Bovine serum albumin (BSA) release profiles of (a) chitosan and (b) LA-g-chitosan nanoparticles at different BSA loading concentrations

Data shown are the mean ± standard deviation (n=3).<p><b>Copyright information:</b></p><p>Taken from "Chitosan and lactic acid-grafted chitosan nanoparticles as carriers for prolonged drug delivery"</p><p></p><p>International Journal of Nanomedicine 2006;1(2):181-187.</p><p>Published online Jan 2006</p><p>PMCID:PMC2426789.</p><p>© 2006 Dove Medical Press Limited. All rights reserved</p

Chitosan and lactic acid-grafted chitosan nanoparticles as carriers for prolonged drug delivery-1

<p><b>Copyright information:</b></p><p>Taken from "Chitosan and lactic acid-grafted chitosan nanoparticles as carriers for prolonged drug delivery"</p><p></p><p>International Journal of Nanomedicine 2006;1(2):181-187.</p><p>Published online Jan 2006</p><p>PMCID:PMC2426789.</p><p>© 2006 Dove Medical Press Limited. All rights reserved</p

Hexanoyl-Chitosan-PEG Copolymer Coated Iron Oxide Nanoparticles for Hydrophobic Drug Delivery

Nanoparticle (NP) formulations may be used to improve in vivo efficacy of hydrophobic drugs by circumventing solubility issues and providing targeted delivery. In this study, we developed a hexanoyl-chitosan-PEG (CP6C) copolymer coated, paclitaxel (PTX)-loaded, and chlorotoxin (CTX) conjugated iron oxide NP (CTX-PTX-NP) for targeted delivery of PTX to human glioblastoma (GBM) cells. We modified chitosan with polyethylene glycol (PEG) and hexanoyl groups to obtain the amphiphilic CP6C. The resultant copolymer was then coated onto oleic acid-stabilized iron oxide NPs (OA-IONP) via hydrophobic interactions. PTX, a model hydrophobic drug, was loaded into the hydrophobic region of IONPs. CTX-PTX-NP showed high drug loading efficiency (>30%), slow drug release in PBS and the CTX-conjugated NP was shown to successfully target GBM cells. Importantly, the NPs showed great therapeutic efficacy when evaluated in GBM cell line U-118 MG. Our results indicate that this nanoparticle platform could be used for loading and targeted delivery of hydrophobic drugs

Nanofiber-Based in Vitro System for High Myogenic Differentiation of Human Embryonic Stem Cells

Myogenic progenitor cells derived from human embryonic stem cells (hESCs) can provide unlimited sources of cells in muscle regeneration but their clinical uses are largely hindered by the lack of efficient methods to induce differentiation of stem cells into myogenic cells. We present a novel approach to effectively enhance myogenic differentiation of human embryonic stem cells using aligned chitosan-polycaprolactone (C-PCL) nanofibers constructed to resemble the microenvironment of the native muscle extracellular matrix (ECM) in concert with Wnt3a protein. The myogenic differentiation was assessed by cell morphology, gene activities, and protein expression. hESCs grown on C-PCL uniaxially aligned nanofibers in media containing Wnt3a displayed an elongated morphology uniformly aligned in the direction of fiber orientation, with increased expressions of marker genes and proteins associated with myogenic differentiation as compared to control substrates. The combination of Wnt3a signaling and aligned C-PCL nanofibers resulted in high percentages of myogenic-protein expressing cells over total treated hESCs (83% My5, 91% Myf6, 83% myogenin, and 63% MHC) after 2 days of cell culture. Significantly, this unprecedented high-level and fast myogenic differentiation of hESC was demonstrated in a culture medium containing no feeder cells. This study suggests that chitosan-based aligned nanofibers combined with Wnt3a can potentially act as a model system for embryonic myogenesis and muscle regeneration

Chitosan-Based Thermoreversible Hydrogel as an <i>in Vitro</i> Tumor Microenvironment for Testing Breast Cancer Therapies

Breast cancer is a major health problem for women worldwide. Although <i>in vitro</i> culture of established breast cancer cell lines is the most widely used model for preclinical assessment, it poorly represents the behavior of breast cancers <i>in vivo</i>. Acceleration of the development of effective therapeutic strategies requires a cost-efficient <i>in vitro</i> model that can more accurately resemble the <i>in vivo</i> tumor microenvironment. Here, we report the use of a thermoreversible poly­(ethylene glycol)-<i>g</i>-chitosan hydrogel (PCgel) as an <i>in vitro</i> breast cancer model. We hypothesized that PCgel could provide a tumor microenvironment that promotes cultured cancer cells to a more malignant phenotype with drug and immune resistance. Traditional tissue culture plates and Matrigel were applied as controls in our studies. <i>In vitro</i> cellular proliferation and morphology, the secretion of angiogenesis-related growth factors and cytokines, and drug and immune resistance were assessed. Our results show that PCgel cultures promoted tumor aggregate formation, increased secretion of various angiogenesis- and metastasis-related growth factors and cytokines, and increased tumor cell resistance to chemotherapeutic drugs and immunotherapeutic T cells. This PCgel platform may offer a valuable strategy to bridge the gap between standard <i>in vitro</i> and costly animal studies for a wide variety of experimental designs

Single-Chain Semiconducting Polymer Dots

This work describes the preparation and validation of single-chain semiconducting polymer dots (<i>s</i>Pdots), which were generated using a method based on surface immobilization, washing, and cleavage. The <i>s</i>Pdots have an ultrasmall size of ∼3.0 nm as determined by atomic force microscopy, a size that is consistent with the anticipated diameter calculated from the molecular weight of the single-chain semiconducting polymer. <i>s</i>Pdots should find use in biology and medicine as a new class of fluorescent probes. The FRET assay this work presents is a simple and rapid test to ensure methods developed for preparing <i>s</i>Pdot indeed produced single-chain Pdots as designed

In Vivo Safety Evaluation of Polyarginine Coated Magnetic Nanovectors

Safety and efficacy are of critical importance to any nanomaterial-based diagnostic and therapy. The innocuity and functionality of a nanomaterial in vivo is largely dependent on the physicochemical properties of the material, particularly its surface coating. Here, we evaluated the influence of polycationic coating on the efficacy, clearance organ uptake, and safety of magnetic nanovectors designed for siRNA delivery. Polyethylene glycol (PEG) coated superparamagnetic iron oxide nanoparticles (NPs) of 12 nm in core diameter were modified with a polycationic coating of either poly-l-arginine (pArg) or polyethylenimine (PEI) and further covalently functionalized with siRNA oligonucleotides. The produced NP-pArg-siRNA and NP-PEI-siRNA nanovectors were similar in hydrodynamic size (21 and 22 nm, respectively) but significantly differed in zeta potentials (+2.1 mV and +29.8 mV, respectively). Fluorescence quantification assays revealed that the NP-pArg-siRNA nanovector was 3-fold more potent than NP-PEI-siRNA in delivering siRNA and 1.8-fold more effective in gene silencing when tested in rat C6 glioblastoma cells. In vivo, both nanovector formulations were similarly taken up by the spleen and liver as determined by histopathological and hemopathological assays. However, PEI coated nanovectors elicited severe hemoincompatibility and damage to the liver and spleen, while pArg coated nanovectors were found to be safe and tolerable. Combined, our findings suggest that polycationic coatings of pArg were more effective and safer than commonly used PEI coatings for preparation of nanovectors. The NP-pArg-siRNA nanovector formulation developed here shows great potential for in vivo based biomedical applications

pH-Sensitive O6-Benzylguanosine Polymer Modified Magnetic Nanoparticles for Treatment of Glioblastomas

Nanoparticle-mediated delivery of chemotherapeutics has demonstrated potential in improving anticancer efficacy by increasing serum half-life and providing tissue specificity and controlled drug release to improve biodistribution of hydrophobic chemotherapeutics. However, suboptimal drug loading, particularly for solid core nanoparticles (NPs), remains a challenge that limits their clinical application. In this study we formulated a NP coated with a pH-sensitive polymer of O⁶-methylguanine-DNA methyltransferase (MGMT) inhibitor analog, dialdehyde modified O⁶-benzylguanosine (DABGS) to achieve high drug loading, and polyethylene glycol (PEG) to ameliorate water solubility and maintain NP stability. The base nanovector consists of an iron oxide core (9 nm) coated with hydrazide functionalized PEG (IOPH). DABGS and PEG-dihydrazide were polymerized on the iron oxide nanoparticle surface (IOPH-pBGS) through acid-labile hydrazone bonds utilizing a rapid, freeze–thaw catalysis approach. DABGS polymerization was confirmed by FTIR and quantitated by UV–vis spectroscopy. IOPH-pBGS demonstrated excellent drug loading of 33.4 ± 5.1% by weight while maintaining small size (36.5 ± 1.8 nm). Drug release was monitored at biologically relevant pHs and demonstrated pH dependent release with maximum release at pH 5.5 (intracellular conditions), and minimal release at physiological pH (7.4). IOPH-pBGS significantly suppressed activity of MGMT and potentiated Temozolomide (TMZ) toxicity in vitro, demonstrating potential as a new treatment option for glioblastomas (GBMs)

Targeting of Primary Breast Cancers and Metastases in a Transgenic Mouse Model Using Rationally Designed Multifunctional SPIONs

Breast cancer remains one of the most prevalent and lethal malignancies in women. The inability to diagnose small volume metastases early has limited effective treatment of stage 4 breast cancer. Here we report the rational development and use of a multifunctional superparamagnetic iron oxide nanoparticle (SPION) for targeting metastatic breast cancer in a transgenic mouse model and imaging with magnetic resonance (MR). SPIONs coated with a copolymer of chitosan and polyethylene glycol (PEG) were labeled with a fluorescent dye for optical detection and conjugated with a monoclonal antibody against the neu receptor (NP-neu). SPIONs labeled with mouse IgG were used as a nontargeting control (NP-IgG). These SPIONs had desirable physiochemical properties for <i>in vivo</i> applications such as near neutral zeta potential and hydrodynamic size around 40 nm and were highly stable in serum containing medium. Only NP-neu showed high uptake in neu expressing mouse mammary carcinoma (MMC) cells which was reversed by competing free neu antibody, indicating their specificity to the neu antigen. <i>In vivo</i>, NP-neu was able to tag primary breast tumors and significantly, only NP-neu bound to spontaneous liver, lung, and bone marrow metastases in a transgenic mouse model of metastatic breast cancer, highlighting the necessity of targeting for delivery to metastatic disease. The SPIONs provided significant contrast enhancement in MR images of primary breast tumors; thus, they have the potential for MRI detection of micrometastases and provide an excellent platform for further development of an efficient metastatic breast cancer therapy

Approach to Rapid Synthesis and Functionalization of Iron Oxide Nanoparticles for High Gene Transfection

Surface functionalization of theranostic nanoparticles (NPs) typically relies on lengthy, aqueous postsynthesis labeling chemistries that have limited ability to fine-tune surface properties and can lead to NP heterogeneity. The need for a rapid, simple synthesis approach that can provide great control over the display of functional moieties on NP surfaces has led to increased use of highly selective bioorthoganol chemistries including metal-affinity coordination. Here we report a simple approach for rapid production of a superparamagnetic iron oxide NPs (SPIONs) with tunable functionality and high reproducibility under aqueous conditions. We utilize the high affinity complex formed between catechol and Fe^(III) as a means to dock well-defined catechol modified polymer modules on the surface of SPIONs during sonochemical coprecipitation synthesis. Polymer modules consisted of chitosan and poly­(ethylene glycol) (PEG) copolymer (CP) modified with catechol (CCP), and CCP functionalized with cationic polyethylenimine (CCP-PEI) to facilitate binding and delivery of DNA for gene therapy. This rapid synthesis/functionalization approach provided excellent control over the extent of PEI labeling, improved SPION magnetic resonance imaging (MRI) contrast enhancement and produced an efficient transfection agent