Stimuli responsive microgel containing silver nanoparticles with tunable optical and catalytic properties

2020 ◽  
Vol 92 (3) ◽  
pp. 445-459
Author(s):  
Muhammad Siddiq ◽  
Khush Bakhat ◽  
Muhammad Ajmal
Keyword(s):  
Silver Nanoparticles ◽  
Emission Intensity ◽  
Resonance Wavelength ◽  
Catalytic Performance ◽  
Basic Medium ◽  
Gravimetric Analysis ◽  
Stimuli Responsive ◽  
Scanning Calorimetry ◽  
Transmission Electron ◽  
Swelling Capacity

AbstractIn this work, poly (vinylcaprolactam-co-itaconic acid) microgel was prepared by free radical polymerization. Silver nanoparticles were prepared in synthesized microgel networks by in situ reduction of Ag+ ions, loaded in microgel from aqueous solution of AgNO3. The prepared microgel was characterized by Fourier transformation infra-red spectroscopy, UV-Visible spectroscopy, fluorescence spectroscopy, X-ray diffraction, laser light scattering, thermal gravimetric analysis, differential scanning calorimetry and transmission electron microscopy. Swelling behavior of microgel was studied as a function of temperature and pH. The microgel was found to be in swollen state at low temperature and basic medium while in collapsed state at high temperature and acidic medium. A slight decrease in swelling capacity of microgel was observed after the fabrication of silver nanoparticles. A decrease in the emission intensity and a red shift in surface plasmon resonance wavelength of silver nanoparticles was observed with pH induced swelling of microgel. Catalytic activity of the composite microgel was studied by using them as catalyst for the reduction of 4-nitrophenol, methyl orange and methylene blue. Effects of temperature and catalyst dose were also investigated. The reduction rates of 4-NP, MB and MO were found to be 0.859, 0.0528 and 0.167 min−1, respectively. The change in catalytic performance and shift in absorption maxima and emission intensity of composite microgel as a function of temperature and pH reveals that this system has potential to be used as tunable catalyst and optical sensor.

scholarly journals Enhanced Photocatalytic Activity of Cu2O Cabbage/RGO Nanocomposites under Visible Light Irradiation

Polymers ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 1712
Author(s):  
Appusamy Muthukrishnaraj ◽  
Salma Ahmed Al-Zahrani ◽  
Ahmed Al Otaibi ◽  
Semmedu Selvaraj Kalaivani ◽  
Ayyar Manikandan ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Thermo Gravimetric Analysis ◽  
Visible Region ◽  
Catalytic Performance ◽  
Precipitation Method ◽  
Gravimetric Analysis ◽  
X Ray Diffraction ◽  
X Ray ◽  
Dye Pollutants ◽  
Transmission Electron

Towards the utilization of Cu2O nanomaterial for the degradation of industrial dye pollutants such as methylene blue and methyl orange, the graphene-incorporated Cu2O nanocomposites (GCC) were developed via a precipitation method. Using Hummers method, the grapheme oxide (GO) was initially synthesized. The varying weight percentages (1–4 wt %) of GO was incorporated along with the precipitation of Cu2O catalyst. Various characterization techniques such as Fourier-transform infra-red (FT-IR), X-ray diffraction (XRD), UV–visible diffused reflectance (UV-DRS), Raman spectroscopy, thermo gravimetric analysis (TGA), energy-dispersive X-ray analysis (EDX), and electro chemical impedance (EIS) were followed for characterization. The cabbage-like morphology of the developed Cu2O and its composites were ascertained from field-emission scanning electron microscopy (FESEM) and high-resolution transmission electron microscopy (HR-TEM). In addition, the growth mechanism was also proposed. The results infer that 2 wt % GO-incorporated Cu2O composites shows the highest value of degradation efficiency (97.9% and 96.1%) for MB and MO at 160 and 220 min, respectively. Further, its catalytic performance over visible region (red shift) was also enhanced to an appreciable extent, when compared with that of other samples.

Characterisation of Hydroxyapatite/Bacterial Cellulose Nanocomposites

2009 ◽  
Vol 17 (6) ◽  
pp. 353-358 ◽  
Author(s):  
Shengnan Zhang ◽  
Guangyao Xiong ◽  
Fang He ◽  
Yuan Huang ◽  
Yulin Wang ◽  
...  
Keyword(s):  
Differential Scanning Calorimetry ◽  
Bacterial Cellulose ◽  
Photoelectron Spectroscopy ◽  
Thermo Gravimetric Analysis ◽  
Hydroxyl Groups ◽  
Gravimetric Analysis ◽  
Scanning Calorimetry ◽  
Selected Area Electron Diffraction ◽  
Transmission Electron ◽  
Cellulose Nanocomposites

A novel nanocomposite material consisting of hydroxyapatite (HAp) deposited on a phosphorylated bacterial cellulose (BC) has been synthesised via a biomimetic route. X-ray photoelectron spectroscopy (XPS) showed that phosphate groups were successfully introduced to the hydroxyl groups of BC by phosphorylation reaction to promote the growth of calcium phosphate. Transmission electron microscopy (TEM) and the corresponding selected area electron diffraction (SAED) patterns of HAp/BC demonstrated that HAp crystals wrap the surfaces of BC fibres. In this work, HAp/BC nanocomposites were studied using thermo-gravimetric analysis (TGA) and differential scanning calorimetry (DSC). The TGA result suggested that HAp/BC nanocomposite, similar to natural bone in terms of composition, contained carbonate ions, in agreement with our previous Fourier transform infrared (FTIR) spectroscopy results. Thermal behaviour differences between BC and HAp/BC were observed by differential scanning calorimetry (DSC). The thermal stability of HAp/BC obtained from DSC showed an improvement when compared to that of a pure BC sample.

scholarly journals Structural, Thermal, Morphological, Adsorption and Catalytic Properties of Poly(BPDAH-co-ODA/PPDA)-Ag/V2O5 Nanocomposites

2019 ◽  
Vol 15 (1) ◽  
pp. 155-174
Author(s):  
Govindharajan Sribala ◽  
Balakrishnan Meenarathi ◽  
Ramasamy Anbarasan
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
1H Nmr ◽  
Catalytic Reduction ◽  
Aromatic Proton ◽  
Gravimetric Analysis ◽  
Scanning Calorimetry ◽  
Transmission Electron ◽  
Ft Ir ◽  
Scanning Electron

Thermally stable polyimides (PIs) were prepared by condensation technique at 160 ºC for 5 hours in N-methylpyrrolidone (NMP) medium under N2 atmosphere both in the presence and absence of metal (Ag) and metaloxide (MO) (V2O5) nanoparticles (NPs). The synthesized polymers are characterized by Fourier Transform Infra Red (FT-IR) spectroscopy, 1H Nuclear Magnetic Resonance (1H NMR) spectroscopy, Differential Scanning Calorimetry (DSC), Thermal Gravimetric Analysis (TGA), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), Field Emission Scanning Electron Microscopy with Energy Dispersive X-Ray (FE-SEM and EDX). The FT-IR spectrum showed a peak at 1786 cm-1 corresponding to the C=O stretching of dianhydride. The aromatic proton signals appeared between 6.7 and 7.5 ppm in the 1H-NMR spectrum of the resultant PIs. The oxydianiline (ODA) based PI with Ag NP loaded system exhibited the highest Tg value. The apparent rate constant values for the adsorption and catalytic reduction of p-nitrophenol (PNP), Cr6+ and rhodamine 6G (R6G) dye were determined with the help of UV-visible spectrophotometer. Among the catalysts, the system loaded with V2O5 NP has higher kapp values. The experimental results are critically analyzed and compared with the previously available literature values. Copyright © 2020 BCREC Group. All rights reserved 

scholarly journals Preparation, Characterization and Antibacterial Efficiency of Olive Leaves Extract and Chitosan-Silver Nanoparticles using Electrochemical Method

2019 ◽  
Vol 15 ◽  
pp. 6152-6164
Author(s):  
Moustafa Tawfik Ahmed
Keyword(s):  
Silver Nanoparticles ◽  
Uv Spectroscopy ◽  
Good Alternative ◽  
Gravimetric Analysis ◽  
X Ray Diffraction ◽  
Olive Leaves ◽  
Scanning Calorimetry ◽  
Electrochemical Approach ◽  
Vis Spectroscopy ◽  
Average Size

The present work involves the improvement of chitosan-olive leaves extract and silver nanoparticles (Cs-OLE-AgNPs) using electrochemical approach followed by UV-irradiation reduction. The formation of silver nanoparticles (AgNPs) was characterized via UV–vis spectroscopy, Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), differential scanning calorimetry (DSC), EDX, thermal gravimetric analysis (TGA) and Swelling. The obtained nanoparticles average size was 36.19 nm. UV Spectroscopy show increase of peaks at 320 and 345 nm indicate the formation of a large cluster of AgNPs. Cs-OLE and Cs-OLE-AgNPs also demon started a relativity high antibacterial against both Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) bacteria. AgNPs show broadspectrum antibacterial activity at lower concentration (0.56%) and may be regarded as a good alternative therapeutic approach in the future.

Design, technological development and evaluation of stimuli-responsive chimeric nanocarriers for cancer therapy

2019 ◽  
Author(s):  
Νικόλαος Ναζίρης
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Differential Scanning Calorimetry ◽  
Technological Development ◽  
Stimuli Responsive ◽  
Scanning Calorimetry ◽  
Transmission Electron ◽  
Micro Dsc

Η επιστήμη έχει σημαντικά επιτεύγματα μέσω της Νανοτεχνολογίας, με εφαρμογές οι οποίες ξεπερνούν κατά πολύ τις δυνατότητες των συμβατικών μέσων σε πολλά επιστημονικά πεδία, συμπεριλαμβανομένης της Ιατρικής και της Φαρμακευτικής. Η Νανοϊατρική ευδοκιμεί μετά την ανάπτυξη των πρώτων νανοτεχνολογικών φαρμάκων στα τέλη του 20ου αιώνα και αναπτύχθηκε ώστε να αποτελεί μία από τις πιο υποσχόμενες προσπάθειες στον αγώνα κατά των ανθρωπίνων ασθενειών. Σε αυτό το πλαίσιο, τα λιποσώματα από καιρού αξιοποιούνται ως νανοτεχνολογικοί φορείς φαρμακομορίων και θεωρούνται ως μία από τις πιο καλώς μελετημένες πλατφόρμες για αυτόν τον σκοπό. Αυτοί οι νανοφορείς ομοιάζουν με τα κύτταρα και χαρακτηρίζονται από δομή και ιδιότητες στη μεσοκλίμακα τα οποία είναι δυναμικά, κυριαρχούμενα από το μηχανισμό και τους νόμους που διέπουν την αυτο-συναρμολόγηση. Η διαδικασία αυτή φέρει κρίσιμη σημασία για την ανάπτυξη νέων και καινοτόμων φαρμακευτικών προϊόντων, όπως και για τη νομοθετική ρύθμιση των ακολούθων “νανο-ομοειδών” φαρμάκων.Η παρούσα διδακτορική διατριβή πραγματεύεται το σύγχρονο θέμα των αποκρινόμενων σε ερεθίσματα χιμαιρικών/μικτών νανοφορέων για τη θεραπεία του καρκίνου, οι οποίοι ανήκουν στην τάξη των καινοτόμων νανοσυστημάτων μεταφοράς φαρμακομορίων για πολύπλοκες ασθένειες. Σκοπός της έρευνας ήταν ο ορθολογικός σχεδιασμός και η ανάπτυξη χιμαιρικών νανοσυστημάτων, οι οποίοι θα αποκρίνονται σε συγκεκριμένες φυσικές και φυσιολογικές συνθήκες, όπως αλλαγές στη θερμοκρασία και μεταβολές του pH, αλλά και η αξιολόγηση της συμπεριφοράς τους κατά την αυτο-συναρμολόγηση, των τελικών ιδιοτήτων τους και της in vitro και in vivo δράσης τους. Αυτά τα νανοσυστήματα αποτελούνται από δύο διαφορετικές τάξεις βιοϋλικών, ήτοι φωσφολιπίδια και αμφίφιλα δισυσταδικά συμπολυμερή και είναι υποσχόμενοι φαρμακοφορείς για τη θεραπεία διαφόρων τύπων καρκίνου, μεταφέροντας και απελευθερώνοντας θεραπευτικούς παράγοντες επιλεκτικά στο σημείο της νόσου.Τα αναλυτικά εργαλεία τα οποία χρησιμοποιήθηκαν για την αξιολόγηση των αλληλεπιδράσεων μεταξύ των βιοϋλικών και της αυτο-συναρμολογήσεώς τους συνεισφέρουν στην ανάπτυξη ποιοτικών νανοτεχνολογικών σκευασμάτων, προσφέροντας γνώση επί των ιδιοτήτων στη νανοκλίμακα αυτών των συστημάτων και της σχέσεις τους με τον τελικό νανοφορέα. Τα εργαλεία αυτά σχετίζονται με τη θερμοδυναμική, τις φυσικοχημικές ιδιότητες, τη σταθερότητα, τη μορφολογία, τη βιοφυσική και τη λειτουργικότητα και τελικώς, με τη βιολογική τοξικότητα και αποτελεσματικότητα των χιμαιρικών νανοσυστημάτων. Συγκεκριμένα, αυτά περιλαμβάνουν τη θερμική ανάλυση, όπως είναι η διαφορική θερμιδομετρία σαρώσεως (differential scanning calorimetry, DSC) ή η micro-DSC, τη σκέδαση φωτός, τεχνικές απεικονίσεως, όπως είναι η ηλεκτρονική μικροσκοπία διαπερατότητας (transmission electron microscopy, TEM) και η κρυογονική ηλεκτρονική μικροσκοπία μεταδόσεως διαπερατότητας (cryogenic TEM, cryo-TEM) και τέλος, βιολογικές δοκιμασίες, μέσω in vitro και in vivo μοντέλων. Ο πλήρης χαρακτηρισμός ενός νανοσυστήματος, όπως τα λιποσώματα, βάσει των εργαλείων αυτών, όχι μόνο συνδράμει στην ανάπτυξη καινοτόμων νανοσυστημάτων μεταφοράς φαρμακομορίων, αλλά και στην κατανόηση του ρόλου του κάθε μοριακού συστατικού του συστήματος και της διαδικασίας της αυτo-οργανώσεως στο τελικό φαρμακευτικό προϊόν.Τελικώς, η παρούσα διδακτορική έρευνα οδήγησε στην ανάπτυξη βιοσυμβατών και λειτουργικών χιμαιρικών νανοσυστημάτων, τα οποία είναι υποσχόμενα ως πλατφόρμες μεταφοράς φαρμακομορίων για καρκίνο, μέσω της αποκρινόμενης σε ερεθίσματα συμπεριφοράς τους. Η αξία της εγκαθιδρύσεως μιας λογικής για την αξιολόγηση των νανοσυστημάτων τέτοιου τύπου μέσω του συνδυασμού συγκεκριμένων και σημαντικών εργαλείων είναι επίσης εμφανής και θα προσφέρει γνώση για την περαιτέρω ανάπτυξη καινοτόμων φαρμάκων. Επιπλέον, θα συνδράμει και στη μελέτη και έγκριση των ακολούθων προϊόντων αυτών, τα οποία είναι γνωστά ως “νανο-ομοειδοί”. Τα εργαλεία αυτά αφορούν την αξιολόγηση του μηχανισμού της αυτο-συναρμολογήσεως και της σχέσης της με τις ιδιότητες, την τοξικότητα και τη λειτουργικότητα των καινοτόμων νανοσυστημάτων μεταφοράς φαρμακομορίων, με τελικό στόχο την ανάπτυξη ποιοτικών, ασφαλών και αποτελεσματικών καινοτόμων φαρμάκων για τη θεραπεία του καρκίνου.

scholarly journals Preparation of Co Nanocrystallites by Solvothermal Process and Its Catalytic Activity on the Thermal Decomposition of Ammonium Perchlorate

2010 ◽  
Vol 2010 ◽  
pp. 1-5 ◽  
Author(s):  
Shusen Zhao ◽  
Dongxu Ma
Keyword(s):  
Thermal Decomposition ◽  
Catalytic Activity ◽  
Ammonium Perchlorate ◽  
Catalytic Performance ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Selected Area Electron Diffraction ◽  
Transmission Electron ◽  
Polyol Medium ◽  
Decomposition Behavior

Nanometer cobalt ferrite (Co) was synthesized by polyol-medium solvothermal method and characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), and selected area electron diffraction (SAED). Further, the catalytic activity and kinetic parameters of Co nanocrystallites on the thermal decomposition behavior of ammonium perchlorate (AP) have been investigated by thermogravimetry and differential scanning calorimetry analysis (TG-DSC). The results imply that the catalytic performance of Co nanocrystallites is significant and the decrease in the activation energy and the increase in the rate constant for AP further confirm the enhancement in catalytic activity of Co nanocrystallites. A mechanism based on an proton transfer process has also been proposed for AP in the presence of Co nanocrystallites.

Fabrication of Magnetic Cenosphere Deposited with Fe3O4 Nanoparticles by Hydrothermal Method

2013 ◽  
Vol 750-752 ◽  
pp. 2021-2025 ◽  
Author(s):  
Hui Zhang ◽  
Jie Yao Song ◽  
Jian Chao Zhan
Keyword(s):  
Electron Microscope ◽  
Spinel Phase ◽  
Gravimetric Analysis ◽  
Vibrating Sample Magnetometer ◽  
Hydrothermal Conditions ◽  
Scanning Calorimetry ◽  
Transmission Electron ◽  
Reaction Solution ◽  
Average Size ◽  
Thermal Stability Of

We prepared the magnetic cenospheres deposited with magnetite Fe3O4nanoparticles under hydrothermal conditions. The crystalline phase, magnetization properties, morphology, chemical composition and thermal stability of asobtained cenospheres are analyzed by Xray diffraction, vibrating sample magnetometer, scanning electron microscope, Xray energy dispersive spectroscope, transmission electron microscope, thermal gravimetric analysis and differential scanning calorimetry techniques. The results show that the inverse cubic spinel phase of Fe3O4nanoparticles with an average size 50 nm are synthesized, and synchronously deposited on cenosphere surface. As the thickness of Fe3O4coating increases, the saturation magnetization increases to some extent. The growth of Fe3O4nanoparticles can be controlled by adding ethanol to the reaction solution.

scholarly journals The Effect of Ultrasonic Treatment on Thermal Stability of the Cured Epoxy/Layered Silicate Nanocomposite

2012 ◽  
Vol 2012 ◽  
pp. 1-5 ◽  
Author(s):  
N. Y. Yuhana ◽  
S. Ahmad ◽  
A. R. Shamsul Bahri
Keyword(s):  
Thermal Stability ◽  
Ultrasonic Treatment ◽  
Binary Systems ◽  
Layered Silicate ◽  
Gravimetric Analysis ◽  
Scanning Calorimetry ◽  
Mechanical Stirring ◽  
Transmission Electron ◽  
Cloisite 30B ◽  
Thermal Stability Of

The effect of ultrasonic treatment on thermal stability of binary systems containing epoxy and organic chemically modified montmorillonite (Cloisite 30B) was studied. Differential scanning calorimetry (DSC), thermal gravimetric analysis (TGA), transmission electron microscopy (TEM), and wide angle X-ray diffraction (WAXD) analysis were utilized. The mixing of epoxy and Cloisite 30B nanocomposites was performed by mechanical stirring, followed by 1 or 3-hour ultrasonic treatment, and polyetheramine as the curing agent. Both XRD and TEM analyses confirmed that the intercalation of Cloisite 30B was achieved. Thed0spacings for silicate in cured sample prepared at 1- and 3-hour duration of ultrasonic treatment were about 21 and 18 Å, respectively. This shows that shorter duration or ultrasonic treatment may be preferable to achieve higherd0spacing of clay. This may be attributed to the increase in viscosity as homopolymerization process occurred, which restricts silicate dispersion. The 1-hour sonicated samples seem to be more thermally stable during the glass transition, but less stable during thermal decomposition process.

Effect of pH on the Green Synthesis of Silver Nanoparticles through Reduction with Pistiastratiotes L. Extract

2015 ◽  
Vol 1131 ◽  
pp. 223-226 ◽  
Author(s):  
Pranlekha Traiwatcharanon ◽  
Kriengkri Timsorn ◽  
Chatchawal Wongchoosuk
Keyword(s):  
Silver Nanoparticles ◽  
Green Synthesis ◽  
Spherical Shape ◽  
Silver Ions ◽  
Basic Medium ◽  
Metallic Silver ◽  
Visible Spectroscopy ◽  
Ag Nps ◽  
Transmission Electron ◽  
Effects Of Ph

In this work, we have presented the green synthesis of silver nanoparticles (Ag-NPs) using extracts of Pistiastratiotes L. as reducing agent. The silver nitrate (AgNO3) solutions were used as precursor. The experiments were performed under irradiation with a light that can help to increase the activation for reduction of silver ions (Ag+) to metallic silver (Ag0). The effects of pH on the nature of Ag-NPs have been systematically studied by using ultraviolet-visible spectroscopy (UV-Vis) and transmission electron microscopy (TEM). The results show that the synthesis of Ag-NPs in acidic medium gives smaller size than that in basic medium. A number of synthesized Ag-NPs increase with increasing the concentrations of acidic/basic medium. All synthesized Ag-NPs have spherical shape.

Preparation of Organic/Inorganic Nanocomposites with Microwave Process

2006 ◽  
Vol 317-318 ◽  
pp. 669-672 ◽  
Author(s):  
D.H. Kim ◽  
Seong Soo Park ◽  
B.S. Jun ◽  
Jong Kook Lee ◽  
Kyu Hong Hwang ◽  
...  
Keyword(s):  
In Situ Polymerization ◽  
Layered Silicate ◽  
Clay Content ◽  
Gravimetric Analysis ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Transmission Electron ◽  
Inorganic Nanocomposites ◽  
Microwave Process

Polymer/layered silicate nanocomposities were prepared by in situ polymerization with microwave process. The influence of the amount of clay on the structure and thermal properties for the synthesized nanocomposites were characterized by means of X-ray diffraction (XRD), transmission electron microscopy (TEM), differential scanning calorimetry (DSC), and thermal gravimetric analysis (TGA). It was found that the structure of nanocomposites, an intercalated/exfoliated structure, depended on the clay content.

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