Micellar Systems Research Articles

Molecular insights into fragrance release from SDS and SLES micelles

Understanding the interaction between fragrance and surfactant micelles is essential for formulators to develop performing fragrant products. The equilibrium of fragrances in micellar solution of two commonly used surfactants in home and body care industries, namely sodium dodecyl sulphate (SDS) and sodium lauryl ether sulphate (SLES), has been investigated. The difference between SDS and SLES in the release of fragrant compounds is assessed by headspace measurements and explained at a molecular level by the different solubilization sites of the perfume within the micellar systems. Diffusion-Ordered Nuclear Magnetic Resonance Spectroscopy (DOSY NMR) shows that SLES micelles solubilize less fragrance than SDS. Subsequently, a shift from fragrance positioning through the water phase from SDS to SLES system is shown with COSMOmic calculations. This study brings knowledge on fragrance/surfactant interactions and shows the interest of using a computational method to screen and compare fragranced surfactants systems allowing formulators to anticipate the performance of their products.

Transfer of ANS-Like Drugs from Micellar Drug Delivery Systems to Albumin Is Highly Favorable and Protected from Competition with Surfactant by "Reserved" Binding Sites.

Micellar drug delivery systems (MDDS) for the intravenous administration of poorly soluble drugs have great advantages over alternative formulations in terms of the safety of their excipients, storage stability, and straightforward production. A classic example is mixed micelles of glycocholate (GC) and lecithin, both endogenous substances in human blood. What limits the use of MDDS is the complexity of the transitions after injection. In particular, as the MDDS disintegrate partially or completely after injection, the drug has to be transferred safely to endogenous carriers in the blood, such as human serum albumin (HSA). If this transfer is compromised, the drug might precipitate─a process that needs to be excluded under all circumstances. The key question of this paper is whether the high local concentration of GC at the moment and site of MDDS dissolution might transiently saturate HSA binding sites and, hence, endanger quick drug transfer. To address this question, we have used a new approach, which is time-resolved fluorescence spectroscopy of the single tryptophan in HSA, Trp-214, to characterize the competitive binding of GC and the drug substitute anilinonaphthalenesulfonate (ANS) to HSA. Time-resolved fluorescence of Trp-214 showed important advantages over established methods for tackling this problem. ANS has been the standard "model drug" to study albumin binding for decades, given its structural similarity to the class of naphthalene-containing acidic drugs and the fact that it is displaced from HSA by numerous drugs (which presumably bind to the same sites). Our complex global fit uses the critical approximation that the average lifetimes behave similarly to a single lifetime, but the resulting errors are found to be moderate and the results provide a convincing explanation of the, at first glance, counterintuitive behavior. Accordingly, and largely in line with the literature, we observed two types of sites binding ANS at HSA: 3 type A, rather peripheral, and 2 type B, likely more central sites. The latter quench Trp-214 by Förster Resonance Energy Transfer (FRET) with a rate constant of ≈0.4 ns-1 per ANS. Adding millimolar concentrations of GC displaces ANS from the A sites but not from B sites. At incomplete ANS saturation, this causes a GC-induced translocation of ANS from A to the more FRET-active B sites. This leads to the apparent paradox that the partial displacement of ANS from HSA increases its quenching effect on Trp-214. The most important conclusion is that (ANS-like) drugs cannot be displaced from the type-B sites, and consequently, drug transfer to these sites is not impaired by competitive binding of GC in the vicinity of a dissolving micelle. The second conclusion is that for unbound GC above the CMC (9 mM), ANS equilibrates between HSA and GC micelles but with a strong preference for free sites on HSA. That means that even persisting micelles would lose their cargo readily once exposed to HSA. For all MDDS sharing this property, targeted drug delivery approaches involving them as the nanocarrier would be pointless.

Critical Assessment of Micellar Surface Charge-Dependent Disaggregation and Reaggregation of a Bis-Indole Self-Aggregate: What Should Be Our Case-Dependent Choice?

"Aggregation-caused quenching" is a deep-seated mechanism and has been widely used by the researchers as the possible basis for new sensor development. Contrast to aggregation, its turn around process, disaggregation, has gained much less consideration so far. Unfortunately, study of the further scope for reaggregation of the disaggregated probe assembly in the same solution, as and when required, is still under the rare category. The central theme of the current study is focused on this aspect. For this purpose, the effects of headgroup charge (cationic, anionic, and nonionic) and polarity of the micelles on the degree of disaggregation and subsequent emission amelioration of a synthesized bis-indole derivative, 3,3'-bisindolyl(phenyl)methane (BIPM), are studied using steady-state and time-resolved spectroscopic techniques. The relative emission yield of BIPM (φf = 0.01) is significantly enhanced in the presence of cetyltrimethylammonium bromide (φf = 0.21) and polyoxyethylene (20) sorbitan monolaurate (φf = 0.24), whereas comparatively less emission enhancement is recorded within the sodium dodecyl sulfate system (φf = 0.07). In contrast, addition of an external biophilic agent, uric acid, causes requenching of the enhanced emission because of the reaggregation of the disaggregated probes. Detailed microscopic and calorimetric studies are also adopted to investigate the disaggregation-reaggregation mechanism of BIPM associations. The study will provide prior insights about the use of suitable micellar systems for the required degree of disaggregation as well as for the modulation of emission efficiency by controlled tuning of the disaggregation-reaggregation equilibrium for similar probe associations in pure aqueous medium avoiding any chemical transformation.

An unusual entrapment of ciprofloxacin by anionic-hydrophilic and cationic-hydrophilic mixed micellar system through complex formation

An unusual entrapment of ciprofloxacin by anionic-hydrophilic and cationic-hydrophilic mixed micellar system through complex formation

Micellar Matrices for Spectrophotometric Determination of 5-Aminosalicylic Acid in Medicinal Preparations Using Response Surface Methodology and Box-Benken Plans

Determination of the content of insoluble pharmaceutical substances in dosage forms is an urgent task, since their dosage is very important for the optimal ratio between the therapeutic effect and ensuring the necessary bioavailability. The use of micellar media as a matrix allows increasing solubility. This report presents the results of the influence of the micellar system consist from cetyltrimethylammonium bromide, CTAB, dimethyl sulfoxide, DMSO and water on the determination of the content of 5-aminosalicylic acid (5-ASA) in pharmaceutical substances and in dosage forms. 5-ASA is widely used for the treatment of inflammatory bowel diseases, ulcerative colitis and Crohn's disease. To obtain the optimal matrix, the methodology of the response surface (MRS) and three-level Box-Benken plans (BBP) were used. The intensity of the absorption band of 5-ASA (A330), which reflects the acid content, was used as the target function. The independent factors were: the concentration of CTAB (pC(CTAB), mol/l); the acidity of medium (pH); the proportion of DMSO in the binary solvent (αDMSO). The BBP consisting of fifteen compositions were compiled and response surfaces constructed. Optimal conditions for the determination of 5-ASA by the absorption band A330 are: pC(CTAB) = 1.1, pH = 7.6, α(DMSO) = 0.3. In this matrix, the content of 5-ASA in the pharmaceutical substance was established and good metrological performance was achieved. The use of MRS and BBP contributes to the development of effective methods for quality control of 5-ASA dosage forms from different manufacturers.

Concentration Dependent Asymmetric Synergy in SDS-DDAO Mixed Surfactant Micelles.

We investigate the structure and interactions of a model anionic/amphoteric mixed surfactant micellar system, namely, sodium dodecyl sulfate (SDS) and N,N-dimethyldodecylamine N-oxide (DDAO), employing SANS, FTIR, DLS, and pH measurements, in the range 0.1-100 mM total surfactant concentration and 0-100% DDAO. Increasing surfactant concentration is found to elongate the prolate ellipsoid micelles (RPolar ∼ 25-40 Å), accompanied by up to a 6-fold increase in micellar charge. The surfactant synergy, in terms of micellar charge and size, diffusion coefficient, solution pH, and headgroup interactions, was found to vary with concentration. At lower concentrations (≤50 mM), the SDS-DDAO ratio of maximum synergy is found to be asymmetric (at 65-85% DDAO), which is rationalized using regular solution theory, suggesting an equilibrium between Na+ dissociation, DDAO protonation, and counterion concentration. At higher concentrations, maximum synergy shifts toward the equimolar ratio. Overall, our study expands and unifies previous reports, providing a comprehensive understanding for this model, synergetic mixed micellar system.

Preparation of novel shell-ionotropically crosslinked micelles based on hexadecylamine and tripolyphosphate for cancer drug delivery

Aims Micellar systems have the advantage of being easily prepared, cheap, and readily loadable with bioactive molecular cargo. However, their fundamental pitfall is poor stability, particularly under dilution conditions. We propose to use simple quaternary ammonium surfactants, namely, hexadecylamine (HDA) and hexadecylpyridinium (HDAP), together with tripolyphosphate (TPP) anion, to generate ionotropically stabilized micelles capable of drug delivery into cancer cells. Methods optimized mixed HDA/HDAP micelles were prepared and stabilized with TPP. Curcumin was used as a loaded model drug. The prepared nanoparticles were characterized by dynamic light scattering, infrared spectroscopy, transmission electron microscopy, and differential scanning calorimetry. Moreover, their cellular uptake was assessed using flow cytometry and confocal fluorescence microscopy. Results The prepared nanoparticles were found to be stable under dilution and at high temperatures and to have a size range from 139 nm to 580 nm, depending on pH (4.6-7.4), dilution (up to 100 times), and temperature (25 – 80 °C). They were effective at delivering their load into cancer cells. Additionally, flow cytometry indicated the resulting stabilized micellar nanoparticles to be non-cytotoxic. Conclusions The described novel stabilized micelles are simple to prepare and viable for cancer delivery.

Recent insight into the advances and prospects of microbial lipases and their potential applications in industry.

Enzymes play a crucial role in various industrial sectors. These biocatalysts not only ensure sustainability and safety but also enhance process efficiency through their unique specificity. Lipases possess versatility as biocatalysts and find utilization in diverse bioconversion reactions. Presently, microbial lipases are gaining significant focus owing to the rapid progress in enzyme technology and their widespread implementation in multiple industrial procedures. This updated review presents new knowledge about various origins of microbial lipases, such as fungi, bacteria, and yeast. It highlights both the traditional and modern purification methods, including precipitation and chromatographic separation, the immunopurification technique, the reversed micellar system, the aqueous two-phase system (ATPS), and aqueous two-phase flotation (ATPF), moreover, delves into the diverse applications of microbial lipases across several industries, such as food, vitamin esters, textile, detergent, biodiesel, and bioremediation. Furthermore, the present research unveils the obstacles encountered in employing lipase, the patterns observed in lipase engineering, and the application of CRISPR/Cas genome editing technology for altering the genes responsible for lipase production. Additionally, the immobilization of microorganisms' lipases onto various carriers also contributes to enhancing the effectiveness and efficiencies of lipases in terms of their catalytic activities. This is achieved by boosting their resilience to heat and ionic conditions (such as inorganic solvents, high-level pH, and temperature). The process also facilitates the ease of recycling them and enables a more concentrated deposition of the enzyme onto the supporting material. Consequently, these characteristics have demonstrated their suitability for application as biocatalysts in diverse industries.

A highly sensitive micelle-sensitized spectrofluorimetric approach for analysis of montelukast in dosage forms and human plasma: Greenness assessment and application to content uniformity testing

In this work, a highly sensitive, rapid, affordable, and green micellar-enhanced spectrofluorimetric method was developed for the estimation of montelukast in its tablets and human plasma for the first time. After excitation at 224 nm, a micellar solution of cetrimide containing montelukast produced high native fluorescence emission at 404 nm. A 3-fold enhancement of the drug's fluorescence intensity and quantum yield, as well as the method's sensitivity, was produced using cetrimide as a micellar system. The experimental parameters influencing the spectrofluorimetric behavior of the studied drug were carefully investigated. The quantum yield of montelukast was also computed and found to be as high as 20 %. A straight-lined calibration plot was obtained over the concentration range of 50.0–1000.0 ng/mL. The proposed method showed high sensitivity down to the nanogram level with quantitation and detection limits of 34.68 and 11.45 ng/mL, respectively. The method was successfully applied for the analysis of the studied drug in its tablets with high % recoveries and low %RSD values. As the proposed fluorimetric method is highly sensitive and selective towards montelukast, it could successfully test the content uniformity of its tablets following the guidelines of the British Pharmacopoeia. Montelukast was also successfully determined in spiked human plasma samples due to the increased sensitivity of the method. The greenness profile and ecofriendliness of the proposed method were verified using two different green metrics, including AGREE and GAPI, which demonstrated the excellent greenness of the method. The developed method was validated according to ICH Q2 (R1) guidelines.

Controllable synthesis of porous N-doped carbons using aniline and Pluronic F127 micellar system for hydrogen storage and electrochemical applications

Controllable synthesis of porous N-doped carbons using aniline and Pluronic F127 micellar system for hydrogen storage and electrochemical applications

Specific FRET Probes Sensitive to Chitosan-Based Polymeric Micelles Formation, Drug-Loading, and Fine Structural Features.

Förster resonance energy transfer (FRET) probes are a promising tool for studying numerous biochemical processes. In this paper, we show the application of the FRET phenomenon to observe the micelle formation from surfactants, micelles self-assembling from chitosan grafted with fatty acid (oleic-OA, or lipoic-LA), cross-linking of SH groups in the micelle's core, and inclusion and release of the model drug cargo from the micelles. Using the carbodiimide approach, amphiphilic chitosan-based polymers with (1) SH groups, (2) crosslinked with S-S between polymer chains, and (3) without SH and S-S groups were synthesized, followed by characterization by FTIR and NMR spectroscopy. Two pairs of fluorophores were investigated: 4-methylumbelliferon-trimethylammoniocinnamate-rhodamine (MUTMAC-R6G) and fluorescein isothiocyanate-rhodamine (FITC-R6G). While FITC-R6G has been described before as an FRET-producing pair, for MUTMAC-R6G, this has not been described. R6G, in addition to being an acceptor fluorophore, also serves as a model cytostatic drug in drug-release experiments. As one could expect, in aqueous solution, FRET effect was poor, but when exposed to the micelles, both MUTMAC-R6G and FITC-R6G yielded a pronounced FRET effect. Most likely, the formation of micelles is accompanied by the forced convergence of fluorophores in the hydrophobic micelle core by a donor-to-acceptor distance (r) significantly closer than in the aqueous buffer solution, which was reflected in the increase in the FRET efficiency (E). Therefore, r(E) could be used as analytical signal of the micelle formation, including critical micelle concentration (CMC) and critical pre-micelle concentration (CPMC), yielding values in good agreement with the literature for similar systems. We found that the r-function provides analytically valuable information about the nature and mechanism of micelle formation. S-S crosslinking between polymer chains makes the micelle more compact and stable in the normal physiological conditions, but loosens in the glutathione-rich tumor microenvironment, which is considered as an efficient approach in targeted drug delivery. Indeed, we found that R6G, as a model cytostatic agent, is released from micelles with initial rate of 5%/h in a normal tissue microenvironment, but in a tumor microenvironment model (10 mM glutathione), the release of R6G from S-S stitched polymeric micelles increased up to 24%/h. Drug-loading capacity differed substantially: from 75-80% for nonstitched polymeric micelles to ~90% for S-S stitched micelles. Therefore, appropriate FRET probes can provide comprehensive information about the micellar system, thus helping to fine-tune the drug delivery system.

Physicochemical Properties of Cetrimonium Bromide in Electrolytes and Nonelectrolyte Environments

Background: The physicochemical properties, including the thermodynamics of micellization studies, received much attention. Cationic surfactant cetrimonium bromide (C16TABr) in electrolytes (sodium chloride and sodium salicylate) and nonelectrolyte (Ethylene glycol) in an aqueous solution were examined, and interesting results were obtained. The present investigation aims to identify a suitable combination of cationic surfactant cetrimonium bromide + electrolytes and nonelectrolytes having the ability to alter the size or shape of the micellar system using available methods. Methods: Surface tension, conductivity, viscosity, ultrasonic velocity, and dynamic light scattering (DLS) methods at different temperatures (303-323K) were used during the experimental research work. Results: The experimental results pointed out that the incorporation of electrolytes and nonelectrolyte into the cationic surfactant affects the physicochemical properties such as critical micelle concentration (CMC), surface tension (ST), degree of ionization (α), degree of counterion binding (β), standard Gibbs free energy of micellization (ΔGo m), standard entropy of micellization (ΔSo m), standard heat of micellization (ΔHo m), viscosities, and acoustic parameters. Dynamic light scattering (DLS) measurements reveal exciting facts related to the size and shape transformation of the mixed micellar assembly. Structure modification can be obtained by choosing right the combination of cationic surfactant cetrimonium bromide + electrolytes (sodium chloride and sodium salicylate) and nonelectrolyte (Ethylene glycol) ratio. Conclusion: It concluded that, over a threshold level, an electrolyte such as NaCl concentration causes the micelle size to rise. The entropy of micellization goes down when a structure-breaker (EG) is added to the water phase, and this is because the structure of the water is changed near hydrophobic groups. The physicochemical features of cetrimonium bromide (C16TABr) show unique behaviour under the influence of micelle-driven and micelle- forbidden systems.

Enhancing solubilization of Nebivolol hydrochloride through tuning pluronic F-127 with ionic Surfactants: An experimental and theoretical investigation

In the present work, the interaction of the antihypertensive drug Nebivolol hydrochloride (NBL) with nonionic surfactant pluronic F-127 (F-127) is investigated in an aqueous medium. Two ionic surfactants, viz., cationic, cetyl trimethyl ammonium bromide (CTAB) and anionic, sodium tetradecyl sulphate (STS) were added to F-127 to improve the physicochemical properties of the single micellar medium. The characterization techniques employed were, FTIR, UV–visible spectroscopy, dynamic light scattering, zeta potential, antioxidant, conductivity, and FESEM studies. The critical micellar concentration (CMC) of CTAB and STS are estimated from the conductivity experiments which is lowered due to the addition of F-127 and NBL. The lowering of CMC is attributed to the solubilization of NBL in the binary micellar mediums. The extent of binding of NBL in F-127, F-127 + CTAB, and F-127 + STS were quantified by determining the binding constant values using the Benesi–Hildebrand (B-H) plot from UV absorbance data. They were, 838.2 M−1 for F-127 1100.7 M−1 for F-127 + CTAB and 1836.5 M−1 for F-127 + STS systems. There was an increase in the size of the micelle due to the encapsulation of the drug in both binary micellar systems. The zeta potential (ZP) values displayed enhanced stability of the drug in binary micellar systems. The radical scavenging activity (RSA %) of NBL was estimated to be 16.5 % in F-127, 24.7 % in F-127 + CTAB, and 44.9 % in F-127 + STS systems. The encapsulation efficiency (EE %) for the above three systems were 14.7 %, 16.4 % and 18.5 %, respectively. The surface parameters and the interactions were verified through molecular docking studies. The results suggest that the properties of F-127 can be improved by tuning with ionic surfactants to solubilize NBL. To our knowledge, this is the first report of NBL solubilization in mixed micellar systems. Similar studies with other drug systems can be applied to get improved results.

The GARD Prebiotic Reproduction Model Described in Order and Complexity.

Early steps in the origin of life were necessarily connected to the unlikely formation of self-reproducing structures from chaotic chemistry. Simulations of chemical kinetics based on the graded autocatalysis replication domain (GARD) model demonstrate the ability of a micellar system to become self-reproducing units away from equilibrium. Even though they may be very rare in the initial state of the system, the property of their endogenous mutually catalytic networks being dynamic attractors greatly enhanced reproduction propensity, revealing their potential for selection and Darwinian evolution processes. In parallel, order and complexity have been shown to be crucial parameters in successful evolution. Here, we probe these parameters in the dynamics of GARD-governed entities in an attempt to identify characteristic mechanisms of their development in non-covalent molecular assemblies. Using a virtual random walk perspective, a value for consecutive order is defined based on statistical thermodynamics. The complexity, on the other hand, is determined by the size of a minimal algorithm fully describing the statistical properties of the random walk. By referring to a previously published diagonal line in an order/complexity diagram that represents the progression of evolution, it is shown that the GARD model has the potential to advance in this direction. These results can serve as a solid foundation for identifying general criteria for future analyses of evolving systems.

Design of polymeric carriers to enhance antimicrobial photodynamic inactivation

Mixed polymeric micelles are a promising tool for the design of nanocarriers with pharmaceutical properties. These micellar systems allow reversing numerous properties of lipophilic drugs. Particularly, when applied to transport photosensitizers (PSs), they give rise to a wide variety of nanophotosensitizers (nPSs). These compounds are used to inactivate numerous bacteria resistant to conventional antibiotics. This research proposes the development of new mixed micelles, with better properties than simple micelles, for the trapping of Neutral Red (NR) and its monobrominated derivative (NRBr). Based on the combination of Pluronic P-123 with Pluronic F-108, Pluronic L-61 and Tween 80, 15 binary micellar systems were obtained. These mixed micelles presented a single population of homogeneous particles, with a diameter less than 70 nm. Moreover, several mixed micelles show smaller CMC than the simple system. These properties are predictors of high micellar stability and good anti-dilution properties, favoring their drug delivery applications. For these reasons, were loaded with NR and NRBr, showing good encapsulation efficiency. The 30 new nPSs presented an adequate size for pharmaceutical use and markedly enhanced the photochemical reactivity of the free PSs. Many of the mixed micellar systems showed greater production of singlet oxygen than the simple micelles of Pluronic P-123. Furthermore, all micellar systems increased the chemical stability of NRBr, which degrades in pH 7.4 buffer solution. Finally, all nPSs presented greater phototoxic activity against methicillin-resistant Staphylococcus aureus than free PSs. The nPSs formed by P-123: F-108 (90:10) + NR, P-123: F-108 (90:10) + NRBr, P-123: L-61 (80:20) + NRBr and P −123: T80 (80:20) + NRBr caused greater photodynamic inactivation of the microorganism than simple P-123 micellar systems. These nPSs could be considered excellent candidates for application in the treatment of infections caused by bacteria resistant to antibiotics.

Physicochemical investigation of encapsulation of antihypertensive drug captopril in mixed micellar system to enhance its delivery

This research work provides insight into the solubilization of a non-ionic drug captopril (CAP) in the micellar media of cationic surfactant cetyltrimethylammonium bromide (CTAB) and mixed micellar media of two nonionic surfactants Tween-80 and Triton X-100. CAP−surfactant interactions were analyzed by simple and differential absorption spectroscopy as well as by conductometry and the efficiency of the selected micellar system was assessed by calculating the values of partition coefficient (Kx), the free energy of partition (∆GP), binding constant (Kb) and the free energy of binding (∆Gb). Results from differential spectroscopy depicted a noteworthy increase in the solubilization of CAP with the addition of nonionic surfactants (Tween-80 and TX-100) in the micellar solution of CTAB. Furthermore, conductometric response of micellar media has been used to calculate the degree of dissociation (β), the free energy of micellization (∆Gm) thermodynamic parameters of micellization.

Chondroitin Sulfate-Derived Micelles for Adipose Tissue-Targeted Delivery of Celastrol and Phenformin to Enhance Obesity Treatment.

Adipose tissue macrophages (ATMs) are crucial in maintaining a low-grade inflammatory microenvironment in adipose tissues (ATs). Modulating ATM polarization to attenuate inflammation represents a potential strategy for treating obesity with insulin resistance. This study develops a combination therapy of celastrol (CLT) and phenformin (PHE) using chondroitin sulfate-derived micelles. Specifically, CLT-loaded 4-aminophenylboronic acid pinacol ester-modified chondroitin sulfate micelle (CS-PBE/CLT) and chondroitin sulfate-phenformin conjugate micelles (CS-PHE) were synthesized, which were shown to actively target ATs through CD44-mediated pathways. Furthermore, the dual micellar systems significantly reduced inflammation and lipid accumulation via protein quantification and Oil Red O staining. In preliminary in vivo studies, we performed H&E staining, immunohistochemical staining, insulin tolerance test, and glucose tolerance test, and the results showed that the combination therapy using CS-PBE/CLT and CS-PHE micelles significantly reduced the average body weight, white adipose tissue mass, and liver mass of high-fat diet-fed mice while improving their systemic glucose homeostasis. Overall, this combination therapy presents a promising alternative to current treatment options for diet-induced obesity.

Enhancing Oral Delivery and Anticancer Efficacy of 7-Ethyl-10-Hydroxycamptothecin through Self-assembled Micelles of Deoxycholic Acid Grafted N'-nonyl-trimethyl Chitosan

Irinotecan (CPT-11) is used as a first or second-line chemotherapy drug for the treatment and management of colorectal cancers. In vitro studies have shown that 7-ethyl-10-hydroxycamptothecin (SN38), the active metabolite of CPT-11, displays promising anticancer efficacy. However, its poor aqueous solubility and hydrolytic degradation result in its lower oral bioavailability and impracticable clinical application. To overcome these limitations, a novel amphiphilic chitosan derivative, deoxycholic acid decorated N’-nonyl-trimethyl chitosan, was synthesized. Nano-micelles loaded with SN38 were subsequently prepared to enhance the bioavailability and anti-tumor efficacy of the drug through oral administration. The nano-micelles demonstrated improved dilution stability, enhanced greater mucosal adherence, significant P-gp efflux inhibition, and increased drug transport in the intestine by paracellular and transcellular pathways. Consequently, both the in vivo pharmacokinetic profile and therapeutic efficacy of SN38 against cancer were substantially improved via the micellar system. Thus, the developed polymeric micelles can potentially enhance the SN38 oral absorption for cancer therapy, offering prospective avenues for further exploration.

Effect of polysaccharide-protein interactions on the multi-scale structure of hybrid micellar casein-xanthan gum systems

This study reports on the effect of pH and polysaccharide concentration (protein:polysaccharide ratios of 95:5, 85:15 and 75:25) on the interactions established between xanthan gum (XG) and micellar casein (MC), investigating the impact on the type of structures formed at the micro- and nanoscale. At pH ≥ 6, the micellar casein formed stable suspensions where micelles with diameters of ca. 130–150 nm showed a compact inner structure stabilised by colloidal calcium phosphate (CCP) nanoclusters, while at pH ≤ 3, a more loosely packed interconnected network structure, stabilised by protein-protein interactions, was noted. The addition of XG, even at low MC:XG ratios (95:5), resulted in increased stability of the system, preventing the formation of micelle aggregates at the microscale, and reducing the pH range at which casein precipitated close to the isoelectric point. For all the XG loadings, coacervates were formed at pH = 2–3 due to polysaccharide-protein electrostatic interactions, leading to separation into a solid gel-like phase composed of polysaccharide-protein fibrillar structures and a liquid phase rich in protein. At the nanoscale, XG was mostly coating the micelles and filling in the inner water channels when added at MC:XG ratios ≤85:15, while the higher polysaccharide content at the ratio 75:25 allowed to form an interconnected structure. Therefore, by adjusting pH and XG concentration, it is possible to improve casein stability, reduce agglomeration and manipulate the size of protein-polysaccharide complexes formed. This will be of great relevance for the development of novel food formulations with improved stability and modulated sensory and nutritional properties.

Scrutinizing micellar transitions and interfacial properties in mixed micelles comprising sodium dodecyl sulfate and sodium oleate: A tensiometric and scattering insight

Mixed micellar systems play a pivotal role in numerous scientific and industrial applications due to their inimitable solution properties and potential for enhancing solubilization and emulsification processes. The present study unveils the mixed micellization behavior of two anionically charged surfactants, sodium dodecyl sulfate (SDS) and sodium oleate (SO), in aqueous solutions through a combination of solution viscosity, tensiometric and small-angle neutron scattering (SANS) techniques. The dynamic changes in the interfacial properties of the mixed micellar system as a function of the SDS-to-SO ratio are evaluated from surface tension measurements. The results offer an insight into the formation of the stable mixed micelles with the alteration in the critical micelle concentration (CMC) as a function of the composition of both surfactants and the nature of the interaction. Surface tension data disclose the thermodynamic aspects of micelle formation and the influence of surfactant interactions on the surface activity of the system. Complementing the surface tension measurements, SANS analysis was conducted to clarify the structural aspects of the SDS-SO mixed micelles. SANS inferred the micellar size, shape, and aggregation number (Nagg), thereby shedding light on the nanoscale organization of the micellar aggregates in the aqueous solution. By combining SANS and surface tension data, a comprehensive understanding of the mixed micellization behavior of SDS and SO is achieved, addressing both interfacial and structural aspects. A computational simulation approach has also been employed to obtain the optimized parameters, which provide a better understanding of the correlation of SDS and SO molecular orbital energy levels. The results underscore the importance of surface tension and structural characterization techniques to comprehend the behavior of mixed micelles fully.