Fluorescence Probe Technique Research Articles

Synthesis and characterization of biotin modified cholesteryl pullulan as a novel anticancer drug carrier

A series of biotin modified cholesteryl pullulan (Bio-CHSP) conjugates with different degrees of substitution (DS) of biotin moiety were synthesized and characterized by Fourier transform infrared (FT-IR), proton nuclear magnetic resonance (1H NMR) and X-ray diffraction (XRD). Bio-CHSP conjugates were amphiphilic in nature and their self-aggregation behavior in aqueous media was evaluated by the fluorescence probe technique. Bio-CHSP self-aggregated nanoparticles (Bio-CHSP NPs) were prepared and analyzed by dynamic light scattering (DLS), zeta potential and transmission electron microscopy (TEM) technologies. These novel nanoparticles were almost spherical in shape, and their size, ranging from 178.8 to 100.0nm. The safety of Bio-CHSP NPs was studied through single dose toxicity test in mice, and the result showed that Bio-CHSP NPs were well tolerated at the intravenous dose of 200mg/kg in mice. Moreover, as a model anticancer drug, mitoxantrone loaded Bio-CHSP NPs were also prepared and characterized in this study.

Synthesis and self-assembly of a new amphiphilic thermosensitive poly(N-vinylcaprolactam)/poly(ε-caprolactone) block copolymer

New amphiphilic thermosensitive poly(N-vinylcaprolactam)/poly(e-caprolactone) (PNVCL-b-PCL) block copolymers were synthesized by ring-opening polymerization of e-caprolactone with hydroxy-terminated poly(N-vinylcaprolactam) (PNVCL-OH) as a macroinitiator. The structures of the polymers were confirmed by IR, 1H NMR and GPC. The critical micelle concentrations of copolymer in aqueous solution measured by the fluorescence probe technique reduced with the increasing of the proportion of hydrophobic parts, so did the diameter and distribution of the micelles determined by dynamic light scattering. The shape observed by transmission electron microscopy (TEM) demonstrated that the micelles are spherical. On the other hand, the UV–vis measurement showed that polymers exhibit a reproducible temperature-responsive behavior with a lower critical solution temperature (LCST). The LCST of PNVCL-OH can be adjusted by controlling the molecular weights, and that of copolymers can be adjusted by controlling the compositions and the concentration. Variable temperature TEM measurements demonstrated that LCST transition was the result of transition of individual micelles to larger aggregates.

Application of Fluorescent Probe Technique in Study of Polymer Self-Assembly

Application of Fluorescent Probe Technique in Study of Polymer Self-Assembly

PH-Responsive Supramolecular Vesicles Based on Water-Soluble Pillar[6]arene and Ferrocene Derivative for Drug Delivery

The drug delivery system based on supramolecular vesicles that were self-assembled by a novel host-guest inclusion complex between a water-soluble pillar[6]arene (WP6) and hydrophobic ferrocene derivative in water has been developed. The inclusion complexation between WP6 and ferrocene derivative in water was studied by (1)H NMR, UV-vis, and fluorescence spectroscopy, which showed a high binding constant of (1.27 ± 0.42) × 10(5) M(-1) with 1:1 binding stoichiometry. This resulting inclusion complex could self-assemble into supramolecular vesicles that displayed a significant pH-responsive behavior in aqueous solution, which were investigated by fluorescent probe technique, dynamic laser scattering, and transmission electron microscopy. Furthermore, the drug loading and in vitro drug release studies demonstrated that these supramolecular vesicles were able to encapsulate mitoxantrone (MTZ) to achieve MTZ-loaded vesicles, which particularly showed rapid MTZ release at low-pH environment. More importantly, the cellular uptake of these pH-responsive MTZ-loaded vesicles by cancer cells was observed by living cell imaging techniques, and their cytotoxicity assay indicated that unloaded vesicles had low toxicity to normal cells, which could dramatically reduce the toxicity of MTZ upon loading of MTZ. Meanwhile, MTZ-loaded vesicles exhibited comparable anticancer activity in vitro as free MTZ to cancer cells under examined conditions. This study suggests that such supramolecular vesicles have great potential as controlled drug delivery systems.

Dual Effects of Chitosan Decoration on the Liposomal Membrane Physicochemical Properties As Affected by Chitosan Concentration and Molecular Conformation

This study was devoted to a further understanding of the dependence of liposomal membrane properties on chitosan conformation and proved the dual effects of chitosan. The concentration dependence of chitosan conformation in aqueous solution was illustrated by surface tension and fluorescence probe techniques. Fluorescence and Raman spectra were subsequently employed to investigate the dynamic and structural changes of the liposomal membrane resulting from chitosan decoration. Results showed that the unfolded and crimped chains of chitosan flatly adsorbed onto the membrane surface via electrostatic attraction and favored liposome stability. Furthermore, the adsorption of crimped chains seemed stronger due to the embedding of their hydrophobic moieties. However, the presence of chitosan coils induced the increase in membrane fluidity, the intrachain disorder in lipid molecules, and the gauche conformation change of choline group. Dynamic light scattering and lipid oxidation measurements demonstrated that this perturbation was correlated with the permeation of coils into the lipid bilayer.

Synthesis and Microstructure Study of Polycarboxylated Superplasticizer with Different Carboxylic Group Content

Polycarboxylate-type superplasticizers (PCs) with different carboxylic group content and the same degree of polymerization are synthesized. Their microstructures are studied by fluorescent probe technique, dynamic light scattering (DLS) and transmission electron microscopy (TEM). The method of fluorescence probe confirms that there is the formation of hydrophobic microenvironment in PC solution, and PC with low carboxylic group content produces a stronger hydrophobic microenvironment than PC with high carboxylic group content. The DLS and TEM studies find that Z-Average diameters of aggregation produced by PC with low carboxylic group content is larger than that of aggregation produced by PC with high carboxylic group content. In addition, the shape of aggregation is not regular sphere. The reason for this is that association interaction of hydrogen bonding may occur among PC molecules or in the interior of single PC molecule.

Orientation and Birefringence Compensation of Trunk and Graft Chains in Drawn Films of Cellulose Acetate-graft-PMMA Synthesized by ATRP

We examined the molecular orientation and optical anisotropy that are induced by the stretching of cellulose acetate (CA)-graft-poly(methyl methacrylate) (PMMA) films, in connection with the side-chain contents. The copolymers were prepared by atom transfer radical polymerization. The molecular characterization was successfully performed by NMR and GPC analyses, before and after deliberate cleavage of the PMMA grafts. Even if the molecular weight of the grafts increased, the dispersity index remained below 1.2. The molecular orientation behavior in uniaxially drawn films of the copolymers was estimated by a fluorescence probe technique. The measurement revealed a declining tendency of the orientation development with an increase in degree of the molar substitution (MS) of MMA unit of the copolymers. In comparison of birefringence (Δn) at a given stage of elongation of the films, the value of Δn decreased rapidly with increasing MS, which eventually led to the conversion from a positive Δn for pristine CA (acetyl DS = 2.15) to a negative one for the composition containing >65 wt % PMMA that corresponded to the highest MS in the graft series used. This type of graft copolymer may deserve to be a high-functional material whose optical anisotropy is controllable variously in terms of birefringence compensation between the oriented trunk and graft chains.

Cell Volume Regulation in Cultured Human Retinal Müller Cells Is Associated with Changes in Transmembrane Potential

Müller cells are mainly involved in controlling extracellular homeostasis in the retina, where intense neural activity alters ion concentrations and osmotic gradients, thus favoring cell swelling. This increase in cell volume is followed by a regulatory volume decrease response (RVD), which is known to be partially mediated by the activation of K+ and anion channels. However, the precise mechanisms underlying osmotic swelling and subsequent cell volume regulation in Müller cells have been evaluated by only a few studies. Although the activation of ion channels during the RVD response may alter transmembrane potential (Vm), no studies have actually addressed this issue in Müller cells. The aim of the present work is to evaluate RVD using a retinal Müller cell line (MIO-M1) under different extracellular ionic conditions, and to study a possible association between RVD and changes in Vm. Cell volume and Vm changes were evaluated using fluorescent probe techniques and a mathematical model. Results show that cell swelling and subsequent RVD were accompanied by Vm depolarization followed by repolarization. This response depended on the composition of extracellular media. Cells exposed to a hypoosmotic solution with reduced ionic strength underwent maximum RVD and had a larger repolarization. Both of these responses were reduced by K+ or Cl− channel blockers. In contrast, cells facing a hypoosmotic solution with the same ionic strength as the isoosmotic solution showed a lower RVD and a smaller repolarization and were not affected by blockers. Together, experimental and simulated data led us to propose that the efficiency of the RVD process in Müller glia depends not only on the activation of ion channels, but is also strongly modulated by concurrent changes in the membrane potential. The relationship between ionic fluxes, changes in ion permeabilities and ion concentrations –all leading to changes in Vm– define the success of RVD.

Synthesis and characterization of novel brush copolymers with biodegradable polyphosphoester side chains for gene delivery

AbstractA novel kind of pH‐sensitive brush copolymer [poly(2‐hydroxyethyl methacrylate)‐graft‐poly(ethylethylene phosphate)]‐block‐poly[2‐(dimethylamino)ethyl methacrylate] [(PHEMA‐g‐PEEP)‐b‐PDMAEMA] with biodegradable polyphosphoester as the side chains, and its self‐assembled aggregates were developed for nonviral gene delivery. The brush copolymers were synthesized via a combination of single‐electron transfer living radical polymerization and ring‐opening polymerization. The chemical structures of these brush copolymers were characterized by FTIR, 1H NMR, and 31P NMR measurements. The critical aggregation concentration values of (PHEMA‐g‐PEEP)‐b‐PDMAEMA in pH 7.4 buffer solution were determined by the fluorescence probe technique. The interaction of (PHEMA‐g‐PEEP)‐b‐PDMAEMA and DNA was studied by agarose gel retardation assay, and the formed complexes were further investigated by means of zeta potential, dynamic light scattering, and transmission electron microscopy measurements. In addition, the in vitro cytotoxicity and transfection tests indicated that these brush copolymers showed low toxicity and favorable transfection efficiency to HeLa cells. All these results demonstrated that these biocompatible brush copolymers may be a promising candidate as nonviral polymeric gene vector. © 2013 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013

Synthesis of a well‐defined polyallene‐based amphiphilic graft copolymer via sequential living coordination polymerization and SET‐LRP

AbstractA well‐defined amphiphilic graft copolymer, poly(6‐methyl‐1,2‐heptadien‐4‐ol)‐g‐poly(2‐(dimethylamino)ethyl methacrylate) (PMHDO‐g‐PDMAEMA), has been synthesized by the combination of living coordination polymerization, single electron transfer‐living radical polymerization (SET‐LRP), and the grafting‐from strategy. PMHDO backbone containing double bonds and pendant hydroxyls was first prepared by [(η3‐allyl)NiOCOCF3]2‐initiated living coordination polymerization of 6‐methyl‐1,2‐heptadien‐4‐ol (MHDO) followed by treating the pendant hydroxyls with 2‐chloropropionyl chloride to give PMHDO‐Cl macroinitiator. SET‐LRP of 2‐(dimethylamino)ethyl methacrylate (DMAEMA) was performed in THF/H2O using PMHDO‐Cl as macroinitiator and CuCl/Me6TREN as catalytic system to afford the well‐defined PMHDO‐g‐PDMAEMA graft copolymer with a narrow molecular weight distribution (Mw/Mn = 1.28). The grafting density was as high as 92%. The critical micelle concentration (cmc) in water was determined by fluorescence probe technique and the micellar morphology was preliminarily explored by transmission electron microscopy. © 2013 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013

Preparation of stealth micellar nanoparticles of novel biodegradable and biocompatible brush copolymers with cholesteryl-modified PLA and PEG side chains

Novel amphiphilic brush copolymers, P(CPLAMA)-co-P(PEGMA), of cholesteryl poly(l-lactic acid) (CPLA) and poly(ethylene glycol) monomethyl ether (PEG) with determined hydrophobic/hydrophilic ratios were synthesized by the methacrylate (MA) macromonomer copolymerization method. Brush copolymers were prepared via both free radical polymerization (FRP) and atom transfer radical polymerization (ATRP). The copolymer compositions were determined by 1H NMR spectroscopy. The synthesized copolymers were used to prepare the micellar nanoparticles with hydrophobic CPLA and hydrophilic PEG forming the core and shell, respectively. The critical micelle concentration (CMC) values of the samples produced by FRP (brush copolymer 1) and ATRP (brush copolymer 2) were estimated to be approximately 0.9 and 0.7 mg/L in aqueous solution by a fluorescence probe technique, respectively. The transmission electron microscopy (TEM) images of micelles of the brush copolymers 1 and 2 showed that micelles were spherical in shape with a mean diameter of 111 and 32 nm, respectively. The results showed that the size of micelles became larger with the increase of the molecular weight of polymer and the relative content of the hydrophilic PEG as well. The drug loading efficiency and drug-releasing properties of the micelles were investigated by using naproxen as a hydrophobic model drug. The in vitro release of naproxen-loaded micelles with about 85–89 % loading efficiency and 17–18 % loading capacity was studied by a using dialysis method in phosphate-buffered solution at 37 °C. The drug-releasing characteristics exhibited a phase of slow release. On the basis of the results obtained, the proposed brush copolymers may be useful in various targeted drug delivery applications, especially those involving hydrophobic drugs.

Self-assembled micellar nanoparticles of a novel amphiphilic cholesteryl-poly(l-lactic acid)-b-poly(poly(ethylene glycol)methacrylate) block-brush copolymer

The biodegradable cholesteryl-(l-lactic acid) n (CPLA) was synthesized via ring opening polymerization of l-lactide in the presence of cholesterol as an initiator and the catalytic amount of Sn(Oct)2. The resulting monohydroxyl-terminated CPLA was subsequently converted to a bromine-ended macroinitiator (CPLA-Br) by esterification with 2-bromoisobutyryl bromide. Amphiphilic block-brush copolymers with different lengths of hydrophilic block (CPLA-b-P(PEGMA)4 and CPLA-b-P(PEGMA)12) were synthesized in a subsequent atom transfer radical polymerization of the poly(ethylene glycol)monomethyl ether methacrylate (PEGMA). The prepared polymers were characterized by FTIR, 1H NMR and GPC. The self-assembly of the copolymers into the micellar aggregates in aqueous media was followed with dynamic light scattering, transmission electron microscopy and fluorescence analysis. The CMC values of the CPLA-b-P(PEGMA)4 and CPLA-b-P(PEGMA)12 samples were estimated approximately 56 × 10−4 and 72 × 10−4 g/L in an aqueous solution by fluorescence probe technique, respectively. The hydrophobic/hydrophilic chain ratio of the amphiphilic copolymers could have demonstrated a correlation with micelle formation ability and inter-micellar aggregation in an aqueous solution. Using the naproxen as a hydrophobic model drug, the drug-loading efficiency and drug release properties of the CPLA–PEG nanoparticles were investigated. In vitro release study of the naproxen-loaded micelles with about 54–60 % loading efficiency and 11–12 % loading capacity was performed using dialysis method in phosphate-buffered solution at 37 °C. Accordingly, these polymeric micelles may be provided as an effective drug carrier for drug controlled release by modulating the copolymer composition and molecular weight of blocks.

SET-LRP synthesis of novel polyallene-based well-defined amphiphilic graft copolymers in acetone

A series of polyallene-based well-defined amphiphilic graft copolymers consisting of hydrophobic poly(6-methyl-1,2-heptadiene-4-ol) (PMHDO) backbone and hydrophilic poly(2-(dimethylamino)ethyl acrylate) (PDMAEA) side chains, was synthesized by the combination of living coordination polymerization and single-electron transfer living radical polymerization (SET-LRP). A double-bond-containing PMHDO backbone with pendant hydroxyls was prepared via [(η3-allyl)NiOCOCF3]2-initiated living coordination polymerization of a hydroxyl-containing allene derivative, 6-methyl-1,2-heptadiene-4-ol (MHDO). The pendant hydroxyls in the homopolymer were then treated with 2-chloropropionyl chloride to provide the PMHDO-Cl macroinitiator. Finally, the target PMHDO-g-PDMAEA well-defined graft copolymers were constructed through the grafting-from technique via SET-LRP of 2-(dimethylamino)ethyl acrylate (DMAEA) in acetone, a nonpolar solvent, initiated by the macroinitiator using CuCl/Me6TREN as catalytic system. The narrow molecular weight distributions (Mw/Mn ≤ 1.18) and kinetics experiment showed the controllability of SET-LRP graft copolymerization of DMAEA. The critical micelle concentrations (cmc) of PMHDO-g-PDMAEA amphiphilic graft copolymers in aqueous solution were determined by fluorescence probe technique and the dependence of cmc on pH or salinity were also investigated. Micellar morphologies were visualized using transmission electron microscopy.

Formation mechanism of CdS nanoparticles with tunable luminescence via a non-ionic microemulsion route

We investigated the synthesis of CdS nanoparticles via an optimized water-in-oil microemulsion route that used the non-ionic surfactant-based system H2O–n-octane–Brij30/1-octanol. For that purpose, a microemulsion that contained Cd(II) ions (μe1) and another microemulsion that contained S2− ions (μe2) were combined. To investigate the ways in which the non-ionic microemulsion characteristics controlled the size and emission properties of colloidal CdS quantum dots, μe1 and μe2 with tunable and robust similar structure were prepared. This requirement was fulfilled by matching the water emulsification failure boundary (wefb) of the two microemulsions and carrying out synthesis along this boundary. Dynamic light scattering and fluorescence probe techniques were used to investigate the size and interfacial organization of the microemulsion water droplets, and the CdS nanoparticles were characterized by UV–Vis and static fluorescence spectrometry, TEM and HRTEM. Nanoparticles of diameter 4.5–5.5 nm exhibiting enhanced band edge emission were produced by increasing the water content of the precursor microemulsions. The experimental results were combined with a Monte Carlo simulation approach to demonstrate that growth via coagulation of seed nuclei represented the driving mechanism for the CdS nanoparticle formation in the water-in-oil microemulsion.

Evaluation of a novel real-time fluorescent polymerase chain reaction assay for high-risk human papilloma virus DNA genotypes in cytological cervical screening

It has been confirmed that detection of high-risk human papillomavirus (HR HPV) DNA is useful in cervical cancer (CC) screening. Recently, a new real-time fluorescent polymerase chain reaction (PCR) assay was developed to detect HR HPV. This assay can synchronize nucleic acid amplification and testing using specific primers for 13 types of HR HPV genomes, combined with specific TaqMan fluorescent marker probe techniques through the fluorescence automatic PCR instrument. Furthermore, it uses TaqGold™ DNA polymerase, which minimizes the amount of non-specific amplification and increases the sensitivity of the assay. The aim of this study was to evaluate the analytical and clinical performance of the real-time fluorescent PCR assay in CC screening, compared to the Qiagen Hybrid Capture® II High-Risk HPV DNA test® (HC II). In total, 1,252 cervical specimens were collected from women between 19 and 71 years of age. The specimens were examined with three different assays, real-time fluorescent PCR assay and HC II for HR HPV detection combined with liquid-based cytology. Women with cytological abnormalities or HR HPV-positive results underwent colposcopy and cervical biopsy. This study demonstrated good overall agreement between HC II and real-time fluorescent PCR assay (overall agreement, 92.25%; Cohen's κ=0.814). For the detection of high-grade cervical intraepithelial neoplasias (CIN) and CC, the sensitivity of HC II and real-time fluorescent PCR was 94.48 and 92.82%, respectively, and the negative predictive value was 98.85 and 98.54%, respectively. High HR HPV infection rate of the high-grade CIN and CC group was detected (P<0.05). In conclusion, real-time fluorescent PCR assay provides similar results compared to the HC II test for HR HPV detection and could be used in CC screening in clinic.

SET‐LRP synthesis of PMHDO‐g‐PNIPAM well‐defined amphiphilic graft copolymer

AbstractA well‐defined amphiphilic graft copolymer, consisting of hydrophobic polyallene‐based backbone and hydrophilic poly(N‐isopropylacrylamide) (PNIPAM) side chains, was prepared by the combination of living coordination polymerization, single electron transfer‐living radical polymerization (SET‐LRP), and the grafting‐from strategy. First, the double‐bond‐containing backbone was prepared by [(η3‐allyl)NiOCOCF3]2‐initiated living coordination polymerization of 6‐methyl‐1,2‐heptadiene‐4‐ol (MHDO). Next, the pendant hydroxyls in every repeating unit of poly(6‐methyl‐1,2‐heptadiene‐4‐ol) (PMHDO) homopolymer were treated with 2‐chloropropionyl chloride to give PMHDO‐Cl macroinitiator. Finally, PNIPAM side chains were grown from PMHDO backbone via SET‐LRP of N‐isopropylacrylamide initiated by PMHDO‐Cl macroinitiator in N,N‐dimethylformamide/2‐propanol using copper(I) chloride/tris(2‐(dimethylamino)ethyl)amine as catalytic system to afford PMHDO‐g‐PNIPAM graft copolymers with a narrow molecular weight distribution (Mw/Mn = 1.19). The critical micelle concentration (cmc) in water was determined by fluorescence probe technique and the effects of pH and salinity on the cmc of PMHDO‐g‐PNIPAM were also investigated. The micellar morphology was found to be spheres using transmission electron microscopy. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013

Physicochemical Characterization and Self-Assembly Studies on Cationic Surfactants Bearing mPEG Tail

Poly(ethylene glycol), PEG, is normally coupled to hydrophobic molecules to produce nonionic surfactants. However, there is no report so far on cationic surfactants in which PEG chain acts as a hydrophobic tail. In this work, two novel cationic amphiphiles containing a poly(ethylene glycol) monomethyl ether (mPEG) tail of different lengths linked to a cationic headgroup were synthesized to investigate their surface activity and self-assembling properties. The amphiphiles were shown to be surface-active with low critical micelle concentration (cmc). It has been found that although mPEG chain is hydrophilic as compared to hydrocarbon chain of equivalent length, the cmc values are lower than that of cetyltrimethylammonium chloride, a commercial cationic surfactant. The cationic surfactants have been shown to have antimicrobial activity. The fluorescence probe studies and the thermodynamic data have shown that the self-assembly is due to strong van der Waals interaction between mPEG chains as well as hydrophobic effect. The single-tailed cationic surfactants spontaneously self-assembled to form small unilamellar vesicles with hydrodynamic diameter in the range of 20-50 nm. The vesicles were characterized by fluorescence probe technique, dynamic light scattering, transmission electron microscopy, and confocal fluorescence microscopy. We have also studied encapsulation of model drugs by the vesicles and pH-triggered release kinetics.

Study on Microstructures of Polycarboxylate-Type Superplasticizers with Different Side Chains

Polycarboxylate-type superplasticizers with different side chains and approximative degree of polymerization are synthesized. The microstructures of Polycarboxylate-type superplasticizers in water are studied by fluorescent probe technique, dynamic light scattering (DLS), transmission electron microscopy (TEM) and the self-assembly technique. The results indicate that the formation of hydrophobic microenvironment in PC solution is confirmed. The higher the ratio of long side chains of PC, the stronger the hydrophobic microenvironment formed in PC solution. The Z-Average diameters of aggregation formed in PC solution increase with the increasing of long side chains content. In addition, the size and shape of aggregation is not of uniform distribution, and the reason for this is that association interaction of hydrogen bonding occurs among PC molecules or in the interior of single PC molecule.

Nanosized micelles self-assembled from amphiphilic poly(citric acid)–poly(ε-caprolactone)–poly(citric acid) copolymers

In this study, novel ABA-type amphiphilic copolymers consisting of poly(citric acid) (PCA) (A) as hydrophilic segment and poly(e-caprolactone) (PCL) (B) as hydrophobic block were prepared by an approach in the following two steps: (1) ring-opening polymerization (ROP) of e-caprolactone with 1,5-pentanediol initiator to obtain a hydroxyl telechelic PCL; (2) melt polycondensation reaction of hydroxyl telechelic PCL and citric acid molecules. The prepared copolymers are capable of self-assembling into nanosized micelles in aqueous solution. The influence of the copolymer composition on the micelle dimensions was investigated. The critical micellar concentration of the copolymers is in the range of 5–6.3 × 10−2 mg/mL which is determined by the fluorescence probe technique using pyrene. Also the results indicate that CMC of self assembled micelles is influenced by the hydrophilicity of PCA–PCL–PCA copolymers depending on the CA/CP ratio, and these micelles may find great potential as drug carriers in biomedical fields.

Unprecedented diverse nanostructures formed by amphiphilic graft copolymer bearing PEO side chains synthesized by ATNRC

AbstractA series of well‐defined amphiphilic graft copolymers bearing hydrophilic poly(ethylene oxide) (PEO) side chains with tunable grafting densities were synthesized by atom transfer nitroxide radical coupling (ATNRC) reaction using CuBr/PMDETA as catalytic system via the grafting‐onto strategy. PEO side chains were linked to α‐C of carbonyl of polyacrylate‐based backbone, not to the ester side groups as usual, so that every repeating unit of the backbone possessed a pendant steric bulky tert‐butyl group. The critical micelle concentrations of the obtained amphiphilic graft copolymers in aqueous media determined by fluorescence probe technique using pyrene as probe increased with the raising of molecular weights. These amphiphilic graft copolymers with novel chemical structure showed unprecedented diverse nanostructures visualized by transmission electron microscopy in aqueous media and micellar morphologies varied with the changing of experiment parameters. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012