Formation of Uni-Lamellar Vesicles in Mixtures of DPPC with PEO-b-PCL Amphiphilic Diblock Copolymers

Nano delivery system for paclitaxel: Recent advances in cancer theranostics

Paclitaxel is one of the most effective chemotherapeutic drugs which processes the obvious curative effect for a broad range of cancers including breast, ovarian, lung, and head & neck cancers. Though some novel paclitaxel-loaded formulations have been developed, the clinical application of the paclitaxel is still limited due to its toxicity and solubility issues. Over the past decades, we have seen rapid advances in applying nanocarriers in paclitaxel delivery systems. The nano-drug delivery systems offer unique advantages in enhancing the aqueous solubility, reducing side effects, increasing permeability, prolonging circulation half-life of paclitaxel. In this review, we summarize recent advances in developing novel paclitaxel-loaded nano delivery systems based on nanocarriers. These nanocarriers show great potentials in overcoming the disadvantages of pure paclitaxel and as a result improving the efficacy.

Recent Advances on PEO-PCL Block and Graft Copolymers as Nanocarriers for Drug Delivery Applications

Poly(ethylene oxide)-poly(ε-caprolactone) (PEO-PCL) is a family of block (or graft) copolymers with several biomedical applications. These types of copolymers are well-known for their good biocompatibility and biodegradability properties, being ideal for biomedical applications and for the formation of a variety of nanosystems intended for controlled drug release. The aim of this review is to present the applications and the properties of different nanocarriers derived from PEO-PCL block and graft copolymers. Micelles, polymeric nanoparticles, drug conjugates, nanocapsules, and hybrid polymer-lipid nanoparticles, such as hybrid liposomes, are the main categories of PEO-PCL based nanocarriers loaded with different active ingredients. The advantages and the limitations in preclinical studies are also discussed in depth. PEO-PCL based nanocarriers could be the next generation of delivery systems with fast clinical translation. Finally, current challenges and future perspectives of the PEO-PCL based nanocarriers are highlighted.

Design and simulation of the liposomal model by using a coarse-grained molecular dynamics approach towards drug delivery goals

The simulated liposome models provide events in molecular biological science and cellular biology. These models may help to understand the cell membrane mechanisms, biological cell interactions, and drug delivery systems. In addition, the liposomes model may resolve specific issues such as membrane transports, ion channels, drug penetration in the membrane, vesicle formation, membrane fusion, and membrane protein function mechanism. One of the approaches to investigate the lipid membranes and the mechanism of their formation is by molecular dynamics (MD) simulations. In this study, we used the coarse-grained MD simulation approach and designed a liposome model system. To simulate the liposome model, we used phospholipids that are present in the structure of natural cell membranes (1,2-Dioleoyl-sn-glycero-3-phosphocholine (DOPC) and 1,2-Dioleoyl-sn-glycero-3-phosphoethanolamine (DOPE)). Simulation conditions such as temperature, ions, water, lipid concentration were performed based on experimental conditions. Our results showed a liposome model (ellipse vesicle structure) during the 2100 ns was formed. Moreover, the analysis confirmed that the stretched and ellipse structure is the best structure that could be formed. The eukaryotic and even the bacterial cells have elliptical and flexible structures. Usually, an elliptical structure is more stable than other assembled structures. The results indicated the assembly of the lipids is directed through short-range interactions (electrostatic interactions and, van der Waals interactions). Total energy (Van der Waals and electrostatic interaction energy) confirmed the designed elliptical liposome structure has suitable stability at the end of the simulation process. Our findings confirmed that phospholipids DOPC and DOPE have a good tendency to form bilayer membranes (liposomal structure) based on their geometric shapes and chemical-physical properties. Finally, we expected the simulated liposomal structure as a simple model to be useful in understanding the function and structure of biological cell membranes. Furthermore, it is useful to design optimal, suitable, and biocompatible liposomes as potential drug carriers.

Biodegradable PCL-b-PLA Microspheres with Nanopores Prepared via RAFT Polymerization and UV Photodegradation of Poly(Methyl Vinyl Ketone) Blocks

Biodegradable triblock copolymers based on poly(ε-caprolactone) (PCL) and poly(lactic acid) (PLA) were synthesized via ring-opening polymerization of L-lactide followed by reversible addition–fragmentation chain-transfer (RAFT) polymerization of poly(methyl vinyl ketone) (PMVK) as a photodegradable block, and characterized by FT-IR and ¹H NMR spectroscopy for structural analyses, and by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) for their thermal properties. Porous, biodegradable PCL-b-PLA microspheres were fabricated via the oil/water (O/W) emulsion evaporation method, followed by photodegradation of PMVK blocks by UV irradiation. The macro-chain transfer agent (CTA) synthesized by reacting a carboxylic-acid-terminated CTA—S-1-dodecyl-S′-(a,a′-dimethyl-a′′-acetic acid)trithiocarbonate (DDMAT)—with a hydroxyl-terminated PCL-b-PLA block copolymer was used to synthesize well-defined triblock copolymers with methyl vinyl ketone via RAFT polymerization with controlled molecular weights and narrow polydispersity. Gel permeation chromatography traces indicated that the molecular weight of the triblock copolymer decreased with UV irradiation time because of the photodegradation of the PMVK blocks. The morphology of the microspheres before and after UV irradiation was investigated using SEM and videos of three-dimensional confocal laser microscopy, showing a change in their surface texture from smooth to rough, with high porosity owing to the photodegradation of the PMVK blocks to become porous templates.