Direct Intercalation of Bis-2,2',2 double prime ,6-terpyridylcobalt(III) into Zirconium Phosphate Layers for Biosensing Applications

• Published in: Langmuir Vol. 28; no. 9; pp. 4447 - 4452-4447-4452
• Main Authors: Santiago-Berrios, Mitk'El B, Declet-Flores, Chasterie, David, Amanda, Borrero, Solmarie, Velez, Meredith M, Diaz-Diaz, Agustin, Guadalupe, Ana R, Colon, Jorge L
• Format: Journal Article
• Language: English
• Published: 06.03.2012
• ISSN: 0743-7463; 1520-5827
• DOI: 10.1021/la2035104

The direct intercalation reaction of [Co(tpy) sub(2)] super(2+) with the highly hydrated [thetas] phase of layered zirconium phosphate ([thetas]-ZrP) resulted in the formation of the oxidized [Co(tpy) sub(2)] super(3+) ion within the ZrP material. The X-ray powder diffraction patterns showed that the interlayer distance increases from 10.3 Aa in [thetas]-ZrP to 14.9 Aa in the dry [Co(tpy) sub(2)] super(3+)-inte rcalated ZrP {[Co(tpy) sub(2)] super(3+):ZrP } phase. The complex remains electroactive within the layers of ZrP. The formal potential of a carbon paste electrode (CPE) modified with [Co(tpy) sub(2)] super(3+):ZrP (E degree ' = 40.8 mV versus Ag/AgCl, 3.5 M NaCl) is non-pH-dependent. However, the sensitivity of the [Co(tpy) sub(2)] super(3+):ZrP- modified CPE for the detection of reduced nicotinamide adenine dinucleotide (NADH) electrooxidation was lower than that of a previously reported CPE modified with [Ru(phend) sub(2)bpy] super(2+) -intercalated ZrP.(1) To improve the characteristics of NADH electrooxidation of the [Co(tpy) sub(2)] super(3+):ZrP- modified CPE, we included the enzyme diaphorase in solution, which increased the electrocatalytic current for NADH oxidation. A bienzymatic lactate biosensor was constructed and used for lactate sensing.