Micelles Formed by Polypeptide Containing Polymers Synthesized Via N-Carboxy Anhydrides and Their Application for Cancer Treatment

Knockdown of BACE1 by a multistage brain-targeting polyion complex improved memory and learning behaviors in APP/PS1 transgenic mouse model

Cleavage of Amyloid precursor protein (APP) by the β-site amyloid precursor protein cleaving enzyme 1 (BACE1) is the rate-limiting step in the production of amyloid-β (Aβ) synaptotoxins. The siRNA-mediated silencing to attenuate the expression of BACE1 to ameliorate cognitive dysfunction in mice had been investigated. To improve therapeutic gene delivery to the central nervous system, cationic copolymer poly(ethylene glycol)-b-poly[N-(N'-{N''-[N'''-(2-aminoethyl)-2-aminoethyl]-2-aminoethyl}-2-aminoethyl)aspartamide]-cholesterol was synthesized, then RVG29 and Tet1 peptides were exploited as ligands to construct a dual-targeting brain gene delivery polyion complex (Tet1/RVG29-PIC). The cell uptake of a coculture cell model showed that the Tet1/RVG29-PIC exhibited notable transport characteristics and possessed affinity towards nerve cells. In vivo transfection, Tet1/RVG29-PIC possessed the highest expression of luciferase in brain compared with that of RVG29-PIC or Tet1-PIC, which were 1.25 and 1.22 times respectively. Silence BACE1 expression using siRNA-expressing plasmid loaded Tet1/RVG29-PIC that improved behavioral deficits in the APP/PS1 mouse model, demonstrating the favorable brain delivery properties of Tet1/RVG29-PIC by synergistical engagement of GT1B and nicotinic acetylcholine receptors. Our results suggested that the nanoformulation has the potential to be exploited as a multistage-targeting gene vector for the CNS disease therapy.

Polypeptide-Based Systems: From Synthesis to Application in Drug Delivery

Synthetic polypeptides are biocompatible and biodegradable macromolecules whose composition and architecture can vary over a wide range. Their unique ability to form secondary structures, as well as different pathways of modification and biofunctionalization due to the diversity of amino acids, provide variation in the physicochemical and biological properties of polypeptide-containing materials. In this review article, we summarize the advances in the synthesis of polypeptides and their copolymers and the application of these systems for drug delivery in the form of (nano)particles or hydrogels. The issues, such as the diversity of polypeptide-containing (nano)particle types, the methods for their preparation and drug loading, as well as the influence of physicochemical characteristics on stability, degradability, cellular uptake, cytotoxicity, hemolysis, and immunogenicity of polypeptide-containing nanoparticles and their drug formulations, are comprehensively discussed. Finally, recent advances in the development of certain drug nanoformulations for peptides, proteins, gene delivery, cancer therapy, and antimicrobial and anti-inflammatory systems are summarized.

Improving aqueous solubility of paclitaxel with polysarcosine-b-poly(γ-benzyl glutamate) nanoparticles

New stealth amphiphilic copolymers based on polysarcosine (PSar) rather than poly(ethylene glycol) (PEG) have gained more attention for their use as excipients in nanomedicine. In this study, several polysarcosine-b-poly(γ-benzyl glutamate) (PSar-b-PGluOBn) block copolymers were synthesized by ring opening polymerization (ROP) of the respective N-carboxyanhydrides (NCAs) and were characterized by Fourier-transform infrared spectroscopy (FTIR), proton nuclear magnetic resonance (¹H NMR) and size-exclusion chromatography (SEC). Copolymers had different PGluOBn block configuration (racemic L/D, pure L or pure D), degrees of polymerization of PSar between 28 and 76 and PGluOBn between 9 and 93, molar masses (M_n) between 5.0 and 24.6 kg.mol^-1 and dispersities (Đ) lower than 1.4. Nanoparticles of PSar-b-PGluOBn loaded with paclitaxel (PTX), a hydrophobic anti-cancer drug, were obtained by nanoprecipitation. Their hydrodynamic diameter (D_h) ranged from 27 to 118 nm with polydispersity indexes (PDI) between 0.01 and 0.20, as determined by dynamic light scattering (DLS). Their morphology was more spherical for copolymers with a racemic L/D PGluOBn block configuration synthesized at 5 °C. PTX loading efficiency was between 63 and 92 % and loading contents between 7 and 15 %. Using PSar-b-PGluOBn copolymers as excipients, PTX apparent water-solubility was significantly improved by a factor up to 6600 to 660 µg.mL^-1.

Role of nucleic acid-based polymeric micelles in treating lung diseases

The prevalence of lung diseases is increasing year by year and existing drug therapies only provide symptomatic relief rather than targeting the actual cause. Nucleic acids can be used as an alternative therapeutic approach owing to their potential to reform a homeostatic balance by upregulating protective genes or downregulating damaging genes. However, their inherent properties, such as poor stability, ineffective cellular uptake, negative charge and so on, hinder their clinical utility. Such limitations can be overcome by exploiting the functional chemistry of polymeric micelles (PMs) for site-specific delivery, transfection efficiency and improved stability. With this objective, the present work describes the advancements made in designing nucleic acid-based PMs for treating lung diseases followed by approaches requiring consideration for clinical applications.

Development of Light-Responsive Poly(γ-Benzyl-L-Glutamate) as Photo Switches by a One-Step NCA Method

Synthesized polypeptide is attracting an increased interests due to its excellent biological characteristic and adjustable chemical properties in bio-related fields. But polypeptide itself has no switching properties, which is harmful to the development of its application as a control component. Herein, light-responsive poly(γ-benzyl-L-glutamate)s (PBLGs) is synthesized by a one-step NCA method using p-aminoazobenzene (m-AZO) and p-diaminoazobenzene (m-DAZO) as initiators. PBLGs exhibit amorphous characteristics with obvious T_g transition, which are 14°C for PBLG1 and 21°C for PBLG2. In order to forecast the structure-property information of PBLGs, theoretical UV-vis spectra as well as the energy gap between HOMO and LUMO is calculated by DFT calculation. Experimental results of UV-vis spectra exhibit similar characteristics to those of theorical UV-vis spectra except for the 40–50 nm red-shifting of absorbance peak. Furthermore, the absorbance intensities of PBLGs have a good linear relationship with their concentration, but their linearity range depending on concentration is completely different. Then, trans–cis transition under a different excitation source and cis–trans recovery in a dark environment are tracked in real-time by UV-vis spectra to evaluate the light response performances. It is found that UV light is the only effective excitation source for PBLG1, and blue light is another effective excitation source for PBLG2 besides UV light. Furthermore, the addition of alcohol and water as cosolvents has little effect on trans→cis transition in UV-light-excited systems, but it shortens recovery time of the cis→trans process in a dark environment. By contrast, the detectable isomerization process becomes unclear with the addition of alcohol in blue-light-excited system. Furthermore, either alcohol or water in solvents accelerate both the trans→cis and cis→trans process in a blue-light-excited system.

Enzymatic multifunctional biodegradable polymers for pH- and ROS-responsive anticancer drug delivery

A new family of multifunctional biodegradable block copolymers, PEG-poly(ω-pentadecalactone-co-N-methyldiethyleneamine sebacate-co-2,2'-thiodiethylene sebacate) (PEG-PMT), were synthesized via lipase-catalyzed copolymerization procedures. Amphiphilic PEG-PMT copolymers can be readily transformed into stable micellar nanoparticles through self-assembling processes in aqueous medium. The particle sizes increase dramatically after exposure of the particles to the acidic pH and high reactive oxygen species (ROS) conditions in tumor microenvironments, due to protonation of thioether groups and oxidation of amino groups in the PMT micelle cores, respectively. For example, docetaxel (DTX)-loaded PEG-PM-19 % TS micelles were triggered synergistically by acidic pH and ROS stimuli to release over 85 % of the anti-cancer drug. In particular, DTX/PEG-PMT-19 % TS and DTX/PEG-PMT-48 % TS micelles performed better than commercial Duopafei formulation in prohibiting growth of CT-26 tumors xenografed in vivo (70 % of tumor-inhibiting efficiency). Biosafety analysis revealed that DTX-loaded PEG-PMT nanoparticles possessed minimal toxicity towards normal organs, such as liver and kidney. These experimental data demonstrated that the pH- and ROS-responsive PEG-PMT micelles are promising vectors for both delivery of anti-tumor drugs and their controlled release at tumor intracellular sites.