Browsing by Author "Umer Daood"
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- ThesisRestrictedENGINEERING SURFACE-CHARGED CARBON QUANTUM DOTS FOR ENAMEL CRYSTAL MODIFICATION AND ANTIBACTERIAL ACTION: AN IN VITRO NANOMATERIALS STUDY(IMU University, 2025)Umer DaoodObjectives: To fabricate carbon quantum dots (CQDs) and evaluate its effects on structure and crystal orientation and mechanical, and antibacterial properties of enamel. Materials and Methods: Enamel specimens of 4 mm x 4 mm x 3 mm were cut from extracted teeth. study. CQDs were prepared using ammonium citrate and sodium hydroxide solution dialysed in deionised water. After microwave reaction, Teflon tubes were left in machine for 30 minutes to cool. Enamel block specimens were divided into 4 groups (salineS, *CQD0.1%-, **CQD0.2%-, ***CQD0.3%-, and *****CQD0.5%-) in each of the treatment solutions, soaking for about 2 weeks. X-ray diffraction analysis (XRD) was performed on enamel to determine density functional theory (DFT) calculations. Transmission electron microscopy (TEM) and zeta potentials (ζ) were performed for CQDs. After modification, enamel was evaluated using Raman mapping, TEM, and Xray diffraction (XRD) analysis. Mechanical and antibacterial properties were evaluated using atomic force microscopy and TEM/SEM. For statistical analysis, null hypothesis was set at p<0.05 probability level. Results: Discrepancies in peak position between experimental and theoretical XRD diffraction patterns are due to differences in calculated parameters of ***CQD0.3%- and ***CQD0.5%- groups bringing conformational changes. Zeta potential values were least for salineS and maximum for *****CQD0.5%-. **CQD0.2%- group exhibited reduced v₁PO₄³⁻ intensity, with *****CQD0.5%- demonstrating the highest. The groups, arranged by ascending intensity, are salineS <*CQD0.1%-, <**CQD0.2%-, <***CQD0.3%-, < *****CQD0.5%-. TEM indicated spherical carbon dots with increase in enamel lattice parameter relative to the HAP unit cell in *****CQD0.5%- groups. *****CQD0.5%- group had highest elastic modulus and nano hardness. Bond length and angles show higher significant measures in CQD groups. CQD groups demonstrated higher antibacterial activities engulfing bacteria.