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surface-modification
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hysical and Chemical Surface Modification of Titanium by Nanostructured Materials, and Biological Characterization for Use in Bone Tissue Implants
, Ph.D. Dissertation Sharif University of Technology ; Bagheri, Reza (Supervisor) ; Vossoughi, Manochehr (Supervisor) ; Samadi Kuchaksaraei, Ali (Supervisor)
Abstract
According to human needs and in line with the development of advanced technologies, different biomedical Engineering fields like hard tissue implants are growing rapidly. Despite significant biotechnology Developments in recent years, some problems to the recognition of implants related osseointegration phenomena persist. The deficient osseointegration and implant-associated infections are key issues for the long-term clinical success of titanium and titanium alloy implants, while development of multifunctional surfaces that can simultaneously overcome these problems remains highly challenging. Therefore, the ultimate goal of this paper was to improve bone cell attachment and simultaneously...
Effect of Surface Treatment and Tool Rotational Speed in Aluminum to Polymeric Composite Joint Produced Using Friction Stir/Adhesive Hybrid Process
, M.Sc. Thesis Sharif University of Technology ; Movahedi, Mojtaba (Supervisor)
Abstract
Today because of increasing use of fuel, environmental problems and problems due to heavy structures in different industries it is important to use structures with high specific strength. Using different materials in structures like polymers accompanying aluminum could be useful. Polymers are light, heat insulating and have a high corrosion resistance. Polypropylene is one of the useful polymers which can have high impact energy and strength via adding Elastomer and Talc powder, relatively. One of the common ways in joining metal to polymer uses adhesive. It has variety of benefits such as low distortion in joining, different materials joints and having joints with complex geometry. Welding...
Synthesis and Investigation of Properties of Biocompatible Polyurethane Acrylate Based Nanocomposites/Cellulose Nanocrystals
, M.Sc. Thesis Sharif University of Technology ; Shojaei, Akbar (Supervisor) ; Salkhi, Samaneh (Co-Supervisor)
Abstract
Bio-based shape memory polymers with fast-response have high potential for use in medical applications. In this study, biocompatible and biodegradable nanocomposites based on shape memory polyurethane acrylates (SMPUA)/cellulose nanocrystals (CNC), were synthesized by in-situ polymerization. CNC is a natural and renewable nanoparticle that has been considered for medical applications due to its excellent mechanical and biological properties and surface chemistry. At the first phase of this study, in order to synthesize UV-curable shape memory polyurethane acrylate, polycaprolactone diol (PCL-Diol), hexamethylene diisocyanate (HDI) and hydroxyethyl methacrylate (HEMA) were used as an reactive...
Specific targeting delivery to MUC1 overexpressing tumors by albumin-chitosan nanoparticles conjugated to DNA aptamer
, Article International Journal of Pharmaceutics ; Volume 515, Issue 1-2 , 2016 , Pages 607-615 ; 03785173 (ISSN) ; Mohammadi, A ; Atyabi, F ; Nabavi, S. M ; Ebrahimi, S. M ; Shahmoradi, E ; Shiri Varnamkhasti, B ; Ghahremani, M. H ; Dinarvand, R ; Sharif University of Technology
Elsevier B.V
2016
Abstract
Chitosan-coated human serum albumin nanoparticles were functionalized by MUC1 aptamer to obtain a selective drug carrier toward cancers overexpressing MUC1. The negative charges of albumin nanoparticles were shifted to positive charges by surface modification with chitosan, and MUC1 was conjugated through an acrylate spacer. The cytotoxicity of targeted nanoparticles was significantly more than non-aptamer nanoparticles, and also the chitosan-coated nanoparticles had more cytotoxic effects than the negatively charged albumin nanoparticles. The IC50 of targeted nanoparticles was 28 and 26% of free paclitaxel in MCF7 and T47D cells at 48 h, respectively. Confocal laser scanning electron...
Environmentally responsive surface-modified silica nanoparticles for enhanced oil recovery
, Article Journal of Nanoparticle Research ; Volume 18, Issue 9 , 2016 ; 13880764 (ISSN) ; Mohammadi, A ; Sharif University of Technology
Springer Netherlands
Abstract
Environmentally responsive surface-modified nanoparticles are colloidal nanoparticles coated with, at least, two physicochemically distinct surface groups. Recent advances in the synthesis and production of nanoparticles have enabled the production of environmentally responsive surface-modified nanoparticles with both hydrophilic and hydrophobic surface groups. These nanoparticles act like colloidal surfactants. In this paper, environmentally responsive surface-modified silica nanoparticles are synthesized and used for enhancement of oil recovery. For this purpose, silica nanoparticles are coated with polyethylene glycol chains as hydrophilic agent and propyl chains as hydrophobic agent at...
In vitro biological outcome of laser application for modification or processing of titanium dental implants
, Article Lasers in Medical Science ; Volume 32, Issue 5 , 2017 , Pages 1197-1206 ; 02688921 (ISSN) ; Farahmand, F ; Tabatabaei, F. S ; Sharif University of Technology
Abstract
There are numerous functions for laser in modern implant dentistry including surface treatment, surface coating, and implant manufacturing. As laser application may potentially improve osseointegration of dental implants, we systematically reviewed the literature for in vitro biological responses to laser-modified or processed titanium dental implants. The literature was searched in PubMed, ISI Web, and Scopus, using keywords “titanium dental implants,” “laser,” “biocompatibility,” and their synonyms. After screening the 136 references obtained, 28 articles met the inclusion criteria. We found that Nd:YAG laser was the most commonly used lasers in the treatment or processing of titanium...
Surface modification of polysulfone ultrafiltration membranes by free radical graft polymerization of acrylic acid using response surface methodology
, Article Journal of Polymer Research ; Volume 26, Issue 9 , 2019 ; 10229760 (ISSN) ; Asadollahi, M ; Mousavi, S. A ; Bastani, D ; Aghaeifard, F ; Sharif University of Technology
Springer Netherlands
2019
Abstract
In this research, polysulfone (PSf) ultrafiltration (UF) membranes were prepared by a phase inversion method. Surface modification of the PSf membranes was carried out via grafting of acrylic acid as a hydrophilic monomer by free radical graft polymerization initiated by redox reaction. A central composite design (CCD) of response surface methodology (RSM) was applied to design the experiments. The process variables were acrylic acid concentration (CAA), redox system contact time (T1), and acrylic acid polymerization time (T2), while the contact angle (CA), pure water flux (PWF), and flux recovery ratio (FRR) were considered as the responses. Analysis of variance (ANOVA) demonstrated that...
Effects of severe plastic deformation on pre-osteoblast cell behavior and proliferation on AISI 304 and Ti-6Al-4V metallic substrates
, Article Surface and Coatings Technology ; Volume 366 , 2019 , Pages 204-213 ; 02578972 (ISSN) ; Aydın, H. M ; Maleki, E ; Varol, R ; Unal, O ; Sharif University of Technology
Elsevier B.V
2019
Abstract
In this study, titanium alloy (Ti-6Al-4V) and austenitic stainless steel (AISI 304) biomedical alloys were subjected to surface severe plastic deformation (SSPD) via severe shot peening (SSP) with the conditions of A28-30 Almen intensity. SSP is widely accepted as much more effective than the conventional surface modification techniques since it forms a nano-grain layer with large number of dislocations and grain boundaries. The SSP treatment in this study was led to a very thin rough layer in Ti-6Al-4V titanium alloy compared to that of AISI 304. The thicker layer of AISI 304 was created by twin-twin intersections and a martensite structure transformations. SSP treatment was resulted in a...
Improvement of performance and fouling resistance of polyamide reverse osmosis membranes using acrylamide and TiO2 nanoparticles under UV irradiation for water desalination
, Article Journal of Applied Polymer Science ; Volume 137, Issue 11 , 2020 ; Bastani, D ; Mousavi, S. A ; Heydari, H ; Vaghar Mousavi, D ; Sharif University of Technology
John Wiley and Sons Inc
2020
Abstract
The purpose of this research is to explain the surface modification of fabricated polyamide reverse osmosis (RO) membranes using UV-initiated graft polymerization at different irradiation times (15, 30, 60, and 90 s) and various acrylamide concentrations (10, 20, and 30 g L−1). Also, coating of membranes surface with various concentrations of TiO2 nanoparticles (10, 20, 30, and 50 ppm) followed by the same UV irradiation times was investigated. After that, the membranes modification was done by grafting of acrylamide blended with TiO2 nanoparticles via UV irradiation. The characterization of membranes surface properties and their performance were systematically carried out. The results...
Enhancement in microstructural and mechanical performance of AA7075 aluminum alloy via severe shot peening and ultrasonic nanocrystal surface modification
, Article Applied Surface Science ; Volume 528 , 2020 ; Karademir, I ; Husem, F ; Maleki, E ; Karimbaev, R ; Amanov, A ; Unal, O ; Sharif University of Technology
Elsevier B.V
2020
Abstract
In this experimental study, AA7075 aluminum alloy was subjected to pure severe shot peening (SSP), pure ultrasonic nanocrystalline surface modification (UNSM) and the combination of these two treatments. The treated specimens were analyzed with detailed microstructure analysis, micro-hardness, surface roughness, XRD investigations and wear-friction tests. The results demonstrated that UNSM exhibited fine surface finish and provided minimum surface roughness with the Ra value of 0.8 µm. Moreover, UNSM played an important role in the reduction of Ra as a secondary treatment. Electron back scatter diffraction (EBSD) analysis, full width at half maximum (FWHM) evaluations and compressive...
CaTiO3/α-TCP coatings on CP-Ti prepared via electrospinning and pulsed laser treatment for in-vitro bone tissue engineering
, Article Surface and Coatings Technology ; Volume 401 , 2020 ; Esfahani, H ; Sheikhi, M ; Mohammadi, M ; Sharif University of Technology
Elsevier B.V
2020
Abstract
In this study, the in-vitro bone regeneration ability of commercial pure titanium (CP-Ti) surface modified via electrospun polyvinylidene/hydroxyapatite (PVP/HA) masking and subsequent Nd-YAG pulsed laser treatment was investigated. The ratio of HA to PVP played a significant role in achieving a perfect homogenous mask on the CP-Ti. In the laser treatment process, the parameter of area scanning speed (ASS) had an important influence on the final surface morphology. A favorable range was defined for this parameter where these two conditions were satisfied: no PVP remaining and no severe substrate melting. Within a favorable range of ASS, as decreasing ASS exchanged the surface structure from...
Heavy metal removal from water and wastewater using raw and modified diatomite
, Article International Journal of Engineering, Transactions B: Applications ; Volume 20, Issue 2 , 2007 , Pages 141-146 ; 1728-144X (ISSN) ; Nahid, P ; Sharif University of Technology
Materials and Energy Research Center
2007
Abstract
Heavy metal removal from water and wastewater was investigated by using raw and modified diatomite from Iranian mines. Modification of diatomite was done by impregnating the diatomite surface with 0.35 g of manganese oxide in one gram of diatomite. This modified diatomite was named Mn-Diatomite. The surface area measurements for Mn-diatomite showed a 2.2 fold increase, hence higher removal capacity for the heavy metals. The results of the removal showed an increase in adsorption capacity which was for Pb2+ about 40 mg/g, for Ni 2+ about 34mg/g and for Cu2+ about 33mg/g. The filtration quality of diatomite was significantly enhanced with surface modification by manganese oxide
Smoothing and coverage improvement of SnO2 electron transporting layer by NH4F treatment: Enhanced fill factor and efficiency of perovskite solar cells
, Article Solar Energy ; Volume 228 , 2021 , Pages 253-262 ; 0038092X (ISSN) ; Zamani Meymian, M. R ; Mohamadkhani, F ; Taghavinia, N ; Sharif University of Technology
Elsevier Ltd
2021
Abstract
Surface modification of SnO2 electron transporting layer (ETL) plays a critical role in the performance of SnO2-based planar perovskite solar cells (PSC). Here, we show how long-time NH4F-based water bath treatment of SnO2 layer makes smoothing and morphological improvements and enhances the device performance. Recently it was shown that short-time NH4F treatment (2 sec) with spin coating method reduces interface traps by improving surface chemistry. Here we observe the smoothing of SnO2 films as a result of long-time NH4F treatment, which could be a result of a slight etching-deposition process. Absorption and resistivity measurements indicate that SnO2 etching process is involved in...
Recent advances in the modification of carbon-based quantum dots for biomedical applications
, Article Materials Science and Engineering C ; Volume 120 , 2021 ; 09284931 (ISSN) ; Sedighi, O ; Tabatabaei Rezaei, N ; Abedini, A. A ; Malek Khachatourian, A ; Toprak, M. S ; Seifalian, A ; Sharif University of Technology
Elsevier Ltd
2021
Abstract
Carbon-based quantum dots (CDs) are mainly divided into two sub-groups; carbon quantum dots (CQDs) and graphene quantum dots (GQDs), which exhibit outstanding photoluminescence (PL) properties, low toxicity, superior biocompatibility and facile functionalization. Regarding these features, they have been promising candidates for biomedical science and engineering applications. In this work, we reviewed the efforts made to modify these zero-dimensional nano-materials to obtain the best properties for bio-imaging, drug and gene delivery, cancer therapy, and bio-sensor applications. Five main surface modification techniques with outstanding results are investigated, including doping, surface...
Recent advances in the modification of carbon-based quantum dots for biomedical applications
, Article Materials Science and Engineering C ; Volume 120 , 2021 ; 09284931 (ISSN) ; Sedighi, O ; Tabatabaei Rezaei, N ; Abedini, A. A ; Malek Khachatourian, A ; Toprak, M. S ; Seifalian, A ; Sharif University of Technology
Elsevier Ltd
2021
Abstract
Carbon-based quantum dots (CDs) are mainly divided into two sub-groups; carbon quantum dots (CQDs) and graphene quantum dots (GQDs), which exhibit outstanding photoluminescence (PL) properties, low toxicity, superior biocompatibility and facile functionalization. Regarding these features, they have been promising candidates for biomedical science and engineering applications. In this work, we reviewed the efforts made to modify these zero-dimensional nano-materials to obtain the best properties for bio-imaging, drug and gene delivery, cancer therapy, and bio-sensor applications. Five main surface modification techniques with outstanding results are investigated, including doping, surface...
Facile and tunable method for polymeric surface modification of magnetic nanoparticles via RAFT polymerization: Preparation, characterization, and drug release properties
, Article European Polymer Journal ; Volume 167 , 2022 ; 00143057 (ISSN) ; Pourjavadi, A ; Keshavarzi, N ; Sharif University of Technology
Elsevier Ltd
2022
Abstract
Herein, the facile and tunable technique for the preparation of novel multi-stimuli-responsive nanocomposites via RAFT polymerization for DOX delivery is reported. The influence of the molecular weight of pH- and thermo-sensitive poly (acrylic acid-co-NIPAM) (PNAx), as a macro-RAFT agent, on the nanocomposites size and drug release rate was investigated. The outcome of this study reveals that macro-RAFT agent with lower molecular weight can be attached to the surface of magnetic nanoparticles with higher content of polymeric layer than can macro-RAFT agent with higher molecular weight. Also, it was observed that the particle size, polymer grafting density, DOX loading capacity, and DOX...
Supramolecular polycaprolactone nanocomposite based on functionalized hydroxyapatite
, Article Journal of Bioactive and Compatible Polymers ; Volume 27, Issue 5 , January , 2012 , Pages 467-480 ; 08839115 (ISSN) ; Shokrollahi, P ; Atai, M ; Omidian, H ; Bagheri, R ; Sharif University of Technology
SAGE
2012
Abstract
Arms bearing ureido-pyrimidinone functional groups with self-association capability (through quadruple hydrogen bonds) were successfully grafted onto hydroxyapatite nanoparticles. The supramolecularly modified nanoparticles (nHApUPy) exhibited enhanced colloidal stability compared to the original hydroxyapatite nanoparticles and were uniformly dispersed in supramolecular polycaprolactone in PCL(UPy)2/HApUPy nanocomposites at different filler loadings. The combined atomic force microscopy, mechanical, and rheological analyses confirmed a high degree of compatibility of HApUPy nanoparticles with the polymer matrix. The temperature dependence of the supramolecular structure in PCL(UPy)2/HApUPy...
Study of cemented carbonitrides with nickel as binder: Experimental investigations and computer calculations
, Article International Journal of Refractory Metals and Hard Materials ; Volume 31 , 2012 , Pages 164-170 ; 02634368 (ISSN) ; Abachi, P ; Parvin, N ; Pourazrang, K ; Sharif University of Technology
2012
Abstract
Cobalt is the most common binder in cemented carbides industry. However, there are some interests in use of alternatives. The similarity in properties has made nickel the first choice. In the present work, the effect of initial composition on modern hardmetals containing transition metal carbides/carbonitrides that are called "cemented carbonitrides" with nickel as binder was investigated. Change in quantity of additive carbides and tungsten to carbon (C/W) weight ratio through applying metallic tungsten powder in primary powder mixture had some effects on final hardness, transverse rupture strength, and microstructure of studied alloys. Addition of vanadium carbide not more than 0.2 wt.%,...
Effect of cobalt replacement by nickel on functionally graded cemented carbonitrides
, Article International Journal of Refractory Metals and Hard Materials ; Volume 30, Issue 1 , January , 2012 , Pages 42-47 ; 02634368 (ISSN) ; Abachi, P ; Pourazarang, K ; Sharif University of Technology
2012
Abstract
Functionally graded cemented carbonitrides (FGCCs) are applied in cutting tools industry. Indexable inserts made from mentioned alloys have superior cutting performance and tool life thanks the formation of a surface modified layer with enhanced properties as well as crater wear resistance. Cemented carbonitrides are made of hard carbide/nitride/carbonitride particles that have been embedded in a metallic binder. Excellent wetting ability of tungsten carbide with cobalt has made this metal the first choice as binder. However, cobalt has high cost and environmental pollution impacts. Substitution of cobalt with other metals has always been figured out. Some other metals that have been used as...
Surface chemistry of atmospheric plasma modified polycarbonate substrates
, Article Applied Surface Science ; Volume 257, Issue 23 , September , 2011 , Pages 9836-9839 ; 01694332 (ISSN) ; Taghavinia, N ; Sharif University of Technology
2011
Abstract
Surface of polycarbonate substrates were activated by atmospheric plasma torch using different gas pressure, distance from the substrates, velocity of the torch and number of treatments. The modifications were analyzed by contact angle measurements, X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM) and UV-vis spectrophotometry. Plasma treatment caused the surface characteristics to become more hydrophilic as measured by the water contact angle, which decreased from 88° to 18°. The decrease in contact angle was mainly due to oxidation of the surface groups, leading to formation of polar groups with hydrophilic property. XPS results showed an increase in the intensity of...