Study On The Interactions Of Polyelectrolyte And Surfactant And Cyclodextrin Supramolecular Recognition In Electrochemical Sensors

In this paper, four new electrochemical sensors for the detection of electrochemically inactive molecules have been designed based on the competitive interaction, such as electrostatic and hydrophobic interactions between polyelectrolyte and charged molecules(surfactant and dye), host-guest interaction and hydrophobic interactions between β-cyclodextrin and guest molecules(amantadine, cholesterol and dye). The developed approach also has potential applications in electrochemical methods for inactive molecules. The main context was shown below: 1. An electrochemical sensor for sodium dodecyl sulfate detection based on anion exchange using eosin Y/polyethyleneimine modified electrodePolyethyleneimine(PEI) is a hyperbranched polymer containing a large number of amino groups, having good film-forming properties. It can be easily protonated and then positively charged in the acidic solution. Based on the different binding affinity of PEI toward electrochemically active eosin Y and electrochemically inactive sodium dodecyl sulfate(SDS), a simple and effective electrochemical sensor for the detection of SDS has been designed. The stronger binding affinity of the PEI toward SDS than eosin Y results in the decrease of the redox peak current of surface confined eosin Y and provides a quantitative readout for the SDS. The proposed sensor exhibited wide linear range(1- 40 μg m L-1), high stability, good regeneration, and remarkable selectivity. A linear equation Δip = 0.23298 c + 0.19847 can be obtained. The detection limit(S/N = 3) for SDS was 0.9 μg m L-1. The method has been successfully applied to the detection of SDS in real samples with satisfactory results. 2.Cation exchange based electrochemical sensor for cetyltrimethylammonium bromide detection using acridine orange/polystyrene sulfonate systemPolystyrene sulfonate(PSS), a water-soluble anionic polyelectrolyte, is one of the mostly used polymers for the preparation of polyelectrolyte layers. Based on the different binding affinity of PSS toward electrochemically active acridine orange(AO) and electrochemically inactive cetyltrimethylammonium bromide(CTAB), a simple and effective electrochemical sensor for the detection of CTAB has been designed. The stronger binding affinity of the PSS toward CTAB than AO results in the decrease of the redox peak current of surface confined AO and provides a quantitative readout for the CTAB. The difference value of the anodic peak current showed a linear relationship with CTAB concentration in a concentration range from 0.5 to 20 μg m L-1 and a detection limit of 0.3 μg m L-1 was obtained. Because of the different binding affinities between PSS and cationic surfactants with different lengths of the alkyl chain, this method can be used to detect quaternary ammonium surfactants with similar structure. 3. A novel electrochemical sensing strategy for amantadine detection based on the competitive host-guest interaction of methylene blue/β-cyclodextrin/poly(N-acetylaniline) modified electrode.Owing to the shape selectivity of the β-cyclodextrin(β-CD) cavity, β-CD can selectively bind and recognize various organic and inorganic guest molecules in the inner cavities to form stable host-guest inclusion complexes and has been extensively applied in the field of food, chemical, biological medicine and sensor. Based on the competitive host-guest interaction of amantadine(AMD) and methylene blue(MB) with β-CD, a simple and effective electrochemical sensor for the detection of AMD has been designed. The stronger binding affinity of the β-CD toward AMD than MB results in the decrease of the redox peak current of surface confined MB and provides a quantitative readout for the AMD. A linear equation Δip= 2.73 c + 0.56 can be obtained in the AMD concentration range from 0.2 to 6 m M. A good linear correlation(R2 = 0.995) was obtained and the detection limit(S/N = 3) for AMD was 0.09 m M. The method has been successfully applied to the detection of AMD in real samples with satisfactory results.4. A non-enzymatic electrochemical detection of cholesterol based on the competitive host-guest interaction of rhodamin B/β-cyclodextrin/poly(N-acetylaniline) modified electrodeCholesterol belongs to the steroidal molecule,β-CD has a high affinity for sterols as compared to other lipids in vitro, which makes these compounds quite effective in modifying cholesterol metabolism. Based on the competitive host-guest interaction of cholesterol and rhodamin B(Rh B) with β-CD, a simple and effective electrochemical sensor for the detection of cholesterol has been designed. The stronger binding affinity of the β-CD toward cholesterol than Rh B results in the decrease of the redox peak current of surface confined Rh B and provides a quantitative readout for the cholesterol. A linear equation Δip= 0.043c- 0.163 can be obtained in the cholesterol concentration range from 20 to 150 μM. A good linear correlation(R2 = 0.991) was obtained and the detection limit(S/N = 3) for cholesterol was 8.7 μM. The method has been successfully applied to the detection of cholesterol in real samples with satisfactory results.