Engineering of nanomaterials : Application in antibacterial activity, bio-analyte detection and environmental remediation

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PhD; 2023; Organic chemistry

Infectious diseases caused by pathogenic bacteria are creating a global health problem. In the recent report of World Health Organization (WHO), it has been mentioned that around 7 lacks people are dying each year worldwide due to drug resistant microbials. After discovery of the lifesaving “wonder drug” molecule penicillin, it was extensively used for the treatment of bacterial infection diseases. However, the excessive use of antibiotics leads to the development of antimicrobial resistance in the pathogenic bacterial strains to overcome the bactericidal effect of antibiotics. The drug-resistance bacteria follow multiple pathways to show resistance towards the existing antimicrobial agents and eventually make them abortive. The prevalence of these drug resistant bacterial strains poses a serious threat to the present medical system. Therefore, there is an urgency to develop advanced antimicrobial agents which can restrict the spread of pathogenic bacteria to eradicate infectious diseases. In this context, the current advancement in the field of nanotechnology would help us to develop nanomaterial-based antimicrobial agents which could be one of the possible alternatives of conventionally used antibiotics. There are numerous reports, which established that nanomaterials such as graphene oxide, carbon nanotube, noble metal nanoparticles, metal oxides like ZnO2, MnO2 etc. have possessed antibacterial activity. In particular, the use of nanosized molybdenum disulfide (MoS2), a transition metal dichalcogenide showed a great potential to utilize for the development of potent antibacterial agents owing to its unique chemical and photophysical properties. Two-dimensional MoS2 nanosheets provide a large surface to volume ratio for the effective interaction with the bacterial cell membrane. For better biological interactions of MoS2 nanomaterials, its surface modification can be easily achieved through functionalization using thiol ligand molecule. Functionalization also enhances its aqueous dispersibility in manyfold. In this thesis work, I have utilized MoS2 nanomaterials and their nanocomposites to develop nanomaterial-based effective antimicrobial agents for the pathogenic bacterial strains using multiple strategies. To extend my work towards the development of nanomaterial-based antibacterial agents, I have explored antibacterial activity of the supramolecularly self-assembled nanosized cage molecule to eradicate drug-resistant bacteria. Apart from antibacterial activity, I have also expanded the scope of applicability of our newly developed nanomaterials in the direction of bio-analyte detection and environmental remediation such as degradation of organic pollutant and detoxification of the chemical warfare agent.