Reduction-Triggered Transformation of Disulfide-Containing Micelles at Chemically Tunable Rates

Nitric Oxide (NO)-Releasing Macromolecules: Rational Design and Biomedical Applications

Nitric oxide (NO) has been recognized as a ubiquitous gaseous transmitter and the therapeutic potential has nowadays received increasing interest. However, NO cannot be easily directly administered due to its high reactivity in air and high concentration-dependent physiological roles. As such, a plethora of NO donors have been developed that can reversibly store and release NO under specific conditions. To enhance the stability and modulate the NO release profiles, small molecule-based NO donors were covalently linked to polymeric scaffolds, rendering them with multifunctional integration, prolonged release durations, and optimized therapeutic outcomes. In this minireview, we highlight the recent achievements of NO-releasing macromolecules in terms of chemical design and biomedical applications. We hope that more efforts could be devoted to this emerging yet promising field.

Quantitative and high drug loading of self-assembled prodrug with defined molecular structures for effective cancer therapy

Nanomedicines have made significant progress in the delivery of small molecular drugs, many challenges, however, still remain to be overcome, such as unsatisfactory drug loading, formulation instability, premature drug leakage, and poor blood circulation. Herein, an innovative glutathione (GSH)-sensitive amphiphilic dendritic prodrug with quantitative and high drug loading (>30 wt%) is reported. The multi-armed structure of prepared prodrug can self-assemble into nanoparticles in aqueous solution without the introduction of any organic solvents. The self-assembled prodrug nanoparticle is composed of the following key components: (i) polyethylene glycol (PEG) outer shell ensuring biocompatibility and prolonging blood circulation, (ii) prodrug inner core responding to GSH for triggered release of intact drug, (iii) multi-armed dendritic structure facilitating self-assembly and enhancing drug loading content, (iv) covalent drug conjugation avoiding drug leakage and improving stability, (v) defined chemical structures and quantitative drug loading easy for reproduction. Both in vitro and in vivo results show that these GSH-responsive prodrug nanoparticle exhibits significant inhibition of tumor cell growth, and is promising for efficient and safe chemotherapeutic delivery.

Supramolecular peptide constructed by molecular Lego allowing programmable self-assembly for photodynamic therapy

Peptide self-assemblies with multiple nanostructures have great potentials in functional biomaterials, and yet the tedious and costly covalent peptide modification and the lack of facile controllability on self-assembly morphology retard the peptide-related exploration. Here we report a simple approach to fabricate a supramolecular peptide that shows programmable self-assembly with multiple morphologies and application in photodynamic therapy. Pillar[5]arene-based host-guest recognition is used to construct a supramolecular peptide, which simplify the peptide modification and promote the controllability of the self-assembly behavior. Due to the ERGDS sequences on the exterior surfaces and hydrophobic cores of self-assemblies, the nanoparticles formed from the supramolecular peptide are suitable vehicles to encapsulate a photosensitizer for photodynamic therapy. In vitro and in vivo studies demonstrate that the inherent targeting capability and supramolecular strategy greatly boost its photodynamic therapeutic efficiency. This supramolecular peptide holds promising potentials in precise cancer therapy and perspectives for the peptide modification.

Synergistic self-seeding in one-dimension: a route to patchy and block comicelles with uniform and controllable length

By manipulating both the dissolution sequence of polymer crystallites and the growth rate of polymer unimers, patchy comicelles and block comicelles with uniform and controllable length can be obtained.

Self-seeding is a process unique to polymer crystals, which consist of regions of different chain packing order and different crystallinity. Here we report the synergistic self-seeding behaviour of pairs of core-crystalline block copolymer (BCP) micelle fragments and show how this strategy can be employed to control the morphology of these BCP comicelles. Each micelle fragment has a critical dissolution temperature (T_c), and unimers of each BCP have a characteristic epitaxial growth rate. The T_c value affects the dissolution sequence of the fragments upon heating, while the unimer growth rate affects the growth sequence upon cooling. By carefully choosing micelle fragments having different T_c values as well as growth rates, we could prepare patchy comicelles and block comicelles with uniform and controllable length. This synergistic self-seeding strategy is a simple yet effective route to control both length and morphology of core-crystalline comicelles

Synthesis and self-seeding behavior of oligo(p-phenylene vinylene)-b-poly(N-(2-hydroxypropyl)methacrylamide)

This article reports the preparation of uniform fiber- and ribbon-like nanostructures via the self-seeding of OPV₅-b-PHPMA diblock copolymers.

pH-Responsive polyelectrolyte coated gadolinium oxide-doped mesoporous silica nanoparticles (Gd2O3@MSNs) for synergistic drug delivery and magnetic resonance imaging enhancement

Theranostic platforms that combine therapeutic and imaging modalities have received increasing interest.

Disassembly and tumor-targeting drug delivery of reduction-responsive degradable block copolymer nanoassemblies

Review on recent strategies to synthesize novel disulfide-containing reductively-degradable block copolymers and their nanoassemblies as being classified with the number, position, and location of the disulfide linkages toward effective tumor-targeting intracellular drug delivery exhibiting enhanced release of encapsulated drugs.

Poly(ethylene glycol) brush-b-poly(N-vinylpyrrolidone)-based double hydrophilic block copolymer particles crosslinked via crystalline α-cyclodextrin domains

Self-assembly of block copolymers is a significant area of polymer science. The self-assembly of completely water-soluble block copolymers is of particular interest, albeit a challenging task. In the present work the self-assembly of a linear-brush architecture block copolymer, namely poly(N-vinylpyrrolidone)-b-poly(oligoethylene glycol methacrylate) (PVP-b-POEGMA), in water is studied. Moreover, the assembled structures are crosslinked via α-CD host/guest complexation in a supramolecular way. The crosslinking shifts the equilibrium toward aggregate formation without switching off the dynamic equilibrium of double hydrophilic block copolymer (DHBC). As a consequence, the self-assembly efficiency is improved without extinguishing the unique DHBC self-assembly behavior. In addition, decrosslinking could be induced without a change in concentration by adding a competing complexation agent for α-CD. The self-assembly behavior was followed by DLS measurement, while the presence of the particles could be observed via cryo-TEM before and after crosslinking.

Self-assembly of the double hydrophilic block copolymer poly(N-vinylpyrrolidone)-b-poly(oligoethylene glycol methacrylate) and supramolecular crosslinking via α-cyclodextrin in water is presented.

Photo-induced hydrogen-bonding complexes for drug periodic release

A convenient approach for periodic drug release was accomplished through photo-induced hydrogen-bonding complexation, and then by further disruption upon heating.

Emerging Applications of Fluorogenic and Non-fluorogenic Bifunctional Linkers

Homo- and hetero-bifunctional linkers play vital roles in constructing a variety of functional systems, ranging from protein bioconjugates with drugs and functional agents, to surface modification of nanoparticles and living cells, and to the cyclization/dimerization of synthetic polymers and biomolecules. Conventional approaches for assaying conjugation extents typically rely on ex situ techniques, such as mass spectrometry, gel electrophoresis, and size-exclusion chromatography. If the conjugation process involving bifunctional linkers was rendered fluorogenic, then in situ monitoring, quantification, and optical tracking/visualization of relevant processes would be achieved. In this review, conventional non-fluorogenic linkers are first discussed. Then the focus is on the evolution and emerging applications of fluorogenic bifunctional linkers, which are categorized into hetero-bifunctional single-caging fluorogenic linkers, homo-bifunctional double-caging fluorogenic linkers, and hetero-bifunctional double-caging fluorogenic linkers. In addition, stimuli-cleavable bifunctional linkers designed for both conjugation and subsequent site-specific triggered release are also summarized.

Construction of Small-Sized, Robust, and Reduction-Responsive Polypeptide Micelles for High Loading and Targeted Delivery of Chemotherapeutics

Polypeptide micelles, though having been proved to be an appealing nanoplatform for cancer chemotherapy, are met with issues like inefficient drug encapsulation, gradual drug release, and low tumor cell selectivity and uptake. Here, we report on cRGD-decorated, small-sized, robust, and reduction-responsive polytyrosine micelles (cRGD-rPTM) based on poly(ethylene glycol)- b-poly(l-tyrosine)-lipoic acid (PEG- b-PTyr-LA) conjugate for high loading and targeted delivery of doxorubicin (Dox). Notably, cRGD-rPTM exhibited efficient loading of Dox, giving cRGD-rPTM-Dox with a drug loading content (DLC) of 18.5 wt % and a small size of 45 nm at a theoretical DLC of 20 wt %. cRGD-rPTM-Dox displayed reduction-triggered drug release, high selectivity and superior antiproliferative activity toward α_vβ₃ integrin positive MDA-MB-231 breast cancer cells (IC₅₀ = 1.5 μg/mL) to both nontargeted rPTM-Dox and clinical liposomal formulation (LP-Dox). cRGD-rPTM-Dox demonstrated a prolonged circulation time compared with the noncrosslinked cRGD-PTM-Dox control and significantly better accumulation in MDA-MB-231 breast tumor xenografts than nontargeted rPTM-Dox. Moreover, cRGD-rPTM-Dox at 6 mg Dox equiv/kg could remarkably suppress growth of MDA-MB-231 human breast tumor without inducing obvious side effects, outperforming both rPTM-Dox and LP-Dox. These reduction-responsive multifunctional polytyrosine micelles appear to be a viable and versatile nanoplatform for targeted chemotherapy.