Immunological Assessment of Chitosan or Trimethyl Chitosan-Coated PLGA Nanospheres Containing Fusion Antigen as the Novel Vaccine Candidates Against Tuberculosis

Biodegradable nanoplatforms for antigen delivery: part I - state of the art review of polymeric nanoparticles for cancer immunotherapy

INTRODUCTION

Polymeric nanoparticles used for antigen delivery against infections and for cancer immunotherapy are an emerging therapeutic strategy in promoting the development of innovative vaccines. Beyond their capability to create targeted delivery systems with controlled release of payloads, biodegradable polymers are utilized for their ability to enhance the immunogenicity and stability of antigens.

AREAS COVERED

This review extensively discusses the physicochemical parameters that affect the behavior of nanoparticles as antigen-delivery systems. Additionally, various types of natural and synthetic polymers and recent advancements in nanoparticle-based targeted vaccine production are reviewed.

EXPERT OPINION

Biodegradable polymeric nanoparticles have gained major interest in the vaccination filed and have been extensively used to encapsulate antigens against a wide variety of tumors. Moreover, their versatility in terms of tunning their physicochemical characteristics, and their surface, facilitates the targeting to antigen presenting cells and enhances immune response.

Chitosan non-particulate vaccine delivery systems

Chitosan is an extensively used polymer for drug delivery applications in particulate and non-particulate carriers. Chitosan-based particulate, nano-, and microparticle, carriers have been the most extensively studied for the delivery of therapeutics and vaccines. However, chitosan has also been used in vaccine applications for its adjuvant properties in various hydrogels or as a carrier coating material. The focus of this review will be on the usage of chitosan as a vaccine adjuvant based on its intrinsic immunogenicity; the various forms of chitosan-based non-particulate delivery systems such as thermosensitive hydrogels, microneedles, and conjugates; and the advantages of its role as a coating material for vaccine carriers.

Weibull β value for the discernment of drug release mechanism of PLGA particles

Mathematical models are used to characterize and optimize drug release in drug delivery systems (DDS). One of the most widely used DDS is the poly(lactic-co-glycolic acid) (PLGA)-based polymeric matrix owing to its biodegradability, biocompatibility, and easy manipulation of its properties through the manipulation of synthesis processes. Over the years, the Korsmeyer-Peppas model has been the most widely used model for characterizing the release profiles of PLGA DDS. However, owing to the limitations of the Korsmeyer-Peppas model, the Weibull model has emerged as an alternative for the characterization of the release profiles of PLGA polymeric matrices. The purpose of this study was to establish a correlation between the n and β parameters of the Korsmeyer-Peppas and Weibull models and to use the Weibull model to discern the drug release mechanism. A total of 451 datasets describing the overtime drug release of PLGA-based formulations from 173 scientific articles were fitted to both models. The Korsmeyer-Peppas model had a mean Akaike Information Criteria (AIC) value of 54.52 and an n value of 0.42, while the Weibull model had a mean AIC of 51.99 and a β value of 0.55, and by using reduced major axis regression values, a high correlation was found between the n and β values. These results demonstrate the ability of the Weibull model to characterize the release profiles of PLGA-based matrices and the usefulness of the β parameter for determining the drug release mechanism.

Natural Polymeric Composites Derived from Animals, Plants, and Microbes for Vaccine Delivery and Adjuvant Applications: A Review

A key element in ensuring successful immunization is the efficient delivery of vaccines. However, poor immunogenicity and adverse inflammatory immunogenic reactions make the establishment of an efficient vaccine delivery method a challenging task. The delivery of vaccines has been performed via a variety of delivery methods, including natural-polymer-based carriers that are relatively biocompatible and have low toxicity. The incorporation of adjuvants or antigens into biomaterial-based immunizations has demonstrated better immune response than formulations that just contain the antigen. This system may enable antigen-mediated immunogenicity and shelter and transport the cargo vaccine or antigen to the appropriate target organ. In this regard, this work reviews the recent applications of natural polymer composites from different sources, such as animals, plants, and microbes, in vaccine delivery systems.

Polylactide Perspectives in Biomedicine: From Novel Synthesis to the Application Performance

The incessant developments in the pharmaceutical and biomedical fields, particularly, customised solutions for specific diseases with targeted therapeutic treatments, require the design of multicomponent materials with multifunctional capabilities. Biodegradable polymers offer a variety of tailored physicochemical properties minimising health adverse side effects at a low price and weight, which are ideal to design matrices for hybrid materials. PLAs emerge as an ideal candidate to develop novel materials as are endowed withcombined ambivalent performance parameters. The state-of-the-art of use of PLA-based materials aimed at pharmaceutical and biomedical applications is reviewed, with an emphasis on the correlation between the synthesis and the processing conditions that define the nanostructure generated, with the final performance studies typically conducted with either therapeutic agents by in vitro and/or in vivo experiments or biomedical devices.

Synchronizing the release rates of topotecan and paclitaxel from a self-eroding crosslinked chitosan - PLGA platform

This study is a continuation of a previous study in which two model drugs, sodium salicylate (highly water-soluble) and indomethacin (low water-soluble) were loaded into an erodible hydrogel, made of ionically crosslinked chitosan (x-Ct). The erosion rate of the x-Ct matrix was controlled by its immersion in calcium chloride solutions (de-crosslinker) of different concentrations, leading to synchronization of the release rates of the two drugs over 2 h. In the present study, a modified platform was developed in order to (a) synchronize the release rates of the two cytotoxic drugs, topotecan (TT, highly water soluble) and paclitaxel (PTX, poorly water soluble); (b) prolong the erosion duration and the derived concomitant release of the two drugs to several days. TT was loaded into a PLGA sphere, which was co-loaded with calcium chloride (CaCl₂). The sphere was then placed in an aqueous solution of chitosan (Ct) in which PTX was dispersed. A PLGA core-containing hydrogel was then produced by ionically crosslinking the Ct. The formulation screening section of the study includes a statistically designed Fractional Factorial experiment. It was comprised of the following five experimental factors: (a) the type of Ct and (b) its relative amount in the formulation, (c) the type of ionic crosslinker (citric acid or oxalic acid), (d) the concentration of the ionic crosslinker and (e) the co-loaded amounts of CaCl₂ (the constitutional de-crosslinking agent). The difference factor, f1, and the similarity factor, f2, of the TT and PTX release profiles into water, were used as the experimental responses. The computerized prediction models were employed to assess the collective effects of the pre-determined experimental factors on the difference factor, f1, and the similarity factor, f2 (the response factors), by employing a fractional factorial design and multifactorial analysis, without the need to account for the exact mechanisms of the release processes involved. The final composite platform was capable of releasing TT and PTX, at similar (concomitant) rates, over a period of 7 days, a finding which suggests that the novel polymeric platform may serve as a multi-drug implant. An attractive medical application for such a device would be post-operative local treatment that could benefit from localized combination chemotherapy after the removal of malignant tissues, in the surgical treatment of breast cancer, ovarian cancer, glioma and peritoneal carcinomatosis.