Polymer Vesicles Containing Small Vesicles within Interior Aqueous Compartments and pH-Responsive Transmembrane Channels

Therapeutic nanoreactors for detoxification of xenobiotics: Concepts, challenges and biotechnological trends with special emphasis to organophosphate bioscavenging

The introduction of enzyme nanoreactors in medicine is relatively new. However, this technology has already been experimentally successful in cancer treatments, struggle against toxicity of reactive oxygen species in inflammatory processes, detoxification of drugs and xenobiotics, and correction of metabolic and genetic defects by using encapsulated enzymes, acting in single or cascade reactions. Biomolecules, e.g. enzymes, antibodies, reactive proteins capable of inactivating toxicants in the body are called bioscavengers. In this review, we focus on enzyme-containing nanoreactors for in vivo detoxification of organophosphorous compounds (OP) to be used for prophylaxis and post-exposure treatment of OP poisoning. A particular attention is devoted to bioscavenger-containing injectable nanoreactors operating in the bloodstream. The nanoreactor concept implements single or multiple enzymes and cofactors co-encapsulated in polymeric semi-permeable nanocontainers. Thus, the detoxification processes take place in a confined space containing highly concentrated bioscavengers. The article deals with historical and theoretical backgrounds about enzymatic detoxification of OPs in nanoreactors, nanoreactor polymeric enveloppes, realizations and advantages over other approaches using bioscavengers.

Hierarchical Proteinosomes for Programmed Release of Multiple Components

A facile route to hierarchically organized multicompartmentalized proteinosomes based on a recursive Pickering emulsion procedure using amphiphilic protein-polymer nanoconjugate building blocks is described. The number of incarcerated guest proteinosomes within a single host proteinosome is controlled, and enzymes and genetic polymers encapsulated within targeted subcompartments to produce chemically organized multi-tiered structures. Three types of spatiotemporal response-retarded concomitant release, synchronous release or hierarchical release of dextran and DNA-are demonstrated based on the sequential response of the host and guest membranes to attack by protease, or through variations in the positioning of disulfide-containing cross-links in either the host or guest proteinosomes integrated into the nested architectures. Overall, our studies provide a step towards the construction of hierarchically structured synthetic protocells with chemically and spatially integrated proto-organelles.

Reversible Morphological Evolution of Responsive Giant Vesicles to Nanospheres by the Self-Assembly of Crystalline-b-Coil Polyphosphazene Block Copolymers

The preparation of long-term-stable giant unilamellar vesicles (GUVs, diameter ≥ 1000 nm) and large vesicles (diameter ≥ 500 nm) by self-assembly in THF of the crystalline-b-coil polyphosphazene block copolymers [N=P(OCH2CF3)2 ]n-b-[N=PMePh]m (4 a: n=30, m=20; 4 b: n=90, m=20; 4 c: n=200, m=85), which combine crystalline [N=P(OCH2CF3)2] and amorphous [N=PMePh] blocks, both of which are flexible, is reported. SEM, TEM, and wide-angle X-ray scattering experiments demonstrated that the stability of these GUVs is induced by crystallization of the [N=P(OCH2CF3)2] blocks at the capsule wall of the GUVS, with the [N=PMePh] blocks at the corona. Higher degrees of crystallinity of the capsule wall are found in the bigger vesicles, which suggests that the crystallinity of the [N=P(OCH2CF3)2] block facilitates the formation of large vesicles. The GUVs are responsive to strong acids (HOTf) and, after selective protonation of the [N=PMePh] block, they undergo a morphological evolution to smaller spherical micelles in which the core and corona roles have been inverted. This morphological evolution is totally reversible by neutralization with a base (NEt3), which regenerates the original GUVs. The monitoring of this process by dynamic light scattering allowed a mechanism to to be proposed for this reversible morphological evolution in which the block copolymer 4 a and its protonated form 4 a(+) are intermediates. This opens a route to the design of reversibly responsive polymeric systems in organic solvents. This is the first reversibly responsive vesicle system to operate in organic media.

Towards self-assembled hybrid artificial cells: novel bottom-up approaches to functional synthetic membranes

There has been increasing interest in utilizing bottom-up approaches to develop synthetic cells. A popular methodology is the integration of functionalized synthetic membranes with biological systems, producing "hybrid" artificial cells. This Concept article covers recent advances and the current state-of-the-art of such hybrid systems. Specifically, we describe minimal supramolecular constructs that faithfully mimic the structure and/or function of living cells, often by controlling the assembly of highly ordered membrane architectures with defined functionality. These studies give us a deeper understanding of the nature of living systems, bring new insights into the origin of cellular life, and provide novel synthetic chassis for advancing synthetic biology.

Poly(lactide-co-glycolide)-laponite-F68 nanocomposite vesicles through a single-step double-emulsion method for the controlled release of doxorubicin

Poly(lactide-co-glycolide) (PLGA)-laponite-F68 nanocomposite (PNC) vesicles were prepared through a technically facile, single-step water/oil/water double-emulsion method using ethyl acetate/water mixture. Vesicles of diameter 100 nm to 1.2 μm and average membrane thickness 30 nm were produced. Encapsulation with chemotherapeutic drug doxorubicin revealed unilamellar nature of the vesicle wall. PNC exhibited exfoliated morphology, enhanced thermal stability over neat PLGA, and a glass transition temperature of 54.29 °C. The zeta potential of -14.1 ± 0.231 for the vesicles revealed that the negatively charged PLGA surface is covered with neutral F68 in the vesicle wall. F68-Assisted formation of water/oil/water double emulsion of PNC in ethyl acetate/water mixture is proposed for the formation of the vesicles. Release characteristics of doxorubicin in phosphate-buffered saline (pH 7.4), cytotoxicity of bare and drug-loaded PNC vesicles with L929 cells, and uptake of doxorubicin with C6 fibroblast glioma cell line were also investigated.

Subcompartmentalized polymer hydrogel capsules with selectively degradable carriers and subunits

Subcompartmentalized hydrogel capsules (SHCs) with selectively degradable carriers and subunits are designed for potential applications in drug delivery and microencapsulated biocatalysis. Thiolated poly(methacrylic acid) and poly(N-vinyl pyrrolidone) are used to assemble 3-microm-diameter carrier capsules and 300-nm-diameter subunits, independently stabilized by a diverse range of covalent linkages. This paper presents examples of SHCs with tens of subcompartments and their successful drug loading, as well as selective degradation of the SHC carrier and/or subunits in response to multiple chemical stimuli.

A microreactor with thousands of subcompartments: enzyme-loaded liposomes within polymer capsules

Fully loaded: Noncovalent anchoring of liposomes into polymer multilayered films with cholesterol-modified polymers allows the preparation of capsosomes-liposome-compartmentalized polymer capsules (see picture). A quantitative enzymatic reaction confirmed the presence of active cargo within the capsosomes and was used to determine the number of subcompartments within this novel biomedical carrier system.