Search or add a thesis

Advanced Search (Beta)
Home > The Structural and Optical Studies of Process Modified 1-D Nanostructures for Potential Use in Biosensing Applications

The Structural and Optical Studies of Process Modified 1-D Nanostructures for Potential Use in Biosensing Applications

Thesis Info

Access Option

External Link

Author

Mehmood, Shahid

Program

PhD

Institute

COMSATS University Islamabad

City

Islamabad

Province

Islamabad.

Country

Pakistan

Thesis Completing Year

2016

Thesis Completion Status

Completed

Subject

Physics

Language

English

Link

http://prr.hec.gov.pk/jspui/bitstream/123456789/7571/1/Shahid%20Mehmood%20FA09-PPH-008.pdf

Added

2021-02-17 19:49:13

Modified

2024-03-24 20:25:49

ARI ID

1676727596913

Asian Research Index Whatsapp Chanel
Asian Research Index Whatsapp Chanel

Join our Whatsapp Channel to get regular updates.

Similar


Integration of functionalized and modified nanostructures (NSs) in various biomedical applications has ushered significant research interests in recent years. The use of functionalized NSs in medicine and biomedical applications are vast and spans in areas such as diagnostics, drug delivery, therapy, antibiotic creams, and bioimaging, to name a few. The current scenario appeals towards surface modification of NSs, which can respond to the needs of biological problems. The main objective of the present work compiled in this thesis is to establish the effect of surface processing of one-dimensional (1-D) NSs on its structural, optical and electrochemical properties as stand alone and in a given biological media. The surface modifications of 1-D NS is performed by forming composites with metallic nanoparticles (NPs) and by post growth processing in a reduced and an oxidizing environment. Two different families of 1-D nanostructures were studied, one belonged to carbon nanotubes and other to oxide nanostructures. In the first section, a comprehensive study of the nanohybrids formed by multiwalled carbon nanotubes (MWCNTs) and metallic Au and Ag-NPs is presented. Functionalization of both –COOH bond and Au-NPs on the walls of MWCNTs has induced stresses which were observed in the X-ray diffraction patterns. The diffusion of Au-NPs in the MWCNTs was clearly observed in the high resolution TEM images, which affected the D and G Raman bands of the MWCNTs significantly. E. coli attachment has modified the local charge densities of Au-NPs-MWCNTs nanohybrids which resulted in the shift of both G and D Raman bands and increased intensity ratio of two bands. This was also reflected in the blue shift of the surface plasmon modes of the Au nanoparticles attached to MWCNTs. It was also revealed that the concentration of Ag-NPs was very vital for the antibacterial activity enhancement in Ag-NPs-MWCNTs nanohybrids. The minimal inhibitory concentration (0.5 mg/ml MWCNTs and 17.5 mg/ml Ag) of Ag-NPs-MWCNTs conjugate was also determined. The charge transfer kinetics of metallic-NPs-MWCNTs nanohybrids were also characterized by modifying the surface of glassy carbon electrode (GCE) by nanohybrids. Both the potential sweep and impedance spectroscopy demonstrated that the diffusion controlled processes were involved at the surface of modified GCE. In addition, it was revealed that the nature of the processes at the surface of nanohybrids modified GCE were quasi-reversible. The highest rate constant of 0.12 s-1 was determined as the concentration of xii Au-NPs was increased in Au-NPs-MWCNTs modified GCE. Conversely, a decreased rate constant of 0.07 s-1 was observed as the concentration of Ag-NPs on the surface of Ag-NPs- MWCNTs modified GCE increased. This suggested that the Au-NPs incorporation at higher concentration in nanohybrids have facilitated fast charge transfer mechanism and slow for Ag- NPs. Finally, nanohybrids modified GCE employed in E. coli surroundings proved that the nanohybrids were efficient for the simultaneous detection of E. coli. In second section, the effect of surface modifications of 1-D ZnO-NSs grown by the vapor–solid mechanism on its antibacterial activity was highlighted. Two sets of ZnO NSs were modified separately; first by annealing in Ar environment and second in oxygen plasma processing. Annealing in Ar resulted in a compressed lattice, which was due to removal of Zn interstitials and increased O vacancies. Plasma oxidation of the ZnO-NSs caused an expansion in the lattice due to the removal of O vacancies and incorporation of excess O, confirmed by X-ray diffraction patterns. Photoluminescence spectroscopy confirmed the surface modification of ZnO-NS, as substantial variation in intensities of visible band was observed as a result of surface modifications, which were used to quantify the Zn and O defects. The antibacterial activity of the modified ZnO-NSs demonstrated that the surface modifications by Ar annealing limited the antibacterial characteristics of ZnO-NSs against Staphylococcus aureus (S. aureus). It was then proved that the O content at the surface of the ZnO-NSs was crucial to tune the antibacterial activity against both selected gram-negative (E. coli) and gram-positive (S. aureus) bacterial species.
Loading...
Loading...

Similar Books

Loading...

Similar Chapters

Loading...

Similar News

Loading...

Similar Articles

Loading...

Similar Article Headings

Loading...

سر آغا خان

سر آغا خان
سر آغا خان کی وفات سے مسلمانوں کی ایک بڑی شخصیت اُٹھ گئی، وہ ایک اسلامی فرقہ کے امام و مذہبی پیشوا اور لاکھوں انسانوں کا مرکز عقیدت تھے، ان کی شخصیت بین الاقوامی تھی یورپ کے تمام ملکوں میں ان کا بڑا اعزاز تھا اور وہاں کے بڑے بڑے لوگوں سے ان کے دوستانہ تعلقات تھے، اس زمانہ کا کوئی بڑا سے بڑا اعزاز ایسا نہیں ہے جو ان کو حاصل نہ رہا ہو، ان کی پوری زندگی یورپ کے گہوارہ عیش و نشاط میں گزری، مگر اس میں پڑکر وہ اپنے فرائض سے کبھی غافل نہیں ہوئے۔
وہ بڑے مدبر اور بیدار مغز تھے، سیاست پر گہری نظر رکھتے تھے، علم و فن سے بھی ذوق تھا، کئی زبانوں سے واقف تھے، قومی و ملی جذبہ بھی رکھتے تھے اور مسلمانوں کے عمومی معاملات میں کبھی فرقہ کی تفریق نہیں کی، اپنے فرقہ کی فلاح و بہبود کے ساتھ عام مسلمانوں کے معاملات سے بھی دلچسپی اور عملی ہمدردی رکھتے تھے، چنانچہ مسلم یونیورسٹی کے قیام کی کوشش سے لے کر ہندوستان کی آزادی اور پاکستان کے قیام تک مسلمانوں کے بہت سے معاملات میں ان کی امداد و رہنمائی کی جس سے ان کو فائدہ پہنچا، ان کے خود نوشت حالات سے معلوم ہوتا ہے کہ دینی عقیدہ میں راسخ اور بعض مذہبی معمولات کے پابند تھے، اسلام کی تبلیغ بھی کرتے تھے اور ان کے ہاتھوں پر بہت سے غیرمسلم مشرف باسلام ہوئے، اﷲ تعالیٰ ان کے ان نیک اعمال کے صلہ میں ان کی مغفرت فرمائے، مسلمانوں میں اتنی بڑی شخصیت مدتوں میں پیدا ہوگی۔
(شاہ معین الدین ندوی، اگست ۱۹۵۷ء)

 

Detection of Metalo-Beta-Lactamase Gene in Carbapenem Resistant Pseudomonas Aeruginosa Isolated From Lahore, Pakistan Detection of Metalo-Beta-Lactamase Gene in Pseudomonas Aeruginosa

Pseudomonas aeruginosa is a widespread organism, caused severe nosocomial infection in human and associated with multiple drug resistance (MDR)Objective: The present study was carried out to observe current antimicrobial resistant pattern of Pseudomonas aeruginosa in Lahore and to detect the Metallo-beta-lactamase (MBL) gene in carbapenem resistantPseudomonas aeruginosaMethods: By screening 360 samples total 123 Pseudomonas aeruginosa was identified by standard microbiology techniques such as microscopy and biochemical testing. The isolated Pseudomonas aeruginosa was evaluated for drug resistance by disc diffusion method and polymerase chain reaction(PCR) was used to identify the carbapenem resistance causing gene (bla-VIM and bla-IMP) Results: Following antibiotic resistant pattern was observed, Gentamycin (59.00%), Ceftazidime(58.7%), Ceftriaxone (58.00%), Cefotazime (57.0%) and Ciprofloxacin (55.00%). Resistance rates to carbapenem group of antibiotics is Doripenem (30.5%) Meropenem(31.0%) and Imipenem (28.0%). Out of 123 samples of Pseudomonas aeruginosa, 28 isolates were found resistant to carbapenem group of antibiotic which was supposed to be highly sensitive for this bacterium. Molecular based identification of resistance genes showed that bla-IMP gene was present in 32.1% (09) and bla-VIM was found positive in 17.8% (04) samples. Metallo-beta-lactamasesproducing genes (bla-VIM and bla-IMP), amongcarbapenem resistant Pseudomonas aeruginosa were detectedin 28.1% of samples. If other carbapenem resistant gene were also included this number might be higherConclusions: PCRbased test should be included in routine laboratory examination for quick detection of the resistancecausing genes.

Molecular Diagnosis and Phylogeny of Infectious Bursal Disease Virus Ibdv in Chicken During Field Outbreaks in District Chakwal, Pakistan

Poultry diseases are a matter of serious concern and responsible for extremely large profit making crisis in poultry industry per anum. Outbreaks of infectious bursal disease (IBD) are continuously increasing despite vaccination in commercial broilers. The strains of IBDV currently circulating in Chakwal district broiler flocks are not known. Clinicopathologic analysis and reverse transcriptase PCR were used in 18 poultry farms which were situated in district Chakwal to confirm field outbreaks of IBD. The genetic analysis of the hypervariable part of the?VP2?gene was utilized to describe different features of total 6 isolates of these outbreaks. Arrangement of nucleotides, infer amino acid sequences through phylogenetic analysis of VP2 gene containing hypervariable part were used for dividing IBDV strains into two groups. According to phylogenetic analysis, 5 IBDV strains showed special signatures of amino acid in the VP2 gene as A222, I242, I256, I294, S299 and classified as vvIBDV.They showed 97%?99% identity at the nucleotide level. Furthermore, the sequencing analysis of detected field strains revealed the high similarity and close clustering with vvIBDV strains isolated from India, Pakistan, and China, suggesting geographic and temporal relationships among these strains. Interestingly, one IBDV strain clustered togather with vaccinal IBDV strains and representing 99% sequence likeness with vaccine strains which were dissipated, suggesting possible role of attenuated vaccines in the outbreaks of IBD. Our study revealed circulation of vvIBDV strains in Chakwal broiler flocks and these evidences emphasize the need of further detailed and more systemic approaches to evaluate IBDV diffusion and characterization to design effective control strategies.