Magnetic DNA Vector Constructed from PDMAEMA Polycation and PEGylated Brush-Type Polyanion with Cross-Linkable Shell

A novel magnetic-responsive complex composed of polycation, DNA, and polyanion has been constructed via electrostatic interaction. The magnetic nanoparticles (MNPs) were first coated with a polycation, poly­[2-(dimethylamino)­ethyl methacrylate] end-capped with cholesterol moiety (Chol-PDMAEMA₃₀), and then binded with DNA through electrostatic interaction; the complexes were further interacted with the brush-type polyanion, namely poly­[poly­(ethylene glycol)­methyl ether methacrylate]-<i>block</i>-poly­[methacrylic acid carrying partial mercapto groups] (PPEGMA-<i>b</i>-PMAA_SH). The resulting magnetic particle/DNA/polyion complexes could be stabilized by oxidizing the mercapto groups to form cross-linking shell with bridging disulfide (S–S) between PPEGMA-<i>b</i>-PMAA_SH molecular chains. The interactions among DNA, Chol-PDMAEMA coated MNPs, and PPEGMA-<i>b</i>-PMAA_SH were studied by agarose gel retardation assay. The complexes were fully characterized by means of zeta potential, transmission electron microscopy (TEM), dynamic light scattering (DLS) measurements, cytotoxicity assay, antinonspecific protein adsorption, and <i>in vitro</i> transfection tests. All these results indicate that this kind of magnetic-responsive complex has potential applications for gene vector

Polyphosphoester-Camptothecin Prodrug with Reduction-Response Prepared via Michael Addition Polymerization and Click Reaction

Polyphosphoesters (PPEs), as potential candidates for biocompatible and biodegradable polymers, play an important role in material science. Various synthetic methods have been employed in the preparation of PPEs such as polycondensation, polyaddition, ring-opening polymerization, and olefin metathesis polymerization. In this study, a series of linear PPEs has been prepared via one-step Michael addition polymerization. Subsequently, camptothecin (CPT) derivatives containing disulfide bonds and azido groups were linked onto the side chain of the PPE through Cu­(I)-catalyzed azidealkyne cyclo-addition “click” chemistry to yield a reduction-responsive polymeric prodrug P­(EAEP-PPA)-<i>g</i>-<i>ss</i>-CPT. The chemical structures were characterized by nuclear magnetic resonance spectroscopy, gel permeation chromatography, Fourier transform infrared, ultraviolet–visible spectrophotometer, and high performance liquid chromatograph analyses, respectively. The amphiphilic prodrug could self-assemble into micelles in aqueous solution. The average particle size and morphology of the prodrug micelles were measured by dynamic light scattering and transmission electron microscopy, respectively. The results of size change under different conditions indicate that the micelles possess a favorable stability in physiological conditions and can be degraded in reductive medium. Moreover, the studies of in vitro drug release behavior confirm the reduction-responsive degradation of the prodrug micelles. A methyl thiazolyl tetrazolium assay verifies the good biocompatibility of P­(EAEP-PPA) not only for normal cells, but also for tumor cells. The results of cytotoxicity and the intracellular uptake about prodrug micelles further demonstrate that the prodrug micelles can efficiently release CPT into 4T1 or HepG2 cells to inhibit the cell proliferation. All these results show that the polyphosphoester-based prodrug can be used for triggered drug delivery system in cancer treatment

Folate-Conjugated Polyphosphoester with Reversible Cross-Linkage and Reduction Sensitivity for Drug Delivery

To improve the therapeutic efficacy and circulation stability in vivo, we synthesized a new kind of drug delivery carrier based on folic acid conjugated polyphosphoester via the combined reactions of Michael addition polymerization and esterification. The produced amphiphilic polymer, abbreviated as P­(EAEP-AP)-LA-FA, could self-assemble into nanoparticles (NPs) with core-shell structure in water and reversible core cross-linked by lipoyl groups. Using the core cross-linked FA-conjugated nanoparticles (CCL-FA NPs) to encapsulate hydrophobic anticancer drug doxorubicin (DOX), we studied the stability of NPs, in vitro drug release, cellular uptake, and targeting intracellular release compared with both un-cross-linked FA-conjugated nanoparticles (UCL-FA NPs) and core cross-linked nanoparticles without FA conjugation (CCL NPs). The results showed that under the condition of pH 7.4, the DOX-loaded CCL-FA NPs could maintain stable over 72 h, and only a little DOX release (∼15%) was observed. However, under the reductive condition (pH 7.4 containing 10 mM GSH), the disulfide-cross-linked core would be broken up and resulted in 90% of DOX release at the same incubation period. The study of methyl thiazolyl tetrazolium (MTT) assay indicated that the DOX-loaded CCL-FA NPs exhibited higher cytotoxicity (IC₅₀: 0.33 mg L^–1) against HeLa cells than the DOX-loaded CCL NPs without FA. These results indicate that the core cross-linked FA-conjugated nanoparticles have unique stability and targetability

One-Pot Synthesis of pH/Redox Responsive Polymeric Prodrug and Fabrication of Shell Cross-Linked Prodrug Micelles for Antitumor Drug Transportation

Shell cross-linked (SCL) polymeric prodrug micelles have the advantages of good blood circulation stability and high drug content. Herein, we report on a new kind of pH/redox responsive dynamic covalent SCL micelle, which was fabricated by self-assembly of a multifunctional polymeric prodrug. At first, a macroinitiator PBYP-<i>ss</i>-<i>i</i>BuBr was prepared via ring-opening polymerization (ROP), wherein PBYP represents poly­[2-(but-3-yn-1-yloxy)-2-oxo-1,3,2-dioxaphospholane]. Subsequently, PBYP-<i>hyd</i>-DOX-<i>ss</i>-P­(DMAEMA-<i>co</i>-FBEMA) prodrug was synthesized by a one-pot method with a combination of atom transfer radical polymerization (ATRP) and a Cu­(I)-catalyzed azide–alkyne cycloaddition (CuAAC) reaction using a doxorubicin (DOX) derivative containing an azide group to react with the alkynyl group of the side chain in the PBYP block, while DMAEMA and FBEMA are the abbriviations of <i>N</i>,<i>N</i>-(2-dimethylamino)­ethyl methacrylate and 2-(4-formylbenzoyloxy)­ethyl methacrylate, respectively. The chemical structures of the polymer precursors and the prodrugs have been fully characterized. The SCL prodrug micelles were obtained by self-assembly of the prodrug and adding cross-linker dithiol bis­(propanoic dihydrazide) (DTP). Compared with the shell un-cross-linked prodrug micelles, the SCL prodrug micelles can enhance the stability and prevent the drug from leaking in the body during blood circulation. The average size and morphology of the SCL prodrug micelles were measured by dynamic light scattering (DLS) and transmission electron microscopy (TEM), respectively. The SCL micelles can be dissociated under a moderately acidic and/or reductive microenvironment, that is, endosomal/lysosomal pH medium or high GSH level in the tumorous cytosol. The results of DOX release also confirmed that the SCL prodrug micelles possessed pH/reduction responsive properties. Cytotoxicity and cellular uptake analyses further revealed that the SCL prodrug micelles could be rapidly internalized into tumor cells through endocytosis and efficiently release DOX into the HeLa and HepG2 cells, which could efficiently inhibit the cell proliferation. This study provides a fast and precise synthesis method for preparing multifunctional polymer prodrugs, which hold great potential for optimal antitumor therapy

Synthesis of PEGylated Ferrocene Nanoconjugates as the Radiosensitizer of Cancer Cells

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

Additional file 1 of METTL3 promotes osteoblast ribosome biogenesis and alleviates periodontitis

Additional file 1: Figure S1. The effect of METTL3 on the rRNA stability. A The rRNA expression in METTL3-kncokdown cells after treating with 5 μg/mL ActD for 0–8 h was measured by qRT-PCR. n = 3. Figure S2. A, B The level of ROS was measured after METTL3 knockdown. n = 3. All data represent the mean ± SD. Figure S3. The effect of METTL3 knockdown on nucleolus, mTOR-Akt, and p53 pathway. A, B The nucleolar morphology of osteoblasts under LPS and osteogenic induction 3 days was assessed by immunocytochemistry. 20 nM actinomycin D (ActD) was the positive control of nucleolar stress. C The nucleolar number was detected by AgNOR staining. D, E The activation of p53 and AKT-mTOR signaling were examined by western blotting. *P < 0.05; **P < 0.01; ***P < 0.001. Figure S4. The effect of CHIR on the expression of Dkk3 and Sostdc1 in METTL3 knockdown cells. A, B The shCTRL and shMETTL3 cells were stimulated by LPS and osteogenic induction medium with or without CHIR. The mRNA expression of Dkk3 and Sostdc1 was detected by RT-qPCR. n = 3. All data represent the mean ± SD. *P < 0.05; ***P < 0.001. Figure S5. The effect of SAH and CHIR in periodontitis mice. A The proteins were evaluated in LPS-stimulated cells after stimulating with 5 μM SAH and 3 μM CHIR for 3 days. B Masson staining images of the periodontium. All data represent the mean ± SD. *P < 0.05; **P < 0.01. Table S1. Primer sequences for qRT-PCR. Table S2. Polysome profiling buffer

Janus [3:5] Polystyrene–Polydimethylsiloxane Star Polymers with a Cubic Core

We describe the precision synthesis and self-assembly of a series of Janus star polymers with mixed [3:5] heteroarms of polystyrene (PS) and polydimethyl­siloxane (PDMS) precisely arranged on a cubic scaffold of T₈ polyhedral oligomeric silsesquioxane (POSS) in a spatially segregated fashion. The synthesis begins with a Janus POSS compound with three 2-hydroxylethyl groups on one face and five vinyl pendant groups on the rest vertexes. Facilitated by esterification and a “click” adaptor, two types of polymer arms are attached efficiently by sequential “click” reactions, which constitutes a general approach for modular synthesis of such Janus star polymers. The Janus feature is thoroughly characterized using NMR, FT-IR, SEC, and MALDI-TOF mass spectrometry, and the self-assembled structures are studied by small-angle X-ray scattering (SAXS) experiments. With increasing molecular weight of PS arm, the self-assembled phase transits from lamellae (LAM) to hexagonally packed cylinder (HEX) and further to inversed HEX structure, even though the molecular weight of each PDMS arm is as small as 1.4 kDa. Correspondingly, the feature sizes of these samples are very small. For example, the intercolumnar distance is only ∼6.4 nm in the HEX phase, and the column radius is as small as 1.8 nm. It is anticipated that diverse nanostructures can be created from the self-assembly of these Janus star polymers

Rapid and Efficient Anionic Synthesis of Well-Defined Eight-Arm Star Polymers Using OctavinylPOSS and Poly(styryl)lithium

A new approach has been developed for the preparation of well-defined, eight-arm star polymers via the addition of poly­(styryl)lithium to octavinylPOSS in benzene. The reaction proceeds rapidly to completion (within 5 min for molecular weight of each arm up to 33 kg/mol), forming predominantly eight-arm star polymers. The products were purified by fractionation and fully characterized by ¹H NMR, ¹³C NMR, ²⁹Si NMR, FT-IR, MALDI-TOF mass spectrometry, and size exclusion chromatography. Compared to conventional coupling approaches, this process is found to be less sensitive to the stoichiometry of the reactants and the molecular weight of each arm. A mechanism based on cross-association and intra-aggregate addition is invoked to account for this unusual observation. As evidence, when a polar solvent, tetrahydrofuran, or a strongly coordinating and disassociating Lewis base, tetramethylethylenediamine, was used to dissociate the living polymer chains, star polymers with lower average arm numbers than those of the products synthesized in pure benzene were formed at the same stoichiometry of the reactants. The method has general implications in the understanding of the reactive nature of the living anionic polymerization and may find practical application in the synthesis of functional star polymers of diverse compositions and architectures

Injectable and Degradable POSS–Polyphosphate–Polysaccharide Hybrid Hydrogel Scaffold for Cartilage Regeneration

The limited self-repair capacity of articular cartilage has motivated the development of stem cell therapy based on artificial scaffolds that mimic the extracellular matrix (ECM) of cartilage tissue. In view of the specificity of articular cartilage, desirable tissue adhesiveness and stable mechanical properties under cyclic mechanical loads are critical for cartilage scaffolds. Herein, we developed an injectable and degradable organic–inorganic hybrid hydrogel as a cartilage scaffold based on polyhedral oligomeric silsesquioxane (POSS)-cored polyphosphate and polysaccharide. Specifically, acrylated 8-arm star-shaped POSS-poly(ethyl ethylene phosphate) (POSS-8PEEP-AC) was synthesized and cross-linked with thiolated hyaluronic acid (HA-SH) to form a degradable POSS-PEEP/HA hydrogel. Incorporation of POSS in the hydrogel increased the mechanical properties. The POSS-PEEP/HA hydrogel showed enzymatic biodegradability and favorable biocompatibility, supporting the growth and differentiation of human mesenchymal stem cells (hMSCs). The chondrogenic differentiation of encapsulated hMSCs was promoted by loading transforming growth factor-β3 (TGF-β3) in the hydrogel. In addition, the injectable POSS-PEEP/HA hydrogel was capable of adhering to rat cartilage tissue and resisting cyclic compression. Furthermore, in vivo results revealed that the transplanted hMSCs encapsulated in the POSS-PEEP/HA hydrogel scaffold significantly improved cartilage regeneration in rats, while the conjugation of TGF-β3 achieved a better therapeutic effect. The present work demonstrated the potential of the injectable, biodegradable, and mechanically enhanced POSS-PEEP/HA hybrid hydrogel as a scaffold biomaterial for cartilage regeneration

Influence of Regio-Configuration on the Phase Diagrams of Double-Chain Giant Surfactants

It has been established that a minute difference of the primary chemical and topological structures influences the self-assembly behaviors of giant surfactants; however, the regio-configuration effect has been rarely reported. Herein, we report a systematic study on the self-assembly behaviors of a series of double-chain giant surfactant regio-isomers, which consist of a hydrophilic polyhedral oligomeric silsesquioxane (POSS) head and two identical hydrophobic polystyrene (PS) tails with various molecular weights tethered in <i>para</i>-, <i>meta</i>-, and <i>ortho</i>-configurations, respectively. Small-angle X-ray scattering and transmission electron microscopy characterizations have been combined to investigate the phase behaviors of each sample and construct the phase diagrams for the three isomers with respect to the molecular weights of PS tails. It is observed that the regio-configuration significantly impacts the self-assembly behaviors of the giant surfactant isomers, including order-to-disorder (ODT) and order-to-order (OOT) transitions. In each isomer system, the order-to-disorder transition temperature (<i>T</i>_ODT) changes nonmonotonically with the length of PS tails, which is generally similar to the variation of <i>T</i>_ODT for block copolymers but also exhibits some peculiar features associated with the rigid conformation of headgroup. With equal length of PS tails, <i>T</i>_ODT of the three isomers is in the descending order of <i>ortho</i> > <i>meta</i> > <i>para</i>. There is a pronounced and systematic phase boundary shift to lower volume fraction of PS (<i>f</i>_PS) and to lower temperatures from <i>para</i> to <i>meta</i> to <i>ortho</i>. This is closely related to the compounds’ regio-configuration and rigid 3D conformation of the headgroup and may be understood through the lower effective <i>f</i>_PS as two tails get further apart. These findings elucidate the sophisticated effect of the regio-configuration on self-assembly behaviors. It suggests regio-configuration as an additional factor in tuning the self-assembly of giant surfactants at sub-10 nm or even sub-5 nm length scales, which is of significant technical importance