Self-assembled hydrogel nanoparticles from curdlan derivatives: characterization, anti-cancer drug release and interaction with a hepatoma cell line (HepG2)

In vivo evaluation of an anticancer drug delivery system based on heparinized mesoporous silica nanoparticles

MSNs-HP loaded with only a low amount of a drug (DOX0.3) achieve a similar antitumor efficacy to that of large doses of the drug (DOX2.0, 7-fold higher in dosage than DOX0.3).

Preparation of novel curdlan nanoparticles for intracellular siRNA delivery

RNA interference (RNAi) down-regulates gene expression post-transcriptionally, which is a therapeutically significant phenomenon that could potentially reduce the level of disease related proteins that are undruggable by conventional small molecular approaches. However, clinical application of small interference RNAs (siRNAs) requires design of potent siRNA sequences and development of safe and efficient delivery systems. To create a biocompatible siRNA delivery agent, we chemically modified natural polysaccharide curdlan in a regioselective manner to introduce amino group in the glucose units. The resulting 6-amino-curdlan (6AC) is water soluble and forms nanoparticles upon complexing with siRNAs. The novel curdlan-based nanoparticles efficiently delivered siRNAs to human cancer cells and mouse primary cells, and reduced 70-90% of target mRNA level. Moreover, 6AC nanoparticles delivered siRNA targeting eGFP to mouse embryonic stem (mES) cells stably expressing eGFP, and produced substantial reductions of GFP protein level. The novel curdlan-based nanoparticle is a promising vehicle for delivery of short RNAs to knock down endogenous mRNAs.

The RNA expression signature of the HepG2 cell line as determined by the integrated analysis of miRNA and mRNA expression profiles

Understanding miRNAs' regulatory networks and target genes could facilitate the development of therapies for human diseases such as cancer. Although much useful gene expression profiling data for tumor cell lines is available, microarray data for miRNAs and mRNAs in the human HepG2 cell line have only been compared with that of other cell lines separately. The relationship between miRNAs and mRNAs in integrated expression profiles for HepG2 cells is still unknown. To explore the miRNA-mRNA correlations in hepatocellular carcinoma (HCC) cells, we performed miRNA and mRNA expression profiling in HepG2 cells and normal liver HL-7702 cells at the genome scale using next-generation sequencing technology. We identified 193 miRNAs that are differentially expressed in these two cell lines. Of these, 89 miRNAs were down-regulated in HepG2 cells compared with HL-7702 cells, while 104 miRNAs were up-regulated. We also observed 3035 mRNAs that are significantly dys-regulated in HepG2 cells. We then performed an integrated analysis of the expression data for differentially expressed miRNAs and mRNAs and found several miRNA-mRNA pairs that are significantly correlated in HepG2 cells. Further analysis suggested that these differentially expressed genes were enriched in four tumorigenesis-related signaling pathways, namely, ErbB, JAK-STAT, mTOR, and WNT, which until now had not been fully reported. Our results could be helpful in understanding the mechanisms of HCC occurrence and development.

Synthesis and characterization of folate-targeted dextran/retinoic acid micelles for doxorubicin delivery in acute leukemia

Folate and retinoic acid grafted/dextran (FA-RA/DEX) copolymers with different molecular weight of DEX were synthesized using carbonyldiimidazole and dimethylaminopyridine for targeted delivery of doxorubicin (DOX) in acute myelogenous leukemia (AML). The copolymers structure was confirmed by ¹H NMR and FTIR. Critical micelle concentration (CMC) of each copolymer was determined using pyrene as a fluorescent probe. DOX was loaded in micelles by the direct dissolution method. Physical properties of micelles, including particle size, zeta potential, drug loading efficiency, and drug release profiles, were examined. The orientation of the folate ligand on the surface of the micelles was studied by X-ray photoelectron spectroscopy (XPS) technique. The cytotoxicity of micelles loaded with DOX at different concentrations was studied in KG1 cells using MTT assay and their cellular uptake by flow cytometry technique. FTIR and ¹H NMR spectra confirmed successful production of the targeted micelles and XPS spectra showed the surface orientation of folate. R₁₅D₁₀F₇ copolymer produced micelles with particle size of 82.86 nm, polydispersity index of 0.3, zeta potential of −4.68 mV, drug loading efficiency of 96%, and release efficiency of 63%. DOX loaded in folate-targeted micelles of RA/DEX was more toxic than that in nontargeted micelles and free drug and seems promising in reducing drug resistance in AML.

Bio-responsive chitin-poly(L-lactic acid) composite nanogels for liver cancer

Hepatic carcinoma (HCC) is one of the most common cancer and its treatment has been considered a therapeutic challenge. Doxorubicin (Dox) is one of the most important chemotherapeutic agents used in the treatment for liver cancer. However, the efficacy of Dox therapy is restricted by the dose-dependent toxic side effects. To overcome the cardiotoxicity of Dox as well as the current problems of conventional modality treatment of HCC, we developed a locally injectable, biodegradable, and pH sensitive composite nanogels for site specific delivery. Both control and Dox loaded composite nanogel systems were analyzed by DLS, SEM, FTIR and TG/DTA. The size ranges of the control composite nanogels and their drug loaded counterparts were found to be 90±20 and 270±20 nm, respectively. The control chitin-PLA CNGs and Dox-chitin-PLA CNGs showed higher swelling and degradation in acidic pH. Drug entrapment efficiency and in vitro drug release studies were carried out and showed a higher drug release at acidic pH compared to neutral pH. Cellular internalization of the nanogel systems was confirmed by fluorescent microscopy. The cytotoxicity of the composite nanogels was analyzed toward HepG2 (human liver cancer) cell lines. Furthermore, the results of in vitro hemolytic assay and coagulation assay substantiate the blood compatibility of the system. Overall Dox-chitin-PLA CNGs system could be a promising anticancer drug delivery system for liver cancer therapy.

The role of engineering approaches in analysing cancer invasion and metastasis

In the past decade, novel materials, probes and tools have enabled fundamental and applied cancer researchers to take a fresh look at the complex problem of tumour invasion and metastasis. These new tools, which include imaging modalities, controlled but complex in vitro culture conditions, and the ability to model and predict complex processes in vivo, represent an integration of traditional with novel engineering approaches; and their potential effect on quantitatively understanding tumour progression and invasion looks promising.

Preparation, characterization and in vitro release study of a glutathione-dependent polymeric prodrug Cis-3-(9H-purin-6-ylthio)-acrylic acid-graft-carboxymethyl chitosan

In this work, an amphiphilic polymeric prodrug Cis-3-(9H-purin-6-ylthio)-acrylic acid-graft-carboxymethyl chitosan (PTA-g-CMCS) was designed and synthesized. In aqueous solution, this grafted polymer can self-assemble into spherical micelles with a size ranging from 104 to 285 nm and zeta potential ranging from -12.3 to -20.1 mV. For the release study, less than 24% of 6-Mercaptopurine (6-MP) was released from PTA-g-CMCS1 in the media containing 2 and 100 μM glutathione (GSH), whereas 37%, 54% and 75% of 6-MP was released from the media with GSH of 1, 2 and 10mM, respectively. Besides, pH and drug content of the polymeric prodrug only presented slight influence on the 6-MP release. MTT assay demonstrated that this system had higher inhibition ratio on HL-60 cells (human promyelocytic leukemia cells) in the presence of GSH and lower cytotoxicity on mouse fibroblast cell line (L929). Therefore, this nano-sized system is glutathione-dependent, and it can be employed as a potential carrier for the controlled release of 6-MP.

Self-organized nanogel from pullulan/pheophorbide-A conjugate as a macromolecular photodynamic agent

The potential of pullulan(PL)/pheophorbide-A(phA) nanogel (PL/phA) was evaluated as a macromolecular photosensitizer (PS) for photodynamic therapy (PDT). Two samples with different degrees of substitution of phA (PL/phA1 and 2) were synthesized and analyzed by 1H NMR. The mean diameters of self-organized nanogels from PL/phA1 and 2 in aqueous solution were approximately 100 and 160 nm with mono-size distribution, respectively. The changes in nanogel photoactivity such as fluorescence intensity and singlet oxygen (1O2) production were observed in the solvents, dimethyl sulfoxide (DMSO) and phosphate buffered saline (PBS). Although, their photoactivity in DMSO, which cannot form self-organized nanogels, was similar to that of free phA, activities were suppressed in the aqueous solution due to self-quenching between phAs similar to a fluorescence resonance energy transfer (FRET) effect. Moreover, as the nanogels were co-incubated with HeLa cells, the self-quenching effect gradually disappeared as a function of time. Based upon confocal microscopy and cytotoxicity results, we infer that the nanogels were internalized in cancer cells by endocytosis and then degraded by various enzymes in the endosome and lysosome, leading to the restoration of photoactivity. Therefore, the self-organized PL/phA nanogels may be recommended for development of new PDT with minimal unfavorable phototoxic affects.

Synthesis of curdlan-graft-poly(ethylene glycol) and formulation of doxorubicin-loaded core–shell nanoparticles

A new core–shell nanoparticle containing the chemotherapeutic drug doxorubicin was formulated via amphiphilic graft copolymer self-assembly using curdlan- graft-poly(ethylene glycol) (curdlan -g-PEG). The graft copolymer was synthesized through the dicyclohexylcarbodiimide ester linkage of carboxylated PEG to the hydroxyl groups of the curdlan backbone. The nanoparticles were 109.9 nm in size and encapsulated doxorubicin in high yield (4%–5% wt/wt). The nanoparticles also controlled the release of doxorubicin over 24 h with a release profile that followed a Fickian diffusion model. The biocompatibility of curdlan- g-PEG was confirmed by hemolysis assay. This is the first nanoparticle formulated using the hydrophobicity of curdlan for concealing the immunomodulatory potential of curdlan within the core.

Pharmacological, structural, and drug delivery properties and applications of 1,3-β-glucans

1,3-β-Glucans are a class of natural polysaccharides with unique pharmacological properties and the ability to form single- and triple-helical structures that can be formed into resilient gels with the application of heat and humidity. The pharmacological capabilities of 1,3-β-glucans include the impartation of tumor inhibition, resistance to infectious disease, and improvements in wound healing. Curdlan is a linear 1,3-β-glucan that has been used extensively to study the nature of these helical structures and gels, and Curdlan sulfates have found ongoing application in the inhibition of HIV infection. 1,3-β-Glucan gels have been used in food science as stabilizers and encapsulating agents, in nanoscience as scaffolds to build nanofibers and nanowires, and in drug delivery to form nanoparticles and create helical micelles encapsulating polynucleotides. 1,3-β-Glucans are beginning to have enormous significance due to their dual nature as structure-forming agents and pharmacological substances, and research is especially focused on the application of these polymers in animal nutrition and drug delivery.

Ocular drug delivery - a look towards nanobioadhesives

IMPORTANCE OF THE FIELD

A major challenge emanating in the design of topical ophthalmic preparations is their short precorneal residence time. Retention of a drug delivery system in the front of the eye is thus desirable. One solution identified to address this concern is a retentive system that can preferably be delivered in a liquid drop form and ultimately remain attached to the corneal tissue owing to incorporation of a bioadhesive component. Forward-thinking approaches are required to achieve advancements in this approach for the attainment of an effective drug concentration at the site of action. Accordingly, several investigators have identified the benefits of nanotechnology-based drug delivery systems for ophthalmic drug delivery.

AREAS COVERED IN THIS REVIEW

A concerted effort was made to review critically all 'nanobioadhesives', that is, nanosystems designed for ocular drug delivery with the goal of attaining prolonged ocular retention, in a systematic, chronological manner, from their reported point of inception to the present.

WHAT THE READER WILL GAIN

A perspective on possible future trends in this growing field of ocular drug delivery is formulated.

TAKE HOME MESSAGE

The importance of and need for new developments in the field of ocular nanobioadhesives is emphasized.

'Supramolecular wrapping chemistry' by helix-forming polysaccharides: a powerful strategy for generating diverse polymeric nano-architectures

We have exploited novel supramolecular wrapping techniques by helix-forming polysaccharides, β-1,3-glucans, which have strong tendency to form regular helical structures on versatile nanomaterials in an induced-fit manner. This approach is totally different from that using the conventional interpolymer interactions seen in both natural and synthetic polymeric architectures, and therefore has potential to create novel polymeric architectures with diverse and unexpected functionalities. The wrapping by β-1,3-glucans enforces the entrapped guest polymer to adopt helical or twisted conformations through the convergent interpolymer interactions. On the contrary, the wrapping by chemically modified semi-artificial β-1,3-glucans can bestow the divergent self-assembling abilities on the entrapped guest polymer to create hierarchical polymeric architectures, where the polymer/β-1,3-glucan composite acts as a huge one-dimensional building block. Based on the established wrapping strategy, we have further extended the wrapping techniques toward the creation of three-dimensional polymeric architectures, in which the polymer/β-1,3-glucan composite behaves as a sort of amphiphilic block copolymers. The present wrapping system would open several paths to accelerate the development of the polymeric supramolecular assembly systems, giving the strong stimuli to the frontier of polysaccharide-based functional chemistry.

Self-assembled nanoparticles of cholesterol-conjugated carboxymethyl curdlan as a novel carrier of epirubicin

The purpose of this study was to develop nanoparticles made of cholesterol-conjugated carboxymethyl curdlan (CCMC) entrapping epirubicin (EPB) and establish their in vitro and in vivo potential. CCMC was synthesized and characterized by Fourier transform infrared spectra (FT-IR) and proton nuclear magnetic resonance spectra ((1)H NMR). The degrees of substitution (DS) of the cholesterol moiety were 2.3, 3.5 and 6.4, respectively. EPB-loaded CCMC-3.5 nanoparticles were prepared by the remote loading method. The physicochemical characteristics, drug loading efficiency and drug release kinetics of EPB-loaded CCMC-3.5 nanoparticles were characterized. The in vitro release profiles revealed that EPB release was sensitive to the pH as well as the drug loading contents. The cellular cytotoxicity and cellular uptake were accessed by using human cervical carcinoma (HeLa) cells. The EPB-loaded CCMC-3.5 nanoparticles were found to be more cytotoxic and have a broader distribution within the cells than the free EPB. The in vivo pharmacokinetics and biodistribution were investigated after intravenous injection in rats. Promisingly, a 4.0-fold increase in the mean residence time (MRT), a 4.31-fold increase in the half-life time and a 6.69-fold increase in the area under the curve (AUC 0-->infinity) of EPB were achieved for the EPB-loaded CCMC-3.5 self-assembled nanoparticles compared with the free EPB. The drug level was significantly increased in liver at 24 and 72 h; however, it decreased in heart at 8 and 24 h compared with the free EPB. The in vivo anti-tumor study indicated that the EPB-loaded CCMC-3.5 self-assembled nanoparticles showed greater anti-tumor efficacy than the free EPB. Taken together, the novel CCMC self-assembled nanoparticles might have potential application as anti-cancer drug carriers in a drug delivery system due to good results in vitro and in vivo.

Preparation of sodium deoxycholate (DOC) conjugated heparin derivatives for inhibition of angiogenesis and cancer cell growth

We describe new DOC (sodium deoxycholate)-heparin nanoparticles for in vivo tumor targeting and inhibition of angiogenesis based on chemical conjugation and the enhanced permeability and retention (EPR) effect. Heparin has been used as a potent anticoagulant agent for 70 years, and has recently been found to inhibit the activity of growth factors which stimulate the smooth muscle cells around tumor. From the results, DOC and heparin were conjugated by bonding carboxyl groups of heparin with amine groups of aminated sodium deoxycholate. Larger antitumor effects of the DOC-heparin VI (8.5 mol of DOC coupled with 1.0 mol heparin) were achieved in animal studies, compared to heparin alone. We confirmed that the conjugated heparin retained its ability to inhibit binding with angiogenic factor, showing a significant decrease in endothelial tubular formation. These results provide new insights into the nontoxic anticancer drug carrier as well as the design of multifunctional bioconjugates for targeted drug delivery.