A novel peptide dendrimer LTP efficiently facilitates transfection of mammalian cells

Synthesis and Biological Properties of Polyphenol-Containing Linear and Dendrimeric Cationic Peptides

Natural polyphenols are promising compounds for the pharmacological control of oxidative stress in various diseases. However, low bioavailability and rapid metabolism of polyphenols in a form of glycosides or aglycones have stimulated the search for the vehicles that would provide their efficient delivery to the systemic circulation. Conjugation of polyphenols with cationic amphiphilic peptides yields compounds with a strong antioxidant activity and ability to pass through biological barriers. Due to a broad range of biological activities characteristic of polyphenols and peptides, their conjugates can be used in the antioxidant therapy, including the treatment of viral, oncological, and neurodegenerative diseases. In this work, we synthesized linear and dendrimeric cationic amphiphilic peptides that were then conjugated with gallic acid (GA). GA is a non-toxic natural phenolic acid and an important functional element of many flavonoids with a high antioxidant activity. The obtained GA-peptide conjugates showed the antioxidant (antiradical) activity that exceeded 2-3 times the antioxidant activity of ascorbic acid. GA attachment had no effect on the toxicity and hemolytic activity of the peptides. GA-modified peptides stimulated the transmembrane transfer of the pGL3 plasmid encoding luciferase reporter gene, although GA attachment at the N-terminus of peptides reduced their transfection activity. Several synthesized conjugates demonstrated the antibacterial activity in the model of Escherichia coli Dh5α growth inhibition.

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.

Peptides as carriers of active ingredients: A review

Bioactive compounds are highly valuable in the fields of food and medicine, but their application is limited due to easy deterioration after oral or skin administration. In recent years, the use of peptides as delivery systems for bioactive compounds has been intensively researched because of their special physicochemical characteristics. Peptides can be assembled using various preparation methods and can form several composite materials such as hydrogels, micelles, emulsions and particles. The composite material properties are determined by peptides, bioactive compounds and the construction methods employed. Herein, this paper provides a comprehensive review of the peptides used for active ingredients delivery, fabrication methods for creating delivery systems, structures, targeting characteristics, functional activities and mechanism of delivery systems, as well as their absorption and metabolism, which provided theoretical basis and reference for further research and development of functional composites.

Overcoming the challenge: cell-penetrating peptides and membrane permeability

<p>Cell-penetrating peptides (CPPs) have emerged as a promising strategy for enhancing the membrane permeability of bioactive molecules, particularly in the treatment of central nervous system diseases. CPPs possess the ability to deliver a diverse array of bioactive molecules into cells using either covalent or non-covalent approaches, with a preference for non-covalent methods to preserve the biological activity of the transported molecules. By effectively traversing various physiological barriers, CPPs have exhibited significant potential in preclinical and clinical drug development. The discovery of CPPs represents a valuable solution to the challenge of limited membrane permeability of bioactive molecules and will continue to exert a crucial influence on the field of biomedical science.</p>

Electrochemical DNA-Sensor Based on Macrocyclic Dendrimers with Terminal Amino Groups and Carbon Nanomaterials

The assembling of thiacalix[4]arene-based dendrimers in cone, partial cone, and 1,3-alternate configuration on the surface of a glassy carbon electrode coated with carbon black or multiwalled carbon nanotubes has been characterized using cyclic voltammetry, electrochemical impedance spectroscopy, and scanning electron microscopy. Native and damaged DNA were electrostatically accumulated on the modifier layer. The influence of the charge of the redox indicator and of the macrocycle/DNA ratio was quantified and the roles of the electrostatic interactions and of the diffusional transfer of the redox indicator to the electrode interface indicator access were established. The developed DNA sensors were tested on discrimination of native, thermally denatured, and chemically damaged DNA and on the determination of doxorubicin as the model intercalator. The limit of detection of doxorubicin established for the biosensor based on multi-walled carbon nanotubes was equal to 1.0 pM with recovery from spiked human serum of 105-120%. After further optimization of the assembling directed towards the stabilization of the signal, the developed DNA sensors can find application in the preliminary screening of antitumor drugs and thermal damage of DNA. They can also be applied for testing potential drug/DNA nanocontainers as future delivery systems.

Redesigning of Cell-Penetrating Peptides to Improve Their Efficacy as a Drug Delivery System

Cell-penetrating peptides (CPP) are promising tools for the transport of a broad range of compounds into cells. Since the discovery of the first members of this peptide family, many other peptides have been identified; nowadays, dozens of these peptides are known. These peptides sometimes have very different chemical–physical properties, but they have similar drawbacks; e.g., non-specific internalization, fast elimination from the body, intracellular/vesicular entrapment. Although our knowledge regarding the mechanism and structure–activity relationship of internalization is growing, the prediction and design of the cell-penetrating properties are challenging. In this review, we focus on the different modifications of well-known CPPs to avoid their drawbacks, as well as how these modifications may increase their internalization and/or change the mechanism of penetration.

TAT for Enzyme/Protein Delivery to Restore or Destroy Cell Activity in Human Diseases

Much effort has been dedicated in the recent decades to find novel protein/enzyme-based therapies for human diseases, the major challenge of such therapies being the intracellular delivery and reaching sub-cellular organelles. One promising approach is the use of cell-penetrating peptides (CPPs) for delivering enzymes/proteins into cells. In this review, we describe the potential therapeutic usages of CPPs (mainly trans-activator of transcription protein, TAT) in enabling the uptake of biologically active proteins/enzymes needed in cases of protein/enzyme deficiency, concentrating on mitochondrial diseases and on the import of enzymes or peptides in order to destroy pathogenic cells, focusing on cancer cells.

Silencing of SARS-CoV-2 with modified siRNA-peptide dendrimer formulation

Background

First vaccines for prevention of Coronavirus disease 2019 (COVID‐19) are becoming available but there is a huge and unmet need for specific forms of treatment. In this study we aimed to evaluate the anti‐SARS‐CoV‐2 effect of siRNA both in vitro and in vivo.

Methods

To identify the most effective molecule out of a panel of 15 in silico designed siRNAs, an in vitro screening system based on vectors expressing SARS‐CoV‐2 genes fused with the firefly luciferase reporter gene and SARS‐CoV‐2‐infected cells was used. The most potent siRNA, siR‐7, was modified by Locked nucleic acids (LNAs) to obtain siR‐7‐EM with increased stability and was formulated with the peptide dendrimer KK‐46 for enhancing cellular uptake to allow topical application by inhalation of the final formulation – siR‐7‐EM/KK‐46. Using the Syrian Hamster model for SARS‐CoV‐2 infection the antiviral capacity of siR‐7‐EM/KK‐46 complex was evaluated.

Results

We identified the siRNA, siR‐7, targeting SARS‐CoV‐2 RNA‐dependent RNA polymerase (RdRp) as the most efficient siRNA inhibiting viral replication in vitro. Moreover, we showed that LNA‐modification and complexation with the designed peptide dendrimer enhanced the antiviral capacity of siR‐7 in vitro. We demonstrated significant reduction of virus titer and lung inflammation in animals exposed to inhalation of siR‐7‐EM/KK‐46 in vivo.

Conclusions

Thus, we developed a therapeutic strategy for COVID‐19 based on inhalation of a modified siRNA‐peptide dendrimer formulation. The developed medication is intended for inhalation treatment of COVID‐19 patients.

Why the Orientational Mobility in Arginine and Lysine Spacers of Peptide Dendrimers Designed for Gene Delivery Is Different?

New peptide dendrimer with Lys-2Arg repeating units was recently studied experimentally by NMR (RSC Advances, 2019, 9, 18018) and tested as gene carrier successfully (Int. J. Mol. Sci., 2020, 21, 3138). The unusual slowing down of the orientational mobility of 2Arg spacers in this dendrimer was revealed. It has been suggested that this unexpected behavior is caused by the Arg-Arg pairing effect in water, which leads to entanglements between dendrimer branches. In this paper, we determine the reason for this slowing down using atomistic molecular dynamics simulation of this dendrimer. We present that the structural properties of Lys-2Arg dendrimer are close to those of the Lys-2Lys dendrimer at all temperatures (Polymers, 2020, 12, 1657). However, the orientational mobility of the H-H vector in CH2-N groups of 2Arg spacers in Lys-2Arg dendrimer is significantly slower than the mobility of the same vector in the Lys-2Lys dendrimer. This result is in agreement with the recent NMR experiments for the same systems. We revealed that this difference is not due to the arginine-arginine pairing, but is due to the semiflexibility effect associated with the different contour length from CH2-N group to the end of the side arginine or lysine segment in spacers.

Peptide-Based Nanoassemblies in Gene Therapy and Diagnosis: Paving the Way for Clinical Application

Nanotechnology approaches play an important role in developing novel and efficient carriers for biomedical applications. Peptides are particularly appealing to generate such nanocarriers because they can be rationally designed to serve as building blocks for self-assembling nanoscale structures with great potential as therapeutic or diagnostic delivery vehicles. In this review, we describe peptide-based nanoassemblies and highlight features that make them particularly attractive for the delivery of nucleic acids to host cells or improve the specificity and sensitivity of probes in diagnostic imaging. We outline the current state in the design of peptides and peptide-conjugates and the paradigms of their self-assembly into well-defined nanostructures, as well as the co-assembly of nucleic acids to form less structured nanoparticles. Various recent examples of engineered peptides and peptide-conjugates promoting self-assembly and providing the structures with wanted functionalities are presented. The advantages of peptides are not only their biocompatibility and biodegradability, but the possibility of sheer limitless combinations and modifications of amino acid residues to induce the assembly of modular, multiplexed delivery systems. Moreover, functions that nature encoded in peptides, such as their ability to target molecular recognition sites, can be emulated repeatedly in nanoassemblies. Finally, we present recent examples where self-assembled peptide-based assemblies with "smart" activity are used in vivo. Gene delivery and diagnostic imaging in mouse tumor models exemplify the great potential of peptide nanoassemblies for future clinical applications.

Linear and dendrimeric antiviral peptides: design, chemical synthesis and activity against human respiratory syncytial virus

Novel artificial peptides possess anti-RSV activity through a combination of two mechanisms: direct nonspecific destabilization of the viral envelope and competitive interaction with the RSV cellular receptor.

Designer Peptide and Protein Dendrimers: A Cross-Sectional Analysis

Dendrimers have attracted immense interest in science and technology due to their unique chemical structure that offers a myriad of opportunities for researchers. Dendritic design allows us to present peptides in a branched three-dimensional fashion that eventually leads to a globular shape, thus mimicking globular proteins. Peptide dendrimers, unlike other classes of dendrimers, have immense applications in biomedical research due to their biological origin. The diversity of potential building blocks and innumerable possibilities for design, along with the fact that the area is relatively underexplored, make peptide dendrimers sought-after candidates for various applications. This review summarizes the stepwise evolution of peptidic dendrimers along with their multifaceted applications in various fields. Further, the introduction of biomacromolecules such as proteins to a dendritic scaffold, resulting in complex macromolecules with discrete molecular weights, is an altogether new addition to the area of organic chemistry. The synthesis of highly complex and fully folded biomacromolecules on a dendritic scaffold requires expertise in synthetic organic chemistry and biology. Presently, there are only a handful of examples of protein dendrimers; we believe that these limited examples will fuel further research in this area.

Stereoselective pH Responsive Peptide Dendrimers for siRNA Transfection

Transfecting nucleic acids into cells is an essential procedure in biological research usually performed using nonviral transfection reagents. Unfortunately, most transfection reagents have polymeric or undisclosed structures and require nonstandard synthetic procedures. Herein we report peptide dendrimers accessible as pure products from standard building blocks by solid-phase peptide synthesis and acting as nontoxic single component siRNA transfection reagents for a variety of cell lines with equal or better performance than the gold standard lipofectamine L2000. Structure-activity relationships and mechanistic studies illuminate their transfection mechanism in unprecedented detail. Stereoselective dendrimer aggregation via intermolecular β-sheets at neutral pH enables siRNA complexation to form nanoparticles which enter cells by endocytosis. Endosome acidification triggers protonation of amino termini and rearrangement to an α-helical conformation forming smaller dendrimer/siRNA nanoparticles, which escape the endosome and release their siRNA cargo in the cytosol. Two particularly efficient d-enantiomeric dendrimers are proposed as new reference reagents for siRNA transfection.

Recent Advances in Cell Penetrating Peptide-Based Anticancer Therapies

Cell-penetrating-peptides (CPPs) are small amino-acid sequences characterized by their ability to cross cellular membranes. They can transport various bioactive cargos inside cells including nucleic acids, large proteins, and other chemical compounds. Since 1988, natural and synthetic CPPs have been developed for applications ranging from fundamental to applied biology (cell imaging, gene editing, therapeutics delivery). In recent years, a great number of studies reported the potential of CPPs as carriers for the treatment of various diseases. Apart from a good efficacy due to a rapid and potent delivery, a crucial advantage of CPP-based therapies is the peptides low toxicity compared to most drug carriers. On the other hand, they are quite unstable and lack specificity. Higher specificity can be obtained using a cell-specific CPP to transport the therapeutic agent or using a non-specific CPP to transport a cargo with a targeted activity. CPP-cargo complexes can also be conjugated to another moiety that brings cell- or tissue-specificity. Studies based on all these approaches are showing promising results. Here, we focus on recent advances in the potential usage of CPPs in the context of cancer therapy, with a particular interest in CPP-mediated delivery of anti-tumoral proteins.