In vitro evaluation of pH-sensitive cholesterol-containing stable polymeric micelles for delivery of camptothecin

Glutathione-Responsive Tannic Acid-Assisted FRET Nanomedicine for Cancer Therapy

In cancer combination therapy, a multimodal delivery vector is used to improve the bioavailability of multiple anti-cancer hydrophobic drugs. Further, targeted delivery of therapeutics along with simultaneous monitoring of the drug release at the tumor site without normal organ toxicity is an emerging and effective strategy for cancer treatment. However, the lack of a smart nano-delivery system limits the application of this therapeutic strategy. To overcome this issue, a PEGylated dual drug, conjugated amphiphilic polymer (CPT-S-S-PEG-CUR), has been successfully synthesized by conjugating two hydrophobic fluorescent anti-cancer drugs, curcumin (CUR) and camptothecin (CPT), through an ester and a redox-sensitive disulfide (-S-S-) linkage, respectively, with a PEG chain via in situ two-step reactions. CPT-S-S-PEG-CUR is spontaneously self-assembled in the presence of tannic acid (TA, a physical crosslinker) into anionic, comparatively smaller-sized (~100 nm), stable nano-assemblies in water in comparison to only polymer due to stronger H-bond formation between polymer and TA. Further, due to the spectral overlap between CPT and CUR and a stable, smaller nano-assembly formation by the pro-drug polymer in water in presence of TA, a successful Fluorescence Resonance Energy Transfer (FRET) signal was generated between the conjugated CPT (FRET donor) and conjugated CUR (FRET acceptor). Interestingly, these stable nano-assemblies showed a preferential breakdown and release of CPT in a tumor-relevant redox environment (in the presence of 50 mM glutathione), leading to the disappearance of the FRET signal. These nano-assemblies exhibited a successful cellular uptake by the cancer cells and an enhanced antiproliferative effect in comparison to the individual drugs in cancer cells (AsPC1 and SW480). Such promising in vitro results with a novel redox-responsive, dual-drug conjugated, FRET pair-based nanosized multimodal delivery vector can be highly useful as an advanced theranostic system towards effective cancer treatment.

Pneumolysin/Plasma Protein Adsorption, Bacterial Adherence, and Cell Adhesion Characteristics of a Cell-Membrane-Mimicking Polymer System

This study delivers the first report on a cell-membrane-mimicking polymer system, poly[oxy(4-(13-cholenoatenonyl)-1,2,3-triazoyl-1-methyl)ethylene-random-oxy(4-(13-phosphorylcholinenonyl)-1,2,3-triazoyl-1-methyl)ethylene] (PGA-Chol_mPC_n) films in various compositions in terms of physicochemical properties, protein adsorptions, bacterial adherences, and human cell adhesions. Higher Chol-containing PGA-Chol_mPC_n in a self-assembled multi-bilayer membrane structure is confirmed to show excellently high affinity to pneumolysin (a cytolysin) and its C-terminal fragment (domain 4) but substantially suppressed affinity to the N-terminal fragment (domains 1-3) and further to plasma proteins. Furthermore, the adherences of pathogenic bacteria are increased favorably; however, the adhesion and proliferation of a human HEp-2 cell line are hindered severely. In contrast, higher-PC-containing PGA-Chol_mPC_n membranes promote HEp-2 cell adhesion and proliferation but significantly suppress the adsorptions of pneumolysin and its fragments and plasma proteins as well as bacterial adherence. The results collectively confirm that PGA-Chol_mPC_n can yield a membrane platform enriched with hydrophobic Chol and hydrophilic and zwitterionic PC moieties in any desired compositions, providing highly selective and sensitive physicochemical characters and biocompatibilities which are demanded for applications in various fields including biomedicine, cosmetics, and environmentally friendly consumer products.

Limited Impact of the Protein Corona on the Cellular Uptake of PEGylated Zein Micelles by Melanoma Cancer Cells

The formation of a protein layer “corona” on the nanoparticle surface upon entry into a biological environment was shown to strongly influence the interactions with cells, especially affecting the uptake of nanomedicines. In this work, we present the impact of the protein corona on the uptake of PEGylated zein micelles by cancer cells, macrophages, and dendritic cells. Zein was successfully conjugated with poly(ethylene glycol) (PEG) of varying chain lengths (5K and 10K) and assembled into micelles. Our results demonstrate that PEGylation conferred stealth effects to the zein micelles. The presence of human plasma did not impact the uptake levels of the micelles by melanoma cancer cells, regardless of the PEG chain length used. In contrast, it decreased the uptake by macrophages and dendritic cells. These results therefore make PEGylated zein micelles promising as potential drug delivery systems for cancer therapy.

Ag NCs as a potent antibiofilm agent against pathogenic Pseudomonas aeruginosa and Acinetobacter baumannii and drug-resistant Bacillus subtilis by affecting chemotaxis and flagellar assembly pathway genes

Ag NCs can mediate biofilm degradation through the regulation of bacterial chemotaxis and flagellar assembly pathway genes.

Emergence of cationic polyamine dendrimersomes: design, stimuli sensitivity and potential biomedical applications

For decades, self-assembled lipid vesicles have been widely used in clinics as nanoscale delivery systems for various biomedical applications, including treatment of various diseases. Due to their core-shell architecture and versatile nature, they have been successfully used as carriers for the delivery of a wide range of therapeutic cargos, including drugs and nucleic acids, in cancer treatment. Recently, surface-modified polyamine dendrimer-based vesicles, or dendrimersomes, have emerged as promising alternatives to lipid vesicles for various biomedical applications, due to their ease of synthesis, non-immunogenicity, stability in circulation and lower size polydispersity. This mini-review provides an overview of the recent advances resulting from the use of biomimetic hydrophobically-modified polyamine-based dendrimersomes towards biomedical applications, focusing mainly on the two most widely used polyamine dendrimers, namely polyamidoamine (PAMAM) and poly(propylene imine) (PPI) dendrimers.

Interplay of distributions of multiple guest molecules in block copolymer micelles: A dissipative particle dynamics study

HYPOTHESIS

Delivery of multiple payloads using the same micelle is of significance to achieve multifunctional or synergistic effects. The interacting distribution of different payloads in micelles is expected to influence the loading stability and capacity. It is highly desirable to explore how intermolecular interactions affect the joint distribution of multi-payloads.

EXPERIMENTS

Dissipative Particle Dynamics simulations were performed to probe the loading of three payloads: decane with a linear carbon chain, butylbenzene with an aromatic ring connected to carbon chain, and naphthalene with double aromatic rings, within poly(β-amino ester)-b-poly(ethylene glycol) micelles. Properties of core-shell micelles, e.g., morphological evolution, radial density distribution, mean square displacement, and contact statistics, were analyzed to reveal payloads loading stability and capacity. Explorations were extended to vesicular, multi-compartment, double helix, and layer-by-layer micelles with more complex inner structures.

FINDINGS

Different payloads have their own preferred locations. Decane locates at the hydrophilic/hydrophobic interface, butylbenzene occupies both the hydrophilic/hydrophobic interface and the hydrophobic core, while naphthalene enters the hydrophobic core. More efficient delivery of multi-payloads is achieved since the competition of payloads occupying preferred locations is minimized. The fusion of micelles encapsulating different payloads suggests that specific payloads will move to their preferred positions without interfering other payloads.

3D printed systems for colon-specific delivery of camptothecin-loaded chitosan micelles

The use of 3D printing technology in the manufacturing of drug delivery systems has expanded and benefit of a customized care. The ability to create tailor-made structures filled with drugs/delivery systems with suitable drug dosage is especially appealing in the field of nanomedicine. In this work, chitosan-based polymeric micelles loaded with camptothecin (CPT) were incorporated into 3D printing systems (printfills) sealed with an enteric layer, aiming to protect the nanosystems from the harsh environment of the gastrointestinal tract (GIT). Polymeric micelles and printfills were fully characterized and, a simulated digestion of the 3D systems upon an oral administration was performed. The printfills maintained intact at the simulated gastric pH of the stomach and, only released the micelles at the colonic pH. From there, the dissolution media was used to recreate the intestinal absorption and, chitosan micelles showed a significant increase of the CPT permeability compared to the free drug, reaching an apparent permeability coefficient (P_app) of around 9×10^-6 cm/s in a 3D intestinal cell-based model. The combination of 3D printing with nanotechnology appears to have great potential for the colon-specific release of polymeric micelles, thereby increasing intestinal absorption while protecting the system/drug from degradation throughout the GIT.

Octadecyl chain-bearing PEGylated poly(propyleneimine)-based dendrimersomes: physicochemical studies, redox-responsiveness, DNA condensation, cytotoxicity and gene delivery to cancer cells

Stimuli-responsive nanocarriers have become increasingly important for nucleic acid and drug delivery in cancer therapy. Here, we report the synthesis, characterization and evaluation of disulphide-linked, octadecyl (C18 alkyl) chain-bearing PEGylated generation 3-diaminobutyric polypropylenimine dendrimer-based vesicles (or dendrimersomes) for gene delivery. The lipid-bearing PEGylated dendrimer was successfully synthesized through in situ two-step reaction. It was able to spontaneously self-assemble into stable, cationic, nanosized vesicles, with low critical aggregation concentration value, and also showed redox-responsiveness in presence of a glutathione concentration similar to that of the cytosolic reducing environment. In addition, it was able to condense more than 70% of DNA at dendrimer: DNA weight ratios of 5 : 1 and higher. This dendriplex resulted in an enhanced cellular uptake of DNA at dendrimer: DNA weight ratios of 10 : 1 and 20 : 1, by up to 16-fold and by up to 28-fold compared with naked DNA in PC-3 and DU145 prostate cancer cell lines respectively. At a dendrimer: DNA weight ratio of 20 : 1, it led to an increase in gene expression in PC-3 and DU145 cells, compared with DAB dendriplex. These octadecyl chain-bearing, PEGylated dendrimer-based vesicles are therefore promising redox-sensitive drug and gene delivery systems for potential applications in combination cancer therapy.

Combination therapy of biogenic C-dots and lysozyme for enhanced antibacterial and antibiofilm activity

Nearly 80% of human chronic infections are caused due to bacterial biofilm formation. The increased resistance against the conventional antimicrobial agents makes it difficult to treat the biofilm-related infections. The antibiotics resistance developed by planktonic cells has also become a major threat for human. Therefore, we have attempted here to develop an effective alternative strategy to overcome the issues of antibiotics resistance of bacteria. Upon synthesis, biogenic C-dots were combined with lysozymes which were further encapsulated into chitosan nanocarrier to form C-dots carrier (CDC). The as-synthesized C-dots were found irregular shaped and the average size of C-dots and CDC were 8 ± 2 nm and 450 ± 50 nm, respectively. To ensure secure and targeted delivery of C-dots and lysozyme we have employed chitosan, a biodegradable and natural biopolymer, as a delivery system. The study of time-dependent bacterial growth and flow cytometry analysis demonstrated that CDC can exhibit a synergistic bactericidal activity against the antibiotics resistant recombinant E. coli cells. Further, we have shown that the CDC could be a potent agent for both prevention of biofilm formation and eradication of preformed biofilm. In addition, we have observed that our drug delivery system is hemocompatible in nature making it suitable for in vivo applications. Therefore, we believe that the combination therapy of C-dots and lysozyme may be used as an excellent antibacterial and antibiofilm strategy.

Polymeric Drug Delivery Systems Bearing Cholesterol Moieties: A Review

This review aims to provide an overview of polymers comprising cholesterol moiety/ies designed to be used in drug delivery. Over the last two decades, there have been many papers published in this field, which are summarized in this review. The primary focus of this article is on the methods of synthesis of polymers bearing cholesterol in the main chain or as side chains. The data related to the composition, molecular weight, and molecular weight distribution of polymers are presented. Moreover, other aspects, such as forms of carriers, types of encapsulated drugs, encapsulation efficiency and capacity, are also included.

The Efficacy of Cholesterol-Based Carriers in Drug Delivery

Several researchers have reported the use of cholesterol-based carriers in drug delivery. The presence of cholesterol in cell membranes and its wide distribution in the body has led to it being used in preparing carriers for the delivery of a variety of therapeutic agents such as anticancer, antimalarials and antivirals. These cholesterol-based carriers were designed as micelles, nanoparticles, copolymers, liposomes, etc. and their routes of administration include oral, intravenous and transdermal. The biocompatibility, good bioavailability and biological activity of cholesterol-based carriers make them potent prodrugs. Several in vitro and in vivo studies revealed cholesterol-based carriers potentials in delivering bioactive agents. In this manuscript, a critical review of the efficacy of cholesterol-based carriers is reported.

Camptothecin-based dendrimersomes for gene delivery and redox-responsive drug delivery to cancer cells

Combination therapy involving chemotherapeutic drugs and genes is emerging as a promising strategy to provide a synergistic therapeutic effect, to overcome drug resistance while reducing the severe side effects associated with conventional chemotherapeutic drugs. However, the lack of nanomedicines able to simultaneously carry anti-cancer drugs and nucleic acids limits the application of this therapeutic strategy. To overcome this issue, we proposed to synthesize a pro-drug dendrimer by conjugating the PEGylated, positively charged generation 3-diaminobutyric polypropylenimine dendrimer to the anti-cancer drug camptothecin with a redox-sensitive disulphide linkage, and evaluate its efficacy to co-deliver the complexed DNA and camptothecin to cancer cells. This PEGylated pro-drug dendrimer was found to spontaneously self-assemble into cationic (∼3-5 mV) vesicles at pH 7.4, at a critical aggregation concentration of about 200 μg mL-1. These vesicles (dendrimersomes) became smaller (150-200 nm) with increasing dendrimer concentration and remained stable over 7 days. They were able to release about 70% of the conjugated camptothecin in presence of 50 mM glutathione (equivalent to the intracellular environment of tumor tissue). They could also condense more than 85% of the DNA at dendrimer : DNA weight ratios of 5 : 1 and higher. DNA condensation occurred instantly and was found to be stable for at least 24 h. This led to an enhanced cellular uptake of DNA (by up to 1.6-fold) and increased gene transfection (by up to 2.4-fold) in prostate cancer cells in comparison with the unmodified dendrimer. These novel dendrimersomes are therefore promising for single carrier-based combination cancer therapy.

Vinblastine-Loaded Nanoparticles with Enhanced Tumor-Targeting Efficiency and Decreasing Toxicity: Developed by One-Step Molecular Imprinting Process

Molecularly imprinted polymers have exhibited good performance as carriers on drug loading and sustained release. In this paper, vinblastine (VBL)-loaded polymeric nanoparticles (VBL-NPs) were prepared by a one-step molecular imprinting process, avoiding the waste and incomplete removal of the template, and evaluated as targeting carriers for VBL delivery after modification. Using acryloyl amino acid comonomers and disulfide cross-linkers, VBL-NPs were synthesized and then conjugated with poly(ethylene glycol)-folate. The dynamic size of the obtained VBL-NPs-PEG-FA was 258.3 nm (PDI = 0.250), and the encapsulation efficiency was 45.82 ± 1.45%. The nanoparticles of VBL-NPs-PEG-FA were able to completely release VBL during 48 h under a mimic tumor intracellular condition (pH 4.5, 10 mM glutathione (GSH)), displaying significant redox responsiveness, whereas the release rates were much slower in the mimic body liquid (pH 7.4, 2 μM GSH) and tumor extracellular environment (pH 6.5, 2 μM GSH). Furthermore, the carriers NPs-PEG-FA, prepared without VBL, showed satisfactory intrinsic hemocompatibility, cellular compatibility, and tumor-targeting properties: they could rapidly and efficiently accumulate to folate receptor positive Hela cells and then internalized via receptor-mediated endocytosis, and the retention in tumor tissues could last for over 48 h. Interestingly, VBL-NPs-PEG-FA could evidently increase the accumulation of VBL in tumor tissues while decreasing the distribution of VBL in organs, exert similar anticancer efficacy against Hela tumors in the xenograft model of nude mice to VBL injection, and significantly improve the abnormality of liver and spleen observed in VBL injection. VBL-NPs-PEG-FA has the potential to be the delivery carrier for VBL by enhancing the tumor-targeting efficacy of VBL and decreasing toxicity to normal tissues.

Nano-engineered delivery systems for cancer imaging and therapy: Recent advances, future direction and patent evaluation

Cancer is the second highest cause of death worldwide. Several therapeutic approaches, such as conventional chemotherapy, antibodies and small molecule inhibitors and nanotherapeutics have been employed in battling cancer. Amongst them, nanotheranostics is an example of successful personalized medicine bearing dual role of early diagnosis and therapy to cancer patients. In this review, we have focused on various types of theranostic polymer and metal nanoparticles for their role in cancer therapy and imaging concerning their limitation, future application such as dendritic cell cancer vaccination, gene delivery, T-cell activation and immune modulation. Also, some of the recorded patent applications and clinical trials have been illustrated. The impact of the biological microenvironment on the biodistribution and accumulation of nanoparticles have been discussed.

Redox-sensitive, cholesterol-bearing PEGylated poly(propylene imine)-based dendrimersomes for drug and gene delivery to cancer cells

Stimuli-responsive nanocarriers have attracted increased attention as materials that can facilitate drug and gene delivery in cancer therapy. The present study reports the development of redox-sensitive dendrimersomes comprising disulfide-linked cholesterol-bearing PEGylated dendrimers, which can be used as drug and gene delivery systems. Two disulfide-linked cholesterol-bearing PEGylated generation 3 diaminobutyric polypropylenimine dendrimers have been successfully synthesized via an in situ two-step reaction. They were able to spontaneously self-assemble into stable, cationic, nanosized vesicles (or dendrimersomes) with lower critical aggregation concentration values for high-cholesterol-bearing vesicles. These dendrimersomes were able to entrap both hydrophilic and hydrophobic dyes, and they also showed a redox-responsive sustained release of the entrapped guests in the presence of a glutathione concentration similar to that of a cytosolic reducing environment. The high-cholesterol-bearing dendrimersomes were found to have a higher melting enthalpy, increased adsorption tendency on mica surface, entrapping ability for a larger amount of hydrophobic drugs, and increased resistance to redox-responsive environments in comparison with their low-cholesterol counterpart. In addition, both dendrimersomes were able to condense more than 85% of the DNA at all the tested ratios for the low-cholesterol vesicles, and at dendrimer : DNA weight ratios of 1 : 1 and higher for the high-cholesterol vesicles. These vesicles resulted in an enhanced cellular uptake of DNA, by up to 15-fold when compared with naked DNA with low-cholesterol vesicles. As a result, they increased the gene transfection on the PC-3 prostate cancer cell line, with the highest transfection being obtained with low-cholesterol vesicle complexes at a dendrimer : DNA weight ratio of 5 : 1 and high-cholesterol vesicle complexes at a dendrimer : DNA weight ratio of 10 : 1. These transfection levels were about 5-fold higher than those observed when treated with naked DNA. These cholesterol-bearing PEGylated dendrimer-based vesicles are, therefore, promising as redox-sensitive drugs and gene delivery systems for potential applications in combination cancer therapies.

Polymeric Micelles Based on Modified Glycol Chitosan for Paclitaxel Delivery: Preparation, Characterization and Evaluation

Amphiphilic polymer of α-tocopherol succinate modified glycol chitosan (TS-GC) was successfully constructed by conjugating α-tocopherol succinate to the skeleton of glycol chitosan and characterized by Fourier-transform infrared (FT-IR) and proton nuclear magnetic resonance (¹H-NMR). In aqueous milieu, the conjugates self-assembled to micelles with the critical aggregation concentration of 7.2 × 10⁻³ mg/mL. Transmission electron microscope (TEM) observation and dynamic light scattering (DLS) measurements were carried out to determine the physicochemical properties of the micelles. The results revealed that paclitaxel (PTX)-loaded TS-GC micelles were spherical in shape. Moreover, the PTX-loaded micelles showed increased particle sizes (35 nm vs. 142 nm) and a little reduced zeta potential (+19 mV vs. +16 mV) compared with blank micelles. The X-ray diffraction (XRD) spectra demonstrated that PTX existed inside the micelles in amorphous or molecular state. In vitro and in vivo tests showed that the PTX-loaded TS-GC micelles had advantages over the Cremophor EL-based formulation in terms of low toxicity level and increased dose, which suggested the potential of the polymer as carriers for PTX to improve their delivery properties.

pH-sensitive micelles self-assembled from polymer brush (PAE-g-cholesterol)-b-PEG-b-(PAE-g-cholesterol) for anticancer drug delivery and controlled release

A novel amphiphilic pH-sensitive triblock polymer brush (poly(β-amino esters)-g-cholesterol)-b-poly(ethylene glycol)-b-(poly(β-amino esters)-g-cholesterol) ((PAE-g-Chol)-b-PEG-b-(PAE-g-Chol)) was designed and synthesized successfully through a three-step reaction, and their self-assembled polymeric micelles were used as hydrophobic anticancer drug delivery carriers to realize effectively controlled release. The critical micelle concentrations were 6.8 μg/mL, 12.6 μg/mL, 17.4 μg/mL, and 26.6 μg/mL at pH values of 7.4, 6.5, 6.0, and 5.0, respectively. The trend of critical micelle concentrations indicated that the polymer had high stability that could prolong the circulation time in the body. The hydrodynamic diameter and zeta potential of the polymeric micelles were influenced significantly by the pH values. As pH decreased from 7.4 to 5.0, the particle size and zeta potential increased from 205.4 nm to 285.7 nm and from +12.7 mV to +47.0 mV, respectively. The pK_b of the polymer was confirmed to be approximately 6.5 by the acid–base titration method. The results showed that the polymer had sharp pH-sensitivity because of the protonation of the amino groups, resulting in transformation of the PAE segment from hydrophobic to hydrophilic. Doxorubicin-loaded polymeric micelles were prepared with a high loading content (20%) and entrapment efficiency (60%) using the dialysis method. The in vitro results demonstrated that drug release rate and cumulative release were obviously dependent on pH values. Furthermore, the drug release mechanism was also controlled by the pH values. The polymer had barely any cytotoxicity, whereas the doxorubicin-loaded system showed high toxicity for HepG2 cells as free drugs. All the results proved that the pH-sensitive triblock polymer brush and its self-assembled micelle might be a potential delivery carrier for anticancer drugs with sustained release.

In Vitro Drug and Gene Delivery Using Random Cationic Copolymers Forming Stable and pH-Sensitive Polymersomes

Stimuli-sensitive polymeric vesicles or polymersomes as self-assembled colloidal nanocarriers have received paramount importance for their integral role as delivery system for therapeutics and biotherapeutics. This work describes spontaneous polymersome formation at pH 7, as evidenced by surface tension, steady state fluorescence, dynamic light scattering, and microscopic studies, by three hydrophilic random cationic copolymers synthesized using N,N-(dimethylamino)ethyl methacrylate (DMAEM) and methoxy poly(ethylene glycol) monomethacrylate in different mole ratios. The results suggest that methoxy poly(ethylene glycol) chains constitute the bilayer membrane of the polymersomes and DMAEM projects toward water constituting the positively charged surface. The polymersomes have been observed to release their encapsulated guest at acidic pH as a result of transformation into polymeric micelles. All these highly biocompatible cationic polymers show successful gene transfection ability as nonviral vector on human cell line with different potential. Thus these polymers prove their utility as a potential delivery system for hydrophilic model drug as well as genetic material.

Antiproliferative Activity and Cellular Uptake of Evodiamine and Rutaecarpine Based on 3D Tumor Models

Evodiamine (EVO) and rutaecarpine (RUT) are promising anti-tumor drug candidates. The evaluation of the anti-proliferative activity and cellular uptake of EVO and RUT in 3D multicellular spheroids of cancer cells would better recapitulate the native situation and thus better reflect an in vivo response to the treatment. Herein, we employed the 3D culture of MCF-7 and SMMC-7721 cells based on hanging drop method and evaluated the anti-proliferative activity and cellular uptake of EVO and RUT in 3D multicellular spheroids, and compared the results with those obtained from 2D monolayers. The drugs’ IC₅₀ values were significantly increased from the range of 6.4–44.1 μM in 2D monolayers to 21.8–138.0 μM in 3D multicellular spheroids, which may be due to enhanced mass barrier and reduced drug penetration in 3D models. The fluorescence of EVO and RUT was measured via fluorescence spectroscopy and the cellular uptake of both drugs was characterized in 2D tumor models. The results showed that the cellular uptake concentrations of RUT increased with increasing drug concentrations. However, the EVO concentrations uptaken by the cells showed only a small change with increasing drug concentrations, which may be due to the different solubility of EVO and Rut in solvents. Overall, this study provided a new vision of the anti-tumor activity of EVO and RUT via 3D multicellular spheroids and cellular uptake through the fluorescence of compounds.

Cholesterol-Enhanced Polylactide-Based Stereocomplex Micelle for Effective Delivery of Doxorubicin

Nanoscale micelles as an effective drug delivery system have attracted increasing interest in malignancy therapy. The present study reported the construction of the cholesterol-enhanced doxorubicin (DOX)-loaded poly(D-lactide)-based micelle (CDM/DOX), poly(L-lactide)-based micelle (CLM/DOX), and stereocomplex micelle (CSCM/DOX) from the equimolar enantiomeric 4-armed poly(ethylene glycol)-polylactide copolymers in aqueous condition. Compared with CDM/DOX and CLM/DOX, CSCM/DOX showed the smallest hydrodynamic size of 96 ± 4.8 nm and the slowest DOX release. The DOX-loaded micelles exhibited a weaker DOX fluorescence inside mouse renal carcinoma cells (i.e., RenCa cells) compared to free DOX·HCl, probably because of a slower DOX release. More importantly, all the DOX-loaded micelles, especially CSCM/DOX, exhibited the excellent antiproliferative efficacy that was equal to or even better than free DOX·HCl toward RenCa cells attributed to their successful internalization. Furthermore, all of the DOX-loaded micelles exhibited the satisfactory hemocompatibility compared to free DOX·HCl, indicating the great potential for systemic chemotherapy through intravenous injection.

PEG based random copolymer micelles as drug carriers: the effect of hydrophobe content on drug solubilization and cytotoxicity

The effect of hydrophobe content on PEG based random polymeric micelles as drug carriers: a comparative study.

pH-induced vesicle-to-micelle transition in amphiphilic diblock copolymer: investigation by energy transfer between in situ formed polymer embedded gold nanoparticles and fluorescent dye

The ability to regulate the formation of nanostructures through self-assembly of amphiphilic block copolymers is of immense significance in the field of biology and medicine. In this work, a new block copolymer synthesized by using reversible addition-fragmentation chain transfer (RAFT) polymerization technique from poly(ethylene glycol) monomethyl ether acrylate (PEGMA) and Boc-l-tryptophan acryloyloxyethyl ester (Boc-l-trp-HEA) was found to spontaneously form pH-responsive water-soluble nanostructures after removal of the Boc group. While polymer vesicles or polymerosomes were formed at physiological pH, the micelles were formed at acidic pH (< 5.2), and this facilitated a pH-induced reversible vesicle-to-micelle transition. Formation of these nanostructures was confirmed by different characterization techniques, viz. transmission electron microscopy, dynamic light scattering, and steady-state fluorescence measurements. Further, these vesicles were successfully utilized to reduce HAuCl4 and stabilize the resulting gold nanoparticles (AuNPs). These AuNPs, confined within the hydrophobic shell of the vesicles, could participate in energy transfer process with fluorescent dye molecules encapsulated in the core of the vesicles, thus forming a nanometal surface energy transfer (NSET) pair. Subsequently, following the efficiency of energy transfer between this pair, it was possible to monitor the process of transition from vesicles to micelles. Thus, in this work, we have successfully demonstrated that NSET can be used to follow the transition between nanostructures formed by amphiphilic block copolymers.

pH-sensitive amphiphilic copolymer brush Chol-g-P(HEMA-co-DEAEMA)-b-PPEGMA: synthesis and self-assembled micelles for controlled anti-cancer drug release

A novel pH-sensitive amphiphilic copolymer Chol-g-P(HEMA-co-DEAEMA)-b-PPEGMA and its micelles were developed as a promising anti-cancer drug carrier.