Core-shell Micelles Research Articles

Micellization and sol-gel transition of novel thermo- and pH-responsive ABC triblock copolymer synthesized by RAFT

A well-defined thermo- and pH-responsive ABC-type triblock copolymer monomethoxy poly(ethylene glycol)-b-poly(2-(2-methoxyethoxy) ethyl methacrylate-co-N-hydroxymethyl acrylamide)-b-poly(2-(diethylamino) ethyl methacrylate), mPEG-b-P(MEO2MA-co-HMAM)-b-PDEAEMA, was synthesized by reversible addition-fragmentation chain transfer polymerization (RAFT). The ABC-type triblock copolymer was endowed thermo- and pH-responsive, corresponding to the thermosensitive properties of P(MEO2MA-co-HMAM) and pH-responsive properties PDEAEMA segments, respectively. The thermo- and pH-responsive properties of copolymer aqueous solutions were studied by UV transmittance measurements, dynamic light scattering (DLS), transmission electron microscopy (TEM). The results showed that the N-hydroxymethyl acrylamide (HMAM) content in triblock copolymer affected the lower critical solution temperature (LCST) of the triblock copolymer aqueous solution. The copolymer self-assembled into core-shell micelles, with the thermoresponsive P(MEO2MA-co-HMAM) block and the hydrophilic PEG block as the shell, the hydrophobic PDEAEMA block as the core, in alkaline solution at room temperature. While in acidic media, when the temperature above the lower critical solution temperature (LCST) of the triblock copolymer aqueous solution, the copolymer self-assembled into P(MEO2MA-co-HMAM)-core micelles with mixed hydrophilic PEG and pH-responsive PDEAEMA coronas. Sol-gel transition temperature (Tsol-gel) for the triblock copolymer determined by vial inversion test further indicated that it is dependent on the concentration of the triblock copolymers and solution pH. Copolymer hydrogel loaded with bovine serum albumin (BSA) were used for the sustained release study. The results indicated that the hydrogel was a promising candidate for controlling protein drug delivery.

Reduction-responsive shell cross-linked micelles derived from amphiphilic triblock copolymer as anticancer drug delivery carrier

Stimuli-responsive crosslinked micelles are attractive carriers for in vivo delivery of water-insoluble therapeutic drugs due to their excellent stability during the blood circulation and high therapeutic effect resulting from the intelligent break-up of the crosslinked structure triggered by intracellular conditions as well as the subsequent fast drug release. Herein, novel amphiphilic triblock copolymer poly(l-lactide)-b-poly(allyl glycidyl ether/propanedithiol)-b-poly(ethylene glycol) (PLLA-b-P(AGE-SH)-b-PEG) was designed and synthesized by combining two successive ring-opening polymerizations and subsequent “thio-ene” reaction. Due to their unique amphiphilic architecture, copolymer PLLA-b-P(AGE-SH)-b-PEG could self-assemble into core-shell micelles, and the stimuli-responsive crosslinked micelles (SCMs) were obtained by crosslinking the P(AGE-SH) segments in the micellar shell under redox condition. The SCMs exhibited good stability against extensive dilution and slow sustained drug release in a simulated normal physiologycal environment, but fast release in the presence of GSH. As revealed by the cytotoxicity assay, the micelles from the copolymer PLLA-b-P(AGE-SH)-b-PEG showed excellent biocompatibility against HEK293T cells. Due to these combined good properties, the stimuli-responsive crosslinked micelles from PLLA-b-P(AGE-SH)-b-PEG are proposed to be an ideal carrier for the in vivo delivery of water-insoluble therapeutics.

Structure of Phospholipid Mixed Micelles (Bicelles) Studied by Small-Angle X-ray Scattering.

Mixed phospholipid micelles (bicelles) are widely applied in nuclear magnetic resonance (NMR) studies of membrane proteins in solution, as they can solubilize these proteins and provide a membrane-like environment. In this work, the structure of bicelles of dihexanoyl phosphatidyl choline (DHPC) and dimyristoyl phosphatidyl choline (DMPC) at different ratios was determined by small-angle X-ray scattering (SAXS) at 37 °C. Samples with concentrations as applied for NMR measurements with 28 wt % lipids were diluted to avoid concentration effects in the SAXS data. The DMPC/DHPC ratio within the bicelles was kept constant by diluting with solutions of finite DHPC concentrations, where the concentration of free DHPC is the same as in the original solution. Absolute-scale modeling of the SAXS data using molecular and concentration constraints reveals a relatively complex set of morphologies of the lipid aggregates as a function of the molar ratio Q of DMPC to DHPC. At Q = 0 (pure DHPC lipids), oblate core-shell micelles are present. At Q = 0.5, the bicelles have a tablet-shaped core-shell cylindrical form with an ellipsoidal cross section. For Q = 1, 2, 3.2, and 4, the bicelles have a rectangular cuboidal structure with a core and a shell, for which the overall length and width increase with Q. At Q = ∞ (pure DMPC), there is coexistence between multilamellar structures and free bilayers. For Q = 1-4, the hydrocarbon core is relatively narrow and the headgroup thickness on the flat areas is larger than that of, respectively, pure DHPC and DMPC, suggesting some mixing of DHPC into these areas and staggering of the molecules. This is further supported by comparisons of the ratio of the areas of rim and flat parts and estimates of the composition of the flat areas.

Polymer/silica hybrid hollow nanoparticles with channels and thermo-responsive gatekeepers for drug storage and release

Polymer/silica hybrid hollow nanoparticles (PSHNs) with channels and thermo-responsive gatekeepers for drug storage and on-off release were successfully synthesized using core-shell polymeric micelles of poly(N-isopropylacrylamide)-b-poly(4-vinylpyridine) (PNIPAM-b-P4VP) as a template. The core cavity was easily obtained using a thermo-responsive PNIPAM polymer without the application of calcination techniques. PSHNs featuring channels and thermo-responsive gatekeepers formed due to the swollen and soluble PNIPAM segment. The void volume and thickness shell of the PSHNs could be tuned by adjusting the pH value and temperature of the solution, as well as the mean polymeric micelle diameter and the molar ratio of TMOS to P4VP. Doxorubicin (DOX) was used as a model drug loaded into the PSHNs. A high drug loading content was achieved due to the hollow core and large surface area of the PSHNs.

Core-Shell Interface-Oriented Synthesis of Bowl-Structured Hollow Silica Nanospheres Using Self-Assembled ABC Triblock Copolymeric Micelles.

Hollow porous silica nanospheres (HSNs) are emerging classes of cutting-edge nanostructured materials. They have elicited much interest as carriers of active molecule delivery due to their amorphous chemical structure, nontoxic nature, and biocompatibility. Structural development with hierarchical morphology is mostly required to obtain the desired performance. In this context, large through-holes or pore openings on shells are desired so that the postsynthesis loading of active-moleculeonto HSNs via a simple immersion method can be facilitated. This study reports the synthesis of HSNs with large through-holes or pore openings on shells, which are subsequently termed bowl-structured hollow porous silica nanospheres (BHSNs). The synthesis of BHSNs was mediated by the core-shell interfaces of the core-shell corona-structured micelles obtained from a commercially available ABC triblock copolymer (polystyrene- b-poly(2-vinylpyridine)- b-poly(ethylene oxide) (PS-P2VP-PEO)). In this synthesis process, polymer@SiO2 composite structure was formed because of the deposition of silica (SiO2) on the micelles' core. The P2VP block played a significant role in the hydrolysis and condensation of the silica precursor, i.e., tetraethylorthosilicate (TEOS) and then maintaining the shell's growth. The PS core of the micelles built the void spaces. Transmission electron microscopy (TEM) images revealed a spherical hollow structure with an average particle size of 41.87 ± 3.28 nm. The average diameter of void spaces was 21.71 ± 1.22 nm, and the shell thickness was 10.17 ± 1.68 nm. According to the TEM image analysis, the average large pore was determined to be 15.95 nm. Scanning electron microscopy (SEM) images further confirmed the presence of large single pores or openings in shells. These were formed as a result of the accumulated ethanol on the PS core acting to prevent the growth of silica.

Preparation and characterization of anti-tubercular drugs encapsulated in polymer micelles

The aim of the present study is to encapsulate antitubercular drugs Rifampicin (RIF) and Isoniazid (INH) in core-shell micelles of ethylene oxide-propylene oxide (EO-PO) triblock copolymers, Pluronics® (P84, P85, P103, P105, P123 and F127). The formulations were characterized using FTIR, which showed no chemical or physical interaction of drugs with polymers. In vitro release profiles of drugs using different kinetic models suggested diffusion controlled release. When evaluated against MDR strain of Mycobacterium tuberculosis, micelles showed improved antibacterial activity of drugs relative to corresponding free drug solutions. We further investigated the effects of block copolymers on the intestinal absorption of RIF and INH. Compared to free drugs, micelles showed improved drug permeability across Caco-2 monolayer. Our results suggest that polymer micelles are promising vehicles for delivering antitubercular drugs RIF and INH in a more effective manner.

Solubilization and interaction of cinnamic acid and its analogues with Pluronic® micelles

The interaction of cinnamic acid (CA) and its analogues viz. p-coumaric acid (PCA) and caffeic acid (CFA) with core-shell micelles of a moderately hydrophobic Pluronic® P123 has been investigated using cloud point (CP), viscosity, dynamic light scattering (DLS), small-angle neutron scattering (SANS) and steady-state fluorescence measurements. These solubilizates alter micellar behaviour of copolymer solution dependant on their hydrophobicity. P123 micelles exhibit time-dependent restructuring and responsive growth processes at different rates, depending on pH and in the presence of additives. Thus, restructuring and growth of P123 micelles can be easily tuned up to a substantial extent just by changing the concentration of the additives and the pH of the solution. Considering the medical applications of cinnamic acid and its analogues and considering use of Pluronics® in drug delivery systems, the present study can provide important insight of the possible time-dependant delivery mechanism of drugs.

The glucose‐responsive behavior of a block copolymer featuring boronic acid and glycine

ABSTRACTGlucose responsive block copolymer featuring boronic acid as a glucose responsive moiety and glycine are reported. The first block is polymerized through reversible addition–fragmentation chain transfer (RAFT) polymerization and the resulting poly(N‐acryloylmorpholine)113 (PAcM) is employed as a macro‐chain transfer agent for chain extension with pentafluorophenyl acrylate (PFPA) yielding a well‐defined PAcM113‐block‐poly(pentafluorophenyl acrylate)84 (PPFPA). The PPFPA block is then reacted with functional (3‐aminomethyl) phenyl boronic acid and glycine via post‐polymerization modification and the structure of the block copolymer is confirmed by proton nuclear magnetic resonance (NMR), 19F NMR, Fourier transform infrared, and gel permeation chromatography. By copolymerizing glycine into the polymer backbone, the relative pKa of the block copolymer is significantly lowered. The block copolymer can self‐assemble into core–shell micelles in aqueous solution and disassemble in response to glucose at the physiological pH. Furthermore, the encapsulation and release of Nile red (NR) as a hydrophobic model drug is studied under the physiological pH. The influence of the glucose concentration on the NR release from the polymeric micelles is demonstrated. These results suggested that the glucose‐responsive poly[(AcM)113‐b‐(3‐(aminomethyl)phenylboronic acid hydrochloride(‐co‐Gly)84] block copolymer has potential applications as a glucose‐responsive polymer for insulin delivery. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019, 57, 422–431

Cylindrical core-shell tween 80 micelle templated green synthesis of gold-silver hollow cubic nanostructures as efficient nanocatalysts

The non-ionic surfactant, Tween 80 (T80) a material with promising applications in the pharmaceutical, cosmetic, and food industries, has been explored here for the design of novel nanostructures (NS). We report here a direct one-pot seedless green method for the synthesis of gold-silver (AuAg) hollow cubic NS, with gold (90%) being the major component. The concentration of T80 plays an important role in determining the shape of the NS. A minimum T80 concentration of 50 mM is required for the formation of hollow cubic NS, whose sizes are controlled by increasing the T80 concentration. The unique molecular structure of T80 directs its molecules to assemble into core-shell cylindrical micelles that act as a soft-template for the growth of the NS. Study of the mechanism for the formation of the NS suggests nucleation followed by co-reduction of metal ions and its growth into hollow cubic NS over T80 micelles. The AuAg hollow cubic NS shows greater potential as efficient nanocatalysts than the non-cubic NS obtained at lower T80 concentrations. The hollowness and the cubic shape of the NS contribute towards their effective surface area that facilitates efficient catalytic activity. The AuAg NS may have biological applications due to their cell viabilities.

Effect of lipid chain length on nanostructured lipid carriers: Comprehensive structural evaluation by scattering techniques

The objective of the present investigation was to evaluate nano-dispersed systems of differently chained lipids (solid phases) using various scattering techniques. Nanostructured lipid carriers (NLCs) were fabricated by employing the microemulsification methodology in which dialkyldimethyl ammonium bromide (DxDAB) of different alkyl chain length (x = 12, 14, 16, 18) and oleic acid were used as the solid lipid and liquid lipid, respectively. For the first time, the effect of DxDAB as a function of the chain length of the double alkyl chain on the structural characteristics of NLCs was investigated. Dynamic light scattering (DLS) and static light scattering (SLS) results showed that a small but systematic size increase occurs with increase in the chain length ‘x’ of the DxDAB from 12 to 16, yet D18DAB based NLCs exhibited the smallest size irrespective of its higher hydrophobicity. Small angle neutron scattering (SANS) analysis revealed the structural make up of NLCs having spherical nanoparticles and triaxial ellipsoidal core-shell micelles in the system. In-vitro cytotoxicity evaluation indicated that toxicity is simply concentration-dependent phenomena and NLCs with less than 5 mg/mL are preferred for better in-vivo tolerance.

Natural Triterpenoid- and Oligo(Ethylene Glycol)-Pendant-Containing Block and Random Copolymers: Aggregation and pH-Controlled Release.

In this research, a series of random and block amphiphilic copolymers of norbornene derivatives containing biocompatible natural triterpenoid and oligo(ethylene glycol) pendants were synthesized by ring-opening metathesis polymerization. These copolymers were heat and pH responsive, and could self-assemble into core-shell spherical micelles in aqueous solution. Their hydrodynamic diameters corresponded to pH values and monomer sequences. By evaluating the loading and release capacity of hydrophobic molecules, it was found that 1) the higher the content of the hydrophobic triterpenoid, the higher the loading capacity; 2) the release speed could be trigged by the pH because of the deprotonation of the carboxyl groups on the triterpenoid. Additionally, the copolymers exhibited low cytotoxicity toward L929 cells, which makes them potential nanocarrier candidates for controlled drug delivery.

Hypoxia-responsive block copolymer radiosensitizers as anticancer drug nanocarriers for enhanced chemoradiotherapy of bulky solid tumors

Radiosensitizers play an important role in the clinical radiotherapy of hypoxic solid tumors to improve therapeutic efficacy. However, the in vivo performance of clinically used small-molecule radiosensitizers is commonly compromised by low bioavailability in hypoxic tumor regions. Herein, amphiphilic block copolymer radiosensitizers are prepared from clinically approved poly(ethylene glycol)-block-poly(l-glutamic acid) (PEG-b-PLG) and metronidazole (MN) to obtain MN-grafted PEG-b-PLG (PEG-b-P(LG-g-MN)) via condensation reaction, which can self-assemble into core-shell micelles as nanoparticle-formulated radiosensitizers in aqueous solution. The radiosensitizers are demonstrated to possess significantly higher sensitization enhancement ratio (SER) of 2.18 and potent in vivo tumor ablation capability upon exposure to electron beam irradiation compared with clinically used sodium glycididazole (GS) with SER of 1.32. Moreover, after optimizing the ratios of carboxyl and MN groups, PEG-b-P(LG-g-MN) micelles can be used to encapsulate doxorubicin (DOX@HMs) efficiently. Hypoxia-responsive structural transformation of MN into hydrophilic aminoimidazole triggers fast DOX release from DOX@HMs. After intravenous injection of DOX@HMs, potent ablation capability against bulky solid tumors (∼500 mm3) is realized at a low radiation dose (4 Gy) via enhanced chemoradiotherapy. Therefore, the developed novel amphiphilic block copolymer radiosensitizers can be concurrently used as high-efficiency radiosensitizers and hypoxia-responsive DOX nanocarriers for enhanced chemoradiotherapy.

In-vitro evaluation of cytotoxic and antioxidant properties of drugs solubilized in EO-PO star block copolymer micelles.

Self-assembly of a biocompatible, nontoxic, commercially available star shaped polyethylene oxide-polypropylene oxide block copolymer, Tetronics®1107 (mol. wt. = 15000, % ethylene oxide = 70, and HLB 18-23) in aqueous solution was examined using surface tension, fluorescence, viscosity, cloud point and dynamic light scattering. The copolymer being very hydrophilic shows poor surface activity and forms thermo-, pH and salt responsive nanosize core-shell micelles above critical micellization temperatures. These micelles showed markedly enhanced solubilization of hydrophobic drugs curcumin and quercetin. In vitro antioxidant activities (by free radical scavenging, reducing capacity and superoxide anion radical scavenging methods) and cytotoxicity (against CHO-K1 cell line) showed desirable properties in micellar drugs as compared to free one and similar cytotoxic effects were observed for free as well as micellar drugs. This suggests T1107 as promising tool for drug delivery.

Singlet Fission in Core–Shell Micelles of End-Functionalized Polymers

Singlet fission is the process in aggregates of molecular semiconductors where the initial product of light absorption (a singlet exciton) is converted into two correlated spin-triplet excitons. While most studies of singlet fission are conducted on assemblies of small molecule singlet fission chromophores, polymer self-assembly has yet to be explored as a means of creating nanostructures conducive for singlet fission. In this work, we use solution self-assembly of mono- and difunctionalized polymers to create core–shell micelles that display efficient singlet fission. The polymers are synthesized by copper(I)-catalyzed “click” chemistry between a 6,13-bis(triisopropylsilylethynyl)pentacene (TIPS-Pn) alkyne precursor and the corresponding azide-terminated poly(ethylene glycol) (PEG) polymer. Spontaneous solution self-assembly creates starlike and flowerlike core–shell micelles that are characterized by dynamic light scattering (DLS) and transmission electron microscopy (TEM) experiments. Ultrafast transie...

Vitamin A-decorated biocompatible micelles for chemogene therapy of liver fibrosis

Liver fibrosis refers to excessive accumulation of hepatic collagen, which is primarily produced by activated hepatic stellate cells (HSCs). No effective drugs are clinically available to treat this condition, reflecting the fact that antifibrotic drugs do not specifically target activated HSCs. Here, we report the synthesis and evaluation of poly (lactide-co-glycolide)-polyspermine-poly (ethylene glycol)-vitamin A (PLGA-PSPE-PEG-VA), and activated HSC-targeted, biocompatible amphiphilic polymers for co-delivery of chemical (silibinin) and genetic (siCol1α1) drugs that synergistically suppress collagen I accumulation in fibrogenesis. PLGA-PSPE-PEG-VA self-assembled into core-shell polymeric micelles (PVMs) at low concentrations. After loading with silibinin and siCol1α1, the resulting chemical/genetic drug-loaded PVMs (CGPVMs) exhibited a small particle size and a slightly positive surface. CGPVMs had very low cytotoxicity and hemolytic activity in vitro and were well tolerated in mice, with no liver toxicity or inflammation. Importantly, CGPVMs effectively accumulated in fibrotic livers and specifically targeted activated HSCs. As expected CGPVMs more efficiently decreased collagen I production and ameliorated liver fibrosis compared with chemical drug (silibinin)-loaded PVMs (CPVMs) or genetic drug (siCol1α1)-loaded PVMs (GPVMs) only. These results indicate that CGPVMs are a promising tool for targeted delivery of chemogenes to activated HSCs in the treatment of liver fibrosis.

Light-Controlled Simultaneous "On Demand" Release of Cytotoxic Combinations for Bimodal Killing of Cancer Cells.

In this contribution, we report a novel entirely photocontrolled nanoplatform comprising a binary mixture of pluronic copolymers capable of self-assembling into core-shell micelles and co-entrapping two photoactivatable components: a benzoporphyrin photosensitizer for photodynamic therapy (PDT) and coumarin-photocaged chemotherapeutic agent Chlorambucil (CAB). The resulting supramolecular micellar assembly is about 30 nm in diameter with a polydispersity index <0.1, stable for more than 72 h, and exhibits excellent preservation of the photochemical properties of the two photoresponsive components, even though they are confined within the same host nanocarrier. Appropriate regulation of the relative concentrations of these components makes them capable of absorbing visible light in comparable amounts, leading to effective simultaneous photogeneration of singlet oxygen and photo-triggered release of CAB. This "on demand" release of cytotoxic combinations results in amplified anticancer activity against MCF-7 human breast adenocarcinoma cells.

PH-Responsive Zwitterionic Copolymer DHA-PBLG-PCB for Targeted Drug Delivery: A Computer Simulation Study.

In this work, the self-assembled behaviors of zwitterionic copolymer docosahexaenoic acid- b-poly(γ-benzyl-l-glutamate)- b-poly(carboxybetaine methacrylate) (DHA-PBLG-PCB) and the loading and release mechanism of the anticancer drug doxorubicin (DOX) was investigated via computer simulations. The effects of polymer concentration, drug content, and pH on polymeric micelles were explored by dissipative particle dynamics (DPD) simulations. Simulation results show that DHA-PBLG15-PCB10 can self-assemble into core-shell micelles; in addition, the drug-loaded micelles have a pH-responsive feature. DOX can be encapsulated into the core-shell micelle under normal physiological pH conditions, whereas it can be released under acidic pH conditions. The self-assembled behaviors of copolymer DHA-PBLG-PEG were also studied to have a comparison with those of DHA-PBLG-PCB. The DHA-PBLG15-PCB10 system has a stable structure and it has a great potential to serve as drug delivery vehicles for targeted drug delivery.

Phase behaviour, micellar structure and linear rheology of tetrablock copolymer Tetronic 908

Tetronics are X-shaped block-copolymers of polyethylene oxide and polypropylene oxide, which self-assemble into micelles and can undergo a sol-gel transition; these transitions are dependent on temperature, concentration but also pH, due to the central diamine group of the tetrablock. We report the nanoscale morphologies underlying these different phases and the rheology of the systems for a very large, highly hydrophilic block copolymer, Tetronic 908, through the combined use of oscillatory rheology, steadyblock-state and time-resolved fluorescence, small-angle neutron scattering (SANS), dynamic light scattering (DLS) and Fourier transform infrared attenuated total reflectance (FTIR-ATR). At low concentrations, SANS reveal core-shell micelles of ca. 10 nm radius, presenting a dehydrated core and a highly hydrated shell, with relatively small aggregation numbers (Nagg ≈ 13). The micelles are notably affected by the pH, due to the protonation of the central amine spacer at low pH (pH ≈ 2), which shifts micellization to higher temperature, with smaller micelles than at natural pH. In the intermediate concentration regime (10–15%), micelles become smaller (Nagg ≈ 5), and present a higher hydration of the core. In the high concentration regime, Tetronic 908 undergoes a sol-gel transition above a threshold temperature, which is fully inhibited at acidic pH. SANS data from the gel phase reveal a BCC order of tightly packed spheres. Temperature sweeps in oscillatory rheology show a shift of the onset of gelation towards lower temperatures as concentration increases, an increase in the elastic modulus G′ and an expansion of gel region over a larger range of temperatures. SANS and rheology reveal that at pH below the natural pH (ca. 8), gelation is shifted to higher temperatures, but the morphology of the gels is similar, while under highly acidic conditions the gelation is fully suppresed.

Highly catalytic activity of nickel nanoparticles generated in poly(methylmethacrylate)@poly(2-hydroxyethylmethacrylate) (PMMA@PHEMA) core–shell micelles for the reduction of 4-nitrophenol (4-NP)

Excellent catalytic reduction of 4-NP in aqueous solution was achieved under ambient condition using nickel (Ni) nanoparticles generated in PMMA@PHEMA polymeric micelles. Ni nanoparticles were formed in two different PMMA@PHEMA micelles, namely Ni-loaded PMMA10K@PHEMA5K and Ni-loaded PMMA12K@PHEMA34K which resulted in the distinctive differences in Ni content as well as the sizes of Ni nanoparticles. Besides the concentration of the catalyst, the reduction rate of 4-NP depended on PMMA@PHEMA micelle structure, i.e., higher catalytic activity was observed for Ni-loaded PMMA10K@PHEMA5K. More importantly, the catalytic performance of Ni-loaded PMMA12K@PHEMA34K was markedly improved with increasing amount of PHEMA-shell crosslinker despite a reduction of Ni content in the micelles.

Facially amphiphilic polyionene biocidal polymers derived from lithocholic acid

Bacterial infections have become a global issue that requires urgent attention, particularly regarding to emergence of multidrug resistant bacteria. We developed quaternary amine-containing antimicrobial poly(bile acid)s that contain a hydrophobic core of lithocholic acid in the main-chain. Interestingly, by choosing appropriate monomers, these cationic polymers can form core-shell micelles. These polymers exhibited biocidal activity against both Gram-positive and Gram-negative bacterial species. It is demonstrated that the micelles can deliver hydrophobic antibiotics that functionally have dual antimicrobial activities. Cytotoxicity assays against HeLa cells showed dosage-dependent toxicity for polymers with longer linkers.