Micellar Characteristics Research Articles

The performance of hydrophilic moieties in synthesized fluorinated cationic surfactants on corrosion inhibition of carbon steel pipelines

Compared with traditional hydrocarbon surfactants, fluorinated surfactants exhibit unique characteristics such as reduced surface tension, enhanced efficacy in reducing interfacial tension, dual hydrophobic and oleophobic nature, increased thermal stability, and superior chemical resistance. These characteristics make them a favorite material for many kinds of applications. This study aims to highlight the synthetic route for three novel cationic fluorinated surfactants (CFS) and applied them in the oilfield as corrosion inhibitors. Characterization of the prepared surfactants took place using different spectroscopic techniques. The influence of hydrophilic moieties on the micellar characteristics of ionic surfactants that have the same hydrophobic fluorinated chains are investigated in this research. Also, an evaluation of the influence of these groups on thermodynamic parameters was carried out.The metal corrosion inhibition efficiency of the CFS was studied in acidic medium by three different techniques, including potentiodynamic polarization, electrochemical impedance spectroscopy (EIS), and weight loss procedures, at three different temperature ranges (25, 40, and 60 °C).The achieved results displayed the inhibition efficiency of the metal corrosion that was elevated by increasing both the CFS's concentration and the applied temperature values. The highest level of inhibition, reaching 97.48 %, was achieved at a concentration of 700 parts per million (ppm) and a temperature of 60 °C. Furthermore, it was noticed that the charge transfer resistance value was raised; however, the constant phase element was decreased with increasing the CFS concentrations. The CFS regards an excellent and mixed-type corrosion inhibitor. The adsorption of CFS has agreed the Langmuir's adsorption isotherm and was related to chemisorption. SEM photos show a good CS surface in the presence of CFS versus the absence of them.

Study the solute-solvent molecular interactions of L-Glutamine and conventional surfactants

The micellar characteristics of the three conventional surfactants such as sodium dodecyl sulfate (SDS), Hexadecyltrimethylammonium bromide (CTAB), and Triton X-100 (TX-100) are changed by the addition biologically active L-Glutamine (Glu) (i.e., 0.005, 0.01 and 0.02 M) were determined from stalagmometric, UV–visible spectroscopy, viscometric, FTIR and fluorescence methods using pyrene as probe. An observed decrease in I1/I3 in all micellar systems confirms the relative hydrophobicity of L-Glu. The CMCs values are reduced with the addition of L-Glu were determined by stalagmometric and it is confirmed by UV–visible and fluorescence methods and differs in the following order: SDS > CTAB > TX-100. The estimation of numerous interfacial parameters have also been done by using stalagmometric measurements including the (ϒCMC), (πCMC), (pC20), (Amin), and (Гmax). The concentration of L-Glu (M) rises, Amin values rise while the Гmax value falls and a significant rise in the surface tension of CMC (ϒCMC) values, with the values being in the range of 0.02 M > 0.01 M > 0.005 M > water. Hydrogen bonds, electrostatic interactions, hydrophobic interactions, and van der Waal interactions are only a few of the diverse types of interactions that were examined using FTIR in the pure surfactants and L-Glutamine mixed systems. To stabilize proteins and prevent protein aggregation, the findings presented here may be applied in pharmaceutical formulations.

Effect of biologically active amino acids based deep eutectic solvents on sodium dodecyl sulfate: A comparative spectroscopic study

Study the effects of three novel synthesized biologically deep eutectic solvents (DESs) on the micellar characteristics of anionic sodium dodecyl sulfate (SDS). The biologically active amino acids based three DESs synthesized have composed the 2:1 M of L-Aspartic acid (DES1), L-Tyrosine (DES2), L-Glutamine (DES3) and choline chloride, furthermore which characterized by FTIR. Surface tension, viscosity, UV–visible, fluorescence, and FTIR spectroscopy are a few of the techniques used to study the interactions of SDS within 5 and 10 wt% of three novel biological DESs in aqueous solutions. The presence and absence of 5 and 10 wt% of the three novel biological DESs in an aqueous solution is used to study the critical micelle concentration (CMC) and various interfacial characteristics including CMC, the efficiency of adsorption, the maximum surface excess concentration, the packing parameter, the minimum area per molecule, and the surface pressure at CMC, is assessed by the surface tension method. The calculated fluorescence data and those obtained using surface tension and UV–visible methods correspond well. The interactions that cause changes in the structure of the surfactant self-assemblies within aqueous DESs were investigated using FTIR technique. It is significant to highlight that the presence of unique biological DESs considerably facilitates the micellization process for SDS and the extent is more affinity for DES2 compared to DES1/DES3. The colloidal properties of DES and their combinations with water are anticipated to benefit from the current findings.

Effect of Oligomers and Polymers of Ethylene Glycols on Micellar Characteristics of Aqueous Solutions of Sodium Pentadectyl Sulfonate

The influence of oligomers and polymers of ethylene glycols with a different molecular mass on the structural transformations of aqueous solutions of surfactant, sodium pentadecylsulfonate, studied by viscometry and light scattering methods depending on their content in the system. It established that ethylene glycol with a molecular mass of 2,000 and 40,000 does not affect the structure of the system. For ethylene glycol with a molecular mass of 4,000, 6,000, and 20,000, a clearly expressed complex course of the dependence of the intrinsic viscosity of the micelle system on the polymer content was established. It assumed that with the changes in the concentration of ethylene glycols in the system, micelles are compacted due to a change in the balance of hydrophobic-hydrophilic interactions. In parallel with the change in apparent micelle masses and asymmetry coefficients determined by the light scattering method, the intrinsic viscosity also changes depending on the system's composition. The practical application of this research is that it allows the performance properties of sodium pentadecyl sulfonate (SPDS) to be adjusted, thereby expanding and improving its applications.

Investigation of effects of tropine-based surfactant structure on its thermal stability, foaming properties and solubilization

It has been shown that tropine-based ionic liquid surfactant (TILS) possesses exceptional biological, botanical, and pharmacological capabilities. Significantly, little research has been done on its essential characteristics, which are greatly influenced by its structural makeup. In this study, the essential properties, such as thermal stability, surface activity, foaming properties, and solubilization, were examined. The results demonstrate that the temperature stability of TILS was influenced by the nucleophilicity, coordination, and hydrophilicity of anions. Surface tension, solubility, and the HLB value of the TILS solution all worked together to affect the performance of the foam. The micellar and acid-base characteristics of TILS contributed to the solubilization of curcumin in its solution. The solubilization of curcumin in water was improved by TILS from 11 ng·mL−1 to more than 30 mgmmL−1, an increase of at least 106 times. These positive and adaptable physical and chemical characteristics highlight TILS potential in a variety of industrial-related applications.

Mixed Micelle Properties of Anionic Dimeric Surfactants with Anionic, Cationic, and Nonionic Surfactants

Herein, we have investigated the mixed micellar behavior of carboxylate anionic dimeric surfactants (CAD12 and CAD16) with commercial surfactants; anionic type i.e., sodium dodecyl sulfate, cationic i.e., cetyltrimethylammonium bromide and nonionic i.e., polyethylene glycol p-(1,1,3,3-tetramethylbutyl)-phenyl ether. The CMC values of mixed surfactants obtained from conductivity data decrease with a mole fraction of dimeric surfactants. The micellar characteristics (ideal CMC) and mutual interaction parameters (β) have been computed with the aid of theoretical models proposed by Clint, and Rubingh. In addition to this, thermodynamic parameters of micellization like 0 ΔG0mic, ΔH0mic, and ΔS0mic were evaluated and discussed.

Association behavior and physico-chemical parameters of a cetylpyridinium bromide and levofloxacin hemihydrate mixture in aqueous and additive media.

The investigation of the micellization of a mixture of cetylpyridinium bromide (CPB) and levofloxacin hemihydrate (LFH) was carried out by a conductivity technique in aqueous and aq. additive mixtures, including NaCl, NaOAc, NaBenz, 4-ABA, and urea. The aggregation behavior of the CPB + LFH mixture was studied considering the variation in additive contents and the change in experimental temperature. The micelle formation of the CPB + LFH mixture was examined from the breakpoint observed in the specific conductivity versus surfactant concentration plots. Different micellar characteristics, such as the critical micelle concentration (CMC) and the extent of counter ion bound (β), were evaluated for the CPB + LFH mixture. The CMC and β were found to undergo a change with the types of solvents, composition of solvents, and working temperatures. The ΔG0m values of the CPB + LFH system in aqueous and aq. additive solutions were found to be negative, which denotes a spontaneous aggregation phenomenon of the CPB + LFH system. The changes in ΔH0m and ΔS0m for the CPB + LFH mixture were also detected with the alteration in the solvent nature and solution temperature. The ΔH0m and ΔS0m values obtained for the association of the CPB + LFH mixture reveal that the characteristic interaction forces may possibly be ion-dipole, dipole-dipole, and hydrophobic between CPB and LFH. The thermodynamics of transfer and ΔH0m-ΔS0m compensation variables were also determined. All the parameters computed in the present investigation are illustrated with proper logic.

Novel approach for tuning micellar characteristics and rheology of a sulfate-free anionic surfactant sodium cocoyl glycinate

Amino acid based mild and sulfate-free anionic surfactant, sodium cocoyl glycinate (SCGLY) forms spherical micellar aggregates in water. The mixed micellar characteristics of SCGLY has been studied in the presence of nonionic surfactants like cocamide diethanolamine (CDEA) and lauryl glucoside (LG). The ternary aqueous system of SCGLY/CDEA/LG depicts higher surface activity and stronger aggregation ability compared to corresponding single or binary surfactant systems as revealed by tensiometry. The effect of pH (5.5–6.5) and total surfactant concentration (14–18 wt%) on thickening of SCGLY/CDEA/LG system is studied by rheology measurements. The presence of CDEA/LG amid charged SCGLY head group shrinks the electrostatic repulsion and induces sphere-to-rod micellar transition depicting low or moderate viscosity under as-prepared neutral pH. With alteration in pH, viscosity augmented to a maximum (at pH ~5.8) followed by a viscosity decrease. This is a novel finding for mild sulfate-free SCGLY surfactant solution which otherwise is very hard to thicken. Micellar size and charge is attained by dynamic light scattering, while micellar shapes and aggregation numbers are determined by small-angle neutron scattering (SANS) measurements. Moreover, foaming behavior (foamability and stability) and mildness property (zein solubility) of SCGLY can be optimized as per the necessity in the presence of CDEA and LG. This work might prove to be an innovative approach to tune the micellar characteristics and rheology of amino acid based surfactant formulation which could be extremely beneficial for cost-effective, thickener-free, sulfate-free surfactant systems used in cleansing composition with desired viscosity.

Effectiveness of micellization with polysorbate 80 on the in vitro bioaccessibility of various bioactives

The improvement in bioavailability of different compounds from PS80 micelles differs widely. This research, for the first time, investigated the effects bioactives, with different physicochemical properties (CoQ10, curcumin, catechin, naringenin, quercetin, β-carotene and retinyl palmitate), have on the micellar characteristics and the in vitro bioaccessibility of the loaded bioactives. There was no link between the physicochemical properties of the bioactives and the loading capacity of the PS80 micelles, which varied between 0.04 and 14.0%, or the average bioaccessibility of the bioactives, which varied between 14 and 86%. Not the ratio of loaded bioactive to PS80, but rather an increased concentration of PS80, increased the bioaccessibility of the loaded bioactive. It is not clear if differences were due to modifications of the PS80 micelles during the digestion process, where e.g. bile salts and/or phospholipids were incorporated into the micelles, or if the micelles totally dissociated and physiological mixed micelles were formed, including the PS80.

Dendritic core derived unimolecular micelles with poly(lactic acid) arms: Synthesis and application as a phase transfer agent

AbstractUnimolecular micelles refer to amphiphilic hyperbranched molecules, which exhibit micellar characteristics in a single molecule. In the present study, starting with pentaerythritol, three new dendrimers D1, D2, and D3 were synthesized in good yields bearing 9, 12, and 18 peripheral hydroxyl groups, respectively, using alkyne‐azide Husigen 1,3‐dipolar cycloaddition reaction. The structural integrity and purity of the dendrimers were confirmed by 1H and 13C NMR spectroscopy, and FE‐SEM studies established their near‐spherical morphology. Using D2 as a macroinitiator, hyperbranched 12‐arm star polymers were synthesized via ring‐opening polymerization of l‐lactide. The star polymer is found to be an efficient sequestering agent for water‐soluble dyes like congo red, bromophenol blue, and methyl orange from aqueous phase due to its amphiphilic nature demonstrating the application of unimolecular micelles in dye removal from aqueous waste.

Single and mixed Pluronics® micelles with solubilized hydrophobic additives: Underscoring the aqueous solution demeanor and micellar transition

This work aims to optimize the aqueous solution behavior in mixed system of polyethylene oxide-block-polypropylene oxide-block-polyethylene oxide (PEO-PPO-PEO). Two copolymers viz., P123 and F127 (with same size of hydrophobic PPO block and 30 % and 70 % hydrophilic PEO end blocks, respectively) were used and the changes in size self-assembled mixed micelles were examined in the presence of small amount of four very hydrophobic copolymers viz., L61, L81, L101, and L121 (each with 10 % PEO but varying PPO molecular weight). The cloud point (CP) show the changes in the phase behavior of the examined systems while the relative viscosity (ηrel) pointed out marked changes in the flow behaviour. The micellar characteristics (size, shape, aggregation number) determined by dynamic light scattering (DLS) and small-angle neutron scattering (SANS) depict the plausible morphological transition expressed as apparent hydrodynamic diameter (Dh), hard sphere radius (Rhs), aggregation number (Nagg) at different temperatures. Such modulations in the mixed Pluronics® systems are further examined for the solubilization of hydrophobic anticancer drug curcumin (Cur). The enhanced Cur solubility is well-established from the distinctive peak intensities as observed from UV–Visible (UV–vis) and Fourier Transform Infrared (FT-IR) spectral profile which validated the interaction of Cur with the examined copolymeric systems.

Drug anion based surface active ionic liquids: Molecular interactions, surface activity and micellization behavior in aqueous solutions

The design of surface active ionic liquids (SAILs) requires thorough understanding of interactions (in bulk as well as at molecular level) between the cation - anion pairs and their interaction with water molecules. These interactions determine the chemical & thermal stability, surface activity and micelle formation. In this work we examine the interactions in SAILs of type, 1-hexadecyl-1-methylpiperidinium or pyridinium acetylsalicylates (AcSa), [C16mpip or py][AcSa] and their precursors based on chloride and hydroxide anions by ATR–FTIR measurements and B3LYP level density functional calculations. The thermo-analytical, surface activity and micellar characteristics were assessed by DSC, dynamic TGA, surface tension, electrical conductivity, ITC, particle size analysis, small angle x-ray scattering, proton NMR and steady state fluorescence measurements. The interactions within the ion pairs are intensified with the increase in the size and complexity of the anion. The thermal stability was dependent on type of the anion and followed the order: AcSa > OH > Cl. AcSa based SAILs are effective and efficient in reducing the surface tension values of water. SAILs formed oblate ellipsoidal shaped micelles, that grow along the semi major axis with the increase in concentration.

The Micellization of Well-Defined Single Graft Copolymers in Block Copolymer/Homopolymer Blends.

A series of well-defined (polyisoprene)2(polystyrene), I2S, single graft copolymers with similar total molecular weights but different compositions, fPS, were blended with a low molecular weight polyisoprene homopolymer matrix at a constant concentration 2 wt%, and the micellar characteristics were studied by small-angle x-ray scattering. To investigate the effect of macromolecular architecture on the formation and characteristics of micelles, the results on the single graft copolymers were compared with those of the corresponding linear polystyrene-b-polyisoprene diblock copolymers, SI. The comparison reveals that the polystyrene core chains are more stretched in the case of graft copolymer micelles. Stretching turned out to be purely a result of the architecture due to the second polyisoprene block in the corona. The micellization of a (polystyrene)2(polyisoprene), S2I, graft copolymer was also studied, and the comparison with the results of the corresponding I2S and SI copolymers emphasizes the need for a critical core volume rather than a critical length of the core-forming block, in order to have stable micelles. Finally, the absence of micellization in the case of the I2S copolymer with the highest polystyrene volume fraction is discussed. For this sample, macrophase separation occurs, with polyisoprene cylinders formed in the copolymer-rich domains of the phase-separated blends.

Contrasting effect of 1-butanol and 1,4-butanediol on the triggered micellar self-assemblies of C16-type cationic surfactants.

The self-assembly in aqueous solutions of three quaternary salt-based C16-type cationic surfactants with different polar head groups and identical carbon alkyl chain viz., cetylpyridinium bromide (CPB), cetyltrimethylammonium tosylate (CTAT), and cetyltriphenylphosphonium bromide (CTPPB) in the presence of 1-butanol (BuOH) and 1,4-butanediol (BTD) was investigated using tensiometry, 2D-nuclear Overhauser enhancement spectroscopy (2D-NOESY) and small angle neutron scattering (SANS) techniques. The adsorption parameters and micellar characteristics evaluated at 303.15 K distinctly showed that BuOH promotes the mixed micelle formation while BTD interfered with the micellization phenomenon. The SANS data fitted using an ellipsoid (as derived by Hayter and Penfold using the Ornstein-Zernike equation and the mean spherical approximation) and wormlike micellar models offered an insight into the micelle size/shape and aggregation number (Nagg) in the examined systems. The evaluated descriptors presented a clear indication of the morphology transition in cationic micelles as induced by the addition of the two alcohols. We also offer an investigation into the acceptable molecular interactions governing the differences in micelle morphologies, using the non-invasive 2D-NOESY technique and molecular modeling. The experimental observations elucidated from computational simulation add novelty to this work. Giving an account to the structural complexity in the three cationic surfactants, the molecular dynamics (MD) simulation was performed for CPB micelles in an aqueous solution of alcohols that highlighted the micelle solvation and structural transition, which is further complemented in terms of critical packing parameter (PP) for the examined systems.

Micellar characteristics of an amphiphilic star-block copolymer in DES-water mixture

Deep eutectic solvents (DES) have revealed the ability to promote the aggregation of amphiphiles in solution. With a brief overview on the self-assembly of amphiphilic substances in protic/aprotic, polar/non-polar solvents, ionic liquids (ILs), and deep eutectic solvents, we herein report the aggregation behavior of a star block (4-arm) ethylene oxide (EO)-propylene oxide (PO) block copolymer (5 %w/v) tetronic T1304 in the presence of different DESs [ChCl: urea, ChCl: ethylene glycol (EG), ChCl: glycerol (Gly), ChCl: malonic acid (MA), ChCl: glutaric acid (GA), and ChCl: oxalic acid (OA)] in varying aqueous molar ratio solution. From high-sensitivity differential scanning calorimetry (HSDSC), surface tension (S.T.), small-angle neutron scattering (SANS), and dynamic light scattering (DLS), we present for the first time the self-aggregation and size distribution profile of amphiphilic tetronic T1304 in DES-water mixture system. The solubility of poorly water-soluble drug, quercetin (QN), was also checked in 5 %w/v copolymeric micelles and in presence of different DESs using UV-Visible spectroscopy. The presence of various DESs alter the micellization and micellar characteristics and such observed behavior are due to the favorable interactions that support the self-assembly in DES-water solvent mixture which is further elucidated by the molecular simulation study using the Gauss View 5.0.9.

Synthesis and characterization of castor oil-derived oxidation-responsive amphiphilic block copolymers: Poly(ethylene glycol)-b-poly(11-((2-hydroxyethyl)thio)undecanoate)

The synthesis of oxidation-responsive biodegradable amphiphilic block copolymers by Candida Antarctica Lipase B (CALB)-catalyzed self-polycondensation of 11-((2-hydroxyethyl)-thio)undecanoic acid (TEHA) initiated by methoxy polyethyleneglycol (mPEG-OH) of different molecular weights has been described. SEC and mono and bidimensional NMR have been used to confirm the molecular weight and structure of the polymers and copolymers. DSC and TGA have been employed to characterize their thermal properties. The oxidation behaviour in front of H2O2 as well as the structure of the oxidized products has been established using NMR, FTIR and Raman spectroscopies. The different block copolymers could self-assemble to form nanosized micelles in aqueous solution with low critical micelle concentration (CMC), showing potential application as dual responsive systems in drug delivery. Micellar characteristics were investigated by dynamic light scattering (DLS) and transmission electron microscopy (TEM). These micelles are prone to undergo a H2O2-triggered disassembly due to the oxidizable thioether groups in the hydrophobic core. Nile Red was used as model for hydrophobic drugs to test the oxidative triggered release of a copolymer, which showed progressive release in few hours upon the addition of H2O2.

Impact of Aromatic Counter-Ions Charge Delocalization on the Micellization Behavior of Surface-Active Ionic Liquids.

The nature of counter-ions governs the micellar and structural characteristics of surface-active ionic liquids (SAILs). Especially, the introduction of aromatic counter-ions significantly increases their surface adsorption and induces the formation of various types of aggregates like prolate ellipsoidal micelles, rodlike micelles, vesicles, lamellars, etc. The present study reports the role of charge delocalization of two different aromatic counter-ions in the micellization behavior of their respective SAILs in aqueous medium. For this purpose, we have synthesized two SAILs, namely, 1-tetradecyl-3-methylimidzolium phenolate [C14mim][PO] and 1-tetradecyl-3-methylimidzolium benzoate [C14mim][BZ]. The O-atom of phenolate (PO-) possesses negative charge, which is delocalized on its phenyl ring. Conversely, the negative charge of benzoate (BZ-) is not delocalized on its phenyl ring. The more hydrophobic BZ- counter-ion increases the hydrophobic interactions and reduces the electrostatic repulsions more efficiently as compared to PO-, which results in a lower critical micelle concentration (cmc) of [C14mim][BZ] than that of [C14mim][PO]. Interfacial properties obtained by tensiometry reveal better surface activity and absorption efficiency of [C14mim][BZ] as compared to [C14mim][PO]. The increase of cmc and degree of counter-ion binding (β) with the rise of temperature for both SAILs has been observed by conductometry. The decrease in the polarity of pyrene microenvironment explains the higher compactness of [C14mim][BZ] aggregates than that of [C14mim][PO], observed by fluorimetry. The position of PO- and BZ- is in the stern and palisade layers of C14mim+ aggregates, respectively, located by 1H NMR. The existence of prolate ellipsoidal micelles for both SAILs has been established by small-angle neutron scattering measurements. Thus, the interfacial and bulk properties of [C14mim][PO] lie somewhere in between those of the SAILs having perfect aromatic counter-ions, [C14mim][BZ], and the SAILs having regular inorganic counter-ions like Cl-, Br-, etc.

Solubilization of Carbamazepine in TPGS Micelles: Effect of Temperature and Electrolyte Addition.

D-α-Tocopheryl polyethylene glycol succinate (TPGS), a polyethylene glycol condensate, is a biologically important nonionic amphiphile. In this study, we report on aqueous solution behavior of TPGS with a focus on its clouding, surface activity, micellar characteristics, and solubilization capacity for a model hydrophobic drug, carbamazepine (CBZ). Micelles were characterized by dynamic light and small-angle neutron scattering studies as a function of temperature, salt addition, and CBZ solubilization. TPGS showed a cloud point of 78°C and possessed good surface activity (as observed from surface tension reduction and adsorption parameters). The critical micelle concentration (CMC), obtained from surface tension and fluorescence studies, was 0.02mM. Scattering studies showed formation of stable micelles (average diameter-12nm), exhibiting no significant changes in size upon salt addition (up to 1M NaCl), CBZ incorporation (up to 5mM), and temperature increase (40°C). Micelles in 5wt% TPGS showed about twentyfold enhancement in CBZ solubility. Considering the remarkable CBZ solubilization and its positioning in the core, we suggest that the formulation can be exploited as a sustained delivery vehicle.

Micellization of poly(2-vinylpyrridine)-b-poly(cyclohexyl methacrylate) (P2VP-b-PCHMA) block copolymers and their interpolymer complex formation in non-aqueous medium

HypothesisThe interpolymer complex formation between poly(vinylpyridine)-based polymers with poly(acrylic acid) (PAA), in aqueous or organic medium, is driven by the hydrogen-bonding complexation. Well-defined nanostructures, with specific practical applications, may be obtained by taking advantage of such non-covalent interactions. ExperimentsPoly(2-vinylpyridine)-b-poly(cyclohexyl methacrylate) (P2VP-b-PCHMA) and poly(2-vinylpyridine)-b-poly(t-butyl methacrylate)-b-poly(cyclohexyl methacrylate) (P2VP-b-PtBuMA-b-PCHMA) copolymers were synthesized by sequential anionic polymerization. Their micellar characteristics were examined as a function of their molecular characteristics in methylcyclohexane and toluene respectively, as cycloaliphatic and aromatic solvents for the selective solubilization of the PCHMA sequence. The size of interpolymer complexes was determined by DLS, in 1,4 dioxane, and their structural composition was characterized by 1H NMR. FindingsThe scaling relationship between the molecular composition and the micellar characteristics, such as particle size and aggregation number, could be established for the PCHMA-based copolymers in methylcyclohexane. It was further demonstrated that controlled micellization in 1,4 dioxane, as a non-selective organic solvent, could be achieved by hydrogen bond type interpolymer complex formation between P2VP-b-PCHMA and PAA-b-PCHMA under stoichiometric P2VP/PAA conditions. Finally, the size of the PCHMA-b-PAA/P2VP block copolymer/homopolymer complexes as well as of the PCHMA-b-PAA/PCHMA-b-P2VP block copolymer/block copolymer complexes was correlated with the molecular characteristics of the copolymers.

Dendron-Polymer Conjugate Based Cross-Linked Micelles: A Robust and Versatile Nanosystem for Targeted Delivery.

Among various nanomedicine platforms, biodegradable polymeric micelles offer a viable approach to targeted cancer therapy. Herein, we report fabrication of core-cross-linked micelles using dendron-polymer conjugates as building blocks. Hydrophobic polyester dendrons containing peripheral alkene groups are conjugated to a hydrophilic poly(ethylene glycol) based copolymer bearing activated ester groups for appending an amine-containing peptide based targeting group, namely, cRGDfK. Micellar constructs assembled in aqueous media were cross-linked using a tetra-thiol molecule via the photochemical thiol-ene reaction. Cross-linked and non-cross-linked micelles were compared in terms of their critical micellar concentration, stability, drug loading, and drug release characteristics. It was observed that the cross-linked micelles were stable upon excessive dilution compared to their non-cross-linked counterparts. Importantly, the amount of passive drug release in neutral pH was considerably lower for the cross-linked micellar systems. Furthermore, treatment of MDA-MB-231 breast cancer cells with nontargeted and targeted cross-linked micelles demonstrated higher internalization of the targeted construct. In corroboration, in vitro assay revealed that drug loaded targeted micelles possessed higher cytotoxicity than the nontargeted ones. Facile fabrication of this modular platform which can carry a desired therapeutic agent and be conjugated with appropriate targeting units, along with the attributes necessary to serve as a viable drug delivery system, offers a platform with potential for addressing various challenges in the field of micellar drug delivery.