Catalytic switch mediated by a bio-catalyst

Author interview: Rishi Ram Mahato belongs to a small town; Chakradharpur, West Singhbhum, in Jharkhand. He has completed his graduation degree from St. Xavier’s College, Ranchi. After which he joined Indian Institute of Technology (Indian School of Mines) Dhanbad for Post-graduation in 2017. He is currently pursuing Ph.D. at IISER Mohali under the supervision of Dr. Subhabrata Maiti. He is presently working on bio-catalytic systems. Apart from research, Rishi Ram is very keen to play cricket and badminton. He also likes to know about Indian History and Polity.

How would you explain your paper’s key results to the non-scientific community?

Natural catalysts or enzymes are inherently complex structures, that perform versatile functions in living systems. These enzymes are extremely specific in terms of their substrate specificity, affinity and functionality. Herein, we have developed a CTAB-capped cationic nanoparticles-based catalytic system which can be modulated for its performance by changing the number of phosphate groups (negatively charged group) in self-assembling units (AMP/ADP/ATP). As there is only one phosphate group in AMP, it interacts very loosely with the cationic surface as compared to ATP, having three phosphate groups (multiple interacting sites, so called multivalent interaction). It is like three knots which are much stronger than a single knot.

Fig. 1: Schematic diagram to show catalytic switching of nanoparticle system by applying enzyme

Due to stronger interactions of ATP with nanoparticles, the surface pH of the nanoparticles turns out to be acidic from basic while in the presence of AMP, the pH of the nanoparticles surface remain unchanged i.e. remain basic. Further, we have used these conditions to perform two different reactions, one which is favorable in acidic conditions (Hydrazone formation) and other one in basic conditions (Proton transfer, Kemp Elimination). Apart from this, we have also modulated the pH of the nanoparticles surface by using an enzyme named, Potato Apyrase in temporal manner and hence the selectivity of the nanoparticle catalytic system towards the two different reactions have been modulated. Overall, we achieve a temporal control of the system in governing the reaction preference and catalytic activity. This work will enable in designing synthetic systems with programmed chemical reaction networking ability.

What are the possible consequences of these findings for your research area?

(i) The present work shows how the nature of nanoparticles surface can be modulated upon changing the multivalency of the self-assembling units.

(ii) We also carried out the modulation of selectivity of a catalytic system towards different reactions with time in a controlled manner using an enzyme.

Here, we found that pH of a system can be changed with the help of an enzyme. We will further use these results to investigate the catalytic activity of oligomers instead of simple nucleotides.

What was the exciting moment (eureka moment) during your research?

For me, the most exciting moment was to observe the variation in pH of the surface of catalytic system by using an enzyme (Potato Apyrase), as we can use this phenomenon to control the selectivity of the system towards two different reactions with time.

What do you hope to do next?

Here, we have studied a catalytic system whose selectivity towards reactions can be altered by changing the surface pH of the system. Further, we are investigating the catalytic activity in presence of oligonucleotide sequences instead of only nucleotides, which we have reported in this work. Apart from this, we want to develop the catalytic systems which can be modulated by external stimuli such as temperature, radiations etc.

Where do you seek scientific inspiration?

Its uplifting to read books about scientific personalities and their work. Some of them are C.V. Raman, A.P.J. Abdul Kalam, H.J. Bhabha etc. Knowing about their contribution in the field of science and research in India makes me excited and instill a sense of respect towards the scientific community. I would also like to thanks my supervisor Dr. Subhabrata Maiti for keeping me updated, motivated and inspired to think about the development happening in the field of science and research. I also seek inspiration by reading journals, magazines and articles related to science.

How do you intend to help Indian science improve?

Honestly speaking, I belong to a rural family which can be considered as poor and backward at least by today’s enlightened standards. Growing up in such difficult conditions often pushes me to think about how I could be able to uplift the life standard of people around me and strengthen the society. I will encourage every potential student to step into the field of science and research which will enrich Indian science with great minds.

Apart from this, as we all know, India is a developing country; we have not sufficient facilities in a particular institution. So, I will emphasize the collaborations among Indian research community to work together to produce best out of their hard work.

Reference

Mahato R R, Sandilya E, Dasgupta B, Maiti S (2021) Dictating Catalytic Preference and Activity of a Nanoparticle by Modulating Its Multivalent Engagement. ACS Catal. 2021, 11, 14, 8504–8509.

Edited by: Anjali Mahilkar

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