Part 1. A voltammetric method using a surfactant didodecyldimethylammonium bromide (DDAB) film-modified electrode was developed for simultaneous measurement of various combinations of neurotransmitters and ascorbic acid. The DDAB-modified film had the positive charge and neurotransmitters(dopamine, norepinephrine, and epinephrine) existed as the positively-charged species in the neutral solution whereas AA (ascorbic acid) as a negatively-charged one. Both the cyclic voltammetry (CV) and square wave voltammetry were used for the measurement of neurotransmitters by means of the DDAB/GC-modified electrode in phosphate buffer solution of pH=6.5. Well-separated voltammetric peaks were observed for dopamine and ascorbic acid at the DDAB/GC- modified electrodes. The oxidation potential of ascorbic acid was shifted to a more positive potential due to a positive electrocatalytic activity of the DDAB/GC-modified electrode while dopamine or norepinephrine, and epinephrine were oxidized at a more positive potential due to a negative electrocatalytic activity. A chemical interaction between ascorbic acid and the oxidized dopamine-quinone (DOQ) was observed when dopamine and ascorbic acid were observed. The RRDE (rotating ring disk electrode) method was applied to study the redox reaction mechanism of dopamine and ascorbic acid. The DDAB/GC electrode resolved the voltammetric signals of the above analytes successfully. Part 2. Electrochemically active hexacyanoferrate and hexacyanoruthenate films can be directly deposited on a surfactant DDAB(didodecyldimethylammonium bromide) modified electrodes from Fe(CN)63- and Ru(CN)63- aqueous solutions. The deposited Fe(CN)63-/DDAB, Ru(CN)63-/DDAB films are stable, and show obvious electrochemical activity in aqueous solutions with various pH. An electrochemical quartz crystal microbalance and cyclic voltammetry were used to study the in situ growth of the Fe(CN)63-/DDAB and Ru(CN)64-/DDAB films films, respectively. The formal potential of Fe(CN)63-/DDAB and Ru(CN)64-/DDAB both were shifted to a more negative potential, but Fe(CN)63-/PDDA and Ru(CN)64-/PDDA (Poly(diallyldimethylammonium Chloride) films both show unobviously shift. When compare with Fe(CN)63- and Ru(CN)64- in the same pH aqueous solutions, respectively. The preparation and electrochemical properties of composite hexacyanoferrate/DDAB and hexacyanoruthenate/DDAB films were determined, and their two redox couples showed formal potentials that demonstrated a proton effect, respectively. Electrocatalytic oxidation of SO32- and electrocatalytic reduction of SO52- on hybrid films were also investigated. The electrochemical reaction of the composite film was investigated using the rotating ring-disk electrode method. Part 3. Flavin adenine dinucleotide (FAD) can be directly deposited on a surfactant DDAB(didodecyldimethylammonium bromide) modified electrodes from aqueous solutions. The deposited FAD/DDAB films are stable, and show obvious electrochemical activity in aqueous solutions with various pH. An electrochemical quartz crystal microbalance and cyclic voltammetry were used to study the in situ growth of the FAD/DDAB film. Electrocatalytic oxidation of S2O42- and electrocatalytic reduction of O2, H2O2, S2O82-, SO52-, NO2- and L-cystine on FAD/DDAB films were also investigated. Composite film of FAD, hexacyanoferrate and hexacyanoruthenate films can be directly deposited on DDAB(didodecyldimethylammonium bromide) modified electrodes from FAD, Fe(CN)63- and Ru(CN)63- mixture aqueous solutions. The deposited Composite film of FAD, hexacyanoferrate and hexacyanoruthenate films can be deposited on PDDA (Poly(diallyldimethylammonium Chloride) modified electrodes. The formal potential of FAD/DDAB, Fe(CN)63-/DDAB and Ru(CN)64-/DDAB all were shifted to a more negative potential than FAD/PDDA, Fe(CN)63-/PDDA and Ru(CN)64-/PDDA films. Electrocatalytic reduction of O2 and S2O82- and electrocatalytic oxidation of SO32- on the FAD/Fe(CN)63-/Ru(CN)64-/PDDA hybrid films were also investigated.