Department of Chemistry

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Author: search.filters.author.Ayesha Khalid

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    Synthesis and Yield Optimization of Polyhydroxyalkanoates (PHA) from Sugarcane Molasses using the Bacterium Priestia Megaterium DSM 3228
    (Library Information Services, COMSATS University Islamabad, Lahore Campus, 2025) Ayesha Khalid; SP23-R06-008; Prof. Dr. Robina Farooq; LHR TP 9468
    The polyhydroxyalkanoates (PHA) act as intracellular energy storage substances in many prokaryotes. These bio-based polymers biodegradable and biocompatible. Short and medium chain length PHAs are industry produced by m icroorganisms and their enzymes . Short-chain length PHA is produced by the well-known bacterium Priestia megaterium (previously Bacillus megaterium). The goal of the study is to optimize PHA yield and improve the efficiency of the manufacturing process by examining different concentrations of carbon and nitrogen compounds . At a pH of 7 and temperature 37°C, the culture medium supplemented with 17 g/L sugarcane molasses as the carbon source and 0.05 g/L ammonium sulphate as the nitrogen source produced a maximum PHB of 0.95 g/L. The investigation has shown that FTIR can be used as an indirect method for determining the presence of PHB. The FTIR analysis confirmed the biopolymer's structure as polyhydroxybutyrate (PHB) by detecting the presence of methyl, methylene, hydroxyl, and ester carbonyl groups. Polyhydroxyalkanoates (PHA) and their monomeric components were identified using GC-MS chromatography.
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    Development of Antibacterial & Osteogenic Nanocomposite Membranes for Guided Bone Regeneration
    (Library Information Services COMSATS University Islamabad Lahore Campus, 2020-02-25) Ayesha Khalid; FA19-R06-012; Dr. Aqif Anwar Chaudhry; LHR TP 7345
    A number of treatments and modalities have been reported to fasten the process of bone regeneration including guided bone regeneration where a barrier membrane provides an isolated space and medium to the defect site to recover quickly without the intervention of surrounding soft tissues. Despite several advantages of both resorbable and non-resorbable membranes, resorbable membranes are usually preferred as they don’t need a second surgery for their removal. They also degrade easily whilst performing the required function of bone restoration. For clinical applications, gelatin/chitosan blend have warrant attention as they provide unique properties. Gelatin possesses RGD like sequences which facilitate cell attachment and migration whereas chitosan is another bioactive and degradable polymer that is widely used in many applications. High degradability, however, may lead to loss of mechanical strength. To overcome this problem, certain cross-linkers are added with the intention of increasing strength and extending the time of degradation.