Poly(2-(dimethylamino)ethyl methacrylate)-Grafted Amphiphilic Block Copolymer Micelles Co-Loaded with Quercetin and DNA.

The synergistic effect of drug and gene delivery is expected to significantly improve cancer therapy. However, it is still challenging to design suitable nanocarriers that are able to load simultaneously anticancer drugs and nucleic acids due to their different physico-chemical properties. In the present work, an amphiphilic block copolymer comprising a biocompatible poly(ethylene glycol) (PEG) block and a multi-alkyne-functional biodegradable polycarbonate (PC) block was modified with a number of poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA) side chains applying the highly efficient azide-alkyne "click" chemistry reaction. The resulting cationic amphiphilic copolymer with block and graft architecture (MPEG-b-(PC-g-PDMAEMA)) self-associated in aqueous media into nanosized micelles which were loaded with the antioxidant, anti-inflammatory, and anticancer drug quercetin. The drug-loaded nanoparticles were further used to form micelleplexes in aqueous media through electrostatic interactions with DNA. The obtained nanoaggregates-empty and drug-loaded micelles as well as the micelleplexes intended for simultaneous DNA and drug codelivery-were physico-chemically characterized. Additionally, initial in vitro evaluations were performed, indicating the potential application of the novel polymer nanocarriers as drug delivery systems.

Polycarbonate-Based Copolymer Micelles as Biodegradable Carriers of Anticancer Podophyllotoxin or Juniper Extracts.

Podophyllotoxin (PPT) is used in the industrial production of efficient anticancer, antiviral and other drugs. Sinopodophyllum hexandrum or Podophyllum peltatum are natural sources of PPT, but at present they are considered as endangered species. Their PPT content is variable, depending on the growing conditions. Searching for new sources of PPT, some representatives of the genus Juniperus were found to exhibit efficient PPT biosynthesis. However, PPT is highly toxic and poorly soluble in water compound, which limits its clinical applications. In this connection, amphiphilic polymer micelles are considered to be suitable PPT carriers, aimed at increase in water solubility and decrease in toxicity. The present research deals with the evaluation of MPEG-polycarbonate block copolymer micelles loaded with PPT or juniper extracts. The active component-loaded polymer nanocarriers were characterized by dynamic and electrophoretic light scattering, as well as by transmission electron microscopy. The active component loading efficiency and loading capacity were also determined. Highly efficient antiproliferative activity of the loaded micelles was determined in a panel of cancer cell lines. The obtained amphiphilic nanocarriers, loaded with PPT-containing bioactive components, have application in future in vivo preclinical trials of their pharmacokinetics and pharmacodynamics as potential therapeutical agents in the prospective nanomedicine.

Solvent-Free Synthesis of Multifunctional Block Copolymer and Formation of DNA and Drug Nanocarriers.

The synthesis of well-defined multifunctional polymers is of great importance for the development of complex materials for biomedical applications. In the current work, novel and multi-amino-functional diblock copolymer for potential gene and drug delivery applications was successfully synthesized. A highly efficient one-step and quantitative modification of an alkyne-functional polycarbonate-based precursor was performed, yielding double hydrophilic block copolymer with densely grafted primary amine side groups. The obtained positively charged block copolymer co-associated with DNA, forming stable and biocompatible nanosized polyplexes. Furthermore, polyion complex (PIC) micelles with tunable surface charge and decorated with cell targeting moieties were obtained as a result of direct mixing in aqueous media of the multi-amino-functional block copolymer and a previously synthesized oppositely charged block copolymer bearing disaccharide end-group. The obtained well-defined nanosized PIC-micelles were loaded with the hydrophobic drug curcumin. Both types of nanoaggregates (polyplexes and PIC-micelles) were physico-chemically characterized. Moreover, initial in vitro evaluations were performed to assess the nanocarriers' potential for biomedical applications.

Green Synthesis and the Evaluation of a Functional Amphiphilic Block Copolymer as a Micellar Curcumin Delivery System.

Polymer micelles represent one of the most attractive drug delivery systems due to their design flexibility based on a variety of macromolecular synthetic methods. The environmentally safe chemistry in which the use or generation of hazardous materials is minimized has an increasing impact on polymer-based drug delivery nanosystems. In this work, a solvent-free green synthetic procedure was applied for the preparation of an amphiphilic diblock copolymer consisting of biodegradable hydrophobic poly(acetylene-functional carbonate) and biocompatible hydrophilic polyethylene glycol (PEG) blocks. The cyclic functional carbonate monomer 5-methyl-5-propargyloxycarbonyl-1,3-dioxane-2-one (MPC) was polymerized in bulk using methoxy PEG-5K as a macroinitiator by applying the metal-free organocatalyzed controlled ring-opening polymerization at a relatively low temperature of 60 °C. The functional amphiphilic block copolymer self-associated in aqueous media into stable micelles with an average diameter of 44 nm. The copolymer micelles were physico-chemically characterized and loaded with the plant-derived anticancer drug curcumin. Preliminary in vitro evaluations indicate that the functional copolymer micelles are non-toxic and promising candidates for further investigation as nanocarriers for biomedical applications.

Triblock Copolymer Micelles with Tunable Surface Charge as Drug Nanocarriers: Synthesis and Physico-Chemical Characterization.

Polymeric micelles have gained increasing interest as efficient drug delivery systems for cancer treatment and diagnosis. The aim of the present study was to construct and to evaluate novel polymeric nanosized drug carriers with tunable surface charges. Initially, amphiphilic triblock copolymers with predetermined molar mass characteristics were synthesized by applying controlled polymerization techniques. The copolymers self-assembled in aqueous media into core-shell spherical micelles, comprising a biodegradable hydrophobic poly(D,L-lactide) core, positively charged middle layer of poly((2-dimethylamino)ethyl methacrylate), and an outer shell of neutral hydrophilic poly(oligo(ethylene glycol) methyl ether methacrylate), with various densities of the short polyether side chains. The block copolymer micelles with average diameters of about 70 nm and surface charges varying from strongly positive to neutral were characterized and loaded with the model, natural, hydrophobic drug curcumin. Characteristics such as drug loading efficiency, in-vitro drug release profiles, and stability under physiological conditions were evaluated and discussed in terms of nanocarriers' composition. As a result, the most promising candidates for potential application in nanomedicine were identified.

Functional Polyglycidol-Based Block Copolymers for DNA Complexation.

Gene therapy is an attractive therapeutic method for the treatment of genetic disorders for which the efficient delivery of nucleic acids into a target cell is critical. The present study is aimed at evaluating the potential of copolymers based on linear polyglycidol to act as carriers of nucleic acids. Functional copolymers with linear polyglycidol as a non-ionic hydrophilic block and a second block bearing amine hydrochloride pendant groups were prepared using previously synthesized poly(allyl glycidyl ether)-b-polyglycidol block copolymers as precursors. The amine functionalities were introduced via highly efficient radical addition of 2-aminoethanethiol hydrochloride to the alkene side groups. The modified copolymers formed loose aggregates with strongly positive surface charge in aqueous media, stabilized by the presence of dodecyl residues at the end of the copolymer structures and the hydrogen-bonding interactions in polyglycidol segments. The copolymer aggregates were able to condense DNA into stable and compact nanosized polyplex particles through electrostatic interactions. The copolymers and the corresponding polyplexes showed low to moderate cytotoxicity on a panel of human cancer cell lines. The cell internalization evaluation demonstrated the capability of the polyplexes to successfully deliver DNA into the cancer cells.

Cationic (Co)polymers Based on N-Substituted Polyacrylamides as Carriers of Bio-macromolecules: Polyplexes, Micelleplexes, and Spherical Nucleic Acidlike Structures.

Novel N-substituted polyacrylamides bearing a cycle with two tertiary amines, poly(4-methyl-piperazin-1-yl)-propenone (PMPP) and its block copolymers with polylactide (PMPP-b-PLA), are synthesized and characterized. The homopolymers are water-soluble, whereas the block copolymers self-assemble in aqueous solution into a small size (Rh around 30 nm), are narrowly distributed, and exhibit core-shell micelles with good colloidal stability. Both the homopolymers and copolymer micelles are positively charged (ζ-potentials in the 13.8-17.6 mV range), which are employed for formation of electrostatic complexes with oppositely charged DNA. Complexes (polyplexes, micelleplexes, and spherical nucleic acidlike structures) in a wide range of N/P (amino to phosphate groups) ratios are prepared with short (115 bp) and long (2000 bp) DNA. The behavior and physicochemical properties of the resulting nanocarriers of DNA are strongly dependent on the polymer/polymer micelles' characteristics and the DNA chain length. All systems exhibit low cytotoxicity and good cellular uptake ability and show promise for gene delivery and regulation.

Does Nationality Matter for the Gunshot Brain Injury? Ten-Year Retrospective Observational Cadaveric Comparative Study for Gunshot TBI between Greece and Bulgaria.

OBJECTIVE: Penetrating brain trauma (PBT) caused by gunshot is one of the most lethal traumatic brain injuries (TBIs) and its management and confrontation is of great importance. METHODS: The authors searched retrospectively the archives from 2 similar autonomous laboratories of forensic science and toxicology in the Balkan peninsula for a 10-year period of time and included only fatal penetrating brain injuries. RESULTS: The study is conducted in 61 cadavers with gunshot PBT. All of the cadavers were victims of suicide attempt. The most common anatomical localization on the skull were the facial bones, followed by skull base, temporal and parietal bone, conducting a trajectory of the gunshot. Additional findings were atherosclerosis of the blood vessels and chronic diseases such as chronic obstructive pulmonary disease, cancer and fatty liver. CONCLUSION: PBI has a high mortality rate. There are factors and findings from the collected data differing between the 2 aforementioned nations. Either way, better preventative measures, gun control and healthcare system are highly necessary.

Multifunctional Polymer Nanocarrier for Efficient Targeted Cellular and Subcellular Anticancer Drug Delivery.

A multifunctional triblock copolymer intended for targeted drug delivery applications has been designed and successfully synthesized. Following various controlled polymerization and modification steps, a saccharide end-functionalized polyoxyethylene block was attached through an aromatic imine bond, cleavable in slightly acidic conditions, to an amphiphilic diblock copolymer comprising a biodegradable hydrophobic block and a partially modified with mitochondria targeting ligands polycationic block. The micelles formed from the triblock copolymer in aqueous media possess key functions (cleavable "stealth" shield, targeting groups) needed for safe extracellular transport, successful cell internalization, and drug delivery to the target cellular organelles. The multifunctional nanocarriers were loaded with the plant-derived anticancer drug curcumin, and in vitro analyses revealed that their cytotoxic, apoptogenic, and NF-κB-inhibitory effects on target cells were superior over those of the free drug and non-functionalized polymer micelles of similar composition. Moreover, the enhanced cellular internalization and mitochondrial accumulation of the multifunctional nanocarriers compared to their non-functionalized analogues was visualized by fluorescence microscopy. The results indicate that the presented multifunctional micelles have a potential for application in nanomedicine for enhanced organelle-specific drug delivery.

Insulin/poly(ethylene glycol)-block-poly(L-lysine) Complexes: Physicochemical Properties and Protein Encapsulation.

Insulin (INS) was encapsulated into complexes with poly(ethylene glycol)-block-poly(L-lysine) (PEG-b-PLys), which is a polypeptide-based block copolymer (a neutral-cationic block polyelectrolyte). The particular cationic-neutral block copolymer can complex INS molecules in aqueous media via electrostatic interactions. Light-scattering techniques are used to study the complexation process and structure of the hybrid nanoparticles in a series of buffers, as a function of protein concentration. The physicochemical and structural characteristics of the complexes depend on the ionic strength of the aqueous medium, while the concentration of PEG-b-PLys was constant through the series of solutions. As INS concentration increased the size distribution of the complexes decreased, especially at the highest ionic strength. The size/structure of complexes diluted in biological medium indicated that the copolymer imparts stealth properties and colloidal and biological stability to the complexes, features that could in turn affect the clearance properties in vivo. Therefore, these studies could be a rational roadmap for designing the optimum complexes/effective nanocarriers for proteins and peptides.

Polymer gene delivery vectors encapsulated in thermally sensitive bioreducible shell.

Stable, nanosized polyelectrolyte complexes between rationally designed thermally sensitive block copolymers and plasmid DNA (polyplexes) were formed and their in vitro transfection efficiency was tested. The polyplexes were further stabilized through encapsulation into a biodegradable polymer shell. Although reduced as compared to that of the corresponding polyplexes, the encapsulated systems still show acceptable transfection efficiency. That opens the possibility to tune the balance between the safe transport and efficient delivery of DNA into the cells.

Nucleation of insulin crystals in a wide continuous supersaturation gradient.

Modifying the classical double pulse technique, by using a supersaturation gradient along an insulin solution contained in a glass capillary tube, we found conditions appropriate for the direct measurement of nucleation parameters. The nucleation time lag has been measured. Data for the number of crystal nuclei versus the nucleation time were obtained for this hormone. Insulin was chosen as a model protein because of the availability of solubility data in the literature. A comparison with the results for hen-egg-white lysozyme, HEWL was performed.

Synthesis of nearly monodisperse polystyrene-polypeptide block copolymers via polymerisation of N-carboxyanhydrides.

Primary amine hydrochlorides promote a well-controlled ring-opening polymerisation of Z-L-lysine-N-carboxyanhydride in DMF at 40-80 degrees C; the polystyrene-poly(Z-L-lysine) block copolymers synthesised exhibit a very narrow molecular weight distribution, close to a Poisson distribution.