Present disclosure provides a process for the synthesis of doped titania nanoparticle having photocatalytic activity greater than 90% at 2 hours under sunlight irradiation. The wafers are heated in greater part with a resistive heat source until a transition temperature or pressure is reached, then they are heated in greater part with a radiant heat source. The disulfide compounds according to the invention can be prepared either in vitro or in vivo and are stable in the acidic conditions of the stomach. A plurality of lights is coupled to the housing.