Browsing by Author "Dr. Mian Hasnain Nawaz"

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Metal Nanoparticles Decorated Graphene Nanosheets for Estimation of Meat Spoilage
(Library Information Services, COMSATS University Islamabad, Lahore Campus, 2025) Aeyza Kashif; SP23-R06-003; Dr. Mian Hasnain Nawaz; LHR TP 9478
In this study, we presented a highly sensitive and simple fluorescent probe based on the Au/SH-GO and Perylene (PER) for detecting meat freshness. This probe is based on the selective recognition of histamine (His), a biomarker of meat spoilage. Ultraviolet visible, Fourier transform infrared (FTIR), XRD were used to characterize the material. The fluorescence spectrophotometry was employed to examine fluorescence behavior of gold nanoparticles decorated thiolated graphene oxide against histamine. Fluorescence quenching behavior of PER/Au/SH-GO was observed as it changes its form from a non-aggregated to an aggregated form when interacting with histamine. The sensor was highly sensitive as it had a relatively low limit of detection of 1.1 mM and ranged linearly from 2.5 mM to 35 mM, thus making it efficient at identifying histamine in spoiled meat. To demonstrate the selectivity of synthesized sensor, it was tested against interfering species and the result showed that it was the highly selective towards histamine. The sensor is very stable and the results are reproducible. Moreover, salts have no pronounced effect on working of sensor. Electrochemical techniques like cyclic voltammetry and electrochemical impedance spectroscopy were also studied to check electrochemical response of sensor against histamine. The probe was successfully applied to determine the freshness of chicken samples providing an efficient non-destructive tool for the on-site freshness assessment that was confirmed by Confocal Microscopy.
PEDOT-GO Nanocomposites Based Detection of DNA Fragments Resulting from UV Induced dsDNA Damage
(Library Information Services, COMSATS University Islamabad, Lahore Campus, 2025) Tahreem Zahid; CIIT/SP24-R06-016/LHR; Dr. Mian Hasnain Nawaz; LHR TP 10022
DNA oxidative damage, particularly 8-oxoguanine (8-OxoG), is a biomarker of great significance as it leads to genomic instability and diseases, so a sensitive electrochemical platform to detect 8-oxoG using a poly(3,4-ethylenedioxythiophene) (PEDOT)/reduced graphene oxide (rGO)/ZnO nanocomposite have been proposed. The density functional theory (DFT) screening of the late transition metal oxide/rGO hybrids showed ZnO to be the most reactive matrix towards 8-oxoG, which is also consistently supported by the QTAIM, MEP and IRI analysis, which shows that Zn and O are partially covalently bonded and thus provides a strong interaction with the oxidative lesion of DNA. PEDOT/rGO-ZnO film was formed through the electropolymerization and electrodeposition processes on SPE and characterized using Fourier-transform infrared spectroscopy, scanning electronic microscopy and X-ray diffraction studies, which proved the successful synthesis of an effective and uniform hybrid network. The electrochemical performance was assessed by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and differential pulse voltammetry (DPV). The partially covalent ZnO-rGO interface increases stability and charge transfer, making the PEDOT/rGO-ZnO composite a promising device in real- time on-site detection of oxidative DNA damage.
Silver Nanoparticles Based Smart Packaging Material
(Library Information Services COMSATS University Islamabad Lahore Campus, 2020-02-25) Hamna Akram; FA19-R06-035; Dr. Mian Hasnain Nawaz; LHR TP 7316
Smart packaging of food is an emerging and challenging field of research that monitor the food quality and conditions in real-time and enable consumers to recognize freshness of food. This will lead to lessen health, food loss and environmental concerns. Several smart packaging materials based upon different detection systems are available. Out of these, Colorimetric based indicators have gained center of attention owing to on- time detection based on color change. Many dyes based colorimetric indicators have been used to detect food spoilage. But in certain cases, leaching of dyes into food has let to utilize other colorimetric materials. In the present work smart packaging material as, optical indicator for chicken meat spoilage has been fabricated and its response was analyzed. The composite material as AgNPs/PANI-NFs/Chitosan spin coated on a glass slide acted as optical indicator. The AgNPs were prepared by chemical reduction method and doped-PANI-NFs by oxidative polymerization. The materials have been characterized by SEM, FTIR, UV-Vis Spectroscopy, XRD and Contact angle measurement. The colorimetric response of PANI-NFs mediated by Ag NPs towards chicken spoilage was monitored by visual color change and RGB color model. The optimized optical response of Ag NPs/PANI-NFs/ Chitosan towards spoilage was measured with 6% concentration of indicator for 2g meat at fourth day at room temperature. The colorimetric composite formed was selective for volatile amines specifically released by spoiling chicken meat. The optimization will further be confirmed by digital colorimetric instrument and fabricated material can be used at a larger scale.
Synthesis and Characterization of Fluorescent Quantum Dots as Probes to Study Radiation Induced ds-DNA Damage
(Library Information Services COMSATS University Islamabad Lahore Campus, 2020-02-17) Muhammad Hassan Ahmad; SP19-R06-007; Dr. Mian Hasnain Nawaz; LHR TP 6511
DNA is primarily a vital biomolecule that could be ambushed by both exogenous and endogenous sources of damage. Both exogenous and endogenous threats could provoke more than 105 DNA lesions spontaneously in human cells every day. The former sources come in a number of ways including, among others, ionizing radiations, ultraviolet (UV) light, thermal or hydrolysis disruption, environmental and industrial chemicals. Damages occurred by endogenous sources may come from several internal cellular processes like epigenetic modifications, hydrolysis, alkylation, nucleobase oxidation, adduct formations in bulk and errors in DNA replication by mismatch in nucleobases. Therefore, conservation of genome integrity is critical for traits inheritance to offspring and survival of any organism. Development of a rapid, sensitive and simple tool for the screening of DNA damage is the need of time. Fluorescence method is applied in a number of ways for the recognition of specific sequences of Deoxyribonucleic acid (DNA) along with Ribonucleic acid (RNA). QDS which are semiconductor nanoparticles, possess many unique structural and functional features such as nanoscale size, suitable fixity, narrow emission spectra, versatile surface modification and high specific surface area. Owing to these exceptional characteristics, these particles are used as markers, fluorescent probes and biosensors in numerous fields. The monolayered MoS2 owing small lateral size could offer novel optical properties due to their quantum confinement effect and it could act as a promising material for the development of novel optical sensors and optoelectronic devices. A highly fluorescent MoS2 QDs based FL emission sensor was formulated to study the radiation induced ds-DNA damage. The ds-DNA solution was exposed to UV radiation and ultra-sonic waves for definite period of time to induce the ds-DNA lesions. The FL emission spectra of MoS2 QDs with different concentrations of damaged ds-DNA was observed. A significant quenching in FL intensity of highly fluorescent MoS2 QDs indicated the presence of active sites in damaged ds-DNA which formed interactions with QDs and reduced the FL activity of fluorescent QDs. The excitation wavelength (260 nm) and concentration (200 μl) for QDs was optimized and used throughout the experiment process.