In this thesis, silica nanoparticles coated on different carbon dots, have been used for the delivery of anticancer drugs, as well as the optical sensor for determination pesticides. In the first study, a new strategy is reported for the synthesis of a label-free fluorescent mesoporous silica (MS) by the introduction of fluorescent carbon dots in the MSs (MSCDs) in this work. Etoposide (ETO) loaded MSCDs have been used as a drug model. Carboxymethyl ?-cyclodextrin (C?CD) used as a gatekeeper agent was attached to amine-functionalized MSCDs to retain ETO molecules inside the nanocarrier. In order to target the nanocarrier to the site of action, folic acid (FA) was grafted onto the MSCDs surface (FA-C?CD-MSCDs). The in vitro release of an entrapped ETO from the formulation in phosphate buffered saline () (pH 7.4) and citrate buffer (pH 5.4) was investigated. At neutral pH in , the pores are blocked by C?CD which prevent premature ETO release. However, under the weakly acidic intercellular environment of the tumor, the amide bond can be hydrolyzed, consequently leading to the ETO release from the nanocarrier. The targeted and ETO-loaded FA-C?CD-MSCDs showed a higher growth inhibition towards FA-positive HeLa cells compared with FA-negative HepG2 cells, as demonstrated by comparison of in vitro cytotoxicity experiments. In addition, the CDs emission was used for the fluorescent microscopic imaging. In the second study, to confirm anti-cancer activity of the palladium complex, the interaction between palladium complex and G-quadruplex DNA were investigated with multi-spectroscopic methods and molecular modeling. New folic acid-conjugated mesoporous silica nanoparticles were synthesized. The effect of calcination at 400?C on the fluorescence characteristics of mesoporous silica nanoparticles has been studied in this work. The formed carbon dots (CDs) from calcination used as the source of fluorescence. 3-Aminopropyltriethoxysilane has then been used as the amine in the surface fluorescence of mesoporous silica nanoparticles. The amine fluorescence mesoporous silica nanoparticles (amine-FM) have been coupled with folic acid (FA) as the target ligand (FA-amine-FM). A palladium complex has also been synthesized and encapsulated in the FA-amine-FM yielded fluorescent property with therapeutic effect. The in vitro release of an entrapped palladium complex from FA-amine-FM was studied under physiological conditions. According to the cell viability assay against HeLa (positive FR) and Hep-G2 (negative FR) cells, the targeted delivery system inhibited the growth of positive FR with higher selectivity compared with negative FR. Also, the emission CDs were used for fluorescence microscopic imaging. In the third study, a molecularly imprinted polymer (MIP) on silane-doped carbon dots (Si-CDs) has been synthesized as a novel optical sensor for selective detection of acetamiprid (ACT). Highly fluorescence Si-CDs have been first prepared by hydrothermal method. Subsequently, MIP has been formed on the surface of Si-CDs ( MIP@Si-CDs ) by a sol-gel process. Various parameters, which affect the optical signal, have been optimized. The fluorescence signal of MIP@Si-CDs showed linear response with ACT concentration in the 7.0-107 nM range with a detection limit of 2.0 nM. In addition, the sensor has been satisfactorily utilized for the detection of ACT content in real samples. In the fourth study, a novel optical sensor has been developed for indoxacarb (IXC) based on environmentally friendly molecularly imprinted polymer (MIP) coated on silica-carbon quantum dots (SiCQDs). Hydrothermal method was first used to prepare highly fluorescence SiCQDs on the surface of which MIP was subsequently formed ( MIP@SiCQDs ) by sol-gel method. A synergetic combination of unique characteristics of SiCQDs and the excellent selectivity of MIP was shown by the MIP@SiCQDs nanocomposites. Various parameters, which affect the optical signal, have also been optimized. A reasonable linear relationship between the fluorescence quenching effect and increased IXC concentration was found within the range of 4.0-102 nM, with a 1.0 nM detection limit and precisions of 4.5 and 2.3% for four replicate detections of 21 and 60 nM IXC, respectively, under optimal conditions. The applicability of the developed sensor for IXC detection in real samples was further verified. Good recoveries in the 95-106% range with a relative standard deviation of 6.0% were found. A fast, environmentally friendly fluorescent nanosensor detection technique using MIP@SiCQDs for successful analysis of IXC in real samples is reported in this work.