A cationic gene delivery vector, guanidinylated disulfide-containing poly(amido amine) (CAR-CBA), was synthesized by Michael addition reaction between N,N′-cystaminebisacrylamide (CBA) and guanidine hydrochloride (CAR). Gel permeation chromatography (GPC) was used to evaluate the molecular weight of synthesized CAR-CBA. Polyethyleneimine (PEI) with molecular weight of 25 kDa was adopted as a reference, and polyethylene glycols (PEG) with different molecular weights were used to establish a standard curve for determining the molecular weight of CAR-CBA. The effects of two critical factors, namely columns and eluents, on the molecular weight measurement of CAR-CBA were investigated to optimize the GPC quantitative method. The results showed that Ultrahydrogel columns (120, 250) and HAc–NaAc (0.5 M, pH 4.5) buffer solution were the optimal column and GPC eluent, respectively. The molecular weight of the synthesized CAR-CBA was analyzed by the optimized GPC method and determined to be 24.66 kDa.Download high-res image (52KB)Download full-size image

Carbon dots (CDs) have shown great potential in imaging and drug/gene delivery applications. In this work, CDs functionalized with a nuclear localization signal peptide (NLS-CDs) were employed to transport doxorubicin (DOX) into cancer cells for enhanced antitumor activity. DOX was coupled to NLS-CDs (DOX-CDs) through an acid-labile hydrazone bond, which was cleavable in the weakly acidic intracellular compartments. The cytotoxicity of DOX-CD complexes was evaluated by the MTT assay and the cellular uptake was monitored using flow cytometry and confocal laser scanning microscopy. Cell imaging confirmed that DOX-CDs were mainly located in the nucleus. Furthermore, the complexes could efficiently induce apoptosis in human lung adenocarcinoma A549 cells. The in vivo therapeutic efficacy of DOX-CDs was investigated in an A549 xenograft nude mice model and the complexes exhibited an enhanced ability to inhibit tumor growth compared with free DOX. Thus, the DOX-CD conjugates may be exploited as promising drug delivery vehicles in cancer therapy.

•Lovastatin and lovastatin acid were determined in rat plasma by UPLC–MS/MS.•Positive/negative ion-switching function was used to monitor the two analytes.•The method was proved to be sensitive, selective and rapid.•It has been successfully applied to pharmacokinetic study of LOV-NS.Lovastatin (LOV) is an antihyperlipidemic agent which exhibits low bioavailability due to its poor solubility. Therefore, a nanosuspension (NS) was developed as an efficient strategy to improve its oral bioavailability. To evaluate the pharmacokinetics of LOV-NS, a novel, sensitive, and rapid UPLC–MS/MS method was developed and validated for the simultaneous determination of LOV and its metabolite lovastatin acid (LOVA) in rat plasma. Simvastatin (IS) was chosen as the internal standard, and a liquid-liquid extraction method was used to isolate LOV and LOVA from biological matrices. The analytes were analyzed on an Acquity UPLC BEH C18 column, and a gradient program was applied at a flow rate of 0.2 mL/min. Then, a tandem quadrupole mass spectrometer coupled with a positive/negative ion-switching electrospray ionization interface was employed to detect the analytes. Quantitation of the analytes was performed in the multiple reaction monitoring mode to monitor the transitions of m/z 427.1 → 325.0 for LOV and m/z 441.1 → 325.0 for IS in the positive ion mode and m/z 421.0 → 101.0 for LOVA in the negative ion mode, respectively. The method was validated over the concentration range 0.25–500 ng/mL (r2 ≥ 0.99) for both LOV and LOVA. The intra-day and inter-day precision (RSD%) of LOV and LOVA were less than 12.87% and the accuracy (RE%) was less than 5.22%. The average extraction recoveries were 90.1% and 91.9% for LOV and LOVA, and the matrix effects were found to be between 85% and 115%. The stability study showed that both analytes were stable during the experiment. Finally, this method has been successfully applied to a pharmacokinetic study in rats following a single oral dose of 10 mg/kg LOV-NS.

Strong blue fluorescent polyethylene glycol (PEG) anchored carbon nitride dots (CDs@PEG) with a high quantum yield (QY) of 75.8% have been synthesized by a one step hydrothermal treatment. CDs with a diameter of ca. 6 nm are well dispersed in water and present a graphite-like structure. Photoluminescence (PL) studies reveal that CDs display excitation-dependent behavior and are stable under various test conditions. Based on the as-prepared CDs, we designed novel cell nucleus targeting imaging carbon dots functionalized with a nuclear localization signal (NLS) peptide. The favourable biocompatibilities of CDs and NLS modified CDs (NLS-CDs) are confirmed by in vitro cytotoxicity assays. Importantly, intracellular localization experiments in MCF7 and A549 cells demonstrate that NLS-CDs could be internalized in the nucleus and show blue light, which indicates that CDs may serve as cell nucleus imaging probes.

•Rod and spherical shaped nanocrystals with similar particle sizes were prepared.•LOV-RNs and LOV-SNs have the same crystalline state.•LOV-RNs have larger surface areas than LOV-SNs.•LOV-RNs exhibit superior dissolution rate and oral bioavailability over LOV-SNs.•It is important to consider the shape factor when designing oral nanocrystals.The objective of this study was to compare the in vitro and in vivo performance of rod shaped and spherical like nanocrystals for oral administration. Lovastatin (LOV) was chosen as the model drug and LOV rod shaped nanocrystals (LOV-RNs) and spherical like nanocrystals (LOV-SNs) were prepared by sonoprecipitation and bead milling, respectively. The dry powders obtained following freeze-drying were characterized by hydrodynamic diameter, polydispersity index, zeta potential, transmission electron microscope, scanning electron microscope, atomic force microscope, differential scanning calorimetry, Fourier transform infrared spectroscopy, and in vitro dissolution test. The pharmacokinetic study was performed in beagle dogs. The results obtained showed that LOV-RNs and LOV-SNs had similar hydrodynamic diameters (500.6 ± 21.0 nm versus 503.2 ± 20.4 nm), and the same crystalline state. The dissolution test showed that LOV-RNs had a higher dissolution rate than LOV-SNs. The AUC(0–24 h) values of LOV-RNs and LOV-SNs were higher than Junning® for both LOV (p < 0.05 for LOV-RNs, and p > 0.05 for LOV-SNs) and lovastatin acid (p > 0.05). More importantly, the oral bioavailability of LOV-RNs was higher than LOV-SNs (p > 0.05). The findings of this study show that the crystal shape has a significant effect on oral bioavailability.Sonoprecipitation was used to prepare lovastatin (LOV) rod shaped nanocrystals (LOV-RNs), and wet media milling was applied for the preparation of spherical like nanocrystals (LOV-SNs). LOV-RNs exhibit superior in vitro dissolution and in vivo bioavailability over LOV-SNs.

•A new method, microwave-assisted solution polymerization, has been developed for the synthesis of poly (d,l-lactide)-graft-pullulan (PL).•This technique can condense the time of synthesis from hours to minutes.•This method increased the yield of PL and lactide conversion.•This method can produce PL with different characteristics.•PL was applied for anti-cancer drug curcumin delivery as the forms of micelles and microparticles.A novel microwave-assisted method was developed to synthetize amphiphilic copolymer poly (d,l-lactide)-graft-pullulan (PL) in a monomode microwave reactor. The effects of microwave power, ratio of catalyst/lactide, ratio of lactide/hydroxyl group of pullulan (lactide/OH-P) and solvent on the synthesis were further investigated. Three samples (designated as PL 8, 9, and 6), characterized by FT-IR and NMR, were applied to form nanoparticles and microparticles investigated by dynamic light scattering, fluorescence spectroscopy and transmission electron microscopy. PL9 and PL6 were used for loading model drug curcumin. The results indicated that microwave-assisted synthesis shortened the copolymerization of PL, with higher yield and lactide conversion, from 24 h to 5 min and showed some specific microwave effects compared with conventional oil heating. PL with a relative higher substitution degree gave nanoparticles with smaller sizes and critical aggregation concentrations. The solubility of curcumin was increased to 1.97 mg mL−1 as the forms of nanoparticles.

Stable water-based magnetic fluids were synthesized by a sequential process involving the co-precipitation of Fe3* and Fe2+ with NH3H2O to prepare magnetic particles, then two stabilizers, sodium oleate (SO) and Dextran T-40, were used to coat the particles. The prepared magnetic particles were stabilized against agglomeration by the bilayer structure formed by SO, as an inner layer, adsorbed firmly onto the surface of the magnetic particles by hydrogen bonding, and dextran T-40, as an outer layer, interacted with SO in the same way, which were confirmed by Fourier transform infrared (FT-IR). The particle morphology and size were characterized using transmission electron microscopy (TEM), indicating the formation of single-domain nanoparticles with a mean diameter of about 26.1 nm. The saturation magnetization (Ms) value of 42.1 emu/g was obtained by vibrating sample magnetometry (VSM). Also, X-ray powder diffraction (XRD) analysis showed that the powder phase was almost entirely magnetite. The bilayer-coated magnetic fluid can be used as a therapeutic agent to release thermal energy as determined in hyperthermic tests.

Hydrophobic ion-pairing (HIP) complexation has emerged as an efficient approach to enhance the entrapment of therapeutic peptides in the biodegradable polymer matrix. In the present study, we developed an innovative extraction method for preparation of HIP-colistin (CST, a polycationic peptide) using various water-insoluble anionic lipids. To determine the loading mechanism of HIP-CST entrapped poly(lactic acid) (PLA) nanoparticles (HIP-CST-PLA-NPs), the effects of anionic lipids and PLA molecular weight (Mw) on the unentrapped fraction (uf) of CST in PLA-NPs were investigated. And CST release mechanism from HIP-CST-PLA-NPs was also investigated by evaluating their release behavior and NP swelling. It is showed that HIP-CST retention in the PLA-NPs was imposed by their physical localization in the networks of the PLA chains, rather than the electrostatic attraction between anionic lipid and CST in serum. And HIP-CST-PLA-NPs in serum exhibited the swelling-controlled release behavior with a substantially accelerated release and NP swelling observed in comparison with that in phosphate buffer. Our results can effectively guide the preparation of biodegradable polymer based modified drug release systems with desired properties for peptides delivery.Download high-res image (239KB)Download full-size image