ABSTRACT
Self-assembled prodrugs forming nanoaggregates are a promising approach to enhance the antitumor efficacy and to reduce the toxicity of anticancer drugs. To achieve this goal, doxorubicin was chemically conjugated to d-α-tocopherol succinate through an amide bond to form N-doxorubicin-α-d-tocopherol succinate (N-DOX-TOS). The prodrug self-assembled in water into 250 nm nanostructures when stabilized with d-α-tocopherol poly(ethylene glycol) 2000 succinate. Cryo-TEM analysis revealed the formation of nanoparticles with a highly ordered lamellar inner structure. NMR spectra of the N-DOX-TOS nanoparticles indicated that N-DOX-TOS is located in the core of the nanoparticles while PEG chains and part of the tocopherol are in the corona. High drug loading (34% w/w) and low in vitro drug release were achieved. In vitro biological assessment showed significant anticancer activity and temperature-dependent cellular uptake of N-DOX-TOS nanoparticles. In vivo, these nanoparticles showed a greater antitumor efficacy than free DOX. N-DOX-TOS nanoparticles might have the potential to improve DOX-based chemotherapy.
Subject(s)
Antineoplastic Agents/pharmacology , Doxorubicin/pharmacology , Drug Delivery Systems , Neoplasms, Experimental/drug therapy , Prodrugs/pharmacology , alpha-Tocopherol/pharmacology , Animals , Antineoplastic Agents/chemical synthesis , Antineoplastic Agents/chemistry , Cell Line, Tumor , Cell Proliferation/drug effects , Dose-Response Relationship, Drug , Doxorubicin/chemistry , Drug Screening Assays, Antitumor , Humans , MCF-7 Cells , Mice , Mice, Inbred BALB C , Molecular Structure , Nanostructures/chemistry , Neoplasms, Experimental/pathology , Prodrugs/chemical synthesis , Prodrugs/chemistry , Structure-Activity Relationship , alpha-Tocopherol/chemistryABSTRACT
This review deals with nanoporous materials made from the self-assembly of block copolymers with a special interest in the chemical functions covering the surface of their nanopores. A detailed overview of the existing methods and strategies to generate well-defined organic functional groups covering the surface of the pore walls is provided. This further enables to finely tune the affinity of the pore walls and to perform well-defined chemical reactions onto them, which is essential for further dedicated applications.
Subject(s)
Polymers/chemistry , Nanopores/ultrastructure , Polymers/chemical synthesis , Porosity , Surface PropertiesABSTRACT
The aim of this study was to develop tocol derivatives of chitosan able (i) to self-assemble in the gastrointestinal tract and (ii) to enhance the solubility of poorly soluble drugs. Among the derivatives synthesized, tocopherol succinate glycol chitosan (GC-TOS) conjugates spontaneously formed micelles in aqueous solution with a critical micelle concentration of 2 µg mL(-1). AFM and TEM analysis showed that spherical micelles were formed. The GC-TOS increased water solubility of 2 model class II drugs. GC-TOS loading efficiency was 2.4% (w/w) for ketoconazole and 0.14% (w/w) for itraconazole, respectively. GC-TOS was non-cytotoxic at concentrations up to 10 mg mL(-1). A 3.4-fold increase of the apparent permeation coefficient of ketoconazole across a Caco-2 cell monolayer was demonstrated. Tocol polymer conjugates may be promising vehicles for the oral delivery of poorly soluble drugs.
Subject(s)
Chitosan/chemistry , Drug Carriers , Itraconazole/chemistry , Ketoconazole/chemistry , Tocopherols/chemistry , Administration, Oral , Caco-2 Cells , Cell Survival/drug effects , Chemistry, Pharmaceutical , Chitosan/toxicity , Dose-Response Relationship, Drug , Drug Compounding , Humans , Intestinal Mucosa/drug effects , Intestinal Mucosa/metabolism , Itraconazole/administration & dosage , Itraconazole/metabolism , Ketoconazole/administration & dosage , Ketoconazole/metabolism , Kinetics , Micelles , Microscopy, Atomic Force , Microscopy, Electron, Transmission , Particle Size , Permeability , Solubility , Surface Properties , Technology, Pharmaceutical/methods , Tocopherols/toxicityABSTRACT
A polystyrene-block-poly(ethylene oxide) block copolymer bearing a photocleavable junction between the blocks is used to form nanoporous thin films with carboxylic acid functions homogeneously distributed on the pore walls. The presence of the carboxylic acid groups is evidenced by fluorescence spectroscopy after their reaction with a diazomethane functionalized fluorescent dye. In addition, the initial light-responsive thin film, acting as a photoresist, can be easily patterned to selectively generate porosity in predetermined areas. In that way, fluorescent patterns can be obtained as evidenced by fluorescent microscopy.
Subject(s)
Nanopores/ultrastructure , Photolysis , Polyethylene Glycols/chemistry , Polystyrenes/chemistry , Fluorescent Dyes/chemistry , Microscopy, Atomic Force , Microscopy, Fluorescence , Porosity , Surface PropertiesABSTRACT
Stimuli-responsive polymers are the subject of intense research because they are able to show responses to various environmental changes. Among those stimuli, light has attracted much attention since it can be localized in time and space and it can also be triggered from outside of the system. In this paper, we review light-responsive block copolymers (LRBCs) that combine characteristic features of block copolymers, e.g., self-assembly behavior, and light-responsive systems. The different photo-responsive moieties that have been incorporated so far in block copolymers as well as the proposed applications are discussed.
ABSTRACT
The regioselective hydrosilylation of terminal and internal alkynes catalyzed by the novel (IPr)Pt(AE) ( 7) (IPr = bis(2,6-diisopropylphenyl)imidazo-2-ylidene, AE = allyl ether) complex is presented. The (IPr)Pt(AE) catalyst displays enhanced activity and regioselectivity for the hydrosilylation of terminal and internal alkynes with low catalyst loading (0.1 to 0.05 mol %) when compared to the parent (IPr)Pt(DVDS) complex ( 6) (DVDS = divinyltetramethyldisiloxane). The reaction leads to exquisite regioselectivity in favor of the cis-addition product on the less hindered terminus of terminal and internal alkynes. The solvent effects were examined for the difficult hydrosilylation of benzylpropargyl ether. In light of the observed product distribution and kinetic data, a mechanistic scheme is proposed involving two competing catalytic cycles. One cycle leads to high regioselectivities while the other, having lost the stereodirecting IPr carbene ligand, displays low regiocontrol and activities. The importance of this secondary catalytic cycle is either caused by the strong coordinating ability of the alkyne or by the low reactivity of the silane or both.
