Particle Size Of Micelles Research Articles

Preparation and response behaviour of wormlike micelles in response to CO2 stimulation

Low-permeability reservoirs have a lot of reserves, but there is the phenomenon that gas injection is prone to gas flushing during the development process. CO2 foam drive combines the dual advantages of CO2 drive and foam drive, which can significantly lessen CO2 gas flushing and expand the wave efficiency of the replacement phase. The conventional CO2 foam system contains a large number of foaming agents and foam stabilizers. Still, there are issues such as high viscosity of the extracted fluid, serious emulsification, and difficulty in foam defoaming, which leads to the difficulty and high cost of treating the extracted fluid. In this study, the best performing wormlike micelles system of 0.6 wt% DOAPA@NaSal-H+ to stabilise the CO2 foam system was prepared by preferring N, N-dimethyl-3-oleamidopropylamine (DOAPA) and sodium salicylate (NaSal), using foam performance as an indicator. Analytical tests include conductivity test, rheological property test, surface tension test, Cryo-SEM, DLS are employed. According to the findings, the system under the influence of CO2 exhibits an increase in the chemical shift of hydrogen atoms near the N atom, an increase in the conductivity of the system, a lamellar mesh microstructure, and an average particle size of micelles of 104.6 nm. The surface tension of DOAPA@NaSal-H+ decreases with the increase of concentration, and the apparent viscosity decreases with the increase of shear rate, which exhibits the typical viscoelastic fluid behaviour. It is important to study the stimulus-response rows of CO2 stimulus responsive wormlike micelles, which provides theoretical support for the stabilization of CO2 foams by wormlike micelles.

Dual-targeted transferrin and AS1411 aptamer conjugated micelles for improved therapeutic efficacy and imaging of brain cancer

Brain tumors represent an aggressive form of cancer, posing significant challenges in achieving complete remission. Development of advanced therapies is crucial for improving clinical outcomes in cancer patients. This study aimed to create a novel treatment approach using dual-targeted transferrin (TF) and AS1411 conjugated micelles, designed to enhance therapeutic effectiveness of docetaxel (DTX) and facilitate gadolinium (Gd) based imaging in brain cancer. Micelles were prepared using a slightly modified solvent-casting method, and the dual-targeting ligands were attached to the micelle’s surface through a physical adsorption process. Average particle size of micelles ranged from 117.49 ± 3.90–170.38 ± 3.39 nm, with a low polydispersity index. Zeta potential ranged from − 1.5 ± 0.02 to − 18.7 ± 0.04 mV. Encapsulation efficiency of DTX in micelles varied from 92.64 ± 4.22–79.77 ± 4.13 %. Simultaneously, encapsulation of Gd in micelles was found to be 48.27 ± 3.18–58.52 ± 3.17, respectively. In-vitro drug release studies showed a biphasic sustained release profile, with DTX and Gd release continuing up to 72 h with their t50 % at 4.95, 11.29, and 24.14 h for GDTP, GDTP-TF and GDTP-TF-AS1411 micelles, respectively. Cytotoxicity effect of GDTP-TF-AS1411 micelles has shown significant improvement (P < 0.001) and reduced IC50 value up to 0.19 ± 0.14 μg/ml compared to Taxotere® (2.73 ± 0.73 μg/ml). Theranostic study revealed higher accumulation of GDTP-TF and GDTP-TF-AS1411 micelles free GD treated animal brains. The AUC of GDTP-TF-AS1411 micelles exhibited 23.79 ± 17.82 μg.h/ml higher than Taxotere® (14.14 ± 10.59 μg.h/ml). These findings direct enhanced effectiveness in brain cancer therapy leading to improved therapeutics in brain cancer patients. The combined targeted ligands and therapeutic agents strategy can direct advancement in brain cancer therapy and offer improved therapy for patients.

Naphthyl-Poly(S-((2-carboxyethyl)thio)-l-cysteine) Peptide Amphiphiles with Different Degrees of Polymerization: Synthesis, Self-Assembly, pH/Reduction-Triggered Drug Release, and Cytotoxicity.

Four peptide amphiphiles (PA1-4) with different degrees of polymerization (DP = 40, 15, 10, and 6) were synthesized by Fuchs-Farthing and ring-opening polymerization followed by post-polymerization modification, as fully characterized by 1H NMR, FT-IR, gel permeation chromatography, and circular dichroism (CD) spectroscopy. It was found that PAs could self-assemble to form regular spherical micelles in low-concentration (about 1 mg/mL) aqueous solution, which had different contents of secondary structures and mainly adopted random coil conformations. The water solubility of PAs increases with the increase of DP, the polypeptide chain stretches randomly in water, the β-sheets decrease, and the random coil conformations dominate. When the pH of PA solution decreases or increases, intramolecular hydrogen bonds break, and molecular chains stretch, leading to a decrease of α-helix, turn conformations, and an increase of β-sheets. Meanwhile, the particle size of micelles increases. At around 0.4 mg/mL, the hemolysis ability of PA2 is negligible at pH 7.4 and 6.5 and about 33% at pH 5.5. Cisplatin (CDDP) was linked to micelles by coordination bonds to explore their potential as drug carriers, exhibiting controlled pH and reduction in dual drug release effects. MTT assay showed that the HeLa cell viability was 78% when cultured in the 13.5 μg/mL PA2 blank micelles for 2 days, while the cell viability was 60% in the CDDP-loaded micelles. Furthermore, a high concentration of PA2 (about 100 mg/mL) could self-assemble into a fibrous hydrogel at pH 5.5, which self-healed 2 h after incision and self-degraded 71% within 14 days. The CDDP-loaded fiber hydrogel exhibited a sustained release effect similar to the CDDP-loaded micelles. The cytotoxicity of CDDP-loaded fibers at 48 h was detected to be the same as that of the same amount of CDDP, and the cell viability was 7%. Therefore, we provide a new strategy for the synthesis of amphiphilic peptides with potential applications in nano-drug carriers and cancer therapy.

Developing an optical backscatter method for determining casein micelle particle size in heated milk

A plethora of different factors, such as heat treatment, pH, soluble calcium and phosphate concentrations, colloidal calcium phosphate, ionic strength, redox potential, etc., affect functionally of critical milk components such as casein micelles, fat globules and whey proteins. These physicochemical changes induce fat- or protein-protein interactions that would be associated to changes in particle size that might be revealed using light backscatter measurements. We hypothesized that inline, simple, low-cost light backscatter measurements might have the potential to provide functionally related information, representing an interesting opportunity for process control. Casein micelle particle size and near infrared light backscatter spectra were measured in milks heat treated at 80 and 90 °C and pH 6.3, 6.7 and 7.1 in order to obtain prediction models for estimating changes in casein micelle particle size during milk heat treatment. Light intensity was measured over a spectral range of 200–1100 nm using a simple optical backscatter sensor and was implemented into models for particle size predictions as a function of heat treatment temperature and pH. Models which included an exponential factor containing a ratio of two specific wavebands were found to improve R2 when compared to single wavelength models. The best model exhibited an R2 of 0.993 and SEP of 2.36 nm. The developed prediction models show promise for in-line monitoring of whey protein denaturation and casein micelle particle size.

Coarse-Grained Molecular Dynamics Simulations of Paclitaxel-Loaded Polymeric Micelles.

A continuous manufacturing technology based on coaxial turbulent jet in coflow was previously developed to produce paclitaxel-loaded polymeric micelles. Herein, coarse-grained molecular dynamics (CG-MD) simulations were implemented to better understand the effect of the material attributes (i.e., the drug-polymer ratio and the ethanol concentration) and process parameters (i.e., temperature) on the self-assembly process of polymeric micelles as well as to provide molecular details on micelle instability. An all-atom (AA) poly (ethylene glycol)-poly (lactic acid) (PEG-PLA) polymer model was developed as the reference for parameterizing a coarse-grained (CG) model, and the AA polymer model was further validated with experimental glass transition temperature (Tg). The model transferability was verified by comparing structural properties between the AA and CG models. The CG model was further validated with experimental data, including micelle particle size measurements and drug encapsulation efficiency. Furthermore, the encapsulation of paclitaxel into the polymeric micelles was included in the simulations, taking into consideration the interactions between the paclitaxel and the polymers. The results from various points of view demonstrated a strong dependence of the shape of the micelles on the drug encapsulation, with micelles transitioning from spherical to ellipsoidal structures with an increasing paclitaxel amount. Simulation data were also used to identify the critical aggregation number (i.e., the number of polymer and drug molecules required for transition from one shape to another). Improved micellar structural stability was found with a larger micellar size and less solvent accessibility. Lastly, an evaluation was performed on the micellar dissociation free energy using a steered molecular dynamics simulation over a range of temperatures and ethanol concentrations. These simulations revealed that at higher ethanol and temperature conditions, micelles become destabilized, resulting in greater paclitaxel release. The increased drug release was determined to originate from the solvation of the hydrophobic core, which promoted micellar swelling and an associated reduction in hydrophobic interactions, leading to a loosely packed micellar structure.

Formulation and performance evaluation of polymeric mixed micelles encapsulated with baicalein for breast cancer treatment

The present study is aimed to formulate baicalein-loaded mixed micelles to enhance the solubility and oral bioavailability. Baicalein encapsulated D-α-tocopherol polyethylene glycol 1000 succinate (TPGS) and pluronic F127 (F127) combined micelles were prepared and investigated for anticancer effect. The optimized formulation contains 25.04 ± 0.24 nm mean particle size of micelles with a zeta potential value of −4.01 ± 0.5 mV. The calculated entrapment efficiency percentage of baicalein within the micellar structure was 83.43 ± 0.13% and the in vitro release of baicalein from micelles displayed a sustained release profile at pH 7.4. The incorporation of baicalein within micelles core was also confirmed by FTIR analysis of formulation, which hardly represents the characteristic peak of baicalein, indicating successful entrapment of the drug. In vitro cell culture experiments revealed baicalein-loaded micelles significantly enhanced cellular uptake and cytotoxicity against MDAMB-231 cell lines in comparison to free baicalein. Additionally, as compared to free baicalein, baicalein micelles demonstrated greater apoptosis-inducing potential while the results of the cell cycle study exhibited arrest of cells at the G0/G1 phase of the cell cycle. Results of ROS (reactive oxygen species) and MMP (mitochondrial membrane potential) assay revealed the ROS-dependent mitochondrial-mediated apoptosis pathway utilized by developed formulation to inhibit cell proliferation. Thus, the developed nano micelles can serve as a potent carrier system for baicalein against breast cancer.

De novo synthesis of pH-responsive, self-assembled, and targeted polypeptide nano-micelles for enhanced delivery of doxorubicin

Doxorubicin (DOX) is a commonly used anticancer drug, but it is inefficient as a therapeutic due to a lack of targeting. Peptide-tuned self-assembly of DOX offers a strategy to improve targeting for greater efficacy. In this work, we designed and prepared an amphiphilic tumor cell-targeting peptide, P14 (AAAAFFFHHHGRGD), able to encapsulate DOX by self-assembly to form tumor cell-targeting and pH-sensitive nano-micelles. The results showed a critical P14-micelle concentration of 1.758 mg l−1 and an average particle size of micelles of 121.64 nm, with entrapment and drug-loading efficiencies of 28.02% ± 1.35% and 12.06% ± 0.59%, respectively. The prepared micelles can release 73.52 ± 1.27% DOX within 24 h in pH 4.5 medium, and the drug cumulative release profile of micelles can be described by the first-order model. Compared with free DOX, the micelles exhibited an increased ability to inhibit tumor cell growth and cause tumor apoptosis in vitro, with IC50 values of DOX and P14-DOX micelles against human breast cancer cells (MCF-7) of 0.91 ± 0.07 and 0.75 ± 0.06 μg ml−1, respectively, and cellular apoptotic rates of DOX and P14-DOX micelles of 70.3% and 42.4%, respectively. Cellular uptake experiments revealed high concentrations of micelles around and inside MCF-7 cells, demonstrating that micelles can target tumor cells. These results indicate the excellent potential for the application of this amphiphilic peptide as a carrier for small-molecule drugs and suggest a strategy for the design of effective anti-tumor drugs.

Aggregation behavior of a pH-responsive cationic–nonionic silicone surfactant in aqueous solution

A novel pH-sensitive cationic–nonionic silicone surfactant with a tertiary nitrogen head group and poly(ethylene oxide) hydrophilic chain was synthesized and characterized by 1H NMR and FT-IR spectroscopies. The surface activity and micellization behavior under acidic, neutral, and basic conditions were characterized by static surface tension (SST), dynamic surface tension (DST), fluorescence, particle size, and zeta potential techniques. The results showed that the cationic–nonionic silicone surfactant exhibited excellent surface activity, which depended on the aqueous solution pH. Both the critical micelle concentration (CMC) and micelle particle size were significantly different at different pH values. The SST results revealed a change in the CMC of the surfactant from 1.88 g·L−1 at pH 4 to 0.32 g·L−1 at pH 10. Moreover, the mesoequilibrium time, determined by DST, significantly decreased with increasing pH, demonstrating that the interface effectiveness was higher at high pH. The micelle morphology changed from 10 to >100 nm when the pH was varied from 3 to 10. Owing to these properties, the proposed surfactant shows great potential for application in many pH-response-related fields such as coatings, drug carriers, and pesticides.

The research on multi‐responsive azobenzene block copolymer and its self‐assembly behavior

AbstractThe azobenzene‐based amphiphilic copolymers have drawn significant attention as a kind of multi‐responsive smart materials. The demand on deeper investigation of how the azobenzene group influences the micelles formation and light‐responsive behavior on molecular level is very urgent. In this article, multi‐responsive block copolymers, poly (acrylic acid)‐block‐poly[4'‐[[(2‐Methacryloyloxy)ethyl]ethylainino]azobenzene‐co‐poly (ethylene glycol) methyl ether methacrylate] (PAA‐b‐P (AzoMA‐co‐PEGMA)), with pH‐, light‐ and reduction‐responsiveness were synthesized by the monomers of AzoMA, PEGMA and acrylic acid via reversible addition‐fragmentation chain transfer polymerization (RAFT). The amphiphilic block copolymer presented aggregation‐induced emission effect, and it was pH, light, and reduction responsive. The results showed that the micelle size decreased with the decreasing of pH within a certain range. However, the particle size of micelles increased significantly when the pH was 4. Once adding reduction agent, the micelles were disassembly. Fluorescent molecule of Nile red was selected as a hydrophobic guest molecule to study the properties of encapsulating and releasing abilities of block copolymer micelles for guest molecules. The results showed that the loading capacity of three kinds of copolymer micelles was closely related to the aggregates formed by the hydrophobic block, mainly azobenzene block. Besides, the block copolymer micelles could release a certain amount of Nile red under the irradiation of UV light, the reduction with Na2S2O4 as reductant, and the exposure to alkaline environment. The mechanism of how the different status of azobenzene group influenced the self‐assembly and multi‐responsive behavior was explored on molecular level.

Mechanism of the dissolution of methane in the complex micellar system of NaOA/cyclohexane

The surfactant sodium oleate (NaOA) has important applications in dissolving methane, but there is insufficient research regarding the dissolution mechanism of methane in compound solutions of NaOA. Cyclohexane can also be used as a reagent to dissolve methane because of the similar phase dissolution principles. Thus, surfactant NaOA and the compounding reagent cyclohexane are selected as the experimental subjects of this study. In this study, the optimum ratio of NaOA to cyclohexane and the dissolution mechanism of methane in the mixed solution are microscopically determined by measuring the amount of methane dissolution, critical micelle concentration, particle size, and micelle morphology in the mixed solutions. Compared with the single NaOA solution, the mixed solutions of NaOA and cyclohexane have lower critical concentrations of micelles, more concentrated micelle particle size distributions, and more extended and aggregated micelle morphologies, all of which lead to higher methane solubilities in the mixed solutions. The optimum NaOA to cyclohexane ratio for dissolving methane is 1:3. The NaOA to cyclohexane concentration ratio of 1:3 demonstrates the lowest critical micelle concentration, which is most likely to generate micelles with a hydrophobic environment favorable for the dissolution of methane. The mixed solution at this ratio also demonstrates the most suitable particle size distribution and micelle morphology for the retention of methane in the core of the micelle.

Mechanism for the complex micellar system of sodium dodecyl sulfate/octylphenol ethoxylate OPE9 to solubilize methane

Surfactant solutions are widely used in solubilizing methane, but there is a lack of research on the optimum ratios of surfactant solutions and their mechanism. In this study, surfactants sodium dodecyl sulfate (SDS) and octylphenol ethoxylate OPE9 (Triton X-100) were selected to better understand the mechanism of the surfactant solution to solubilize methane from a microscopic aspect. The mixed SDS and Triton X-100 solution was proven greater at methane solubilization than a single-component SDS, because it generated a higher number of micelles with hydrophobic cores. When the SDS–to–Triton X-100 concentration ratio was 1:4, the lowest critical micelle concentration, the strongest interaction between SDS and Triton X-100, the maximum absolute value of Gibbs free energy, and the maximum value of viscosity were observed. This indicated that the solution was most likely to generate micelles with a hydrophobic environment and that these micelles were favorable for the methane solubilization. This solution also showed a greater uniformity of micelles, a smaller micelle particle size, and a relatively compact micelle structure. It was deduced that methane stays longer in the micelle core of this structure, which can facilitate methane solubilization. The optimum SDS–to–Triton X-100 ratio to solubilize methane was shown to be 1:4.

Multi-Functional Drug Carrier Micelles With Anti-inflammatory Drug.

The multi-functional micelles poly(N-isopropylacrylamide-co-N,N-dimethylacrylamide-co-10 undecanoic acid)/CM-Dextran Fe3O4 (PNDU/CM-Dex Fe3O4) were poly (NIPAAm-co-DMAAm-co-UA) (PNDU) grafting hydrophilic CM-Dextran Fe3O4 which possess pH-dependent temperature response and magnetic response. In this research, anti-inflammation drug Hesperetin was encapsulated by micelles using membrane dialysis method to obtain the different ratio of Hesperetin-embedded P5DF10, P10DF10, and P20DF10. These micelles were characterized by Fourier transform infrared spectroscopy, 1H-NMR, thermogravimetric analyzer, and superconducting quantum interference device magnetometer. The morphology and particle size of micelles was observed by transmission electron microscopy and dynamic light scattering. The low critical solution temperature of the P10DF10 micelles is in pH 6.6 at about 37.76°C and in pH 7.4 at about 41.70°C. The biocompatibility of micelles was confirmed by cytotoxicity study. Inflammatory inhibition of hesperetin-embedded P10DF10 micelles also studied through RAW264.7. Hesperetin-embed P10DF10 micelles suppressed LPS-induced inflammatory response. Via immunofluorescence cell staining demonstrate that Hesperetin-embed P10DF10 micelles inhibited the activation of NF-κB p60 and markedly attenuated in a drug dose-dependent manner. At a concentration of 1,000 ug/ml, an inflammatory rate can be reduced to 36.9%. Based on these results, the hesperetin-embed P10DF10 micelles had successfully synthesized and enable to carry and release the anti-inflammatory drugs, which instrumental for biomedical therapy and applications.

Effects of isomaltodextrin in postprandial lipid kinetics: Rat study and human randomized crossover study.

Isomaltodextrin (IMD) is a novel dietary fiber-like polysaccharide: a type of α-glucan produced from starch using enzymes derived from microorganisms. The results of cohort studies show that dietary fiber can prevent cardiovascular disorders caused by lifestyle-related diseases such as metabolic syndrome. Inhibition of excess fat absorption by dietary fiber is known to be one of the mechanisms, and it is also known that the actions of dietary fiber vary depending on factors such as its structure or origin. Thus, we investigated the inhibitory actions of IMD on fat absorption, and analyzed its mechanism of action. In rats, the absorption of fat given by gavage was significantly lower at 1, 2, and 6 hours after IMD administration than after vehicle administration. In humans, IMD was associated with a lesser increase in blood triglycerides in subjects whose blood triglycerides were otherwise apt to rise. We also found by in vitro emulsion studies that IMD, which had no effect on digestive enzyme activity or emulsion formation, stabilized the micro size micelle by inducing enlarged micelle particle size and increased zeta potential. In conclusion, the mechanism of inhibition of fat absorption by IMD may be a delay in micelle particles accessing the intestinal epithelium through changes in the surface structure and the physical properties of the micelle particles.

Analysis of the preferential mechanisms of denaturation of whey protein variants as a function of temperature and pH for the development of an optical sensor

A pH‐ and temperature‐dependent study was conducted using reconstituted low‐heat skim milk at pH 6.3, 6.7 and 7.1 heated for 10 min at 80 and 90 °C to evaluate the relationship between bound and aggregate whey protein and optical light backscatter response. Significant correlations were found between casein micelle particle size and bound whey protein, and light backscatter correlations existed with both bound and aggregate whey protein, thus optical light backscatter may be useful to determine both whey protein attachment to the casein micelle and the formation of whey protein aggregates.

Synthesis, characterization and anti-cancer activity of Pluronic F68–curcumin conjugate micelles

Curcumin (CUR), a nontoxic polyphenol derived from the rhizome of turmeric (Curcuma longa), has been recognized as an anti-cancer and chemo-preventative agent. However, its clinical application for cancer treatment has been greatly limited due to its poor water-solubility and low bioavailability. To tackle this problem, Pluronic F68–CUR (F68–CUR) conjugate micelles, which are amphiphilic copolymers, were designed and synthesized in this study. These highly stable micelles with CUR concentrated in the core were formulated using the solvent evaporation method and were confirmed by Fourier transform infrared spectroscopy and nuclear magnetic resonance. Physicochemical characterization of F68–CUR conjugate micelles revealed that high drug loading content (DL%; 0.248 mg CUR/1 mg F68) was achieved, and the average particle size of micelles was 115.2 ± 3.0 nm. Compared with free CUR, a significantly higher cytotoxicity against human breast cancer cell line MDA-MB-231 was observed in F68–CUR conjugate micelles. The IC50 value of F68–CUR conjugate micelles was 1.95-fold lower than that of free CUR, indicating that the anti-cancer activity of CUR was significantly improved in the micelles. Furthermore, apoptotic studies demonstrated that F68–CUR conjugate micelles induced more cell apoptosis than that of free CUR. Taken together, these results demonstrate that F68–CUR conjugate micelles are promising to improve the clinical effectiveness of CUR in cancer treatment.

Polyethylenimine Modified and Non-Modified Polymeric Micelles Used for Nasal Administration of Carvedilol.

This study evaluates the ability of polyethylenimine-modified and non-modified polymeric micelles to enhance permeation through the nasal mucosa for a highly hydrophobic model drug. Carvedilol was loaded into polyethylenimine-modified and non-modified micelles by direct dissolution. Formulations were characterised by critical micelle concentration, micelle particle size and distribution, zeta potential, morphological structure and entrapment efficiency. The drug entrapment efficiency was determined to be as high as 77.14%, while micelle particle sizes and zeta potentials were within the range of 140.0-279.9 nm and (- 40.6)-(+ 25.9) mV, respectively. In vitro studies showed 100% release of carvedilol from micelles in 120 hours. Ex vivo permeation studies showed that the drug in polyethylenimine non-modified micelles passed more efficiently than the drug in polyethylenimine modified micelles. These results demonstrated that polyethylenimine modified micelles did not significantly affect the permeation of the drug when compared to polyethylenimine non-modified micelles. On the contrary, the drug in poly(L-lactide)-block-methoxy poly(ethylene glycol)5000 micelles, the polyethylenimine non-modified micelles, showed the highest permeation rate through bovine nasal mucosa. In conclusion, poly(L-lactide)-block- methoxy poly(ethylene glycol)5000 polymeric micelles maybe useful as novel drug carriers that increase the permeation through the nasal mucosa.

The effect of whey protein denaturation on light backscatter and particle size of the casein micelle as a function of pH and heat-treatment temperature

Reconstituted low-heat skim milk with pH adjusted to 6.3, 6.7, and 7.1 was heated at 80 and 90 °C for 10 min to evaluate the relationship between the attachment of denatured whey proteins to the surface of the casein micelle and the intensity of optical light backscatter response. Both optical light backscatter intensity and casein particle size showed a significant negative correlation with pH and positive correlation with heat treatment temperature. When samples were analysed independently by respective pH, there was a significant correlation of both light backscatter and particle size with temperature for samples at a pH of 6.3, and between light backscatter and temperature at pH 7.1. These results show the potential for the use of optical light backscatter techniques as a measurement of changes in casein micelle particle size induced by heat treatment.

Ginsenoside Rg3 bile salt-phosphatidylcholine-based mixed micelles: design, characterization, and evaluation.

20(R)-Ginsenoside Rg3 (G-Rg3) has good inhibition of tumor angiogenesis and anti-tumor effect. However, its poor aqueous solubility and liposolubility are not ideal for clinical applications. In this study, a G-Rg3 bile salt-phosphatidylcholine-based mixed micelle system (BS-PC-MMS) was prepared. The optimization of G-Rg3 BS-PC-MMS was carried out using response surface methodology based on a central composite design. The encapsulation efficiency (EE) and light transmission (LT) of the optimized formulation were 90.69±2.54% and 99.10±3.12%, respectively. The average particle size of micelles was 20 nm. To increase the stability of G-Rg3 BS-PC-MMS, the lyophilized formulation of micelles was prepared. The G-Rg3 BS-PC-MMS did not produce hemolysis of erythrocytes within a certain concentration range and exhibited a good inhibition of tumor cells. The chick embryo chorioallantoic membrane assay results showed that the G-Rg3 BS-PC-MMS significantly inhibited angiogenesis. The G-Rg3 BS-PC-MMS is thus shown to be a safe, stable, and promising drug delivery system.

Self-assembled micelles based on pH-sensitive PAE-g-MPEG-cholesterol block copolymer for anticancer drug delivery.

A novel amphiphilic triblock pH-sensitive poly(β-amino ester)-g-poly(ethylene glycol) methyl ether-cholesterol (PAE-g-MPEG-Chol) was designed and synthesized via the Michael-type step polymerization and esterification condensation method. The synthesized copolymer was determined with proton nuclear magnetic resonance and gel permeation chromatography. The grafting percentages of MPEG and cholesterol were determined as 10.93% and 62.02%, calculated from the area of the characteristic peaks, respectively. The amphiphilic copolymer was confirmed to self-assemble into core/shell micelles in aqueous solution at low concentrations. The critical micelle concentrations were 6.92 and 15.14 mg/L at pH of 7.4 and 6.0, respectively, obviously influenced by the changes of pH values. The solubility of pH-responsive PAE segment could be transformed depending on the different values of pH because of protonation–deprotonation of the amino groups, resulting in pH sensitivity of the copolymer. The average particle size of micelles increased from 125 nm to 165 nm with the pH decreasing, and the zeta potential was also significantly changed. Doxorubicin (DOX) was entrapped into the polymeric micelles with a high drug loading level. The in vitro DOX release from the micelles was distinctly enhanced with the pH decreasing from 7.4 to 6.0. Toxicity testing proved that the DOX-loaded micelles exhibited high cytotoxicity in HepG2 cells, whereas the copolymer showed low toxicity. The results demonstrated how pH-sensitive PAE-g-MPEG-Chol micelles were proved to be a potential vector in hydrophobic drug delivery for tumor therapy.

Differences in Several Important Proteins Contents between Raw Milk and Reconstituted Milk

The objective of this study was to evaluate the nutritional quality of reconstituted milk by determining concentrations of several important proteins. Difference in protein between raw milk and reconstituted milk was determined with spectrophotometer, HPLC, fluorometry, ELISA, photon correlation spectroscopy. Total undenatured whey protein, β-lactoglobulin, α-lactalbumin, chemically available lysine, insulin-like growth factor-Ⅰ (IGF-Ⅰ), epidermal growth factor (EGF), immunoglobulin G (IgG) contents and casein micelle size were analyzed for both raw milk and reconstituted milk. Results showed that reconstituted milk had a significant decrease (P&lt;0.01) in total undenatured whey protein, β-lactoglobulin, α-lactalbumin, chemically available lysine, IGF-Ⅰ, EGF and IgG. The decrease of casein micelle particle size confirmed that most of the whey protein denatured and associated with the casein micelle occurred in the processing of milk powder manufacture. It is concluded that reconstituted milk has a lower nutritional value than that of raw milk.