Preparation and Characterization of Chitosan-Based Nanoparticles

Bioactive peptides/chitosan nanoparticles enhance cellular antioxidant activity of (-)-epigallocatechin-3-gallate

(-)-Epigallocatechin-3-gallate (EGCG), one representative of the well-studied chemopreventive phytochemicals but with low bioavailability, was encapsulated in monodispersed nanoparticles that were assembled from bioactive caseinophosphopeptide (CPP) and chitosan (CS). The encapsulation efficiency of EGCG in CS-CPP nanoparticles ranged from 70.5 to 81.7%; meanwhile, the in vitro release of EGCG from CS-CPP nanoparticles was in a controllable manner. The EGCG-loaded CS-CPP nanoparticles exerted stronger activity of scavenging free radical than the free EGCG (p < 0.01) in the cellular antioxidant activity assay. Furthermore, cellular uptake of the EGCG-loaded CS-CPP nanoparticles was confirmed by the green fluorescence inside the human hepatocellular caricinoma (HepG2) cells, which was considered to play an important role in the improvement of the antioxidant activity of the nanoencapsulated EGCG. The results suggested that encapsulation of EGCG using CS-CPP nanoparticles should be a potential approach to enhance its antioxidant activity in biological systems.

Biopolymer-based nanoparticles for drug/gene delivery and tissue engineering

There has been a great interest in application of nanoparticles as biomaterials for delivery of therapeutic molecules such as drugs and genes, and for tissue engineering. In particular, biopolymers are suitable materials as nanoparticles for clinical application due to their versatile traits, including biocompatibility, biodegradability and low immunogenicity. Biopolymers are polymers that are produced from living organisms, which are classified in three groups: polysaccharides, proteins and nucleic acids. It is important to control particle size, charge, morphology of surface and release rate of loaded molecules to use biopolymer-based nanoparticles as drug/gene delivery carriers. To obtain a nano-carrier for therapeutic purposes, a variety of materials and preparation process has been attempted. This review focuses on fabrication of biocompatible nanoparticles consisting of biopolymers such as protein (silk, collagen, gelatin, β-casein, zein and albumin), protein-mimicked polypeptides and polysaccharides (chitosan, alginate, pullulan, starch and heparin). The effects of the nature of the materials and the fabrication process on the characteristics of the nanoparticles are described. In addition, their application as delivery carriers of therapeutic drugs and genes and biomaterials for tissue engineering are also reviewed.

Functional enhancement of chitosan and nanoparticles in cell culture, tissue engineering, and pharmaceutical applications

As a biomaterial, chitosan has been widely used in tissue engineering, wound healing, drug delivery, and other biomedical applications. It can be formulated in a variety of forms, such as powder, film, sphere, gel, and fiber. These features make chitosan an almost ideal biomaterial in cell culture applications, and cell cultures arguably constitute the most practical way to evaluate biocompatibility and biotoxicity. The advantages of cell cultures are that they can be performed under totally controlled environments, allow high throughput functional screening, and are less costly, as compared to other assessment methods. Chitosan can also be modified into multilayer composite by combining with other polymers and moieties to alter the properties of chitosan for particular biomedical applications. This review briefly depicts and discusses applications of chitosan and nanoparticles in cell culture, in particular, the effects of chitosan and nanoparticles on cell adhesion, cell survival, and the underlying molecular mechanisms: both stimulatory and inhibitory influences are discussed. Our aim is to update the current status of how nanoparticles can be utilized to modify the properties of chitosan to advance the art of tissue engineering by using cell cultures.

Highly biocompatible multi-walled carbon nanotube-chitosan nanoparticle hybrids as protein carriers

Carbon nanotube (CNT)-organic polymer hybrids have important potential applications in the immobilization of therapeutic biomolecules. Recently developed CNT-organic polymer composites require the use of organic solvents for their preparation and have limited polymer functionalization. To address these limitations, multi-walled CNT (MWCNT)-chitosan nanoparticle (CS NP) hybrids have been synthesized in situ by an ionotropic gelation process, which is extremely mild and involves the mixture of two aqueous solutions at room temperature. The MWCNT-CS NP hybrids were characterized by atomic force microscopy and thermogravimetric analysis. Under optimal conditions the CS NP can be tethered to the MWCNT surface in high density and with relatively uniform coverage. The MWCNT-CS NP hybrids show good dispersibility and stability in aqueous solutions. In order to evaluate the potential utilization of the hybrids as protein carries the cytotoxicity to HeLa cells and protein immobilization (of bovine serum albumin (BSA), used here as a model) capacity of the hybrids were investigated in detail. The results demonstrate that the MWCNT-CS NP hybrids are biocompatible at concentrations up to 100 μg mL(-1) for 24 h incubation. The MWCNT-CS NP hybrids improve the BSA immobilization efficiency 0.8 times and simultaneously decrease the cellular toxicity by about 50% compared with carboxylated MWCNT.

In situ formation of chitosan-cyclodextrin nanospheres for drug delivery

Chitosan-cyclodextrin nanospheres were prepared by in situ formation through Michael addition between N-maleated chitosan (NMC) and per-6-thio-β-cyclodextrin sodium salt in an aqueous medium. This facile preparation method did not involve any organic solvent and surfactant. Through adjusting the preparation conditions, the nanospheres with a relatively narrow size distribution could be obtained. The obtained nanospheres were characterized by TEM and particle size analyzer. Doxorubicin hydrochloride (DOX·HCl), a water soluble anticancer drug, was loaded in the nanospheres with a high encapsulation efficiency. The in vitro drug release showed that the release of DOX·HCl from the nanospheres could be effectively sustained. The cytotoxicity evaluation showed the drug loaded nanospheres exhibited efficient inhibition on HeLa cells.

Electrospray fabrication of doxorubicin-chitosan-tripolyphosphate nanoparticles for delivery of doxorubicin

This work focused on a new technique for the preparation of doxorubicin (DOX) loaded chitosan (CS) nanoparticles (DOX-CS) - formation by electrospray ionization in the presence of tripolyphosphate (TPP) as the stabilizer. The working distance, needle gauge, flow rate, stirring rate, electrospraying voltage and DOX to CS molar ratio were sequentially and individually optimized and found to be a 26 gauge needle, an applied voltage of 13 kV, a flow rate of 0.5 mL/h, a working distance of 8 cm and a stirring rate of 400 rpm. The incorporation of chemically unchanged DOX with the CS into the particles was ascertained by Fourier transformed infrared spectroscopy (FT-IR), differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). Under these optimized conditions, the DOX-CS particles were found to be nanoparticles of approximately 300-570 (dry particles) or 530-870 nm diameter (hydrated particles), with a PDI and SPAN polydispersity indices of 0.97-0.82 and 0.62-0.64, respectively, for initial DOX loading levels of 0.25-1%, as determined by SEM and particle size analyzer, respectively. Moreover, a high encapsulation efficiency (EE) of DOX into the nanoparticles was attained, ranging from 63.4 to 67.9% EE at 1 to 0.25% DOX loading. Finally, the in vitro DOX release behaviors of the DOX-CS particles revealed a prolonged release of DOX over at least seven hours.

Recent advances of chitosan nanoparticles as drug carriers

Chitosan nanoparticles are good drug carriers because of their good biocompatibility and biodegradability, and can be readily modified. As a new drug delivery system, they have attracted increasing attention for their wide applications in, for example, loading protein drugs, gene drugs, and anticancer chemical drugs, and via various routes of administration including oral, nasal, intravenous, and ocular. This paper reviews published research on chitosan nanoparticles, including its preparation methods, characteristics, modification, in vivo metabolic processes, and applications.

Photosensitive nanoparticles of chitosan complex for controlled release of dye molecules

Photosensitive nanoparticles (NPs) were fabricated by employing chitosan hydrochloride (CHC) and photosensitive 4-oxo-4-(pyren-4-ylmethoxy) butanoic acid (PYBA) through ionic self-assembly. Transmission electron microscope (TEM) images showed that the average diameter of the complex NPs depended on the charge molar ratio of PYBA to CHC. The photosensitive properties of the NPs were investigated using (1)H NMR, optical photography, dynamic light scattering and TEM. As a model guest, Nile red dye was loaded in the photosensitive NPs. Under UV light or near infrared laser irradiation, the complex could be dissociated and shrank, so that loaded Nile red was released owing to the decomposition of chemical bonds in the photolabile chromophore groups. The results showed that 70% of the Nile red molecules were released from the NPs under a 1200 mW cm(-2) irradiation of UV light for 50 s. Moreover, the releasing rate of Nile red molecules could be adjusted by altering UV light intensity. Such a chitosan complex has potential applications in the design of photo-controlled guest delivery systems.

Targeted delivery of low molecular drugs using chitosan and its derivatives

Chitosan has prompted the continuous impetus for the development of safe and effective drug delivery systems because of its unique physicochemical and biological characteristics. The primary hydroxyl and amine groups located on the backbone of chitosan allow for chemical modification to control its physical properties. When the hydrophobic moiety is conjugated to a chitosan molecule, the resulting amphiphile may form self-assembled nanoparticles that can encapsulate a quantity of drugs and deliver them to a specific site of action. Chemical attachment of the drug to the chitosan throughout the functional linker may produce useful prodrugs, exhibiting the appropriate biological activity at the target site. Mucoadhesive and absorption enhancement properties of chitosan increase the in vivo residence time of the dosage form in the gastrointestinal tract and improve the bioavailability of various drugs. The main objective of this review is to provide an insight into various target-specific carriers, based on chitosan and its derivatives, towards low molecular weight drug delivery. The first part of the review is concerned with the organ-specific delivery of low molecular drugs using chitosan and its derivatives. The subsequent section considers the recent developments of drug delivery carriers for cancer therapy with special focus on various targeting strategies.

Sorption of Cu(II) complexes with ligands tartrate, glycine and quadrol by chitosan

The sorption by chitosan in Cu(II) solutions containing tartrate, glycine (amino acetic acid) and quadrol (N,N,N',N'-tetrakis(2-hydroxypropyl)ethylenediamine) as ligands has been investigated. The degree of sorbate removal strongly depends on pH. In solutions containing tartrate almost complete sorption of both Cu(II) and tartrate proceeds in mildly acidic and neutral solutions. The sorption of Cu(II) is also complete in alkaline solutions containing glycine; meanwhile a substantial sorption of glycine proceeds at pH approximately 6. The Cu(II) sorption in solutions containing quadrol is insignificant. Any sorption of quadrol does not proceed in the whole range of pH investigated. The investigations under equilibrium conditions showed that the Cu(II) sorption from tartrate containing solutions obeys Freundlich equation and in solutions containing glycine and quadrol it fits Langmuir equation. Supposedly, Cu(II) sorption onto chitosan proceeds with formation of amino complexes onto the surface of chitosan; the sorption of tartrate proceeds as electrostatic as well as with formation of amide bonds. Applying of electrolysis enables a complete removal of sorbed Cu(II) and ligands without changes in physical and chemical properties of chitosan. This is confirmed by sorption ability of regenerated chitosan, measurements of its molecular weight, the deacetylation degree and FT-IR spectra.

Surpassing the use of copper in the click functionalization of polymeric nanostructures: a strain-promoted approach

The limitations (depolymerization and Cu contamination) in the use of Cu(I)-catalyzed azide-alkyne [3 + 2] cycloadditions (CuAAC) for the selective click functionalization of polysaccharide-based systems have been efficiently surpassed using a strain-promoted approach (SPAAC). The SPAAC decoration of chitosan-g-poly(ethylene glycol) nanostructures with an immunoglobulin G under physiological conditions represents a step forward in the preparation of immunonanoparticles.

Ultra-small water-dispersible fluorescent chitosan nanoparticles: synthesis, characterization and specific targeting

A robust water-in-oil microemulsion method of making water-dispersible ultra-small (<30 nm) size fluorescent chitosan nanoparticles is reported for the first time and specific targeting of these FCNPs to human leukemia cells via aptamer recognition is demonstrated.

Polysaccharides-based nanoparticles as drug delivery systems

Natural polysaccharides, due to their outstanding merits, have received more and more attention in the field of drug delivery systems. In particular, polysaccharides seem to be the most promising materials in the preparation of nanometeric carriers. This review relates to the newest developments in the preparation of polysaccharides-based nanoparticles. In this review, four mechanisms are introduced to prepare polysaccharides-based nanoparticles, that is, covalent crosslinking, ionic crosslinking, polyelectrolyte complex, and the self-assembly of hydrophobically modified polysaccharides.

Use of dicarboxylic acids to improve and diversify the material properties of porous chitosan membranes

Several nontoxic dicarboxylic acid solutions (oxalic acid, succinic acid, malic acid, and adipic acid solutions) instead of an acetic acid solution were used as solvents for chitosan dissolution. The amount of free amino groups of the chitosan in the solution decreased due to the ionic cross-linking of the dicarboxylic acids with chitosan. These solutions were used to fabricate porous chitosan membranes. Replacing acetic acid with these dicarboxylic acids for membrane preparation improved the water uptake (by 35% at most), tensile strength (by 110% at most), and elongation capability (by 50% at most) of the membranes. These dicarboxylic acid solutions not only act as solvents but also improve the material properties of the chitosan membranes due to the ionic cross-linking and hydrogen bond formation. In brief, a nontoxic and straightforward cross-linking method has been developed for chitosan material; this method does not result in a brittle product, thus making it better than the use of toxic cross-linking reagents.

Polymeric nanoparticles for cancer therapy

Cancer is an ever-increasing menace that needs to be curbed soon. Though chemotherapy is successful to some extent, the main drawbacks of chemotherapy is the limited accessibility of drugs to the tumor tissues requiring high doses, their intolerable toxicity, development of multiple drug resistance and their non-specific targeting. Nanoparticles (NPs), an evolution of nanotechnology, have the potential to successfully address these problems related to drug delivery and retention and are considered potential candidates to carry drugs to the desired site of therapeutic action. In this review, we give an overview of the use of clinically applicable NPs mainly for cancer therapy. We also focus on the different types of nanoscale polymer carriers used for the delivery of chemotherapeutic agents and the mechanisms that facilitate their targeted delivery to tumor cells.

Preparation of chitosan nanoparticles using methacrylic acid

In this work the preparation of chitosan nanoparticle was investigated using methacrylic acid in different conditions and studied by particle size analyzer, zeta-potential, Fourier transform infrared spectroscopy (FT-IR), nuclear magnetic resonance (NMR) and transmission electron microscopy (TEM). The particle size was dependent on the chitosan concentration used during the preparation method. Nanoparticles with sizes as small as 60 nm were achieved, that can be extremely important for several applications. The nanoparticles solution was also pH-sensitive, due to swelling and aggregation of the nanoparticles. The nanoparticles obtained presented a very homogeneous morphology showing a quite uniform particles size distribution and a rather spherical shape.

Preparation and evaluation of chitosan/carrageenan beads for controlled release of sodium diclofenac

The polyelectrolyte complex (PEC) hydrogel beads based on chitosan (CS) and carrageenan (CR) have been studied as a controlled release device to deliver sodium diclofenac (DFNa) in the simulated gastrointestinal condition. Various factors potentially influencing the drug release (ie, CS/CR proportion, DFNa content, types and amount of cross-linking agents) were also investigated. The optimal formulation was obtained with CS/CR proportion of 2/1 and 5% (wt/vol) DFNa. The controlled release of the drug from this formulation was superior to other formulations and was able to maintain the release for approximately 8 hours. Upon cross-linking with glutaric acid and glutaraldehyde, the resulting beads were found to be more efficient for prolonged drug release than their non-cross-linking counterparts. The bead cross-linked with glutaraldehyde was able to control the release of the drug over 24 hours. The difference in the drug release behavior can be attributed to the differences in ionic interaction between the oppositely charged ions and to the concentrations of the drug within the beads, which depends on the compositions of the formulation and the pH of the dissolution medium. The release of drug was controlled by the mechanism of the dissolution of DFNa in the dissolution medium and the diffusion of DFNa through the hydrogel beads.