Polymersome Membrane Engineering with Active Targeting or Controlled Permeability for Responsive Drug Delivery

Polymersomes have been extensively investigated for drug delivery as nanocarriers for two decades due to a series of advantages including high stability under physiological conditions, simultaneous encapsulation of hydrophilic and hydrophobic drugs inside inner cavities and membranes, respectively, and facile adjustment of membrane and surface properties, as well as controlled drug release through incorporation of stimuli-responsive components. Despite these features, polymersome nanocarriers frequently suffer from nontargeting delivery and poor membrane permeability. In recent years, polymersomes have been functionalized for more efficient drug delivery. The surface shells were explored to be modified with diverse active targeting groups to improve disease-targeting delivery. The membrane permeability of the polymersomes was adjusted by incorporation of the stimuli-responsive components for smart controlled transportation of the encapsulated drugs. Therefore, being the polymersome-biointerface, tailorable properties can be introduced by its carefully modulated engineering. This review elaborates on the role of polymersome membranes as a platform to incorporate versatile features. First, we discuss how surface functionalization facilitates the directional journey to the targeting sites toward specific diseases, cells, or intracellular organelles via active targeting. Moreover, recent advances in the past decade related to membrane permeability to control drug release are also summarized. We finally discuss future development to promote polymersomes as in vivo drug delivery nanocarriers.

Production of Minor Ginsenoside CK from Major Ginsenosides by Biotransformation and Its Advances in Targeted Delivery to Tumor Tissues Using Nanoformulations

For over 2000 years, ginseng (roots of Panax ginseng C.A. Meyer) has been used as a traditional herbal medicine. Ginsenosides are bioactive compounds present in ginseng responsible for the pharmacological effects and curing various acute diseases as well as chronic diseases including cardiovascular disease, cancer and diabetes. Structurally, ginsenosides consist of a hydrophobic aglycone moiety fused with one to four hydrophilic glycoside moieties. Based on the position of sugar units and their abundance, ginsenosides are classified into major and minor ginsenosides. Despite the great potential of ginsenosides, major ginsenosides are poorly absorbed in the blood circulation, resulting in poor bioavailability. Interestingly, owing to their small molecular weight, minor ginsenosides exhibit good permeability across cell membranes and bioavailability. However, extremely small quantities of minor ginsenosides extracted from ginseng plants cannot fulfill the requirement of scientific and clinical studies. Therefore, the production of minor ginsenosides in mass production is a topic of interest. In addition, their poor solubility and lack of targetability to tumor tissues limits their application in cancer therapy. In this review, various methods used for the transformation of major ginsenosides to minor ginsenoside compound K (CK) are summarized. For the production of CK, various transformation methods apply to major ginsenosides. The challenges present in these transformations and future research directions for producing bulk quantities of minor ginsenosides are discussed. Furthermore, attention is also paid to the utilization of nanoformulation technology to improve the bioavailability of minor ginsenoside CK.

Polymeric Nanoparticle Based Diagnosis and Nanomedicine for Treatment and Development of Vaccines for Cerebral Malaria: A Review on Recent Advancement

Cerebral malaria occurs due to Plasmodium falciparum infection, which causes 228 million infections and 450,000 deaths worldwide every year. African people are mostly affected with nearly 91% cases, of which 86% are pregnant women and infants. India and Brazil are the other two countries severely suffering from malaria endemicity. Commonly used drugs have severe side effects, and unfortunately no suitable vaccine is available in the market today. In this line, this review is focused on polymeric nanomaterials and nanocapsules that can be used for the development of effective diagnostic strategies, nanomedicines, and vaccines in the management of cerebral malaria. Further, this review will help scientists and medical professionals by updating the status on the development stages of polymeric nanoparticle based diagnostics, nanomedicines, and vaccines and strategies to eradicate cerebral malaria. In addition to this, the predominant focus of this review is antimalarial agents based on polymer nanomedicines that are currently in the preclinical and clinical trial stages, and potential developments are suggested as well. This review further will have an important social and commercial impact worldwide for the development of polymeric nanomedicines and strategies for the treatment of cerebral malaria.

ATN-161 Peptide Functionalized Reversibly Cross-Linked Polymersomes Mediate Targeted Doxorubicin Delivery into Melanoma-Bearing C57BL/6 Mice

PHSCN peptide (licensed as ATN-161) is an effective α₅β₁ integrin inhibitor that has advanced to phase II clinical trials to treat solid tumors. Here we developed ATN-161 functionalized self-cross-linkable and intracellularly de-cross-linkable polymersomes (ATN/SCID-Ps) for highly efficient and targeted delivery of doxorubicin hydrochloride (DOX·HCl) into B16F10 melanoma-bearing C57BL/6 mice. ATN/SCID-Ps exhibited a high loading capacity of DOX·HCl. The size of DOX-loaded ATN/SCID-Ps (DOX-ATN/SCID-Ps) decreased from 150 to 88 nm with increasing ATN surface densities from 0 to 100% (mol/mol). DOX-ATN/SCID-Ps were robust with low drug leakage under physiological conditions while quickly releasing DOX with the addition of 10 mM glutathione. MTT assay results displayed that DOX-ATN/SCID-Ps induced ATN density-dependent antitumor activity to α₅β₁ integrin overexpressing B16F10 melanoma cells, in which 56% ATN-161 was optimal. Flow cytometry and CLSM studies revealed significantly more efficient internalization and cytoplasmic DOX release in B16F10 cells for DOX-ATN/SCID-Ps than for DOX-SCID-Ps (nontargeting control) as well as clinically used pegylated liposomal doxorubicin (DOX-LPs). DOX-ATN/SCID-Ps displayed a long blood circulation time (elimination half-life = 4.13 h) and 4 times higher DOX accumulation in B16F10 bearing C57BL/6 mice than DOX-LPs. Interestingly, DOX-ATN/SCID-Ps exhibited a superior maximum-tolerated dose of over 100 mg DOX·HCl/kg, 10 times higher than DOX-LPs. Remarkably, DOX-ATN/SCID-Ps could significantly inhibit the growth of aggressive B16F10 melanoma with little adverse effects via either multiple or single injection of total dosage of 100 mg DOX·HCl/kg, resulting in greatly improved survival rates as compared to DOX-LPs. ATN/SCID-Ps are appealing nanovehicles for targeted chemotherapy of α₅β₁ integrin positive solid tumors.

An amphiphilic graft copolymer-based nanoparticle platform for reduction-responsive anticancer and antimalarial drug delivery

Medical applications of anticancer and antimalarial drugs often suffer from low aqueous solubility, high systemic toxicity, and metabolic instability. Smart nanocarrier-based drug delivery systems provide means of solving these problems at once. Herein, we present such a smart nanoparticle platform based on self-assembled, reduction-responsive amphiphilic graft copolymers, which were successfully synthesized through thiol-disulfide exchange reaction between thiolated hydrophilic block and pyridyl disulfide functionalized hydrophobic block. These amphiphilic graft copolymers self-assembled into nanoparticles with mean diameters of about 30-50 nm and readily incorporated hydrophobic guest molecules. Fluorescence correlation spectroscopy (FCS) was used to study nanoparticle stability and triggered release of a model compound in detail. Long-term colloidal stability and model compound retention within the nanoparticles was found when analyzed in cell media at body temperature. In contrast, rapid, complete reduction-triggered disassembly and model compound release was achieved within a physiological reducing environment. The synthesized copolymers revealed no intrinsic cellular toxicity up to 1 mg mL(-1). Drug-loaded reduction-sensitive nanoparticles delivered a hydrophobic model anticancer drug (doxorubicin, DOX) to cancer cells (HeLa cells) and an experimental, metabolically unstable antimalarial drug (the serine hydroxymethyltransferase (SHMT) inhibitor (±)-1) to Plasmodium falciparum-infected red blood cells (iRBCs), with higher efficacy compared to similar, non-sensitive drug-loaded nanoparticles. These responsive copolymer-based nanoparticles represent a promising candidate as smart nanocarrier platform for various drugs to be applied to different diseases, due to the biocompatibility and biodegradability of the hydrophobic block, and the protein-repellent hydrophilic block.

Expansile crosslinked polymersomes for pH sensitive delivery of doxorubicin

We report a new crosslinked polymersome with pH-responsive swelling properties through acidic hydrolysis of hydrophobic contents from the amphiphilic polymer chains. Its unique stability under physiological conditions and large swelling capability under low pH conditions give this polymersome promising potential for anticancer drug delivery.

Construction of redox/pH dual stimuli-responsive PEGylated polymeric micelles for intracellular doxorubicin delivery in liver cancer

A schematic of the complete process of DOX-loaded mPEG-SS-PNLG micelles uptake into tumor cells and intracellular release of DOX; size distribution of mPEG-SS-PNLG (90%) micelles and in vivo antitumor efficacy.

Hypoxia-responsive nanocarriers for cancer imaging and therapy: recent approaches and future perspectives

This review focuses on hypoxia-responsive nanocarriers, which can be disintegrated by recognizing the hypoxic microenvironment of cancer cells, and their utilization in cancer imaging and therapy.

Stimuli-responsive polymersomes for cancer therapy

This review focuses on stimuli-responsive polymersomes for cancer therapy, which can be disintegrated by recognizing the specific environments of cancer (e.g., low pH, bioreductive environment, over-expressed enzymes,etc.).

Pancreatic cancer therapy using an injectable nanobiohybrid hydrogel

Nanobiohybrid hydrogels, composed of biocompatible inorganic nanoparticles and biodegradable polymeric hydrogels, have been developed as the sustained delivery carrier of gemcitabine for the treatment of pancreatic cancer.

Fabricated Elastin

The mechanical stability, elasticity, inherent bioactivity, and self-assembly properties of elastin make it a highly attractive candidate for the fabrication of versatile biomaterials. The ability to engineer specific peptide sequences derived from elastin allows the precise control of these physicochemical and organizational characteristics, and further broadens the diversity of elastin-based applications. Elastin and elastin-like peptides can also be modified or blended with other natural or synthetic moieties, including peptides, proteins, polysaccharides, and polymers, to augment existing capabilities or confer additional architectural and biofunctional features to compositionally pure materials. Elastin and elastin-based composites have been subjected to diverse fabrication processes, including heating, electrospinning, wet spinning, solvent casting, freeze-drying, and cross-linking, for the manufacture of particles, fibers, gels, tubes, sheets and films. The resulting materials can be tailored to possess specific strength, elasticity, morphology, topography, porosity, wettability, surface charge, and bioactivity. This extraordinary tunability of elastin-based constructs enables their use in a range of biomedical and tissue engineering applications such as targeted drug delivery, cell encapsulation, vascular repair, nerve regeneration, wound healing, and dermal, cartilage, bone, and dental replacement.

Polyurethane foam containing rhEGF as a dressing material for healing diabetic wounds: Synthesis, characterization, in vitro and in vivo studies

Diabetic wounds are a major health issue associated with diabetes mellitus. To surmount this issue, we developed polyurethane foams (PUFs) incorporating varying amounts of recombinant human epidermal growth factor (rhEGF) (rhEGF-PUFs) as a wound dressing for diabetic wounds. From electron microscopy images, it was found that the pore size of the rhEGF-PUFs surface (the wound contact layer) was less than 100μm, regardless of rhEGF content. The release of rhEGF from the PUFs was evaluated using an enzyme-linked immunosorbent assay. The result showed that the release of rhEGF was time and concentration dependent, i.e., the amount of released rhEGF significantly increased as the immersion time and the rhEGF content of the PUFs increased. In vitro cytotoxicity testing showed that rhEGF-PUFs increased the viability of HaCaT human keratinocytes and CCD986-sk human fibroblasts, which indicated that the incorporated rhEGF maintained its biological activity. In an in vitro scratch wound healing assay, the wound closure rate was faster in CCD986-sk human fibroblasts than in HaCaT human keratinocytes. Finally, the rhEGF-PUFs were evaluated as an in vivo treatment in a full-thickness wound model in diabetized Sprague-Dawley rats. The result indicated that compared with PUFs, rhEGF-PUFs accelerated wound healing by promoting wound contraction, re-epithelialization, collagen deposition and the formation of a skin appendage. These findings demonstrate that rhEGF-PUFs are a promising dressing for diabetic wounds.

Heparin-based temperature-sensitive injectable hydrogels for protein delivery

Polysaccharide-based biodegradable, biocompatible and temperature-sensitive injectable hydrogels have been developed for the sustained delivery of proteins.

Recent progress in designing shell cross-linked polymer capsules for drug delivery

This tutorial review highlights the progress made during recent years in the development of the shell cross-linked (SCL) polymer nanocapsules and the impact of the most important scientific ideas on this field of knowledge.

Evaluation of AgHAP-containing polyurethane foam dressing for wound healing: synthesis, characterization, in vitro and in vivo studies

Silver-substituted hydroxyapatite containing polyurethane foams were developed to control wound infection.