Surface defective TiO2 nanoparticles by femtosecond laser modification with enhanced electron transfer rate for biosensing applications

Titanium dioxide (TiO2) has become important functional material for biosensing applications because of its low toxicity, chemical and thermal stability, chemical inertness, and biocompatibility. There are two critical aspects to improve the sensitivity of TiO2, which are enhancing the biological material adsorption and increasing the electron transfer rate. [1] They are known to be strongly dependent on surface modification. Formation of surface defects, such as the presence of Ti3+ species, oxygen vacancies, and surface disorders. Ti3+ species and oxygen vacancies generations have been very effective on electronic properties of TiO2. These defects have been produced by various techniques, however most of them require either high temperature or high-pressure reactions. [2] Pulsed laser irradiation has been introduced to get rid of the given undesired production necessities. Fig. 2a shows, the color of the TiO2 dispersions changes from white to blue-gray upon laser irradiation and  increasing the laser irradiation time darkens the colour, reaching maximum darkness after 90 minutes. Figure 4. Electrical properties of surface defective and untreated TiO2 with different channel length. • Thickness of laser surface defective TiO2and untreated TiO2 on channel are 125 nm and 50 nm, respectively.

In this study, we observed that surface defective TiO2 has enhanced conductivity and electron transfer rate than undefective TiO2.