Preparation Of Polydopamine Spheres-Enzyme Modified Electrodes For Analytic Applications

Polydopamine is a major pigment of naturally occurringmelanin(eumelanin).Consequently,polydopamine displays many striking properties of naturally occurring melanin inoptics, electricity, adhesion and so on, most importantly,itprocesses excellent biocompatibility.Another valuable featureof polydopamine lies in its chemical structure that incorporates lots of functional groups such as catechol, amineand imine, which can make polydopamine show more physicochemical properties and further realize the emergence of diverse hybridmaterials.With these benefits, polydopamineis not restricted to using as a coating material andhas been rapidly incorporated into a wide range of applicationsacross the biomedical science, materials sciences, energy, sensing applications and so on.And this paper centres on synthetic methods and applications in biosensing field of polydopamine spheres,the main contents can be summarized as follows:( 1) The solvent plays an important role in a given chemical reaction. Since most reactions in nature occur in the mixed-solvent systems, a comprehensive principle for solvent optimization was required. By calculating the Hansen solubility parameters(HSP) distanceRa, we designed a model experiment to explore the influence of mixed solvents on the chemical synthes is. The synthesis of polydopamine(PDA) in the water-alcohol system was chosen as model. As predicted, the welldispersed PDA spheres were obtained in selected solvents with smallerRa values.In addition,the mixed solvent withsmallerRa values gave a higher conversion of dopamine.( 2) PDA/Fe3O4 core/shell spheres were synthes ized through a simple precipitation process for the immobilization of horseradish peroxidase(HRP) to construct a practical H2O2 biosensor. The resulted H2O2 biosensor not only has the intrins ic peroxide-like activity of Fe3O4 nanoparticles(Fe3O4NPs) and the excellent biocompatibility of polydopamine(PDA) to maintain the native structure of the HRP and good conductivity of Fe3O4 NPs which can facilitate the fast electron transfer process between HRP and the electrode.( 3) A simplebiomolecule immobilization approach has been proposed to the synthesis of multifunctional GOx-Pt@PDA core-shell spheres with physical mixture. The GOx retains its bioactivity due to the excellentbiocompatibility of PDA and can communicate electrons with the electrode efficiently due to the electronic function of platinum nanoparticles. The modified electrode Nafion/GOx-Pt@PDA/GCE was fabricated to realize the direct determination of glucose.