) of sodium benzoate and temperature conditions ranging between 303 and 333 K, this study is aimed to elucidate their effects on the solubility of theobromine. Standardized protocols were utilized to measure the concentration of dissolved theobromine in sodium benzoate solutions, while thermodynamic properties were analyzed to understand the underlying mechanism. The study discovered that the solubility of theobromine was enhanced by sevenfold in the presence of sodium benzoate. Thermodynamic analysis revealed the solubilization process to be entropy-driven. Additionally, contact angle estimations confirmed increased hydrophobicity with higher sodium benzoate concentration, facilitating the solubilization of theobromine in the aqueous phase. Furthermore, FTIR analysis indicates that the solubilization of the bioactive compound occurs exclusively subsequent to traversing the minimum hydrotropic concentration (MHC).

Unveiling the Anticancer Potential: Computational Exploration of Nitrogenated Derivatives of (+)-Pancratistatin as Topoisomerase I Inhibitors.

Cancer poses a substantial global health challenge, driving the need for innovative therapeutic solutions that offer improved effectiveness and fewer side effects. Topoisomerase I (Topo I) has emerged as a validated molecular target in the pursuit of developing anticancer drugs due to its critical role in DNA replication and transcription. (+)-Pancratistatin (PST), a naturally occurring compound found in various Amaryllidaceae plants, exhibits promising anticancer properties by inhibiting Topo I activity. However, its clinical utility is hindered by issues related to limited chemical availability and aqueous solubility. To address these challenges, molecular modelling techniques, including virtual screening, molecular docking, molecular mechanics with generalised born and surface area solvation (MM-GBSA) calculations, and molecular dynamics simulations were utilised to evaluate the binding interactions and energetics of PST analogues with Topo I, comparing them with the well-known Topo I inhibitor, Camptothecin. Among the compounds screened for this study, nitrogenated analogues emerged as the most encouraging drug candidates, exhibiting improved binding affinities, favourable interactions with the active site of Topo I, and stability of the protein-ligand complex. Structural analysis pinpointed key molecular determinants responsible for the heightened potency of nitrogenated analogues, shedding light on essential structural modifications for increased activity. Moreover, in silico absorption, distribution, metabolism, excretion, and toxicity (ADMET) predictions highlighted favourable drug-like properties and reduced toxicity profiles for the most prominent nitrogenated analogues, further supporting their potential as effective anticancer agents. In summary, this screening study underscores the significance of nitrogenation in augmenting the anticancer efficacy of PST analogues targeting Topo I. The identified lead compounds exhibit significant potential for subsequent experimental validation and optimisation, thus facilitating the development of novel and efficacious anticancer therapeutics with enhanced pharmacological profiles.

Electric-field nanobubbles: A step change in nanobubble engineering, and its “coming of age”

Electric-field nanobubbles: A step change in nanobubble engineering, and its “coming of age” Niall J. English, from Chemical Engineering at University College Dublin, discusses how electric-field nanobubbles have displaced their mechanically-generated counterparts in performance and sustainability. Limited solubility of gases in water, such as oxygen, is a fundamental challenge. In ecosystems and the environment, lack of dissolved oxygen (DO) is a major reason for fish kills and water bodies being blighted by algal blooms, in addition to lack of effectiveness of activated-sludge processes in water treatment or poorer-than-hoped results in irrigation. Nanobubbles (NBs) are tiny gas bubbles on the nanometre (nm) scale. They may be thermodynamically metastable for up to many months, or sometimes even longer, and have enhanced gas-transfer properties and substantial industrial potential. The concept of NBs versus traditional, coarser bubbles – with the latter subject to buoyancy phenomena, while NBs are relatively impervious to rising – in essence, “subverts” Stokes’ Law of bubble rising – and have an excellent area-to-volume ratio. If NBs are generated well – indeed, the art of “nanobubble engineering”, as it were – NBs lead to important and useful applications.

Aliovalent Doping of Niobium and Tantalum Pentoxide as Potential Alternative Support Material for Fuel Cell Catalysts

AbstractAs the usually used Carbon Blacks (CB) as support materials in fuel cell catalysts are thermodynamically unstable, alternative supports with high chemical stability and electrical conductivity are to be found. After the investigation of Nb and Ta‐doped SnO2 in an earlier publication, which revealed interesting conductivity properties, we expanded our portfolio of mutual doping of elements of stable oxides into the oxides of the others by reporting here on the Sn, Hf and W‐doping as guests into the base oxides Nb2O5 and Ta2O5. The changes in unit cell parameters as indicators for the doping success were investigated in the doping range of x=0–10 mol % guest fraction. From a complete solubility of the guest ions in case of Hf and W‐doping in the base oxides to a limited solubility in case of Sn‐doping, a whole spectrum of different results was obtained. Additional insight came from UV/vis spectroscopic investigations in diffuse reflectance as well as electrical conductivity measurements.

Displacement cascade bombardment of delta-hydrides in alpha-zirconium

One of the factors affecting the in-pile performance of Zr-based alloys is the precipitation of hydrides once H concentrations exceed the terminal solubility limit. H transport and hydride precipitation/dissolution is commonly modeled in codes such as BISON, but most of the experimental data supporting these models has been collected on unirradiated materials. As such, there is considerable uncertainty as to the influence of irradiation effects. In this work, molecular dynamics simulations of displacement cascades were performed on δ-hydrides to elucidate: 1) the extent of H dissolution following cascade impacts and 2) any alterations to defect production characteristics when compared to cascades in bulk Zr. The immediate amount of H dissolved in a high-energy cascade impact is notable, but a considerable fraction of the dissolved H atoms are rapidly re-absorbed into the hydride at reactor-relevant temperatures. The amount of dissolved H also decreases with increasing hydride size. When considering the expected volume fractions of hydrides, it is not expected that the irradiation-induced H dissolution rate will significantly affect the availability of H in the Zr lattice. In terms of defect production, cascades which overlap δ-hydrides produced an order of magnitude more stable defects than equivalent-energy cascades in bulk Zr. Vacancy defects are predominantly contained within the hydride structure while interstitials clusters are found adjacent to the hydride surface. Interstitials are strongly repelled by the hydride structure which may drive the expulsion of cascade-generated interstitials to the hydride surface and impede athermal recombination. Thus, the interatomic potential used in this work predicted a significant alteration to the defect survival efficiency and a stark production bias in the availability of mobile defects in bulk Zr following hydride-overlapped displacement cascades.

Silver carp swim bladder collagen derived from deep eutectic solvents: Enhanced solubility against pH and NaCl stresses

Deep eutectic solvents (DESs) are renowned in chemical and food industries for their eco-friendly extraction efficacy. Silver carp swim bladders, a collagen-rich byproduct of surimi production, are underutilized, resulting in considerable protein waste. Traditionally, collagen extraction has relied on harsh acids, contributing to environmental pollution and producing collagens with limited solubility, thus constraining their applications. This study evaluated DESs compared to conventional acids in extracting collagen, focusing on structural and solubility variations. Notably, urea-based DESs (urea-lactic acid: U-LA, 1:10, w/v) achieved the highest hydroxyproline recovery rates (∼ 94 %), comparable to acetic acid (AA, 1:20, w/v), but with half the solid-liquid ratio. Unlike acid-extracted collagen, which preserved the triple-helical structure, urea-based DESs partially disrupted this configuration by reducing intramolecular hydrogen bonding within collagen. However, these solvents simultaneously increased intermolecular hydrogen bonding. This alteration significantly enhanced collagen's solubility, maintaining over 60 % across a broad pH range (1−10) and various NaCl concentrations (0–6 %, w/v). Furthermore, urea-acetic acid (U-AA) extracted collagen exhibited the highest maximum transition temperature (solid state, Tmax = 101.94 °C) and gel strength (165 g). The findings suggest that urea-based DESs not only enhance collagen recovery rates but also its solubility and gelation properties, broadening its potential applications in cosmetics, food products, and biomaterials.

Trivacant Keggin-type polyoxometalate/TiO2 composite for enhanced sonocatalytic degradation of AR88 from aqueous solutions

Polyoxometalates (POMs) have been limited in their widespread use in catalysis in previous studies due to their strong carrier complexation and limited solubility. To overcome this limitation, in this study, Z-type heterojunction composites constructed with trivacant Keggin-type POMs K9SbW9O33·19.5H2O and TiO2 were synthesized by the sol–gel method and used for the sonocatalytic removal of the organic pollutant AR88. The results showed that, compared with pure K9SbW9O33·19.5H2O, the optimum K9SbW9O33·19.5H2O/TiO2 showed a significantly higher sonocatalytic degradation efficiency of 87.2 % for AR88, and the mineralization rate reached 51.8 %. Parameters such as dye pH and sonication power were optimized to determine the best conditions for sonocatalysis. In addition, the K9SbW9O33·19.5H2O/TiO2 Z-type heterojunction composites showed good stability and reusability. The excellent catalytic performance is attributed to the effective separation of charges and holes by the Z-type heterojunction, which enables them to produce active substances for AR88 decomposition. This study demonstrates the high potential of POMs for the application of sonocatalysis in the treatment of organic pollutants.

Co-sorption of volatile components in polymer-based pharmaceutical formulations

Amorphous Solid Dispersions (ASDs) are mixtures of active pharmaceutical ingredients (APIs) and polymers aiming to increase API aqueous solubility and bioavailability. ASDs are often produced using solvent-based manufacturing, such as spray drying. Due to solubility or miscibility limitations in one solvent, solvent mixtures are frequently used for this purpose. Drying solvents or solvent mixtures from polymer-based products like ASDs is an energy-intensive and time-consuming process. Designing and optimising this drying process requires knowledge of the sorption isotherms of the solvent(s) in these polymer-based products. In this work, we developed a novel approach for measuring the simultaneous absorption/desorption of two solvents in a polymer. Combining classical dynamic vapour sorption (DVS) measurements with Raman spectroscopy, this innovative approach provides a more detailed and accurate measurement of the sorption isotherms than common methods. Moreover, we developed an approach for precisely predicting the sorption equilibria in three-component systems just based on sorption data of the corresponding binary subsystems. Our modelling approach combines the Perturbed-Chain Statistical Associating Fluid Theory (PC-SAFT) with the Non-Equilibrium Thermodynamics of Glassy Polymers (NET-GP). Building on the description of the sorption isotherms of either water or ethanol in poly(vinylpyrrolidone-co-vinyl acetate) (PVPVA64) and in indomethacin (IND), we were able to quantitatively predict the simultaneous sorption of water and ethanol in PVPVA64 and the one of ethanol in an IND/PVPVA64 ASD.

Experimental demonstration of the production of poly(oxymethylene) dimethyl ethers from methanolic formaldehyde solutions in a closed-loop mini-plant

Poly(oxymethylene) dimethyl ethers of chain length 3–5 ( ▪ ) are discussed as synthetic diesel fuels due to their potential to significantly reduce soot emissions while presenting physicochemical properties similar to conventional diesel fuels. A recently developed process to produce ▪ directly from methanol and aqueous formaldehyde is a promising way to avoid expensive intermediates such as trioxane, methylal, or dimethyl ether. The process consists of a reactor, a distillation sequence, and a membrane unit. The first distillation column is particularly challenging due to the reactive character of the separation, the high number of components present, and the limited solubility of formaldehyde. Up to now, the feasibility of this separation has yet to be demonstrated. This work presents closed-loop experiments in a demonstration plant erected at the Campus Straubing of the Technical University of Munich with closing recycle. In the distillation step, ▪ with very small impurities of around 800 ppm of formaldehyde was obtained. The experimental results were compared with simulations based on a reactive equilibrium stage model. The simulations of the temperature and composition profiles for the majority of the components are in line with the experiments. Although the membrane separation exhibited weaker water selectivity than in previous tests, it was sufficient to overcome distillation boundaries. Additionally, this study assesses the potential for solid precipitation, explores trade-offs in product quality, and discusses overall mass balances of the process, demonstrating the overall feasibility of the process.

A Review on Recent Trends in Photo-Drug Efficiency of Advanced Biomaterials in Photodynamic Therapy of Cancer.

Photodynamic Therapy (PDT) has emerged as a highly efficient and non-invasive cancer treatment, which is crucial considering the significant global mortality rates associated with cancer. The effectiveness of PDT primarily relies on the quality of the photosensitizers employed. When exposed to appropriate light irradiation, these photosensitizers absorb energy and transition to an excited state, eventually transferring energy to nearby molecules and generating Reactive Oxygen Species (ROS), including singlet oxygen [1O2]. The ability to absorb light in visible and nearinfrared wavelengths makes porphyrins and derivatives useful photosensitizers for PDT. Chemically, Porphyrins, composed of tetra-pyrrole structures connected by four methylene groups, represent the typical photosensitizers. The limited water solubility and bio-stability of porphyrin photosensitizers and their non-specific tumor-targeting properties hinder PDT effectiveness and clinical applications. Therefore, a wide range of modification and functionalization techniques have been used to maximize PDT efficiency and develop multidimensional porphyrin-based functional materials. Recent progress in porphyrin-based functional materials has been investigated in this review paper, focusing on two main aspects including the development of porphyrinic amphiphiles that improve water solubility and biocompatibility, and the design of porphyrin-based polymers, including block copolymers with covalent bonds and supramolecular polymers with noncovalent bonds, which provide versatile platforms for PDT applications. The development of porphyrin-based functional materials will allow researchers to significantly expand PDT applications for cancer therapy by opening up new opportunities. With these innovations, porphyrins will overcome their limitations and push PDT to the forefront of cancer treatment options.

Limited dissolution of transition metals in the nanocrystalline cerium (IV) oxide

Nanocrystalline cerium (IV) oxides doped with transition metals have gained significant interest recently, mostly in the field of catalysis. Herein, we present the comprehensive studies on ceria doped with 10 mol.% of transition metals (Mn, Fe, Co, Ni or Cu) synthesized by the reverse microemulsion method. The aim of this work is to study the properties of those materials with the use of different complementary methods like XRD, SEM, TPR, and XPS and to determine the possibility of fabrication of single-phase materials with that doping level. Studies presented here prove that despite showing single-phase XRD patterns with high nanocrystallinity, in all obtained materials, the dopants are not fully incorporated in the ceria lattice. Spectroscopy studies show that additional transition metal oxides are present on the surface of all materials. Herein, we also present the analyses of L3,2-edges of transition metals in ceria, as well as high energy Ce K-edge to prove that 10 mol.% of any of those transition metals cannot be incorporated in the ceria host without the formation of additional phases. Using techniques presented here, it was found that the highest share of Mn can be dissolved in the lattice, while Cu is mostly present as a surficial Cu2O. Studies presented are an important contribution to the discussion about the solubility limits in nanocrystalline ceria and its properties which may be utilized for e.g various catalysts or as electrolytes.