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Functionalized dyes and graphene quantum dots - multipurpose materials

Prof. Alok K. Ray

DAE-RRF, Bhabha Atomic Research Centre, and senior professor, HBNI, Mumbai,

Former Outstanding Scientist, and head, RIS Project, BTD Group, BARC.

Fluorescent graphene quantum dots and dyes, separately or their composites, are used as multi-purpose functional materials such as oil/organic solvent sorbent in sea water, flame retardant supercapacitor, water dispersed fire-retardant coating on fabrics, chemo-sensing, bio-imaging etc. As-prepared phosphorus functionalised GQD nanomaterial is found to exhibit transparency as well as efficient flame-retardant (FR) properties on cotton fabrics and PVC cables, which are verified by stringent flame tests such as limiting oxygen index (LOI), endurance to high heat flux (50 kW/cm2) and turbulent flame at high temperature (1400 C). The patented technology is recently transferred to a vendor for commercial uses. Further, co-functionalization of P- and N- groups on the 3-D structure of graphene helps to generate a multitasking ultra-light functionalized spongy graphene, which offers removal of intermingled spurious oil and organic solvents in sea water, as well as an excellent electrochemical characteristic for flame retardant super-capacitor applications.

In contrast, supramolecular non-covalent interactions of different dyes/GQDs with various macrocyclic hosts such as cucurbituril, cyclodextrin and biological agents like protein (BSA), nucleic acids, antibodies etc. lead to a large enhancement in fluorescent properties of the probes, and attracted attention due to their versatile applicability in different fields. For example, the interactions of LDS-798 dye with proteins produce an exceptionally intense turn-on fluorescence sensors in the far-red region for common milk allergen, β-lactoglobulin, and quantification of albumin in the blood serum.

The talk will focus on realization of functionalized graphene materials and dyes, characterization of their structure and dynamics in aqueous interface by various spectroscopy techniques towards applications.

Brief Biodata of Prof. Alok Kumar Ray

Dr. Alok K. Ray joined Laser & Plasma Technology Division, B.A.R.C., Mumbai in 1983 after M.Sc. in Chemistry from University of Kolkata and completion of 1-year BARC training school orientation course in Applied Chemistry. He has received his Ph.D. in Physics from the University of Mumbai in 1993, followed by EEC Post-doctoral fellowship at C.N.R.S., Orleans, France during 1995-1996.

Dr. Ray had carried out directed research on pulsed laser photoionization spectroscopy to obtain information on highly excited levels of atomic uranium including its Rydberg and autoionization states for exploring its isotope-selective efficient photo-ionization pathways. Further, he had carried out pioneering works in photo-physics and photo-chemistry of laser dyes towards its sustainable and efficient use in high average power dye lasers for departmental programme. He was conferred DAE technology Group award in 2012 for indigenous development of high power dye lasers. He was a visiting professor at CNRS, Orleans, France, University of Heidelberg and University of Mainz, Germany, Imperial college of London, U.K. and Moscow State University, Moscow.

He had superannuated on November 2018 from BARC as an ‘Outstanding Scientist’ and Project Head, Resonance Ionization Spectroscopy Project”, Beam Technology Development Group. Presently, he has been working as a “Raja Ramanna Fellow” in BARC, and serving as a senior professor in Chemical Sciences, Homi Bhabha National Institute, Mumbai.

Dr. Ray has published more than 100 papers in referred international journals, and obtained 2 Indian patents. Dr. Ray has transferred a few technologies to Indian companies.

His present interests include use of laser isotope separation technology for producing highly enriched stable isotopes derived radio-pharmaceuticals for theranostic applications, and novel fluorescence dyes and graphene quantum dots towards chemo-sensing and bioimaging applications.