Synthesis of chitosan‐graft‐β‐cyclodextrin for improving the loading and release of doxorubicin in the nanopaticles

Chitosan‐graft‐β‐cyclodextrin (CS‐g‐β‐CD) copolymer was synthesized by conjugating β‐cyclodextrins to chitosan molecules through click chemistry. The copolymer structure was characterized by Fourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance (NMR). CS‐g‐β‐CD/CMC nanoparticles were prepared by a polyelectrolyte complexation process in aqueous solution between CS‐g‐β‐CD copolymer and carboxymethyl chitosan (CMC), which was used to load anticancer drug (Doxorubicin hydrochloride, DOX·HCl) with hydrophobic group. The particle size, surface charge, zeta potential, and morphology of the nanoparticles were characterized with dynamic light scattering. The drug loading efficiency and in vitro release of DOX·HCl of the nanoparticles were measured by ultraviolet spectrophotometer. The results demonstrated that the size, surface charge and drug loading efficiency of the nanoparticles could be modulated by the fabrication conditions. The drug loading efficiency of CS‐g‐β‐CD/CMC nanoparticles was improved from 52.7% to 88.1% because of the presence of β‐CD moieties with hydrophobic cavities, which can form inclusion complexes with the drug molecules. The in vitro release results showed that the CS‐g‐β‐CD/CMC nanoparticles released DOX·HCl in a controlled manner, importantly overcoming the initial burst effect. These nanoparticles possess much potential to be developed as anticancer drug delivery systems, especially those drugs with hydrophobic group. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 41034.     

Preparation and characterization of venlafaxine hydrochloride‐loaded chitosan nanoparticles and in vitro release of drug

The venlafaxine hydrochloride (VHL)‐loaded chitosan nanoparticles were prepared by ionic gelation of chitosan (CS) using tripolyphosphate (TPP). The nanoparticles were characterized using FTIR, differential scanning calorimetry, X‐ray diffraction, dynamic light scattering, transmission electron microscopy, and X‐ray photoelectron spectroscopy. The effect of concentration of CS, polyethylene glycol (PEG), VHL and CS/TPP mass ratio on the particle size and zeta potential of nanoparticles was examined. The particle size of CS/TPP nanoparticles and VHL‐loaded CS/TPP nanoparticles was within the range of 200–400 nm with positive surface charge. In the case of VHL‐loaded nanoparticles and PEG‐coated CS/TPP nanoparticles, the particle size increases and surface charge decreases with increasing concentration of VHL and PEG. Both placebo and VHL‐loaded CS/TPP nanoparticles were observed to be spherical in nature. PEG coating on the surface of CS/TPP nanoparticles was confirmed by XPS analysis. Maximum drug entrapment efficiency (70%) was observed at 0.6 mg/mL drug concentration. In vitro drug release study at 37°C ± 0.5°C and pH 7.4 exhibited initial burst release followed by a steady release. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

PEGylated chitosan microspheres as mucoadhesive drug‐delivery carriers for puerarin

PEGylated chitosans with different degrees of grafting were synthesized, and the application potential of microspheres based on PEGylated chitosan as mucoadhesive drug‐delivery carriers for puerarin was investigated. Compared with chitosan microspheres, PEGylated chitosan microspheres (PCMs) exhibited better physical stability and higher swelling capacity, and the amount of water uptake increased as the content of poly(ethylene glycol) methyl ether in the microspheres increased. PCMs showed obviously improved mucoadhesive behavior on a mucosa‐like surface. Puerarin was incorporated into the microspheres, and the release experiments in vitro showed that the PEGylation of chitosan accelerated puerarin release from the particles and decreased the retention of the drug. The abilities of all of the tested microspheres to open tight junctions and improve the permeability of puerarin were demonstrated with a Caco‐2 cell monolayer as an in vitro model. The amount of puerarin permeating across the Caco‐2 cell monolayer was significantly increased by the incorporation of puerarin into the PCMs. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42623.     

Preparation of chitosan‐coated magnetite nanoparticles and application for immobilization of laccase

In this study, immobilization of laccase (L) enzyme on magnetite (Fe₃O₄) nanoparticles was achieved, so that the immobilized enzyme could be used repeatedly. For this purpose, Fe₃O₄ nanoparticles were coated and functionalized with chitosan (CS) and laccase from Trametes versicolor was immobilized onto chitosan‐coated magnetic nanoparticles (Fe₃O₄‐CS) by adsorption or covalent binding after activating the hydroxyl groups of chitosan with carbodiimide (EDAC) or cyanuric chloride (CC). For chitosan‐coated magnetic nanoparticles, the thickness of CS layer was estimated as 1.0–4.8 nm by TEM, isoelectric point was detected as 6.86 by zeta (ζ)‐potential measurements, and the saturation magnetization was determined as 25.2 emu g^?1 by VSM, indicating that these nanoparticles were almost superparamagnetic. For free laccase and immobilized laccase systems, the optimum pH, temperature, and kinetic parameters were investigated; and the change of the activity against repeated use of the immobilized systems were examined. The results indicated that all immobilized systems retained more than 71% of their initial activity at the end of 30 batch uses. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Synthesis,characterization of biomimetic phosphorylcholine‐bound chitosan derivative and in vitro drug release of their nanoparticles

Novel water‐soluble biomimetic phosphorylcholine (PC)—bound chitosan derivatives (N‐PCCs) with different degree of substitution (DS) via a phosphoramide linkage between glucosamine and PC were synthesized through Atherton‐Todd reaction under the mild conditions, and structurally characterized by ¹H‐NMR, Fourier transform infrared (FTIR) spectroscopy, gel permeation chromatography (GPC), X‐ray diffraction (XRD), differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA). Their DS ranged from ～ 16 to ～ 42 mol % based on the ¹H‐NMR spectra. All these N‐PCCs with decreased crystallization showed excellent solubility in the aqueous solutions within a wide pH range (1–12). DSC and TGA results revealed that the thermal stability of N‐PCCs decreased with the increase of DS value. Further, N‐PCCs nanoparticles could be still formed in a spherical shape similar to chitosan nanoparticles by ionic gelation technique, observed by atomic force microscopy (AFM). Dynamic light scattering (DLS) results suggested that the zeta potential value of N‐PCCs nanoparticles decreased with the DS value increasing. Using 5‐fluorouracil (5‐Fu) as a model drug, in vitro drug release studies indicated that N‐PCCs nanoparticles exhibited a similar prolonged release profile as chitosan nanoparticles. The results suggested that N‐PCCs nanoparticles could be used as promising nanocarriers for drug delivery applications. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Evaluation of alginate–chitosan bioadhesive beads as a drug delivery system for the controlled release of theophylline

This study describes the preparation of mucoadhesive alginate–chitosan beads containing theophylline intended for colon‐specific delivery. The calcium alginate beads were coated with chitosan by the ionotropic hydrogelation method with a polyelectrolyte complex reaction between two oppositely charged polyions. The release profiles of theophylline from the beads were determined by ultraviolet–visible absorption measurement at 272 nm. Scanning electron microscopy was used for morphology observation. The in vitro mucoadhesive tests for particles were carried out with the freshly excised jejunum of Sprague‐Dawley rats. The bead particles, which ranged in size from 200 to 400 μm, exhibited excellent mucoadhesive properties. The results showed that the formulated coated beads succeeded in controlling the release of theophylline over a 24‐h period. In conclusion, the release of theophylline was found to be dependent on the composition of the beads, the component polymer and its possible interactions, and the bioadhesiveness. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Preparation,evaluation, and in vitro release study of O‐carboxymethyl chitosan nanoparticles loaded with gentamicin and salicylic acid

To inhibit the ototoxicity of gentamicin (GM) and overcome the drawback related to chitosan (CS) nanoparticles preparation in acid solution, O‐carboxymethyl chitosan (O‐CMC) nanoparticles loaded with GM and salicylic acid (SA) were prepared by ionic cross‐linking method using calcium chloride as crosslinking agent. The Fourier transform infrared (FTIR) spectroscopy and X‐ray diffraction (XRD) were used to analyze the reaction of O‐CMC and crosslinking agent. The parameters of preparation of the compound nanoparticles including the concentration of O‐CMC, the mass ratio of O‐CMC to calcium chloride, and the feed ratio of SA to GM were investigated. The results showed that the obtained nanoparticles had a high zeta potential and drug‐loading capacity. The nanoparticles were characterized by a spherical morphology, with average size ranging from 148 to 345 nm and a narrow particle size distribution. In vitro release studies in phosphate buffer saline (pH 7.4) evidenced a burst release in the first 1 h, followed by a sustained release in the residual time. The release amount of SA and GM were approximately equal in 24 h, which indicated that the SA‐ and GM‐loaded O‐CMC nanoparticles are a promising carrier system for inhibiting the ototoxicity of GM. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Preparation and evaluation of floating‐bioadhesive microparticles containing clarithromycin for the eradication of Helicobacter pylori

The development of a gastric floating‐bioadhesive drug delivery system to increase the efficacy of clarithromycin against Helicobacter pylori is described. Floating‐bioadhesive microparticles containing clarithromycin were prepared by a combined method of emulsification/evaporation and internal/ion gelation for the treatment of H. pylori infection. Ethylcellulose microspheres (EMs) were prepared by the dispersion of clarithromycin, ethylcellulose, and chitosan in dichloromethane and subsequent solvent evaporation. EMs were coated with alginate by the internal gelation process to obtain alginate–ethylcellulose microparticles (AEMs); then, AEMs were dispersed in a chitosan solution, and chitosan–alginate–ethylcellulose microparticles (CAEMs) were obtained by ion gelation to enhance the bioadhesive properties. The morphologies of EMs and CAEMs were investigated under optical and scanning electron microscopes. In vitro buoyancy and drug‐release testing confirmed the good floating and sustained‐release properties of CAEMs. About 74% of the CAEMs floated in an acetate buffer solution for 8 h, and 90% of the clarithromycin contained in the CAEMs was released within 8 h in a sustained manner. In vivo mucoadhesive testing showed that 61% of the CAEMs could be retained in the stomach for 4 h. Under a pretreatment with omeprazole, the clarithromycin concentration in gastric mucosa of the CAEM group was higher than that of the clarithromycin solution group. These results suggest that CAEMs might be a promising drug delivery system for the treatment of H. pylori infection. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 2226–2232, 2006     

Self‐aggregated nanoparticles of N‐dodecyl,N′‐glycidyl(chitosan) as pH‐responsive drug delivery systems for quercetin

In this study, pH‐responsive amphiphilic chitosan (CS) nanoparticles were used to encapsulate quercetin (QCT) for sustained release in cancer therapy. The novel CS derivatives were obtained by synthesis with 2,3‐epoxy‐1‐propanol, also known as glycidol, followed by acylation with dodecyl aldehyde. Characterization was performed by spectroscopic, viscosimetric, and size‐determination methods. Critical aggregation concentration, morphology, entrapment efficiency, drug release profile, cytotoxicity, and hemocompatibility studies were also carried out. The average size distribution of the self‐assembling nanoparticles measured by dynamic light scattering ranged from 140 to 300 nm. In vitro QCT release and Korsmeyer–Peppas model indicated that pH had a major role in drug release. Cytotoxicity assessments indicated that the nanoparticles were non‐cytotoxic. 3‐(4,5‐Dimethylthiazol‐2‐yl)‐2,5‐diphenyltetrazolium bromide assay further revealed that QCT‐loaded nanoparticles could inhibit MCF‐7 cell growth. In vitro erythrocyte‐induced hemolysis indicated the good hemocompatibility of the nanoparticles. These results suggest that the synthesized copolymers might be potential carriers for hydrophobic drugs in cancer therapy. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45678.     

Valproate‐Loaded hydrogel nanoparticles: Preparation and characterization

Developing a simple and efficient approach to formulate biodegradable nanoparticles for intravenous delivery of sodium valproate (a hydrophilic small molecule drug chronically used in epileptic patients), is the principal objective of the current study. To fabricate particles via ionotropic gelation approach, a polycation polymer (chitosan) along with a polyanion (tripolyphosphate) was utilized in the presence of sodium valproate, and the Taguchi experimental design method was drawn upon so as to determine the optimum conditions of nanoparticle generation. In the following step, the researchers investigated sodium valproate‐loaded nanoparticles to explore various features of the nanoparticles including drug loading parameters, particle size distribution, zeta‐potential, morphology, stability, yield, and in vitro drug release profile. Nanoparticles with sizes of 63 ± 1 nm (number‐based) and 79 ± 3.21 (volume‐based) were obtained with slightly negative zeta–potential, which was more positive in drug‐loaded nanoparticles than the unloaded ones. The TEM imaging of the hydrogel nanoparticles manifested spherical shapes and corroborated the size achieved via particle size analyzer. The loading efficiency, loading amount, and loading ratio were determined to be 21.81 ± 3.90%, 10.31 ± 1.82 (mg sodium valproate/g nanoparticle) and 23.70 ± 4.54%, respectively, in optimum conditions. Moreover, there was observed a gradual drug release for nearly a week consisting, in average, about 94.64 ± 2.71% of the nanoparticles' drug content. In a nutshell, the present study introduces a practical, simple, and effective ionotropic gelation approach to generate sodium valproate‐loaded nanoparticles, leaving open a window of promising prospects in the field of intravenous long‐term delivery of this chronically used drug. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Physicochemical characterization and antioxidant activity of quercetin‐loaded chitosan nanoparticles

Quercetin is an abundant flavonoid in food plants with numerous biological activities and widely used as a potent antioxidant. Being sparingly soluble in water and subject to degradation in aqueous intestinal fluids, the absorption of quercetin is limited upon oral administration. In the present study, chitosan nanoparticles and quercetin‐loaded nanoparticles were prepared based on the ionic gelation of chitosan with tripolyphosphate anions. The encapsulation of quercetin in the chitosan nanoparticles were confirmed by differential scanning calorimetry, X‐ray powder diffractometry, Fourier transformed infrared spectroscopy, ultraviolet‐visible spectrum, and fluorescence spectrum. The morphology of the nanoparticles was characterized by atomic force microscopy. The antioxidant activity of the quercetin‐nanoparticles was also evaluated in vitro by two different methods (free radical scavenging activity test and reducing power test), which indicates that inclusion of quercetin in chitosan nanopaticles may be useful in improving the bioavailabilty of quercetin. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2008     

Chitosan‐modified d‐α‐tocopheryl poly(ethylene glycol) 1000 succinate‐b‐poly(ε‐caprolactone‐ran‐glycolide) nanoparticles for the oral chemotherapy of bladder cancer

Oral chemotherapy is quickly emerging as an appealing option for cancer patients. It is less stressful because the patient has fewer hospital visits and can still maintain a close relationship with health care professionals. Three kinds of nanoparticles made from commercial poly(ε‐caprolactone) (PCL) and self‐synthesized d‐α‐tocopheryl poly(ethylene glycol) 1000 succinate ‐b‐poly(ε‐caprolactone‐ran‐glycolide) [TPGS‐b‐(PCL‐ran‐PGA)] diblock copolymer were prepared in this study for the oral delivery of antitumor agents, including chitosan‐modified PCL nanoparticles, nonmodified TPGS‐b‐(PCL‐ran‐PGA) nanoparticles, and chitosan‐modified TPGS‐b‐(PCL‐ran‐PGA) nanoparticles. First, the TPGS‐b‐(PCL‐ran‐PGA) diblock copolymer was synthesized and structurally characterized. Chitosan was adopted to extend the retention time at the cell surface and thus increase the chance of nanoparticle uptake by the gastrointestinal mucosa and improve the absorption of drugs after oral administration. The resulting TPGS‐b‐(PCL‐ran‐PGA) nanoparticles were found to be of spherical shape and around 200 nm in diameter with a narrow size distribution. The surface charge of the TPGS‐b‐(PCL‐ran‐PGA) nanoparticles could be reversed from anionic to cationic after surface modification. The chitosan‐modified TPGS‐b‐(PCL‐ran‐PGA) nanoparticles displayed a significantly higher level of cellular uptake compared with the chitosan‐modified PCL nanoparticles and nonmodified TPGS‐b‐(PCL‐ran‐PGA) nanoparticles. In vitro cell viability studies showed the advantages of the chitosan‐modified TPGS‐b‐(PCL‐ran‐PGA) nanoparticles over Taxol in terms of their cytotoxicity against human RT112 cells. In summary, the oral delivery of antitumor agents by chitosan‐modified TPGS‐b‐(PCL‐ran‐PGA) nanoparticles produced results that were promising for the treatment of patients with bladder cancer. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 2118–2126, 2013     

Preparation and efficacy of tumor vasculature‐targeted doxorubicin cationic liposomes coated by N‐trimethyl chitosan

Cationic liposomes (CLs) can accumulate in tumor vascular endothelial cells (VECs) to show high selective targeting ability. Therefore, chemotherapeutic agent‐loaded CLs are considered as new therapeutic vehicles to enhance the treatment efficacy. This study investigated the effect of N‐trimethyl chitosan (TMC), one of derivatives of chitosan with positive charge determined by its degree of quaternization (DQ), on preparing doxorubicin (DOX)‐loaded CLs. TMCs with various DQ, i.e., 20% (TMC20), 40% (TMC40), and 60% (TMC60) were synthesized and characterized by ¹HNMR. DOX‐loaded liposomes (DOXL) were prepared by ammonium sulfate gradients followed by TMC‐coating to obtain TMC‐coated DOXL with various positive surface charges. The morphology, size, ζ‐potential and drug release in vitro of TMC‐coated DOXL were studied compared with those of DOXL. Human umbilical vein endothelial cells (HUVECs) as cell model, the vascular targeting ability of TMC‐coated DOXL was evaluated in vitro. A solid tumor, formed by implantationmurine hepatoma cells (H₂₂) into mice, as tumor model, the tumor inhibition rate and tumor histological sections stained by HE of TMC‐coated DOXL group were researched compared with those of free DOX and DOXL group. It was found that with the increase of TMC's DQ, the positive surface charge of TMC‐coated DOXL was enhanced accordingly, which had little effect on DOX release in vitro while led to the significant increase of DOX uptake by HUVECs in vitro and the treatment effect on solid tumor in vivo. Especially, TMC‐coated DOXL showed better targeting ability to the nuclei compared with free DOX and DOXL, which could further enhance the efficacy of DOX in vivo. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Microstructural Effects on the Mechanical Properties of SiC‐15 vol% TiB2 Particulate‐Reinforced Ceramic Composites

The microstructures and mechanical properties were studied for two different SiC ceramics containing 15 vol% of TiB₂ particulates. The first was prepared from commercially available spray‐dried granules and the second by blending individual SiC and TiB₂ powders. The average TiB₂ particle sizes were 2.7 μm for the ceramic prepared from blended powders, which had a uniform distribution of TiB₂, and 2.3 μm for the ceramic prepared from spray‐dried granules, which had a nonuniform distribution of TiB₂ agglomerates. Although the two ceramics had hardness values of 26 GPa, the other properties were different. For example, the fracture toughness was 4.3 MPa·m^1/2 for the ceramic prepared from blended powders compared to 3.1 MPa·m^1/2 for the ceramic prepared from spray‐dried granules. In contrast, the Weibull modulus for the ceramic prepared from spray‐dried granules was 21 compared to 12 for the other. Calculations predicted spontaneous microcracking in the ceramic prepared from spray‐dried granules, which was confirmed by analysis of the microstructure. The presence of microcracks accounted for the higher Weibull modulus, but lower flexural strength, Young's modulus and fracture toughness for the ceramic prepared from spray‐dried granules.     

Mucoadhesive chitosan/OA nanoparticles charged with celecoxib inhibit prostaglandin E2 LPS‐induced in U937 cell line

The present study shows the potential of new carriers of celecocib (CEL) for prostaglandin E2 (PGE2) inhibition in U937 cell line. Self‐assembled nanoparticles based on oleic acid‐modified chitosan were covered with hyaluronic acid (HA) obtaining systems with spherical shape and particle size close to 300 nm. CEL was encapsulated and the encapsulation efficiency (%EE) was dependent of the drug solubility in acid media, reaching %EE of 75.5% and 58.2% to strong and weak acid, respectively. The covering with HA increased the mucoadhesive properties and, the cellular binding and cellular uptake in U937 cells. Nanoparticles prepared in strong acid presented zeta potential (ζ) of 43.8 ± 0.4 mV, which become toxic and stimulate the PGE2 production in U937 cells, at the concentration 1 mg/mL. However, nanoparticles prepared in weaker acid presented ζ of 36.5 ± 1.21 mV, showing nontoxic effect and inhibitory effect of PGE2 from 80.8 pg/mL until 43.4 pg/mL. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45288.     

pH‐sensitive Podophyllotoxin carrier for cancer cells specific delivery

A pH‐sensitive drug targeting system for solid tumors was established based on N‐isopropylacrylamide (NIPAAm) and chitosan conjugates. The mass ratio of NIPAAm and chitosan was adjusted to obtain super pH‐sensitive characteristic and the structure was studied by using Fourier transform infrared spectroscope to confirm the successful synthesis of the nanoparticles. The pH‐sensitive and drug release characteristics in vitro were studied as well. Human lung cancer cells A‐549 and human fibroblast were used to test the biocompatibility of blank and Podophyllotoxin (POD) loaded nanoparticles further to certificate the reliability of targeting acidic tumor extracellular pH. Results revealed that when charge ratio between NIPAAm and CS achieve 4:1(w/w), the drug‐loaded nanoparticles, which diameters ranged from 50 to 150 nm, exhibited super pH‐sensitive responses to tumor pH. Encapsulation and loading efficiencies were 63.7% and 2.4%, respectively. The cumulative release rate of POD, which significantly enhanced at pH 6.8 while decreased rapidly either below pH 6.5 or above pH 6.9 at 37°C. At pH 6.8, POD‐loaded nanoparticles showed cytotoxicity in MTT test and fluorescence microscopic study, comparable to that of free POD at the same POD concentrations, whereas at pH 7.4 there was little cytotoxicity at the tested concentration range. Thereby, the atoxic PNIPAAm‐g‐chitosan nanoparticle has the potentiality as a novel anticancer drugs carrier. POLYM. COMPOS., 2010. © 2009 Society of Plastics Engineers     

In vitro and in vivo investigational studies of a nanocomposite‐hydrogel‐based dressing with a silver‐coated chitosan wafer for full‐thickness skin wounds

A nanocomposite reservoir‐type hydrogel dressing of poly vinyl alcohol (PVA) was fabricated by a freeze–thaw method and loaded with silver‐nanoparticle‐coated chitosan wafers (Ag–CHWs). The Ag–CHWs were synthesized by a sonication technique with silver nitrate (AgNO₃) and chitosan powder. Scanning electron microscopy images showed silver nanoparticles (AgNPs) with a size range of 10 ± 4 nm on the surface of the chitosan wafers, and the antibacterial efficacy (minimum inhibitory concentration) of the Ag–CHWs was measured against Pseudomonas aeruginosa (32 µg/mL), Staphylococcus aureus, (30 µg/mL) and Escherichia coli (32 µg/mL). The antimicrobial PVA hydrogel showed an improved tensile strength (～0.28 MPa) and gel content (～92%) in comparison with the blank hydrogels. Full‐thickness‐excision wound studies of the nanocomposite dressing on Wistar rats revealed enhanced wound contraction, improved inflammation response, re‐epithelization rate, neoangiogenesis, and granulation tissue formation in comparison to the control group. A flexible, biocompatible, nanocomposite reservoir dressing not only established the chitosan as a stabilizer but also proved the efficacious and safe utility of AgNPs toward chronic wound management. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43472.     

Fabrication of galactosylated chitosan–5‐fluorouracil acetic acid based nanoparticles for controlled drug delivery

In this study, a novel type of macromolecular prodrug, N‐galactosylated chitosan (GC)?5‐fluorouracil acetic acid (FUA) conjugate based nanoparticles, was designed and synthesized as a carrier for hepatocellular carcinoma drug delivery. The GC–FUA nanoparticles were produced by an ionic crosslinking method based on the modified ionic gelation of tripolyphosphate with GC–FUA. The structure of the as‐prepared GC–FUA was characterized by Fourier transform infrared and ¹H‐NMR analyses. The average particle size of the GC–FUA nanoparticles was 160.1 nm, and their drug‐loading content was 21.22 ± 2.7% (n = 3). In comparison with that of the freshly prepared nanoparticles, this value became larger after 7 days because of the aggregation of the GC–FUA nanoparticles. An in vitro drug‐release study showed that the GC–FUA nanoparticles displayed a sustained‐release profile compared to 5‐fluorouracil‐loaded GC nanoparticles. All of the results suggest that the GC–FUA nanoparticles may have great potential for anti‐liver‐cancer applications. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42625.     

Multiscale modeling for surface composition of spray‐dried two‐component powders

Spray drying is a primary process for manufacturing various powder products. One of the most important properties of powders is the ability to get wet. Surface chemical composition critically influences this property. Furthermore, surface composition also influences the efficiency of production as it affects the stickiness of the powder. This work is an attempt to analyze the surface compositions of spray‐dried two‐component powders produced under various conditions using an innovative multiscale modeling approach. A molecular‐level geometrical interpretation is seamlessly coupled with a continuum diffusion model. The predictions are compared with the measurements done on the protein–lactose system using X‐ray photoelectron spectroscopy. Sample calculations for the system have demonstrated that the new approach helps reveal surface formation mechanisms much better than that explained with the monoscale continuum approach. This work provides a good basis for a fruitful area of study toward surface composition‐focused powder quality control that will have a positive impact in industries. © 2014 American Institute of Chemical Engineers AIChE J, 60: 2416–2427, 2014     

Fabrication of a Chitosan‐Coated Magnetic Nanobiocatalyst for Starch Hydrolysis

The preparation of chitosan‐coated magnetic nanoparticles (MNPs) and covalent immobilization of α‐amylase for starch hydrolysis was investigated. Surface morphology, chemical composition, and structural characteristics of the MNPs were analyzed by scanning electron microscopy, energy dispersion spectrometry, and X‐ray diffractometry, respectively. Surface functional groups of MNPs, chitosan‐coated MNPs, and α‐amylase‐immobilized MNPs were characterized by Fourier transform infrared spectroscopy. Response surface methodology based on three levels was implemented to optimize three immobilization conditions and a regression model was developed. α‐Amylase‐immobilized MNPs provided better stability towards pH and temperature. The prepared thermostable nanobiocatalyst is well‐suited for industrial processes involving starch hydrolysis.