Areas of Interest/Specialization:  

1. Semiconductor-Based Photocatalysis for Solar to Chemical Energy Conversion:

• The band gap of semiconductors such as CdS, TiO₂ and ZnO is suitable for absorption of visible or ultraviolet light. Upon photoexcitation, electron-hole pairs are created which can be used to initiate the redox reactions of organic molecules adsorbed on the surface of the semiconductor nanoparticles. The efficiency of the photocatalytic system can be improved by employing various strategies such as coupling two semiconductors or coupling a semiconductor with a noble metal (Ag or Au). Hence, semiconductor-based photocatalysts can effectively convert solar energy into chemical energy.

2. Interaction of Colloidal Semiconductors and Noble Metals with Biomolecules:

• Studies on the interaction of colloidal semiconductor and noble metal nanoparticles with biomolecules such as amino acids, proteins and DNA bases are useful from the viewpoint of sensing and biological labelling applications. Analytical techniques such as UV-visible, Infra-red and Fluorescence spectroscopy are useful tools for characterizing the nanoparticle-biomolecule interaction. Dynamic light scattering  technique provides information on the change in hydrodynamic size of colloidal particles upon interaction with the biomolecules.

Experience:

• Post-doctoral Fellow: Chungnam National University, Taejon, South Korea (July 2001 - June 2002)
• Assistant Professor: Department of Chemistry, NEHU (June 2003 – December 2016)
• Associate Professor: Department of Chemistry, NEHU (December 2016 – Present)

Awards 

• Received Outstanding Reviewer Award from IOP Publishing, Bristol, U.K., in 2018 for Materials Research Express.

PhD Awarded/Supervised: 5

Administrative responsibilities undertaken:

• Member, Board of Studies in Chemistry, NEHU
• Member, Board of Studies in Nanotechnology, NEHU
• Member, Board of Studies in Biotechnology, NEHU
• Member, School Board of Physical Sciences, NEHU

Academic affiliations:

• Life Member, Indian Society for Radiation and Photochemical Sciences, Mumbai
• Life Member, Indian Society for Surface Science and Technology, Kolkata

Research Projects

Investigation of Photophysical and Photocatalytic Properties of Colloidal Semiconductors: Sponsored by Department of Science and Technology, New Delhi (2006-2009).

Publications

List of Publications

• Recent developments in the colorimetric sensing of biological molecules using gold nanoparticles-based probes, D.P.S. Negi, Talanta Open, 6 (2022) 100122.
• Quenching of tryptophan fluorescence by colloidal Cu₂S nanoparticles through static and dynamic modes under different solution pH. D. Saha and D.P.S. Negi, Chem. Phys., 530 (2020) 110644.
• Particle size enlargement and 6-fold fluorescence enhancement of colloidal CdS quantum dots induced by selenious acid. D. Saha and D.P.S. Negi, Spectrochim. Acta A, 225 (2020) 117486.
• pH Dependant competitive N-de-ethylation and degradation of Rhodamine B photocatalyzed by cationic surfactant stabilized ZnS nanoparticles. W. Warjri and D.P.S. Negi, Indian J.  Chem., 58A (2019) 554-560
• Cysteine-stabilized silver nanoparticles as a colorimetric probe for the selective detection of cysteamine. S. Diamai and D.P.S. Negi, Spectrochim. Acta  A, 215 (2019) 203-208.
• Effect of pH on the interaction of hypoxanthine and guanine with colloidal ZnS nanoparticles: A spectroscopic approach. D. Saha, S. Diamai, W. Warjri and D.P.S. Negi, J. Mol. Liq., 278 (2019) 460-466.
• Catechol oxidase mimetic activity of cadmium sulfide nanoparticles for the oxidation of L-3,4 – dihydroxyphenylalanine. W. Warjri, D. Saha, S. Diamai and D.P.S. Negi, Mater. Res. Express,  6 (2019) 035020.
• Sensitive determination of 6-mercaptopurine based on the aggregation of phenylalanine-capped gold nanoparticles. S. Diamai, W. Warjri, D. Saha, D. P.S. Negi, Colloids Surf. A, 538 (2018) 593-599.
•  Spectroscopic investigations on the interaction of thioacetamide with ZnO quantum dots and application for its fluorescence sensing. D. Saha, D.P.S. Negi, Spectrochim. Acta A, 189 (2018) 516-521.
• EDTA-capped gold nanoparticles as a colorimetric probe for aluminium. S. Diamai, D.P.S. Negi, Mater. Res. Express, 3 (2016) 115002.
• Au@Co0.4S core-shell nanoparticles: synthesis, characterization and evaluation of photocatalytic activity. W. Warjri, D.P.S. Negi, Mater. Res. Express, 3 (2016) 095004.
• Synthesis of zinc sulfide nanoparticles stabilized by sodium dodecylsulfate micelles and evaluation of photocatalytic activity. L.M. Devi, D.P.S. Negi, Ind. J. Chem., 54A (2015) 1440-1445.
• Fluorescence-based selective sensing of 1,2,4-trihydroxybenzene using histidine-stabilized ZnS nanospheres. L.M. Devi, D.P.S. Negi, Mater. Res. Express, 1 (2014) 015008.
• Effect of starting pH and stabilizer/metal ion ratio on the photocatalytic activity of ZnS nanoparticles. L.M. Devi, D.P.S. Negi, Mater. Chem. Phys., 141 (2013) 797-803.
• Photophysical and photocatalytic properties of histidine-stabilized CdS quantum dots in the presence of indole. T.I. Chanu, D.P.S. Negi, Chem. Phys. Lett., 522 (2012) 62-66.
• Sensitive and selective detection of adenine using fluorescent ZnS nanoparticles. L.M. Devi, D.P.S. Negi, Nanotechnology, 22 (2011) 245502.
• Synthesis of histidine-stabilized cadmium sulfide quantum dots: Study of their fluorescence behaviour in the presence of adenine and guanine. T.I. Chanu, D.P.S. Negi, Chem. Phys. Lett., 491 (2010) 75-79.
• Surface-modified CdS nanoparticles as a fluorescent probe for the selective detection of cysteine. D.P.S. Negi, T.I. Chanu, Nanotechnology, 19 (2008) 465503.
• Photoinduced electron transfer in some photosensitive molecules-incorporated semiconductor/zeolites: New photocatalytic systems. M. Yoon and D.P.S. Negi, J. Chem. Sci.,114 (2002) 593-602.
• Photophysics and photocatalytic properties of Cd(OH)₂ –coated Q-CdS clusters in the presence of guanine and related compounds. A. Kumar and D.P.S. Negi, J. Colloid Interface Sci., 238 (2001) 310-317.
• Photophysical and photocatalytic behaviours of Cd(OH)₂ –coated Q-CdS in the presence of tryptophan. A. Kumar and D.P.S. Negi, J. Photochem. Photobiol. A, 134 (2000) 199-207.
• Photocatalytic oxidative C-C bond cleavage of the pyrrole ring in 3-methylindole induced by colloidal CdS particles. A. Kumar, S. Kumar and D.P.S. Negi, J. Chem. Res. (S), (1998) 54-55.

Academic affiliations :

• Life Member, Indian Society for Radiation and Photochemical Sciences, Mumbai
• Life Member, Indian Society for Surface Science and Technology, Kolkata

Papers presented in Conferences/Seminars

• Delivered an invited lecture entitled “Colorimetric sensing of Al³⁺ and 6-mercaptopurine using functionalized gold nanoparticles” at Third International Conference on Nanomaterials: Synthesis, Characterization and Applications, May 11-13, 2018, Mahatma Gandhi University, Kottayam, India.
• Presented a poster entitled “Photocatalytic degradation of methyl orange using sodium dodecylsulfate micelle stabilized colloidal ZnS nanoparticles” at Materials Research Society of India Symposium on Advanced Materials for Sustainable Applications, February 18-21, 2016, CSIR-NEIST, Jorhat, India.
• Delivered an invited lecture entitled “Selective sensing of 1,2,4-trihydroxybenzene in the presence of its isomers using histidine-stabilized ZnS nanospheres” at North East Regional Seminar on Trends in Colloid and Interface Science, November 27-28, 2014, NEHU, Shillong, India.
• Delivered an oral presentation entitled “Photocatalytic degradation of rhodamine B dye using histidine stabilized CdS quantum dots at International Conference on Nanoscience and Nanotechnology, March 18-20, 2013, SRM University, Kattankulathur, India.
• Delivered an invited lecture entitled “Semiconductor nanoparticles: Quantum size effect and sensing properties” at National Workshop on Emerging Trends in Nano Chemistry, September 20-21, 2011, St. Anthony’s College, Shillong, India.

Collaboration/Consultancy: 

• Collaboration with Dr. L.R. Singh, Department of Nanotechnology, NEHU, Shillong.

Any other:

Reviewer for the following Scientific Journals:

1. Sensors and Actuators B (Elsevier)
2. Analytical Methods (RSC)
3. Spectrochimica Acta A (Elsevier)
4. Materials Research Express (IOP)
5. Nanotechnology (IOP)
6. Analytica Chimica Acta (Elsevier)