Polypeptide Nanoparticles with pH-Sheddable PEGylation for Improved Drug Delivery

pH-responsive self-assembled nanoparticles for tumor-targeted drug delivery

Recent advances in the field of drug delivery have opened new avenues for the development of novel nanodrug delivery systems (NDDS) in cancer therapy. Self-assembled nanoparticles (SANPs) based on tumour microenvironment have great advantages in improving antitumor effect, and pH-responsive SANPs prepared by the combination of pH-responsive nanomaterials and self-assembly technology can effectively improve the efficacy and reduce the systemic toxicity of antitumor drugs. In this review, we describe the characteristics of self-assembly and its driving force, the mechanism of pH-responsive NDDS, and the nanomaterials for pH-responsive SANPs type. A series of pH-responsive SANPs for tumour-targeted drug delivery are discussed, with an emphasis on the relation between structural features and theranostic performance.

Trap & kill: a neutrophil-extracellular-trap mimic nanoparticle for anti-bacterial therapy

Fenton chemistry-mediated antimicrobials have demonstrated great promise in antibacterial therapy. However, the short life span and diffusion distance of hydroxyl radicals dampen the therapeutic efficiency of these antimicrobials. Herein, inspired by the neutrophil extracellular trap (NET), in which bacteria are trapped and agglutinated via electronic interactions and killed by reactive oxygen species, we fabricated a NET-mimic nanoparticle to suppress bacterial infection in a "trap & kill" manner. Specifically, this NET-mimic nanoparticle was synthesized via polymerization of ferrocene monomers followed by quaternization with a mannose derivative. Similar to the NET, the NET-mimic nanoparticles trap bacteria through electronic and sugar-lectin interactions between their mannose moieties and the lectins of bacteria, forming bacterial agglutinations. Therefore, they confine the spread of the bacteria and restrict the bacterial cells to the destruction range of hydroxyl radicals. Meanwhile, the ferrocene component of the nanoparticle catalyzes the production of highly toxic hydroxyl radicals at the H2O2 rich infection foci and effectively eradicates the agglutinated bacteria. In a mouse model of an antimicrobial-resistant bacteria-infected wound, the NET-mimic nanoparticles displayed potent antibacterial activity and accelerated wound healing.

Polypeptide-Based Systems: From Synthesis to Application in Drug Delivery

Synthetic polypeptides are biocompatible and biodegradable macromolecules whose composition and architecture can vary over a wide range. Their unique ability to form secondary structures, as well as different pathways of modification and biofunctionalization due to the diversity of amino acids, provide variation in the physicochemical and biological properties of polypeptide-containing materials. In this review article, we summarize the advances in the synthesis of polypeptides and their copolymers and the application of these systems for drug delivery in the form of (nano)particles or hydrogels. The issues, such as the diversity of polypeptide-containing (nano)particle types, the methods for their preparation and drug loading, as well as the influence of physicochemical characteristics on stability, degradability, cellular uptake, cytotoxicity, hemolysis, and immunogenicity of polypeptide-containing nanoparticles and their drug formulations, are comprehensively discussed. Finally, recent advances in the development of certain drug nanoformulations for peptides, proteins, gene delivery, cancer therapy, and antimicrobial and anti-inflammatory systems are summarized.

Current Advances in Stimuli-Responsive Hydrogels as Smart Drug Delivery Carriers

In recent years, significant advancements in the field of advanced materials and hydrogel engineering have enabled the design and fabrication of smart hydrogels and nanogels that exhibit sensitivity to specific signals or pathological conditions, leading to a wide range of applications in drug delivery and disease treatment. This comprehensive review aims to provide an in-depth analysis of the stimuli-responsive principles exhibited by smart hydrogels in response to various triggers, such as pH levels, temperature fluctuations, light exposure, redox conditions, or the presence of specific biomolecules. The functionality and performance characteristics of these hydrogels are highly influenced by both their constituent components and fabrication processes. Key design principles, their applications in disease treatments, challenges, and future prospects were also discussed. Overall, this review aims to contribute to the current understanding of gel-based drug delivery systems and stimulate further research in this rapidly evolving field.

Dual drug loaded polypeptide delivery systems for cancer therapy

The present study was aimed to prepare and examine in vitro novel dual-drug loaded delivery systems. Biodegradable nanoparticles based on poly(L-glutamic acid-co-D-phenylalanine) were used as nanocarriers for encapsulation of two drugs from the paclitaxel, irinotecan, and doxorubicin series. The developed delivery systems were characterised with hydrodynamic diameters less than 300 nm (PDI < 0.3). High encapsulation efficiencies (≥75%) were achieved for all single- and dual-drug formulations. The release studies showed faster release at acidic pH, with the release rate decreasing over time. The release patterns of the co-encapsulated forms of substances differed from those of the separately encapsulated drugs, suggesting differences in drug-polymer interactions. The joint action of encapsulated drugs was analysed using the colon cancer cells, both for the dual-drug delivery sytems and a mixture of single-drug formulations. The encapsulated forms of the drug combinations demonstrated comparable efficacy to the free forms, with the encapsulation enhancing solubility of the hydrophobic drug paclitaxel.

A novel manganese dioxide-based drug delivery strategy via in situ coating γ-polyglutamic acid/cisplatin for intelligent anticancer therapy

Cisplatin (CDDP) is one of the most frequently used chemotherapeutic drugs due to its broad-spectrum and potent antitumor activity. Unfortunately, inactivation due to glutathione (GSH) substances and insufficient cellular uptake of CDDP greatly hinder its clinical applications. Herein, manganese dioxide (MnO₂) was reported as an efficient glutathione (GSH) consumption material for promoting the accumulation and preventing premature leakage of CDDP in tumor cells. In this work, γ-polyglutamic acid/cisplatin (PGA/CDDP) conjugates and PGA/CDDP nanoparticles (NPs) were respectively constructed via the ligand exchange reaction and electrostatic interaction. Furthermore, PGA/CDDP NPs were in situ coated with MnO₂ (PGA/CDDP@MnO₂ NPs) through the redox reaction of the residual carboxyl group (-COOH) and potassium permanganate (KMnO₄). As a result, the PGA/CDDP@MnO₂ NPs achieved a satisfactory drug-loading efficiency (ca. 37.26%) and multi-responsive controlled drug release. Remarkably, the MnO₂ shells exhibited excellent performance for efficient glutathione (GSH) consumption and significantly enhanced the killing effect (ca. 2-3 times) in human lung cancer cells (A549) compared with pure CDDP. Moreover, it was observed that PGA/CDDP@MnO₂ NPs could also inhibit the migration and invasion of A549 cells. Overall, these remarkable performances of PGA/CDDP@MnO₂ NPs make MnO₂ promising for controlled drug release and intelligent anticancer therapy.

Syntheses of Polypeptides and Their Biomedical Application for Anti-Tumor Drug Delivery

Polypeptides have attracted considerable attention in recent decades due to their inherent biodegradability and biocompatibility. This mini-review focuses on various ways to synthesize polypeptides, as well as on their biomedical applications as anti-tumor drug carriers over the past five years. Various approaches to preparing polypeptides are summarized, including solid phase peptide synthesis, recombinant DNA techniques, and the polymerization of activated amino acid monomers. More details on the polymerization of specifically activated amino acid monomers, such as amino acid N-carboxyanhydrides (NCAs), amino acid N-thiocarboxyanhydrides (NTAs), and N-phenoxycarbonyl amino acids (NPCs), are introduced. Some stimuli-responsive polypeptide-based drug delivery systems that can undergo different transitions, including stability, surface, and size transition, to realize a better anti-tumor effect, are elaborated upon. Finally, the challenges and opportunities in this field are briefly discussed.

Recent Advances in Poly(α-L-glutamic acid)-Based Nanomaterials for Drug Delivery

Poly(α-L-glutamic acid) (PGA) is a class of synthetic polypeptides composed of the monomeric unit α-L-glutamic acid. Owing to their biocompatibility, biodegradability, and non-immunogenicity, PGA-based nanomaterials have been elaborately designed for drug delivery systems. Relevant studies including the latest research results on PGA-based nanomaterials for drug delivery have been discussed in this work. The following related topics are summarized as: (1) a brief description of the synthetic strategies of PGAs; (2) an elaborated presentation of the evolving applications of PGA in the areas of drug delivery, including the rational design, precise fabrication, and biological evaluation; (3) a profound discussion on the further development of PGA-based nanomaterials in drug delivery. In summary, the unique structures and superior properties enables PGA-based nanomaterials to represent as an enormous potential in biomaterials-related drug delivery areas.

Fluorescent ABC-Triblock Polymer Nanocarrier for Cisplatin Delivery to Cancer Cells

Monitoring intracellular administration of non-luminescent anticancer drugs like cisplatin is a very challenging task in cancer research. Perylenebisimide (PBI) chromophore tagged fluorescent ABC-triblock polycaprolactone (PCL) nanoscaffold was engineered having carboxylic acid blocks for the chemical conjugation of cisplatin at the core and hydrophilic PEG blocks at the periphery. The amphiphilic ABC triblock Pt-prodrug was self-assembled into < 200 nm nanoparticles and exhibited excellent shielding against drug detoxification by the glutathione (GSH) species in the cytosol. In vitro drug release studies confirmed that the Pt-prodrug was stable at extracellular conditions and the PCL block exclusively underwent lysosomal-enzymatic biodegradation at the intracellular level to release the cisplatin drug in the active-form for accomplishing more than 90% cell growth inhibition. Confocal microscopic imaging of the red-fluorescence signals from the perylene chromophores established the simultaneous monitoring and delivery aspects of Pt-prodrug, and the proof-of-concept was successfully demonstrated in breast and cervical cancer cell lines.

Delivery nanoplatforms based on dynamic covalent chemistry

As a paramount factor to restrict the potential action of drugs and biologics, nanoplatforms based on dynamic covalent chemistry have been demonstrated as promising candidates to fulfill the full requirements during the whole delivery process by the virtue of their remarkable features such as adaptiveness, stimuli-responsiveness, specificity, reversibility and feasibility. This contribution summarizes the latest progress in dynamic covalent bond-based nanoplatforms with improved delivery efficiency and therapeutic performance. In addition, major challenges and perspectives in this field are also discussed. We expect that this feature article will provide a valuable and systematic reference for the further development of dynamic covalent bond-based nanoplatforms.

Strategies for the Development of pH-Responsive Synthetic Polypeptides and Polymer-Peptide Hybrids: Recent Advancements

Synthetic polypeptides and polymer-peptide hybrid materials have been successfully implemented in an array of biomedical applications owing to their biocompatibility, biodegradability and ability to mimic natural proteins. In addition, these materials have the capacity to form complex supramolecular structures, facilitate specific biological interactions, and incorporate a diverse selection of functional groups that can be used as the basis for further synthetic modification. Like conventional synthetic polymers, polypeptide-based materials can be designed to respond to external stimuli (e.g., light and temperature) or changes in the environmental conditions (e.g., redox reactions and pH). In particular, pH-responsive polypeptide-based systems represent an interesting avenue for the preparation of novel drug delivery systems that can exploit physiological or pathological pH variations within the body, such as those that arise in the extracellular tumour microenvironment, intracellularly within endosomes/lysosomes, or during tissue inflammation. Here, we review the significant progress made in advancing pH-responsive polypeptides and polymer-peptide hybrid materials during the last five years, with a particular emphasis on the manipulation of ionisable functional groups, pH-labile linkages, pH-sensitive changes to secondary structure, and supramolecular interactions.

Modified biomimetic core–shell nanostructures enable long circulation and targeted delivery for cancer therapy

A “Trojan horse” strategy realizes long circulation and precise targeting of Bio-RBCm@MSN–DOX nanoparticles to efficiently kill tumor cells.