This thesis includes the synthesis and characterization cationic and non-ionic monomers and their corresponding polymers for the application bioimaging and biosensing applications. The cationic polymers were synthesized via oxidative polymerization, and their structural and optical properties were thoroughly characterized using NMR, Mass Spectroscopy, Absorbance Spectroscopy, Fluorescence Spectroscopy, Raman Spectroscopy, Dynamic Light Scattering, Zeta Potential Charge Analysis, and Quantum Yield Analysis. The homopolymers and copolymers, produced with varying ratios of 3-butoxy-4-methylthiophene (M1) and N-allyl-N-methyl-N-(3-((4-methylthiophen-3-yl)oxy)propyl)prop-2-en-1-aminium (M2) monomers, were analyzed for their performance in various applications. A significant focus of the thesis was placed on enhancing the permeability of these nanomaterials across the blood-brain barrier (BBB) for potential therapeutic uses, particularly by optimizing the structures of polymer dots (Pdots) in the nanometer range (5-30 nm). Among the synthesized polymers, P4 (1:1 ratio M1/M2) demonstrated superior performance in crossing the BBB. In addition, it is investigated the application of cationic polymers as optical probes for the detection of Candida species, especially in the context of oral health. The polymers demonstrated enhanced fluorescence and high specificity for Candida binding, showing great potential for noninvasive detection of Oral Candidiasis. The findings suggest that these cationic polymers could serve as effective diagnostic tools for the early detection of Oral Candida, offering significant promise for clinical management. The thesis presents cationic polymers and Pdots as highly effective materials for both detecting oral fungal infections and for potential biomedical applications, particularly in improving drug delivery across the blood-brain barrier.