LbL Film with PtNPs as a Sensor of the Dopamine Encapsulated in Liposomes

Abstract

The detection of dopamine (DA) encapsulated in liposomes prepared by the hydrating of a thin film of dipalmitoyl phosphatidylcholine (DPPC) with DA solution, was investigated using LbL films containing sulphonate p-phenylenevinylene (PPV-SO3) and the hybrid formed by incorporation platinum nanoparticles (PtNPs) in the cavities of chloride-3-n-propylpyridiniumsisesquioxane polymer (SiPy+Cl-), designed as PPV/Pt-SiPy+Cl-. The LbL films of (PPV/Pt-SiPy+Cl-)n deposited on FTO was applied as sensors to detection of free and encapsulated DA into liposomes. The LbL films with 3 bilayers (PPV/Pt-SiPy+Cl-)3 present higher current values for DA oxidation (Ipa = 76 µA) and higher separation between the oxidation potential of the DA (0.97 V) and the oxidation potential of the ascorbic acid (AA) and uric acid (UA) interferences (1.60 V) (∆pa = 630 mV). The separation of the oxidation peak potentials for DA and interferences decreases to 320 mV when the DA is encapsulated in liposome. This behavior can be explained by approximation of the liposomes to electrode surface which can influences in the interaction between the Pt-SiPy+Cl- from (PPV/Pt-SiPy+Cl-)3 LbL film and the AA and AU interferences.

Development of an Electrochemical Sensor Based on LbL Films of Pt Nanoparticles and Humic Acid

“…32 The characterization of the hybrid Pt-SiPy + Cl − can be found with more detail in the literature. 32 This approach has also been successfully explored for the detection of dopamine encapsulated in liposomes 38 and H 2 O 2 in enzymatic reactions. 39 The UV-Vis spectra of the polyelectrolytes solution, Pt-SiPy + Cl − and humic acid (0.5 g L −1 ), data not shown, are in accordance with the literature.…”