Hydrophobically Modified Glycol Chitosan Research Articles

Glycol chitosan-based tacrolimus-loaded nanomicelle therapy ameliorates lupus nephritis

BackgroundRecently, we developed hydrophobically modified glycol chitosan (HGC) nanomicelles loaded with tacrolimus (TAC) (HGC-TAC) for the targeted renal delivery of TAC. Herein, we determined whether the administration of the HGC-TAC nanomicelles decreases kidney injury in a model of lupus nephritis. Lupus-prone female MRL/lpr mice were randomly assigned into three groups that received intravenous administration of either vehicle control, an equivalent dose of TAC, or HGC-TAC (0.5 mg/kg TAC) weekly for 8 weeks. Age-matched MRL/MpJ mice without Faslpr mutation were also treated with HGC vehicle and used as healthy controls.ResultsWeekly intravenous treatment with HGC-TAC significantly reduced genetically attributable lupus activity in lupus nephritis-positive mice. In addition, HGC-TAC treatment mitigated renal dysfunction, proteinuria, and histological injury, including glomerular proliferative lesions and tubulointerstitial infiltration. Furthermore, HGC-TAC treatment reduced renal inflammation and inflammatory gene expression and ameliorated increased apoptosis and glomerular fibrosis. Moreover, HGC-TAC administration regulated renal injury via the TGF-β1/MAPK/NF-κB signaling pathway. These renoprotective effects of HGC-TAC treatment were more potent in lupus mice compared to those of TAC treatment alone.ConclusionOur study indicates that weekly treatment with the HGC-TAC nanomicelles reduces kidney injury resulting from lupus nephritis by preventing inflammation, fibrosis, and apoptosis. This advantage of a new therapeutic modality using kidney-targeted HGC-TAC nanocarriers may improve drug adherence and provide treatment efficacy in lupus nephritis mice.

Kidney-accumulating olmesartan-loaded nanomicelles ameliorate the organ damage in a murine model of Alport syndrome

ACE inhibitors or angiotensin II receptor blockers (ACEi/ARBs) have been a cornerstone of the management in kidney disease, but their use is often limited by undesired systemic effects, such as symptomatic hypotension. To minimize the extra-renal effects of ACEi/ARBs, we formulated hydrophobically modified glycol chitosan (HGC) nanomicelles releasing olmesartan (HGC-Olm) that specifically accumulated in the kidney, and investigated whether kidney-specific delivery of olmesartan by HGC nanomicelles could ameliorate organ damage in Col4a3−/− mouse, a murine model of progressive chronic kidney disease mimicking human Alport syndrome. Ex vivo tracing demonstrated that intravenously injected HGC-Olm nanomicelles were specifically delivered to the kidney, with sustained release of olmesartan for more than 48 h. Contrary to the conventional delivery of olmesartan via oral route, injection of HGC-Olm nanomicelles did not alter blood pressure in Col4a3−/− mice. Immunohistochemistry revealed that HGC nanomicelles were diffusely distributed from the cortex and glomeruli to the outer medulla, sparing the inner medulla. Phenotypic analysis showed that the attenuation of kidney fibrosis in the kidney of Col4a3−/− mice by HGC-Olm nanomicelles was comparable to that noted with conventionally delivered olmesartan. Therefore, our results suggest that HGC-Olm nanomicelles could be a safe and effective alternative drug delivery system for kidney diseases.

Design, characterization, and intracellular trafficking of biofunctionalized chitosan nanomicelles.

The hydrophobically modified glycol chitosan (HGC) nanomicelle has received increasing attention as a promising platform for the delivery of chemotherapeutic drugs. To improve the tumor selectivity of HGC, here an avidin and biotin functionalization strategy was applied. The hydrodynamic diameter of the biotin-avidin-functionalized HGC (cy5.5-HGC-B4F) was observed to be 104.7 nm, and the surface charge was +3.1 mV. Confocal and structured illumination microscopy showed that at 0.1 mg/ml, cy5.5-HGC-B4F nanomicelles were distributed throughout the cytoplasm of MDA-MB-231 breast cancer cells after 2 h of exposure without significant cytotoxicity. To better understand the intracellular fate of the nanomicelles, entrapment studies were performed and demonstrated that some cy5.5-HGC-B4F nanomicelles were capable of escaping endocytic vesicles, likely via the proton sponge effect. Quantitative analysis of the movements of endosomes in living cells revealed that the addition of HGC greatly enhanced the motility of endosomal compartments, and the nanomicelles were transported by early and late endosomes from cell periphery to the perinuclear region. Our results validate the importance of using live-cell imaging to quantitatively assess the dynamics and mechanisms underlying the complex endocytic pathways of nanosized drug carriers.

Glycol chitosan-based renal docking biopolymeric nanomicelles for site-specific delivery of the immunosuppressant

In this study, we propose the use of glycol chitosan for the targeted delivery of hydrophobic drugs such as tacrolimus (TAC) towards the kidney. We synthesized a hydrophobically modified glycol chitosan (HGC) polymeric nanomicelle followed by loading TAC resulting in TAC loaded HGC nanomicelles (HGC-TAC). The HGC-TAC nanomicelles displayed spherical morphology with superior drug loading content and encapsulation efficiency. in vitro and in vivo evaluations demonstrated that HGC-TAC nanomicelles are non toxic and delivered TAC preferentially to kidney while lowering the plasma concentrations. The therapeutic effects of HGC-TAC and unencapsulated (“bare”) TAC on the kidneys showed that a single intravenous administration of HGC-TAC achieved a therapeutic efficacy comparable to that obtained from daily intraperitoneal injections of TAC for 14 days without any systemic side effects. Thus, HGC-TAC nanomicelles could be effectively used for delivery of TAC towards the kidney, highlighting its potential as a safe modality for renal-targeted delivery of therapeutics.

Oral Soft Tissue Regeneration Using Nano Controlled System Inducing Sequential Release of Trichloroacetic Acid and Epidermal Growth Factor.

The effect of nano controlled sequential release of trichloroacetic acid (TCA) and epidermal growth factor (EGF) on the oral soft tissue regeneration was determined. Hydrophobically modified glycol chitosan (HGC) nano controlled system was developed for the sequential release of TCA and EGF, and the release pattern was identified. The HGC-based nano controlled release system was injected into the critical-sized defects created in beagles' palatal soft tissues. The palatal impression and its scanned body was obtained on various time points post-injection, and the volumetric amount of soft tissue regeneration was compared among the three groups: CON (natural regeneration control group), EXP1 (TCA-loaded nano controlled release system group), EXP2 (TCA and EGF individually loaded nano controlled release system). DNA microarray analysis was performed and various soft tissue regeneration parameters in histopathological specimens were measured. TCA release was highest at Day 1 whereas EGF release was highest at Day 2 and remained high until Day 3. In the volumetric measurements of impression body scans, no significant difference in soft tissue regeneration between the three groups was shown in two-way ANOVA. However, in the one-way ANOVA at Day 14, EXP2 showed a significant increase in soft tissue regeneration compared to CON. High correlation was determined between the histopathological results of each group. DNA microarray showed up-regulation of various genes and related cell signaling pathways in EXP2 compared to CON. HGC-based nano controlled release system for sequential release of TCA and EGF can promote regeneration of oral soft tissue defects.

Folate-conjugated hydrophobicity modified glycol chitosan nanoparticles for targeted delivery of methotrexate in rheumatoid arthritis.

Targeted delivery to the Rheumatoid arthritis (RA) which is characterized by destruction and degeneration of bones due to chronic inflammation is of great need. RA being a chronic autoimmune disorder might result in severe disability and morbidity. A targeted delivery system is designed to deliver methotrexate (MTX) for RA. Here, we synthesized folic acid (FA) conjugated hydrophobically modified glycol chitosan (GC) self-assembled nanoparticles (FA-GC-SA) for the targeted delivery of MTX to RA. The FA conjugation and hydrophobic modification of GC by stearic acid (SA) was confirmed by Fourier-transform infrared spectroscopy (FTIR). The FA-GC-SA was exploited for developing targeted nanoparticles encapsulating MTX by the ionic gelation method. The particles were characterized and evaluated for their targeting potential in in vitro cell culture studies. Further their in vivo efficacy in arthritis induced rats using collagen was also evaluated. FTIR confirms the successful modification of GC-SA and FA-GC-SA. The FA-GC-SA-MTX of size 153 ± 9 nm were prepared with high encapsulation efficiency of MTX. The FA-GC-SA-MTX size was further confirmed by transmission electron microscopy (TEM). In vitro cell studies revealed the superior efficacy of FA-GC-SA-MTX in cell cytotoxicity. Also, significantly higher cellular uptake of FA functionalized FA-GC-SA-MTX was observed in comparison to non-functionalized GC-SA-MTX attributed to folate receptors (FRs) mediated endocytosis. In vivo results confirms the potential of FA-GC-SA-MTX which reduces reduces the pro-inflammatory cytokines, paw thickness, and arthritis score in collagen induced rats. The results shows that FRs targeted FA-GC-SA-MTX has superior efficacy in the treatment of RA.

MHI-148 Cyanine Dye Conjugated Chitosan Nanomicelle with NIR Light-Trigger Release Property as Cancer Targeting Theranostic Agent.

Paclitaxel (PTX) loaded hydrophobically modified glycol chitosan (HGC) micelle is biocompatible in nature, but it requires cancer targeting ability and stimuli release property for better efficiency. To improve tumor retention and drug release characteristic of HGC-PTX nanomicelles, we conjugated cancer targeting heptamethine dye, MHI-148, which acts as an optical imaging agent, targeting moiety and also trigger on-demand drug release on application of NIR 808nm laser. The amine group of glycol chitosan modified with hydrophobic 5β-cholanic acid and the carboxyl group of MHI-148 were bonded by 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide/N-hydroxysuccinimide chemistry. Paclitaxel was loaded to MHI-HGC nanomicelle by an oil-in-water emulsion method, thereby forming MHI-HGC-PTX. Comparison of near infrared (NIR) dyes, MHI-148, and Flamma-774 conjugated to HGC showed higher accumulation for MHI-HGC in 4T1 tumor and 4T1 tumor spheroid. In vitro studies showed high accumulation of MHI-HGC-PTX in 4T1 and SCC7 cancer cell lines compared to NIH3T3 cell line. In vivo fluorescence imaging of the 4T1 and SCC7 tumor showed peak accumulation of MHI-HGC-PTX at day 1 and elimination from the body at day 6. MHI-HGC-PTX showed good photothermal heating ability (50.3°C), even at a low concentration of 33μg/ml in 1W/cm2 808nm laser at 1min time point. Tumor reduction studies in BALB/c nude mice with SCC7 tumor showed marked reduction in MHI-HGC-PTX in the PTT group combined with photothermal therapy compared to MHI-HGC-PTX in the group without PTT. MHI-HGC-PTX is a cancer theranostic agent with cancer targeting and optical imaging capability. Our studies also showed that it has cancer targeting property independent of tumor type and tumor reduction property by combined photothermal and chemotherapeutic effects.

Preparation and evaluation of exenatide loaded PLGA nanocapsules for oral administration

Hydrophobically modified glycol chitosan (HGC) nanoparticles loaded with mono-lithocholic acid-conjugated exendin-4 at the Lys27 residue (LAM1-Ex4) were prepared and characterized by particle size measurement, proteolytic stability, in vitro drug-release profile, and in vivo antidiabetic effects in a db/db diabetic mouse model. Compared with Ex-4-loaded HGC nanoparticles (Ex4/HGC NPs) prepared as a control, LAM1-Ex4-loaded HGC nanoparticles (LAM1-Ex4/HGC NPs) showed improved drug-loading efficiency, small particle size, enhanced resistance against proteolytic digestion, and an extended in vitro drug release profile. These findings may be attributable to the strong hydrophobic interaction between LAM1-Ex4 and the inner core of HGC. Furthermore, LAM1-Ex4/HGC NPs showed prolonged hypoglycemic efficacy in db/db mice, lasting 1 week after a single subcutaneous administration. The present study demonstrated that LAM1-Ex4/HGC NPs have considerable potential as a long-acting sustained-release antidiabetic system for type 2 diabetes.

Biocompatible and target specific hydrophobically modified glycol chitosan nanoparticles.

Cardiovascular disease is the leading cause of death in the United States. Atherosclerosis is a major cause for cardiovascular diseases. Drugs that treat atherosclerosis usually act nonspecifically. To enhance drug delivery specificity, the authors developed a hydrophobically modified glycol chitosan (HGC) nanoparticle that can specifically target activated endothelial cells. The biocompatibility of these nanoparticles toward red blood cells and platelets was evaluated through hemolysis, platelet activation, platelet thrombogenicity, and platelet aggregation assays. The biocompatibility of these nanoparticles toward vascular endothelial cells was evaluated by their effects on endothelial cell growth, metabolic activity, and activation. The results demonstrated that HGC nanoparticles did not cause hemolysis, or affect platelet activation, thrombogenicity, and aggregation capability in vitro. The nanoparticles did not impair vascular endothelial cell growth or metabolic activities in vitro, and did not cause cell activation either. When conjugated with intercellular adhesion molecular 1 antibodies, HGC nanoparticles showed a significantly increased targeting specificity toward activated endothelial cells. These results suggested that HGC nanoparticles are likely compatible toward red blood cells, platelets, and endothelial cells, and they can be potentially used to identify activated endothelial cells at atherosclerotic lesion areas within the vasculature, and deliver therapeutic drugs.

Mono-lithocholated exendin-4-loaded glycol chitosan nanoparticles with prolonged antidiabetic effects

Hydrophobically modified glycol chitosan (HGC) nanoparticles loaded with mono-lithocholic acid-conjugated exendin-4 at the Lys27 residue (LAM1-Ex4) were prepared and characterized by particle size measurement, proteolytic stability, in vitro drug-release profile, and in vivo antidiabetic effects in a db/db diabetic mouse model. Compared with Ex-4-loaded HGC nanoparticles (Ex4/HGC NPs) prepared as a control, LAM1-Ex4-loaded HGC nanoparticles (LAM1-Ex4/HGC NPs) showed improved drug-loading efficiency, small particle size, enhanced resistance against proteolytic digestion, and an extended in vitro drug release profile. These findings may be attributable to the strong hydrophobic interaction between LAM1-Ex4 and the inner core of HGC. Furthermore, LAM1-Ex4/HGC NPs showed prolonged hypoglycemic efficacy in db/db mice, lasting 1 week after a single subcutaneous administration. The present study demonstrated that LAM1-Ex4/HGC NPs have considerable potential as a long-acting sustained-release antidiabetic system for type 2 diabetes.

Distribution and accumulation of Cy5.5-labeled hydrophobically modified glycol chitosan in mice

The ultimate goal of this study is to assess the accumulation and distribution of hydrophobically modified glycol chitosan (HGC) as a degradable nanoparticle in the body. To understand the movement of degradable nanoparticle HGC in the body, we intravenously injected a dose of 20 mg/kg of Cy5.5-labeled HGC with size ranging from 320 to 400 nm into ICR mice, and measured the amount of fluorescence remaining in blood and several organs at various time intervals. In blood, the level of Cy5.5-labeled HGC increased at 15 min and after 30 min and then decreased gradually and reached a plateau at 28 days. In the tissue we confirmed the presence of nanoparticles at high levels in the order of kidney>liver>submandibular gland until 28 days after injection. However, we did not find the distribution of the particles into brain or testes. These results will provide basic information on HGC as a drug delivery agent.

Distribution and bioaccumulation of Lu177-labeled hydrophobically modified glycol chitosan in ICR mice

This study was conducted to evaluate the accumulation and distribution of HGC (hydrophobically modified glycol chitosan) as a degradable nanoparticle in the body. To determine the movement of degradable HGC nanoparticles in the body, 20 mg/kg of lutetium-labeled HGC (Lu-HGC) with a size range from 320 to 400 nm was injected intravenously into ICR mice, and the amount of radioactivity remaining in blood and several organs was measured at various time points a period of 5 days. In the pharmacokinetics analysis using the Lu radioisotope, the free Lu was mainly distributed and accumulated in the order of kidney>liver>lung at 1 day after the injection of radioisotope. However, the Lu-HGC showed a high distribution of nanoparticles in the order of liver>spleen>kidney until 5 days. These results would provide a basic pharmacokinetics for the use of HGC as a drug carrier in drug delivery system.

Facilitated intracellular delivery of peptide-guided nanoparticles in tumor tissues

Macromolecular nanoparticles can extravasate and accumulate within tumor tissues via the passive targeting system, reflecting enhanced permeability and the retention effect. However, the unsatisfactory tumor therapeutic efficacy of the passive-targeting system, attributable to the retention of extravasated nanoparticles in the vicinity of tumor vessels, argues that a new system that facilitates intracellular delivery of nanoparticles within tumors is needed. Here, we developed hydrophobically modified glycol chitosan (HGC) nanoparticles conjugated with interleukin-4 receptor (IL-4R) binding peptides, termed I4R, and tested them in mice bearing IL-4R-positive tumors. These HGC-I4R nanoparticles exhibited enhanced IL-4R-dependent cellular uptake in tumors compared to nonconjugated nanoparticles, leading to better therapeutic and imaging efficacy. We conclude that I4R facilitates and enhances cellular uptake of nanoparticles in tumor tissues. This study suggests that the intracelluar uptake of nanoparticles in tumors is an essential factor to consider in designing nanoparticles for tumor-targeted drug delivery and imaging.

Chitosan nanoparticles show rapid extrapulmonary tissue distribution and excretion with mild pulmonary inflammation to mice

Pulmonary delivery of nanoparticles (NP) conjugated with therapeutic agents has been considered recently for both lung disorders and systemic circulation. Hydrophobically modified glycol chitosan (HGC) NP have previously shown excellent deposition to the tumor site and non-destructive intracellular release. Here, we evaluated the kinetics and toxicity of HGC NP by intratracheal instillation to mice. HGC NP showed a positive charge and average hydrodynamic size was around 350 nm. The half-life of NP in the lung was determined as 131.97 ± 50.51 h. NP showed rapid uptake into systemic circulation and excretion via urine which was peaked at 6 h after instillation. Although HGC NP were distributed to several extrapulmonary organs, the levels were extremely low and transient. HGC NP induced transient neutrophilic pulmonary inflammation from 6 h to day 3 after instillation. Expression of pro-inflammatory cytokines (IL-1β, IL-6, and TNF-α) and chemokine (MIP-1α) in lung showed an increase from 1 h to 24 h after instillation and recovered thereafter. Our findings suggest that HGC NP can be successful candidates for use as pulmonary delivery vehicles, owing to their excellent biocompatibility, transiency, and low pulmonary toxicity, and property of rapid elimination without accumulation.

Cellular uptake pathway and drug release characteristics of drug‐encapsulated glycol chitosan nanoparticles in live cells

Herein, we evaluated the cellular uptake pathways of hydrophobically modified glycol chitosan (HGC) nanoparticles as nano-sized drug carriers using cellular imaging technology. The endocytic pathway of nanocarriers for intracellular drug delivery is of great interest for the design of high efficacy delivery carriers for therapeutic agents. To evaluate the cellular uptake pathways of HGC nanoparticles, HGC was chemically labeled with near infrared (NIR) fluorescence dye, Cy5.5, to visualize the nanoparticle under confocal laser scanning microscopy. The internalization pathways of HGC nanoparticles were evaluated after treatment of specific endocytosis inhibitors. Importantly, HCG nanoparticles showed different cellular uptake efficiency and intracellular fate in cytoplasm according to the internalization pathways. Furthermore, drug distribution also evaluated according to the endocytic pathways after treatment of drug encapsulated HGC nanoparticles. As a model drug, fluorescent photosensitizer, Ce6, was encapsulated into HGC (Ce6-HGC) nanoparticles and the distribution of Ce6 in cytoplasm was evaluated using confocal laser scanning microscopy. The intracellular drug distribution showed different manner through specific endocytic pathways. The cellular imaging technology is highly useful for evaluation of endocytosis pathways and intracellular fate of drug delivery carrier which are closely related to drug distribution and therapeutic efficacy.

Cellular uptake mechanism and intracellular fate of hydrophobically modified glycol chitosan nanoparticles

Polymeric nanoparticle-based carriers are promising agents for the targeted delivery of therapeutics to the intracellular site of action. To optimize the efficacy in delivery, often the tuning of physicochemical properties (i.e., particle size, shape, surface charge, lipophilicity, etc.) is necessary, in a manner specific to each type of nanoparticle. Recent studies showed an efficient tumor targeting by hydrophobically modified glycol chitosan (HGC) nanoparticles through the enhanced permeability and retention (EPR) effect. As a continued effort, here the investigations on the cellular uptake mechanism and the intracellular fate of the HGC nanoparticles are reported. The HGC nanoparticle, prepared by a partial derivatization of the free amino groups of glycol chitosan (GC) with 5β-cholanic acid, had a globular shape with the average diameter of 359 nm and the zeta potential of ca. 22 mV. Interestingly, these nanoparticles showed an enhanced distribution in the whole cells, compared to the parent hydrophilic GC polymers. In vitro experiments with endocytic inhibitors suggested that several distinct uptake pathways (e.g., clathrin-mediated endocytosis, caveolae-mediated endocytosis, and macropinocytosis) are involved in the internalization of HGC. Some HGC nanoparticles were found entrapped in the lysosomes upon entry, as determined by TEM and colocalization studies. Given such favorable properties including low toxicity, biocompatibility, and fast uptake by several nondestructive endocytic pathways, our HGC nanoparticles may serve as a versatile carrier for the intracellular delivery of therapeutic agents.

Prolonged antidiabetic effect of zinc-crystallized insulin loaded glycol chitosan nanoparticles in type 1 diabetic rats

New basal insulin formulation was designed and their structural characteristics were investigated in vitro and biological activities in type 1 diabetic rats. Zinc-crystallized insulin was physically loaded into hydrophobically modified glycol chitosan (HGC) nanoparticles by a dialysis method. The series of insulin-HGC formulations were prepared with different feed weight ratio of insulin to HGC from 0.5:1 to 4:1. The loading contents of insulin and size distribution of insulin-HGCs were characterized, and blood glucose responses were investigated in streptozotocin-induced diabetic rats after single subcutaneous injection of regular insulin and insulin-HGCs. The highest loading efficiency and content were obtained in insulin-HGC when a 1:1 feed weight ratio of insulin to HGC was employed. The hydrodynamic diameter of insulin-HGC nanoparticles were in the range of 200 to 500 nm with narrow size distribution. Insulin-HGC effectively sustained insulin release up to 40% within 12 hours followed by a slower controlled release. Insulin-HGC showed an extended blood glucose lowering effect up to 24 h and provided normal blood glucose levels after oral glucose (1.5 g/kg) load at 24 hours post-injection while regular insulin showed severe hypoglycemia. The prolonged time action profiles and low variability of insulin-HGC formulation resulted in improved blood glucose control in diabetic rats and fulfilled a pattern desirable of a basal insulin.

A new atherosclerotic lesion probe based on hydrophobically modified chitosan nanoparticles functionalized by the atherosclerotic plaque targeted peptides

We developed a new imaging probe for atherosclerotic lesion imaging by chemically conjugating an atherosclerotic plaque-homing peptide (termed the AP peptide) to hydrophobically modified glycol chitosan (HGC) nanoparticles. The AP peptide was previously discovered by using an in vivo phage display screening method. HGC nanoparticles were labeled with the near-infrared (NIR) fluorophore Cy5.5, yielding nanoparticles 314 nm in diameter. The binding characteristics of nanoparticles to cytokine (TNF-α)-activated bovine aortic endothelial cells (BAECs) were studied in vitro under static conditions and in a dynamic flow environment. AP-tagged HGC-Cy5.5 nanoparticles (100 µg/ml, 2 h incubation) bound more avidly to TNF-α-activated BAECs than to unactivated BAECs. Nanoparticles were mostly located in the membranes of BAECs, although some were taken up by the cells and were visible in the cytoplasm, suggesting that the AP peptides in HGC nanoparticles retained target selectivity for activated BAECs. Binding selectivity of AP-tagged HGC-Cy5.5 nanoparticles was also studied in vivo. NIR fluorescence imaging demonstrated that AP-tagged HGC-Cy5.5 nanoparticles bound better to atherosclerotic lesions in a low-density lipoprotein receptor-deficient ( Ldlr -/- ) atherosclerotic mouse than to such lesions in a normal mouse. These results suggest that the newly designed AP-tagged HGC-Cy5.5 nanoparticles may be useful for atherosclerotic lesion imaging, and may also be employed to elucidate pathophysiological changes, at the molecular level, on atherosclerotic endothelium.

Tumor targetability and antitumor effect of docetaxel-loaded hydrophobically modified glycol chitosan nanoparticles

Hydrophobically modified glycol chitosan (HGC) nanoparticles, a new nano-sized drug carrier, were prepared by introducing a hydrophobic molecule, cholanic acid, to water soluble glycol chitosan. The HGC nanoparticles were easily loaded with the anticancer drug docetaxel (DTX) using a dialysis method, and the resulting docetaxel-loaded HGC (DTX-HGC) nanoparticles formed spontaneously self-assembled aggregates with a mean diameter of 350 nm in aqueous condition. The DTX-HGC nanoparticles were well dispersed and stable for 2 weeks under physiological conditions (pH 7.4 and 37°C) and a sustained drug release profile, in vitro. In addition, the DTX-HGC nanoparticles were reasonably stable in the presence of excess bovine serum albumin, which suggested that the DTX-HGC nanoparticles might also be stable in the blood stream. The DTX-HGC nanoparticles exhibited a distinctive deformability in aqueous conditions, in that they could easily pass through a filter membrane with 200 nm pores despite their mean diameter of 350 nm. We also evaluated the time-dependent excretion profile, in vivo biodistribution, prolonged circulation time, and tumor targeting ability of DTX-HGC nanoparticles by using a non-invasive live animal imaging technology. Finally, under optimal conditions for cancer therapy, the DTX-HGC nanoparticles showed higher antitumor efficacy such as reduced tumor volume and increased survival rate in A549 lung cancer cells-bearing mice and strongly reduced the anticancer drug toxicity compared to that of free DTX in tumor-bearing mice. Together our results showed that the anticancer loaded nano-sized drug carriers are a promising nano-sized drug formulation for cancer therapy.

Hydrophobically modified glycol chitosan nanoparticles-encapsulated camptothecin enhance the drug stability and tumor targeting in cancer therapy

To prepare a water-insoluble camptothecin (CPT) delivery carrier, hydrophobically modified glycol chitosan (HGC) nanoparticles were constructed by chemical conjugation of hydrophobic 5β-cholanic acid moieties to the hydrophilic glycol chitosan backbone. Insoluble anticancer drug, CPT, was easily encapsulated into HGC nanoparticles by a dialysis method and the drug loading efficiency was above 80%. CPT-encapsulated HGC (CPT-HGC) nanoparticles formed nano-sized self-aggregates in aqueous media (280–330 nm in diameter) and showed sustained release of CPT for 1 week. Also, HGC nanoparticles effectively protected the active lactone ring of CPT from the hydrolysis under physiological condition, due to the encapsulation of CPT into the hydrophobic cores in the HGC nanoparticles. The CPT-HGC nanoparticles exhibited significant antitumor effects and high tumor targeting ability towards MDA-MB231 human breast cancer xenografts subcutaneously implanted in nude mice. Tumor growth was significantly inhibited after i.v. injection of CPT-HGC nanoparticles at doses of 10 mg/kg and 30 mg/kg, compared to free CPT at dose of 30 mg/kg. The significant antitumor efficacy of CPT-HGC nanoparticles was attributed to the ability of the nanoparticles to show both prolonged blood circulation and high accumulation in tumors, as confirmed by near infrared (NIR) fluorescence imaging systems. Thus, the delivery of CPT to tumor tissues at a high concentration, with the assistance of HGC nanoparticles, exerted a potent therapeutic effect. These results reveal the promising potential of HGC nanoparticles-encapsulated CPT as a stable and effective drug delivery system in cancer therapy.