Heparin/chitosan nanoparticle carriers prepared by polyelectrolyte complexation

Preparation of chitosan nanoparticles for simultaneous drug delivery of dacarbazine and enoxaparin in melanoma

The aim of this study was to investigate the anti-melanoma and anti-angiogenic effects of enoxaparin surface-coated dacarbazine-loaded chitosan nanoparticles (Enox-Dac-Chi NPs). The prepared Enox-Dac-Chi NPs had a particle size of 367.95 ± 1.84 nm, zeta potential of -7.12 ± 0.25 mV, efficiency of drug loading (DL%) of 73.90 ± 3.84 %, and attached enoxaparin percentage of 98.53 ± 0.96 %. Both drugs had extended-release profiles and approximately 96 % of enoxaparin and 67 % dacarbazine were released within 8 h. The Enox-Dac-Chi NPs with IC₅₀ of 59.60 ± 1.25 μg/ml were the most cytotoxic against melanoma cancer cells compared with chitosan nanoparticles containing only dacarbazine (Dac-Chi NPs) and free dacarbazine. There was no significant difference between the cellular uptake of Chi NPs and enoxaparin coated Chi NPs (Enox-Chi NPs) in B16F10 cells. Enox-Chi NPs with an average anti-angiogenic score of 1.75 ± 0.125 had more anti-angiogenic effect than enoxaparin. The results showed that simultaneous delivery of dacarbazine and enoxaparin by chitosan nanoparticles can enhance the anti-melanoma effect of dacarbazine. Additionally, enoxaparin can prevent the melanoma metastasis by its anti-angiogenic activity. Thus, the designed nanoparticles can be introduced as effective drug delivery vehicles for the treatment and prevention of metastatic melanoma.

A Review of the Preparation, Characterization, and Applications of Chitosan Nanoparticles in Nanomedicine

Chitosan is a fibrous compound derived from chitin, which is the second most abundant natural polysaccharide and is produced by crustaceans, including crabs, shrimps, and lobsters. Chitosan has all of the important medicinal properties, including biocompatibility, biodegradability, and hydrophilicity, and it is relatively nontoxic and cationic in nature. Chitosan nanoparticles are particularly useful due to their small size, providing a large surface-to-volume ratio, and physicochemical properties that may differ from that of their bulk counterparts; thus, chitosan nanoparticles (CNPs) are widely used in biomedical applications and, particularly, as contrast agents for medical imaging and as vehicles for drug and gene delivery into tumors. Because CNPs are formed from a natural biopolymer, they can readily be functionalized with drugs, RNA, DNA, and other molecules to target a desired result in vivo. Furthermore, chitosan is approved by the United States Food and Drug Administration as being Generally Recognized as Safe (GRAS). This paper reviews the structural characteristics and various synthesis methods used to produce chitosan nanoparticles and nanostructures, such as ionic gelation, microemulsion, polyelectrolyte complexing, emulsification solvent diffusion, and the reverse micellar method. Various characterization techniques and analyses are also discussed. In addition, we review drug delivery applications of chitosan nanoparticles, including for ocular, oral, pulmonary, nasal, and vaginal methodologies, and applications in cancer therapy and tissue engineering.

Self-assembled FGF21 nanoparticles alleviate drug-induced acute liver injury

Acetaminophen (N-acetyl-p-aminophenol, APAP) is a common antipyretic agent and analgesic. An overdose of APAP can result in acute liver injury (ALI). Oxidative stress and inflammation are central to liver injury. N-acetylcysteine (NAC), a precursor of glutathione, is used commonly in clinical settings. However, the window of NAC treatment is limited, and more efficacious alternatives must be found. Endogenous cytokines such as fibroblast growth factor (FGF) 21 can improve mitochondrial function while decreasing intracellular oxidative stress and inflammatory responses, thereby exhibiting antioxidant-like effects. In this study, self-assembled nanoparticles comprising chitosan and heparin (CH) were developed to deliver FGF21 (CH-FGF21) to achieve the sustained release of FGF21 and optimize the in vivo distribution of FGF21. CH-FGF21 attenuated the oxidative damage and intracellular inflammation caused by APAP to hepatocytes effectively. In a murine model of APAP-induced hepatotoxicity, CH-FGF21 could alleviate ALI progression and promote the recovery of liver function. These findings demonstrated that a simple assembly of CH nanoparticles carrying FGF21 could be applied for the treatment of liver diseases.

The Progress of Chitosan-Based Nanoparticles for Intravesical Bladder Cancer Treatment

Bladder cancer (BC) is the most frequently occurring cancer of the urinary system, with non-muscle-invasive bladder cancer (NMIBC) accounting for 75-85% of all the bladder cancers. Patients with NMIBC have a good survival rate but are at high risk for tumor recurrence and disease progression. Intravesical instillation of antitumor agents is the standard treatment for NMIBC following transurethral resection of bladder tumors. Chemotherapeutic drugs are broadly employed for bladder cancer treatment, but have limited efficacy due to chemo-resistance and systemic toxicity. Additionally, the periodic voiding of bladder and low permeability of the bladder urothelium impair the retention of drugs, resulting in a weak antitumoral response. Chitosan is a non-toxic and biocompatible polymer which enables better penetration of specific drugs to the deeper cell layers of the bladder as a consequence of temporarily abolishing the barrier function of urothelium, thus offering multifaceted biomedical applications in urinary bladder epithelial. Nowadays, the rapid development of nanoparticles significantly improves the tumor therapy with enhanced drug transport. This review presents an overview on the state of chitosan-based nanoparticles in the field of intravesical bladder cancer treatment.

A Novel 3D Printing Particulate Manufacturing Technology for Encapsulation of Protein Therapeutics: Sprayed Multi Adsorbed-Droplet Reposing Technology (SMART)

Recently, various innovative technologies have been developed for the enhanced delivery of biologics as attractive formulation targets including polymeric micro and nanoparticles. Combined with personalized medicine, this area can offer a great opportunity for the improvement of therapeutics efficiency and the treatment outcome. Herein, a novel manufacturing method has been introduced to produce protein-loaded chitosan particles with controlled size. This method is based on an additive manufacturing technology that allows for the designing and production of personalized particulate based therapeutic formulations with a precise control over the shape, size, and potentially the geometry. Sprayed multi adsorbed-droplet reposing technology (SMART) consists of the high-pressure extrusion of an ink with a well determined composition using a pneumatic 3D bioprinting approach and flash freezing the extrudate at the printing bed, optionally followed by freeze drying. In the present study, we attempted to manufacture trypsin-loaded chitosan particles using SMART. The ink and products were thoroughly characterized by dynamic light scattering, rheometer, Scanning Electron Microscopy (SEM), and Fourier Transform Infra-Red (FTIR) and Circular Dichroism (CD) spectroscopy. These characterizations confirmed the shape morphology as well as the protein integrity over the process. Further, the effect of various factors on the production were investigated. Our results showed that the concentration of the carrier, chitosan, and the lyoprotectant concentration as well as the extrusion pressure have a significant effect on the particle size. According to CD spectra, SMART ensured Trypsin's secondary structure remained intact regardless of the ink composition and pressure. However, our study revealed that the presence of 5% (w/v) lyoprotectant is essential to maintain the trypsin's proteolytic activity. This study demonstrates, for the first time, the viability of SMART as a single-step efficient process to produce biologics-based stable formulations with a precise control over the particulate morphology which can further be expanded across numerous therapeutic modalities including vaccines and cell/gene therapies.

Effects of Charged Polyelectrolytes on Amyloid Fibril Formation of a Tau Fragment

The microtubule-associated protein tau is involved in more than 20 different neurological disorders characterized by aberrant intracellular aggregation of tau in the brain. Here, we investigated the aggregation of a novel 20-residue model peptide, tau298-317, which is derived from the key microtubule binding domain of the full sequence tau. Our results show that tau298-317 highly mimics the physical and aggregation properties of tau. Under normal physiological conditions, the peptide maintains a disordered random coil without aggregation. The presence of polyanionic heparin (Hep) significantly promotes the aggregation of this peptide to form amyloid fibrils. The Hep-induced aggregation is sensitive to the ionic strength of the solution and the introduction of the negatively charged phosphate group on a serine (Ser305) residue in the sequence, suggesting an important role of electrostatic interactions in the mechanism of Hep-mediated aggregation. In addition, two positively charged polysaccharides, chitosan (CHT) and its quaternary derivative N-trimethyl chitosan (TMC), were found to effectively inhibit Hep-induced aggregation of tau298-317 in a concentration-dependent manner. Attractive electrostatic interactions between the positively charged moieties in CHT/TMC and the negatively charged residues of Hep play a critical role in inhibiting Hep-peptide interactions and suppressing peptide aggregation. Our results suggest that positively charged polyelectrolytes with optimized charged groups and charge distribution patterns can serve as effective molecular candidates to block tau-Hep interactions and prevent aggregation of tau induced by Hep and other polyanions.

Nanochitosan: Commemorating the Metamorphosis of an ExoSkeletal Waste to a Versatile Nutraceutical

Chitin (poly-N-acetyl-D-glucosamine) is the second (after cellulose) most abundant organic polymer. In its deacetylated form-chitosan-becomes a very interesting material for medical use. The chitosan nano-structures whose preparation is described in this article shows unique biomedical value. The preparation of nanochitosan, as well as the most vital biomedical applications (antitumor, drug delivery and other medical uses), have been discussed in this review. The challenges confronting the progress of nanochitosan from benchtop to bedside clinical settings have been evaluated. The need for inclusion of nano aspects into chitosan research, with improvisation from nanotechnological inputs has been prescribed for breaking down the limitations. Future perspectives of nanochitosan and the challenges facing nanochitosan applications and the areas needing research focus have been highlighted.

Poly-ion complex (PIC) formation of heparin and polyamines: PIC with tetrakis (3-aminopropyl) ammonium allows sustained release of heparin

Physical mixtures of cationic polymers and heparin have been developed to overcome the limitations of unfractionated heparin. In this study, we found that heparin associates with natural polyamines in water, resulting in the generation of a poly-ion complex (PIC). PIC formation (or stability) was influenced by the concentration and ratio of heparin and polyamines, molecular weight of heparin, nature of polyamines, and pH conditions. Interestingly, the PIC obtained when heparin and tetrakis (3-aminopropyl) ammonium (Taa) were mixed exhibited stability and was sticky in nature. PIC formation was due to an electrostatic interaction between heparin and Taa. Heparin-Taa PIC was administered subcutaneously to mice, and the time to maximum heparin concentration within the therapeutic range of heparin was markedly increased compared to that after a single dose of heparin. These results suggest that the quaternary ammonium structure of Taa is critical for the preparation of a stable PIC, thereby allowing the sustained release of heparin into the blood.

Thrombolytic Agents: Nanocarriers in Controlled Release

Thrombosis is a life-threatening pathological condition in which blood clots form in blood vessels, obstructing or interfering with blood flow. Thrombolytic agents (TAs) are enzymes that can catalyze the conversion of plasminogen to plasmin to dissolve blood clots. The plasmin formed by TAs breaks down fibrin clots into soluble fibrin that finally dissolves thrombi. Several TAs have been developed to treat various thromboembolic diseases, such as pulmonary embolisms, acute myocardial infarction, deep vein thrombosis, and extensive coronary emboli. However, systemic TA administration can trigger non-specific activation that can increase the incidence of bleeding. Moreover, protein-based TAs are rapidly inactivated upon injection resulting in the need for large doses. To overcome these limitations, various types of nanocarriers have been introduced that enhance the pharmacokinetic effects by protecting the TA from the biological environment and targeting the release into coagulation. The nanocarriers show increasing half-life, reducing side effects, and improving overall TA efficacy. In this work, the recent advances in various types of TAs and nanocarriers are thoroughly reviewed. Various types of nanocarriers, including lipid-based, polymer-based, and metal-based nanoparticles are described, for the targeted delivery of TAs. This work also provides insights into issues related to the future of TA development and successful clinical translation.

Fabrication and Characterization of Polysaccharide Composite Films from Polyion Complex Particles

Biomaterials made of natural polysaccharides have attracted much attention due to the fact of their excellent properties, such as high biocompatibility and biodegradability, and their specific biological functions based on their chemical structures. This study demonstrates that polysaccharide composite films can be fabricated from polyion complexes (PICs) with their particles used as building components. Dispersion of PIC particles prepared by mixing, centrifugation, and re-dispersion of dilute solutions of cationic and anionic polysaccharides were cast, dried, and formed into films several micrometers thick. These films were homogenous and water insoluble. It was revealed that the component anionic polysaccharides affected the film’s properties such as the swelling behavior and mechanical characteristics. Adhesion of NIH3T3 cells (integrin: high, CD44: lack or weak) and A549 cells (integrin: high, CD44: high) to the composite films were examined. Both NIH3T3 and A549 cells adhered to heparin/chitosan (HEP/CHI) film because HEP has an affinity for integrin through fibronectin. However, A549 cells adhered to chondroitin sulfate (CS)/CHI and hyaluronic acid (HYA)/CHI films, whereas NIH3T3 cells did not, because both CS and HYA have affinity for CD44. These results indicated that the biological functions of anionic polysaccharides were maintained on the surface of the composite films. It was also possible to fabricate films composed of three kinds of polysaccharides: one cationic polysaccharide and two kinds of anionic polysaccharides. These results show that the properties of films composed of three kinds of polysaccharides may be controllable depending on the anionic polysaccharide composition rates.

Preparation of PEG-grafted chitosan/streptokinase nanoparticles to improve biological half-life and reduce immunogenicity of the enzyme

Streptokinase, as a thrombolytic drug, is widely used in treatment of cardiovascular disorders and deep vein thrombosis. Streptokinase is immunogenic due to its prokaryotic source, having short biological half-life (i.e. 15 to 30 min) that is not enough for an efficient therapy. In this study, nanoparticles (NPs) of chitosan/streptokinase and polyethylene glycol (PEG)-grafted chitosan/streptokinase were prepared by polyelectrolyte complex method. Particle size of chitosan and PEG-grafted chitosan NPs were 154 ± 42 and 211 ± 47 nm, respectively. Results showed that using PEG in preparation of nanoparticles leads to ~24% decrease in encapsulation efficiency. Encapsulation of streptokinase in the NPs also resulted in a slight reduction in enzymatic activity. However, in vivo findings indicated that response of the immune system was delayed for 20 days and blood circulation time of the enzyme increased up to 120 min by using PEG. Biological half-life of the drug also increased up to twice in PEG-grafted chitosan. In conclusion, PEG-grafted chitosan NPs could be an alternative for delivery of streptokinase to reduce its clinical limitations.

Review of polysaccharide particle-based functional drug delivery

This review investigates the significant role polysaccharide particles play in functional drug delivery. The importance of these systems is due to the wide variety of polysaccharides and their natural source meaning that they can provide biocompatible and biodegradable systems with a range of both biological and chemical functionality valuable for drug delivery. This functionality includes protection and presentation of working therapeutics through avoidance of the reticuloendothelial system, stabilization of biomacromolecules and increasing the bioavailability of incorporated small molecule drugs. Transport of the therapeutic is also key to the utility of polysaccharide particles, moving drugs from the site of administration through mucosal binding and transport and using chemistry, size and receptor mediated drug targeting to specific tissues. This review also scrutinizes the methods of synthesizing and constructing functional polysaccharide particle drug delivery systems that maintain and extend the functionality of the natural polysaccharides.

Polyelectrolyte-Based Platforms for the Delivery of Peptides and Proteins

The use of peptides and proteins in the pharmaceutical field has increased dramatically over recent years. They have been especially relevant to advances in the treatment of cancer, rheumatoid arthritis, leukemia, and cardiovascular, ophthalmological, metabolic, and infectious diseases. Despite the great potential of peptides and proteins, their use in pharmaceuticals has failed to reach its full potential because of some outstanding challenges. They are unstable under storage conditions and in biological milieus, and their high molecular weight limits permeation through biological membranes. A variety of delivery systems have been investigated to overcome these limitations. Polyelectrolytes (PEs) are molecules that bear multiple negative or positive charges. These molecules play an important role in various platforms relating to the delivery of peptide/protein-based drugs and subunit vaccines. The most commonly utilized PEs include chitosan, alginate, chondroitin sulfate, and poly(γ-glutamic acid). PE-based delivery systems, such as polyelectrolyte complexes (PECs), PE-coated nanocarriers, and PE multilayers, were designed to protect peptides and proteins from degradation and facilitate their absorption. These delivery systems are especially effective when administered orally or intranasally. This review emphasizes the important role of PEs and PE-based delivery vehicles in peptide/protein-based drugs and vaccines.

pH-Sensitive Chitosan-Heparin Nanoparticles for Effective Delivery of Genetic Drugs into Epithelial Cells

Chitosan has been extensively studied as a genetic drug delivery platform. However, its efficiency is limited by the strength of DNA and RNA binding. Expecting a reduced binding strength of cargo with chitosan, we proposed including heparin as a competing polyanion in the polyplexes. We developed chitosan–heparin nanoparticles by a one-step process for the local delivery of oligonucleotides. The size of the polyplexes was dependent on the mass ratio of polycation to polyanion. The mechanism of oligonucleotide release was pH-dependent and associated with polyplex swelling and collapse of the polysaccharide network. Inclusion of heparin enhanced the oligonucleotide release from the chitosan-based polyplexes. Furthermore, heparin reduced the toxicity of polyplexes in the cultured cells. The cell uptake of chitosan–heparin polyplexes was equal to that of chitosan polyplexes, but heparin increased the transfection efficiency of the polyplexes two-fold. The application of chitosan–heparin small interfering RNA (siRNA) targeted to vascular endothelial growth factor (VEGF) silencing of ARPE-19 cells was 25% higher. Overall, chitosan–heparin polyplexes showed a significant improvement of gene release inside the cells, transfection, and gene silencing efficiency in vitro, suggesting that this fundamental strategy can further improve the transfection efficiency with application of non-viral vectors.

Polyelectrolyte Complexes of Natural Polymers and Their Biomedical Applications

Polyelectrolyte complexes (PECs), composed of natural and biodegradable polymers, (such as positively charged chitosan or protamine and negatively charged glycosaminoglycans (GAGs)) have attracted attention as hydrogels, films, hydrocolloids, and nano-/micro-particles (N/MPs) for biomedical applications. This is due to their biocompatibility and biological activities. These PECs have been used as drug and cell delivery carriers, hemostats, wound dressings, tissue adhesives, and scaffolds for tissue engineering. In addition to their comprehensive review, this review describes our original studies and provides an overview of the characteristics of chitosan-based hydrogel, including photo-cross-linkable chitosan hydrogel and hydrocolloidal PECs, as well as molecular-weight heparin (LH)/positively charged protamine (P) N/MPs. These are generated by electrostatic interactions between negatively charged LH and positively charged P together with their potential biomedical applications.

Alphastatin-Loaded Chitosan Nanoparticle Preparation and Its Antiangiogenic Effect on Lung Carcinoma

Alphastatin is a 24-amino acid peptide and can suppress tumor angiogenesis by inhibiting both the migration and tubule formation of vascular endothelial cells. However, the anticancer effect of Alphastatin is limited due to the short half-life and degradation in the body. In this study, Alphastatin-loaded chitosan nanoparticles (AsCs NPs) were prepared with an initial concentration of 2 mg/ml for chitosan and 1 mg/ml for Alphastatin. AsCs NPs presented the encapsulation efficiency of 32.4%, the mean particle size of 387.4 nm, the polydispersity index of 0.223, and the zeta potential of +28.1 mV. AsCs NPs have a sustained release for 6 days and were stable in serum for at least 24 hours. And the NPs could preserve the integrity of encapsulated Alphastatin and released Alphastatin for 24 hours. In a subcutaneous LA975 lung carcinoma xenograft T739 mouse model, AsCs NPs significantly inhibited the tumor growth, tumor volume, and microvessel density (MVD), and the antitumor effect was even stronger than that of Alphastatin. In addition, the VEGF-induced tube formation of HUVEC could be inhibited by AsCs NPs in vitro and the serum containing AsCs NPs, and the protein level of SphK1 in HUVEC was also decreased by AsCs NPs, suggesting an inhibitory effect of AsCs NPs on the SphK1-S1P signaling pathway. Furthermore, hemolysis assay showed a safety on blood compatibility of AsCs NPs. Our study indicated that AsCs NPs inhibited the SphK1-S1P signaling pathway and enhanced the antiangiogenic effect of Alphastatin both in vitro and in vivo.

The preparation and morphology control of heparin-based pH sensitive polyion complexes and their application as drug carriers

Heparin as negative polysaccharide is a universal building block to form polyion complex with different cationic counterparts. In this paper, three different cations, including chitosan, benzyldodecyldimethyl ammonium bromide and doxorubicin hydrochloride, were used to prepare heparin-based polyion complexes (HPICs). Their morphologies could be tuned by heparin content in HPIC, and they also showed pH-sensitive decomposition. Doxorubicin was further encapsulated into micelle and vesicle carrier made from heparin-benzyldodecyl dimethyl ammonium bromide PIC, whereas heparin-doxorubicin PIC could be directly used as drug carrier. In vitro drug release proved the drug carriers exhibit obvious pH sensitive release behaviour. Cytotoxicity indicated the drug carrier possessed significant cytotoxicity to tumor cells. The cell uptake observed by CLSM showed the carrier was able to deliver antitumor drug into tumor cell's nucleus. Consequently, these results showed the promising potential of HPIC in drug carrier application.

Glycans in nanomedicine, impact and perspectives

Glycans have been selected by nature for both structural and 'recognition' purposes. Taking inspiration from nature, nanomedicine exploits glycans not only as structural constituents of nanoparticles and nanostructured biomaterials but also as selective interactors of such glyco-nanotools. Surface glycosylation of nanoparticles finds application in targeting specific cells, whereas recent findings give evidence that the glycan content of cell microenvironment is able to induce the cell fate. This review will highlight the role of glycans in nanomedicine, schematizing the different uses and roles in drug-delivery systems and in biomaterials for regenerative medicine.

Antimicrobial Activity from Colistin-Heparin Lamellar-Phase Complexes for the Coating of Biomedical Devices

Infections arising in hospitalized patients, particularly those who have undergone surgery and are reliant on receiving treatment through biomedical devices, continue to be a rising concern. It is well-known that aqueous mixtures of oppositely charged surfactant and polymer molecules can self-assemble to form liquid crystalline structures, primarily via electrostatically driven interactions that have demonstrated great potential as tailored-release nanomaterials. Colistin is a re-emerging antibiotic used against multidrug-resistant Gram-negative bacteria. Its amphiphilic structure allows it to form micellar aggregates in solution. Thus, the aim of this study was to determine whether structured complexes form between colistin and negatively charged biopolymers, such as the highly sulfated anticoagulant, heparin. Cross-polarized light microscopy and synchrotron small-angle X-ray scattering were employed to visualize the appearance of birefringent structures and identify liquid crystalline structures, respectively, formed across the interface between solutions of colistin and heparin. A lamellar phase with a lattice parameter of ∼40 Å was formed upon contact between the oppositely charged solutions of colistin and heparin. In addition, in vitro release studies showed a slow release of colistin from the lamellar-phase gel complexes into the bulk media, and disk diffusion bioassays revealed antimicrobial activity against Pseudomonas aeruginosa. This system provides a novel, cost-effective, and simple approach to reducing the risk of infections by potentially applying the formulation as a coating for biomedical implants or tubing.

Nanoparticles combined with growth factors: recent progress and applications

Increasing attention has been focused on the applications of nanoparticles combined with growth factors (NPs/GFs) due to the substantial functions of GFs in regenerative medicine and disease treatments.

In vitro cytotoxicity and in vivo efficacy of 5-fluorouracil-loaded enteric-coated PEG-cross-linked chitosan microspheres in colorectal cancer therapy in rats

PURPOSE

Microspheres of chitosan (CS) cross-linked with polyethylene glycol (PEG) were prepared by emulsion-cross-linking followed by the solvent evaporation technique. The formulations were characterized and subjected to in vitro and in vivo tests to assess cell growth, changes in cell morphology, and activities by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay on human HT-29 colon cancer cell-lines.

METHODS

In vivo activity was evaluated for dimethyl hydrazine-induced colorectal cancer in albino male Wistar rats. Biochemical and histological parameters were evaluated to understand their effectiveness for colon cancer therapy.

RESULTS

The 5-FU immediate release (IR) formulations suspended in SCMC produced an immediate cytotoxic effect, whereas microspheres inhibited proliferation of tumor cells to induce apoptosis over an extended time. Minimum inhibitory concentration (IC₅₀) values for both standard plain 5-FU and 5-FU-loaded microspheres were respectively 5.00 ± 0.004 µg/mL and 165 ± 1.9 µg/mL which showed the improved safety profile of the microsphere formulation. Tissue distribution showed high concentration of 5-FU in colon that was higher than IC₅₀ value required to stop the growth or death of colon cancer cells from the colonic dysplasia in Duke's stage A. Significant reduction in tumor volume and multiplicity was observed with increased levels of liver enzymes in animals when treated with standard 5-FU formulation compared with 5-FU loaded microspheres. Elevated levels of serum albumin, creatinine, leukocytopenia, and thrombocytopenia were observed in animals for the standard 5-FU formulation.

CONCLUSION

The PEG cross-linked CS microspheres of this study slowly released 5-FU up to 24 h to colonic region and enhanced the antitumor activity.

Novel protein-loaded chondroitin sulfate-N-[(2-hydroxy-3-trimethylammonium)propyl]chitosan nanoparticles with reverse zeta potential: preparation, characterization, and ex vivo assessment

A facile polyelectrolyte complexation method for the preparation of both positively and negatively surface charged nanoparticles composed of chondroitin sulfate (ChS) and N-[(2-hydroxy-3-trimethylammonium)propyl]chitosan (HTCC) is reported. Production of ChS-HTCC nanoparticles with reverse zeta potential was easily controlled by varying the ChS/HTCC mass ratio. The encapsulation efficiency increased with the increase in initial FITC-BSA concentration in positively charged NPs and reached 75%. However, a maximum of 20% encapsulation efficiency was achieved in the case of negatively charged NPs. In vitro release studies of positively charged ChS-HTCC NPs showed a small burst effect followed by a continued and controlled release. Both charges of ChS-HTCC NPs showed no cytotoxicity in HUVECs. The confocal images showed that ChS-HTCC NPs of both charges can be incorporated and retained by the A549 cells. Flow cytometric analysis data demonstrated that ChS-HTCC NPs of both charges were detected in more than 80% of the A549 cells.

Cytotoxicity of chitosan/streptokinase nanoparticles as a function of size: An artificial neural networks study

Predicting the size and toxicity of chitosan/streptokinase nanoparticles at various values of processing parameters was the aim of this study. For the first time, a comprehensive model could be developed to determine the cytotoxicity of the nanoparticles as a function of their size. Then, artificial neural networks were used for identifying main factors influencing self-assembly prepared nanoparticles size and cytotoxicity. Three variables included polymer concentration; pH and stirring time were used for a modeling study. A second modeling was performed to evaluate the influence of particles' size on toxicity. Experimentally data modeled using ANNs was validated against unseen data. The response surfaces generated from the software demonstrated that chitosan concentration is the dominant factor with a direct effect on size. Results also showed that the most important factor in determining the particles' toxicity is size--smaller particles showed more toxic effects, regardless of the effect of other input parameters. From the Clinical Editor: The understanding of toxicity of nanoparticles is of prime importance. In this article, the authors generated a model to visualize the relationship between nanoparticle size and its cellular toxicity, using chitosan/streptokinase nanoparticles. The data generated here would help the design of future nanoparticles of appropriate sizes for the application in the clinical setting.

In vitro cytotoxicity and in vivo efficacy of 5-fluorouracil-loaded enteric-coated PEG-crosslinked chitosan microspheres in colorectal cancer therapy in rats

PURPOSE

Microspheres of chitosan (CS) crosslinked with polyethylene glycol (PEG) were prepared by emulsion crosslinking followed by solvent evaporation technique. The formulations were characterized and subjected to in vitro and in vivo tests to assess cell growth, changes in cell morphology and activities by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay on human HT-29 colon cancer cell lines.

METHODS

In vivo activity was evaluated for dimethyl hydrazine-induced colorectal cancer in albino male Wistar rats. Biochemical and histological parameters were evaluated to understand their effectiveness for colon cancer therapy.

RESULTS

The 5-FU immediate release (IR) formulations suspended in sodium carboxymethyl cellulose (SCMC) produced an immediate cytotoxic effect, whereas microspheres inhibited the proliferation of tumor cells to induce apoptosis over an extended time. Minimum inhibitory concentration (IC50) values for both standard plain 5-FU and 5-FU-loaded microspheres were, respectively, 5.00 ± 0.004 µg/mL and 165 ± 1.9 µg/mL which showed the improved safety profile of the microsphere formulation. Tissue distribution showed high concentration of 5-FU in colon that was higher than IC50 required to stop the growth or death of colon cancer cells from the colonic dysplasia in Duke's Stage A. Significant reduction in tumor volume and multiplicity was observed with increased levels of liver enzymes in animals when treated with standard 5-FU formulation compared to 5-FU-loaded microspheres. Elevated levels of serum albumin, creatinine, leukocytopenia and thrombocytopenia were observed in animals for the standard 5-FU formulation.

CONCLUSION

The PEG-crosslinked CS microspheres of this study slowly released 5-FU up to 24 h to colonic region and enhanced the antitumor activity.

Self-assembling lipid modified glycol-split heparin nanoparticles suppress lipopolysaccharide-induced inflammation through TLR4-NF-κB signaling

Self-assembling heparin nanoparticles have attracted much attention as promising drug carriers for various drugs, genes and imaging agents. In the present investigation, we found that heparin nanoparticles are selective Toll-like receptor 4 (TLR-4) antagonists and have a much greater anti-inflammatory effect than native heparin. More specifically, we developed self-assembling nanoparticles composed of glycol-split heparin/D-erythro-sphingosine conjugates (NAHNP), characterized their physicochemical properties and anti-inflammatory effect in vitro. Unlike native heparin, NAHNP significantly inhibited lipopolysaccharide-induced activation of MyD88-dependent NF-κB signaling pathway and production of pro-inflammatory cytokines such as TNF-alpha from mouse macrophages with IC50 = 0.019 mg/mL. Furthermore, we investigated the structure-activity relationship of the conjugates and identified the length of attached alkyl chains of d-erythro-sphingosine to be critical for anti-inflammatory effect. Decrease in alkyl chain length of NAHNP resulted in loss of inhibitory activity. In line with these findings, 6-O-sulfate groups of D-glucosamine residue were essential for effective inhibition, while removal of 2-O-sulfo and 3-O-sulfo groups as well as replacement of N-sulfo groups with N-acetyl did not alter anti-inflammatory activity. Therefore, NAHNP would be a promising candidate in acute and chronic inflammatory disorders, in addition to the nature of a drug carrier.

Advances in preparation and characterization of chitosan nanoparticles for therapeutics

CONTEXT

Polymers have been largely explored for the preparation of nanoparticles due to ease of preparation and modification, large gene/drug loading capacity, and biocompatibility. Various methods have been adapted for the preparation and characterization of chitosan nanoparticles.

OBJECTIVE

Focus on the different methods of preparation and characterization of chitosan nanoparticles.

METHODS

Detailed literature survey has been done for the studies reporting various methods of preparation and characterization of chitosan nanoparticles.

RESULTS AND CONCLUSION

Published database suggests of several methods which have been developed for the preparation and characterization of chitosan nanoparticles as per the application.

Auto-associative heparin nanoassemblies: a biomimetic platform against the heparan sulfate-dependent viruses HSV-1, HSV-2, HPV-16 and RSV

A new, simple and green method was developed for the manufacturing of heparin nanoassemblies active against the heparan sulfate-dependent viruses HSV-1, HSV-2, HPV-16 and RSV. These nanoassemblies were obtained by the auto-association of O-palmitoyl-heparin and α-cyclodextrin in water. The synthesized O-palmitoyl-heparin derivatives mixed with α-cyclodextrin resulted in the formation of crystalline hexagonal nanoassemblies as observed by transmission electron microscopy. The nanoassembly mean hydrodynamic diameters were modulated from 340 to 659 nm depending on the type and the initial concentration of O-palmitoyl-heparin or α-cyclodextrin. The antiviral activity of the nanoassemblies was not affected by the concentration of the components. However, the method of the synthesis of O-palmitoyl-heparin affected the antiviral activity of the formulations. We showed that reduced antiviral activity is correlated with lower sulfation degree and anticoagulant activity.

Pullulan-based nanoparticles as carriers for transmucosal protein delivery

Polymeric nanoparticles have revealed very effective in transmucosal delivery of proteins. Polysaccharides are among the most used materials for the production of these carriers, owing to their structural flexibility and propensity to evidence biocompatibility and biodegradability. In parallel, there is a preference for the use of mild methods for their production, in order to prevent protein degradation, ensure lower costs and easier procedures that enable scaling up. In this work we propose the production of pullulan-based nanoparticles by a mild method of polyelectrolyte complexation. As pullulan is a neutral polysaccharide, sulfated and aminated derivatives of the polymer were synthesized to provide pullulan with a charge. These derivatives were then complexed with chitosan and carrageenan, respectively, to produce the nanocarriers. Positively charged nanoparticles of 180-270 nm were obtained, evidencing ability to associate bovine serum albumin, which was selected as model protein. In PBS pH 7.4, pullulan-based nanoparticles were found to have a burst release of 30% of the protein, which maintained up to 24h. Nanoparticle size and zeta potential were preserved upon freeze-drying in the presence of appropriate cryoprotectants. A factorial design was approached to assess the cytotoxicity of raw materials and nanoparticles by the metabolic test MTT. Nanoparticles demonstrated to not cause overt toxicity in a respiratory cell model (Calu-3). Pullulan has, thus, demonstrated to hold potential for the production of nanoparticles with an application in protein delivery.

Comparative studies on chitosan and polylactic-co-glycolic acid incorporated nanoparticles of low molecular weight heparin

This study was performed to test the feasibility of chitosan and polylactic-co-glycolic acid (PLGA) incorporated nanoparticles as sustained-release carriers for the delivery of negatively charged low molecular weight heparin (LMWH). Fourier transform infrared (FTIR) spectrometry was used to evaluate the interactions between chitosan and LMWH. The shifts, intensity, and broadening of the characteristic peaks for the functional groups in the FTIR spectra indicated that strong interactions occur between the positively charged chitosans and the negatively charged LMWHs. Three types of LMWH nanoparticles (NP-1, NP-2, and NP-3) were prepared using chitosan with or without PLGA: NP-1 nanoparticles were formed by polyelectrolyte complexation after single mixing, NP-2 nanoparticles were prepared by polyelectrolyte complexation after single emulsion-diffusion-evaporation, and NP-3 nanoparticles were optimized by double emulsion-diffusion-evaporation. NP-3 nanoparticles of LMWH prepared by the emulsion-diffusion-evaporation method showed significant differences in particle morphology, size, zeta potential, and drug release profile compared to NP-1 nanoparticles formed by polyelectrolyte complexation. Another ionic complex of LMWH with chitosan-incorporated PLGA nanoparticles (NP-2) showed lower drug entrapment efficiency than that of NP-1 and NP-3. The drug release rate of NP-3 was slower than the release rates of NP-1 and NP-2, although particle morphology of NP-3 was similar to that of NP-2. Cell viability was not adversely affected when cells were treated with all three types of nanoparticles. The data presented in this study demonstrate that nanoparticles formulated with chitosan-PLGA could be a safe sustained-release carrier for the delivery of LMWH.

Therapeutic angiogenesis: controlled delivery of angiogenic factors

Therapeutic angiogenesis aims at treating ischemic diseases by generating new blood vessels from existing vasculature. It relies on delivery of exogenous factors to stimulate neovasculature formation. Current strategies using genes, proteins and cells have demonstrated efficacy in animal models. However, clinical translation of any of the three approaches has proved to be challenging for various reasons. Administration of angiogenic factors is generally considered safe, according to accumulated trials, and offers off-the-shelf availability. However, many hurdles must be overcome before therapeutic angiogenesis can become a true human therapy. This article will highlight protein-based therapeutic angiogenesis, concisely review recent progress and examine critical challenges. We will discuss growth factors that have been widely utilized in promoting angiogenesis and compare their targets and functions. Lastly, since bolus injection of free proteins usually result in poor outcomes, we will focus on controlled release of proteins.