Simply converting color signal readout into thermal signal readout for breaking the color resolution limitation of colorimetric sensor

• Published in: Sensors and actuators. B, Chemical Chemical, 2020-04, Vol.309, p.127707, Article 127707
• Main Authors: Luo, Mingyue, Xue, Xin, Rao, Honghong, Wang, Hongqiang, Liu, Xiuhui, Zhou, Xibin, Xue, Zhonghua, Lu, Xiaoquan
• Format: Article
• Language: English
• Subjects: Alkaline phosphatase; Ascorbic acid; Colorimetric sensor; Colorimetry; Infrared lasers; Photothermal conversion; Photothermal sensor; Point-of-Care testing; Sensors; Signal readout conversion; Silver
• ISSN: 0925-4005; 1873-3077
• DOI: 10.1016/j.snb.2020.127707

•A simple strategy for converting traditional colorimetric sensor into enhanced thermometric sensors is proposed.•A color-to-thermal signal readout conversion for breaking the low color resolution of colorimetric sensor is demonstrated.•A simple and green strategy without any additions for accomplishing color-to-thermal signal readout conversion is explored.•POCT affordable detection method by facilely mixing commercial chemicals is presented. Traditional colorimetric sensors often suffer from the low color resolution and the not well-defined boundary between the yes and no answers, especially for distinguishing the similar color readouts with the naked eye. Herein, a simple strategy is communicated for greenly converting colorimetric sensor into a photothermal sensor, which is based on the simple color-to-thermal (temperature) signal readout conversion. The colorimetric system based on simply mixing commercially available chemicals of 3,3,5,5-tetramethylbenzidine (TMB) and silver ions (Ag+), provides a straightforward blue color readout owing to the generation of oxidized TMB (TMBox). In the presence of the target alkaline phosphatase (ALP), ascorbic acid phosphate (AAP) in the system could be hydrolyzed into ascorbic acid (AA), subsequently reducing the blue colored TMBox into colorless TMB. The blue-to-colorless change-based colorimetric system also exhibits the highly sensitive near-infrared (NIR) laser-driven photothermal response, allowing the successful thermometer-detectable signal-based assay for point-of-care testing (POCT) of ALP levels just using a common thermometer. This study not only demonstrated a regulatory strategy to convert color-based signal readout into thermal (temperature)-based signal readout, but also established a facile method to design affordable thermometric sensors for POCT and instrument-free bioanalysis, especially in low-resource settings.