MUMBAI, India, Feb. 13 -- Intellectual Property India has published a patent application (202521132713 A) filed by Sachinkumar Gunvantrai Modha; Vidhi V. Bhopekar; and Uka Tarsadia University, Tarsadi, Gujarat, on Dec. 27, 2025, for 'multiple applications of lophine benzamide as a responsive fluorophore.'
Inventor(s) include Sachinkumar Gunvantrai Modha; Vidhi V. Bhopekar; Shiv R. Desai; and Bharvi M. Patel.
The application for the patent was published on Feb. 13, under issue no. 07/2026.
According to the abstract released by the Intellectual Property India: "The present invention relates to multiple applications of novel lophine benzamide as a responsive fluorophore. It provides methods for preparing pH-responsive hydrogels, indicator paper strips, ink and inkless writing/drawing materials, and fluorescent stamps, along with their use in information encryption and anticounterfeiting security for currency. In particular, Lophine benzamide was added to the hydrogel to produce the pH-responsive hydrogel, which shows a fluorescence change in acidic and basic pH under long UV light. Another aspect of the present invention discloses the preparation process of the pH-responsive paper strip, demonstrated by dipping it in aqueous solutions with a pH ranging from 1 to 14 and observing the fluorescence change in long UV light (365 nm). The results demonstrated that the hydrogel and paper strip exhibited properties as sensors capable of detecting acid-based solutions. Yet another aspect of the invention, Lophine benzamide, incorporated filter papers could be utilised as an inkless writing/drawing material for paper, as well as for fabric and as an inkless fluorescent stamp on paper. A Stamp/message/drawing using the said indicator solution had no colour under visible light; however, it became clearly readable under long UV due to blue emission. Dipping the same paper containing a stamp/ secret message in aqueous alkaline solution produced green fluorescence, making it unique. After dipping the pH-responsive paper up to ten times in alkaline and acidic aqueous solutions, the fluorescence reversibly changed with no loss of intensity. In yet another application, Lophine benzamide, incorporated filter papers could be utilised as a fluorescent ink writing/drawing material for paper, as well as for fabric and as a fluorescent ink stamp on paper. These fluorescent ink Stamps/messages/drawings fluoresce blue under long-wave UV light, and when exposed to alkaline aqueous solutions, the fluorescence changes to green. In still another application, lophine benzamide is utilised for information encryption and anticounterfeiting security."
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