Galactose-Decorated Reduction-Sensitive Degradable Chimaeric Polymersomes as a Multifunctional Nanocarrier To Efficiently Chaperone Apoptotic Proteins into Hepatoma Cells

Hepatoma-targeting reduction-sensitive chimaeric biodegradable polymersomes were designed and developed based on galactose–poly­(ethylene glycol)–poly­(ε-caprolactone) (Gal-PEG-PCL), PEG–PCL–poly­(2-(diethylamino)­ethyl methacrylate) (PEG-PCL-PDEA, asymmetric), and PEG-SS-PCL for facile loading and triggered intracellular delivery of proteins. The chimaeric polymersomes formed from PEG-PCL-PDEA and PEG-SS-PCL had a monodisperse distribution with average sizes ranging from 95.5 to 199.2 nm depending on PEG-SS-PCL contents. Notably, these polymersomes displayed decent loading of bovine serum albumin (BSA), ovalbumin (OVA), and cytochrome C (CC) proteins likely due to presence of electrostatic and hydrogen bonding interactions between proteins and PDEA block located in the interior of polymersomes. The <i>in vitro</i> release studies showed that protein release was largely accelerated under a reductive condition containing 10 mM dithiothreitol (DTT). For example, ca. 77.2 and 22.1% of FITC-BSA were released from CP­(SS50) (chimaeric polymersomes containing 50 wt % PEG-SS-PCL) at 37 °C in 12 h in the presence and absence of 10 mM DTT, respectively. Confocal microscopy showed that FITC-CC-loaded Gal-decorated CP­(SS40) could efficiently deliver and release FITC-CC into HepG2 cells following 24 h treatment, in contrast to little or negligible fluorescence detected in HepG2 cells treated with FITC-CC-loaded nontargeting polymersomes or free CC. MTT assays revealed that CC-loaded Gal-decorated CP­(SS40) exhibited apparent targetability and pronounced antitumor activity to HepG2 cells, in which cell viabilities decreased from 81.9, 60.6, 49.5, 42.2 to 31.5% with increasing Gal-PEG-PCL contents from 0, 10, 20, 30 to 40 wt %. Most remarkably, granzyme B-loaded Gal-decorated chimaeric polymersomes effectively caused apoptosis of HepG2 cells with a markedly low half-maximal inhibitory concentration (IC₅₀) of 2.7 nM. These reduction-responsive chimaeric biodegradable polymersomes offer a multifunctional platform for efficient intracellular protein delivery

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)-<i>b</i>-poly­(l-tyrosine)-lipoic acid (PEG-<i>b</i>-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

Hyaluronic Acid-Shelled Disulfide-Cross-Linked Nanopolymersomes for Ultrahigh-Efficiency Reactive Encapsulation and CD44-Targeted Delivery of Mertansine Toxin

It was and remains a big challenge for cancer nanomedicines to achieve high and stable drug loading with fast drug release in the target cells. Here, we report on novel hyaluronic acid-shelled disulfide-cross-linked biodegradable polymersomes (HA-XPS) self-assembled from hyaluronic acid-<i>b</i>-poly­(trimethylene carbonate-<i>co</i>-dithiolane trimethylene carbonate) diblock copolymer for ultrahigh-efficiency reactive encapsulation and CD44-targeted delivery of mertansine (DM1) toxin, a highly potent warhead for clinically used antibody-drug conjugates. Remarkably, HA-XPS showed quantitative encapsulation of DM1 even with a high drug loading content of 16.7 wt %. DM1-loaded HA-XPS (HA-XPS-DM1) presented a small size of ∼80 nm, low drug leakage under physiological conditions, and fast glutathione-triggered drug release. MTT assays revealed that HA-XPS was noncytotoxic while HA-XPS-DM1 was highly potent to MDA-MB-231 cells with an IC₅₀ comparable to that of free DM1. The in vitro and in vivo inhibition experiments indicated that HA-XPS could actively target MDA-MB-231 cells. Notably, HA-XPS-DM1 while causing little adverse effect could effectively inhibit tumor growth and significantly prolong survival time in MDA-MB-231 human breast tumor-bearing mice. HA-XPS-DM1 provides a novel and unique treatment for CD44-positive cancers

Glutathione-Sensitive Hyaluronic Acid-Mercaptopurine Prodrug Linked via Carbonyl Vinyl Sulfide: A Robust and CD44-Targeted Nanomedicine for Leukemia

6-Mercaptopurine (6-MP) is an essential medicine used for treating leukemia in the clinics. 6-MP suffers, however, from poor water solubility, low bioavailability, and significant side effects. Here, we designed CD44-targeted glutathione-sensitive hyaluronic acid-mercaptopurine prodrug (HA-GS-MP) linked via carbonyl vinyl sulfide for safer and enhanced treatment of acute myeloid leukemia (AML). HA-GS-MP obtained with 50 kDa HA and 6-MP conjugation content of 6.9 wt % showed excellent water solubility with a hydrodynamic size of ca. 15 nm. Intriguingly, HA-GS-MP was extremely stable, without any drug leakage, under physiological environment while rapidly releasing 6-MP in response to 10 mM glutathione. HA-GS-MP exhibited obvious targetability and markedly enhanced antitumor effect to OCI/AML-2 human AML cells (IC₅₀ = 16.9 μg 6-MP equiv./mL). The pharmacokinetic studies displayed that Cy5-labeled HA-GS-MP had a long circulation time in mice (elimination half-life = 4.37 h). The in vivo fluorescence images demonstrated strong and persistent accumulation of Cy5-labeled HA-GS-MP from 4 to 48 h post injection in the subcutaneous OCI/AML-2 tumor in nude mice. Notably, HA-GS-MP while causing little side effects induced significantly enhanced growth inhibition of OCI/AML-2 tumor and better survival rate of OCI/AML-2 tumor-bearing mice as compared to free 6-MP. Carbonyl vinyl sulfide-linked hyaluronic acid-mercaptopurine prodrug has appeared to be a simple and smart nanomedicine for targeted treatment of AML

Structure Governs the Deformability of Polymer Particles in a Microfluidic Blood Capillary Model

Particle stiffness is a design parameter that affects bionano interactions, including biodistribution kinetics and cellular processing. Herein, we develop soft polysaccharide (hyaluronic acid, HA) replica particles and capsules with tunable stiffness and sizes similar to human red blood cells (RBCs) via atom transfer radical polymerization-mediated continuous assembly of polymers (CAP_ATRP) and investigate their stiffness and deformability using colloidal-probe atomic force microscopy (CP-AFM) and a microfluidic blood capillary model, respectively. We demonstrate that HA replica particles and capsules with comparable nanoscale stiffness exhibit significantly different behaviors in a microfluidic blood capillary model. HA capsules behaved as RBCs, while HA replica particles had difficulty passing through the capillaries. These results (i) demonstrate how flow-based deformability measurements can be used to complement nanoscale stiffness measurements and (ii) provide important insight into the role of particle structure on the flow-based deformability of soft replica particles and capsules in a physiologically relevant microfluidic model

Tuning the Properties of Polymer Capsules for Cellular Interactions

Particle–cell interactions are governed by, among other factors, the composition and surface properties of the particles. Herein, we report the preparation of various polymer capsules with different compositions and properties via atom transfer radical polymerization mediated continuous assembly of polymers (CAP_ATRP), where the cellular interactions of these capsules, particularly fouling and specific targeting, are examined by flow cytometry and deconvolution microscopy. Acrylated eight-arm poly­(ethylene glycol) (8-PEG) and poly­(<i>N</i>-(2-hydroxypropyl)-methacrylamide) (PHPMA) as well as methacrylated hyaluronic acid (HA), poly­(glutamic acid) (PGA), and poly­(methacrylic acid) (PMA) are used as macro-cross-linkers to obtain a range of polymer capsules with different compositions (PEG, PHPMA, HA, PGA, and PMA). Capsules composed of low-fouling polymers, PEG and PHPMA, show negligible association with macrophage Raw 264.7, monocyte THP-1, and HeLa cells. HA capsules, although moderately low-fouling (<22%) to HeLa, BT474, Raw 264.7, and THP-1 cells, exhibit high targeting specificity to CD44-over-expressing MDA-MB-231 cells. In contrast, PGA and PMA capsules show high cellular association toward phagocytic Raw 264.7 and THP-1 cells. These findings demonstrate the capability of the CAP_ATRP technique in preparing polymer capsules with specific cellular interactions

Templated Polymer Replica Nanoparticles to Facilitate Assessment of Material-Dependent Pharmacokinetics and Biodistribution

Surface modification is frequently used to tailor the interactions of nanoparticles with biological systems. In many cases, the chemical nature of the treatments employed to modify the biological interface (for example attachment of hydrophilic polymers or targeting groups) is the focus of attention. However, isolation of the fundamental effects of the materials employed to modify the interface are often confounded by secondary effects imparted by the underlying substrate. Herein, we demonstrate that polymer replica particles templated from degradable mesoporous silica provide a facile means to evaluate the impact of surface modification on the biological interactions of nanomaterials, independent of the substrate. Poly­(ethylene glycol) (PEG), poly­(<i>N</i>-(2 hydroxypropyl)­methacrylamide) (PHPMA), and poly­(methacrylic acid) (PMA) were templated onto mesoporous silica and cross-linked and the residual particles were removed. The resulting nanoparticles, comprising interfacial polymer alone, were then investigated using a range of in vitro and in vivo tests. As expected, the PEG particles showed the best stealth properties, and these trends were consistent in both in vitro and in vivo studies. PMA particles showed the highest cell association in cell lines in vitro and were rapidly taken up by monocytes in ex vivo whole blood, properties consistent with the very high in vivo clearance subsequently seen in rats. In contrast, PHPMA particles showed rapid association with both granulocytes and monocytes in ex vivo whole blood, even though in vivo clearance was less rapid than the PMA particles. Rat studies confirmed better systemic exposure for PEG and PHPMA particles when compared to PMA particles. This study provides a new avenue for investigating material-dependent biological behaviors of polymer particles, irrespective of the properties of the underlying core, and provides insights for the selection of polymer particles for future biological applications

Engineered Metal-Phenolic Capsules Show Tunable Targeted Delivery to Cancer Cells

We engineered metal-phenolic capsules with both high targeting and low nonspecific cell binding properties. The capsules were prepared by coating phenolic-functionalized hyaluronic acid (HA) and poly­(ethylene glycol) (PEG) on calcium carbonate templates, followed by cross-linking the phenolic groups with metal ions and removing the templates. The incorporation of HA significantly enhanced binding and association with a CD44 overexpressing (CD44+) cancer cell line, while the incorporation of PEG reduced nonspecific interactions with a CD44 minimal-expressing (CD44−) cell line. Moreover, high specific targeting to CD44+ cells can be balanced with low nonspecific binding to CD44– cells simply by using an optimized feed-ratio of HA and PEG to vary the content of HA and PEG incorporated into the capsules. Loading an anticancer drug (i.e., doxorubicin) into the obtained capsules resulted in significantly higher cytotoxicity to CD44+ cells but lower cytotoxicity to CD44– cells