Tailored drug-release from multi-functional polymer-peptide hybrid vesicles

Hybrid Polymer Vesicles: Controllable Preparation and Potential Applications

Hybrid polymer vesicles contain functional nanoparticles (NPs) in their walls, interfaces, coronae, or cavities. NPs render the hybrid vesicles with specific physical properties, while polymers endow them with structural stability and may significantly reduce the high toxicity of NPs. Therefore, hybrid vesicles integrate fascinating multifunctions from both NPs and polymeric vesicles, which have gained tremendous attention because of their diverse promising applications. Various types of delicate hybrid polymeric vesicles with size control and tunable localization of NPs in different parts of vesicles have been constructed via in situ and ex situ strategies, respectively. Their potential applications have been widely explored, as well. This review presents the progress of block copolymer (BCP) vesicle systems containing different types of NPs including metal NPs, magnetic NPs, and semiconducting quantum dots (QDs), etc. The strategies for controlling the location of NPs within hybrid vesicles are discussed. Typical potential applications of the elegant hybrid vesicles are also highlighted.

Toward enzyme-responsive polymersome drug delivery

In drug delivery, enzyme-responsive drug carriers are becoming increasingly relevant because of the growing association of disease pathology with enzyme overexpression. Polymersomes are of interest to such applications because of their tunable properties. While polymersomes open up a wide range of chemical and physical properties to explore, they also present a challenge in developing generalized rules for the synthesis of novel systems. Motivated by this issue, in this perspective, we summarize the existing knowledge on enzyme-responsive polymersomes and outline the main design choices. Then, we propose heuristics to guide the design of novel systems. Finally, we discuss the potential of an integrated approach using computer simulations and experimental studies to streamline this design process and close the existing knowledge gaps.

Targeted MMP-2 responsive chimeric polymersomes for therapy against colorectal cancer

In the current study, polyethylene glycol (PEG) was linked to polylactide (PLA) through the synthetic peptide PVGLIG which can be selectively cleaved by the tumor-associated matrix metalloproteinase 2 (MMP-2) enzyme. The synthesized chimeric triblock polymer of PEG-b-PVGLIG-PLA was implemented to form nanoscale self-assemble chimeric polymersomes. The hydrophobic SN38 was loaded into polymersomes with 70.3% ± 3.0% encapsulation efficiency demonstrating monodispersed spherical morphologies with 172 ± 30 nm dimension. The prepared chimeric polymersomal formulation provided controlled release of SN38 at physiological condition while illustrating seven-folds higher release rate when exposed to MMP-2 enzyme. At the next stage, AS1411 aptamer was conjugated onto the surface of MMP-2 responsive polymersomal formulation in order to provide guided drug delivery against nucleolin positive cells. In vitro cellular toxicity assay against C26 cell line (nucleolin positive) demonstrated significantly higher toxicity of targeted formulation in comparison with non-targeted one in low SN38 concentrations (0.15-1.25 μg/mL). In vivo study in mice bearing subcutaneous C26 tumor showed higher therapeutic index for MMP-2 responsive chimeric polymersomal formulation of SN38 in comparison with non-responsive one. On the other hand, AS1411 aptamer-targeted MMP-2 responsive chimeric polymersomal formulation exhibited highest therapeutic index compared to other groups. It could be concluded that the targeted chimeric polymersomes bearing both cleavable peptide sequence between their blocks and targeting ligand on their surface, provide favorable characteristics as an ideal delivery system against cancer.

Decoupling copolymer, lipid and carbon nanotube interactions in hybrid, biomimetic vesicles

Bilayer vesicles that mimic a real biological cell can be tailored to carry out a specific function by manipulating the molecular composition of the amphiphiles. These bio-inspired and bio-mimetic structures are increasingly being employed for a number of applications from drug delivery to water purification and beyond. Complex hybrid bilayers are the key building blocks for fully synthetic vesicles that can mimic biological cell membranes, which often contain a wide variety of molecular species. While the assembly and morpholgy of pure phospholid bilayer vesicles is well understood, the functionality and structure dramaticlly changes when copolymer and/or carbon nanotube porins (CNTP) are added. The aim of this study is to understand how the collective molecular interactions within hybrid vesicles affect their nanoscale structure and properties. In situ small and wide angle X-ray scattering (SAXS/WAXS) and molecular dynamics simulations (MD) are used to investigate the morphological effect of molecular interactions between polybutadiene polyethylene oxide, lipids and carbon nanotubes (CNT) within the hybrid vesicle bilayer. Within the lipid/copolymer system, the hybrid bilayer morphology transitions from phase separated lipid and compressed copolymer at low copolymer loadings to a mixed bilayer where opposing lipids are mostly separated from the inner region. This transition begins between 60 wt% and 70 wt%, with full homogenization observed by 80 wt% copolymer. The incorporation of CNT into the hybrid vesicles increases the bilayer thickness and enhances the bilayer symmetry. Analysis of the WAXS and MD indicate that the CNT-dioleoyl interactions are much stronger than the CNT-polybutadiene.

Ring opening polymerization of α-amino acids: advances in synthesis, architecture and applications of polypeptides and their hybrids

This review provides a comprehensive overview of the latest advances in the synthesis, architectural design and biomedical applications of polypeptides and their hybrids.

Physical stimuli-responsive liposomes and polymersomes as drug delivery vehicles based on phase transitions in the membrane

This paper reviews liposomes with crystalline phase and polymersomes exhibiting crystalline and thermotropic liquid crystalline phases in the membrane. Intriguing morphologies of vesicles are described, including spherical, ellipsoidal and faceted vesicles, produced by a large variety of amphiphilic molecules and polymers with nematic phase, smectic phase or crystalline phase. It is highlighted how the phase transitions and the phase grain boundaries could be used ingeniously to destabilize the vesicular structure and to achieve cargo-release under the action of external stimulation. These liposomes and polymersomes are responsive to physical stimuli, such as temperature variation, shear stress, light illumination, and magnetic and electric fields. These stimuli-responsive properties make them promising candidates as new smart drug delivery systems.

Responsive Hybrid (Poly)peptide-Polymer Conjugates

(Poly)peptide-polymer conjugates continue to garner significant interest in the production of functional materials given their composition of natural and synthetic building blocks that confer select and synergistic properties. Owing to opportunities to design predefined architectures and structures with different morphologies, these hybrid conjugates enable new approaches for producing micro- or nanomaterials. Their modular design enables the incorporation of multiple responsive properties into a single conjugate. This review presents recent advances in (poly)peptide-polymer conjugates for drug-delivery applications, with a specific focus on the utility of the (poly)peptide component in the assembly of particles and nanogels, as well as the role of the peptide in triggered drug release.

Drug releasing nanoplatforms activated by alternating magnetic fields

The use of an alternating magnetic field (AMF) to generate non-invasively and spatially a localized heating from a magnetic nano-mediator has become very popular these last years to develop magnetic hyperthermia (MH) as a promising therapeutic modality already used in the clinics. AMF has become highly attractive this last decade over others radiations, as AMF allows a deeper penetration in the body and a less harmful ionizing effect. In addition to pure MH which induces tumor cell death through local T elevation, this AMF-generated magneto-thermal effect can also be exploited as a relevant external stimulus to trigger a drug release from drug-loaded magnetic nanocarriers, temporally and spatially. This review article is focused especially on this concept of AMF induced drug release, possibly combined with MH. The design of such magnetically responsive drug delivery nanoplatforms requires two key and complementary components: a magnetic mediator which collects and turns the magnetic energy into local heat, and a thermoresponsive carrier ensuring thermo-induced drug release, as a consequence of magnetic stimulus. A wide panel of magnetic nanomaterials/chemistries and processes are currently developed to achieve such nanoplatforms. This review article presents a broad overview about the fundamental concepts of drug releasing nanoplatforms activated by AMF, their formulations, and their efficiency in vitro and in vivo. This article is part of a Special Issue entitled "Recent Advances in Bionanomaterials" Guest Editors: Dr. Marie-Louise Saboungi and Dr. Samuel D. Bader.

Synthetic polypeptides: from polymer design to supramolecular assembly and biomedical application

This review highlights the recent advances in the chemical design, supramolecular assembly, and biomedical application of synthetic polypeptides fromN-carboxyanhydrides.

Biodegradable Polyphosphazene Based Peptide-Polymer Hybrids

A novel series of peptide based hybrid polymers designed to undergo enzymatic degradation is presented, via macrosubstitution of a polyphosphazene backbone with the tetrapeptide Gly-Phe-Leu-Gly. Further co-substitution of the hybrid polymers with hydrophilic polyalkylene oxide Jeffamine M-1000 leads to water soluble and biodegradable hybrid polymers. Detailed degradation studies, via ³¹P NMR spectroscopy, dynamic light scattering and field flow fractionation show the polymers degrade via a combination of enzymatic, as well as hydrolytic pathways. The peptide sequence was chosen due to its known property to undergo lysosomal degradation; hence, these degradable, water soluble polymers could be of significant interest for the use as polymer therapeutics. In this context, we investigated conjugation of the immune response modifier imiquimod to the polymers via the tetrapeptide and report the self-assembly behavior of the conjugate, as well as its enzymatically triggered drug release behavior.

Hybrid Vesicles with Alterable Fully Covered Armors of Nanoparticles: Fabrication, Catalysis, and Surface-Enhanced Raman Scattering

This work reports on the facile preparation of hybrid polymer vesicles with alterable armors of metal nanoparticles by using a novel hyperbranched polymer vesicle as the templates. The vesicles were prepared through the aqueous self-assembly of a hyperbranched multiarm copolymers with many tertiary amino groups on the surface, which can electrostatically complexed or coordinated with metal ions like AuCl4(-), PtCl6(2-), and Ag(+) ions. Subsequently, the vesicles coated with metal ions can be in situ reduced into metal nanoparticles, through which a series of surface-engineered vesicles (Au@vesicles, Ag@vesicles, Pt@vesicles) with an advantage of fully covered metal nanoparticles on the surface could be readily prepared. The morphologies, structures, and formation mechanism of the as-prepared hybrid vesicles were carefully characterized, and the obtained hybrid vesicles also showed great potentials in catalysis and surface-enhanced Raman scattering (SERS) applications.

Poly(trimethylene carbonate)-based polymers engineered for biodegradable functional biomaterials

This review presents recent examples of applications and functionalization strategies of poly(trimethylene carbonate), its copolymers, and its derivatives to exploit the unique physicochemical properties of the aliphatic polycarbonate backbone.

Bioinspired polymer vesicles and membranes for biological and medical applications

Biological membranes play an essential role in living organisms by providing stable and functional compartments, supporting signalling and selective transport. Combining synthetic polymer membranes with biological molecules promises to be an effective strategy to mimic the functions of cell membranes and apply them in artificial systems.