Biopolymer Nanovehicles for Oral Delivery of Natural Anticancer Agents

Cancer is the second leading cause of death throughout the world. Nature-inspired anticancer agents (NAAs) that are a gift of nature to humanity have been extensively utilized in the alleviation/prevention of the disease due to their numerous pharmacological activities. While the oral route is an ideal and common way of drug administration, the application of NAAs through the oral pathway has been extremely limited owing to their inherent features, e.g., poor solubility, gastrointestinal (GI) instability, and low bioavailability. With the development of nano-driven encapsulation strategies, polymeric vehicles, especially those with natural origins, have demonstrated a potent platform, which can professionally shield versatile NAAs against GI barricades and safely deliver them to the site of action. In this review, the predicament of orally delivering NAAs and the encapsulation strategy solutions based on biopolymer matrices are summarized. Proof-of-concept in vitro/in vivo results are also discussed for oral delivery of these agents by various biopolymer vehicles, which can be found so far from the literature. Last but not the least, the challenges and new opportunities in the field are highlighted.     

Plant‐Based Hollow Microcapsules for Oral Delivery Applications: Toward Optimized Loading and Controlled Release

Efficient oral administration of protein‐based therapeutics faces significant challenges due to degradation from the highly acidic conditions present in the stomach and proteases present in the digestive tract. Herein, investigations into spike‐covered sunflower sporopollenin exine capsules (SECs) for oral protein delivery using bovine serum albumin (BSA) as a model drug are reported and provide significant insights into the optimization of SEC extraction, SEC loading, and controlled release. The phosphoric‐acid‐based SEC extraction process is optimized. Compound loading is shown to be driven by the evacuation of air bubbles from SEC cavities through the porous SEC shell wall, and vacuum loading is shown to be the optimal loading method. Three initial BSA‐loading proportions are evaluated, leading to a practical loading efficiency of 22.3 ± 1.5 wt% and the determination that the theoretical maximum loading is 46.4 ± 2.5 wt%. Finally, an oral delivery formulation for targeted intestinal delivery is developed by tableting BSA‐loaded SECs and enteric coating. BSA release is inhibited for 2 h in simulated gastric conditions followed by 100% release within 8 h in simulated intestinal conditions. Collectively, these results indicate that sunflower SECs provide a versatile platform for the oral delivery of therapeutics.     

A Versatile Platform for the Tumor-Targeted Intracellular Delivery of Peptides,Proteins, and siRNA

The efficient delivery of biologics into cells provide unique opportunities to modulate intracellular targets not druggable by conventional small molecules. The supercharged polypeptide (SCP) has become a novel intracellular delivery system due to their special advantages, including enhanced delivery efficiency and serum tolerance. However, owing to their cationic charge and non-specificity characteristics, the in vivo application of SCP is limited. Here, an activatable SCP (ASCP) with a pH-sensitive charge shielding sequence (CSS), a protease cleavage site, and SCP are engineered. This system shows the potential to reduce the non-specific binding and effectively deliver various cargo (peptide, protein, small molecule, and siRNA) into the cytosol not only in vitro but also in vivo. Furthermore, an ASCP fusion protein is designed to co-delivery of peptide (KLA)/siRNA (IKBKE) with different tumorigenesis pathways to triple negative breast cancer (TNBC) for optimal therapeutic outcomes. It is believed that ASCP delivery system will facilitate the development of bioactive molecules for use against intracellular targets. This simple yet versatile delivery system can also pave the way for the co-delivery of multiple therapeutic cargos to address the emerging needs of combination cancer therapy.     

Phase‐Changeable Nanoemulsions for Oral Delivery of a Therapeutic Peptide: Toward Targeting the Pancreas for Antidiabetic Treatments Using Lymphatic Transport

The oral absorption of a therapeutic peptide (such as exenatide; EXT) that can improve glycemic control in the treatment of type 2 diabetes is limited by multiple barriers of the intestinal epithelium. This work presents an oil‐structured nanoemulsion system that consists of a phase‐changeable fatty acid that allows EXT (EXT@PC/NEMs) to be delivered orally and absorbed efficiently in the small intestine. To construct an appropriate vehicle to encapsulate EXT, an oil‐in‐water single emulsion is generated at 37 °C, which is well above the melting point of the fatty acid but below the denaturation temperature of the peptide drug. The as‐prepared EXT@PC/NEMs are physically stable when stored at 4 °C, as they form a solid core, which prevents drug leakage. Upon their oral delivery at body temperature, the deformable liquid EXT@PC/NEMs may undergo effective cellular uptake, enhancing their permeability across the intestinal epithelium. The orally administered PC/NEMs significantly improve the bioavailability of EXT via intestinal lymphatic transport, ultimately accumulating in the pancreas, suggesting the possibility of orally delivering labile peptide drugs. The delivered EXT may act on pancreatic β‐ and α‐cells to stimulate insulin release and suppress glucagon secretion, respectively, reducing the blood glucose level, eventually having antidiabetic effects.