From clean spaces to crime scenes: Exploring trace DNA recovery from titania-coated self-cleaning substrates

•TiO2-coated self-cleaning glasses are challenging substrates for trace DNA analysis.•TiO2-coated glasses, Bioclean® and SaniTise™, most likely degrade trace DNA via photocatalysis.•Rapid trace DNA sample collection reduces impact of photocatalytic DNA degradation. Titanium dioxide (titania, TiO2) is frequently used as a coating for a variety of self-cleaning products, such as antifogging vehicle mirrors, ceramic tiles, and glass windows because of its distinct physiochemical features. When exposed to light TiO2 causes photocatalytic decomposition of organic contaminants, potentially compromising DNA integrity. The impact of TiO2-coated commercial glasses, Bioclean® and SaniTise™, on trace DNA persistence, recovery, and profiling was investigated. DNA in saliva and touch samples deposited on self-cleaning glass slides exposed to indoor fluorescent light for up to seven days was more degraded than control samples indicating some degree of fluorescent light-induced photocatalytic activity of the self-cleaning surfaces. When exposed to sunlight, DNA yields from saliva and touch samples deposited on the titania-coated substrates decreased rapidly, with a corresponding increase in DNA degradation. After three days no DNA samples applied to self-cleaning glass and exposed to natural sunlight yielded STR profiles. These results suggest that the photocatalytic activation of TiO2 is the likely mechanism of action underlying the extreme DNA degradation on the Bioclean® and SaniTise™ glasses. Consequently, rapid sample collection and use may be warranted in casework scenarios involving TiO2-coated materials.