This dissertation has been divided into three chapters. Each chapter has its own references. The chapter 1 describes synthesis, characterization and bioassay screening of sixtytwo (62) Schiff bases of different aldehydes (ᵴƀ1-ᵴƀ55) and ciprofloxacin (cp1-cp7) with primary amines by both, conventional as well as ultrasonication methods. Thirteen Schiff bases (ᵴƀ6, ᵴƀ11, ᵴƀ17, ᵴƀ22, ᵴƀ23, ᵴƀ24, ᵴƀ28, ᵴƀ29, ϲρ3, ϲρ4, ϲρ5, ϲρ6 and ϲρ7) are new derivatives. Comparative analysis of these two methods was also carried out. The structures of all synthesized compounds were determined with the help of IR, 1H-NMR, 13C-NMR and EI-MS spectroscopy techniques. All synthesized compounds subjected to different biological activities such as Antiinflammatory activity, Insecticidal activity, Urease Inhibitory Activity, Tyrosinase Inhibitory Activity, Anti-bacterial activity, Anti-fungal activity and Anti-oxidant activity. Only eight compounds showed tyrosinase inhibitory activity in which four compounds ᵴƀ33, ᵴƀ49, ᵴƀ50 and ᵴƀ51 were found most active and the rest of four compounds ᵴƀ32, ᵴƀ34, ᵴƀ38 and ᵴƀ55 were moderately active. ϲρ is active against tyrosinase enzyme but its derivative ϲρ6 was more active. Total eight compounds were found active in urease inhibitory assay. Five compounds ᵴƀ35, ᵴƀ38, ᵴƀ41, ᵴƀ52 and ᵴƀ54 exhibited good activity and rest of three ᵴƀ33, ᵴƀ37 and ᵴƀ49 were moderately active. ϲρ and its derivative ϲρ1 and ϲρ2 were also active in urease inhibitory assay. The compounds ᵴƀ1, ᵴƀ13, ᵴƀ41 and ᵴƀ49 were found significantly active against nearly all applied bacterial strains, ϲρ and its all derivatives (ϲρ1-ϲρ7) are active against many bacterial strains. It is found that Compounds ᵴƀ1 and ᵴƀ2, ᵴƀ13, ᵴƀ38, ᵴƀ40 to ᵴƀ43 showed strong activity against various fungal strains. The synthesized compounds were also tested for anti-oxidant activity. They displayed varying % inhibition, among them ᵴƀ3, ᵴƀ6, ᵴƀ11, ᵴƀ22, ᵴƀ24, ᵴƀ29, ᵴƀ30, ᵴƀ37, ᵴƀ38, ᵴƀ43, ᵴƀ48 and ᵴƀ52 exhibited remarkable anti-oxidant activity. ϲρ, ϲρ1 and ϲρ6 also displayed anti-oxidant activity. ϲρ6 exhibited insecticidal and immunomodulatory/anti-inflammatory activity while Unfortunately, all candidates were found inactive towards both activities. The chapter 2 describes Synthesis of nanoparticles of different metals by various methods. Three types of nanoparticles were synthesized, metal, metal oxide and metal ferrite. Metal nanoparticles were synthesized by Chemical Reduction Method, (Green synthesis) by consuming Cucumis sativus, Azadirachta indica and Syzygium aromaticum aqueous extract and egg white as a source of albumin. Metal nanoparticles of Fe (INP), Ni (NNP), Cu (CNP), Zn (ZNP), Pb (LNP), Mg (MNP) and Co (CTNP) were synthesized. For the synthesis of metal ferrite Co-precipitation technique was employed, by this method CuFe2O4 (CFNP), NiFe2O4 (NFNP), CoFe2O4 (CTFNP), PbFe2O4 (LFNP), and MgFe2O4 (MFNP) nanoparticles were synthesized. For metal oxide nanoparticles Sol-Gel Synthesis (using tartaric acid as Complexing agent), Sonochemical synthesis by using Camellia sinensis extracts and by using seaweeds (Hypnea musciformis, Gracilaria, Laurencia pinnatifida and Enteromorpha intestinalis). These seaweeds were first time used to synthesize different metal nanoparticles along with sound waves. Fe3O4 (IONP), NiO (NONP), CuO (CONP), ZnO (ZONP), MgO (MONP) and PbO (LONP) metal oxides nanoparticles were prepared. UV-vis, FTIR, SEM, AFM, EDX and XRD were the characterization techniques used to confirm the synthesis, attachment of capping agent, morphology and size determination. These nanoparticles were employed to check their anti-microbial activity. These nanoparticles were also used with anti-aging / anti-bacterial cream to investigate antimicrobial and anti-oxidant activity. Some nanoparticles were also used to remove lead ion from aqueous solution by Adsorption. Chapter 3 deals about overview of biological activities and all the procedures used to find the inhibitory power of all synthesized products.