Search In this Thesis
   Search In this Thesis  
العنوان
Biological Activity of Polymer Bound Bacteriogenic Nanoparticles /
المؤلف
Ahmed, Omnia Mohammed Abdulla.
هيئة الاعداد
باحث / أمنيه محمد عبدالله احمد
مشرف / خالد زكريا البغدادي
مشرف / مصطفي محمد حسن خليل
مشرف / ميرفت إسماعيل البرهامي
مشرف / جمال عبدالعزيز مليجي
تاريخ النشر
2020.
عدد الصفحات
186 p. :
اللغة
الإنجليزية
الدرجة
الدكتوراه
التخصص
علم الأحياء الدقيقة
تاريخ الإجازة
1/1/2020
مكان الإجازة
جامعة عين شمس - كلية العلوم - الميكروبيولوجي
الفهرس
Only 14 pages are availabe for public view

from 186

from 186

Abstract

Green biosynthesis of silver and selenium nanoparticles using environmentally friendly reducing and capping agents is a recent target approached by many researches. Microorganisms are considered cost effective and benign alternative to chemical and physical methods for nanoparticles synthesis.
In this work, soil samples were collected along Ismailia Canal bay. Among 40 bacterial isolates, only 4 isolates (Ism 1, Ism 2, Ism 26 and Ism 37), showed the ability to synthesize AgNPs and SeNPs. UV-Vis spectroscopy showed characteristic peaks for nanoparticles. Bacterial isolates showed AgNPs characteristic peaks ranged between 400 and 450 nm, and for SeNPs specific peaks ranged between 200 and 300 nm.
DLS analysis was carried out to determine the size of nanoparticles. The results showed that Ism 2 and Ism 26 synthesized the smallest SeNPs and AgNPs ranged from 50 to 120 nm and 7 to 20 nm, respectively. The 2 bacterial isolates were identified by 16S rRNA gene as Bacillus tropicus Ism 2 (MK332444) and Enterobacter cloacae (KP988024) with blast identity 99% for both.
HRTEM Analysis of AgNPs demonstrated that they had spherical shaped nanoparticles with zeta potential value of -25.9 ± 4.5 mV and PDI value of 0.390. SeNPs had -30.6 ± 6.38 mV and PDI value of 0.544. These results showed high stability and electrostatic repulsion.
AgNPs showed significant high antimicrobial activity against MDR Gram positive and Gram negative bacteria at concentrations ranged from 20 to 100 µg/ml, while SeNPs showed no antimicrobial activity against all tested MDR bacteria.
Synthesis of nanocomposites showed that PS augmentation with SeNPs or AgNPs showed aggregates through the polymer film and failed to form homogenous nanocomposite films. Meanwhile, PVA and CS showed homogenous interaction with AgNPs and SeNPs through the polymer matrix.
TGA and EDX analysis showed that AgNPs formed strong bonds with PVA and CS showing higher thermal stability and more delayed thermal decomposition in comparison with pure polymer. But SeNPs did not enhance the thermal stability of PVA and CS nanocomposites. AAS analysis showed that CS polymer had higher concentrations of both AgNPs and SeNPs, than PVA polymer.
PVA-Ag nanocomposite discs significantly inhibited the tested MDR bacteria, followed by CS-Ag nanocomposites. CS pure polymer showed antimicrobial activity against MDR bacteria that was significantly enhanced by augmentation with AgNPs but not affected by the addition of SeNPs. PVA had no antimicrobial activity alone and was significantly enhanced by the addition of AgNPs but was not affected by SeNPs addition.
Antibiofilm activity of PVA and CS was significantly enhanced by augmentation of AgNPs.
Augmentation of SeNPs with PVA and CS led to lower cytotoxicity and improvement of nanocomposites biosafety.