Polyion Complex Micelles Composed of All-TranS Retinoic Acid and Poly (Ethylene Glycol)-Grafted-Chitosan

All-trans Retinoic Acid-incorporated Glycol Chitosan Nanoparticles Regulate Macrophage Polarization in Pg-LPS-Induced Inflammation

OBJECTIVE

The occurrence and development of inflammation are closely correlated to the polarization of macrophages. All-trans retinoic acid (ATRA) has been proven to promote the polarization of macrophages from M1 to M2, but this lacks an effective carrier to participate in the biological response. The present study aims to determine whether retinoic acid-incorporated glycol chitosan (RA-GC) nanoparticles can regulate macrophage polarization in Porphyromonas gingivalis-lipopolysaccharide (Pg-LPS)-induced inflammation.

METHODS

Mouse 264.7 cell lines were treated with 1 µg/mL Pg-LPS to induce inflammation. After the effects of ATRA and RA-GC on the activity of macrophages were detected by CCK-8 assay, cells induced with Pg-LPS were assigned to the blank control group (GC) nanoparticles without ATRA, and experimental groups (GC nanoparticles loaded with different concentrations of ATRA: 1, 10 and 100 µg/mL). The effects of RA-GC on inflammatory cytokines tumor necrosis factor-α, interleukin (IL)-10 and IL-12 in macrophages were detected by enzyme-linked immunosorbent assay (ELISA). Subsequently, the effects of GC nanoparticles loaded with/without ATRA on macrophage polarization in an inflammatory environment were detected by RT-PCR and Western blotting.

RESULTS

The results revealed that RA-GC had no significant effect on macrophage activity. However, RA-GC could effectively inhibit the Pg-LPS-induced inflammatory factor expression in macrophages. Meanwhile, the experimental results confirmed that RA-GC could downregulate the expression of inducible nitric oxide synthase (iNOS) (a marker of M1 macrophages) and upregulate the expression of mannose receptor and Arginase-1 (a marker of M2 macrophages) in a dose-dependent manner.

CONCLUSION

The present study confirms that RA-GC can promote the M2 polarization of macrophages in an inflammatory environment, and proposes this as a promising target for the clinical treatment of Pg-LPS-related diseases.

Current Opportunities for Targeting Dysregulated Neurodevelopmental Signaling Pathways in Glioblastoma

Glioblastoma (GBM) is the most common and highly lethal type of brain tumor, with poor survival despite advances in understanding its complexity. After current standard therapeutic treatment, including tumor resection, radiotherapy and concomitant chemotherapy with temozolomide, the median overall survival of patients with this type of tumor is less than 15 months. Thus, there is an urgent need for new insights into GBM molecular characteristics and progress in targeted therapy in order to improve clinical outcomes. The literature data revealed that a number of different signaling pathways are dysregulated in GBM. In this review, we intended to summarize and discuss current literature data and therapeutic modalities focused on targeting dysregulated signaling pathways in GBM. A better understanding of opportunities for targeting signaling pathways that influences malignant behavior of GBM cells might open the way for the development of novel GBM-targeted therapies.

Potential Role of Growth Factors Controlled Release in Achieving Enhanced Neuronal Trans-differentiation from Mesenchymal Stem Cells for Neural Tissue Repair and Regeneration

With an increase in the incidence of neurodegenerative diseases, a need to replace incapable conventional methods has arisen. To overcome this burden, stem cells therapy has emerged as an efficient treatment option. Endeavours to accomplish this have paved the path to neural regeneration through efficient neuronal transdifferentiation. Despite their potential, the use of stem cells still entails several limitations, such as low differentiation efficiency and difficulties in guiding differentiation. The process of neural differentiation through the stem cells is achieved through the use of chemical inducers or growth factors and their direct introduction reduces their bioavailability in the system. To address these limitations, neural regeneration ventures require growth factors to be effectively implemented on stem cells in order to produce functional neuronal precursor cells. An efficient technique to achieve it is through the delivery of growth factors via microcarriers for their sustained release. It ensures the presence of commensurable concentration even at later stages of neuronal transdifferentiation. Nanofibers and nanoparticles, along with liposomes and such, have been used to implement this. The interaction between such carriers and the growth factors is mainly electrostatic. Such interaction enables them to form a stable assembly through immobilisation of the growth factor either onto their surfaces or within the core of their structures. The rate of sustained release depends upon the release kinetics associated with the polymeric structure employed and its interaction with the encapsulated growth factor. The sustained release ensures that the stem cells immerse under the effect of the growth factors for a prolonged period, ultimately aiding in the formation of cells showing ample characteristics of neuron precursors. This review analyses the various carriers that have been employed for the release of growth factors in an orderly fashion and their constituents, along with the advantages and the limitations they pose in delivering the growth factors for facilitating the process of neuronal transdifferentiation.

Advances and challenges in retinoid delivery systems in regenerative and therapeutic medicine

Retinoids regulate a wide spectrum of cellular functions from the embryo throughout adulthood, including cell differentiation, metabolic regulation, and inflammation. These traits make retinoids very attractive molecules for medical purposes. In light of some of the physicochemical limitations of retinoids, the development of drug delivery systems offers several advantages for clinical translation of retinoid-based therapies, including improved solubilization, prolonged circulation, reduced toxicity, sustained release, and improved efficacy. In this Review, we discuss advances in preclinical and clinical tests regarding retinoid formulations, specifically the ones based in natural retinoids, evaluated in the context of regenerative medicine, brain, cancer, skin, and immune diseases. Advantages and limitations of retinoid formulations, as well as prospects to push the field forward, will be presented.

Chitosan-Based Non-viral Gene and Drug Delivery Systems for Brain Cancer

Central nervous system (CNS) tumors are a leading source of morbidity and mortality worldwide. Today, different strategies have been developed to allow targeted and controlled drug delivery into the brain. Gene therapy is a system based on the modification of patient's cells through the introduction of genetic material to exert a specific action. Administration of the foreign genetic material can be done through viral-mediated delivery or non-viral delivery via physical or mechanical systems. For brain cancer specifically, gene therapy can overcome the actual challenge of blood brain barrier penetration, the main reason for therapeutic failure. Chitosan (CS), a natural based biodegradable polymer obtained from the exoskeleton of crustaceans such as crab, shrimp, and lobster, has been used as a delivery vehicle in several non-viral modification strategies. This cationic polysaccharide is highly suitable for gene delivery mainly due to its chemical properties, its non-toxic nature, its capacity to protect nucleic acids through the formation of complexes with the genetic material, and its ease of degradation in organic environments. Recent evidence supports the use of CS as an alternative gene delivery system for cancer treatment. This review will describe multiple studies highlighting the advantages and challenges of CS-based delivery structures for the treatment of brain tumors. Furthermore, this review will provide insight on the translational potential of various CS based-strategies in current clinical cancer studies. Specifically, CS-based nanostructures including nanocapsules, nanospheres, solid-gel formulations, and nanoemulsions, also microshperes and micelles will be evaluated.

Self-assembled amphiphilic core-shell nanocarriers in line with the modern strategies for brain delivery

Disorders of the central nervous system (CNS) represent increasing social and economic problems all over the world which makes the effective transport of drugs to the brain a crucial need. In the last decade, many strategies were introduced to deliver drugs to the brain trying to overcome the challenge of the blood brain barrier (BBB) using both invasive and non-invasive methods. Non-invasive strategy represented in the application of nanocarriers became very common. One of the most hopeful nanoscopic carriers for brain delivery is core-shell nanocarriers or polymeric micelles (PMs). They are more advantageous than other nanocarriers. They offer small size, ease of preparation, ease of sterilization and the possibility of surface modification with various ligands. Hence, the aim of this review is to discuss modern strategies for brain delivery, micelles as a successful delivery system for the brain and how micelles could be modified to act as "magic bullets" for brain delivery.

In vitro and in vivo evaluation of docetaxel-loaded stearic acid-modified Bletilla striata polysaccharide copolymer micelles

Bletilla striata polysaccharides (BSPs) have been used in pharmaceutical and biomedical industry, the aim of the present study was to explore a BSPs amphiphilic derivative to overcome its application limit as poorly water-soluble drug carriers due to water-soluble polymers. Stearic acid (SA) was selected as a hydrophobic block to modify B. striata polysaccharides (SA-BSPs). Docetaxel (DTX)-loaded SA-BSPs (DTX-SA-BSPs) copolymer micelles were prepared and characterized. The DTX release percentage in vitro and DTX concentration in vivo was carried out by using high performance liquid chromatography. HepG2 and HeLa cells were subjected to MTT (3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyl tetrazonium bromide) assay to evaluate the cell viability. In vitro evaluation of copolymer micelles showed higher drug encapsulation and loading capacity. The release percentage of DTX from DTX-SA-BSPs copolymer micelles and docetaxel injection was 66.93 ± 1.79% and 97.06 ± 1.56% in 2 days, respectively. The DTX-SA-BSPs copolymer micelles exhibited a sustained release of DTX. A 50% increase in growth inhibition was observed for HepG2 cells treated with DTX-SA-BSPs copolymer micelles as compared to those treated with docetaxel injection for 72 h. DTX-SA-BSPs copolymer micelles presented a similar growth inhibition effect on Hela cells. Furthermore, absolute bioavailability of DTX-SA-BSPs copolymer micelles was shown to be 1.39-fold higher than that of docetaxel injection. Therefore, SA-BSPs copolymer micelles may be used as potential biocompatible polymers for cancer chemotherapy.

Docetaxel-Loaded Self-Assembly Stearic Acid-Modified Bletilla striata Polysaccharide Micelles and Their Anticancer Effect: Preparation, Characterization, Cellular Uptake and In Vitro Evaluation

Poorly soluble drugs have low bioavailability after oral administration, thereby hindering effective drug delivery. A novel drug-delivery system of docetaxel (DTX)-based stearic acid (SA)-modified Bletilla striata polysaccharides (BSPs) copolymers was successfully developed. Particle size, zeta potential, encapsulation efficiency (EE), and loading capacity (LC) were determined. The DTX release percentage in vitro was determined using high performance liquid chromatography (HPLC). The hemolysis and in vitro anticancer activity were studied. Cellular uptake and apoptotic rate were measured using flow cytometry assay. Particle size, zeta potential, EE and LC were 125.30 ± 1.89 nm, -26.92 ± 0.18 mV, 86.6% ± 0.17%, and 14.8% ± 0.13%, respectively. The anticancer activities of DTX-SA-BSPs copolymer micelles against HepG2, HeLa, SW480, and MCF-7 (83.7% ± 1.0%, 54.5% ± 4.2%, 48.5% ± 4.2%, and 59.8% ± 1.4%, respectively) were superior to that of docetaxel injection (39.2% ± 1.1%, 44.5% ± 5.3%, 38.5% ± 5.4%, and 49.8% ± 2.9%, respectively) at 0.5 μg/mL drug concentration. The DTX release percentage of DTX-SA-BSPs copolymer micelles and docetaxel injection were 66.93% ± 1.79% and 97.06% ± 1.56% in two days, respectively. Cellular uptake of DTX-FITC-SA-BSPs copolymer micelles in cells had a time-dependent relation. Apoptotic rate of DTX-SA-BSPs copolymer micelles and docetaxel injection were 73.48% and 69.64%, respectively. The SA-BSPs copolymer showed good hemocompatibility. Therefore, SA-BSPs copolymer can be used as a carrier for delivering hydrophobic drugs.

Carbohydrate-based amphiphilic nano delivery systems for cancer therapy

Nanoparticles (NPs) are novel drug delivery systems that have been attracting more and more attention in recent years, and have been used for the treatment of cancer, infection, inflammation and other diseases. Among the numerous classes of materials employed for constructing NPs, organic polymers are outstanding due to the flexibility of design and synthesis and the ease of modification and functionalization. In particular, NP based amphiphilic polymers make a great contribution to the delivery of poorly-water soluble drugs. For example, natural, biocompatible and biodegradable products like polysaccharides are widely used as building blocks for the preparation of such drug delivery vehicles. This review will detail carbohydrate based amphiphilic polymeric systems for cancer therapy. Specifically, it focuses on the nature of the polymer employed for the preparation of targeted nanocarriers, the synthetic methods, as well as strategies for the application and evaluation of biological activity. Applications of the amphiphilic polymer systems include drug delivery, gene delivery, photosensitizer delivery, diagnostic imaging and specific ligand-assisted cellular uptake. As a result, a thorough understanding of the relationship between chemical structure and biological properties facilitate the optimal design and rational clinical application of the resulting carbohydrate based nano delivery systems for cancer therapy.

Retinoic acid‑incorporated glycol chitosan nanoparticles inhibit the expression of Ezh2 in U118 and U138 human glioma cells

At present, one of the most life threatening types of adult brain tumor is glioblastoma multiforme (GBM). The molecular mechanism underlying the progression of GBM remains to be fully elucidated. The modern method of clinical treatment has only improved the average survival rates of a newly diagnosed patients with GBM by ~15 months. Therefore, the discovery of novel molecules, which are involved in glioma inhibition is required. In the present study, U118 and U138 human glioma cells were transfected with all-trans retinoic acid (RA)-incorporated glycol chitosan (GC) nanoparticles. An MTT assay was used for the analysis of cell proliferation and flow cytometric analysis and ssDNA detection assays were performed for the determination of induction of cell apoptosis. Cell cycle distribution was analyzed by flow cytometry. Exposure of the U118 and U138 human glioma cells to the RA-incorporated GC nanoparticles for 24 h resulted in a concentration-dependent inhibition of cell proliferation. Among the range of experimental RA concentrations, the minimum effective treatment concentration was 10 µM, with a half maximal inhibitory concentration of 25 µM. The results also demonstrated that RA transfection resulted in the inhibition of cell proliferation, inhibition of the expression of Ezh2, and apoptosis through the mitochondrial signaling pathway by a decrease in membrane potential, the release of cytochrome c, and cell cycle arrest in the G₀/G₁ phase.

Self-assembled nanoparticles of glycyrrhetic acid-modified pullulan as a novel carrier of curcumin

Glycyrrhetic acid (GA)-modified pullulan nanoparticles (GAP NPs) were synthesized as a novel carrier of curcumin (CUR) with a degree of substitution (DS) of GA moieties within the range of 1.2-6.2 groups per hundred glucose units. In the present study, we investigated the physicochemical characteristics, release behavior, in vitro cytotoxicity and cellular uptake of the particles. Self-assembled GAP NPs with spherical shapes could readily improve the water solubility and stability of CUR. The CUR release was sustained and pH-dependent. The cellular uptake of CUR-GAP NPs was confirmed by green fluorescence in the cells. An MTT study showed CUR-GAP NPs with higher cytotoxicity in HepG2 cells than free CUR, but GAP NPs had no significant cytotoxicity. GAP is thus an excellent carrier for the solubilization, stabilization, and controlled delivery of CUR.

The amine content of PEGylated chitosan Bombyx mori nanoparticles acts as a trigger for protein delivery

In modern medicine, effective protein therapy is a major challenge to which a significant contribution can be expected from nanoscience through the development of novel delivery systems. Here we present the effect of the amine content of nanoparticles based on PEGylated chitosan Bombyx mori (PEG-O-ChsBm) copolymers on the entrapment of molecules in a search for highly efficient nanocarriers. PEG-O-ChsBm copolymers were synthesized with amine contents from 1.12% to 0.70%, and nanoparticles were generated by self-assembly in dilute aqueous solutions. These nanoparticles successfully entrapped molecules with a wide range of sizes, the efficiency of which was dependent on their amine contents. While hydrophobic molecules were entrapped with high efficiency in all types of nanoparticle, hydrophilic molecules were entrapped only in those with low amine content. Bovine serum albumin, selected as a model protein, was entrapped in nanoparticles and efficiently released in acidic conditions. The triggered entrapment of molecules in PEG-O-ChsBm nanoparticles by selection of the appropriate amine content represents a straightforward way to modulate their delivery by fine changes in the properties of nanocarriers.

All-trans retinoic acid-incorporated nanoparticles of deoxycholic acid-conjugated dextran for treatment of CT26 colorectal carcinoma cells

PURPOSE

All-trans retinoic acid (RA)-incorporated nanoparticles were prepared using deoxycholic acid-conjugated dextran (DexDA). Anticancer activity of RA-incorporated DexDA nanoparticles were tested in vitro and in vivo.

METHODS

RA-incorporated nanoparticles were prepared by dialysis. Antiproliferative and anti-invasive potential of RA-incorporated nanoparticles were studied using CT26 colorectal carcinoma cells.

RESULTS

RA-incorporated nanoparticles have small particle sizes of around 70-300 nm and spherical shapes. The higher drug-feeding ratio and higher substitution degree of deoxycholic acid in the conjugates resulted in higher drug contents, lower loading efficiency, and larger particle size. RA release rate became slower at higher drug contents and higher substitution degree of deoxycholic acid in the DexDA conjugates. The antiproliferation activity, anti-invasive activity, and matrix metalloproteinase 2 expression of RA-incorporated nanoparticles against CT26 cells in vitro was similar to RA. However, RA-incorporated nanoparticles had superior antimetastatic activity in an animal pulmonary metastatic model of CT26 cells compared to RA itself.

CONCLUSION

RA-incorporated nanoparticles showed similar anticancer activity in vitro and superior antimetastatic activity in vivo in a pulmonary metastatic model of CT26 cells. We suggest that RA-incorporated nanoparticles are promising vehicles for efficient delivery of RA.

Effect of pullulan nanoparticle surface charges on HSA complexation and drug release behavior of HSA-bound nanoparticles

Nanoparticle (NP) compositions such as hydrophobicity and surface charge are vital to determine the presence and amount of human serum albumin (HSA) binding. The HSA binding influences drug release, biocompatibility, biodistribution, and intercellular trafficking of nanoparticles (NPs). Here, we prepared 2 kinds of nanomaterials to investigate HSA binding and evaluated drug release of HSA-bound NPs. Polysaccharides (pullulan) carboxyethylated to provide ionic derivatives were then conjugated to cholesterol groups to obtain cholesterol-modified carboxyethyl pullulan (CHCP). Cholesterol-modified pullulan (CHP) conjugate was synthesized with a similar degree of substitution of cholesterol moiety to CHCP. CHCP formed self-aggregated NPs in aqueous solution with a spherical structure and zeta potential of -19.9 ± 0.23 mV, in contrast to -1.21 ± 0.12 mV of CHP NPs. NPs could quench albumin fluorescence intensity with maximum emission intensity gradually decreasing up to a plateau at 9 to 12 h. Binding constants were 1.12 × 10(5) M(-1) and 0.70 × 10(5) M(-1) to CHP and CHCP, respectively, as determined by Stern-Volmer analysis. The complexation between HSA and NPs was a gradual process driven by hydrophobic force and inhibited by NP surface charge and shell-core structure. HSA conformation was altered by NPs with reduction of α-helical content, depending on interaction time and particle surface charges. These NPs could represent a sustained release carrier for mitoxantrone in vitro, and the bound HSA assisted in enhancing sustained drug release.

Permanent hair dye-incorporated hyaluronic acid nanoparticles

We prepared p-phenylenediamine (PDA)-incorporated nanoparticles using hyaluronic acid (HA). PDA-incorporated HA nanoparticles have spherical shapes and sizes were less than 300 nm. The results of FT-IR spectra indicated that PDA-incorporated HA nanoparticles were formed by ion-complex formation between amine group of PDA and carboxyl group of HA. Furthermore, powder-X-ray diffractogram (XRD) measurement showed that intrinsic crystalline peak of PDA disappeared by formation of nanoparticle with HA at XRD measurement. These results indicated that PDA-incorporated HA nanoparticles were formed by ion-complex formation. At drug release study, the higher PDA contents induced faster release rate from nanoparticles. PDA-incorporated nanoparticles showed reduced intrinsic toxicity against HaCaT human keratinocyte cells at MTT assay and apoptosis assay. We suggest that PDA-incorporated HA nanoparticles are promising candidates for novel permanent hair dye.

Hair dye-incorporated poly-γ-glutamic acid/glycol chitosan nanoparticles based on ion-complex formation

Background

p-Phenylenediamine (PDA) or its related chemicals are used more extensively than oxidative hair dyes. However, permanent hair dyes such as PDA are known to have potent contact allergy reactions in humans, and severe allergic reactions are problematic.

Methods

PDA-incorporated nanoparticles were prepared based on ion-complex formation between the cationic groups of PDA and the anionic groups of poly(γ-glutamic acid) (PGA). To reinforce PDA/PGA ion complexes, glycol chitosan (GC) was added. PDA-incorporated nanoparticles were characterized using field-emission scanning electron microscopy, Fourier- transform infrared (FT-IR) spectroscopy, dynamic light scattering, and powder X-ray diffractometry (XRD).

Results

Nanoparticles were formed by ion-complex formation between the amine groups of PDA and the carboxyl groups of PGA. PDA-incorporated nanoparticles are small in size (<100 nm), and morphological observations showed spherical shapes. FT-IR spectra results showed that the carboxylic acid peak of PGA decreased with increasing PDA content, indicating that the ion complexes were formed between the carboxyl groups of PGA and the amine groups of PDA. Furthermore, the intrinsic peak of the carboxyl groups of PGA was also decreased by the addition of GC. Intrinsic crystalline peaks of PDA were observed by XRD. This crystalline peak of PDA was completely nonexistent when nanoparticles were formed by ion complex between PDA, PGA, and GC, indicating that PDA was complexed with PGA and no free drug existed in the formulation. During the drug-release experiment, an initial burst release of PDA was observed, and then PDA was continuously released over 1 week. Cytotoxicity testing against HaCaT human skin keratinocyte cells showed PDA-incorporated nanoparticles had lower toxicity than PDA itself. Furthermore, PDA-incorporated nanoparticles showed reduced apoptosis and necrosis reaction at HaCaT cells.

Conclusion

The authors suggest that these microparticles are ideal candidates for a vehicle for decreasing side effects of hair dye.

Anti-tumor activity of all-trans retinoic acid-incorporated glycol chitosan nanoparticles against HuCC-T1 human cholangiocarcinoma cells

The aim of this study is to investigate antitumor activity of all-trans retinoic acid (RA)-incorporated glycol chitosan (GC) nanoparticles. RA-incorporated GC nanoparticles were prepared by electrostatic interaction between RA and amine group of GC. RA-incorporated GC nanoparticles have spherical shape and their particle size was 317 ± 34.5 nm. They were simply reconstituted into aqueous solution without changes of intrinsic properties. RA-incorporated GC nanoparticles were evidently inhibited the proliferation of HuCC-T1 cholangiocarcinoma cells at higher than 20 μg/ml of RA concentration while empty GC vegicles did not affect to the viablity of tumor cells. Apoptosis and necrosis analysis of tumor cells with treatment of RA or RA-incorporated GC nanoparticles also supported these results. Invasion test using Matrigel also showed that invasion of tumor cells was significantly inhibited at higher than 20 μg/ml of RA concentration. Wound healing assay also showed that RA-incorporated GC nanoparticles were inhibited migration of tumor cells as similar to RA itself. Our results suggested that RA-incorporated GC nanoparticles is a promising vehicles for RA delivery to HuCC-T1 cholangiocarcinoma cells.

Preparation of polylactide-co-glycolide nanoparticles incorporating celecoxib and their antitumor activity against brain tumor cells

Background

Celecoxib, a cyclo-oxygenase (COX)-2 inhibitor, has been reported to mediate growth inhibitory effects and to induce apoptosis in various cancer cell lines. In this study, we examined the potential effects of celecoxib on glioma cell proliferation, migration, and inhibition of COX-2 expression in vitro.

Methods

Celecoxib was incorporated into poly DL-lactide-co-glycolide (PLGA) nanoparticles for antitumor drug delivery.

Results

PLGA nanoparticles incorporating celecoxib had spherical shapes and their particle sizes were in the range of 50–200 nm. Drug-loading efficiency was not significantly changed according to the solvent used, except for acetone. Celecoxib was released from the PLGA nanoparticles for more than 2 days, and the higher the drug content, the longer the duration of drug release. PLGA nanoparticles incorporating celecoxib showed cytotoxicity against U87MG tumor cells similar to that of celecoxib administered alone. Furthermore, celecoxib did not affect the degree of migration of U87MG cells. PLGA nanoparticles incorporating celecoxib showed dose-dependent cytotoxicity similar to that of celecoxib alone in C6 rat glioma cells. Western blot assay of the C6 cells showed that neither celecoxib alone nor PLGA nanoparticles incorporating celecoxib affected COX-2 expression.

Conclusion

PLGA nanoparticles incorporating celecoxib had antitumor activity similar to that of celecoxib alone, even though these particles did not affect the degree of migration or COX-2 expression in the tumor cells.

Influence of histidine on the release of all-trans retinoic acid from self-assembled glycol chitosan nanoparticles

OBJECTIVE

In this study, the influence of N-acetyl histidine (NAHis) on the all-trans retinoic acid (ATRA) release from the NAHis-conjugated self-assembled glycol chitosan (GC) nanoparticles was investigated.

METHODS

NAHis was conjugated to GC as a hydrophobic moiety to prepare the self-assembled nanoparticles, and ATRA was incorporated into the inner core of the NAHis-GC nanoparticles. The ATRA release from NAHis-GC nanoparticles was performed at 37 degrees C in a phosphate-buffered saline buffer (pH 5.5 or 7.4) for 48 hours.

RESULTS

At a pH of 5.5, less than 20% (w/w) of total loading amount of ATRA was released from the nanoparticles after 48 hours. In contrast, two times greater amount of ATRA was released at a pH of 7.4. The ATRA release rate from the NAHis-GC nanoparticles was significantly slower at a pH of 5.5 than at a pH of 7.4.

CONCLUSION

The release profiles of ATRA that was incorporated into the NAHis-GC nanoparticles were controlled by the NAHis content in the GC nanoparticles.

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.

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.

Self-aggregated nanoparticles from methoxy poly(ethylene glycol)-modified chitosan: Synthesis; characterization; aggregation and methotrexate release in vitro

Methoxy poly(ethylene glycol)-grafted-chitosan (mPEG-g-CS) conjugates were synthesized by formaldehyde linking method and characterized by Fourier transform infrared (FT-IR) and proton nuclear magnetic resonance ((1)H-NMR). The degree of substitution (DS) of methoxy poly (ethylene glycol) (mPEG) in the mPEG-g-CS molecules determined by (1)H-NMR ranged from 19% to 42%. The critical aggregation concentration (CAC) was determined by fluorescence spectroscopy using pyrene as fluorescence probe and its value was 0.07 mg/mL in water. mPEG-g-CS formed monodisperse self-aggregated nanoparticles with a roughly spherical shape and a mean diameter of 261.9 nm were prepared by the dialysis method. mPEG-g-CS self-aggregated nanoparticles were used as carriers of poorly water-soluble anticancer drug methotrexate (MTX). MTX was physically entrapped inside mPEG-g-CS self-aggregated nanoparticles by dialysis method and the characteristics of MTX-loaded mPEG-g-CS self-aggregated nanoparticles were analyzed using dynamic laser light scattering (DLLS), transmission electron microscopy (TEM). Moreover, in vitro release behavior of MTX was also investigated and the results showed that MTX was continuously released more than 50% in 48 h.

Enhancement of hydrophilic drug loading and release characteristics through micellization with new carboxymethyldextran-PEG block copolymers of tunable charge density

The micellization of a model cationic drug, diminazene diaceturate (DIM) and a series of new diblock copolymers, carboxymethyldextran-poly(ethylene glycols) (CMD-PEG), were evaluated as a function of the ionic charge density or degree of substitution (DS) of the carboxymethyldextran block and the molar ratio, [+]/[-], of positive charges provided by the drug to negative charges provided by CMD-PEG. Micelles ([+]/[-]=2) incorporated up to 64% (w/w) DIM and ranged in hydrodynamic radius (R(H)) from 36 to 50 nm, depending on the molecular weight and DS of CMD-PEG. The critical association concentration (CAC) was on the order of 15-50mg/L for CMD-PEG of DS>60%, and ca. 100mg/L for CMD-PEG of DS approximately 30%. The micelles were stable upon storage in solution for up to 2 months and after freeze-drying in the presence of trehalose. They remained intact within the 4<pH<11 range and for solutions of pH 5.3, they resisted increases in salinity up to approximately 0.4M NaCl in the case of CMD-PEG of high DS. However, micelles of DIM and a CMD-PEG of low DS (30%) disintegrated in solutions containing more than 0.1M NaCl, setting a minimum value to the DS of copolymers useful in in vivo applications. Sustained in vitro DIM release was observed for micelles of CMD-PEG of high DS ([+]/[-]=2).

Use of nanoparticles for drug delivery in glioblastoma multiforme

Treatment of glioblastoma multiforme (GBM), a primary malignant tumor of the brain, is one of the most challenging problems as no currently available treatment is curative. Surgery remains the basic treatment in which the bulk of the tumor is removed and the peripheral infiltrating part is the target of supplementary treatments. The currently available anticancer therapeutics have less than optimal usefulness for GBM, mainly owing to delivery problems to the tumor, including those due to blood-brain barrier. Several new therapies in development for GBM will require innovative methods of delivery besides the current practice of direct introduction of drugs and devices into the tumor. Nanobiotechnology, particularly nanoparticles, is making a significant contribution to the improvement of drug delivery in cancer and many of these technologies can be applied to GBM. Nanobiotechnology can provide a platform for combination of diagnostics, therapeutics, and its delivery to the tumor with subsequent monitoring of response. These technologies are reviewed and the prospects of improvement of therapeutic delivery to the brain are excellent during the next 5 years. Curing of GBM, however, depends on discovery of an anticancer agent that will destroy GBM completely.

The use of chitosan as a flocculant in mammalian cell culture dramatically improves clarification throughput without adversely impacting monoclonal antibody recovery

Flocculants have been employed for many years as aides in the clarification of wastewater, chemicals and food. Flocculants aggregate and agglutinate fine particles resulting in their settling from the liquid phase and a reduction in solution turbidity. These materials have not been widely used in the clarification of mammalian cell culture harvest. In this paper we examined chitosan as a flocculent of cells and cell particulates in NS0 culture harvest and the subsequent further clarification of this material by continuous flow centrifugation followed by depth and absolute filtration. Chitosan is an ideal flocculant for biotechnology applications as it is produced from non-mammalian sources (typically arthropod shells) and is also available in a highly purified form that is low in heavy metals, volatile organics and microbial materials. Chitosan is a polymer of deacetylated chitin. The deacetylation imparts limited solubility on insoluble chitin and the amino groups on the polymer result in a polycationic material at acidic and neutral pH that can interact with polyanions, such as DNA and cell culture debris (typically negatively charged). Likely the interaction of chitosan with cell culture particulate forms a germinal center for further interaction and agglomeration of particulates thereby reducing the solubility of these materials resulting in their settling out into the solid phase. Chitosan improved the clarification throughput six to seven folds without a deleterious effect on monoclonal antibody recovery or purity. The procedure for utilizing chitosan is facile, easily implemented, and highly effective in improving material clarity and increasing material throughput.