Vitamin B1 Sensor at Neutral pH and Improvement by Cucurbit[7]uril

• Published in: Bulletin of the Chemical Society of Japan 2019, Vol.92 (9), p.1503-1508
• Main Authors: Prakash, Ramesh, Usha, Govindaraj, Karpagalakshmi, Karuppasamy, Ramalakshmi, Sundaram, Piramuthu, Lakshminarayanan, Yang, Cheng, Selvapalam, Narayanan
• Format: Article
• Language: English
• Subjects: Encapsulation; Fluorescence; Hydrogen peroxide; Nanoparticles; Organic chemistry; Oxidation; Physiology; Sensitivity; Sensors; Supramolecular compounds; Thiamine; Vitamin B
• ISSN: 0009-2673; 1348-0634
• DOI: 10.1246/bcsj.20190043

Thiamine deficiency is an important issue for many diseases and thus a facile method of detection is clinically important to improve the health of humans. For that purpose, we have developed a new thiamine sensor using starch stabilized copper nanoparticles (CSNP) at neutral pH and also improved the sensitivity of the sensor using cucurbit[7]uril (CB[7]) through host-guest chemistry. Often thiamine is not detected directly, but through the oxidation of thiamine to thiochrome (TC); TC is a fluorescent emitting molecule, through which thiamine has been measured indirectly. Here, we have demonstrated a new approach for a thiamine sensor, based on the formation of TC by the addition of hydrogen peroxide and CSNP. Unlike the other reported thiamine sensors, our method works advantageously at physiological pH conditions (pH 7, 27 °C). Furthermore, addition of CB[7] to TC, increased the sensitivity of the sensor approximately one order magnitude, through encapsulation; which can be reversed upon addition of a stronger competitive guest such as adamantylamine to confirm the encapsulation of TC. Thus, this new thiamine sensor not only performed well under physiological pH conditions, but also improved the fluorescence of TC, when encapsulated by CB[7].