Biocompatible poly(ethylene glycol)-poly(γ-cholesterol-L-glutamate) copolymers: Synthesis, characterization, andin vitrostudies

The pH-Dependent Controlled Release of Encapsulated Vitamin B1 from Liposomal Nanocarrier

In this work, we firstly presented a simple encapsulation method to prepare thiamine hydrochloride (vitamin B1)-loaded asolectin-based liposomes with average hydrodynamic diameter of ca. 225 and 245 nm under physiological and acidic conditions, respectively. In addition to the optimization of the sonication and magnetic stirring times used for size regulation, the effect of the concentrations of both asolectin carrier and initial vitamin B1 on the entrapment efficiency (EE %) was also investigated. Thermoanalytical measurements clearly demonstrated that after the successful encapsulation, only weak interactions were discovered between the carriers and the drug molecules. Moreover, the dissolution profiles under physiological (pH = 7.40) and gastric conditions (pH = 1.50) were also registered and the release profiles of our liposomal B1 system were compared with the dissolution profile of the pure drug solution and a manufactured tablet containing thiamin hydrochloride as active ingredient. The release curves were evaluated by nonlinear fitting of six different kinetic models. The best goodness of fit, where the correlation coefficients in the case of all three systems were larger than 0.98, was reached by application of the well-known second-order kinetic model. Based on the evaluation, it was estimated that our liposomal nanocarrier system shows 4.5-fold and 1.5-fold larger drug retention compared to the unpackaged vitamin B1 under physiological conditions and in artificial gastric juice, respectively.

DUP1 peptide modified micelle efficiently targeted delivery paclitaxel and enhance mitochondrial apoptosis on PSMA-negative prostate cancer cells

Prostate tumor cell targeted peptide fragment conjugated to the nano drug delivery system is a promising strategy for prostate cancer therapy. In this work, an amphiphilic copolymer Chol–PEG–DUP1 (PEG–cholesterol conjugated with DUP1 peptide) has been synthesized and characterized by proton nuclear magnetic resonance spectrum (¹H NMR). The paclitaxel (PTX) was encapsulated into the Chol–PEG–DUP1 micelles to obtain aqueous formulation with small particle size (within 200 nm) and high drug encapsulating efficiency. The DUP1 modified PTX micelle significantly enhanced the cytotoxicity of paclitaxel to PSMA negative prostate tumor cells (PC-3 cell) as demonstrated by MTT (IC₅₀ = 15.8 μg/mL compared to 68.7 μg/mL of free PTX). Flow cytometry analysis and fluorescence images revealed the DUP1 peptide fragments on the surface of micelles increased drug uptake (2.08-fold) by PC-3 cells. Flow cytometry and immunoblotting analysis showed the DUP1 modified PTX micelle enhanced the mitochondrial apoptosis-inducing capacity of PTX to PC-3 cells. In conclusion, Chol–PEG–DUP1 modified micelle was a reasonable, facile, and economic drug delivery system to target the PSMA-negative prostate cancer.

Synthesis of fatty phosphonic acid based polymethacrylamide by RAFT polymerization and self-assembly in solution

RAFT polymerization of dimethyl(methacrylamido)dodecylphosphonate (DMADP-(OMe)₂) was successfully achieved and resulting polymer proved to self-assemble in liquid media.

Novel hybrid virtual screening protocol based on molecular docking and structure-based pharmacophore for discovery of methionyl-tRNA synthetase inhibitors as antibacterial agents

Methione tRNA synthetase (MetRS) is an essential enzyme involved in protein biosynthesis in all living organisms and is a potential antibacterial target. In the current study, the structure-based pharmacophore (SBP)-guided method has been suggested to generate a comprehensive pharmacophore of MetRS based on fourteen crystal structures of MetRS-inhibitor complexes. In this investigation, a hybrid protocol of a virtual screening method, comprised of pharmacophore model-based virtual screening (PBVS), rigid and flexible docking-based virtual screenings (DBVS), is used for retrieving new MetRS inhibitors from commercially available chemical databases. This hybrid virtual screening approach was then applied to screen the Specs (202,408 compounds) database, a structurally diverse chemical database. Fifteen hit compounds were selected from the final hits and shifted to experimental studies. These results may provide important information for further research of novel MetRS inhibitors as antibacterial agents.

Development of a novel biocompatible poly(ethylene glycol)-block-poly(γ-cholesterol-L-glutamate) as hydrophobic drug carrier

A novel biomaterial poly(ethylene glycol)-block-poly(γ-cholesterol-l-glutamate) (mPEG-PCHLG) was designed and synthesized by introducing cholesterol side chains into this pegylated poly(amino acid) copolymers to enlarge the core space to increase the drug capacity. Paclitaxel (PTX) loaded mPEG-PCHLG nanoparticles (PTX-mPEG-PCHLG-Nps) were developed for the first time. The preparation method of nanoparticles was screened and optimized systemically. The optimal PTX-mPEG-PCHLG-Nps with the average diameter of 213.71 nm were constructed through the O/W single-emulsion solvent evaporation method. The entrapment efficiency and drug loading was 38.02 ± 4.51% and 93.90 ± 4.56%, respectively. PTX-mPEG-PCHLG-Nps were spherical and well-dispersed and displayed a dramatic sustained-release property. The in vitro cytotoxicity experiments demonstrated that the blank mPEG-PCHLG nanoparticles had no cytotoxicities on four tumor cell lines including A549, HepG-2, MCF-7 and C26, which implied that mPEG-PCHLG might be biocompatible. PTX-mPEG-PCHLG-Nps obtained the same cell growth inhibition activities as free PTX when incubated with the above tumor cells for 48h. It can be inferred that PTX-mPEG-PCHLG-Nps could probably have higher anticancer efficacy due to the inadequate release of PTX from nanoparticles. PTX-mPEG-PCHLG-Nps achieved the highest antitumor activity in A549 rather than HepG-2, MCF-7 and C26, thus PTX-mPEG-PCHLG-Nps could have a potential application in lung cancer therapy. All the data indicated that mPEG-PCHLG was one of biocompatible biomaterials and worth being widely investigated as hydrophobic antitumor drug carrier.

Self-assembled methoxy poly(ethylene glycol)-cholesterol micelles for hydrophobic drug delivery

To promote the application of methoxy poly(ethylene glycol)-cholesterol (mPEG-Chol), mPEG-Chol was used to prepare core-shell micelles encapsulating poorly water-soluble docetaxel (DTX-PM) by modified cosolvent evaporation method. Approaches to enhance DTX entrapment efficiency (EE) and minimize particle size were investigated in detail, including organic and aqueous phase composition, organic/aqueous phase ratio, and polymer concentration. In optimal formulation, micelles had higher EE (97.6%) and drug loading (4.76%) with the diameter of 13.76 ± 0.68 nm and polydispersity index of 0.213 ± 0.006. Transmission electron microscopy (TEM) showed that the micelles were spherical, and differential scanning calorimetry (DSC) analysis proved that DTX was successfully entrapped into mPEG-Chol micelles. The in vitro cytotoxicity experiments displayed that blank micelles had no effect on the growth of SKOV-3, BXPC-3, A549, and HepG-2 cells, demonstrating that mPEG-Chol was one of the biocompatible biomaterials. The half inhibition concentration of DTX-PM on SKOV-3, BXPC-3, A549, and HepG-2 cells were 10.08, 7.6, 28.37, and 125.75 ng/mL, respectively. DTX-PM had the similar antitumor activity to free DTX, indicating that mPEG-Chol was a promising micellar vector for hydrophobic drug delivery. In addition, this work provided a new and facile approach to prepare drug-loaded micelles with controllable performances.