Rongcui Jiang

Monodispersed Brush-Like Conjugated Polyelectrolyte Nanoparticles with Efficient and Visualized SiRNA Delivery for Gene Silencing

RNA interference is supposed to be one of the most powerful technologies for suppression of genes and treatment of diverse human diseases while the safe delivery and visualization of siRNA were still challenging. In this text, a novel type of monodispersed conjugated polymer nanoparticles PFNBr with brush-like molecular structure was introduced into siRNA delivery system. The nanoparticles exhibited dual functions conveniently in the delivery system which can not only carry high amount of siRNA to penetrate intracellularly for knocking down targeted mRNA but also act as signal agents for siRNA tracking and cellular imaging. Due to the high density side chains with positive charges and more extended conformation of the spatial structure, PFNBr nanoparticles as nanocarrier for siRNA provided outstanding capture ability (1 mol polymer to more than 32.5 mol siRNA) and enhanced protection capability of siRNA molecules from degradation. Here, it should be noted that the concentration of carrier in the working platform was lowered from the level of μmol/L to nmol/L compared with other conjugated polymer delivery systems due to the outstanding carrying capacity of PFNBr. And meanwhile, this system acquired high gene silence efficiency and good biocompatibility. The proposed complex nanoparticles efficiently transfected siPlk1 into PANC-1 cells and induced high knockdown efficiency for targeted Plk1 mRNA to 23.9% and no significant cytotoxicity of the PFNBr/siRNA complexes was shown. Therefore, this working platform provides a solution to most of the common problems associated with the siRNA delivery, visualization, and therapeutic applications, and keeps a bright outlook for the development of new nucleic acid-based therapeutics and simultaneously for fluorescent bioimaging.

Engineering Lysosome-Targeting BODIPY Nanoparticles for Photoacoustic Imaging and Photodynamic Therapy under Near-Infrared Light

Developing lysosome-targeting organic nanoparticles combined with photoacoustic imaging (PAI) and photodynamic therapy (PDT) functions toward personalized medicine are highly desired yet challenging. Here, for the first time, lysosome-targeting BODIPY nanoparticles were engineered by encapsulating near-infrared (NIR) absorbed BODIPY dye within amphiphilic DSPE-mPEG5000 for high-performing lysosomal PAI and acid-activatable PDT against cancer cells under NIR light.

Homogeneous near-infrared emissive polymeric nanoparticles based on amphiphilic diblock copolymers with perylene diimide and PEG pendants: self-assembly behavior and cellular imaging application

An amphiphilic diblock copolymer, poly(perylene diimide acrylate)-block-poly(poly(ethyleneglycol)methacrylate) (PPDA-b-P(PEGMA)), has been synthesized via the reversible addition fragmentation transfer polymerization (RAFT) method. The polymer shows self-assembly behavior in water due to the synergistic effects of the strong hydrophobic interactions and π–π stacking of perylene diimide (PDI) groups. Homogeneous polymer nanoparticles (PNPs) in aqueous solution with good water solubility and stability were formed with an average size of 64.3 ± 3.3 nm, revealed by dynamic light scattering (DLS). The PNPs showed near-infrared (NIR) emission at 660 nm instead of the traditional emission of individual PDI groups at 530 nm. The aggregation-enhanced π–π stacking and the resulting NIR emission of the PDI groups were demonstrated by spectroscopy and 1H-NMR characterization. Cellular imaging of human pancreatic cancer cells was conducted with the obtained PNPs. Confocal microscopy results showed that the PNPs were located specifically within the cell cytoplasm. This study provides a new design concept to take full advantage of polymer amphipathy to fabricate nanoparticles with NIR emission for applications in bio-imaging.

Monodispersed grafted conjugated polyelectrolyte-stabilized magnetic nanoparticles as multifunctional platform for cellular imaging and drug delivery

An anionic grafted conjugated polyelectrolyte was synthesized, and then magnetic nanoparticles stabilized with this material were successfully prepared by a convenient method and used for bioimaging and drug delivery. Grafted conjugated polymer (PFPAA) containing abundant carboxyl groups was attached to the surface of Fe3O4 nanoparticles through ligand exchange with oleic acid and anionic grafted conjugated polyelectrolyte-stabilized magnetic nanoparticles (MNPs@PFPANa) were then obtained by ionization with sodium carbonate. These as-synthesized nanoparticles showed good water solubility and stability, with no precipitation observed in 8 months, and had a narrow size distribution with a mean hydrodynamic diameter of 26 ± 2.4 nm. In addition, these nanoparticles exhibited superparamagnetic properties with a saturation magnetization (Ms) of 20 emu g-1, which sufficient for bioapplications. Upon 48 h incubation with macrophage cells, the obtained nanoparticles showed good biocompatibility of 2 pg Fe per cell as measured by ICP-OES. Furthermore, MNPs@PFPANa were low toxicity as confirmed by an MTT assay using NIH-3T3 fibroblasts. Confocal microscopy results revealed that MNPs@PFPANa can be retained in cytoplasm with high fluorescence. MNPs@PFPANa exhibited good DOX drug loading efficiency of about 10 wt% and showed good therapeutic efficiency for BGC-823 cancer cells. These results indicated such multifunctional nanoparticles would be useful in bioimaging and as drug carriers for cancer treatment.

Cationic Conjugated Polymer/Fluoresceinamine-Hyaluronan Complex for Sensitive Fluorescence Detection of CD44 and Tumor-Targeted Cell Imaging

Simple, rapid, and sensitive detection of CD44 is of paramount importance since it plays pivotal roles in tumor initiation, growth and metastasis. Herein, we describe a novel method for sensitive, visual and facile fluorescence detection of CD44 and CD44-mediated cancer cell imaging, using a probe based on cationic conjugated polymer (CCP)-PFEP and fluoresceinamine-hyaluronan (FA-HA). HA is an anionic natural glycosaminoglycan that can specifically bind to the overexpressed CD44 on various kinds of cancer cells. PFEP and FA-HA formed a complex through electronic interactions, resulting in a highly efficient fluorescence resonance energy transfer (FRET) from PFEP to FA-HA; moreover, the efficiencies of FRET correlated with the concentrations of CD44 because the specific binding of HA-CD44 would separate FA-HA away from PFEP. This method did not require laborious and expensive dual-labeling or protein-labeling needed in previously reported detection methods of CD44. Just mix the sample and test solution containing the PFEP/FA-HA complex, and the results allowed naked-eye detection by observing fluorescent color of solutions with the assistance of a UV lamp. Most importantly, the use of a conjugated polymer with excellent amplification property as well as the specific binding of HA-CD44 endowed this method with high sensitivity and specificity, making it applicable for reliable quantitative detection of CD44. Furthermore, the PFEP/FA-HA complex formed nanoparticles in aqueous solution, and the nanoparticles can be selectively taken up by MCF-7 cells (cancer cell) through the HA-CD44 interaction, thereby giving rise to a dual-color tumor-targeted imaging probe with good photostability. The development of this fluorescent probe showed promising potential to make a reliable and routine method available for early diagnosis of cancer.

Fluorescent-magnetic poly(poly(ethyleneglycol)monomethacrylate)-grafted Fe3O4 nanoparticles from post-atom-transfer-radical-polymerization modification: synthesis, characterization, cellular uptake and imaging

Water-soluble poly(poly(ethyleneglycol)monomethacrylate)-grafted (P(PEGMA)-grafted) Fe3O4 nanoparticles synthesized via a solvent-free atom transfer radical polymerization (ATRP) method were conveniently surface-modified with 3-aminopropyltrimethoxysilane as anchor molecules to donate NH2 groups. Fluorescent magnetic nanoparticles (MNPs) were then obtained by covalently bonding fluorescein isothiocyanate (FITC) to the NH2 groups. The successful modification of the MNP surface was ascertained from FT-IR and XPS analyses, indicating that such a facile post-ATRP modification approach for introducing NH2 groups will extend the potential applications of polymer-coated MNPs produced via the ATRP method. The as-synthesized FITC-grafted MNPs (FITC-MNPs) showed good water solubility and stability, and have a uniform hydrodynamic particle size of 36.2 ± 2.2 nm. These nanoparticles are superparamagnetic with a saturation magnetization (Ms) of 23 emu g−1, which is sufficient for bioapplications. The uptake of the fluorescent MNPs by macrophage cells is about 2 pg Fe/cell, which is nearly similar to the pristine P(PEGMA)-grafted MNPs with good biocompatibility. Furthermore, an MMT assay using the 3T3 fibroblasts indicates the low cytotoxic effect of the FITC-MNPs. The FITC-MNPs can be efficiently uptaken by breast cancer cells up to 85 pg Fe/cell, which might be due to the high solubility of the P(PEGMA) chains in the cell membranes. Confocal microscope results showed that the FITC-MNPs were located inside the breast cancer cells but not within the cell membranes. These results indicate that FITC-MNPs with both fluorescence and magnetic functionalities have great potential for applications in bioimaging.

Oligo(p-phenyleneethynylene) embedded amphiphiles: synthesis, photophysical properties and self-assembled nanoparticles with high structural stability and photostability for cell imaging

Novel amphiphilic organic asymmetrically oligo(p-phenyleneethynylene) (OPE) conjugated molecules, ending with a hydrophobic alkyl chain and a hydrophilic methoxypolyethyleneglycol (MPEG) segment, were designed and synthesized. Due to the hydrophilic–hydrophobic nature of the asymmetrically amphiphilic OPE conjugated molecules, monodispersed fluorescent nanoparticles were obtained easily by self-assembly in aqueous solution. Through adjusting the length of MPEG chains in amphiphilic OPE, a series of nanoparticles with different water solubility were prepared. The aggregation behaviors of these dyes were investigated by dynamic light scattering (DLS) and transmission electron microscopy (TEM), which indicated that when the MPEG chains bonding with amphiphilic OPE are longer, smaller sized nanoparticles will be formed at the same concentration of 10−5 mol L−1. Besides, taking OPE–PEG1900 as an example, diversified aggregation behaviors under different concentrations can be inferred through DLS and TEM, which were also supported by ultraviolet absorption (UV) and photoluminescence (PL) analyses. Compared with previously reported conjugated-polymer nanoparticles consisting of amphiphiles without photoelectric features and oil-soluble conjugated-polymers through non-covalent encapsulation, the introduction of OPE chromophores into amphiphiles by covalent linkage efficiently enhanced the structural stability of nanoparticles. A photobleaching test under UV excitation revealed the high photostability of these OPE nanoparticles. In view of the good water solubility, biocompatibility, structural stability, photostability, and excellent photoelectric features of these nanoparticles, cellular imaging of human pancreatic cancer cells (PANC-1 cells) was conducted. Confocal microscopy results showed that the nanoparticles (OPE–PEG1000 and OPE–PEG1900) were located specifically within the cell cytoplasm. We believe that the OPE nanoparticles would play an important role as fluorescent biomarkers for long-term bioimaging, and offer new opportunities for good applicability in cell imaging and sensing in biomedical science.

A water-soluble conjugated polymer with azobenzol side chains based on “turn-on” effect for hypoxic cell imaging

A water-soluble conjugated polymer (WSCP) with enzymatic cleavable linkages (azobenzene) side chains for hypoxia imaging is reported. The fluorescence of the polymer would be recovered as the azobenzene moieties cleaved in hypoxia. This conjugated polymer was proved to be a good hypoxic sensor.

Self-assembled nanoparticles based on a cationic conjugated polymer/hyaluronan–cisplatin complex as a multifunctional platform for simultaneous tumor-targeting cell imaging and drug delivery

Multifunctional therapeutic systems that can realize simultaneous tumor-targeting imaging and drug delivery are highly desired to improve the therapeutic efficacy of conventional chemotherapy. Herein, we described a novel nanoparticle system prepared by electrostatic and hydrophobic self-assembly of a cationic conjugated polymer, PFEP, and anionic hyaluronan (HA) conjugated with the model anticancer drug cisplatin (CDDP). PFEP exhibited high fluorescence quantum yield, good photostability and low cytotoxity to meet the essential requests for cell imaging. HA is a natural glycosaminoglycan that possesses high specific affinity for the CD44 receptor overexpressed on surfaces of various cancer cells. The 20.2% CDDP-loaded PFEP/HA–CDDP complex nanoparticles (PHCNPs) were observed to comprise a compact hydrophobic inner core and a hydrophilic HA shell, and exhibit smaller size and better dispersity in aqueous solution than HA–CDDP nanoparticles (HCNPs) with the same drug loading content. Moreover, the fluorescence of PHCNPs was almost quenched due to the increased torsional conformation and aggregation of PFEP in the compact inner core. After PHCNPs were taken up by the target cancer cells through the specific HA–CD44 binding, HA was hydrolyzed by overexpressed hyaluronidase (HAase) in the cancer cells, which destroyed the nanoparticles, resulting in fluorescence recovery from PFEP and the release of CDDP. In vitro drug release studies also confirmed the HAase-promoted sustained CDDP release of PHCNPs. Therefore, tumor-targeting drug release and distribution in cells can be monitored by the recovered fluorescence signals. Furthermore, in vitro cytotoxicity studies demonstrated that the PHCNPs showed evident selective cytotoxicity, thereby leading to reduced side effects in normal cells. Therefore, the studies of conjugated polymers in multifunctional therapeutic system may offer a promising approach for improving the therapeutic efficacy of chemotherapy.

A macrocyclic oligoelectrolyte as a facial platform for absorbing hyaluronic acid oligomers for targeted cancer cellular imaging

A novel water-soluble macrocyclic oligoelectrolyte (MOE) was designed and synthesized by a simple Friedel–Crafts reaction as a facial platform for fabricating biological nanoparticles. The produced MOE with a unique three-dimension (3D) rigid structure consisted of a triphenylamine-based cyclic core and three oligofluorene arms, which protruded from the ring plane on both sides. The specific structure rendered MOE with good photoluminescence (PL) stabilities, low aggregation tendencies and excellent water-soluble properties in the form of well-defined smart organic dots (sub-10 nm) in aqueous solution. Using these organic dots as a template and OHAs, a biocompatible and linear oligosaccharide made straightforward contact with CD44 (a principal cell surface receptor for HA). As a stabilizer and biomarker, functional nanoparticles (MHNs-0.4) were fabricated via electronic interaction induced self-assembly in aqueous solution. The final confirmed MHNs-0.4 with suitable size (around 80 nm), good stability and fluorescent properties were found to be outstanding materials for the specific labelling of CD44-overexpressed human lung cancer cells (A549). The highlight of the study is that we provided a powerful and reliable platform, MOE-dots, for adsorbing various negatively charged molecules and broadening potential biological applications.