Sharif Digital Repository

A pH-responsive drug delivery system based on core shell structure of mesoporous silica nanoparticle (MSN) and chitosan-PEG copolymer was prepared and characterized by Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), scanning electron microscope (SEM), and high-resolution transmission microscope (HR-TEM) techniques. In order to improve compatibility MSN and drug, mesoporous nanosilica was modified by 3-aminopropyl triethoxysilane. The release of erythromycin (a macrolide antibiotic) as a model drug was investigated in two pHs, 7.4 and 5.5  

Smart multilayered pH-sensitive nanocapsules were successfully fabricated using a Layer by Layer (LbL) process. The obtained products were characterized using FESEM, TEM, EDS and elemental mapping, zeta-potential, FTIR, TGA, SIMS and the Tafel polarization techniques. A 55% enhancement in ZrO2 particle size was detected in FESEM and TEM images with a corona view after the LbL process. EDS and elemental mapping analysis and measurements of zeta potential indicated the well-defined layered deposition. FTIR showed the electrostatic bonding between tolyltriazole (TTA) molecules and different overlapping layers. The thermal analysis and SIMS confirmed that 2.7% TTA loaded in nanocapsules. Tafel... 

A novel superabsorbent hydrogel composed of carboxymethylcellulose (CMC) and sodium alginate (Na-Alg) was prepared by using methylenebisacrylamide (MBA) as a crosslinking agent. Ammonium persulfate (APS) was used as an initiator. For investigation of the effect of reaction variables on water absorbency of the hydrogels, the synthetic conditions were systematically optimized through studying the influential factors, including temperature, Na-Alg/CMC weight ratio and concentration of MBA and APS. Increase in MBA and APS concentration results in the decrease in water absorbency of the hydrogels. The water absorbency of the hydrogels increased with increasing of reaction temperature and... 

In this study the bioleaching of a low-grade uranium ore containing 480 ppm uranium has been reported. The studies involved extraction of uranium using Acidithiobacillus ferrooxidans derived from the uranium mine samples. The maximum specific growth rate (μ max) and doubling time (t d) were obtained 0.08 h-1 and 8.66 h, respectively. Parameters such as Fe2+ concentration, particle size, temperature and pH were optimized. The effect of pulp density (PD) was also studied. Maximum uranium bio-dissolution of 100 ± 5 % was achieved under the conditions of pH 2.0, 5 % PD and 35 °C in 48 h with the particles of d 80 = 100 μm. The optimum concentration of supplementary Fe2+ was dependent to the PD.... 

Chitosan based polyseudorotaxane was designed as a pH-responsive supramolecular polymeric shell around the mesoporous silica-coated magnetic graphene oxide (Fe3O4@GO@mSiO2). It was used for doxorubicin delivery at cancerous tissue in a controlled manner. The core-shell nanocarrier was formed due to electrostatic interaction between chitosan and carboxylated surface of Fe3O4@GO@mSiO2. The maximum release occurred at pH 5.5 (pH of endosomes) because the shell collapsed at this pH. The drug nanocarrier has potential application in tumor therapy due to good pH-sensitive behavior, improved solubility and high colloidal stability in... 

In the present work a pH responsive drug nanocarrier based on magnetic mesoporous silica nanoparticles (MMSN) and polyethylene glycol-co-polyvinyl pyridine (PEG-co-PVP) was prepared. The core-shell nanocarrier was formed due to electrostatic interaction between protonated polyvinyl pyridine and surface modified MMSN with carboxylate groups. This carrier was used for pH-controllable doxorubicin release. The maximum release was occurred at pH 5.5 (pH of endosomes). This carrier was characterized by Fourier transform infrared spectroscopy, thermogravimetric analysis, UV-Vis spectrophotometer, scanning electron microscope, and high-resolution transmission electron microscope techniques. Also the... 

Storage conditions seem to be important in the long-term stability of nanoparticles (NPs). This work studies the effects of surfactants and storage container on particle size distribution and zeta potential during long-term storage of acid hydrolyzed potato starch NPs. The NPs were prepared from potato starch using acid hydrolysis and high-intensity ultrasonication. During the ultrasonic treatment, the surfactants were added dropwise to the solutions to reduce the size and stabilize the formed NPs. Particle size distribution, zeta potential, and FE-SEM were used to characterize the ensuing NPs. Additionally, a 5-month stability study was performed to evaluate the maintenance of potato starch... 

Breast cancer incidence has increased in recent decades. In the present study, an optimum formulation of chitosan (CS)-adorned niosome-based nanocarriers for co-delivery of doxorubicin (DOX) and vincristine (VIN) was developed for the treatment of breast cancer to reduce drug doses and overcome multidrug resistance. The three-level Box-Behnken method was utilized to optimize the particles in terms of size, polydispersity index (PDI), entrapment efficacy (EE (%)), and percent of drug release (%). The release rate of two drugs from CS-adorned nanoparticles (DOX+VIN/Nio/CS) in acidic and physiological pH is less than uncoated niosome (DOX+VIN/Nio). In addition, acidic pH increases the release... 

Purpose: The prime end of this study was to design a novel pH-sensitive as well as a PEGylated dendritic nanocarrier for both controllable and traceable gemcitabine delivery to cancerous cells. To accomplish this goal, we took advantage of a hybrid of nanoparticles including: mesoporous silica, graphene oxide and magnetite. Methods: The nanocarrier was prepared in a multi-step synthesis route. First, magnetite mesoporous silica was deposited on the graphene oxide matrix. Then, polyamidoamine dendrimers (up to generation 1.5) with pentaethylene hexamine end groups were grafted on the surface of the nanoparticles. In order to enhance the biostability, and as the next step, the nanocarrier was... 

There is a substantial volume of mobile phone waste every year. Due to the disadvantages of traditional methods, it is necessary to look for biological processes that are more eco-friendly and economical to recover metals from e-waste. Fungi provide large amounts of organic acids and dissolve metals but using sucrose in the medium is not economical. In this paper, the main objective is to find a suitable alternative carbon substrate instead of sucrose for fungi bioleaching of Ni and Cu in printed circuit boards (PCBs) of mobile phones using Penicillium simplicissimum. Four kinds of carbon sources (including sucrose, cheese whey, sugar, and sugar cane molasses) were selected. Also, pH and... 

Breast cancer is the most common invasive cancer in women and the second leading cause of cancer death in women after lung cancer. The purpose of this study is a targeted delivery toward in vitro (on MCF7 and 4T1 breast cancer cell lines) through niosomes-based nanocarriers. To this end, different bioactive molecules, including hyaluronic acid (HA), folic acid (FA), and polyethylene glycol (PEG), were used and compared for surface modification of niosomes to enhance endocytosis. FA-functionalized niosomes (Nio/5-FU/FA) were able to increase cell cytotoxicity and reduce cell migration and invasion compared to PEG-functionalized niosomes (Nio/5-FU/PEG), and HA-functionalized niosomes... 

A novel magnetic nanocarrier with long spacer length and high colloidal stability has been prepared for effective delivery of doxorubicin (DOX). First, poly(amidoamine) (PAMAM) dendrimer was grown up onto the surface of superparamagnetic iron oxide nanoparticles to increase the loading amount of amine groups. Then, terminal amine groups were functionalized by polyethylene glycol dimethylester to increase the spacer length. Then anticancer drug DOX was covalently attached onto the system by hydrazone bond to forms a pH-sensitive nanocarrier. This system is designed to combine the advantage of magnetic targeting, high drug loading capacity, and controlled release  

This work focused on the design of new pH-responsive nanoparticles for controlled delivery of anticancer drug doxorubicin (Dox). Nanoparticles of poly(methacrylic acid)-polysorbate 80-grafted starch (PMAA-PS 80-g-St) were synthesized by using a one-pot method that enabled simultaneous grafting of PMAA and PS 80 onto starch and nanoparticle formation in an aqueous medium. The particles were characterized by FTIR, 1H NMR, TEM, DLS, and potentiometric titration. Dox loading and in vitro release from the nanoparticles were investigated. The FTIR and 1H NMR confirmed the chemical composition of the graft terpolymer. The nanoparticles were relatively spherical with narrow size distribution and...