Responsive polymer-based gold nanoparticles are capable of altering their unique optical properties, chemical and/or physical properties upon exposure to external stimuli, which allows these materials to use in a diverse range of biomedical applications. Herein, the use of temperature responsive polymers and glycopolymers functionalised gold nanoparticles is given as sensors and biosensors, for controlled and triggered target detection. Chapter 2 investigates the transition characterisation and thermal aggregation co-operative behaviour of thermo-responsive polymer conjugated gold nanoparticles for a detailed understanding of fundamental features to apply in a biosensing system. Chapter 3 develops an optical, gold nanoparticle-based biosensor for the detection of specific biological target. Both temperature responsive and molecular recognizable polymers co-coated gold nanoparticles that change colour by protein-carbohydrate interaction mediated interparticular aggregation are controllable at desired condition. Optimisation of the particle coating is very essential to enhance the sensitivity and specificity of the biosensing system. Finally, this strategy is then extended and improved in Chapter4, with a larger glycans for probing control over the expression of particle surface glycans triggering carbohydrate-carbohydrate interactions with high specificity and selectivity, effectively. In summary, functionalised polymers and gold nanoparticles have been synthesized and developed as a biosensor. These gold nanoparticle conjugates may promise a powerful solution for rapid and reliable identification of disease and point-of-care treatment in modern healthcare issue.