PEGylated graphene oxide-based colorimetric sensor for recording temperature.

• PEG-GO-based colorimetric temperature sensing using Dz and PNA. • Complementary PNA inhibits Dz activity and color change. • PEG-GO rescues Dz activity by scavenging PNA. • Measured temperatures recorded for later visualization. • Potential applications in health diagnostics and food safety. Temperature is an essential parameter in various fields, including chemistry, biology, environmentology, industry, and medical sciences. Currently, temperature detection using practical colorimetric methods has not been sufficiently explored. In this study, we established a polyethylene glycol-functionalized graphene oxide (PEG-GO)-based colorimetric thermosensor using guanine (G)-rich DNAzyme (Dz) and peptide nucleic acid (PNA). Dz served as the template DNA for thermosensitive nanostructures and as catalytic DNA for colorimetric assays. The peroxidase-like activity of Dz was completely inhibited after hybridizing with PNA, which could be recovered in the presence of PEG-GO in a thermosensitive manner, resulting in colorimetric temperature visualization. The temperature-sensing range of this system could be simply tuned by designing a PNA strand based on the melting temperature of the Dz/PNA duplex of interest. Smartphone assistance in this colorimetric platform enabled more precise, sensitive, and practical recognition of fine temperature changes. Moreover, this design permitted recall of the target temperature, enabling the visualization of the temperature at a later point. This robust system has the potential to be a tool for rapid temperature-sensing applications, such as in health diagnostics and food safety, and it could become a valuable resource for basic and applied nanobiotechnology research. [ABSTRACT FROM AUTHOR]