Effects of molecular weight and pyridinium moiety on water-soluble chitosan derivatives for mediated gene delivery

Cinchona Alkaloid Polymers Demonstrate Highly Efficient Gene Delivery Dependent on Stereochemistry, Methoxy Substitution, and Length

Nucleic acid delivery with cationic polymers is a promising alternative to expensive viral-based methods; however, it often suffers from a lower performance. Herein, we present a highly efficient delivery system based on cinchona alkaloid natural products copolymerized with 2-hydroxyethyl acrylate. Cinchona alkaloids are an attractive monomer class for gene delivery applications, given their ability to bind to DNA via both electrostatics and intercalation. To uncover the structure-activity profile of the system, four structurally similar cinchona alkaloids were incorporated into polymers: quinine, quinidine, cinchonine, and cinchonidine. These polymers differed in the chain length, the presence or absence of a pendant methoxy group, and stereochemistry, all of which were found to alter gene delivery performance and the ways in which the polymers overcome biological barriers to transfection. Longer polymers that contained the methoxy-bearing cinchona alkaloids (i.e., quinine and quinidine) were found to have the best performance. These polymers exhibited the tightest DNA binding, largest and most abundant DNA-polymer complexes, and best endosomal escape thanks to their increased buffering capacity and closest nuclear proximity of the payload. Overall, this work highlights the remarkable efficiency of polymer systems that incorporate cinchona alkaloid natural products while demonstrating the profound impact that small structural changes can have on overcoming biological hurdles associated with gene delivery.

Polymeric Delivery of Therapeutic Nucleic Acids

The advent of genome editing has transformed the therapeutic landscape for several debilitating diseases, and the clinical outlook for gene therapeutics has never been more promising. The therapeutic potential of nucleic acids has been limited by a reliance on engineered viral vectors for delivery. Chemically defined polymers can remediate technological, regulatory, and clinical challenges associated with viral modes of gene delivery. Because of their scalability, versatility, and exquisite tunability, polymers are ideal biomaterial platforms for delivering nucleic acid payloads efficiently while minimizing immune response and cellular toxicity. While polymeric gene delivery has progressed significantly in the past four decades, clinical translation of polymeric vehicles faces several formidable challenges. The aim of our Account is to illustrate diverse concepts in designing polymeric vectors towards meeting therapeutic goals of in vivo and ex vivo gene therapy. Here, we highlight several classes of polymers employed in gene delivery and summarize the recent work on understanding the contributions of chemical and architectural design parameters. We touch upon characterization methods used to visualize and understand events transpiring at the interfaces between polymer, nucleic acids, and the physiological environment. We conclude that interdisciplinary approaches and methodologies motivated by fundamental questions are key to designing high-performing polymeric vehicles for gene therapy.

Synthesis and Correlation of Aggregation and Antimicrobial Properties of Homochiral Quaternary Ammonium Bromides Derived from Camphoric Acid

A group of homochiral quaternary ammonium salts bearing hydrophobic camphoric acid-derived moiety was synthesized and characterized. The aggregation properties of the prepared compounds were evaluated by surface tension measurements, and the critical micelle concentration (CMC) was calculated. The novel quaternary ammonium bromides were tested as antimicrobial and antifungal agents, and their minimal inhibitory concentration (MIC) was evaluated and compared to clinically used benzalkonium bromide (BAB). Correlation of MIC with CMC reveals that monomers of prepared cationic surfactants, instead of micelles, are primarily responsible for antimicrobial activity.

A new prodrug and bioactivity evaluation of methotrexate based on Chitosan

Methotrexate (MTX) is the most important drug used in the treatment of several kinds of cancers, such as colon cancer. However, this drug can cause a reduction in the target tissue bioavailability. It is administered orally and absorbed quickly. This study aimed to produce an anti-colon cancer prodrug based on MTX via loading it into a biopolymer compound. Chitosan (CS) was extracted from scales of local fish by utilizing a previously published protocol. The MTX was then transformed to Methotrexate - imidazole and loaded into CS to prepare Chitosan - Methotrexate (CS-MTX) conjugates as colon cancer prodrugs. Fourier-transform infrared (FTIR), UV-visible spectroscopy, and 1H-NMR were used to analyse the structure of the prepared compounds. The prepared compounds were also tested for hemolytic activity. Chemical stability was studied using 0.2 M from the different buffer types with a pH of 1.2 and 7.4 over different periods about 240 min and kept in an incubator at 37 °C. The loading percentage was measured by hydrolysing the amide bond in basic media followed by the measurement of the absorbency at 273 nm. Three types of cancer cells, MCF-7, MDA-MB-231, and MDA-MB-453, were used to test the anticancer effects of CS-MTX by using tetrazolium bromide (MTT) assay. The results indicated that the viability of human breast cancer cell lines decreased because of the use of CS-MTX. This study also showed that CS-MTX was less toxic than the original drug. Therefore, it may be measured for additional biological analyses and medical applications. The results presented here showed that the new compound is remarkably stable in comparison with MTX and has longer half-life (t ½). Therefore, the CS-MTX has promising strategies through minimising the side effects of anti-colon tumour drugs.

Near-infrared/pH dual-responsive nanocomplexes for targeted imaging and chemo/gene/photothermal tri-therapies of non-small cell lung cancer

Combination therapy offers promising opportunities for treating advanced non-small cell lung cancer (NSCLC). Here, we established a chitosan-based nanocomplex CE7Q/CQ/S to deliver molecular-targeted drug erlotinib (Er), Survivin shRNA-expressing plasmid (SV), and photothermal agent heptamethine cyanine dye (Cy7) in one platform for simultaneous near-infrared (NIR) fluorescence imaging and triple-combination therapy of NSCLC bearing epidermal growth factor receptor (EGFR) mutations. The obtained CE7Q/CQ/S exhibited favorable photothermal effects, good DNA binding ability, and pH/NIR dual-responsive release behaviors. The conjugated Er could mediate specific delivery of Cy7 to EGFR-mutated NSCLC cells to enable targeted NIR fluorescence imaging and photothermal therapy (PTT). The in vitro and in vivo results showed that downregulation of Survivin expression and the photothermal effects could act synergistically with Er to induce satisfactory anticancer effects in either Er-sensitive or Er-resistant EGFR-mutated NSCLC cells. By integrating chemo/gene/photothermal therapies into one theranostic nanoplatform, CE7Q/CQ/S could significantly suppress EGFR-mutated NSCLC, indicating its potential use in treating NSCLC. STATEMENT OF SIGNIFICANCE: The development of epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKIs) has improved overall survival in patients with NSCLC driven by EGFR mutations. Unfortunately, the emergence of acquired resistance of EGFR-TKIs is almost inevitable after treatment. Here, we constructed a NIR/pH dual-responsive nanocomplex CE7Q/CQ/S based on chitosan which could integrate targeted near-infrared fluorescence imaging and chemo/gene/phototheramal tri-therapies together. We found that CE7Q/CQ/S possessed a promising outcome in fighting against EGFR-mutated NSCLC. The inhibition of Survivin expression and the application of photothermal therapy could act synergistically with erlotinib and reverse erlotinib resistance. The results of this work suggested that this chitosan-based combination therapeutic nanoplatform could be a promising candidate for NSCLC treatment.

Novel chitosan based nanoparticles as gene delivery systems to cancerous and noncancerous cells

The present study aimed to investigate in vitro DNA transfection efficiency of three novel chitosan derivatives: thiolated trimethyl chitosan (TMC-Cys), methylated 4-N,N dimethyl aminobenzyl N,O carboxymethyl chitosan(MABCC) and thiolated trimethyl aminobenzyl chitosan(MABC-Cys). After polymer synthesis and characterization, nanoparticles were prepared using these polymers and their size, zeta potential and DNA condensing ability were measured. After that, cytotoxicity and transfection efficiency of nanocomplexes were carried out in three different cells. The results showed that all polymers could condense DNA plasmid strongly from N/P 2 and nanocomplexes had eligible sizes and zeta potentials. Moreover, the nanocomplexes had negligible cytotoxicity and MABC-Cys was the most effective vehicle for gene delivery in HEK-293T cells. In the two other cell lines, SKOV-3 and MCF-7, TMC-Cys exhibited the highest transfection efficiency. This study indicated that chemical structure of these novel chitosan derivatives in the interaction with the cell type can lead to successful gene delivery.

Effect of the linear aliphatic amine functionalization on in vitro transfection efficiency of chitosan nanoparticles

The aim of this study is to prepare the long linear aliphatic amine pendant group-functionalized chitosan based nanoparticulate gene carrier system with improved properties for the efficient transfection. The amine functionalized chitosan (MChi) was synthesized by using N-(2-hydroxyethyl)ethylenediamine (HE-EDA) and characterized for the first time. The nanoparticles of MChi (nMChi) were prepared by ionic gelation method, and their particle size, polydispersity (PDI), zeta potential (mV), gene binding capacity and cytotoxicity were determined. Green Fluorescent Protein circular plasmid DNA (pEGFN1) loaded nanoparticles (gnMChi) were used in the transfection studies. The results showed that nMChi with a particle size of 102.9 nm and zeta potential of 41.9 ± 5.63 mV was non-toxic, had high transfection efficiency in Human Embryonic Kidney 293 and Primary Ovine Fibroblast cell lines and would be used as an efficient gene carrier system.

Pharmaceutical Potential of a Novel Chitosan Derivative Schiff Base with Special Reference to Antibacterial, Anti-Biofilm, Antioxidant, Anti-Inflammatory, Hemocompatibility and Cytotoxic Activities

PURPOSE

Chitosan and its derivatives possess several unique properties relevant in the field of pharmaceutics and medicinal chemistry. This study aimed to evaluate the pharmaceutical performance of an innovative chitosan derivative, methyl acrylate chitosan bearing p-nitrobenzaldehyde (MA*CS*pNBA) Schiff base.

METHODS

The antibacterial activity of MA*CS*pNBA was tested against multi-drug resistant (MDR) Gram-negative and Gram-positive bacteria using agar-well diffusion method. Anti-biofilm formation was analyzed using a microtitre plate. Antioxidant assays were performed to assess the scavenging activity of MA*CS*pNBA using DPPH, hydrogen peroxide, superoxide together with its reducing power activity. Anti-inflammatory activity was evaluated by albumin denaturation, membrane stabilization, and proteinase inhibition methods. MA*CS*pNBA was tested for its hemolytic efficiency on human erythrocytes. Cytotoxicity of MA*CS*pNBA was evaluated by MTT assay.

RESULTS

MA*CS*pNBA showed a significant performance as an antibacterial candidate against MDR bacteria, anti-biofilm, antioxidant and anti-inflammatory biomaterial, evidencing hemocompatibility and no cytotoxicity. It exhibited a significant negative correlation with biofilm formation by the MDR-PA-09 strain. Biological activities were found to be significantly concentration-dependent.

CONCLUSIONS

the newly chitosan derivative MA*CS*pNBA showed to be promising for pharmaceutical applications, expanding the treatment ways toward skin burn infections since it allied excellent antibacterial, anti-biofilm, antioxidant, anti-inflammatory, hemocompatibility and absence of cytotoxic activities.

Biocompatible polymeric nanocomplexes as an intracellular stimuli-sensitive prodrug for type-2 diabetes combination therapy

Combination therapy is usually considered as a promising strategy owing to its advantages such as reduced doses, minimized side effects and improved therapeutic efficiency in a variety of diseases including diabetes. Here we synthesized a new highly intracellular stimuli-sensitive chitosan-graft-metformin (CS-MET) prodrug by imine reaction between oxidative chitosan and metformin for type 2 diabetes (T2D) therapy. Hypothetically, CS-MET functions dually as an anti-diabetes prodrug as well as a gene delivery vector without superfluous materials. CS-MET formed nanocomplexes with therapeutic gene through electrostatic interactions and entered cells by Organic Cation Transporter (OCT)-independent endocytosis. The incorporation of metformin into chitosan has been found to increase endosomal escape via the proton sponge effect. When vector carrying a short-hairpin RNA (shRNA) silencing sterol regulatory element-binding protein (SREBP), a major transcription factor involved in de novo lipogenisis, it reduced the SREBP mRNA and proteins efficiently. Furthermore, by intraperitoneal injection, CS-MET/shSREBP nanocomplexes effectively knocked down SREBP in livers of western-type diet (WD)-induced obese C57BL/6J mice, markedly reversed insulin resistance and alleviated the fatty liver phenotype without obvious toxic effects. Thus we were able to show that the intracellular stimuli-sensitive CS-MET prodrug renders a potential platform to increase the anti-diabetes activity with synergistic enhancement of gene therapy.

Ligand-functionalized degradable polyplexes formed by cationic poly(aspartic acid)-grafted chitosan-cyclodextrin conjugates

Polypeptide-based degradable polyplexes attracted considerable attention in drug delivery systems. Polysaccharides including cyclodextrin (CD), dextran, and chitosan (CS) were readily grafted with cationic poly(aspartic acid)s (PAsps). To further enhance the transfection performances of PAsp-based polyplexes, herein, different types of ligand (folic acid, FA)-functionalized degradable polyplexes were proposed based on the PAsp-grafted chitosan-cyclodextrin conjugate (CCPE), where multiple β-CDs were tied on a CS chain. The FA-functionalized CCPE (i.e., CCPE-FA) was obtained via a host-guest interaction between the CD units of CCPE and the adamantane (Ad) species of Ad-modified FA (Ad-FA). The resulting CCPE/pDNA, CCPE-FA/pDNA, and ternary CCPE-FA/CCPE/pDNA (prepared by layer-by-layer assembly) polyplexes were investigated in detail using different cell lines. The CCPE-based polyplexes displayed much higher transfection efficiencies than the CS-based polyplexes reported earlier by us. The ternary polyplexes of CCPE-FA/CCPE/pDNA produced excellent gene transfection abilities in the folate receptor (FR)-positive tumor cells. This work would provide a promising means to produce highly efficient polyplexes for future gene therapy applications.

Synthesis of hyperpolarizable biomaterials at molecular level based on pyridinium–chitosan complexes

Novel types of fluorescent and quaternized pyridinium–chitosan derivatives have been synthesized and their characteristics as potential NLO-phore biomaterials have been disclosed by DFT calculations.

Synthesis, surface and antimicrobial properties of some quaternary ammonium homochiral camphor sulfonamides

A group of homochiral quaternary ammonium sulfonamides bearing hydrophobic camphor derived moieties were synthesized and characterized. The described synthetic procedure is quick and efficient. The novel quaternary ammonium bromides were tested as antimicrobial and antifungal agents. They exhibited strong antimicrobial and also antifungal activity, especially N-{2-[((1S, 4R)-7,7-dimethyl-2-oxobicyclo[2.2.1]heptan-1-yl)methylsulfonamido] ethyl}-N,N-dimethyltetradecan-1-aminium bromide 1c. The surface properties of prepared compounds were evaluated by surface tension measurements and critical micelle concentration (CMC) with surface tension at CMC (γCMC) was calculated.

Current progress in gene delivery technology based on chemical methods and nano-carriers

Gene transfer methods are promising in the field of gene therapy. Current methods for gene transfer include three major groups: viral, physical and chemical methods. This review mainly summarizes development of several types of chemical methods for gene transfer in vitro and in vivo by means of nano-carriers like; calcium phosphates, lipids, and cationic polymers including chitosan, polyethylenimine, polyamidoamine dendrimers, and poly(lactide-co-glycolide). This review also briefly introduces applications of these chemical methods for gene delivery.

Effect of N-pyridinium positions of quaternized chitosan on transfection efficiency in gene delivery system

Methylated N-pyridylmethyl chitosan chlorides (M-PyMeChCs) with a similar total degree of quaternization (DQT) and molecular weight but different N-pyridinium positions were synthesized by reductive amination and methylation, respectively. The effect of N-pyridinium positions on transfection efficiency and cytotoxicity was investigated in human hepatoma (Huh7) cell lines. The results revealed that M-PyMeChCs are able to form a complete complex formation with DNA since there is an N/P ratio of 5. The particle sizes of M-PyMeChCs/DNA nanopolyplexes were approximately 300 nm and indicated a positive charge. The morphology of these nanopolyplexes was found to be in a spherical shape which was investigated by using the transmission electron microscopy (TEM). The M4-PyMeChC/DNA nanopolyplexes showed highest in vitro transfection efficiency in Huh7 cells at N/P ratio of 20 compared to M2-PyMeChC/DNA and M3-PyMeChC/DNA nanopolyplexes. In comparison to M3-PyMeChC/DNA nanopolyplexes, M2-PyMeChC/DNA and M4-PyMeChC/DNA nanopolyplexes showed lower cytotoxicity in Huh7 cells. Our result demonstrated that N-pyridinium positions of M-PyMeChCs are related to transfection efficiency and cytotoxicity.