Linzhu Zhou

A supramolecular approach to the preparation of charge-tunable dendritic polycations for efficient gene delivery

A facile supramolecular approach for the preparation of charge-tunable dendritic polycations, by a combination of the multi-functionality of dendritic polymers with the dynamic-tunable ability of supramolecular polymers, has been developed. It provides a new strategy for designing and developing efficient gene vectors via noncovalent interactions.

Synergistic Combination Chemotherapy of Camptothecin and Floxuridine through Self-Assembly of Amphiphilic Drug-Drug Conjugate.

Combination chemotherapy has been widely applied in cancer treatment; however, the cocktail administration of combination chemotherapy could cause the nonuniform biodistribution of anticancer agents, thus impairing the therapeutic efficacy. In the present study, to address this concern, we proposed a novel strategy of preparing self-assembled nanoparticles from amphiphilic drug-drug conjugate for synergistic combination chemotherapy. The conjugate was synthesized by two-step esterification of hydrophobic camptothecin (CPT) and hydrophilic floxuridine (FUDR) through a linker compound. Because of its amphiphilic nature, the CPT-FUDR conjugate self-assembled into stable nanoparticles which could simultaneously release fixed dosage of the two drugs in cancer cells. In vitro studies demonstrated synergistic anticancer efficacy of the CPT-FUDR nanoparticles including improved cell apoptosis, varied cell cycle arrest, as well as effective inhibition of cancer cell proliferation.

Multi‐Responsive Polypeptidosome: Characterization, Morphology Transformation, and Triggered Drug Delivery

The biodegradable polymeric nanomedicines that may be integrated with multi-stimuli-sensitivity to achieve triggered or on-demand drug release kinetics are challenging for polymer therapeutics and drug delivery systems. By controlling the structure transformation of one polypeptide-b-PEO copolymer, a novel multi-responsive polypeptide-based vesicle (polypeptidosome) presents the combined sensitivity of multiple physiological and clinic-related stimuli, and both morphology and size of the polypeptidosome are changed during the triggered process. The designer polypeptide has unique structures composed of 1) light-responsive o-nitrobenzyl groups, 2) oxidizable thioether linkers, 3) photo-caged redox thiol groups on parent poly(L-cysteine), and 4) tunable conformation, which enable the polypeptidosome to have a peculiar multi-response. The anticancer drug doxorubicin can be released in a controlled or on-off manner. The combination stimuli of UV irradiation and H2 O2 oxidation induces a large effect and a lower IC50 of 3.80 μg doxorubicin (DOX) equiv/mL compared to 5.28 μg DOX equiv/mL of individual H2 O2 trigger.

In situ preparation of magnetic nonviral gene vectors and magnetofection in vitro

Magnetic nonviral gene vectors were in situ prepared in the presence of ferrous salts and hyperbranched poly(ethylenimine)s (HPEI) with different molecular weights. HPEI, one of the most promising nonviral vectors, was not only utilized as the nanoreactor and stabilizer to prepare magnetic nanoparticles, but also skillfully used as a base supplier to avoid introducing alkali hydroxide or ammonia. Magnetic nonviral gene vectors with various magnetite contents and saturation magnetizations were obtained by changing the weight ratio of HPEI to FeSO(4).7H(2)O and the molecular weight of HPEI. MTT assays suggested that the resulting magnetite/HPEI gene vectors had lower cytotoxicity compared with pure HPEI. The magnetite/HPEI nonviral gene vectors were used for magnetofection. It was found that the luciferase expression level mediated by magnetite/HPEI in COS-7 cells under a magnetic gradient field was approximately 13-fold greater than that of standard HPEI transfection.

Self-Assembled Nanoparticles of Amphiphilic Twin Drug from Floxuridine and Bendamustine for Cancer Therapy.

We report here an amphiphilic twin drug strategy directly using small molecular hydrophilic and hydrophobic anticancer drugs to self-assemble into nanoparticles with a high and fixed drug content, which can solve problems of anticancer drug delivery including poor water solubility, low therapeutic indices, and severe side effects. The twin drug has been prepared by the esterification of the hydrophilic anticancer drug floxuridine (FdU) with the hydrophobic anticancer drug bendamustine (BdM). Due to its inherent amphiphilicity, the FdU-BdM twin drug can self-assemble into stable and well-defined nanoparticles. After FdU-BdM twin drug enters into cells, the ester linkage between hydrophilic and hydrophobic drugs is readily cleaved by hydrolysis to release free FdU and BdM. Since both FdU and BdM can kill cancer cells, the FdU-BdM twin drug nanoparticles can overcome the multidrug resistance (MDR) of tumor cells and present an excellent anticancer activity. This strategy can be extended to other hydrophilic and hydrophobic anticancer drugs to synthesize amphiphilic twin drugs which can form nanoparticles to self-deliver drugs for cancer therapy.

A Sweet Polydopamine Nanoplatform for Synergistic Combination of Targeted Chemo-Photothermal Therapy

Inspired by sweet or sugar-coated bullets that are used for medications in clinics and the structure and function of biological melanin, a novel kind of sweet polydopamine nanoparticles and their anticancer drug doxorubicin loaded counterparts are prepared, which integrate an active targeting function, photothermal therapy, and chemotherapy into one polymeric nanocarrier. The oxidative polymerization of lactosylated dopamine and/or with dopamine are performed under mild conditions and the resulting sweet nanoparticles are thoroughly characterized. When exposed to an 808 nm continuous-wave diode laser, the magnitude of temperature elevation not only increases with the concentration of nanoparticles, but can also be tuned by the laser power density. The nanoparticles possess strong near infrared light absorption, high photothermal conversion efficiency, and good photostability. The nanoparticles present tunable binding with RCA120 lectin and a targeting effect to HepG2 cells, confirmed by dynamic light scattering, turbidity analysis, MTT assay, and flow cytometry. Importantly, the sweet nanoparticles give the lowest IC50 value of 11.67 μg mL(-1) for chemo-photothermal therapy compared with 43.19 μg mL(-1) for single chemotherapy and 67.38 μg mL(-1) for photothermal therapy alone, demonstrating a good synergistic effect for the combination therapy.

Hyperbranched glycoconjugated polymer from natural small molecule kanamycin as a safe and efficient gene vector

The exploration of safe and efficient polycationic gene vectors from natural small molecules such as kanamycin was proposed. Cationic hyperbranched glycoconjugated polymer was synthesized by the Michael-addition polymerization of kanamycin and N,N′-methylenebisacrylamide, and the resultant product was well characterized by FTIR, 1H NMR, 13C NMR, SEC-MALLS and ζ-potential analyses. The nitrogen content (7.3%) of this kanamycin-based hyperbranched glycoconjugated polymer was much lower than that (32.6%) of polyethylenimine (PEI) control. Moreover, this resultant polymer could be degraded in acidic conditions. Therefore, the hyperbranched glycoconjugated polymer showed low cytotoxicity, even lower than that of natural biomacromolecule chitosan. Due to the existence of various primary, secondary and tertiary amines in the polymer backbone, hyperbranched glycoconjugated polymer exhibited high buffering capacity and strong pDNA condensation ability. In vitro transfection showed that the luciferase expression of hyperbranched glycoconjugated polymer was about 4.4 × 108 RLU per mg protein, approximately 33-fold greater than that of chitosan transfection. These results demonstrate that the construction of highly branched polycations from natural small molecules provides a new opportunity for developing safe and efficient gene vectors.

NIR-responsive polypeptide copolymer upconversion composite nanoparticles for triggered drug release and enhanced cytotoxicity

Near infrared (NIR) light-responsive polymeric nanomedicines might achieve spatiotemporal, pulsatile, and on-demand drug release profiles and are appealing as a noninvasive technology for various clinical therapies. Polypeptide copolymer composite nanoparticles with different amounts of upconversion nanoparticles (UCNPs) were successfully fabricated in aqueous solution, and the NIR sensitivity of the composite nanoparticles was characterized by time-resolved UV-vis spectroscopy, on-line dynamic light scattering, and transmission electron microscopy. The composite nanoparticles disassembled with the help of UCNPs converting NIR light into UV light, and the NIR-responsive time can be tuned by both the loaded amount of UCNPs and the polypeptide chain length. The composite nanoparticles loaded with the anticancer drug doxorubicin (DOX) can release DOX in a controllable and/or pulsatile manner, and the drug release profile can be manipulated by NIR light. The DOX-loaded composite nanoparticles can be quickly internalized by HeLa cells and then release DOX inside the cells, as evidenced by flow cytometry and confocal laser scanning microscopy. After 5 or 10 min of NIR irradiation, the half maximal inhibitory concentration (IC50) for the DOX-loaded composite nanoparticles dropped to 5.08 μg DOX equiv. mL−1 or 2.95 μg DOX equiv. mL−1, respectively, compared to 8.26 μg DOX equiv. mL−1 for the non-irradiated sample, demonstrating a tunable NIR-triggered cytotoxicity. This work provides a versatile platform for the fabrication of NIR-responsive polypeptide copolymer nanomedicines with the potential for on-demand drug delivery and cancer therapy.

Comb-like poly(L-cysteine) derivatives with different side groups: synthesis via photochemistry and click chemistry, multi-responsive nanostructures, triggered drug release and cytotoxicity

A series of comb-like graft polypeptides having different side groups and tunable grafting ratios were prepared by sequential photocleavage reactions and Michael-type thiol–ene addition, as fully characterized by 1H NMR, gel permeation chromatography, FT-IR, and circular dichroism spectroscopy. The grafting ratio of the resulting polypeptides was close to the photolysis ratio of o-nitrobenzyl derived poly(L-cysteine) precursors. Both electrolytic acrylic acid (AA) and 2-(dimethylamino) ethyl acrylate (DMAEA) produced a larger disturbance on the ordered conformations than neutral poly(ethylene glycol) (PEG) methyl ether acrylate although the molecular weight and size of AA and DMAEA are much smaller than those of PEG. The polypeptide vesicles and micelles with a neutral or electrolytic corona could be facilely fabricated from these side group modified poly(L-cysteine)s, and the polypeptide vesicles exhibited both light- and redox-sensitivity in aqueous solution. As characterized by the MTT assay, flow cytometry, and CLSM, the anticancer drug doxorubicin (DOX) loaded nanoparticles quickly entered into HeLa cells and presented photo- and reduction-triggered cytotoxicity. The half maximal inhibitory concentration of HeLa cells (IC50) for the irradiated nanoparticles dropped to 0.40 μg DOX equiv. per mL compared to 1.27 μg DOX equiv. per mL for the non-irradiated sample; however, the IC50 for the irradiated sample increased about 1.5-fold after the BSO inhibitor treatment. Importantly, this work not only establishes a facile method for the preparation of comb-like graft polypeptides by the combination of photochemistry and thiol–ene click chemistry, but also provides a promising platform for on-demand nanomedicine and cancer therapy.

PEGylated poly(diselenide-phosphate) nanogel as efficient self-delivery nanomedicine for cancer therapy

A redox-responsive PEGylated poly(diselenide-phosphate) nanogel with biocompatibility and biodegradability has been designed and prepared. Firstly, monomethoxy poly(ethylene glycol) (mPEG) was used to initiate the ring opening polymerization (ROP) of the cyclic phosphate monomer 2-(2-(2-(4-methyl-benzene-sulfonate)-ethoxy)ethoxy)ethoxy-2-oxo-1,3,2-dioxaphospholane (MBS-EEEP) to produce a diblock copolymer with 4-methylbenzenesulfonate (MBS) side groups in the block of polyphosphate. Then, the nanogel with a polyphosphate core cross-linked by many hydrophobic diselenide bonds and a hydrophilic PEG shell was obtained by using sodium diselenide as a crosslinking agent to react with the MBS side groups in the diblock copolymers. Dynamic light scattering and transmission electron microscopy measurements reveal that the nanogel has a spherical morphology with an average diameter of 150 nm. The systematic evaluation in vitro demonstrates that the nanogel can be endocytosed easily by tumor cells, and potently inhibit the proliferation of the tested cancer cells, with only slight cytotoxicity to normal cells. After 48 h incubation, the 50% growth inhibitory concentration (IC50) of the nanogel against the three tested cancer cell lines ranges from 12 to 16 μg mL−1. The remarkable anticancer efficacy might be ascribed to the active selenium species released from the nanogel in the presence of over expressed reactive peroxides and GSH within cancer cells. Besides its inherent anticancer ability, this nanogel may encapsulate other hydrophobic anticancer drugs for a cocktail therapy.