Graft copolymers have unique application scenarios in the field of high-performance thermoplastic elastomers, resins and rubbers. β-myrcene (My) is a biomass monomer derived from renewable plant ...resources, and its homopolymer has a low glass transition temperature and high elasticity. In this work, a series of tapered copolymers P(My-
-AMS)
(k = 1, 2, 3) were first synthesized in cyclohexane by one-pot anionic polymerization of My and α-methyl styrene (AMS) using sec-BuLi as the initiator. PAMS chain would fracture when heated at high temperature and could endow the copolymer with thermal degradation property. The effect of the incorporation of AMS unit on the thermal stability and glass transition temperature of polymyrcene main chain was studied. Subsequently, the double bonds in the linear copolymers were partially epoxidized and hydroxylated into hydroxyl groups to obtain hydroxylated copolymer, which was finally used to initiate the ring-opening polymerization (ROP) of ε-caprolactone (ε-CL) to synthesize the graft copolymer with PCL as the side chain. All these copolymers before and after modifications were characterized by proton nuclear magnetic resonance (
H NMR), gel permeation chromatography (GPC), thermogravimetry analysis (TGA), and differential scanning calorimeter (DSC).
The acid-cleavable amphiphilic prodrug DOX-PEG-DOX self-assemble to form nanoparticles and enter the cell by endocytosis for the pH-triggered intracellular delivery of DOX.
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PEGylated ...prodrug, covalent attaching polyethylene glycol (PEG) polymer chains to therapeutic drugs, is one of the most promising techniques to improve the water-solubility, stability, and therapeutic effect of drugs. In this study, three PEGylated acid-sensitive prodrugs DOX-PEG-DOX with different molecular weights, were prepared via Schiff-base reaction between aldehyde-modified PEG and the amino groups of doxorubicin (DOX). This kind of amphiphilic polymeric prodrug could be self-assemble into nanoparticles in aqueous solution. The average particle size and morphologies of the prodrug nanoparticles under different pH conditions were observed by dynamic light scattering (DLS) and transmission electron microscopy (TEM), respectively. It turned out that the nanoparticles could be kept stable in the physiological environment, but degraded in acidic medium. Subsequently, we also investigated in vitro drug release behavior and found that the prodrug had acid-sensitive property. The cytotoxicity and intracellular uptake assays revealed that the prodrugs could rapidly internalized by HeLa or HepG2 cells to release DOX and effectively inhibited the proliferation of the tumor cells, which have the potential for use in cancer therapy.
Frank–Kasper (F-K) and quasicrystal phases were originally identified in metal alloys and only sporadically reported in soft materials. These unconventional sphere-packing schemes open up ...possibilities to design materials with different properties. The challenge in soft materials is how to correlate complex phases built from spheres with the tunable parameters of chemical composition and molecular architecture. Here, we report a complete sequence of various highly ordered mesophases by the self-assembly of specifically designed and synthesized giant surfactants, which are conjugates of hydrophilic polyhedral oligomeric silsesquioxane cages tethered with hydrophobic polystyrene tails. We show that the occurrence of these mesophases results from nanophase separation between the heads and tails and thus is critically dependent on molecular geometry. Variations in molecular geometry achieved by changing the number of tails from one to four not only shift compositional phase boundaries but also stabilize F-K and quasicrystal phases in regions where simple phases of spheroidal micelles are typically observed. These complex self-assembled nanostructures have been identified by combining X-ray scattering techniques and real-space electron microscopy images. Brownian dynamics simulations based on a simplified molecular model confirm the architecture-induced sequence of phases. Our results demonstrate the critical role of molecular architecture in dictating the formation of supramolecular crystals with “soft” spheroidal motifs and provide guidelines to the design of unconventional self-assembled nanostructures.
Radiation is one of the most widely used methods for cancer diagnosis and therapy. Herein, we report a new type of radiation sensitizer (Fc-PEG) by a facile one-step reaction of conjugating the ...hydrophilic PEG chain with hydrophobic ferrocene molecule. The chemical composition and structure of Fc-PEG have been thoroughly characterized by FT-IR, NMR, GPC, and MALDI-TOF mass spectrometry. This Fc-PEG conjugate could self-assemble in aqueous solution into spherical aggregates, and it was found that the exposure to 4 Gy of X-ray radiation have little influence on the shape and size of these aggregates. After the chemical bonding with PEG chains, the uptake level of Fe element could be enhanced via the formation of aggregates. The live/dead, CCK-8, as well as apoptosis assays, indicated that the death of cancer cells can be obviously increased by X-ray radiation after the incubation of these Fc-based nanoconjugates, which might be served as the radiation sensitizer toward cancer cells. We suggest that this radiosensitizing effect comes from the enhancement of reactive oxygen specimen (ROS) level as denoted by both flow cytometric and fluorescence microscopic analysis. The enhanced radiation sensitivity of cancer cells is contributed by the synergic effect of Fe-induced radiation-sensitizing and the increased uptake of nanoconjugates after polymeric grafting.
Novel pH- and temperature-responsive double-hydrophilic diblock copolymers, poly(ethylethylene phosphate)-block-poly2-(dimethylamino)ethyl methacrylate (PEEP-b-PDMAEMA), have been synthesized via the ...combination of ring-opening polymerization (ROP) and atom transfer radical polymerization (ATRP). The PEEP block with a bromine-terminated end (PEEP-Br) was first prepared by ROP of 2-ethoxy-2-oxo-1,3,2-dioxaphospholane (EEP) using 2-hydroxyethyl 2-bromoisobutyrate as a bifunctional initiator and stannous octoate as a catalyst. ATRP was then used to polymerize DMAEMA monomer in a methanol/water mixture with PEEP-Br as a macroinitiator, resulting in diblock copolymers of PEEP-b-PDMAEMA. Their chemical structures were respectively characterized by 1H NMR, 13C NMR, 31P NMR, and FT-IR. Their molar mass distributions were determined by gel permeation chromatography (GPC). The critical aggregation concentration (cac) of PEEP-b-PDMAEMA in aqueous solution, which was measured by the fluorescence probe technique, depends on the block composition. The results measured by static laser light scattering (LLS), dynamic light scattering (DLS), and transmission electron microscopy (TEM) reveal that these diblock copolymers are able to self-assemble into aggregates with different particle sizes and morphologies in aqueous solutions, depending on various pH media. On the other hand, the UV−vis measurement shows that these diblock copolymers exhibit a reproducible temperature-responsive behavior with a lower critical solution temperature (LCST) that is tunable by the block composition and pH. In addition, agarose gel retardation assays, TEM, and zeta potential measurements demonstrate that such double-hydrophilic diblock copolymers can effectively condense DNA, potentially useful for the gene delivery.
In this paper, SiO2 nanoparticles were first modified with (heptadecafluoro-1, 1, 2, 2-tetradecyl)trimethoxysilane (TSL-8233) to improve its dispersibility and compatibility in the polymer matrix. ...The structure and property of SiO2 nanoparticles before and after modification were characterized by FT-IR, TGA and TEM analysis. Together with poly(vinylidene fluoride-co-hexafluoropropylene) (PVdF-HFP) and polypropylene (PP) nonwoven fabric, these SiO2 nanoparticles were then used to construct two kinds of composite separators (abbreviated as PHS for pristine SiO2 and PHS-8233 for modified TSL-8233@SiO2). The morphology, electrolyte uptake, ionic conductivity and electrochemical properties of the composite separators were analyzed by SEM analysis, AC impedance measurements, charge–discharge cycle and C-rate tests, respectively. These results indicated that PHS-8233 composite separator exhibited an improved pore distribution, electrolyte uptake (280wt%) and ionic conductivity (1.90mScm−1). Even more importantly, LiFePO4/Li cells assembled with PHS-8233 composite separator displayed remarkable C-rate performance, which showed an enhancement in the chemical stability and discharge capacity. The capacity kept above 144mAhg−1 after 100 charge–discharge cycles.
•Fluorinated SiO2 nanoparticles showed better dispersibility and compatibility.•The composite separator exhibited improved physical and electrochemical properties.•The discharge capacity of cells kept about 144mAhg−1 after 100 cycles.
A vector tabu search algorithm encapsulating a new updating mechanism for current states and a directed search phase is proposed to enhance its searching ability for Pareto-optimal solutions. The new ...updating mechanism considers quantitatively both the number of improved objectives and the amount of improvements in a specified objective, of multiobjective design problems. The directed search phase uses some desired directions, a priori knowledge about the objective space, as the moving direction to efficiently find improved solutions without any gradient computation procedure. The numerical results on both high- and low-frequency inverse problems are reported to demonstrate the pros and cons of the proposed algorithm. It is observed that the proposed vector tabu search method outperforms its ancestors in both the convergence performance and the solution quality.
A series of parent block copolyesters poly(ɛ-caprolactone)-block-poly2-(2-oxo-1, 3, 2-dioxaphospholoyloxy)ethyl acrylate (PCL-b-POPEA) with different block lengths have been synthesized by ...ring-opening polymerization (ROP) and four kinds of mercaptans were then used in the postpolymerization modification via Michael-type addition reaction, resulting in several block copolyesters with various functionalities (e.g., hydroxyl, carboxyl, amine, and amino acid) in their pendant groups. The chemical structures of these block copolymers were characterized by FT-IR, NMR spectroscopy and GPC analysis. The self-assembly behaviors of PCL-b-POPEA have been studied by fluorescence probe technique, transmission electron microscopy (TEM) and high-performance particle size (HPPS) instrument. In vitro cytotoxicity test indicated that the block copolymers possess good biocompatibility. Initial in vitro drug loading and release studies using Doxorubicin (DOX) as a model drug demonstrated a faster release in the presence of phosphodiesterase I as compared to the system without enzyme. Moreover, it was found that DOX-loaded nanoparticles displayed higher inhibition to KB cell proliferation in comparison with free DOX. Therefore, the combination of ROP and Michael-type addition reaction provides a general access to various types of multifunctional and biodegradable materials.
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Giant surfactants refer to a new kind of amphiphile by incorporating functional molecular nanoparticles with polymer tails. As a size-amplified counterpart of small-molecule surfactants, they serve ...to bridge the gap between small-molecule surfactants and amphiphilic block copolymers. This work reports the design and synthesis of single-tailed giant surfactants carrying a hydrophobic poly(ε-caprolactone) (PCL) as the tail and a hydrophilic cage-like polyhedral oligomeric silsesquioxane (POSS) nanoparticle as the head. The modular synthetic strategy features an efficient "growing-from" and "click-modification" approach. Starting from a monohydroxyl and heptavinyl substituted POSS (VPOSS-OH), a PCL chain with controlled molecular weight and narrow polydispersity was first grown by the ring-opening polymerization (ROP) of ε-CL under the catalysis of stannous octoate, leading to a PCL chain end-capped with heptavinyl substituted POSS (VPOSS-PCL). To endow the POSS head with adjustable polarity and functionality, three kinds of hydrophilic groups, including hydroxyl groups, carboxylic acids, and amine groups, were installed to the periphery of POSS molecule by a high-efficiency thiol-ene "click" reaction. The compounds were fully characterized by NMR, gel permeation chromatography (GPC), MALDI-TOF mass spectrometry, and TGA analysis. In addition, the preliminary self-assembly study of these giant surfactants was also investigated by TEM and dynamic laser light scattering (DLS), which indicated that they can form spherical nanoparticles with different diameters in aqueous solution. This work affords a straightforward and versatile way for synthesizing single-tailed giant surfactants with diverse head surface functionalities.
Tumor-associated macrophages (TAMs)-based immunotherapy is a promising strategy. Since TAMs are mainly composed of M2-type macrophages, they have a promoting effect on tumor growth, invasion, and ...metastasis. M2-type macrophages contain a specific receptor CD163 on their surface, providing a prerequisite for active targeting to TAMs. In this study, we prepared CD163 monoclonal antibody modified doxorubicin-polymer prodrug nanoparticles (abbreviated as mAb-CD163-PDNPs) with pH responsiveness and targeted delivery. First, DOX was bonded with the aldehyde group of a copolymer by Schiff base reaction to form an amphiphilic polymer prodrug, which could self-assemble into nanoparticles in the aqueous solution. Then, mAb-CD163-PDNPs were generated through a "Click" reaction between the azide group on the surface of the prodrug nanoparticles and dibenzocyclocytyl-coupled CD163 monoclonal antibody (mAb-CD163-DBCO). The structure and assembly morphology of the prodrug and nanoparticles were characterized by
H NMR, MALDI-TOF MS, FT-IR UV-vis spectroscopy, and dynamic light scattering (DLS). In vitro drug release behavior, cytotoxicity, and cell uptake were also investigated. The results show that the prodrug nanoparticles have regular morphology and stable structure, especially mAb-CD163-PDNPs, which can actively target TAMs at tumor sites, respond to the acidic environment in tumor cells, and release drugs. While depleting TAMs, mAb-CD163-PDNPs can actively enrich drugs at the tumor site and have a strong inhibitory effect on TAMs and tumor cells. The result of the in vivo test also shows a good therapeutic effect, with a tumor inhibition rate of 81%. This strategy of delivering anticancer drugs in TAMs provides a new way to develop targeted drugs for immunotherapy of malignant tumors.
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