الفهرس 
Chapter 1: Review of literature and plan of workOnly 14 pages are availabe for public view
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Abstract
Collagen nanoparticles (collagen-NPs) are preferred to other natural and synthetic polymeric nanoparticles in a number of ways, such as appropriate biocompatibility and biodegradability, low antigenicity, a high contact surface, less toxicity and a high cationic-charge density potential due to their multiple amino groups. Collagen-NPs have applications in many medical sectors, including skin, bone, vascular grafting, nerve tissue, articular cartilage regeneration, bioscaffold insertion, and fillers for improving wound healing. It can also help with drug delivery and be incorporated for cosmetic purposes.The important results of the present study were summarized as follow:1. Eight strains (coded as NEAA-1, NEAA-J, NEAA-1F, NEAA-26, NEAA-29, NEAA-6B, NEAA-82, NEAA-U3) were assessed for their abilities for the biosynthesis of collagen-NPs using their cell-free supernatant. After incubation, white turbidity appeared as the result of collagen-NPs formation. Among these strains, 5 strains exhibited the ability to biosynthesize collagen-NPs.2. The most potent strains for maximum biosynthesis of collagen-NPs were Streptomyces strain NEAA-1 and Streptomyces strain NEAA-6B. 3. These Streptomyces strains were tested for collagen-NPs biosynthesis, as preliminary experiments, under different conditions, such as concentrations of collagen and strains cell-free supernatant, temperature, initial pH, and incubation time. The maximum biosynthesis of the collagen-NPs was 4.13 mg/mL and 5.16 mg/mL, respectively, at 35 ºC and 40 ºC for Streptomyces strain NEAA-1 and Streptomyces strain NEAA-6B. The maximum biosynthesis of the collagen-NPs was 5.24 mg/mL and 6.33 mg/mL, respectively, at 7 pH for Streptomyces strain NEAA-1 and Streptomyces strain NEAA-6B. The maximum biosynthesis of the collagen-NPs was 6.51 mg/mL and 7.42 mg/mL after 48 h for Streptomyces strain NEAA-1 and Streptomyces strain NEAA-6B, respectively.4. Based on 16S rRNA sequence analysis as well as morphological, cultural, and physiological properties, Streptomyces strain NEAA-1 was identified as Streptomyces xinghaiensis NEAA-1 and the 16S rRNA gene sequence has beendeposited under the accession number of OQ652077.1 in the Gen Bank database. Also, Streptomyces strain NEAA-6B was identified as Streptomyces plicatus NEAA-3 and the 16S rRNA gene sequence has been deposited under the accession number of OR501412.1.• In case of collagen-NPs produced by the cell-free supernatant of Streptomyces xinghaiensis NEAA-11. The GC-MS spectral analysis of the cell- free supernatant exhibited nine linear saturated fatty acids, one unsaturated fatty acid, three types of alcohols and only one aldehyde.2. Face-centered central composite design (FCCD) has been conducted to maximize collagen-NPs biosynthesis. Maximum collagen-NPs was 8.92 mg/mL under the conditions of 10 mg/mL of collagen concentration, initial pH 7, incubation time of 48 h, and a temperature of 35 ºC. The yield of collagen-NPs obtained via FCCD optimization (8.92 mg/mL) was 3.32-fold compared to the yield obtained under non-optimized conditions (2.5 mg/mL). 3. Collagen-NPs was characterized by UV-Vis absorbance, scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), Zeta-potential, Energy-dispersive X-ray (EDX) spectroscopy.