Measurement Of Critical Micelle Concentration Research Articles

Design and Validation of Nanofibers Made of Self-Assembled Peptides to Become Multifunctional Stimuli-Sensitive Nanovectors of Anticancer Drug Doxorubicin.

Self-assembled peptides possess remarkable potential as targeted drug delivery systems and key applications dwell anti-cancer therapy. Peptides can self-assemble into nanostructures of diverse sizes and shapes in response to changing environmental conditions (pH, temperature, ionic strength). Herein, we investigated the development of self-assembled peptide-based nanofibers (NFs) with the inclusion of a cell-penetrating peptide (namely gH625) and a matrix metalloproteinase-9 (MMP-9) responsive sequence, which proved to enhance respectively the penetration and tumor-triggered cleavage to release Doxorubicin in Triple Negative Breast Cancer cells where MMP-9 levels are elevated. The NFs formulation has been optimized via critical micelle concentration measurements, fluorescence, and circular dichroism. The final nanovectors were characterized for morphology (TEM), size (hydrodynamic diameter), and surface charge (zeta potential). The Doxo loading and release kinetics were studied in situ, by optical microspectroscopy (fluorescence and surface-enhanced Raman scattering–SERS). Confocal spectral imaging of the Doxo fluorescence was used to study the TNBC models in vitro, in cells with various MMP-9 levels, the drug delivery to cells as well as the resulting cytotoxicity profiles. The results confirm that these NFs are a promising platform to develop novel nanovectors of Doxo, namely in the framework of TNBC treatment.

Isolation and Characterization of a Biosurfactant Producing Strain Planococcus sp. XW-1 from the Cold Marine Environment.

One cold-adapted strain, named Planococcus sp. XW-1, was isolated from the Yellow Sea. The strain can produce biosurfactant with petroleum as sole source of carbon at low temperature (4 °C). The biosurfactant was identified as glycolipid-type biosurfactant species by thin-layer chromatography (TLC) and Fourier transform infrared spectroscopy (FTIR). It reduced the surface tension of water to 26.8 mN/m with a critical micelle concentration measurement of 60 mg/L. The produced biosurfactant possesses high surface activity at wide ranges of temperature (−18–105 °C), pH values (2–12), and salt concentrations (1–18%). The biosurfactant exhibited higher surface activity and higher growth rate of cells with hexadecane and diesel as carbon source. The strain Planococcus sp. XW-1 was also effective in degrading crude oil, after 21 days of growth at 4 °C in medium with 1% crude oil and 1% (v/v) bacteria broth, 54% of crude oil was degraded. The results suggest that Planococcus sp. XW-1 is a promising candidate for use in the bioremediation of petroleum-contaminated seawater in the Yellow Sea during winter. This study reported for the first time that Planococcus isolated from the Yellow Sea can produce biosurfactant using petroleum as the sole carbon source at low temperature (4 °C), showing its ecological role in the remediation of marine petroleum pollution.

Effect of rhamnolipids on the fungal elimination of toluene vapor in a biotrickling filter under stressed operational conditions

The application of rhamnolipids in a fungal-cultured biotrickling filter (BTF) has a significant impact on toluene removal. Two BTFs were used; BTF-A, a control bed, and BTF-B fed with rhamnolipids. The effect of empty bed residence times (EBRTs) on toluene bioavailability was investigated. Removal of toluene was carried out at EBRTs of 30 and 60 s and inlet loading rates (LRs) of 23–184 g m−3 h−1. At 30 s EBRT, when inlet LR was increased from 23 to 184 g m−3 h−1, the removal efficiency (RE) decreased from 93% to 50% for the control bed, and from 94% to 87% for BTF-B. Increasing the EBRT simultaneously with inlet LRs, confirms that BTF-A was diffusion-limited by registering a RE of 62% for toluene inlet LR of 184 g m−3 h−1, whereas BTF-B, achieved RE > 96%, confirming a significant improvement in toluene biodegradability. Overall, the best performance was observed at 60 s EBRT and inlet LR of 184 g m−3 h−1, providing a maximum elimination capacity (EC) of 176.8 g m−3 h−1 under steady-state conditions. While a maximum EC of 114 g m−3 h−1 was observed under the same conditions in the absence of rhamnolipids (BTF-A). Measurements of critical micelle concentration showed that 150 mg L−1 of rhamnolipids demonstrated the lowest aqueous surface tension and maximum formation of micelles, while 175 mg L−1 was the optimum dose for fungal growth. Production rate of carbon dioxide, and dissolved oxygen contents highlighted the positive influence of rhamnolipids on adhesive forces, improved toluene mineralization, and promotion of microbial motility over mobility.

Can optical fiber compete with profile analysis tensiometry in critical micelle concentration measurement?

Abstract Critical micelle concentration (CMC) is one of the important nominal characteristics of the surfactants which can be measured using various methods. In this study, to detect the CMC of two ionic surfactants, cetyltrimethylammonium bromide (CTAB) and sodium dodecyl sulfate (SDS), two methods were utilized: (a) optical fiber and (b) drop profile analysis tensiometry (PAT) techniques. The spectrum width center and surface tension of the solutions at different concentrations of the surfactant were measured. The preliminary outcomes showed a compliance between optical fiber method and PAT technique. However, there were differences in the behavior of two surfactants in optical fiber measurement. In this method, when the solid surface of fiber is put in the system, the interactions between surfactant molecules and the fiber surface must be carefully considered.

Fabrication of Mixed Polymeric Micelles Based on Stimuli-Responsive Amphiphilic Copolymers for Drug Delivery and Controlled Release

In this report, mixed polymeric micelles (MPMs) system self-assembled from two kinds of cholesterol-grafted amphiphilic block copolymers cholesterol modified poly ([Formula: see text]-amino esters)-grafted disulfide poly (ethylene glycol) methyl ether (PAE(-ss-mPEG)-[Formula: see text]-Chol) and poly([Formula: see text]-amino ester)-g-poly(ethylene glycol) methyl ether-cholesterol (PAE-[Formula: see text]-mPEG-Chol) were prepared for drug delivery and controlled release with pH and redox-responsibilities. The self-assembly of two block copolymers was evaluated by measurement of critical micelle concentration (CMC) values using fluorescence spectroscopy. The hydrodynamic diameter, polydispersity index (PDI) and zeta-potential of MPMs in aqueous were recorded by dynamic light scattering (DLS) at different conditions. Doxorubicin (DOX) was efficiently encapsulated in the micellar core by the hydrophobic interaction. The drug loading content (LC) and encapsulation efficacy (EE) of MPMs with different formulations were evaluated. The DOX was released due to the swelling and disassembly of MPMs induced by low pH and high glutathione (GSH) concentrations. The in vitro results demonstrated that drug release rate and cumulative release were obviously dependent on pH values and reducing agents. The results showed that the MPMs could be the potential anticancer drug delivery carriers with pH/redox-triggered drug release profile.

Dehydration Determines Hydrotropic Ion Affinity for Zwitterionic Micelles.

Specific ion effects in zwitterionic micelles, especially for anions, are evident in reaction kinetics, zeta potential, and critical micelle concentration measurements. However, anion adsorption to zwitterionic micelles does not produce significant changes in shape, aggregation number, or interfacial hydration. Here we used molecular dynamics simulation of systems containing sulfobetaine zwitterionic micelles of N-dodecyl-N,N-dimethyl-3-ammonio-1-propanesulfonate (DPS) and nine different salts to explore ion adsorption in terms of group dehydration. Our results, in line with those obtained for cationic micelles, showed that the adsorption degree of anions containing both hydrophobic and hydrophilic portions, i.e., hydrotropes, were correlated with the ion dehydration and were governed mainly by the hydrophobic portion dehydration upon adsorption.

Influence of dimeric gemini surfactant micelles on the study of nickel-glycylleucine dipeptide and ninhydrin

Influence of dimeric gemini surfactant micelles on the study of nickel-glycylleucine dipeptide ([Ni(II)-Gly-Leu]+) and ninhydrin was carried out in the temperature ranging from 333 K to 353 K. An UV–vis spectrophotometer was employed to record the absorbance of product at definite time intervals. Rate of reaction was strongly catalyzed by the gemini surfactants. In the present reaction, the first-order dependence in metal-dipeptide complex and fractional-order dependence in ninhydrin were observed. For the measurements of critical micelle concentration (CMC), conductivity method was used. Rate constants (k ψ) increase and levelling-off regions are detected with [gemini] (just like conventional monocationic surfactant). Later, gemini produces a third region at higher [gemini] where, fast increment in k ψ is observed. The catalytic role of surfactants has been described below and above the CMC of gemini surfactants. From this study, binding constants of reactants and thermodynamic parameters have been evaluated. The kinetic results and observed catalysis could plausibly be rationalized by Menger and Portnoy’s pseudo-phase model of micellar catalysis.

Dual pH/Redox-Responsive Mixed Polymeric Micelles for Anticancer Drug Delivery and Controlled Release.

Stimuli-responsive polymeric micelles (PMs) have shown great potential in drug delivery and controlled release in cancer chemotherapy. Herein, inspired by the features of the tumor microenvironment, we developed dual pH/redox-responsive mixed PMs which are self-assembled from two kinds of amphiphilic diblock copolymers (poly(ethylene glycol) methyl ether-b-poly(β-amino esters) (mPEG-b-PAE) and poly(ethylene glycol) methyl ether-grafted disulfide-poly(β-amino esters) (PAE-ss-mPEG)) for anticancer drug delivery and controlled release. The co-micellization of two copolymers is evaluated by measurement of critical micelle concentration (CMC) values at different ratios of the two copolymers. The pH/redox-responsiveness of PMs is thoroughly investigated by measurement of base dissociation constant (pKb) value, particle size, and zeta-potential in different conditions. The PMs can encapsulate doxorubicin (DOX) efficiently, with high drug-loading efficacy. The DOX was released due to the swelling and disassembly of nanoparticles triggered by low pH and high glutathione (GSH) concentrations in tumor cells. The in vitro results demonstrated that drug release rate and cumulative release are obviously dependent on pH values and reducing agents. Furthermore, the cytotoxicity test showed that the mixed PMs have negligible toxicity, whereas the DOX-loaded mixed PMs exhibit high cytotoxicity for HepG2 cells. Therefore, the results demonstrate that the dual pH/redox-responsive PMs self-assembled from PAE-based diblock copolymers could be potential anticancer drug delivery carriers with pH/redox-triggered drug release, and the fabrication of stimuli-responsive mixed PMs could be an efficient strategy for preparation of intelligent drug delivery platform for disease therapy.

Al3+ enhanced room temperature phosphorescence of Pd-porphyrin resided in hybrid supramolecular gels and used for detection of trace Hg2+ ions

Micelle-hybridized supramolecular hydrogels were constructed through the self-assembly of gelator N,N-dibenzoyl-L-cystine (DBC) and micelles formed from a Gemini surfactant (G12-8-12). A phosphor, palladium meso-tetra (4-carboxyphenyl) porphyrin (Pd-TCPP) and Al3+ ions were loaded within the hybrid system. Interestingly, the room temperature phosphorescence (RTP) of Pd-TCPP can be efficiently enhanced and modulated by the concentration of Al3+ ions. The enhancement effect could be attributed to the interactions between Al3+ and DBC as well as porphyrin, which verified by 1H NMR analysis. The study of transmission electron microscopy and scanning electron microscopy indicated that a more compact 3D network structure of the gel system was formed upon the addition of Al3+. In addition, measurement of critical micelle concentration indicated that Al3+ ions increase the surface activity of G12-8-12 to promote micelle formation, thereby increasing the dispersion of Pd-TCPP in the hybrid gels. Based on the synergistic effect of these results, the non-radiative transition of Pd-TCPP was efficiently inhibited, resulting in highly efficient RTP. Furthermore, the enhanced RTP of as-prepared gel system shows potential application to detect trace Hg2+ ions because the RTP can be quenched by Hg2+. A linear relationship between RTP against the logarithmic concentration of Hg2+ was found over the range of 6 × 10−8 and 1 × 10−6 mol/L. The detection limit was found to be 0.017 nmol/L.

Synthesis and Properties of Low-Molecular-Weight PEI-Based Lipopolymers for Delivery of DNA.

Rapid enzymatic degradation and fragmentation during DNA administration can result in limited gene expression, and consequently, poor efficacy. It is necessary to use novel vectors for DNA delivery. Herein, we aimed to design useful carriers for enhancing transfection efficiency (TE). These lipopolymers were prepared through Michael addition reactions from low-molecular-weight (LMW) polyethyleneimine (PEI) and linkers with three kinds of steroids. Agarose gel electrophoresis assay results displayed that the three lipopolymers could condense plasmid DNA well, and the formed polyplexes had appropriate sizes around 200–300 nm, and zeta potentials of about +25–40 mV. The results of in vitro experiments using HeLa, HEK293, and MCF-7 cells showed that these lipopolymers present higher TE than 25-kDa PEI, both in the absence and presence of 10% serum. Flow cytometry and confocal microscopy studies also demonstrated that these lipopolymer/DNA complexes present higher cellular uptake and intracellular distribution. The measurement of critical micelle concentration (CMC) revealed that these lipopolymers could form micelles, which are suited for drug delivery. All results suggest that the three materials may serve as hopeful candidates for gene and drug delivery in future in vivo applications.

Synthesis, Surface Activity, and Antimicrobial Efficacy of Diaryliodonium Salt‐Derived Amphiphiles

AbstractTwo sets of 19 amphiphiles derived from diaryliodonium salt in the form of 4‐methylbenzenesulfonate salts and trifluoromethanesulfonate salts were synthesized in good yields through the oxidation of 17 different aryl iodides using oxone (potassium peroxymonosulfate) as the oxidation agent in Route I and meta‐chloroperoxybenzoic acid as the oxidation agent in Routes II and III, followed by Friedel–Crafts reaction with (2‐(2‐(2‐methoxyethoxy)ethoxy)ethoxy)benzene to obtain the target compounds (1–19). Their structures were characterized by 1H nuclear magnetic resonance (NMR), 13C NMR, and high‐resolution mass spectrometry studies. Their surface activities were evaluated on the basis of surface tension and critical micelle concentration measurements by the Wilhelmy plate method at 25 °C. With their good water solubility, diaryliodonium salts (1–19) have excellent short‐term bactericidal efficacy against Bacillus cereus in the concentration of 600 ppm at 20 °C. After compounding 1 or 18 with the broad‐spectrum but skin‐irritating antibacterial agent Kathon CG (methylchloroisothiazolinone in combination with methylisothiazolinone) in the ratio of 1:1 by mass, both formulations maintained lethality rate of >90% after 48 h.

Auric Chloride Induced Micellization on Fractal Patterned Dicationic Amphiphiles and Stabilization of Gold Nanoparticles.

The present article reports the development of sunlight-mediated rapid synthesis of bile acid derived dicationic amphiphiles, namely, dicationic cysteamine-conjugated cholic acid (DCaC), dicationic cysteamine-conjugated deoxycholic acid (DCaDC), and dicationic cysteamine-conjugated lithocholic acid (DCaLC) by adopting thiol–yne click chemistry approach. The auric chloride (AuHCl4) induced micellization of amphiphiles from fractal pattern to chainlike aggregates was examined by critical micelle concentration measurements, quenching studies, field emission scanning electron microscopy, and optical microscopy techniques. The micelles thus formed act as ideal templates for the stabilization of gold nanoparticles (AuNPs) and exhibit good stability for more than 6 months. The synthesized AuNPs were characterized using UV–visible spectroscopy, high-resolution transmission electron microscopy, DLS, zeta potential, and contact angle measurements. These NPs showed high salt tolerance, and the levels were found to be 420, 460, and 580 mM for DCaC-, DCaDC-, and DCaLC-capped AuNPs, respectively.

Ability of Sugar based Glucoside Surfactants to Remove Petroleum Contaminants

A study is carried out to evaluate the efficiency of synthesized sugar based alkyl polyglucosides (APG 10 , APG 12 , APG 14 ) for washing petroleum oil contaminants from soil in the shallow perched aquifers. Their efficiencies were compared with other commercially important non-ionic surfactants. viz. Tween-20, Tween-40 and Brij-58. The APG 10 was synthesized from anhydrous glucose and decyl alcohol in the presence of an acid catalyst in a cost effective manner. The spectroscopic tools viz, FTIR, NMR, thin layer and mass chromatographic techniques were used for structural elucidation of APG 10 . Based on the measurement of critical micelle concentration, the preferred concentrations of aqueous surfactant solutions for soil washing are determined. The batch washing experiments have shown that the oil removal efficiencies decrease in the following order APG 14 >Brij-58>APG 12 >APG 10 >Tween-40>Tween-20. Biodegradability test of the APG 10 have been carried out by modified OECD (Organization for Economic Cooperation&Development) screening method to evaluate its environmental compatibility. More than 90% surfactants are found to degrade within one week period in river water.

Alendronate-decorated biodegradable polymeric micelles for potential bone-targeted delivery of vancomycin

Osteomyelitis is a bone infection disease which is caused by bacteria or other germs, and could cause serious impact on the health and working capacity of the patients. Alendronate (ALN) can chelate strongly with the calcium ion of hydroxyapatite (HA) which is commonly used to treat osteoporosis. Nanomedicine has attracted a lot of attention in that the nano-sized carrier can deliver drug molecules to specific site of interest with the aid of targeting moiety and achieve sustained release, resulting in improved therapeutic effect and reduced side effect. In this study, micelles self-assembled from poly(lactic acid-co-glycolic acid)-block-poly(ethylene glycol)-alendronate (PLGA-PEG-ALN) copolymer were prepared for bone-targeted delivery of vancomycin (Van). The chemical structure of PLGA-PEG-ALN was confirmed by proton nuclear magnetic resonance (1H-NMR) spectroscopy. The formation of the nanoparticles was characterized by dynamic light scattering, transmission electronic microscopy as well as the critical micelle concentration measurement. Release profiles from the micelles revealed that the conjugation of ALN to the surface of micelle did not pose adverse effect on the drug-loading capacity and release behaviors. The cytotoxicity of Van-loaded PLGA-PEG-ALN micelles as well as the blank micelles was evaluated via 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay toward rat bone marrow stromal cells (rBMSCs) and human embryonic hepatocytes (L02 cells), and results showed that this Van-loaded micelle possesses appropriate cytotoxicity and is safe in the potential treatment of osteomyelitis. The in vitro affinity of PLGA-PEG-ALN micelles to the HA was also confirmed in vitro. The antibacterial effect of Van-loaded PLGA-PEG-ALN micelles was tested against Staphylococcus aureus (SA) which is the main pathogenic bacteria in osteomyelitis, and the results showed that the Van-loaded micelles can effectively inhibit the growth of SA. These results demonstrated that the PLGA-PEG-ALN micelles may be potentially used for the bone targeted delivery of Van.

3,3′-Dioctadecyloxacarbocyanine perchlorate (DiO) as a fluorogenic probe for measurement of critical micelle concentration

DiO is explored as a fluorogenic dye for CMC measurement, and we demonstrate that it is more user-friendly and reliable than the commonly used dye, Nile Red.

Structure-based study of antiamyloidogenic cyclic d,l-α-peptides

Protein misfolding and aggregation are the hallmarks of many devastating diseases. We have previously shown that cyclic d,l-α-peptide CP-2 reacts and stabilizes less toxic forms of amyloid β (Aβ), and protects the cells from Aβ-induced toxicity. Here, we performed extensive structure-based studies on CP-2 to elucidate the contribution of each residue to the total antiamyloidogenic activity and determine the interactions that are involved between CP-2 and Aβ. We showed that the hydrophobicity of CP-2 analogs correlates with their antiamyloidogenic potency, however, aromatic interactions are even more important for this activity. The antiamyloidogenic activity of CP-2 analogs also correlates with their ability to self-assemble, as shown by the critical micelle concentration measurements. The cell survival studies performed on rat pheochromocytoma PC-12 cells suggest that incorporation of an additional aromatic residue to the CP-2's sequence increases its protective effect against Aβ42-induced toxicity.

Pluronic P123-Docetaxel Conjugate Micelles: Synthesis, Characterization, and Antitumor Activity

The purpose of this research is to develop and evaluate Pluronic P123 (P123)-docetaxel (DTX) conjugate that could form core-shell-type micelles in aqueous solution. DTX was covalently conjugated to P123 via ester bond after the activation of DTX by succinic anhydride. The structure of P123-DTX conjugate was confirmed by 1H-NMR. The self-assembly behavior of the P123-DTX conjugate in aqueous solution was characterized by the measurement of critical micelle concentration (CMC). The CMC of P123-DTX conjugate was (1.34 +/- 0.05) x 10(-5) mol/L, which was lower than that of P123 ((1.91 +/- 0.07) x 10(-5) mol/L). The DTX content in the conjugate could reach 13.69% (wt.%). TEM and DLS analysis showed that the conjugate formed approximately spherical micelles with mean particle size of 85.3 +/- 1.59 nm. In vitro release of DTX from the conjugate micelles showed pH dependence, being faster at lower pH value than that at pH 7.4. In vitro cytotoxicity of P123-DTX conjugate micelles was evaluated by MTT method against HepG2, MCF-7 and B16 cell lines and the result indicated that P123-DTX conjugate micelles showed lower cytotoxicity than the DTX injection-Duopafei. Compared with Duopafei, in vivo antitumor activity of P123-DTX conjugate micelles in Kunming mice bearing B16 tumor was more effective and less toxic. These results indicated that the P123-DTX conjugate micelles prepared in this study may be considered as an alternative and promising DTX delivery system.

Oxime Linkage: A Robust Tool for the Design of pH-Sensitive Polymeric Drug Carriers

Oxime bonds dispersed in the backbones of the synthetic polymers, while young in the current spectrum of the biomedical application, are rapidly extending into their own niche. In the present work, oxime linkages were confirmed to be a robust tool for the design of pH-sensitive polymeric drug delivery systems. The triblock copolymer (PEG-OPCL-PEG) consisting of hydrophilic poly(ethylene glycol) (PEG) and hydrophobic oxime-tethered polycaprolactone (OPCL) was successfully prepared by aminooxy terminals of OPCL ligating with aldehyde-terminated PEG (PEG-CHO). Owing to its amphiphilic architecture, PEG-OPCL-PEG self-assembled into the micelles in aqueous media, validated by the measurement of critical micelle concentration (CMC). The MTT assay showed that PEG-OPCL-PEG exhibited low cytotoxicity against NIH/3T3 normal cells. Doxorubicin (DOX) as a model drug was encapsulated into the PEG-OPCL-PEG micelles. Drug release study revealed that the DOX release from micelles was significantly accelerated at mildly acid pH of 5.0 compared to physiological pH of 7.4, suggesting the pH-responsive feature of the drug delivery systems with oxime linkages. Flow cytometry and confocal laser scanning microscopy (CLSM) measurements indicated that these DOX-loaded micelles were easily internalized by living cells. MTT assay against HeLa cancer cells showed DOX-loaded PEG-OPCL-PEG micelles had a high anticancer efficacy. All of these results demonstrate that these polymeric micelles self-assembled from oxime-tethered block copolymers are promising carriers for the pH-triggered intracellular delivery of hydrophobic anticancer drugs.

Bioinspired core‐crosslinked micelles from thymine‐functionalized amphiphilic block copolymers: Hydrogen bonding and photo‐crosslinking study

AbstractBioinspired core‐bound polymeric micelles, based on hydrogen bonding and photo‐crosslinking, of thymine have been prepared from poly(vinylbenzylthymine)‐b‐poly(vinylbenzyltriethylammonium chloride). The amphiphilic block copolymer was synthesized by 2,2‐tetramethylpiperidin‐1‐oxyl‐mediated living radical polymerization in water/ethylene glycol solution. Micelle characterization and critical micelle concentration measurements demonstrated that the hydrogen bonding of the attached thymine units stabilizes the micelles. Further, core‐crosslinked polymeric micelles were formed by ultraviolet (UV) radiation showing that the stability of the micelle could be controlled by the UV crosslinking of the attached thymines. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011

Abstract 5293: Mixed micelles of triblock copolymers enhance delivery of indocyanine green for fluorescent tumor imaging

Abstract The goal of this study is to develop formulations for non-invasive, near-infrared detection of tumors. Indocyanine green (ICG) is an FDA-approved near-infrared (NIR) imaging agent that is clinically used for angiography and evaluation of liver function. ICG could potentially be used as a NIR fluorescence imaging agent for shallow tumors such as breast cancers. To fulfill this potential, formulations that improve the stability of ICG and direct its accumulation in tumors are necessary. We have previously described Pluronic F127 copolymer micelles that stabilize ICG, enhance its stability, and facilitate tumor accumulation in vivo after systemic administration. A major advantage of Pluronic F127 is its temperature-sensitive behavior that results in more stable micelle formulations at body temperature. However, Pluronic F127 micelles are not stable at room temperature, making micelle preparation and handling challenging. We hypothesized that mixed micelles formed from both Pluronic F127 and a temperature insensitive triblock copolymer composed of poly(ethylene oxide) and poly(3-hydroxybutyrate) (PEO-PHB-PEO), would result in micelles that are both easy to formulate at room temperature and that demonstrate increased stability at body temperature. Micelle formulations with various ratios of Pluronic F127: PEO-PHB-PEO were prepared and loaded with ICG. The micelle stability was determined by assessment of critical micelle concentration measurements, and time-course fluorescence assays were conducted to assess the ability of each micelle formulation to stabilize ICG fluorescence in buffer conditions. The ICG-loaded micelles were administered to tumor-bearing mice by tail vein injection and tumor localization was monitored by non-invasive fluorescence imaging in live mice. The polymer ratio used in micelle formulation was found to play a significant role in the ability of each preparation to stabilize ICG fluorescence Mixed micelles were found to enhance the stability of ICG fluorescence in buffer conditions, and CMC was shown to be dependent on polymer ratios. In vivo, mixed micelles were found to be more effective at maintaining ICG fluorescence in the bloodstream and achieved higher fluorescence signals in the tumor tissues compared with either PEO-PHB-PEO or Pluronic 127 micelles. These results suggest that the mixed micelle formulations offer a promising route to stabilizing these nanoparticles for improved delivery of NIR fluorescent contrast agents to tumors for imaging applications. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 5293. doi:10.1158/1538-7445.AM2011-5293