Degree Of Solubilization Research Articles

Assessing the potential of olive mill solid waste as feedstock for methane and volatile fatty acids production via anaerobic bioprocesses

The extensive production of olive mill solid waste (OMSW) from olive oil industry in the Mediterranean basin claims effective treatments and valorization strategies. This study aims to elucidate the potential of anaerobic digestion (AD) and anaerobic fermentation (AF) to convert pre-treated OMSW into biogas (CH4) and volatile fatty acids (VFA), respectively. The two thermal treatment conditions (65 °C and 180 °C) that are being implemented in the industry that manages the OMSW were tested. Comparing the two treatments aims to demonstrate the influence on the AD process of the degree of solubilization and degradation of the metabolites produced from the same substrate. AD of OMSW treated at low-temperature (65 °C) exhibited similar methane yields (195 ± 8 mL CH4/g volatile solid (VS)) to raw OMSW. AD of the solid phase (SP) after high-temperature treatment with acid addition at 180 °C resulted in methane yields comparable to raw OMSW while the liquid phase (LP) exhibited low methane yields (85 ± 10 mL CH4/g VS). Nevertheless, LP/180 °C exhibited the highest VFA bioconversion at 27.6 %, compared to less than 10 % for SP/180 ºC, SP/65 °C, and raw OMSW. The VFA profile showed notable variations with thermal treatment temperatures. Propionic acid dominated at SP/65 °C, while acetic acid became the primary VFA at 180 °C. Furthermore, significant degradation rates of phenolic compounds and furans were observed during the final day of both anaerobic processes. Overall, these findings suggest that AD is more suitable for raw OMSW, treated at low temperature and SP at high temperature, while AF offers a promising alternative for high-temperature-treated LP.

The Interaction Of Homodimer Styrylcyanine Dyes With Sodium Dodecyl Sulfate And Triton X-100.

Solubilization of the styrylcyanine dye Sbt ((E)-2-(4-(dimethylamino)styryl)-3-methylbenzo[d]thiazol-3-ium iodide) and its homodimers Dbt-5 and Dbt-10 in aqueous solution of sodium dodecyl sulfate and Triton X-100 has been studied by steady state and picosecond time-resolved fluorescence spectroscopy. At low concentration of sodium dodecyl sulfate in solution, between Sbt, Dbt-5 dyes molecules and surfactant ion pairs are formed followed by the formation non-luminescent H-aggregates. The nature of the interaction between molecules of dyes and surfactants has been revealed. The binding constants Ks of the dyes to the surfactants, free energy changes (ΔG0), the number of dye molecules (n) included in a single micelle and photophysical parameters have been determined. The degree of solubilization of dyes in micellar solution of Triton X-100 is higher as compared to sodium dodecyl sulfate and depends on the molecular weight and size of both dye molecules and micelles.

Physicochemical investigations of nootropic drug piracetam for enhanced solubilization as nano drug carrier under the influence of single and mixed micellar formulations: An optimized approach towards drug delivery

Nonionic surfactants have drawn tremendous attention for micellar solubilization, sustained release of the drug, encapsulation of pharmaceutically active ingredients, and permeabilization due to their distinct physicochemical characteristics. Concise solubility investigations are required for the appropriate selection of nonionic surfactant that is to be used for a formulation. In the present research, a cluster of micelles was developed that relies on trapping and stabilizing piracetam by balancing the hydrophilic and hydrophobic forces of nonionic surfactants. Tween 80 and Triton-X 100 and a mixture of these surfactants were used to clarify the drug-surfactant interaction in an aqueous and micellar medium. The interaction was investigated in premicellar, micellar, and post-micellar regions by using UV/Visible spectroscopy. Spectroscopic parameters were calculated to determine the degree of solubilization in terms of the partition coefficient (Kx), binding constant (Kb), and their respective energies in terms of Gibbs free energy of partition (ΔGp) and Gibbs free energy of binding (ΔGb) for piracetam. The solubilization of piracetam is enhanced by mixing an adequate amount of both nonionic surfactants. The obtained results demonstrated that solubilization is spontaneous and entropically favorable and the cluster of micelles in both single and mixed micellar mediums are stable due to the presence of a much more hydrophobic and hydrophilic culture which provides a synergistic link between the two surfactants.

Effect of TX-100 on solubilizing power of CTAB and CPC for H Acid: An experimental and computational analysis

The present research work investigates the solubility of an anionic dye 8-amino-1-naphthol-3,6-disulfonic acid (H Acid) within the micellar mediaof two cationic surfactants cetylpyridinium chloride (CPC) and cetyltrimethylammonium bromide (CTAB) as well as in the mixed micellar mediaof each cationic surfactant with Triton X-100 (TX-100). The data from differential absorption spectroscopy across a concentration range spanning from pre-micellar to post-micellar regions was used to determine the degree of solubilization by calculating the partition coefficient (Kx), binding constant (Kb) and Gibbs free energy associated with the relevant processes. Electrical conductivity of each cationic surfactant in the presence of H Acid was recorded in aqueous media and used to determine the CMC and subsequent thermodynamic parameters including entropy (ΔSm), enthalpy (ΔHm) and Gibbs free energy change (ΔGm) associated with the process of micellization. The computational analysis was carried out with GAUSSIAN 09 using a 6-311G + basis set with a DFT/ B3LYP hybrid approach and each set of energy minimization was executed to perform frequency calculations for Frontier molecular orbital analysis and to evaluate absorption spectra. Moreover, the molecular electrostatic potential surfaces (MESP) were also computed to find their suitable hydrophobic and hydrophilic interactions.

The Use of Hydrodynamic Cavitation to Improve the Anaerobic Digestion of Waste from Dairy Cattle Farming—From Laboratory Tests to Large-Scale Agricultural Biogas Plants

There is a need to find methods to intensify the anaerobic digestion process. One possibility is the use of pretreatment techniques. Many laboratory tests confirm their effectiveness, but in most cases, there is no verification work carried out on industrial plants. A reliable and complete evaluation of new solutions can only be carried out in plants that reflect operating conditions at a higher readiness technological level. This has a direct impact on the scientific value and, above all, on the high application value of innovative technologies. The aim of our research carried out under laboratory conditions and on a large scale was to determine the technological and energy efficiency of the use of hydrodynamic cavitation in the pretreatment of a waste mixture from dairy farms. It has been shown that hydrodynamic cavitation significantly increases the concentration of organic compounds in the dissolved phase. In the most effective variants, the increase in the content of these indicators was over 90% for both COD and TOC. The degree of solubilisation achieved was 49 ± 2.6% for COD and almost 52 ± 4.4% for TOC. Under laboratory conditions, the highest effects of anaerobic digestion were achieved after 10 min of pretreatment. The amount of biogas was, on average, 367 ± 18 mL/gCOD, and the amount of methane was 233 ± 13 mL/gCOD. Further large-scale optimisation trials showed that after 8 min of hydrodynamic cavitation, the biogas yield was 327 ± 8 L/kgCOD with a CH4 content of 62.9 ± 1.9%. With this variant, the net energy yield was 66.4 ± 2.6 kWh/day, a value that was 13.9% higher than the original variant with 10 min of disintegration and 3.1% higher than the variant without pretreatment.

Application of Hydrodynamic Cavitation in the Disintegration of Aerobic Granular Sludge—Evaluation of Pretreatment Time on Biomass Properties, Anaerobic Digestion Efficiency and Energy Balance

The use of aerobic granular sludge is a promising and future-proof solution for wastewater treatment. The implementation of this technology requires the development of efficient and cost-effective methods for the management of excess sludge. The aim of the research was to evaluate the effects of hydrodynamic cavitation on the efficiency of aerobic granular sludge digestion. Respirometric measurements were performed at a temperature of 38 °C and an initial organic load of 5.0 gVS/L. The changes in the properties of the pretreated biomass, the kinetics of methane fermentation, the amount and composition of the biogas produced, and an energetic evaluation of the process were carried out. A significant influence of hydrodynamic cavitation on the transfer of organic compounds into the dissolved phase was demonstrated. The degree of solubilisation was 37% for COD and 42% and for TOC. The efficiency of CH4 production from the pretreated sludge reached a value of 496 ± 12 mL/gVS, which corresponds to an increase of 19.6% compared to the raw biomass. The influence of cavitation on the CH4 content of the biogas was not observed. Strong correlations were found between the efficiency of anaerobic digestion and the concentration of dissolved organic compounds and the hydrodynamic cavitation time used. The gross energy yield was closely correlated with the amount of CH4. The highest comparable values of 3.12 Wh/gTS to 3.18 Wh/gTS were found in the variants in which the hydrodynamic cavitation (HC) time was between 15 min and 50 min. The highest net energy production of 2890 kWh/MgTS was achieved after 15 min of pretreatment.

Enhancing anaerobic digestion of dewatered sewage sludge through thermal hydrolysis pretreatment: Performance evaluation and microbial community analysis

This study explored the effectiveness of thermal hydrolysis (TH) in conditioning dewatered sewage sludge (DSS) for enhanced anaerobic digestion (AD). The TH pretreatment employed in this study (30 min at 170°C and 6 bar) significantly improved the bioavailability of DSS. The degree of solubilization varied with the physicochemical characteristics of DSS collected over three seasons: 16.8–24.8% on a volatile solids (VS) basis and 9.4–33.7% on a chemical oxygen demand (COD) basis. Correspondingly, the dissolved fraction of VS in DSS increased by 2.1–3.4-fold, and the soluble fraction of COD rose by 1.4–2.9-fold. The duplicate anaerobic reactors treating the TH-pretreated DSS did not achieve steady-state operation at the intended design organic loading rate (OLR) of 3.8 g VS/L·d, but showed stable performance at an OLR of 3.4 g VS/L·d with significantly higher methane yield (0.26–0.29 L/g VS fed) and VS removal (35–38%) than those reported for untreated DSS and comparable to TH-pretreated DSS. The reactors' microbial community structures changed dynamically as the OLR varied, with shifts in dominance between acetoclastic and hydrogenotrophic methanogens. The results highlight the promising potential of TH-AD process for efficiently treating DSS while emphasizing the importance of optimizing OLR for stable operation.

Processing of hemicellulose in wheat straw by steaming and ultrafiltration – A novel approach

Water-soluble xylans useable for many potential applications can be produced based on the hydrolysis of wheat straw within a fixed bed using saturated steam to provide a xylan-rich hydrolysate low in particles and lignin enabling an effective ultrafiltration and xylan separation. Under defined conditions (180 °C, 10 bar, 35 min), a degree of solubilization of 29.6 % for straw and of 63 % for hemicellulose is achieved. The dry mass of the resulting hydrolysate consists of at least 58 % xylose and arabinose. The xylose is mainly (87 %) present in non-monomeric form and appears to have a broad molecular weight distribution. Ultrafiltration with commercial membranes (4 to 50 kDa) is being investigated for the separation of the target fraction; here significant differences in the filtration behavior and rejections from 9 to 81 % for carbohydrates and from 13 to 48 % for phenolic compounds (lignin), respectively, are found.

Solubilization and partitioning study of nickel fluoride complex [Ni(dmen)2F2].8H2O in the micellar media of sodium stearate by conductometric and spectroscopic techniques

This study was aimed to investigate the physicochemical behavior, solubilization and interaction of coordination complex [Ni(dmen)2F2].8H2O (NDC) with anionic surfactant sodium stearate (SS). The thermodynamic parameters of solubilization such as standard free energy (ΔGm0), enthalpy (ΔHm0) and entropy (ΔSm0) changes of micellization were evaluated by using conductometric measurements. These parameters revealed that the phenomenon of micellization is entropy driven and spontaneous due to the more negative value of (ΔGm0). The quantitative estimation of partitioning parameters such as partition coefficient (Kx), binding constant (Kb), standard energy of partition (ΔGpartO), and standard binding energy (ΔGbindO) revealed the complex-surfactant interaction. Spectroscopic study indicated the high degree of interaction and solubilization of NDC in SS micellar media.. The partitioning results not only governs the mechanism of solubilization but also gives understanding about the partitioning of NDC across membranes in biological systems.

Development of a Primary Sewage Sludge Pretreatment Strategy Using a Combined Alkaline–Ultrasound Pretreatment for Enhancing Microbial Electrolysis Cell Performance

Ultrasound and combined alkaline–ultrasound pretreatment (AUP) strategies were examined for primary sewage sludge (SS) disintegration and were utilized to evaluate the degree of solubilization (DS). Further, the pretreated primary SS was operated in microbial electrolysis cells (MECs) to maximize methane production and thereby improve the reactor performance. The highest DS of 67.2% of primary SS was recorded with the AUP. MEC reactors operated with the AUP showed the highest methane production (240 ± 6.4 mL g VSin−1). VS (61.1%) and COD (72.2%) removal in the MEC ALK-US showed the best organic matter removal efficiency. In the modified Gompertz analysis, the substrate with the highest degree of solubilization (AUP) had the shortest lag phase (0.2 ± 0.1 d). This implies that forced hydrolysis via pretreatment could enhance biodegradability, thereby making it easy for microorganisms to consume and leading to improved MEC performances. Microbial analysis implicitly demonstrated that pretreatment expedited the growth of hydrolytic bacteria (Bacteroidetes and Firmicutes), and a syntrophic interaction with electroactive microorganisms (Smithella) and hydrogenotrophic methanogens (Methanoculleus) was enriched in the MECs with AUP sludge. This suggests that the AUP strategy could be useful to enhance anaerobic digestion performance and provide a new perspective on treating primary SS in an economical way.

Improving properties of baricitinib due to interaction with Pluronic micelles

Baricitinib is a new generation medicinal compound that has been recommended for the treatment of rheumatoid arthritis in 2017 as well as alopecia areata and COVID-19 in 2022. The use of baricitinib is complicated by its poor aqueous solubility and unwanted side effects. Therefore, the aim of this work is an improvement of the baricitinib solubility using Pluronic micelles. The effect of the micelles on the solubility and membrane permeability of baricitinib is revealed using the isothermal saturation method and the Franz diffusion cell, respectively. It was observed that degree of baricitinib solubilization depends on the Pluronics structure and pH. The regularities of the interaction of the drug with the micelles were established by means of light scattering and 1D and DOSY 1H NMR. It was demonstrated that the ionization state of baricitinib, depending on pH, affects the drug ability to be included in the micelles. The most effective solubilizer of baricitinib among the Pluronics under study was proposed. The data obtained may be useful for the development of water-soluble formulations of baricitinib.

Comparative study of acid- and alkali-catalyzed 1,4-butanediol pretreatment for co-production of fermentable sugars and value-added lignin compounds

BackgroundOrganosolv pretreatment is one of the most efficient methods for delignification and boosting biomass saccharification. As compared to typical ethanol organosolv pretreatments, 1,4-butanediol (BDO) organosolv pretreatment is a high-boiling-point solvent pretreatment, which can generate low pressure in the reactor during high temperature cooking that improves the operation safety. Although several studies showed that organosolv pretreatment can lead to effective delignification and enhancement in glucan hydrolysis, there has been no studies on acid- and alkali-catalyzed BDO pretreatment, as well as their comparison on promoting biomass saccharification and lignin utilization.ResultsIt was shown that BDO organosolv pretreatment was more effective in removing lignin from poplar as compared with typical ethanol organosolv pretreatment under the same pretreatment conditions. HCl-BDO pretreatment with 40 mM acid loading led to 82.04% of original lignin removed from biomass, as compared to the lignin removal of 59.66% in HCl-Ethanol pretreatment. Besides, acid-catalyzed BDO pretreatment was more effective in improving the enzymatic digestibility of poplar than alkali-catalyzed BDO pretreatment. As a result, HCl-BDO with acid loading of 40 mM provided a good enzymatic digestibility of cellulose (91.16%) and the maximum sugar yield of 79.41% from original woody biomass. The linear correlations between physicochemical structure (e.g., fiber swelling, cellulose crystallinity, crystallite size, surface lignin coverage and cellulose accessibility) changes of BDO pretreated poplar and enzymatic hydrolysis were plotted to figure out the main factors that influenced biomass saccharification. Moreover, acid-catalyzed BDO pretreatment mainly brought about the phenolic hydroxyl (PhOH) groups formation in lignin structure, while alkali-catalyzed BDO pretreatment mostly led to the lower molecular weight of lignin.ConclusionsResults indicated that the acid-catalyzed BDO organosolv pretreatment could significantly improve enzymatic digestibility of the highly recalcitrant woody biomass. The great enzymatic hydrolysis of glucan resulted from increased cellulose accessibility, which mostly associated with the higher degree of delignification and hemicellulose solubilization, as well as the more increase in fiber swelling. Besides, lignin was recovered from the organic solvent, which could be used as natural antioxidants. The formation of phenolic hydroxyl groups in lignin structure and the lower molecular weight of lignin contributed to its greater radical scavenging capacity.

Effects of hydrothermal pre-treatment on methane potential of anaerobic digestion sludge cake of cattle manure containing sawdust as bedding materials.

The purpose of this study was to analyze the effect of the hydrothermal pretreatment of anaerobic digestion sludge cake of cattle manure on the solubilization of organic matter and the methane yield in order to improve the anaerobic digestion efficiency of cattle manure collected from the sawdust pens of cattle. Anaerobic digestion sludge cake (ADSC) of cattle manure was thermally pre-treated at 160, 180, 200, and 220°C by the hydrothermal pressure reactor, and the biochemical methane potential of ADSC hydrolysate was analyzed. Methane yield recovered by the hydrothermal pre-treatment of ADCS was estimated based on mass balance. The COD solubilization degree (CODs) of the hydrothermal hydrolysate increased to 63.56, 67.13, 70.07, and 66.14% at the hydrothermal reaction temperatures of 160, 180, 200, and 220 °C, respectively. Considering the VS content obtained after the hydrothermal pretreatment, the methane of 10.2 Nm3/ton-ADSC was recovered from ADSC of 1.0ton, and methane yields of ADSC hydrolysate increased to 15.6, 18.0, 17.4, and 17.2 Nm3/ton-ADSC. Therefore, the optimal hydrothermal reaction temperature that yielded the maximum methane yield was 180 °C based on mass balance, and the methane yield from cattle manure containing sawdust was improved by the hydrothermal pre-treatment of ADSC.

Solid-State Formation of a Potential Melphalan Delivery Nanosystem Based on β-Cyclodextrin and Silver Nanoparticles.

Melphalan (Mel) is an antineoplastic widely used in cancer and other diseases. Its low solubility, rapid hydrolysis, and non-specificity limit its therapeutic performance. To overcome these disadvantages, Mel was included in β-cyclodextrin (βCD), which is a macromolecule that increases its aqueous solubility and stability, among other properties. Additionally, the βCD-Mel complex has been used as a substrate to deposit silver nanoparticles (AgNPs) through magnetron sputtering, forming the βCD-Mel-AgNPs crystalline system. Different techniques showed that the complex (stoichiometric ratio 1:1) has a loading capacity of 27%, an association constant of 625 M-1, and a degree of solubilization of 0.034. Added to this, Mel is partially included, exposing the NH2 and COOH groups that stabilize AgNPs in the solid state, with an average size of 15 ± 3 nm. Its dissolution results in a colloidal solution of AgNPs covered by multiple layers of the βCD-Mel complex, with a hydrodynamic diameter of 116 nm, a PDI of 0.4, and a surface charge of 19 mV. The in vitro permeability assays show that the effective permeability of Mel increased using βCD and AgNPs. This novel nanosystem based on βCD and AgNPs is a promising candidate as a Mel nanocarrier for cancer therapy.

Optimizing Dacarbazine Therapy: Design of a Laser-Triggered Delivery System Based on β-Cyclodextrin and Plasmonic Gold Nanoparticles.

Dacarbazine (DB) is an antineoplastic drug extensively used in cancer therapy. However, present limitations on its performance are related to its low solubility, instability, and non-specificity. To overcome these drawbacks, DB was included in β-cyclodextrin (βCD), which increased its aqueous solubility and stability. This new βCD@DB complex has been associated with plasmonic gold nanoparticles (AuNPs), and polyethylene glycol (PEG) has been added in the process to increase the colloidal stability and biocompatibility. Different techniques revealed that DB allows for a dynamic inclusion into βCD, with an association constant of 80 M-1 and a degree of solubilization of 0.023, where βCD showed a loading capacity of 16%. The partial exposure of the NH2 group in the included DB allows its interaction with AuNPs, with a loading efficiency of 99%. The PEG-AuNPs-βCD@DB nanosystem exhibits an optical plasmonic absorption at 525 nm, a surface charge of -29 mV, and an average size of 12 nm. Finally, laser irradiation assays showed that DB can be released from this platform in a controlled manner over time, reaching a concentration of 56 μg/mL (43% of the initially loaded amount), which, added to the previous data, validates its potential for drug delivery applications. Therefore, the novel nanosystem based on βCD, AuNPs, and PEG is a promising candidate as a new nanocarrier for DB.

Application of anionic-nonionic mixed micellar system for solubilization of methylene blue dye

Present study highlights the interaction of methylene blue (MB), a cationic dye, with anionic surfactant, sodium dodecyl sulfate (SDS), and its mixed micelles with a nonionic surfactant Triton X-114 (TX-114). The results obtained from UV–visible spectrophotometry were used to obtain the degree of solubilization in terms of binding constant (Kb) and partition coefficient (Kx) of dye in single and mixed micellar systems (MMS). Gibb’s free energies of partitioning and binding were also calculated for both systems. Specific conductance was measured to determine the CMC of single and mixed micellar media at five different temperatures, T = (293.15 – 333.15) K. Temperature-dependent thermodynamic parameters like Gibb’s free energy of micellization (ΔGomic), enthalpy of micellization (ΔHomic), and entropy of micellization (ΔSomic) were calculated using data of specific conductance measurements. Effect of concentration of TX-114 on Kx and Kb values of the MB in MMS is also investigated. Spectroscopic and conductometric results revealed that the anionic-nonionic mixed micellar system was better and more effective for the removal and solubilization of MB from aqueous system as compared to anionic micelles only. However, it has been observed that after a critical concentration an increase of non-ionic surfactant concentration has a reverse effect on solubilizing power of ionic-nonionic mixed micellar system. This indicates that the dye-surfactant interaction became weaker due to possible decrease in ionic character of mixed micelles when the high fraction of TX-114 was used.

Accelerated stabilization of high solid sludge by thermal hydrolysis pretreatment in autothermal thermophilic aerobic digestion (ATAD) process.

Autothermal thermophilic aerobic digestion (ATAD) is a rapid biological treatment technology for sludge stabilization. To improve digestion efficiency and shorten stabilization time, thermal hydrolysis pretreatment was employed before ATAD of high solid sludge. The results showed that accelerated stabilization of high solid sludge (total solid=10.1%) was achieved by thermal hydrolysis pretreatment with volatile solid removal efficiency of 40.3% after 8 days of ATAD, 11 days earlier than unpretreated sludge. The enhanced release and hydrolysis of intracellular organics resulted in a solubilization degree of 45.3%. The reduced sludge viscosity and improved fluidity after thermal hydrolysis facilitated mixing, aeration and organics degradation during ATAD. Excitation emission matrix analysis indicated that the fluorescence intensity of soluble microbial byproduct and tyrosine-like protein increased markedly after thermal hydrolysis and decreased after ATAD. The proportion of high molecular weight (MW>10kDa) substances in the supernatant increased significantly after thermal hydrolysis, while the low MW (MW<1kDa) substances decreased after ATAD. The significant difference in microbial composition between the pretreatment and control groups elucidated the accelerated sludge stabilization under thermal hydrolysis. This work provides an efficient and practical strategy to achieve rapid stabilization of high solid sludge.

Release of Ropinirole in Acrylate Transdermal Patches: Mutual Interactions Between Formulation Variables

The aim of this study is to evaluate the cooperative interactions between formulation variables of ropinirole transdermal patches and characterize the effects of drug loading and crystallinity, degree of ionization and drug-polymer solubilization, functionalization of acrylate polymeric basis, and the addition of permeation enhancers over the release profiles. Several series of transdermal films based on carboxylic or hydroxylic acrylates (DuroTak®) and containing 1 to 10% ropinirole hydrochloride were laminated by mold-casting and evaporation. Formulations were characterized for crystallinity, drug particle size, drug assay, and residual solvents. Release profiles were obtained at different drug ionization state using paddle over disk apparatus. Mechanisms were elucidated with nonlinear data fitting of relevant release equations. Fickian and erosion processes were evaluated with the Peppas–Sahlin equation, and burst release risks were estimated as an independent term added to Higuchi kinetics. X-ray diffraction and microscopy evidenced differences in drug-polymer solubilization and density of drug crystals. Concerning drug release, area under the curve of dissolved quantities and release percentage were discriminant variables in mutual influence. Peppas–Shalin equation was the majority descriptor of release suggesting a combination of Fickian and erosion processes, revealing a decrease in the Fickian component as drug loading increased. Major burst release risks were evidenced mostly with Higuchi kinetics with vinylacetate acrylates. The carboxylic polymer without vinylacetate provided the best release extent, being more highly efficient as lower the drug loading was. Permeation enhancers with carboxylic or aliphatic radicals have, additionally, modified the release properties of ropinirole. Chemical interactions between the drug and acrylic polymers have been demonstrated. Only the effect with carboxylic polymer is pH dependent. The vinyl acetate comonomer reduces the drug release rate most effectively in formulations with low drug loads. The acrylic polymers without vinylacetate achieved the highest drug solubilization and thus the highest degree of release, providing a release of approximately 15% of the drug load.

Encapsulation of ethyl violet by anionic-cationic mixed micellar solution: Spectroscopic and conductometric studies

Organic dyes are extensively used in various industries i.e. textile. Their hydrophobicity is the main bottleneck in their applications, where the dispersion medium is water. The poor solubility of such colorants is addressed by the addition of different surfactants, but none of the single surfactants proved fully satisfactory so far. Herein, different formulations of anionic and cationic surfactants (SDS, SDBS, CTAB, and TTAB) have been employed to enhance the solubility and stability of a cationic dye, ethyl violet (EV). Spectrophotometric data helped to calculate the values of the partition coefficient (K x ), binding constant (K b ), and Gibbs energies of respective processes. The said parameters are indicators of the degree of solubilization which were calculated at 298.15 K. The data of specific conductance was utilized to estimate critical micelle concentration (CMC) and to calculate thermodynamic parameters; Gibbs energy (ΔG m ), entropy (ΔS m ), and enthalpy (ΔH m ) of micellization for surfactants in the presence of dye at different temperatures (303.15–318.15 K). The obtained results from both techniques revealed the spontaneous nature of micellization and solubilization. Furthermore, the binding and partitioning ability of mixed micellar media came out to be significantly different than that of the solo surfactant system due to the synergistic effect of cationics on micellar media of anionics. It shows how dye is lying inside the SDS and SDBS micelle. • Locus of incorporated dye is near water-micelle interface. • Charge density of a micelle governs its solubilizing efficacy. • Mixing of different surfactants has a synergistic effect on solubilizing power.

Impact of Simulated Intestinal Fluids on Dissolution, Solution Chemistry, and Membrane Transport of Amorphous Multidrug Formulations.

The solution behavior and membrane transport of multidrug formulations were herein investigated in a biorelevant medium simulating fasted conditions. Amorphous multidrug formulations were prepared by the solvent evaporation method. Combinations of atazanavir (ATV) and ritonavir (RTV) and felodipine (FDN) and indapamide (IPM) were prepared and stabilized by a polymer for studying their dissolution (under non-sink conditions) and membrane transport in fasted state simulated intestinal fluid (FaSSIF). The micellar solubilization by FaSSIF enhanced the amorphous solubility of the drugs to different extents. Similar to buffer, the maximum achievable concentration of drugs in combination was reduced in FaSSIF, but the extent of reduction was affected by the degree of FaSSIF solubilization. Dissolution studies of ATV and IPM revealed that the amorphous solubility of these two drugs was not affected by FaSSIF solubilization. In contrast, RTV was significantly affected by FaSSIF solubilization with a 30% reduction in the maximum achievable concentration upon combination to ATV, compared to 50% reduction in buffer. This positive deviation by FaSSIF solubilization was not reflected in the mass transport–time profiles. Interestingly, FDN concentrations remain constant until the amount of IPM added was over 1000 μg/mL. No decrease in the membrane transport of FDN was observed for a 1:1 M ratio of FDN-IPM combination. This study demonstrates the importance of studying amorphous multidrug formulations under physiologically relevant conditions to obtain insights into the performance of these formulations after oral administration.