A novel method to obtain chitosan/DNA nanospheres and a study of their release properties

Development of a Nanoparticle Multiepitope DNA Vaccine against Virulent Infectious Bronchitis Virus Challenge

To develop a safe and effective nanoparticle (NP) multiepitope DNA vaccine for controlling infectious bronchitis virus (IBV) infection, we inserted the multiepitope gene expression box SBNT into a eukaryotic expression vector pcDNA3.1(+) to construct a recombinant plasmid pcDNA/SBNT. The NP multiepitope DNA vaccine pcDNA/SBNT-NPs were prepared using chitosan to encapsulate the recombinant plasmid pcDNA/SBNT, with a high encapsulation efficiency of 94.90 ± 1.35%. These spherical pcDNA/SBNT-NPs were 140.9 ± 73.2 nm in diameter, with a mean ζ potential of +16.8 ± 4.3 mV. Our results showed that the chitosan NPs not only protected the plasmid DNA from DNase degradation but also mediated gene transfection in a slow-release manner. Immunization with pcDNA/SBNT-NPs induced a significant IBV-specific immune response and partially protected chickens against homologous IBV challenge. Therefore, the chitosan NPs could be a useful gene delivery system, and NP multiepitope DNA vaccines may be a potential alternative for use in the development of a novel, safe, and effective IBV vaccine.

Reviewing Chitin/Chitosan Nanofibers and Associated Nanocomposites and Their Attained Medical Milestones

Chitin/chitosan research is an expanding field with wide scope within polymer research. This topic is highly inviting as chitin/chitosan's are natural biopolymers that can be recovered from food waste and hold high potentials for medical applications. This review gives a brief overview of the chitin/chitosan based nanomaterials, their preparation methods and their biomedical applications. Chitin nanofibers and Chitosan nanofibers have been reviewed, their fabrication methods presented and their biomedical applications summarized. The chitin/chitosan based nanocomposites have also been discussed. Chitin and chitosan nanofibers and their binary and ternary composites are represented by scattered superficial reports. Delving deep into synergistic approaches, bringing up novel chitin/chitosan nanocomposites, could help diligently deliver medical expectations. This review highlights such lacunae and further lapses in chitin related inputs towards medical applications. The grey areas and future outlook for aligning chitin/chitosan nanofiber research are outlined as research directions for the future.

Enhancement of Immune Response and Anti-Infection of Mice by Porcine Antimicrobial Peptides and Interleukin-4/6 Fusion Gene Encapsulated in Chitosan Nanoparticles

In order to develop a novel and effective immunoregulator to enhance both the immune response and antimicrobial function, a recombinant eukaryotic expression plasmid-pVAX1 co-expressing fusion cathelicidin antimicrobial peptides (CAMPs) and fusion porcine interleukin-4/6 gene (IL-4/6) was constructed and encapsulated in chitosan nanoparticles (CS-VAP4/6), prepared by the ionotropic gelation method. Four-week-old female Kunming mice were divided into three groups and intramuscularly injected, respectively, with CS-VAP, CS-VAP4/6, and CS-pVAX1. On 28 days post-inoculation, the mice were challenged by intraperitoneal injection with Staphylococcus aureus (ATCC 25923) and Escherichia coli (ATCC 25922); IgG, IgG1 and IgG2a, CD4+, and CD8+ T cells increased significantly in the VAP- and VAP4/6- treated mice, detected by ELISA and flow cytometry, correspondingly (p < 0.05). As analyzed by qPCR, expression levels of Toll-like receptor (TLR) 1, TLR4, TLR6, TLR9, IL-1, IL-2, IL-4, IL-6, IL-7, IL-12, IL-15, IL-23, Tumor Necrosis Factor (TNF)-α, and Interferon-gamma (IFN-γ) genes were also significantly up-regulated in comparison with those of the control mice (p < 0.05). Their immunological markers were elevated significantly to different degrees in CS-VAP4/6-treated mice compared with CS-VAP in different days post-inoculation (p < 0.05). After challenge with E. coli and Staphylococcus aureus, most of the VAP- and VAP4/6- treated mice survived, and no symptoms of bacterial infection were observed. In contrast, 80% of control mice died of infection. Among the treated groups, VAP4/6 had a stronger resistance against challenge with E. coli infection. These results demonstrated that the fusion gene of antimicrobial peptide and interleukin-4/6 has the promising potential as a safe and effective immunomodulator for the control of bacterial infections.

In Vitro Evaluation of Chitosan-DNA Plasmid Complex Encoding Jembrana Disease Virus Env-TM Protein as a Vaccine Candidate

Introduction

The development of Jembrana disease vaccine is an important effort to prevent losses in the Bali cattle industry in Indonesia. This study aims to prepare a Jembrana DNA vaccine encoding the transmembrane portion of the envelope protein in pEGFP-C1 and test the success of its delivery in culture cells using a chitosan-DNA complex.

Material and Methods

Cloning of the DNA vaccine was successfully performed on E. coli DH5α and confirmed by colony PCR, restriction analysis and sequencing. The plasmids were prepared as a chitosan complex using the complex coacervation method and physicochemically characterised using a particle size analyser. A transfection assay was performed in HeLa cells with 4 h exposure, and mRNA expression was assessed at 24 h post transfection.

Results

With a 1:2 (wt./wt.) ratio of DNA and chitosan, the complexes have a mean diameter of 236 nm, zeta potential value of + 17.9 mV, and showed no high toxicity potential in the HeLa cells. This complex successfully delivered the DNA into cells, as shown by the presence of a specific RT-PCR product (336 bp). However, the real-time PCR analysis showed that the delivery with chitosan complex resulted in lower target mRNA expression when compared with a commercial transfecting agent.

Conclusion

pEGFP-env-tm JDV as a candidate vaccine can be delivered as the chitosan-DNA complex and be expressed at the transcription level in vitro. This initial study will be used for further improvement and evaluation in vivo.

Nanomaterials as a game changer in the management and treatment of diabetic foot ulcers

Nanoengineered biomaterials have tremendously improved the range of tools utilized for the control of as well as acceleration of healing of diabetic foot ulcers (DFU) over the last few decades.

Improved stability and efficacy of chitosan/pDNA complexes for gene delivery

Among polymeric polycations, chitosan has emerged as a powerful carrier for gene delivery. Only a few studies have focused on the stability of the chitosan/DNA complex under storage, although this is imperative for nanomedicinal applications. Here, we synthesized polyelectrolyte complexes at a charge ratio of 10 using 50 kDa chitosan and plasmid (p)DNA that encodes a GFP reporter. These preparations were stable up to 3 months at 4 °C and showed reproducible transfection efficiencies in vitro in HEK293 cells. In addition, we developed a methodology that increases the in vitro transfection efficiency of chitosan/pDNA complexes by 150% with respect to standard procedures. Notably, intracellular pDNA release and transfected cells peaked 5 days following transection of mitotically active cells. These new developments in formulation technology enhance the potential for polymeric nanoparticle-mediated gene therapy.

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.

Chitosan-DNA complexes: charge inversion and DNA condensation

The design of biocompatible polyelectrolyte complexes is a promising strategy for in vivo delivery of biologically active macromolecules. Particularly, the condensation of DNA by polycations received considerable attention for its potential in gene delivery applications, where the development of safe and effective non-viral vectors remains a central challenge. Among polymeric polycations, Chitosan has recently emerged as a very interesting material for these applications. In this study, we compare the observed aggregation behavior of Chitosan-DNA complexes with the predictions of existing models for the complexation of oppositely charged polyelectrolytes. By using different and complementary microscopy approaches (AFM, FESEM and TEM), light scattering and electrophoretic mobility techniques, we characterized the structures of the complexes formed at different charge ratios and Chitosan molecular weight. In good agreement with theoretical predictions, a reentrant condensation, accompanied by charge inversion, is clearly observed as the polycation/DNA charge ratio is increased. In fact, the aggregates reach their maximum size in correspondence of a value of the charge ratio where their measured net charge inverts its sign. This value does not correspond to the stoichiometric 1:1 charge ratio, but is inversely correlated with the polycation length. Distinctive "tadpole-like" aggregates are observed in excess polycation, while only globular aggregates are found in excess DNA. Close to the isoelectric point, elongated fiber-like structures appear. Within the framework of the models discussed, different apparently uncorrelated observations reported in the literature find a systematic interpretation. These results suggest that these models are useful tools to guide the design of new and more efficient polycation-based vectors for a more effective delivery of genetic material.

Fabrication and characterization of DNA-loaded zein nanospheres

Background

Particulates incorporating DNA are promising vehicles for gene delivery, with the ability to protect DNA and provide for controlled, localized, and sustained release and transfection. Zein, a hydrophobic protein from corn, is biocompatible and has properties that make it a promising candidate material for particulate delivery, including its ability to form nanospheres through coacervation and its insolubility under physiological conditions, making it capable of sustained release of encapsulated compounds. Due to the promise of this natural biomaterial for drug delivery, the objective of this study was to formulate zein nanospheres encapsulating DNA as the therapeutic compound, and to characterize size, charge, sustained release, cell cytotoxicity and cellular internalization of these particles.

Results

Zein nanospheres encapsulating DNA were fabricated using a coacervation technique, without the use of harsh solvents or temperatures, resulting in the preservation of DNA integrity and particles with diameters that ranged from 157.8 ± 3.9 nm to 396.8 ± 16.1 nm, depending on zein to DNA ratio. DNA encapsulation efficiencies were maximized to 65.3 ± 1.9% with a maximum loading of 6.1 ± 0.2 mg DNA/g zein. The spheres protected encapsulated DNA from DNase I degradation and exhibited sustained plasmid release for at least 7 days, with minimal burst during the initial phase of release. Zein/DNA nanospheres demonstrated robust biocompatibility, cellular association, and internalization.

Conclusions

This study represents the first report on the formation of zein particles encapsulating plasmid DNA, using simple fabrication techniques resulting in preservation of plasmid integrity and tunable sizes. DNA encapsulation efficiencies were maximized to acceptable levels at higher zein to DNA ratios, while loading was comparable to that of other hydrophilic compounds encapsulated in zein and that of DNA incorporated into PLGA nano- and microspheres. The hydrophobic nature of zein resulted in spheres capable of sustained release of plasmid DNA. Zein particles may be an excellent potential tool for the delivery of DNA with the ability to be fine-tuned for specific applications including oral gene delivery, intramuscular delivery, and in the fabrication of tissue engineering scaffolds.

Nanoscale particle therapies for wounds and ulcers

‘Small is beautiful’ – this should be the slogan of nanoscientists. Indeed, working with particles less than 100 nm in size, nanotechnology is on the verge of providing a host of new materials and approaches, revolutionizing applied medicine. The obvious potential of nanotechnology has attracted considerable investment from governments and industry hoping to drive its economic development. Several areas of medical care already benefit from the advantages that nanotechnology provides and its application in wound healing will be reviewed in this article.

Chitin and chitosan as multipurpose natural polymers for groundwater arsenic removal and AS2O3 delivery in tumor therapy

Chitin and chitosan are natural polysaccharide polymers. These polymers have been used in several agricultural, food protection and nutraceutical applications. Moreover, chitin and chitosan have been also used in biomedical and biotechnological applications as drug delivery systems or in pharmaceutical formulations. So far, there are only few studies dealing with arsenic (As) removal from groundwater using chitin or chitosan and no evidence of the use of these natural polymers for arsenic trioxide (As₂O₃) delivery in tumor therapy. Here we suggest that chitin and/or chitosan might have the right properties to be employed as efficient polymers for such applications. Besides, nanotechnology offers suitable tools for the fabrication of novel nanostructured materials of natural origin. Since different nanostructured materials have already been employed successfully in various multidisciplinary fields, we expect that the integration of nanotechnology and natural polymer chemistry will further lead to innovative applications for environment and medicine.

Osmosis based method drives the self-assembly of polymeric chains into micro- and nanostructures

Polymers derived from monomers with a variety of functionalities provide materials with a vast range of properties and applications. Worldwide research has recently developed a wide number of methods suitable for the preparation of polymeric materials of nanometric dimensions, in view of the fact that, at the nanoscale level, new and unexpected properties emerge and lead to innovative applications. In this framework, we have exploited an easy method for the generation of nanostructures, regardless of the chemical structure of the pristine amorphous polymers, that is, biopolymers (e.g., polysaccharides) and synthetic, functional, and structural polymers (i.e, polystyrene, polymethylmethacrylates, polyacetylenes, and polymetallaynes). The nanostructure of these macromolecules, considered as the prototypes of various classes of polymeric materials, was achieved by using a simple and versatile procedure based on an osmotic method (OBM). Depending on the choice of solvent/nonsolvent pairs, the dialysis membrane molecular weight cutoff (MWCO), temperature, and polymer concentration, different morphologies can be obtained (e.g., spheres, sponges, disks, and fibers); also, a tuning of the nanoparticle dimensions ranging from the micro- to nanoscale has been obtained.

Bioengineered silk protein-based gene delivery systems

Silk proteins self-assemble into mechanically robust material structures that are also biodegradable and non-cytotoxic, suggesting utility for gene delivery. Since silk proteins can also be tailored in terms of chemistry, molecular weight and other design features via genetic engineering, further control of this system for gene delivery can be considered. In the present study, silk-based block copolymers were bioengineered with poly(L-lysine) domains for gene delivery. Ionic complexes of these silk-polylysine based block copolymers with plasmid DNA (pDNA) were prepared for gene delivery to human embryonic kidney (HEK) cells. The material systems were characterized by agarose gel electrophoresis, atomic force microscopy, and dynamic light scattering. The polymers self-assembled in solution and complexed plasmid DNA through ionic interactions. The pDNA complexes with 30 lysine residues prepared at a polymer/nucleotide ratio of 10 and with a solution diameter of 380 nm showed the highest efficiency for transfection. The pDNA complexes were also immobilized on silk films and demonstrated direct cell transfection from these surfaces. The results demonstrate the potential of bioengineered silk proteins as a new family of highly tailored gene delivery systems.