Search

Amphiphilic block copolymers are common materials used for the fabrication of various nanostructures with biomedical applications including nanocapsules, nanospheres, micelles and polymeric vesicles. According to the literature, polymersomes have several advantages compared to other nanostructures used as drug delivery systems comprising better stability, facile synthesis, prolonged circulation time, and passive/active targeting capability. Various types of nanoparticles are formed by varying the ratio of the hydrophobic/hydrophilic blocks. Changing hydrophobic/hydrophilic ratio of amphiphilic block copolymers has an impact on the structural characteristics of polymers such as changing molecular weight and surface functionalization of the block copolymer. Thus, polymerization strategies are an important factor that influences polymersomes quality. In this review, different polymerization strategies for the synthesis of block copolymers applied in polymersomes formation, are described.

Antibody-drug conjugates (ADCs) are among the most significant advances in clinical cancer treatments, however, they are haunted with fundamental issues like low drug/antibody ratio (DAR), need of large amount of antibody, and complex chemistry. Targeted nanomedicines while offering a promising alternative to ADCs are afflicted with drug leakage and inferior cancer-specificity. Herein, we developed an intelligent cell-selective nanotoxin based on anti-CD44 antibody-polymersome-DM1 conjugates (aCD44-AP-DM1) for potent treatment of solid tumors. DM1 was simultaneously coupled to vesicular membrane via disulfide bonds during self-assembly and anti-CD44 antibody was facilely clicked onto polymersome surface, tailor-making an optimal aCD44-AP-DM1 with a controlled antibody density of 5.0, extraordinary DAR of 275, zero drug leakage and rapid reduction-responsive DM1 release. aCD44-AP-DM1 displayed a high specificity and exceptional cytotoxicity toward MDA-MB-231 triple negative breast cancer, SMMC-7721 hepatocellular carcinoma and A549 non-small cell lung cancer cells with half-maximal inhibitory concentrations (IC50) of 21.4, 3.7 and 64.6 ng/mL, respectively, 3.6–47.2-fold exceeding non-targeted P-DM1. Intriguingly, the systemic administration of aCD44-AP-DM1 significantly suppressed subcutaneous MDA-MB-231 tumor xenografts in nude mice while intratumoral injection achieved complete tumor eradication in four out of five mice, without causing toxicity. This intelligent cell-selective nanotoxin has emerged as a better platform over ADCs for targeted cancer therapy.

Nano drug delivery systems have attracted researchers' growing attention and are gradually emerging into the public views. More and more nano-formulations are being approved for marketing or clinical use, representing the field's booming development. Copolymer self-assembly systems such as micelles, nanoparticles, polymersomes occupy a prominent position in the field of nano-drug delivery carriers. Among them, polymersomes, unlike micelles or nanoparticles, resemble liposomes' structure and possess large internal hollow hydrophilic reservoirs, allowing them to carry hydrophilic drugs. Nevertheless, their insufficient drug loading efficiency and unruly self-assembly morphology have somewhat constrained their applications. Especially for the delivery of biomacromolecule such as peptides, the encapsulation efficiency is always considered to be a formidable obstacle, even if the enormous hydrophilic core would render the polymersomes to have considerable potential in this regard. Reassuringly, the emergence of asymmetric polymersomes holds the prospect of solving this problem. With the development of synthetic technology and a deeper understanding of the self-assembly process, the asymmetric polymersomes which are with different inner and outer shell composition have been gradually recognized by researchers. It has made possible elevated drug loading, more controllable assembly processes and release performance. The internal hydrophilic blocks different from the outer shell could be engineered to have a more remarkable affinity to the cargos or could contain a non-watery aqueous phase to enable the thermodynamically preferred encapsulation of cargos, which would allow for a substantial improvement in drug encapsulation efficiency compared to the conventional approach. In this paper, we aim to deepen the understanding to asymmetric polymersomes and lay the foundation for the development of this field by describing four main elements: the mechanism of their preparation and asymmetric membrane formation process, the characterization of asymmetric membranes, the efficient drug loading, and the special stimulus-responsive release mechanism.

Embargado hasta 09/04/2023 Polymersomes and related self-assembled nanostructures displaying Aggregation-Induced Emission (AIE) are highly relevant for plenty of applications in imaging, biology and functional devices. Experimentally simple, scalable and universal strategies for on-demand self-assembly of polymers rendering well-defined nanostructures are highly desirable. A purposefully designed combination of amphiphilic block copolymers including tunable lengths of hydrophilic polyethylene glycol (PEGm) and hydrophobic AIE polymer poly(tetraphenylethylene-trimethylenecarbonate) (P(TPE-TMC)n) has been studied at the air/liquid interface. The unique 2D assembly properties have been analyzed by thermodynamic measurements, UV-vis reflection spectroscopy and photoluminescence in combination with molecular dynamics simulations. The (PEG)m-b-P(TPE-TMC)n monolayers formed tunable 2D nanostructures self-assembled on demand by adjusting the available surface area. Tuning of the PEG length allows to modification of the area per polymer molecule at the air/liquid interface. Molecular detail on the arrangement of the polymer molecules and relevant molecular interactions has been convincingly described. AIE fluorescence at the air/liquid interface has been successfully achieved by the (PEG)m-b-P(TPE-TMC)n nanostructures. An experimentally simple 2D to 3D transition allowed to obtain 3D polymersomes in solution. This work suggests that engineered amphiphilic polymers for AIE may be suitable for selective 2D and 3D self-assembly for imaging and technological applications.

Purpose To study the effects of the density of folic acid (FA) on the hypoglycemic ability of FA-targeted polymersomes as oral insulin carriers. Also to study the change of the hypoglycemic effect of FA-targeted mixed polymersomes added with various mass ratio of d -α-tocopherol polyethylene glycol 1000 succinate (TPGS). Methods The FA-targeted polymersomes with different FA molar contents were prepared. The in vitro insulin release experiments in different media for FA-targeted polymersomes with various FA contents were studied. Their quantitative cellular uptake in Caco-2 cells was examined. The in vivo hypoglycemic activity of FA-targeted polymersomes was also studied with diabetic rats. The polymersomes with the optimal FA molar content was chosen to prepare mixed polymersomes with various TPGS contents. Results Among insulin-loaded FA-targeted polymersomes with four different FA molar contents, insulin-loaded polymersomes with 10% FA molar content (insulin-loaded 10%FA-Ps) showed the hightest cellular uptake and the best hypoglycemic response. In addition, the insulin-loaded FA-Ps/TPGS5:1 mixed polymersomes exhibited higher cellular uptake and better hypoglycemic response than the other two insulin-loaded mixed polymersomes adding TPGS did. Conclusions FA-Ps/TPGS5:1 could be a promising formulation for the oral administration of insulin.

Chemodynamic therapy (CDT) has been proposed to convert tumoral H2O2 into toxic hydroxyl radicals ( OH) via Fenton or Fenton-like reactions for antitumor efficacy, which is frequently limited by low H2O2 concentrations or lack of enough metal ions inside tumor tissues. In this report, we present ferrocene-containing responsive polymersome nanoreactors via loading glucose oxidase (GOD) and hypoxia-activable prodrug tirapazamine (TPZ) in the inner aqueous cavities. After intravenous injection, the polymersome nanoreactors with the optimized nanoparticle size of ~100 nm and poly(ethylene glycol) corona facilitate tumor accumulation. The tumor acidic microenvironment can trigger the permeability of the polymersome membranes to activate the nanoreactors and release the loaded TPZ prodrugs. Tumor oxygen and glucose can enter the polymersome nanoreactors and are transformed into H2O2 under the catalysis of GOD, which are further converted into OH via Fenton reaction under catalysis of ferrocene moieties. The oxygen consumption can aggravate tumor hypoxia to activate hypoxia-responsive TPZ prodrugs which can produce benzotriazinyl (BTZ) radicals and OH. All the produced radicals synergistically kill tumor cells via the amplified CDT and suppress the tumor growth efficiently. Thus, the ferrocene-containing responsive polymersome nanoreactors loading GOD and TPZ represent a potent nanoplatform to exert amplified CDT for improved anticancer efficacy.

Ovarian cancer (OC) is a high-mortality malignancy in women with a five-year survival rate of 30-40%. There is an urgent need to develop high-efficacy and low toxic treatments for OC. Herein, we report an appealing strategy that combines α3 integrin targeted polymersomes (A3-Ps) and targeted molecular drug, polo-like kinase 1 (PLK1) inhibitor volasertib (Vol) for dually targeted molecular therapy of OC in vivo. A3-Ps had good Vol loading of 7.7-8.0 wt.% and small size of 25-32 nm, depending on the density of α3 integrin binding peptide A3. Interestingly, cellular uptake studies using FITC-labeled Vol revealed that A3-Ps with 20% peptide gave 2.3 and 3.3-fold better internalization in SKOV-3 OC cells compared with non-targeted Ps and free Vol, respectively. Accordingly, Vol loaded in A3-Ps showed the best inhibitory activity to SKOV-3 cells with an IC50 of 49 nM, which was 3.5 times lower than free Vol. Importantly, the in vivo experiments demonstrated that A3-Ps-Vol proficiently repressed the growth of SKOV-3 tumors in mice while continuous tumor growth was observed for Ps-Vol and free Vol-treated mice. A3-Ps-Vol besides boosting anti-OC activity also reduced the systemic toxicity of Vol. This dually targeted molecular drug nanoformulation has appeared to be an especially potent and low toxic treatment modality for human ovarian cancers. Statement of significance Volasertib provides a potential molecular therapy for PLK1-positive advanced OC patients. The initial clinical outcomes, nevertheless, showed a suboptimal efficacy, possibly resulting from its fast clearance, deficient tumor deposition and dose-limiting toxicities. Here, we show for the first time that dually targeted molecular therapy of OC using α3 integrin-binding peptide-modified polymersomes as a vehicle gives markedly improved potency, better toleration, and depleted adverse effects in SKOV-3 tumor models, greatly outperforming free volasertib. This dually targeted strategy has emerged as an appealing treatment for malignant PLK1-positive ovarian tumors.

The delivery of therapeutics into sites of action by using cargo-delivery platforms potentially minimizes their premature degradation and fast clearance from the bloodstream. Additionally, drug-loaded stimuli-responsive supramolecular assemblies can be produced to respond to the inherent features of tumor microenvironments, such as extracellular acidosis. We report in this framework the use of pH-responsive polymersomes (PSs) manufactured using poly([N-(2-hydroxypropyl)] methacrylamide)35-b-poly[2-(diisopropylamino)ethyl methacrylate]75 as the building unit (PHPMA35-b-PDPA75). The self-assemblies were produced with desired size towards long circulation time and tumor accumulation (hydrodynamic diameter - DH ~ 100 nm), and they could be successfully loaded with 10% w/w DOX (doxorubicin), while maintaining colloidal stability. The DOX loaded amount is presumably mainly burst-released at the acidic microenvironment of tumors thanks to the pH-switchable property of PDPA (pKa ~ 6.8), while reduced drug leakage has been monitored in pH 7.4. Compared to the administration of free DOX, the drug-loaded supramolecular structures greatly enhanced the therapeutic efficacy with effective growth inhibition of EL4 lymphoma tumor model and 100% survival rate in female C57BL/6 black mice over 40 days. The approach also led to reduced cardiotoxic effect. These features highlight the potential application of such nanotechnology-based treatment in a variety of cancer therapies where low local pH is commonly found, and emphasize PHPMA-based nanomedicines as an alternative to PEGylated formulations.

Tumor microenvironment has been widely utilized for advanced drug delivery in recent years, among which hypoxia-responsive drug delivery systems have become the research hotspot. Although hypoxia-responsive micelles or polymersomes have been successfully developed, a type of hypoxia-degradable nanogel has rarely been reported and the advantages of hypoxia-degradable nanogel over other kinds of degradable nanogels in tumor drug delivery remain unclear. Herein, we reported the synthesis of a novel hypoxia-responsive crosslinker and the fabrication of a hypoxia-degradable zwitterionic poly(phosphorylcholine)-based (HPMPC) nanogel for tumor drug delivery. The obtained HPMPC nanogel showed ultra-long blood circulation and desirable immune compatibility, which leads to high and long-lasting accumulation in tumor tissue. Furthermore, HPMPC nanogel could rapidly degrade into oligomers of low molecule weight owing to the degradation of azo bond in hypoxic environment, which leads to the effective release of the loaded drug. Impressively, HPMPC nanogel showed superior tumor inhibition effect both in vitro and in vivo compared to the reduction-responsive phosphorylcholine-based nanogel, owing to the more complete drug release. Overall, the drug-loaded HPMPC nanogel exhibits a pronounced tumor inhibition effect in a humanized subcutaneous liver cancer model with negligible side effects, which showed great potential as nanocarrier for advanced tumor drug delivery., Graphical abstract HPMPC nanogel shows ultra-long blood circulation without causing the accelerated blood clearance phenomenon, which leads to enhanced accumulation in tumor tissue. HPMPC nanogel holds the drug firmly in blood or normal tissue whereas releases the drug effectively in tumor environment, leading to improved therapeutic effect and negligible side effects.Image 1

Summary Synthetic cells, also referred to as protocells, artificial cells, or minimal cells, are a type of engineered entities that mimic the features of biological cells and are promising for recapitulating cellular features and behaviors. Inspired by the confined and complex intracellular environment, emulsion droplets are among the most promising candidates because droplets serve as templates for the construction of coacervates, vesicles, polymersomes, and colloidosomes. These synthetic cells pave the way for recalling the minimal living properties, elucidating fundamental cell biology problems, and bringing forth novel opportunities in advanced biotechnologies. Here, we review the latest progress made in droplet-templated synthetic cells with emphasis on the principles of cell activities, construction techniques involving tailoring droplet structures and contents, and the functionalities of the resultant cell-mimic constructs, as well as their applications. Finally, we discuss the current challenges and future possibilities of this field.

Utilization of unique acidic environment in various disease sites has been quite advantageous in targeted drug delivery. Among the widely explored pH-sensitive moieties such as hydrazone, orthoester, imine, vinylether, etc., the acetal bearing compounds are one of the most explored entities in targeted and improved drug delivery to treat disease conditions at the preclinical stage. This review addresses the design and synthesis of various acetal-based polymers as pH-responsive nano-drug delivery systems in the form of micelles, polymersomes, nanoplexes and polymeric and solid lipid nanoparticles for biomedical applications. The review will identify potential advantages, key challenges and future prospects of acetal-based pH-responsive drug delivery systems. The novel developments, strategies and suggestions described may guide the formulation scientists to optimize acetal-based pH-responsive drug delivery systems as an approach to treat various diseases.

Stimuli-responsive anticancer drug delivery vehicles have attracted increasing attention in nanomedicine. However, controlled drug release in vivo is still an important challenge, as traditional stimuli lack maneuverability. To solve this problem, we designed an ultrasound and pH-responsive polymersome by self-assembly of poly(ethylene oxide)-block-poly(2-(diethylamino)ethyl methacrylate)-stat-poly(methoxyethyl methacrylate) [PEO-b-P(DEA-stat-MEMA)], where PEO acts as the corona-forming block, DEA acts as the endosomal escape segment, and MEMA acts as the ultrasound-responsive segment. This strategy combines the advantages of noninvasive ultrasonic stimulus which can be applied from outside to any organ regardless of depth, and the weakly acidic microenvironment of tumor tissue. In vitro experiments confirmed excellent endosomal escape ability, on-demand drug release behavior, low cytotoxicity, and high intracellular delivery efficiency of polymersomes. In vivo antitumor tests revealed that in the presence of sonication, the anticancer drug was released at an accelerated rate from these ultrasound-responsive polymersomes, and the DOX-loaded polymersomes + sonication group significantly inhibited tumor growth (95% reduction in tumor mass) without any side effects. Overall, this ultrasound-responsive polymersome provides us with a fresh insight into designing next-generation stimuli-responsive drug carriers with better maneuverability and higher chemotherapeutic efficiency.

Glioblastoma with intracranial infiltrative growth remains an incurable disease mainly owing to existence of blood brain barrier (BBB) and off-target drug toxicity. RNA interference (RNAi) with a high specificity and low toxicity emerges as a new treatment modality for glioblastoma. The clinical application of RNAi technology is, however, hampered by the absence of safe and brain-targeting transfection agents. Here, we report on angiopep-2 peptide-decorated chimaeric polymersomes (ANG-CP) as a nontoxic and brain-targeting non-viral vector to boost the RNAi therapy for human glioblastoma in vivo. ANG-CP shows excellent packaging and protection of anti-PLK1 siRNA (siPLK1) in its lumen while quickly releasing payloads in a cytoplasmic reductive environment. Notably, in vitro experiments demonstrate that ANG-CP can effectively permeate the bEnd.3 monolayer, transport siRNA into the cytosol of U-87 MG glioblastoma cells via the LRP-1-mediated pathway, and significantly silence PLK1 mRNA and corresponding oncoprotein in U-87 MG cells. ANG-CP greatly prolongs the siPLK1 circulation time and enhances its accumulation in glioblastoma. RNAi with siPLK1 induces a strong anti-glioblastoma effect and significantly improves the survival time of glioblastoma carrying mice.

The poly lactic-co-glycolic acid copolymer has become one of the most widely used synthetic macromolecules available for use in nanoscale drug delivery studies because of its biocompatibility and biodegradability. In this study, using computational molecular dynamics methods, combinations of polymer with different amounts of lactic and glycolic acid were compared for loading hydrophilic and hydrophobic of Gemcitabine and Camptothecin. These simulations were carried out in different ratios of the drug to the polymer. The results show that in all monomeric ratios, the amount of Camptothecin loading is higher, but on the other hand, the energy of the interaction of Gemcitabine with copolymer is greater, which can reduce its release rate from the system. By increasing the amount of glycolic acid in its system, it's the flexibility is increased and the formation of nanoparticles is also increased. Increasing the formation of nanoparticles leads to increase of the amount of drug loading of Gemcitabine. Conversely, with the increase in lactic acid content, the polymer's flexibility is diminished due to methyl group steric hindrance and the formation of nanoparticles is impaired. The results also show that for the formation of polymersomes, the drugs are first attached to the polymers, and then these compounds form the final nanoparticles as close as possible. Finally, this study suggests that poly lactic-co-glycolic acid is more suitable for loading hydrophobic drugs in any ratio of monomers. However, with increasing glycolic acid levels, its ability to load hydrophilic drugs also reaches a reasonable level.

The delivery of therapeutics to the brain is greatly hampered by the blood-brain barrier (BBB). The use of nanoparticles that can cross the BBB via the process of receptor-mediated transcytosis at blood-brain barrier endothelial cells seems a promising strategy to transport therapeutics into the brain. To screen for suitable nanocarriers, and to study the process of transcytosis, a cultured polarized monolayer of brain microvascular endothelial cells on an extracellular matrix-coated porous membrane filter is widely used as an in vitro BBB model. However, due to the adhesion of numerous types of nanoparticles to the membrane filter and within the filter pores, such a model is unsuitable for the quantification of transendothelial delivery of nanoparticles. Hence, there is a pressing need for a filter-free in vitro BBB model. Ideally, the model is inexpensive and easy to use, in order to allow for its wide use in nanomedicine and biology laboratories around the world.Here, we developed a filter-free in vitro BBB model that consists of a collagen gel covered with a monolayer of brain microvascular endothelial (hCMEC/D3) cells. The paracellular leakage of differently sized dextrans and the transcellular transport of LDL were measured to demonstrate the validity of the filter-free model. Finally, the transendothelial delivery of fluorescently-labelled PEG-P(CL-g-TMC) polymersomes that were functionalized with GM1-targeting peptides was assessed by fluorescence spectroscopy measurement of the luminal, cellular, and abluminal parts of the filter-free BBB model. Our data confirm the effectiveness of the G23 peptide to mediate transport of polymersomes across the BBB and the suitability of this filter-free in vitro model for quantification of nanoparticle transcytosis.

Peripheral Arterial Occlusive Disease (PAOD) is an aging disease that affects the quality of life of many people by its intermittent claudication and critical limb ischemia presentations. Traditional treatment and management of PAOD are asking patients to make a life change and medication with antiplatelet, statins and cilostazol, which decrease the possibility of clot formation. Our strategy has employed a magnetic Fe3O4-PLGA polymersome to carry the cilostazol into the ischemic area by magnetic attraction following remote-control drug release through low-energy ultrasound exposure. In the animal studies, the cilostazol-loaded Fe3O4-PLGA polymersomes were injected and accumulated at ischemic leg through magnetic attraction. Then, using a clinical-use ultrasound machine the leg was irradiated to forward cilostazol release from the accumulated polymersomes. Dramatically, we found an observable result of bloody flux recovery in the leg after 7 days compared to the non-treated leg that showed no evidence of the blood recovery.

Combination cancer chemotherapy provides an important treatment tool, both as an adjuvant and neoadjuvant treatment, this shift in focus from mono to combination therapies has led to increased interest in drug delivery systems (DDS). DDSs, such as polymersomes, are capable of encapsulating large amounts of multiple drugs with both hydrophilic and hydrophobic properties simultaneously, as well as offering a mechanism to combat multi drug resistant cancers and poor patient tolerance of the cytotoxic compounds utilised. In this article, we report the formulation and evaluation of a novel electroneutral polymersome capable of high encapsulation efficacies for multiple drugs (Doxorubicin, 5-Fluorouracil and leucovorin). The in-vivo biodistribution of the polymersome were established and they were found to accumulate largely in tumour tissue. Polymersome encapsulating the three chemotherapeutic drugs were assessed both in-vitro (BxPC-3 cell line) and in-vivo (following intratumoral and intravenous administration) and compared with the same concentration of the three drugs in solution. We report better efficacy and higher maximum tolerated dose for our combination drug loaded polymersomes in all experiments. Furthermore, intratumorally injected combination drug loaded polymersomes exhibited a 62% reduction in tumour volume after 13 days when compared with the free combination solutions. A smaller differential of 13% was observed for when treatment was administered intravenously however, importantly less cardiotoxicity was displayed from the polymersomal DDS. In this study, expression of a number of survival-relevant genes in tumours treated with the free chemotherapy combination was compared with expression of those genes in tumours treated with the polymersomes harbouring those drugs and the significance of findings is discussed. Statement of significance The shift in focus from mono to combination chemotherapies has led to an increased interest in the role of drug delivery systems (DDS). Liposomes, although commercialized for mono therapy, have lower loading capacities and stability than their polymeric counterpart, polymersomes. Polymersomes are growing in prevalence as their advantageous properties are better understood and exploited. Here we present a novel polymersome for the encapsulation of three anticancer compounds. This is the first time this particular polymersome has been used to encapsulate these three compounds with both an in-vitro and in-vivo evaluation carried out. This work will be of interest to those in the field of combination therapy, drug delivery, drug toxicity, multidrug resistance, liposomes, DDS and polymersomes.

Summary: Polymersomes are vesicles formed by the self-assembly of amphiphilic copolymers in water. They represent one of the most promising alternatives of natural vesicles as they add new possibilities in the amphiphiles' molecular engineering of aqueous compartments. Here we report the design of polymersomes using a bottom-up approach wherein self-assembly of amphiphilic copolymers poly(2-(methacryloyloxy) ethyl phosphorylcholine)-poly(2-(diisopropylamino) ethyl methacrylate) (PMPC-PDPA) into membranes is tuned using pH and temperature. We report evolution from disk micelles, to vesicles, to high-genus vesicles (vesicles with many holes), where each passage is controlled by pH switch or temperature. We show that the process can be rationalized, adapting membrane physics theories to disclose scaling principles that allow the estimation of minimal radius of vesiculation as well as chain entanglement and coupling. This approach allows us to generate nanoscale vesicles with genus from 0 to 70, which have been very elusive and difficult to control so far. : Polymer Chemistry; Materials Chemistry; Colloids Subject Areas: Polymer Chemistry, Materials Chemistry, Colloids

The synthesis of smart stimuli-responsive polymeric materials for nanomedicine applications has attracted the interest of a large number of scientists that focuses on the effective encapsulation of pharmaceutical compounds and control of their biodistribution. The development of multifunctional polymeric materials is mainly guided by the goal of achieving active compounds which selectively target the pathological sites, therefore minimizing systemic side effects. These materials are divided in two categories based on their mode of administration: the first is based on systemic administration, while the second relies on localized mode of action. Polymersomes are nanocarriers that are delivered through the blood compartment and are the best systems to carry both hydrophilic drugs in their interior hollow space or/and hydrophobic drugs encapsulated in their hydrophobic layer. Polymeric hydrogels on the other hand are systems for localized drug delivery of both kinds of pharmaceuticals, depending on their solubility. Even though a large number of polymeric materials that form either nanocarrier or hydrogel delivery systems has been investigated, a surprisingly small subset of these technologies has demonstrated potentially curative preclinical results, and fewer have progressed towards commercialization. One of the most promising classes of polymeric materials for drug delivery applications is polypeptides, which combine the properties of the conventional polymers with the 3D structure of natural proteins such as α-helices and β-sheets. In this article, the synthetic pathways followed to develop well-defined stimuli-responsive polymer delivery systems based on polypeptides that have been prepared through ring-opening polymerization (ROP) of N-carboxyanhydrides are reviewed, including a discussion of their in vivo and in vitro efficacy. This review is limited to systems presented over the last eighteen years.

pH-responsive polymersomes were obtained by self-assembling of a carboxyl-terminated PEG amphiphile achieved via esterification of PEG diacid with PEG40stearate. The obtained vesicular systems had spherical shape and a mean diameter of 70 nm. The pH sensitivity was assessed by measuring the variations of particles mean diameter after incubation in media mimicking the physiological (pH 7.4) or tumor (pH 5.0) conditions, recording a significant increase of the vesicles dimensions at acidic pH. The ability of the polymersomes to carry both hydrophobic and hydrophilic drugs was evaluated by loading the vesicles with curcumin and methotrexate, respectively, obtaining high encapsulation efficiencies and pH-dependent release profiles. The drug-loaded polymeric vesicles exhibited improved cytotoxic potential against MCF-7 cancer cell line and were found to be highly hemocompatible. Finally, cellular uptake experiments on MCF-7 cancer cells were conducted to demonstrate the ability of the designed polymersomes to enhance drug penetration inside the cells.

The long-term fate of biomedical nanoparticles after endocytosis is often only sparsely addressed in vitro and in vivo, while this is a crucial parameter to conclude on their utility. In this study, dual-fluorescent polyisobutylene-polyethylene glycol (PiB-PEG) polymersomes were studied for several days in vitro and in vivo. In order to optically track the vesicles' integrity, one fluorescent probe was located in the membrane and the other in the aqueous interior compartment. These non-toxic nanovesicles were quickly endocytosed in living A549 lung carcinoma cells but unusually slowly transported to perinuclear lysosomal compartments, where they remained intact and luminescent for at least 90 h without being exocytosed. Fluorescence-assisted flow cytometry indicated that after endocytosis, the nanovesicles were eventually degraded within 7–11 days. In zebrafish embryos, the polymersomes caused no lethality and were quickly taken up by the endothelial cells, where they remained fully intact for as long as 96 h post-injection. This work represents a novel case-study of the remarkable potential of PiB-PEG polymersomes as an in vivo bio-imaging and slow drug delivery platform.

Recently, the bottom-up assembly of a synthetic cell has emerged as a daring novel approach that can be expected to have major impact in generating fundamental insight in the organization and function of actual biological cells, as well as in stimulating a broad range of applications from drug delivery systems to chemical nanofactories. A crucial feature of any such synthetic cell is the architectural scaffold that defines its identity, compartmentalizes its inner content, and serves as a protective and selective barrier against its environment. Here we review a variety of potential scaffolds for building a synthetic cell. We categorize them as membranous structures (liposomes, fatty acid vesicles, polymersomes), emulsions (droplets and colloidosomes), and membrane-less coacervates. We discuss recent advances for each of them, and explore their salient features as candidates for designing synthetic cells.

Sorafenib (SFN), a hydrophobic anticancer drug, has several limitations predominantly poor aqueous solubility and hepatic first-pass effect, limiting its oral delivery that results into several other complications. Present study aims to develop Sorafenib loaded polymersomes using poly butadiene block poly ethylene oxide (PB-b-PEO), an amphiphilic co-block polymer. Prior to drug loading, critical aggregate concentration (CAC) of polymer was calculated for stable formulation synthesis. The developed SFN loaded PB-b-PEO polymersomes (SFN-PB-b-PEO, test formulation) characterized by DLS and cryo-TEM showed particle size 282 nm, polydispersity (PDI) of less than 0.29 and membrane thickness of about 20 nm. SFN-PB-b-PEO polymersomes demonstrated encapsulation efficiency of 71% and showed sustained drug release up to 144 h. Formulation remained stable for 3 months in suspension form. In vitro cytotoxicity against HepG2 cells showed 1.7 folds improved toxicity compared to SFN suspension. In addition, oral administration of SFN-PB-b-PEO polymersomes in BALB/c mice showed increased Cmax and AUC0-96 by 1.7 and 2.77-fold respectively (p

In the present paper we show the preparation of polymersomes using ABA triblock copolymers with poly(dimethylsiloxane) and poly(2-methyloxazoline) blocks with the incorporation of SoPIP2;1 aquaporin in their structure. The presence of the protein in the polymersome membrane was demonstrated using imaging techniques, and the conformation of the protein into the membranes was assessed using Raman spectroscopy and attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR). The results suggest the presence of SoPIP2;1 aquaporin in a functional form which could be used for the preparation of Aquaporin-based membranes for water purification via reverse osmosis without the needed of liposome or lipidic-based reconstitution media.

Amplification of electrochemical signal in order to betterment of limit of detection in determination of biomarkers has an important role in early detection of some dangerous diseases such as cancers. For this purpose, in this research, two types of poly (styrene)-block-poly (acrylic acid) amphiphilic copolymer (PS61-b-PAA596 and PS596-b-PAA61) were synthesized by controlled radical polymerization method via reversible addition-fragmentation chain transfer polymerization (RAFT) technique. Chemical structure of block copolymers was confirmed by FT-IR spectroscopy and their surface morphology was assessed by scanning electron microscopy (SEM). Self-assembly of these block copolymers into polymeric vesicles (polymersomes), loading and release efficiency of methylene blue as an electroactive indicator were investigated in DMF and THF solvents. On the basis of our findings PS61-b-PAA596 has better capability for loading and release of MB than PS596-b-PAA61. Then the obtained methylene blue-loaded polymersome successfully used for development of an aptasensor toward determination of trace amounts of myoglobin. The proposed aptasensor showed a wide linear range from 1.0 aM to 1.0 μM with an ultra-low detection limit of 0.73 aM. Applying this amplification strategy, determination of myoglobin in real samples was successfully performed.

Cancer has since long remained a cause of concern which has eventually become leading cause of mortality. It was in the late 90 s, when polymersomes were identified as a platform for therapeutic delivery. They are smart self-assembled nanostructures that are designed as a result of block copolymers assembly which can be of versatile nature and hence their properties and stability can be altered based on the polymer type. Polymersomes are stable vesicular structure that encompass the unique ability to load hydrophobic, hydrophilic molecules or the combination of both. Apart from drug delivery they also represent an optimal choice for diagnostic purposes and as tools of imaging. For anticancer therapy, polymersomes can be conjugated with ligands or peptides meant for targeting specific receptors of malignant cells, which in turn helps in reducing off target toxicity and in enhancing the overall therapeutic effect of drug. Additionally, their properties can be altered and can be designed as stimuli responsive polymersomes which proves to be advantageous in chemotherapy of cancer. Owing to these multifaceted characteristics they have fetched the attention of several researchers for solving the problem of solubility and advancing the delivery of taxanes derivative drugs paclitaxel and docetaxel. Although there are numerous limitations related to biosafety and large scale reproducibility that still hampers it use clinically and once these challenges are resolved they can be brought to translational use. This review covers the positive aspects of use of polymersomes as carriers for taxanes drugs along with the results obtained from the experiments performed on different cancer cell lines. It further covers the existing limitations that still needs to be addressed and the future prospects of the use of these vesicular nanostructures in anticancer therapy.

Combined experimental and simulation investigations have provided molecular level insights into 5-iodo-2'-deoxyuridine (IUdR) loading behavior for the novel PEG/PCL/PEG polymersome-like carriers in mixed dichloromethane/N,N-dimethylformamide (DCM/DMF) solvent. As with the experiments, a novel approach was applied for layer by layer tailoring of polyethylene glycol (PEG) and polycaprolactone (PCL) as PEG/PCL/PEG copolymer on the surface of magnetite nanoparticles (MNPs) by click chemistry. Experimental results indicated that IUdR, as an anti-cancer drug, could be encapsulated up to 80% EE in this nanocarrier and could be in-vitro released up to 90% during 120h. Computational studies, on the other hand, provide molecular level insights into the optimal performance of the carrier in terms of drug "Dispersion" and "Diffusion" patterns in equimolar DCM/DMF solvent. Molecular dynamics simulations of the system in four distinct solvation scenarios including pure DCM, mixed DCM/DMF, pure DMF and water, have proven that while hydrophobic solvents give rise to better "dispersion" of drugs, hydrophilic solvents lead for drug molecules to penetrate into the carrier and improve "diffusion" properties. Optimal conditions for drug encapsulation, as also confirmed through experiments, was observed for mixed DCM/DMF solvent in terms of proper diffusion and well dispersion. While drug "aggregates" were observed in DCM, poorly stable drug molecules with lowered penetrations were observed in pure DMF. Proper release properties with IUdR molecules staying on the surface of the carrier was also observed in water. The interesting role of the star-linear architecture was further scrutinized through distinctions made through analysis of interactions between IUdR molecules with "inner" and "outer" PEG sections.

This review focuses on therapeutic applications of various drug delivery nanovehicles encapsulated with the anti-cancer drug, methotrexate (MTX). Currently, a number of studies have been conducted to explore advanced chemotherapeutic systems with nonviral nanovehicles such as liposomes, polymeric micelles, polymersomes, solid lipids, dendrimers, porous metal and metal oxide particles, carbons with various nanostructures, and layered double hydroxides (LDHs). Out of various anticancer drugs, MTX was hybridized with those drug delivery nanovehicles not only to overcome its adverse effects, but also to induce advanced functions into those hybrid systems, such as enhanced solubility, controlled release, passive and active targeting, aimed to eventually enhance bioavailability of MTX. In particular, two dimensional LDHs are introduced rather in detail as one family of inorganic nanovehicles, since the therapeutic efficacies for MTX-LDHs have been systematically studied with in vivo orthotopic models, those which are clinically better correlated and therefore, more efficient to predict drug efficacy and toxicity than the standard one like xenograft model. Attempts are also made here to provide therapeutic results on chemically well defined MTX-LDH advanced drug delivery systems, such as their in vitro and in vivo targeting functions, biocompatibility and nanotoxicities and ability to overcome drug resistance. In addition, recent advances and challenges in advanced hybrid DDSs are discussed from the viewpoint of state-of-the-art nanomedicine.

Doxil® is the first FDA-approved anti-cancer nano-drug. Notably, no targeted liposomal formulation has advanced to clinical stage despite tremendous work undertaken, partly due to a low stability of liposomes. Here, we report on novel lipopepsomes self-assembled from poly(ethylene glycol)-b-poly(α-aminopalmitic acid) as a stable and versatile alternative to liposomes for highly efficient encapsulation and tumor-targeted delivery of doxorubicin hydrochloride (Dox·HCl). Interestingly, lipopepsomes could be easily decorated with 20mol% cRGD peptide and loaded with 17.4wt% Dox·HCl, giving cRGD-LPP-Dox with a small size of ~80nm. cRGD-LPP-Dox exhibited a high stability against 10% FBS and restrained drug release under physiological conditions. Flow cytometry, confocal microscopy and MTT assays using αvβ3-overexpressing A549 tumor cells showed obviously more efficient uptake and higher anticancer activity for cRGD-LPP-Dox than for non-targeted LPP-Dox and clinically used liposomal Dox (Lipo-Dox) controls. Notably, cRGD-LPP-Dox exhibited markedly enhanced toleration and tumor accumulation than Lipo-Dox. The therapeutic studies demonstrated that cRGD-LPP-Dox achieved effective suppression of orthotopic A549 human lung tumor in nude mice, resulting in significantly improved survival rate as compared to LPP-Dox and Lipo-Dox groups. Lipopepsomes with small size, efficient loading of Dox·HCl, high stability and versatile ligand decoration have appeared as a highly attractive nanoplatform for targeted tumor chemotherapy.

A series of compounds, in which exo-norbornene scaffold appended with amino acids, was synthesized. These compounds underwent ring opening metathesis polymerization (ROMP) catalyzed by Grubbs second generation ruthenium catalyst to form polymers with bottlebrush architecture. Four different polymers P1-P4 were synthesized, differing in number of lipid units and degree of branching. These polymers were well-characterized by 1H NMR and gel permeation chromatographic (GPC) techniques. These peptide-based homopolymers showed an exceptional ability to self-assemble to form polymersomes. The self-assembled structures were characterized by various ultramicroscopic techniques such as scanning electron microscopy (SEM), transmission electron microscopy (TEM) and atomic force microscopy (AFM). The entrapment capability of polymer vesicles was confirmed by dye-encapsulation studies.

In this work, permeability of polymersomes was quantified by fluorescence enhancement. The polymersomes were prepared from poly(ethylene glycol)-b-poly(e-caprolactone) (PEG-PCL), and an acid-sensitive hydrophobic dye borondipyrromethene (BODIPY) was encapsulated into the membrane of polymersomes. H+ from trifluoroacetic acid (TFA) would diffuse into the membrane of polymersomes to enhance the fluorescence of BODIPY. Intensity of the enhanced fluorescence could be used for quantifying the H+ permeability of polymersomes. In addition, poly(e-caprolactone) (PCL) was used to control the permeability ability of the membrane. Such quantitative information on the molecular diffusion of polymersomes is of fundamental importance to many of their potential applications, e.g., nanoreactors and drug delivery.

We develop a new method to prepare block copolymer vesicles with high loading capacity of drugs which can then be released in a controlled manner. The block copolymers, including PS-b-PAA, PS-b-PEO, and biocompatible PCL-b-PEO, can directly self-assemble into vesicles in aspirin and encapsulate aspirin by solvent annealing with ethanol which imparts mobility to the originally solid block copolymers and aspirin molecules. Aspirin associates with the hydrophilic blocks after premixing, firstly leading to the formation of bilayer structures. During solvent annealing, the bilayers are wrapped into vesicles to enclose aspirin that fills the cores of the vesicles. The interactions between block copolymers and aspirin were probed by FT-IR, and the formation of aspirin-loaded vesicles were confirmed by transmission electron microscopy and dynamic light scattering. The loading content of aspirin in the extracted vesicles is 59 ± 5%, higher than that of conventional vesicles formed in liquid systems with dilute drugs. The release rate and final release amount of aspirin from vesicles in aqueous solutions can be controlled by addition of different amount of n-dioxane or by changing pH values.

Real-time reverse transcriptase-polymerase chain reaction (RT-PCR)-based assays are the gold standard for virus diagnosis. Point-of-care (POC) technologies have shown great progress during this period. Herein, we propose a novel fuchsine dye-loaded polymersome for a colorimetric paper-based dot blot spike protein diagnostic assay for COVID-19 via smartphone-assisted sensing. The prepared platform aimed to create an adaptable tool that competes with traditional nanoparticle-based assays employing gold and silver. Analytical characterization and application of the testing platform showed high sensitivity (10 times better than gold nanoparticles), stability, fast turnaround, and reproducibility. The potential and possibilities demonstrated by the current platform could be observed in its adaptability for different markers and pathologies. In addition, smartphone-assisted sensing emphasizes the ability to use the tool at home by common peoples which can lower the burden on the healthcare facilities and reach more underdeveloped regions., Research Foundation of Ege University, Turkey [TOA-2020-21862]; Republic of Turkey, Ministry of Development [2010K120810/2020K12150700, 2016K121190], The research project was supported by the Research Foundation of Ege University, Turkey (Project number: TOA-2020-21862) . Republic of Turkey, Ministry of Development provided the support for the infra-structure of EGE MATAL (Ege University/Izmir) via 2010K120810/2020K12150700 and 2016K121190 grants.

Controlling the traffic of molecules and ions across membranes is a critical feature in a number of biologically relevant processes and highly desirable for the development of technologies based on membrane materials. In this paper, ion transport behavior of hybrid lipid/polymer membranes was studied in the absence and presence of ion transfer agents. A pH-sensitive fluorophore was used to investigate ion (H + /OH − ) permeability across hybrid lipid/polymer membranes as a function of the fraction of amphiphilic block copolymer. It was observed that vesicles with intermediate lipid/polymer ratios tend to be surprisingly more permeable to ion transport than the pure lipid or pure polymer vesicles. Hybrid vesicle permeability could be further modulated with valinomycin, nigericin, or gramicidin A, which significantly expedite the dissipation of externally-imposed pH gradients by facilitating the transport of the rate-limiting co-ions ( e.g. K + ) ions across the membrane. For gramicidin A, ion permeability decreased with increasing polymer mole fraction, and the method of introduction of gramicidin A into the membrane played an important role. Strategies to incorporate biofunctional molecules and facilitate their activity in synthetic systems are highly desirable for developing artificial organelles or other synthetic compartmentalized structures requiring control over molecular traffic across biomimetic membranes.

Nanoparticles, such as polymersomes, can be directed to the hepatic asialoglycoprotein receptor to achieve targeted drug delivery. In this study, we prepared asialofetuin conjugated polymersomes based on the amphiphilic di-block copolymer poly(dimethylsiloxane)-b-poly(2-methyloxazoline) (PDMS-b-PMOXA). They had an average diameter of 150nm and formed monodisperse vesicles. Drug encapsulation and sustained release was monitored using the hydrophilic model compound carboxyfluorescein. Asialoglycoprotein receptor specific uptake by HepG2 cells in vitro was energy dependent and could be competitively inhibited by the free targeting ligand. Mechanistic uptake studies revealed intracellular trafficking of asialofetuin conjugated polymersomes from early endosomes and to the lysosomal compartment. Polymersomes showed no toxicity in the MTT assay up to concentrations of 500μg/mL. In addition, acute toxicity and tolerability of our PDMS-b-PMOXA polymersome formulations was assessed in vivo using zebrafish embryos as a vertebrate screening model. In conclusion, a hepatocyte specific drug delivery system was designed, which is safe and biocompatible and which can be used to implement liver-specific targeting strategies.

Alpha-emitting radionuclides like actinium-225 (225Ac) are ideal candidates for the treatment of small metastasised tumours, where the long half-life of 225Ac enables it to also reach less accessible tumours. The main challenge lies in retaining the recoiled alpha-emitting daughter nuclides, which are decoupled from targeting agents upon emission of an alpha particle and can subsequently cause unwanted toxicity to healthy tissue. Polymersomes, vesicles composed of amphiphilic block copolymers, are capable of transporting (radio)pharmaceuticals to tumours, and are ideal candidates for the retention of these daughter nuclides. In this study, the Geant4 Monte Carlo simulation package was used to simulate ideal vesicle designs. Vesicles containing an InPO4 nanoparticle in the core were found to have the highest recoil retention, and were subsequently synthesized in the lab. The recoil retention of two of the daughter nuclides, namely francium-221 (221Fr) and bismuth-213 (213Bi) was determined at different vesicle sizes. Recoil retention was found to have improved significantly, from 37 ± 4% and 22 ± 1% to 57 ± 5% and 40 ± 2% for 221Fr and 213Bi respectively for 100nm polymersomes, as compared to earlier published results by Wang et al. where 225Ac was encapsulated using a hydrophilic chelate (Wang et al. 2014). To better understand the different parameters influencing daughter retention, simulation data was expanded to include vesicle polydispersity and nanoparticle position within the polymersome. The high retention of the recoiling daughters and the 225Ac itself makes this vesicle design very suitable for future in vivo verification.

In this study, we prepared tetraiodothyroacetic acid (tetrac) conjugated PEG-PLGA polymersomes for the targeted delivery of camptothecin to colon adenocarcinoma. Tetrac, which binds to integrin αvβ3 with high affinity and specificity, was covalently conjugated to the surface of the PEGylated polymersomal formulation of camptothecin (CPT). The hydrodynamic and morphological properties of the prepared system were evaluated using TEM (transmission electron microscopy), SEM (scanning electron microscopy) and DLS (dynamic light scattering) experiments. Camptothecin was encapsulated in the polymersomal system with encapsulation efficiency and loading content of 84 ± 10.12 and 4.2 ± 0.82, respectively. The in vitro release profile of camptothecin from the polymersomal formulation revealed the sustained release pattern. In vitro cytotoxicity experiments confirmed that the tetrac-conjugated camptothecin loaded-polymersomes had higher cellular toxicity towards integrin-overexpressed HT29 and C26 colorectal cancer cells than integrin-negative CHO cell line. The in vivo tumor inhibitory effect of tetrac-conjugated camptothecin loaded-polymersomes demonstrated an enhanced therapeutic index of integrin targeted polymersomal formulation over both non-targeted polymersomal formulation and free camptothecin in C26 tumor bearing mice. The obtained results demonstrated that the prepared tetrac-conjugated polymersomes were able to control the release of camptothecin, and significantly increase the therapeutic index of compthotecin. This study demonstrates the versatility of integrin-targeted tetrac-conjugated PEG-PLGA polymersomal formulation as an anti-cancer nano-pharmaceutical platform.

Polymer vesicles formed by a pair of oppositely charged diblock copolyelectrolytes (PICsomes) are considered as a good alternative to polymersomes formed by amphiphilic copolymers. Here, we report on inherent stability and in vitro biocompatibility of PICsomes prepared from a pair of oppositely charged zwitterionic-ionic copolymers, in which the ionic block is a strong polyelectrolyte. Our results demonstrated that the PICsomes are highly stable over a wide range of pH and temperatures. Direct microscopic observations revealed that the PICsomes retain their morphology in the presence of human serum. In vitro studies using human skin fibroblasts (HSFs) showed that the polymer vesicles are not cytotoxic and do not affect cell proliferation and adhesion. A model hydrophilic dye was effectively incorporated into the PICsomes by simple mixing. Using confocal microscopy observations, we demonstrated that the dye-loaded PICsomes are efficiently internalized by the cells and are located predominantly in endo/lysosomal compartments. Thus, the PICsomes have promising potential for use as nanocontainers for substances of biomedical interest.

Polymer capsules, fabricated either with the aid of a sacrificial template or via the self-assembly of block copolymers into polymer vesicles (polymersomes), have attracted a great deal of attention for their potential use as micro-/nanoreactors and artificial organelles for therapeutic applications. Compared to other biomedical applications of polymer capsules, such as drug delivery vehicles, where the polymer shell undergoes irreversible disruption/rupture that allows the release of the payload, the polymer shell in polymer micro-/nanoreactors has to maintain mechanical integrity while allowing the selective diffusion of reagents/reaction products. In the present review, strategies that permit precise control of the permeability of the polymer shell while preserving its architecture are documented and critiqued. Together with these strategies, specific examples where these polymer capsules have been employed as micro-/nanoreactors as well as approaches to scale-up and optimize these systems along with future perspectives for therapeutic applications in several degenerative diseases are elucidated.

Carboplatin is one of the few platinum-based antitumor drugs used worldwide. Unfortunately, systemic carboplatin therapy is limited by its dose-related myelosuppression. In this study, a viable way to reduce the serious myelotoxicity of carboplatin while improving its therapeutic efficacy using amino-functionalized polyphosphazene vesicles is reported. First, three polyphosphazenes with different amino content were synthesized by amidating hydrophobic side groups; these polyphosphazenes could self-assemble into polymersomes with similar particle size and morphology. Based on FTIR analysis, hydrogen bonding interactions between the polymeric carriers and carboplatin were validated and shown to predominantly contribute to the significant improvement of drug loading in polymersomes. Therefore, it turned out that the amino level of polymers played a substantial role in carboplatin encapsulation. Then, PEAP-2-C polymersomes were optimized for further experimental verification to achieve depressed carboplatin-induced myelotoxicity as well as promote curative effects against CT-26 colon adenocarcinoma. These results in vitro and in vivo proved that amino-functionalized polyphosphazene vesicles have great potential for carboplatin delivery in the application of cancer therapy.

Poly(e-caprolactone)-b-poly(ethylene glycol)-b-poly(e-caprolactone) (PCL-b-PEG-b-PCL, PCEC) triblock copolymers have been widely investigated in last several decades. Here, by altering the weight ratio of monomers in ring-opening polymerization, a series of PCEC triblock copolymers with varying hydrophobicity were synthesized, which were characterized by FTIR, 1H NMR, GPC and DSC. When PCEC copolymers with different weight ratios of PCL/PEG were dispersed in different aqueous solutions, they could self-assemble and form two distinctive nanoparticular structures: micelles or polymersomes. We then chose paclitaxel (PTX) as the model drug and encapsulate PTX into PCEC polymeric micelles and polymersomes. The physicochemical characterizations of the nanoparticles such as morphology, the size and distribution, zeta potential, drug loading content, and encapsulation efficiency were also performed. Our results showed that polymeric micelles or polymersomes from PCEC both displayed narrow size distributions and could achieve high drug loading efficiencies. In vitro cellular uptake results suggested that Nile Red loaded polymeric micelles or polymersomes displayed more internalization after 24 h incubation than those after 4 h incubation. These findings suggest that polymeric micelles and polymersomes based on PCL-b-PEG-b-PCL copolymers have great potential to effectively delivery hydrophobic drugs.

Emulsion droplets with well-controlled topologies are used as templates for forming vesicles with either symmetric or asymmetric membranes. This review summarizes the available technology to produce these templates, the strategies and critical parameters involved in the transformation of emulsion droplets into vesicles, and the properties of the generated vesicles, with a special focus on the composition and material distribution of the vesicle membrane. Here, we also address limitations in the field and point to future fundamental and applied research in the area.

Combination chemotherapy is a promising method of improving cancer treatment, but the distinct pharmacokinetics of combined drugs and non-specific drug distribution slow down the development in the clinic. In this study, folate (FA) receptor-targeted polymersomes with apparent bilayered lamellar structure were successfully developed to co-encapsulate a hydrophobic-hydrophilic chemotherapeutic drug pair (PTX and DOX) in a single vesicle for enhancing the combination chemotherapeutic effect. Hydrophobic PTX was loaded into the thick hydrophobic lamellar membrane by the self-assembly of triblock copolymer PCL8000-PEG8000-PCL8000, while hydrophilic DOX was encapsulated into the hydrophilic reservoir using a trans-membrane ammonium sulfate gradient method. In vitro release study indicated that the drugs were released from the polymersomes in a controlled and sustained manner. Cellular uptake study indicated that FA-targeted Co-PS had higher internalization efficiency in FA receptor-overexpressing BEL-7404 cells than non-targeted Co-PS. In vitro cytotoxicity assay demonstrated that FA-targeted Co-PS exhibited less cytotoxic effect than free drug cocktail, but suppressed the growth of tumor cells more efficiently than non-targeted Co-PS. Ex vivo imaging biodistribution studies revealed that FA-targeted Co-PS led to highly efficient targeting and accumulation in the BEL-7404 xenograft tumor. Furthermore, the in vivo antitumor study showed that the combination chemotherapy of polymersomes to BEL-7404 tumor via intravenous injection was superior to free drug cocktail treatment, and the FA-targeted Co-PS exhibited significantly higher tumor growth inhibition than non-targeted Co-PS group. Therefore, the newly developed FA-targeted co-delivery polymersomes hold great promise for simultaneous delivery of multiple chemotherapeutics and would have great potential in tumor-targeting and combination chemotherapy. Statement of Significance Combination chemotherapy is a promising method of improving cancer treatment, but the distinct pharmacokinetics of combined drugs and non-specific drug distribution slow down the development in the clinic. In our study, novel folate-targeted co-delivery polymersomes (Co-PS) were successfully developed to encapsulate a hydrophobic-hydrophilic chemotherapeutic drug pair (paclitaxel and doxorubicin) into the different compartments of the vesicle. In vivo studies revealed that the combination chemotherapy of polymersomes to BEL-7404 xenograft tumor via intravenous injection was superior to free drug cocktail treatment, and the FA-targeted Co-PS exhibited significantly higher tumor growth inhibition than non-targeted Co-PS group. Therefore, the newly developed FA-targeted co-delivery polymersomes hold great promise for simultaneous delivery of multiple chemotherapeutics and would have great potential in tumor-targeting and combination chemotherapy.

A ligand decorated, synthetic polypeptide block copolymer platform with environment-responsive capabilities was designed. We evaluated the potential of this system to function as a polymersome for targeted-delivery of a systemic chemotherapy to tumors. Our system employed click chemistry to provide a pH-responsive polypeptide block that drives nanoparticle assembly, and a ligand (folic acid) conjugated PEG block that targets folate-receptor over-expressing cancer cells. These nanocarriers were found to encapsulate a high loading of conventional chemotherapeutics (e.g. doxorubicin at physiological pH) and release the active therapeutic at lysosomal pH upon cellular uptake. The presence of folic acid on the nanoparticle surface facilitated their active accumulation in folate-receptor-overexpressing cancer cells (KB), compared to untargeted carriers. Folate-targeted nanoparticles loaded with doxorubicin also showed enhanced tumor accumulation in folate-receptor positive KB xenografts, resulting in the suppression of tumor growth in an in vivo hind flank xenograft mouse model.

Self-assembly schemes provide a simple and tunable approach to creating a myriad of well-defined nanostructures from design of macromolecules in bulk, thin film and solution environments. Here we demonstrated a facile method to construction of tetraphenylethylene nanoparticles (TPE NPs) by decomposition-assembly from pH-responsive and AIE-characteristic vesicles, which were self-assembled by an amphiphilic PEG 750 -POSS-(TPE) 7 polymer in aqueous solutions. The introduction of Schiff base bonds furnished the fluorescent polymersomes with unique pH responsiveness that is stable under physiological conditions but quickly degradable in acidic environments. Interestingly, the luminous vesicles were transformed into spherical TPE NPs in a solution of lower pH on account of the synergetic combination of cleavage rate of the Schiff base bonds and guidance effect of the entangled tadpole-shaped polymeric chains. The AIE feature of TPE molecule was completely retained in the TPE NPs. Compared to the pH-responsive PEG 750 -POSS-(TPE) 7 vesicles, these AIE-active TPE NPs possessed stable morphology and adjustable size by manipulation of the incubation time. These TPE NPs can be quickly internalized into the tumors through endocytosis pathway and retain strong blue luminescence inside the living cells for a long period, presenting the good photostability and biological imaging property. Cytotoxicity assay revealed that TPE NPs were biocompatible and thus can be utilized for long-term live cell imaging and biomedical applications.

The application of photodynamic therapy (PDT) in deep tissue has been severely restricted by the poor photosensitizers loading and tissue-penetration of visible light for exciting the photosensitizers. How to prepare a nanocarrier with high drug loading amount and remote controllability still remains the challenge. In this article, a novel drug delivery system nanodumbbell was designed. The nanodumbbell was assembled from the hydrophobic upconverting nanoparticle (UCN) core and hydrophilic polymersome shell. The "nanodumbbell" offers possibilities to overcome the problem mentioned above. The UCN core works as a transducer to convert deeply penetrating near-infrared light to visible light to activate photosensitizers zinc (II) phthalocyanine (ZnPc) for photodynamic therapy. The polymersome lipid shell is used for loading ZnPc and protecting the whole system from nonspecific absorbance or corrosion during the transportation. The nanodumbbell is appealing because it can simultaneously achieve the high loading amount of ZnPc while avoiding UCNs aggregation. The reactive oxygen species (ROS) production test and PDT test in vitro suggested that the fluorescence emitted from the UCNs can be effectively transferred to the photosensitizers to produce cytotoxic ROS. When the UCN@lipid@polymersome nanodumbbell was decorated with targeting peptide (RGD), it presented better target specificity to cells. Our data suggest that this nanoparticle may serve as a useful nanoplatform for PDT treatment in deep-cancer therapy based on upconverting mechanism.

The topical application of enzymes for UV-induced damage repair, such as catalase, represents an interesting strategy for "active" photoprotection. However, catalase, a large and hydrophilic molecule, needs to penetrate the skin to present activity and, in this sense, nanocarriers can provide an aid for barrier crossing. Among the nanocarriers, polymersomes (Ps) obtained by the self-aggregation of amphiphilic block copolymers represent an alternative for topical enzyme delivery. Here, catalase-loaded Ps of Pluronic® L121, an amphiphilic triblock copolymer, were prepared by direct dissolution and in vitro evaluated regarding safety and efficacy. The Ps presented a suitable photo/cytotoxicity profile regarding the sun-damaged epidermis. Pre-clinical safety tests indicated that the HET-CAM assay was more appropriate than cytotoxicity assays to predict the irritant potential of the Ps. Based on cutaneous permeation assays associated with laser scanning confocal fluorescence microscopy, the Ps increased ten times the catalase percentage of skin permeation. Additionally, in vitro assays indicated that catalase-loaded Ps were able to eliminate UV-induced lipid peroxidation in deeper layers of the skin (viable epidermis + dermis) in comparison to free catalase. Penetration assays in 3D cell culture and efficacy assays confirmed the preferential delivery of catalase in the deeper layers of the skin owing to the permeation enhancer effect of Pluronic L121 and/or the membrane translocation capacity of the Ps. In conclusion, our findings indicate catalase-loaded Ps as an innovative nanomaterial for active sunscreens.

International audience; In this article, is reported for the first time the preparation of nanoparticles from graft copolymer composed of a hydrophilic backbone made of poly(2-methyl-2-oxazoline-co-2-pentyl-2-oxazoline) and hydrophobic poly(d,l-lactide) grafts. The copolymers were synthesized by the grafting-onto approach through the Huisgen 1,3-dipolar cycloaddition reaction. The success of the reaction was confirmed by H-1 NMR, FTIR and thermogravimetric analysis (TGA). Different copolymers were prepared from two molecular weight backbones (5.7 x 10(3) and 14.2 x 10(3) g mo1(-1)) giving graft copolymers with molecular weight in the range of 3.7 x 10(4) to 113 x 10(4) g mo1(-1). These copolymers self-assembled to form nanoparticles in water. Nanoparticles of spherical shape and various morphologies, going from polymersomes to core-shell and homogenous spherical nano-objects, were imaged by cryo-transmission electron microscopy (cryo-TEM) and analyzed by dynamic light scattering (DLS) and small -angle neutron scattering (SANS)

Challenges regarding the synthesis, purification, and characterization of the amphiphilic triblock copolymer poly(2-methyl-2-oxazoline)-block-polydimethylsiloxane-block-poly(2-methyl-2-oxazoline) (PMOXA-b-PDMS-b-PMOXA) are herein illustrated and discussed. A block copolymer (BCP) library was synthesised by cationic ring-opening polymerisation of 2-methyl-2-oxazoline on broadly and narrowly dispersed PDMS macroinitiators. The crude BCPs were fractioned by a newly developed cosolvent fractionation technique. With this it is possible to remove the side products of chain-transfer reactions, intrinsic to the polymerisation of 2-oxazolines. The obtained fractions were characterized by nuclear magnetic resonance, gel permeation chromatography and light scattering, revealing that the cosolvent fractionation separates multiblock copolymers from triblock copolymers. Self-assembly of the individual polymer fractions showed that the cosolvent fractionation is essential to yield polymersome forming triblock copolymers.

Vancomycin (VM), a last resort to control methicillin-resistant S. aureus (MRSA) infections, is on the verge of becoming ineffective. Novel nano delivery systems of VM have the potential to combat MRSA. The search for novel materials for nanoantibiotic development is therefore an active research area. In this study, oleic acid (OA) was coupled with monomethoxy polyethylene glycol (mPEG) to obtain a novel bio-safe amphiphilic polymer, mPEG-OA. The critical micelle concentration of mPEG-OA, was found to be 4.5×10-8m/L. VM-loaded polymersomes were prepared from mPEG-OA and evaluated for size, polydispersity index (PDI), zeta potential (ZP), surface morphology, drug release, in vitro and in vivo antibacterial activity. The size, PDI and ZP of VM-loaded polymersomes were 142.9±7.5nm, 0.228±0.03 and -18.3±3.55mV respectively. Transmission electron microscopy images revealed the spherical shape of polymersomes. The encapsulation efficiency was 53.64±1.86%. The drug release from polymersomes was sustained and in vitro antibacterial activity was 42- and 5-fold more against S. aureus and MRSA, compared with plain VM. An in vivo BALB/c mice, skin infection models revealed that treatment with VM-loaded polymersomes significantly reduced the MRSA burden compared with plain VM and blank polymersomes. There was a 183 and a 25-fold reduction in the MRSA colony finding units load in mice skin treated with VM-loaded polymersomes compared to that treated with blank polymersomes and bare VM respectively. In summary, the developed VM-loaded polymersomes from novel mPEG-OA polymer were found to be a promising nanoantibiotic against MRSA.