Tailoring the surface coordination of nitrogen doped nano titania to design -A specific fluorescence signal amplification probe for ochratoxin A detection

Metal based nanoprobes for fluorescence signal amplification have become a vital component of biosensing research due to their profound electrical, optical and sensing properties. Because of high specific surface area and photoactive reactions on the surface, nano-Titania (nTiO2) has attracted much attention in the scientific community. Titania can be modulated to be applicable in sensing designs through doping with nonmetallic elements. Thus, it is of great significant to investigate the doped counterparts of nTiO2 for biosensing applications. In this context, we herein integrated surface complexation feature of nitrogen doped nTiO2 (N-nTiO2) to contribute towards enhanced fluorescence signal amplification and subsequently employed it for ultrasensitive detection of Ochratoxin A (OTA). Results indicate that N-doping greatly influenced the surface chemistry and functionalities of nTiO2. The higher amplification efficacy of nitrogen doped nTiO2 can be attributed to its capabilities of good adsorbability and high electron mobility that substantially catalyzes the surface complexation of OTA onto these particales, consequently intensifying the fluorescence of OTA efficiently. Characterization tools including SEM, XRD, FTIR, UV–Vis, RAMAN spectroscopy, photoluminescence (PL) and flouremetric analysis were used to inspect the surface chemistry, morphology and signal amplification activity of prepared nanoprobe. Different parameters such as concentration of nano particles and incubation time were optimized for ultrasensitive detection of OTA. Under optimal experemental conditions, the limit of detection for OTA was as low as to 0.1 ng mL−1 with linear range from 0.5 to 100 ng mL−1. In conclusion, we proposed a highly sensitive and selective fluorescent nanoprobe for analytical applications based on surface complexation affinity and fluorescence signal amplification ability of N doped nTiO2.