Progress in chitosan-based vaccine delivery systems

Chitosan-functionalized graphene oxide as adjuvant in HEV P239 vaccine

Searching appropriate adjuvants for vaccine is a potent method to intense the immune efficacy. In the present study, we developed a novel Hepatitis E virus (HEV) vaccine by utilizing chitosan modified nano-graphene oxide (GO-CS) as an adjuvant to support HEV antigen P239 protein (GO/CS/P239). The characterization of GO/CS/P239 was observed by atomic force microscope. The safety of GO/CS/P239 was measured by CCK-8 method, hemolysis test and acute challenge test. The anti-HEV titers and cytokines production were analyzed by double antibody sandwich ELISA. As the results showed, by contrast with a vaccine that contained only the P239 protein, GO/CS/P239 vaccine can promote immune cells to produce more IgG antibodies and cytokines, which were able to stimulate the organism to produce stronger both cellular and humoral immunity. Collectively, GO/CS/P239 particles have been demonstrated to be safe both in vitro and in vivo, and can facilitate sufficient immune response to protect organisms from virus infection, which suggested that our exploration offers a promising alternative vaccine that can control HEV infection.

How the Lack of Chitosan Characterization Precludes Implementation of the Safe-by-Design Concept

Efficacy and safety of nanomedicines based on polymeric (bio)materials will benefit from a rational implementation of a Safe-by-Design (SbD) approach throughout their development. In order to achieve this goal, however, a standardization of preparation and characterization methods and their accurate reporting is needed. Focusing on the example of chitosan, a biopolymer derived from chitin and frequently used in drug and vaccine delivery vector preparation, this review discusses the challenges still to be met and overcome prior to a successful implementation of the SbD approach to the preparation of chitosan-based protein drug delivery systems.

Antimicrobial activity of endodontic sealers and medications containing chitosan and silver nanoparticles against Enterococcus faecalis

BACKGROUND

The main microorganism associated with the failure of endodontic treatments is Enterococcus faecalis. Although several endodontic therapeutics have demonstrated antimicrobial activity against E. faecalis, the antimicrobial effectiveness of chitosan (CsNPs) and silver nanoparticles (AgNPs) included into conventional endodontic sealers for endodontic therapies is still unclear.

AIM

The objective of this study was to evaluate the antibacterial activity increment (AAI) of endodontic sealers containing CsNPs and AgNPs as well as some chemical components against E. faecalis by direct contact assays.

METHODS

CsNPs and AgNPs were synthesized by reduction and ionic gelation methods, respectively. Nanoparticles were characterized by dynamic light scattering and energy dispersive X-ray analysis. The bactericidal activity was tested on monolayers on agar plates and collagen membrane surface assays against E. faecalis.

RESULTS

The size of CsNPs was 70.6±14.8 nm and zeta potential was 52.0±5.4 mV; the size of AgNPs was 54.2±8.5 nm, and zeta potential was -48.4±6.9 mV. All materials, single or combined, showed an AAI, especially when CsNPs, chlorhexidine (Chx), and the combination of CsNPs-Chx were added. However, the combination of CsNPs-Chx showed the highest (55%) AAI, followed by Chx (35.5%) and CsNPs (11.1%), respectively. There was a significant statistical difference in all comparisons (p < 0.05). Tubliseal (40%) and AH Plus (32%) sealants showed a higher AAI on E. faecalis in the monolayer test and collagen membrane assay analyzed by scanning electron microscopy.

CONCLUSIONS

Tubliseal and AH plus sealers combined with nanoparticles, especially CsNPs-Chx, could be used for conventional endodontic treatments in the control of E. faecalis bacteria.

Use of Biopolymers in Mucosally-Administered Vaccinations for Respiratory Disease

Communicable respiratory infections are the cause of a significant number of infectious diseases. The introduction of vaccinations has greatly improved this situation. Moreover, adjuvants have allowed for vaccines to be more effective with fewer adverse side effects. However, there is still space for improvement because while the more common injected formulations induce a systematic immunity, they do not confer the mucosal immunity needed for more thorough prevention of the spread of respiratory disease. Intranasal formulations provide systemic and mucosal immune protection, but they have the potential for more serious side effects and a less robust immune response. This review looks at seven different adjuvants—chitosan, starch, alginate, gellan, β-glucan, emulsan and hyaluronic acid—and their prospective ability to improve intranasal vaccines as adjuvants and antigen delivery systems.

Ligand decorated chitosan as an advanced nanocarrier for targeted delivery: a critical review

Nontargeted delivery systems present nonspecific delivery, low transfection efficiency and high toxicity. Ligand-conjugated chitosan (CS) nanocarriers have emerged as an outstanding option for achieving active delivery specifically and preferentially to the target sites by exploiting receptors mediated endocytosis. Mannosylated CS nanocarriers have brought tremendous breakthrough in gene therapy and have proven to be an excellent choice for treatment of infectious and inflammatory diseases. Similarly, folate and antibodies-conjugated CS play a significant role in diagnosis and treatment of various cancers. Current evidences obviously propose ligand-decorated CS as an attractive option for diagnosis and treatment of dreadful conditions. In order to bring huge revolution in the field of targeted delivery, challenges associated with these nanocarriers needs to be addressed.

Antimicrobial Properties of Biofunctionalized Silver Nanoparticles on Clinical Isolates of Streptococcus mutans and Its Serotypes

(1) Background: Streptococcus mutans (S. mutans) is the principal pathogen involved in the formation of dental caries. Other systemic diseases have also been associated with specific S. mutans serotypes (c, e, f, and k). Silver nanoparticles (SNP) have been demonstrated to have good antibacterial effects against S. mutans; therefore, limited studies have evaluated the antimicrobial activity of biofunctionalized SNP on S. mutans serotypes. The purpose of this work was to prepare and characterize coated SNP using two different organic components and to evaluate the antimicrobial activity of SNP in clinical isolates of S. mutans strains and serotypes; (2) Methods: SNP with bovine serum albumin (BSA) or chitosan (CS) coatings were prepared and the physical, chemical and microbiological properties of SNP were evaluated; (3) Results: Both types of coated SNP showed antimicrobial activity against S. mutans bacteria and serotypes. Better inhibition was associated with smaller particles and BSA coatings; however, no significant differences were found between the different serotypes, indicating a similar sensitivity to the coated SNP; (4) Conclusion: This study concludes that BSA and CS coated SNP had good antimicrobial activity against S. mutans strains and the four serotypes, and this study suggest the widespread use of SNP as an antimicrobial agent for the inhibition of S. mutans bacteria.

Intranasal immunisation of mice against Streptococcus equi using positively charged nanoparticulate carrier systems

In order to potentiate a strong immune response after mucosal vaccination with a low immunogenic S. equi enzymatic extract, two positively charged particulate delivery systems (liposomes and nanoparticles) were created. Positively surface charged particles were expected to efficiently bind to negatively charged cell membranes and facilitate antigen uptake. Phosphatidylcholine-cholesterol-stearylamine liposomes encapsulating S. equi antigens were prepared and dimensionated to 0.22±0.01μm with a polydispersity index <0.242, zeta potential of +12±4mV and an encapsulation efficiency of 13±3% (w/w). Chitosan nanoparticles were prepared by ionotropic gelation with sodium tripolyphosphate, presenting a particle size of 0.17±0.01μm with polydispersity index <0.362, zeta potential of +23±8mV and an encapsulation efficiency of 53±6% (w/w). Both encapsulation methods were recognised as innocuous once antigens structure remained intact after incorporation as assessed by SDS-PAGE. Intranasal immunisation of mice with both formulations successfully elicited mucosal, humoral and cellular immune responses. Mucosal stimulation was confirmed by increased sIgA levels in the lungs, being the chitosan nanoparticles more successful in this achievement probably due to their different mucoadhesive properties. Both formulations share the ability to induce Th1-mediated immune responses characterised by IFN-γ production and high IgG2a antibody titers as well as a Th2 immune response characterised mainly by IL-4 production and IgG1 antibodies.

Novel thermal-sensitive hydrogel enhances both humoral and cell-mediated immune responses by intranasal vaccine delivery

A novel thermal sensitive hydrogel was formulated with N-[(2-hydroxy-3-trimethylammonium) propyl] chitosan chloride (HTCC) and α, β-glycerophosphate (α, β-GP). A serial of hydrogels containing different amount of GP and HTCC with diverse quarternize degree (QD, 41%, 59%, 79.5%, and 99%) were prepared and characterized by rheological method. The hydrogel was subsequently evaluated for intranasal vaccine delivery with adenovirus based Zaire Ebola virus glycoprotein antigen (Ad-GPZ). Results showed that moderate quarternized HTCC (60% and 79.5%) hydrogel/antigen formulations induced highest IgG, IgG1, and IgG2a antibody titers in serum, as well as mucosal IgA responses in lung wash, which may attributed to the prolonged antigen residence time due to the thermal-sensitivity of this hydrogel. Furthermore, CD8(+) splenocytes for IFN-γ positive cell assay and the release profile of Th1/Th2 type cytokines (IFN-γ, IL-2, IL-10, and IL-4) showed that hydrogel/Ad-GPZ generated an overwhelmingly enhanced Th1 biased cellular immune response. In addition, this hydrogel displayed low toxicity to nasal tissue and epithelial cells even by frequently intranasal dosing of hydrogel. All these results strongly supported this hydrogel as a safe and effective delivery system for nasal immunization.

Bioderived polyelectrolyte nanogels for robust antigen loading and vaccine adjuvant effects

An easy but robust strategy for the synthesis of bioderived polyelectrolyte nanogels for protein antigen loading and vaccine adjuvant systems that can improve both humoral (Th2) and cellular immunity (Th1) is presented. The synthesized polyelectrolyte nanogels promote the uptake of antigens into antigen-presenting cells and strongly induce ovalbumin-specific INF-γ producing cells, cytotoxic T cell activity, and antibody production.

Chitosan and silver nanoparticles as pudding with raisins with antimicrobial properties

Chitosan nanoparticles (CS-NP) containing small silver nanoparticles are reported (Ag@CS-NP). CS-NP was synthesized using tripolyphosphate (TPP) as a polyanionic template. TPP also served to electrostatically attract Ag(+) inside CS-NP, where it was reduced by the terminal glucosamine units of the biopolymer. This procedure is environmental friendly, inexpensive, and permits the synthesis of very small AgNP (0.93-1.7 nm), with only a discrete dependence from the amount of silver nitrate used (5-200mg). The obtained hybrid nanocomposites Ag@CS-NP were characterized by DLS, HRTEM, and HAADF-STEM presenting a mean hydrodynamic diameter of 78 nm. The antimicrobial activity of Ag@CS-NP against Candida glabrata, Sacharomyces cerevisiae, Escherichia coli, Klebsiella pneumoniae, Salmonella, Staphylococcus aureus, and Bacillus cereus corresponded to MIC values lower than for AgNO(3).

Chitosan based polyelectrolyte complexes as potential carrier materials in drug delivery systems

Chitosan has been the subject of interest for its use as a polymeric drug carrier material in dosage form design due to its appealing properties such as biocompatibility, biodegradability, low toxicity and relatively low production cost from abundant natural sources. However, one drawback of using this natural polysaccharide in modified release dosage forms for oral administration is its fast dissolution rate in the stomach. Since chitosan is positively charged at low pH values (below its pK(a) value), it spontaneously associates with negatively charged polyions in solution to form polyelectrolyte complexes. These chitosan based polyelectrolyte complexes exhibit favourable physicochemical properties with preservation of chitosan's biocompatible characteristics. These complexes are therefore good candidate excipient materials for the design of different types of dosage forms. It is the aim of this review to describe complexation of chitosan with selected natural and synthetic polyanions and to indicate some of the factors that influence the formation and stability of these polyelectrolyte complexes. Furthermore, recent investigations into the use of these complexes as excipients in drug delivery systems such as nano- and microparticles, beads, fibers, sponges and matrix type tablets are briefly described.