RSC Advances. 2016 6(73): 69261-69269
TiO2 sol-embedded in electroless Ni-P coating: A novel approach for ultra-sensitive sorbitol sensor
Pranee Rattanawaleedirojna,*, Kanokwan Saengkiettiyuta, Yuttanant Boonyongmaneerata, Supin Sangsukb, Nadtinan Promphetc, Nadnudda Rodthongkuma
aMetallurgy and Materials Science Research Institute, Chulalongkorn University, Soi Chula 12, Phayathai Road, Pathumwan, Bangkok 10330 Thailand
bSchool of Agricultural Resources, Chulalongkorn University, Soi Chula 64, Phayathai Road, Pathumwan, Bangkok 10330 Thailand
cNanoscience and Technology Program, Graduate School, Chulalongkorn University, Bangkok 10330, Thailand
Ni-P-TiO2 coating was readily prepared by direct incorporating of nano-TiO2 sol into Ni-P solution followed by electroless deposition. This coating was applied as a working electrode in electrochemical sensor for the first time. The morphologies of TiO2 sol and the coated surface were well characterized by TEM, SEM and AFM. The high hydrophilicity of this surface was verified by contact angles of 40.7/41.8. Here, the appropriate amount of TiO2 within the nanocomposite was optimized (2 g/L) prior to applying as an electrode. Interestingly, the electrocatalytic activity of coating towards the oxidation of alcoholic compounds was investigated by linear sweep voltammetry. Apparently, incorporation of TiO2 into the composites substantially improved the electrocatatlytic activity of Ni-P and 2 layers of Ni-P/Ni-P-TiO2 coating provided the highest sensitivity for all analytes, especially for sorbitol. A low LOD value of 1.0 nM and a wide linear range of 2.0 nM – 0.2 mM were achieved for sorbitol. Furthermore, a high stability and high reproducibility (2.96% RSD) of this system were obtained. Owing to an ultra-high sensitivity, wide linearity, high stability, easy preparation and low cost, it might be a promising tool for early diagnosis of diabetes via sorbitol detection. (Reproduced from RSC Advances. 2016 6(73): 69261-69269)
According to the World Health Organization (WHO) report, diabetes is 1 of 10 leading causes of death. Early detection of diabetes become a crucial clinical issue since the early stage is usually treated with the highest probability of success leading to increased patient survival rate. Sorbitol increasing by polyol pathway flux in human body was recently reported as one of the critical biomarkers for diabetic neuropathy. Traditional chromatographic techniques used for sorbitol analyses are still expensive and time-consuming; hence, development of simple, rapid and sensitive sensors for the effective detection of sorbitol is highly required for early diagnosis of diabetic related diseases.
Electrochemical sensor is the most promising technology in the transition towards point-of-care diagnostics. In this work, we discovered that Ni-P/Ni-P-TiO2 coated steel can be used as a novel working electrode in an electrochemical sensor to substantially enhance the electrocatalytic property of sorbitol leading to increased detection sensitivity as illustrated in Figure 1.
Figure 1. Electrochemical detection of sorbitol based on Ni-P/Ni-P-TiO2 electrode: a potential approach for diabetes diagnosis.
Compared with Ni-P coated steel, 2 layers of Ni-P/Ni-P-TiO2 coating prepared in this study significantly enhances the sensitivity of all tested alcoholic compounds and sugars (Figure 2a). Considering about the current response signal of all analytes, Ni-P/Ni-P-TiO2 provided the highest sensitivity for sorbitol; therefore, it was further applied for sensitive sorbitol sensor. The analytical performances of this sensor were systematically investigated as shown in Figure 2b. A linearity for sorbitol was found to be 2.0 nM – 0.2 mM with a correlation coefficient (R2) of 0.9904 and a limit of detection (LOD) was found to be 1.0 NM.
Figure 2. The current response signals towards tested alcoholic compounds and sugars on Ni-P and Ni-P/Ni-P-TiO2 (a) and linear range and detection limit of this sensor for sorbitol (b).
Based on the previous clinical report, a level of 5.1 µM of sorbitol is required to effectively differentiate between normal and diabetic subjects, which verify that our obtained detection limit (1.0 nM) is sensitive enough for early diagnosis. Thus, this novel platform might be an alternative tool for diabetes diagnosis in the near future.
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This research has been supported by the Ratchadaphiseksomphot Endowment Fund 2013 of Chulalongkorn University (CU-56-494-AM).
Miss Pranee Rattanawaleedirojn
Metallurgy and Materials Science Research Institute,
Soi Chula 12, Phayathai Road, Pathumwan,
Bangkok 10330 Thailand