Interests of chitosan nanoparticles ionically cross-linked with tripolyphosphate for biomedical applications

Developed simvastatin chitosan nanoparticles co-crosslinked with tripolyphosphate and chondroitin sulfate for ASGPR-mediated targeted HCC delivery with enhanced oral bioavailability

Simvastatin (SV) repurposing has emerged as an alternative approach for the treatment of cancer. In this study, SV chitosan nanoparticles co-crosslinked with tripolyphosphate and chondroitin sulfate (SVCSChSNPs) were developed in order to maximize SV therapeutic efficiency. The hepatic targeting was realized using N-acetylgalactosamine (GalNAc) residues of ChS, which can be identified by the ASGPR receptors specifically expressed in hepatocytes. SV was repurposed as an anticancer agent against hepatocellular carcinoma (HCC). NPs were fabricated by the ionic gelation method, and the formulation variables (CS concentration, CS:ChS ratio, and CS solution pH) were optimized using a three-factor, three-level Box-Behnken design. The optimized NPs were investigated for particle size, size distribution, zeta potential, morphology, in vitro cytotoxicity, apoptotic effects against human hepatocellular carcinoma HepG2 cells, and detection of intracellular localization. The NPs were further evaluated for in vitro release behavior of SV and pharmacokinetics using Wister albino rats. Transmission electron microscopy (TEM) imaging showed a spherical shape with regular surface NPs of < 100 nm diameter. In vitro cytotoxicity testing showed that the SVCSChSNPs exhibited greater inhibition of proliferation in HepG2 cells and high cellular uptake through ASGPR-mediated endocytosis. The in vitro dissolution profile was 2.1-fold greater than that of pure SV suspension. Furthermore, in vivo oral pharmacokinetics revealed that the obtained NPs enhanced the bioavailability of SV by up to 2- and 1.6-fold for SV and SVA, respectively, compared to the pure SV suspension. These findings demonstrated that hepatic-targeted CSChSNPs delivering SV could potentially serve as a promising platform for HCC and other liver-related diseases.

Chitosan nanobeads loaded with Biginelli hybrids as cell-selective toxicity systems with a homogeneous distribution of the cell cycle in cancer treatment

Tetrahydropyrimidines are a class of azaheterocycles, also called Biginelli hybrids (obtained from the Biginelli reaction), that have attracted an enormous interest in the medicinal chemistry community in recent years, due to a broad biological activity, such as anticancer, antiviral, anti-inflammatory, antidiabetic, antituberculosis activities, etc. According to SciFinder®, more than 70 000 different Biginelli-like compounds have been covered in publications. However, although the Biginelli reaction can yield a large number of compounds with a broad range of activities, none of them have been captured in a carrier. In this study, chitosan-based (Ch) nanoparticles (NPs) containing three different molecules (Biginelli hybrids) were developed and tested for the first time as simple and promising vehicles for anticancer Biginelli-based drugs. The key features of NPs, such as size, surface morphology, drug encapsulation efficiency, and in vitro release were systematically investigated. Rather weak cell selectivity of pure Biginelli hybrids (A–C) to selected cancer cell lines has improved and this has been accompanied with two-to-four times stronger cytotoxic effect of A–C loaded Ch NPs, with a triple reduction in toxicity to healthy cells (MRC-5). It has been observed that the examined NPs induce apoptosis. The cell cycle analysis has confirmed the influence of A-loaded Ch (A-Ch), B-loaded Ch (B-Ch), and C-loaded Ch (C-Ch) on the cell cycle distribution, which was homogenously affected. This is the difference with regard to the effect of A, B, and C on the cell cycle. It has been established that the increased selectivity and antitumor activity of NPs are related to the presence of the carrier.

Chitosan nanoparticles containing tetrahydropyrimidines were developed and tested for the first time as simple and promising vehicles for anticancer Biginelli-based drugs.

Polysaccharide nanoparticles for oral controlled drug delivery: the role of drug-polymer and interpolymer interactions

Introduction: The oral route still represents the most popular way of administering drugs; nowadays oral administration faces new challenges, in particular with regards to the delivery of APIs that are poorly absorbed and sensitive to degradation such as macromolecules and biotechnological drugs. Nanoparticles are promising tools for the efficient delivery of these drugs to the gastrointestinal tract. Areas covered:Approaches and techniques for the formulation of drugs, with particular focus on the preparation of polysaccharide nanoparticles obtained by non-covalent interactions. Expert opinion:Polysaccharide-based nanoparticulate systems offer the opportunity to address some of the issues posed by biotechnological drugs, as well as by small molecules, with problems of stability/intestinal absorption, by exploiting the capability of the polymer to establish non-covalent bonds with functional groups in the chemical structure of the API. This area of research will continue to grow, provided that these drug delivery technologies will efficaciously be translated into systems that can be manufactured on a large scale under GMP conditions. Industrial scale-up represents the biggest obstacle to overcome in view of the transformation of very promising results obtained on lab scale into medicinal products. To do that, an effort toward the simplification of the process and technologies is necessary.

Recent Progress of Chitosan and Chitosan Derivatives-Based Nanoparticles: Pharmaceutical Perspectives of Oral Insulin Delivery

Diabetes mellitus is a chronic endocrine disease, affecting more than 400 million people around the world. Patients with poorly controlled blood glucose levels are liable to suffer from life-threatening complications, such as cardiovascular, neuropathy, retinopathy and even premature death. Today, subcutaneous parenteral is still the most common route for insulin therapy. Oral insulin administration is favourable and convenient to the patients. In contrast to injection route, oral insulin delivery mimics the physiological pathway of endogenous insulin secretion. However, oral insulin has poor bioavailability (less than 2%) due to the harsh physiological environment through the gastrointestinal tract (GIT). Over the last few decades, many attempts have been made to achieve an effective oral insulin formulation with high bioavailability using insulin encapsulation into nanoparticles as advanced technology. Various natural polymers have been employed to fabricate nanoparticles as a delivery vehicle for insulin oral administration. Chitosan, a natural polymer, is extensively studied due to the attractive properties, such as biodegradability, biocompatibility, bioactivity, nontoxicity and polycationic nature. Numerous studies were conducted to evaluate chitosan and chitosan derivatives-based nanoparticles capabilities for oral insulin delivery. This review highlights strategies that have been applied in the recent five years to fabricate chitosan/chitosan derivatives-based nanoparticles for oral insulin delivery. A summary of the barriers hurdle insulin absorption rendering its low bioavailability such as physical, chemical and enzymatic barriers are highlighted with an emphasis on the most common methods of chitosan nanoparticles preparation. Nanocarriers are able to improve the absorption of insulin through GIT, deliver insulin to the blood circulation and lower blood glucose levels. In spite of some drawbacks encountered in this technology, chitosan and chitosan derivatives-based nanoparticles are greatly promising entities for oral insulin delivery.

Textile dyes loaded chitosan nanoparticles: Characterization, biocompatibility and staining capacity

Textile dyeing is a hazardous and toxic process. While traditionally it has been managed through effluent treatment, new approaches focused upon improving the dyeing process are gaining relevance. In this work, we sought to obtain, for the first time, an eco-friendly chitosan-nanoparticle based textile dyeing method. To that end, yellow everzol and navy blue itosperse loaded chitosan nanoparticles were produced and their capacity to dye textiles and cytotoxicity towards human skin cells were evaluated. The results obtained showed that it was possible to obtain nanoencapsulated dyes through ionic gelation with an average entrapment efficacy above 90 %. Nanoparticles presented a positive surface charge and sizes between 190 and 800 nm with yellow everzol NPs occurring via ionic interactions while navy blue itosperse NPs were formed through hydrogen bonds. Furthermore, the produced dye NPs presented no cytotoxicity towards HaCat cells and presented staining percentages reaching 17.60 % for a viscose/wool blend.

Characteristics, Cryoprotection Evaluation and In Vitro Release of BSA-Loaded Chitosan Nanoparticles

Chitosan nanoparticles (CS-NPs) are under increasing investigation for the delivery of therapeutic proteins, such as vaccines, interferons, and biologics. A large number of studies have been taken on the characteristics of CS-NPs, and very few of these studies have focused on the microstructure of protein-loaded NPs. In this study, we prepared the CS-NPs by an ionic gelation method, and bovine serum albumin (BSA) was used as a model protein. Dynamic high pressure microfluidization (DHPM) was utilized to post-treat the nanoparticles so as to improve the uniformity, repeatability and controllability. The BSA-loaded NPs were then characterized for particle size, Zeta potential, morphology, encapsulation efficiency (EE), loading capacity (LC), and subsequent release kinetics. To improve the long-term stability of NPs, trehalose, glucose, sucrose, and mannitol were selected respectively to investigate the performance as a cryoprotectant. Furthermore, trehalose was used to obtain re-dispersible lyophilized NPs that can significantly reduce the dosage of cryoprotectants. Multiple spectroscopic techniques were used to characterize BSA-loaded NPs, in order to explain the release process of the NPs in vitro. The experimental results indicated that CS and Tripolyphosphate pentasodium (TPP) spontaneously formed the basic skeleton of the NPs through electrostatic interactions. BSA was incorporated in the basic skeleton, adsorbed on the surface of the NPs (some of which were inlaid on the NPs), without any change in structure and function. The release profiles of the NPs showed high consistency with the multispectral results.

In Vitro Evaluation of Curcumin-Encapsulated Chitosan Nanoparticles against Feline Infectious Peritonitis Virus and Pharmacokinetics Study in Cats

Feline infectious peritonitis (FIP) is an important feline viral disease, causing an overridden inflammatory response that results in a high mortality rate, primarily in young cats. Curcumin is notable for its biological activities against various viral diseases; however, its poor bioavailability has hindered its potential in therapeutic application. In this study, curcumin was encapsulated in chitosan nanoparticles to improve its bioavailability. Curcumin-encapsulated chitosan (Cur-CS) nanoparticles were synthesised based on the ionic gelation technique and were spherical and cuboidal in shape, with an average particle size of 330 nm and +42 mV in zeta potential. The nanoparticles exerted lower toxicity in Crandell-Rees feline kidney (CrFK) cells and enhanced antiviral activities with a selective index (SI) value three times higher than that of curcumin. Feline-specific bead-based multiplex immunoassay and qPCR were used to examine their modulatory effects on proinflammatory cytokines, including tumour necrosis factor (TNF)α, interleukin- (IL-) 6, and IL-1β. There were significant decrements in IL-1β, IL-6, and TNFα expression in both curcumin and Cur-CS nanoparticles. Based on the multiplex immunoassay, curcumin and the Cur-CS nanoparticles could lower the immune-related proteins in FIP virus (FIPV) infection. The single- and multiple-dose pharmacokinetics profiles of curcumin and the Cur-CS nanoparticles were determined by high-performance liquid chromatography (HPLC). Oral delivery of the Cur-CS nanoparticles to cats showed enhanced bioavailability with a maximum plasma concentration (C _max) value of 621.5 ng/mL. Incorporating chitosan nanoparticles to deliver curcumin improved the oral bioavailability and antiviral effects of curcumin against FIPV infection. This study provides evidence for the potential of Cur-CS nanoparticles as a supplementary treatment of FIP.

PEGylation and folate conjugation effects on the stability of chitosan-tripolyphosphate nanoparticles

Chitosan-based nanoparticles (Ch-NPs) prepared via ionotropic gelation of Ch with sodium tripolyphosphate (TPP) have been widely examined as potential drug carriers. Yet, recent studies have shown these particles to be unstable in model (pH 7.2-7.4) physiological media. To this end, here we explored the possibility of improving TPP-crosslinked Ch-NP stability through chemical Ch modification. Specifically, Ch samples with either 76% or 92% degrees of deacetylation (DD) were grafted with either polyethylene glycol (PEG), a hydrophilic molecule, or folic acid (F), a hydrophobic molecule. Limited variation in dispersion light scattering intensity, particle size and apparent ζ-potential, and lack of macroscopic precipitation were chosen as analytical evidence of dispersion stability. TPP titrations were performed to determine the optimal TPP:glucosamine molar ratio for preparing particles with near 200-nm diameters, which are desirable for systemic administration of drugs, cellular uptake, and enhancing NP blood circulation. Both DD and Ch modification influenced the particle formation process and the evolution in NP size and ζ-potential upon 30-day storage in virtually salt-free water at 25 °C and 37 °C, where the NPs underwent partial aggregation (along with possible dissolution and swelling) but remained colloidally dispersed. Under model physiological (pH 7.2; 163 mM ionic strength) conditions, however (where the chitosan amine groups were largely deprotonated), the particles quickly became destabilized, evidently due to particle dissolution followed by Ch precipitation. Overall, within the degrees of substitution used for this work (~1% for PEG, and 3 and 6% for F), neither PEG nor F qualitatively improved Ch-NP stability at physiological pH 7.2 conditions. Thus, application of TPP-crosslinked Ch-NPs in drug delivery (even when Ch is derivatized with PEG or F) should likely be limited to administration routes with acidic pH (at which these NPs remain stable).

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.

5-Fluorouracil monodispersed chitosan microspheres: Microfluidic chip fabrication with crosslinking, characterization, drug release and anticancer activity

Different size and morphology monodispersed chitosan (CS) microspheres loaded with the anticancer drug of 5-fluorouracil (5-Fu) were prepared by the microfluidic method assisted by a crosslinking unit with crosslinkers of tripolyphosphate (TPP) and glutaraldehyde (GTA). The sizes, morphologies, drug loading, encapsulation efficiency, drug release and cytotoxicity of 5-Fu loaded CS microspheres were characterized and determined. Results indicated that the CS microspheres were uniform in size distributions. They possessed excellent encapsulation efficiency and drug loading. The TPP-crosslinked CS microspheres had rough surfaces and exhibited faster drug release, whereas the CS microspheres crosslinked with GTA had smooth surfaces and showed slower drug release. Furthermore, 5-Fu-loaded CS microspheres exhibited sustained drug release which well fitted the first-order kinetics model and were pH-responsive in that the drug cumulative release was greater at acidic environments than at neutral conditions. Finally, 5-Fu loaded CS microspheres provided sufficient cytotoxicity and were satisfactory in the cancer cell inhibition.

Nanoparticles Based on Hydrophobic Polysaccharide Derivatives-Formation Principles, Characterization Techniques, and Biomedical Applications

Polysaccharide (PS) nanoparticles (NP) are fascinating materials that combine huge application potential with the unique beneficial features of natural biopolymers. Different types of PS-NP can be distinguished depending on the basic preparation principles (top-down vs bottom-up vs coating of nanomaterials) and the material from which they are obtained (native PS vs chemically modified PS derivatives vs nanocomposites). This review provides a comprehensive overview of an approach towards PS-NP that has gained rapidly increasing interest within the last decade; the nanoself-assembling of hydrophobic PS derivatives. This facile process is easy to perform and offers a broad structural diversity in terms of the PS backbone and the additional functionalities that can be introduced. Fundamental principles of different NP preparation techniques along with useful characterization methods are presented in this work. A comprehensive summary of PS-NP prepared by different techniques and with various PS backbones and types/amounts of hydrophobic substituents is given. The intention is to demonstrate how different parameters determine the size, size distribution, and zeta-potential of the particles. Moreover, application trends in biomedical areas are highlighted in which tailored functional PS-NP are evaluated and constantly developed further.

Production and Characterization of Chitosan-Polyanion Nanoparticles by Polyelectrolyte Complexation Assisted by High-Intensity Sonication for the Modified Release of Methotrexate

A promising strategy to improve the effectivity of anticancer treatment and decrease its side effects is to modulate drug release by using nanoparticulates (NPs) as carriers. In this study, methotrexate-loaded chitosan-polyanion nanoparticles were produced by polyelectrolyte complexation assisted by high-intensity sonication, using several anionic polymers, such as the sodium and potassium salts of poly(maleic acid-alt-ethylene) and poly(maleic acid-alt-octadecene), here named PAM-2 and PAM-18, respectively. Such NPs were analyzed and characterized according to particle size, polydispersity index, zeta potential and encapsulation efficiency. Likewise, their physical stability was tested at 4 °C and 40 °C in order to evaluate any change in the previously mentioned particle parameters. The in vitro methotrexate release was assessed at a pH of 7.4, which simulated physiological conditions, and the data were fitted to the heuristic models of order one, Higuchi, Peppas-Sahlin and Korsmeyer-Peppas. The results revealed that most of the MTX-chitosan-polyanion NPs have positive zeta potential values, sizes <280 nm and monodisperse populations, except for the NPs formed with PAM-18 polyanions. Further, the NPs showed adequate physical stability, preventing NP-NP aggregation. Likewise, these carriers modified the MTX release by an anomalous mechanism, where the NPs formed with PAM-2 polymer led to a release mechanism controlled by diffusion and relaxation, whereas the NPs formed with PAM-18 led to a mainly diffusion-controlled release mechanism.

Synthesis, Characterisation and Biological Evaluation of Ampicillin-Chitosan-Polyanion Nanoparticles Produced by Ionic Gelation and Polyelectrolyte Complexation Assisted by High-Intensity Sonication

Recently, one of the promising strategies to fight sensitive and resistant bacteria, and decrease the morbidity and mortality rates due to non-nosocomial infections, is to use antibiotic-loaded nanoparticles. In this study, ampicillin-loaded chitosan-polyanion nanoparticles were produced through the techniques of ionic gelation and polyelectrolyte complexation assisted by high-intensity sonication, using several crosslinking agents, including phytic acid (non-polymeric polyanion), sodium and potassium salts of poly(maleic acid-alt-ethylene) and poly(maleic acid-alt-octadecene) (polymeric polyanions). These nanoparticles were analysed and characterised in terms of particle size, polydispersity index, zeta potential and encapsulation efficiency. The stability of these nanosystems was carried out at temperatures of 4 and 40 °C, and the antimicrobial effect was determined by the broth microdilution method using sensitive and resistant Staphylococcus aureus strains. The results reveal that most of the nanosystems have sizes <220 nm, positive zeta potential values and a monodisperse population, except for the nanoparticles crosslinked with PAM-18 polyanions. The nanometric systems exhibited adequate stability preventing aggregation and revealed a two-fold increase in antimicrobial activity when compared with free ampicillin. This study demonstrates the potential application of synthesised nanoparticles in the field of medicine, especially for treating infections caused by pathogenic S. aureus strains.

Single-Step Self-Assembly and Physical Crosslinking of PEGylated Chitosan Nanoparticles by Tannic Acid

Chitosan-based nanoparticles are promising materials for potential biomedical applications. We used Flash NanoPrecipitation as a rapid, scalable, single-step method to achieve self-assembly of crosslinked chitosan nanoparticles. Self-assembly was driven by electrostatic interactions, hydrogen bonding, and hydrophobic interactions; tannic acid served to precipitate chitosan to seed nanoparticle formation and crosslink the chitosan to stabilize the resulting particles. The size of the nanoparticles can be tuned by varying formulation parameters including the total solids concentration and block copolymer to core mass ratio. We demonstrated that hydrophobic moieties can be incorporated into the nanoparticle using a lipophilic fluorescent dye as a model system.

pH-Sensitive Chitosan-Sodium Phytate Core-Shell Hollow Beads and Nanocapsules for the Encapsulation of Active Ingredients

The oral administration of nutraceuticals and vitamins is the most compliant route because of its minimal invasiveness, painlessness, ease of use, and cost effectiveness. To overcome the possible destruction and low availability induced by the harsh gastrointestinal environment, we use sodium phytate as a cross-linker to fabricate pH-sensitive core-shell chitosan hollow beads and nanocapsules through the ionic linking method for the controllable release of active ingredients. Texture profile analysis, transmission electron microscopy, dynamic light scattering, and scanning electron microscopy were used to characterize the morphologies and behaviors of the beads and nanocapsules. The size of the beads could be adjusted from 0.1 to 10 mm, and the diameter of the nanocapsules was 50-100 nm. The addition of pectin in sodium phytate remarkably increased the hardness of the chitosan beads. Nile blue A was used as a model active ingredient for loading into the chitosan beads with the maximum encapsulation efficiency (EE) and loading capacity of 96.07 ± 2.45% and 9.61 ± 0.29%, respectively. Polyphenols including catechin, epicatechin, epigallocatechin-3-gallate, and proanthocyanidin were successfully loaded into the chitosan nanocapsules with an EE of above 90%. The cumulative release of Nile blue A from the beads at pH 1.2 (after 2 h) and pH 6.8 (after 6 h) was less than 20% and more than 80%, respectively. Similarly, the cumulative release of polyphenols in the nanocapsules at pH 1.2 (after 2 h) and pH 6.8 (after 6 h) was less than 30% and more than 70%, respectively. In sum, chitosan-sodium phytate with and without pectin could form pH-responsive macro- and nanoscale carriers suitable for the encapsulation and controlled release of active ingredients.

A green approach to fabricating nacre-inspired nanocoating for super-efficiently fire-safe polymers via one-step self-assembly

Developing a high efficient, environmental-friendly and universal fire-safe strategy for combustible polymers is crucial but challengeable. Inspired by nacre, we developed a super-efficiently fire-safe nanocoating based on carboxymethyl chitosan (CCS) and modified montmorillonite (MMT) via one-step self-assembly. The nanocoating possessed well-arranged nacre-like hierarchical microstructure, exhibiting high transparency and specific nacre-like iridescence. More importantly, the nanocoating endowed many large-scale polymer substrates, such as polyester film, cotton fabric and polyurethane foam, with super-efficient fire-safety by dip-coating or spray-coating. All the coated substrates were self-extinguished in the burning tests. Meanwhile, their heat release and smoke production were decreased remarkably. Most notably, the peak heat release rate, total heat release, peak smoke production rate and total smoke production of polyurethane foam were decreased by 84.1%, 89.4%, 84.4% and 95.2%, respectively. Additionally, no organic solvent, halogen and phosphorus element were involved, which was environmental-friendly. Our findings provide a super-efficient, economical, universal and green fabrication strategy for fire-safe polymers.

Molecular simulation and in vitro evaluation of chitosan nanoparticles as drug delivery systems for the controlled release of anticancer drug cytarabine against solid tumours

The present work is an attempt to integrate the molecular simulation studies with in vitro cytotoxicity of cytarabine-loaded chitosan nanoparticles and exploring the potential of this formulation as therapeutics for treating solid tumours. The molecular simulation was performed using GROMACS v5.4 in which, chitosan polymer (CHT; six molecules) was used to study the encapsulation and release of a single molecule of cytarabine. Root Mean Square Deviation (RMSD) of the Cα atom of cytarabine (CBR) molecule shows that CBR starts to diffuse out of the CHT polymer binding pocket around 10.2 ns, indicated by increased fluctuation of RMSD at pH 6.4, while the drug diffusion is delayed at pH 7.4 and starts diffusing around 17.5 ns. Cytarabine-loaded chitosan nanoparticles (CCNP), prepared by ionic gelation method were characterized for encapsulation efficiency, particle size and morphology, zeta potential, crystallinity and drug release profile at pH 6.4 and 7.4. CCNPs showed 64% encapsulation efficiency with an average diameter of 100 nm and zeta potential of + 53.9 mV. It was found that cytarabine existed in amorphous state in nanoformulation. In vitro release studies showed 70% cytarabine was released from the chitosan-based nanoformulation release at pH 6.4, which coincides with the pH of tumour microenvironment. Cytotoxicity against breast cancer cell line (MCF 7) was higher for nanoformulation compared to free cytarabine. Haemocompatibility studies showed that chitosan-based nanoformulation is safe, biocompatible and nonhaemolytic in nature; hence, can be used as a safe drug delivery system. Taken together, our study suggests that chitosan nanoformulation would be an effective strategy for the pH-dependent release of cytarabine against solid tumours and might impart better therapeutic efficiency.

Fabrication of Quaternized Chitosan Nanoparticles Using Tripolyphosphate/Genipin Dual Cross-Linkers as a Protein Delivery System

Various amounts of 2-((acryloyloxy)ethyl)trimethylammonium chloride were grafted onto chitosan (CS) via redox polymerization method to obtain water-soluble quaternized CS (QCS). The QCS nanoparticles loaded with bovine serum albumin (BSA) were then produced by ionic gelation with tripolyphosphate (TPP) and further covalently cross-linked with genipin. The formation of QCS nanoparticles was optimized as a function of monomer grafting yield, QCS/TPP weight ratio, and QCS/genipin weight ratio by Box-Behnken design and response surface methodology. The results showed that QCS nanoparticles prepared with a grafting yield of 50%, QCS/TPP weight ratio of 7.67, and QCS/genipin weight ratio of 60 had a particle size of 193.68 ± 44.92 nm, polydispersity of 0.232, zeta potential of +23.97 mV and BSA encapsulation efficiency of 46.37 ± 2.89%, which were close to the predicted values from mathematical models. In vitro drug release studies at pH 1.2 and pH 7.4 exhibited that the release rate of BSA was significantly decreased and the release period was significantly prolonged after QCS nanoparticles cross-linking with genipin. Therefore, QCS nanoparticles cross-linked with TPP/genipin dual cross-linkers may be a promising protein drug carrier for a prolonged and sustained delivery.

A biotechnological approach to immunotherapy: Antivenom against Crotalus durissus cascavella snake venom produced from biodegradable nanoparticles

Snakebite envenoming is a tropical disease neglected worldwide. In Brazil, the Crotalus durissus cascavella (CDC) snake belongs to a genus with venom of highest lethality. A search for new immunoadjuvants aimed to expand the therapeutic alternatives to improve vaccines and antivenom. This approach proposed to produce small and narrow-sized cationic CDC venom-loaded chitosan nanoparticles (CHNP) able to induce antibody response against the CDC venom. The ionic gelation method induced the formation of stable and slightly smooth spherical nanoparticles (<160 nm) with protein loading efficiency superior to 90%. The interactions between venom proteins and CHNP assessed using FT-IR spectroscopy corroborated with the in vitro release behavior of proteins from nanoparticles. Finally, the immunization animal model using BALB/c mice demonstrated the higher effectiveness of CDC venom-loaded CHNP compared to aluminum hydroxide, a conventional immunoadjuvant. Thus, CHNPs loaded with CDC venom exhibited a promising biotechnological approach to immunotherapy.

Plasticizing of chitosan films with deep eutectic mixture of malonic acid and choline chloride

Chitosan (CS) films containing deep eutectic solvent (DES) based on malonic acid (MA) and choline chloride (ChCl) were successfully prepared by solution casting method by using DES content ranging from 0 to 82 wt%. A strong interaction of CS with the components of DES was demonstrated by analyses of water sorption isotherms, atomic force microscopy and FTIR results. The plasticizing effect of the MA and ChCl mixture on the CS matrix was shown by static bulk mechanical measurements, thermal analysis and quantitative nanomechanical mapping (QNM). Elongation at break increased from 3 to 62% at increase of DES content from 0 to 67 wt%, while further increase of DES content led to the decreasing of maximal elongation. Introduction of DES into CS films led to the appearance of glass transition temperature in the region +2 - -2.3 °C. QNM results indicated homogeneity of the films containing up to 75 wt% of DES.

Biomedical Applications of Chitosan and Its Derivative Nanoparticles

Chitosan is a biodegradable natural polymer with many advantages such as nontoxicity, biocompatibility, and biodegradability. It can be applied in many fields, especially in medicine. As a delivery carrier, it has great potential and cannot be compared with other polymers. Chitosan is extremely difficult to solubilize in water, but it can be solubilized in acidic solution. Its insolubility in water is a major limitation for its use in medical applications. Chitosan derivatives can be obtained by chemical modification using such techniques as acylation, alkylation, sulfation, hydroxylation, quaternization, esterification, graft copolymerization, and etherification. Modified chitosan has chemical properties superior to unmodified chitosan. For example, nanoparticles produced from chitosan derivatives can be used to deliver drugs due to their stability and biocompatibility. This review mainly focuses on the properties of chitosan, chitosan derivatives, and the origin of chitosan-based nanoparticles. In addition, applications of chitosan-based nanoparticles in drug delivery, vaccine delivery, antimicrobial applications, and callus and tissue regeneration are also presented. In summary, nanoparticles based on chitosan have great potential for research and development of new nano vaccines and nano drugs in the future.

Polymer-Based Nanomaterials and Applications for Vaccines and Drugs

Nanotechnology plays a significant role in drug development. As carriers, polymeric nanoparticles can deliver vaccine antigens, proteins, and drugs to the desired site of action. Polymeric nanoparticles with lower cytotoxicity can protect the delivered antigens or drugs from degradation under unfavorable conditions via a mucosal administration route; further, the uptake of nanoparticles by antigen-presenting cells can increase and induce potent immune responses. Additionally, nanomaterials are widely used in vaccine delivery systems because nanomaterials can make the vaccine antigen long-acting. This review focuses on some biodegradable polymer materials such as natural polymeric nanomaterials, chemically synthesized polymer materials, and biosynthesized polymeric materials, and points out the advantages and the direction of research on degradable polymeric materials. The application and future perspectives of polymeric materials as delivery carriers and vaccine adjuvants in the field of drugs and vaccines are presented. With the increase of knowledge and fundamental understandings of polymer-based nanomaterials, means of integrating some other attractive properties, such as slow release, target delivery, and alternative administration methods and delivery pathways are feasible. Polymer-based nanomaterials have great potential for the development of novel vaccines and drug systems for certain needs, including single-dose and needle-free deliveries of vaccine antigens and drugs in the future.

Facile, shear-induced, rapid formation of stable gels of chitosan through in situ generation of colloidal metal salts

A novel method of preparing chitosan gels using in situ generated negatively-charged colloidal salts of a variety of metal ions is described.

Improved Chemical Stability and Antiproliferative Activities of Curcumin-Loaded Nanoparticles with a Chitosan Chlorogenic Acid Conjugate

A chitosan (CS)-chlorogenic acid (CA) conjugate was successfully prepared through free-radical-induced protocols with a substitution of CA on CS of 103.5 mg/g. ATR-FTIR and ¹H NMR results validated the covalent conjugation of CA onto CS. XRD results indicated the decrease of crystallinity after CA conjugation. DPPH-scavenging activity and reducing-power studies indicated that the CS-CA conjugate had stronger antioxidant activity than chitosan. The particle diameters of curcumin-loaded CS and CS-CA nanoparticles simultaneously formed by ionic gelling in the presence of tripolyphosphate (TPP) were less than 300 nm (243.6 and 256.5 nm, respectively), and zeta-potential values between 25 and 30 mV were obtained. TEM results showed that the nanoparticles were spherically shaped and homogeneously dispersed. Curcumin with the CS-CA conjugate showed better heat stability than with CA at both temperatures (25 and 95 °C) (p <0.05). Curcumin release was inhibited by the CS-CA conjugate. The total release amount of curcumin from CS and CS-CA-conjugate nanoparticles were 70.5 and 61.7%, respectively (p <0.05). A methyl thiazolyl tetrazolium (MTT) assay showed that the antiproliferative activity of curcumin in CS-CA nanoparticles was remarkably higher than that in CS nanoparticles because of the higher chemical stability. The results suggest that CS-CA-based nanoparticles are promising candidates for the encapsulation and controlled release of hydrophobic, bioactive compounds and can improve these compounds' chemical stabilities and anticancer activities.

Zinc-Modified Nanotransporter of Doxorubicin for Targeted Prostate Cancer Delivery

This work investigated the preparation of chitosan nanoparticles used as carriers for doxorubicin for targeted cancer delivery. Prepared nanocarriers were stabilized and functionalized via zinc ions incorporated into the chitosan nanoparticle backbone. We took the advantage of high expression of sarcosine in the prostate cancer cells. The prostate cancer targeting was mediated by the AntiSar antibodies decorated surface of the nanocage. Formation of the chitosan nanoparticles was determined using a ninhydrin assay and differential pulse voltammetry. Obtained results showed the strong effect of tripolyphosphine on the nanoparticle formation. The zinc ions affected strong chitosan backbone coiling both in inner and outer chitosan nanoparticle structure. Zinc electrochemical signal depended on the level of the complex formation and the potential shift from -960 to -950 mV. Formed complex is suitable for doxorubicin delivery. It was observed the 20% entrapment efficiency of doxorubicin and strong dependence of drug release after 120 min in the blood environment. The functionality of the designed nanotransporter was proven. The purposed determination showed linear dependence in the concentration range of Anti-sarcosine IgG labeled gold nanoparticles from 0 to 1000 µg/mL and the regression equation was found to be y = 3.8x - 66.7 and R² = 0.99. Performed ELISA confirmed the ability of Anti-sarcosine IgG labeled chitosan nanoparticles with loaded doxorubicin to bind to the sarcosine molecule. Observed hemolytic activity of the nanotransporter was 40%. Inhibition activity of our proposed nanotransporter was evaluated to be 0% on the experimental model of S. cerevisiae. Anti-sarcosine IgG labeled chitosan nanoparticles, with loaded doxorubicin stabilized by Zn ions, are a perspective type of nanocarrier for targeted drug therapy managed by specific interaction with sarcosine and metallothionein for prostate cancer.

Enhancing Mucosal Immune Response of Newcastle Disease Virus DNA Vaccine Using N-2-Hydroxypropyl Trimethylammonium Chloride Chitosan and N,O-Carboxymethyl Chitosan Nanoparticles as Delivery Carrier

Because mucosal sites are the entry ports of pathogens, immunization via mucosal routes can extremely enhance the immunity. To elevate the potential of N-2-hydroxypropyl trimethylammonium chloride chitosan (N-2-HACC) and N,O-carboxymethyl chitosan (CMC) nanoparticles as a mucosal immune delivery carrier for DNA vaccines, we prepared the NDV F gene plasmid DNA with C3d6 molecular adjuvant (pVAX I-F(o)-C3d6) encapsulated in the N-2-HACC-CMC nanoparticles (N-2-HACC-CMC/pFDNA-C3d6 NPs). The N-2-HACC-CMC/pFDNA-C3d6 NPs had regular spherical morphology and low toxicity with a mean diameter of 309.7 ± 6.52 nm, zeta potential of 49.9 ± 4.93 mV, encapsulation efficiency of 92.27 ± 1.48%, and loading capacity of 50.75 ± 1.35%. The N-2-HACC-CMC had high stability and safety. The pVAX I-F(o)-C3d6 could be sustainably released from the N-2-HACC-CMC/pFDNA-C3d6 NPs after an initial burst release. Immunization intranasally of chickens with N-2-HACC-CMC/pFDNA-C3d6 NPs not only produced higher anti-NDV IgG and sIgA antibody than chickens in other groups did, but also significantly stimulated lymphocyte proliferation and triggered higher the IL-2, IL-4, and IFN-γ levels. These findings indicated that the N-2-HACC-CMC could be used as an efficient delivery carrier for the mucosal immunity of Newcastle disease virus DNA vaccine. The work laid a basis for the quaternized chitosan nanoparticles as efficient mucosal immunity delivery carrier for DNA vaccines and had immense application promise and potential for vaccines and drugs.