1
|
Shandilya E, Rallabandi B, Maiti S. In situ enzymatic control of colloidal phoresis and catalysis through hydrolysis of ATP. Nat Commun 2024; 15:3603. [PMID: 38684662 PMCID: PMC11059368 DOI: 10.1038/s41467-024-47912-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2023] [Accepted: 04/16/2024] [Indexed: 05/02/2024] Open
Abstract
The ability to sense chemical gradients and respond with directional motility and chemical activity is a defining feature of complex living systems. There is a strong interest among scientists to design synthetic systems that emulate these properties. Here, we realize and control such behaviors in a synthetic system by tailoring multivalent interactions of adenosine nucleotides with catalytic microbeads. We first show that multivalent interactions of the bead with gradients of adenosine mono-, di- and trinucleotides (AM/D/TP) control both the phoretic motion and a proton-transfer catalytic reaction, and find that both effects are diminished greatly with increasing valence of phosphates. We exploit this behavior by using enzymatic hydrolysis of ATP to AMP, which downregulates multivalent interactivity in situ. This produces a sudden increase in transport of the catalytic microbeads (a phoretic jump), which is accompanied by increased catalytic activity. Finally, we show how this enzymatic activity can be systematically tuned, leading to simultaneous in situ spatial and temporal control of the location of the microbeads, as well as the products of the reaction that they catalyze. These findings open up new avenues for utilizing multivalent interaction-mediated programming of complex chemo-mechanical behaviors into active systems.
Collapse
Affiliation(s)
- Ekta Shandilya
- Department of Chemical Sciences, Indian Institute of Science Education and Research (IISER), Mohali, Knowledge City, Manauli, 140306, India
| | - Bhargav Rallabandi
- Department of Mechanical Engineering, University of California, Riverside, CA, 92521, USA.
| | - Subhabrata Maiti
- Department of Chemical Sciences, Indian Institute of Science Education and Research (IISER), Mohali, Knowledge City, Manauli, 140306, India.
| |
Collapse
|
2
|
Shandilya E, Bains AS, Maiti S. Enzyme-Mediated Temporal Control over the Conformational Disposition of a Condensed Protein in Macromolecular Crowded Media. J Phys Chem B 2023; 127:10508-10517. [PMID: 38052045 DOI: 10.1021/acs.jpcb.3c07074] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/07/2023]
Abstract
Temporal regulation between input and output signals is one of the hallmarks of complex biological processes. Herein, we report that the conformational disposition of a protein in macromolecularly crowded media can be controlled with time using enzymes. First, we demonstrate the pH dependence of bovine serum albumin (BSA) condensation and conformational alteration in the presence of poly(ethylene glycol) as a crowder. However, by exploiting the strength of pH-modulatory enzymatic reactions (glucose oxidase and urease), the conversion time between the condensed and free forms can be tuned. Additionally, we demonstrate that the trapping of intermediate states with respect to the overall system at a particular α-helix or β-sheet composition and rotational mobility can be possible simply by altering the substrate concentration. Finally, we show that the intrinsic catalytic ability of BSA toward the Kemp elimination (KE) reaction is inhibited in the aggregated form but regained in the free form. In fact, the rate of KE reaction can also be actuated enzymatically in a temporal fashion, therefore demonstrating the programmability of a cascade of biochemical events in crowded media.
Collapse
Affiliation(s)
- Ekta Shandilya
- Department of Chemical Sciences, Indian Institute of Science Education and Research (IISER) Mohali, Knowledge City, Manauli 140306, India
| | - Arshdeep Singh Bains
- Department of Chemical Sciences, Indian Institute of Science Education and Research (IISER) Mohali, Knowledge City, Manauli 140306, India
| | - Subhabrata Maiti
- Department of Chemical Sciences, Indian Institute of Science Education and Research (IISER) Mohali, Knowledge City, Manauli 140306, India
| |
Collapse
|
3
|
Priyanka, Maiti S. Co-assembly-mediated biosupramolecular catalysis: thermodynamic insights into nucleobase specific (oligo)nucleotide attachment and cleavage. J Mater Chem B 2023; 11:10383-10394. [PMID: 37874292 DOI: 10.1039/d3tb01747h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2023]
Abstract
Gaining control over the stability and cleavage of phosphoester and phosphodiester remains a matter of interest for their application in biotechnology to oligonucleotide-based therapeutics. Herein, we report an efficient unactivated phosphoester hydrolysis (stable mono/di/tri/cyclic nucleotide to nucleoside conversion) via a biosupramolecular system comprising of a non-covalent complex of enzyme, alkaline phosphatase (ALP), and Zn(II)-metallosurfactant. We also demonstrate the nucleobase selective activation or inhibition of ALP-mediated oligonucleotide digestion process using that complex. The higher binding affinity of Zn(II)-containing headgroup with phosphate-containing substrate enhanced the effective substrate concentration surrounding the enzyme, which, in turn, results in a drastic decrease in the Michaelis constant (KM), along with an increase in the turnover (kcat). The catalytic activation or inhibition of nucleobase-specific oligonucleotide digestion depends on the hydration, localization of the substrates, and viscosity of the resultant co-assembly upon substrate binding with the enzyme-metallosurfactant complex. Additionally, through isothermal titration calorimetry experiment, we demonstrate enthalpy-entropy change during both the supramolecular binding of (oligo)nucleotides and simultaneous activation/inhibition in catalytic cleavage. Overall, it showed the possible modularity of Zn(II)-mediated biosupramolecular interaction, describing intrinsic thermodynamic aspects in developing complex biocatalytic circuits with nucleobase-specific oligonucleotides inputs, which are relevant in designing nucleic acid-based cargo for drug delivery and bioimaging.
Collapse
Affiliation(s)
- Priyanka
- Department of Chemical Sciences, Indian Institute of Science Education and Research (IISER) Mohali, Knowledge City, Manauli 140306, India.
| | - Subhabrata Maiti
- Department of Chemical Sciences, Indian Institute of Science Education and Research (IISER) Mohali, Knowledge City, Manauli 140306, India.
| |
Collapse
|
4
|
Mahato RR, Juneja S, Maiti S. Benchmarking Cationic Monolayer Protected Nanoparticles and Micelles for Phosphate-Mediated and Nucleotide-Selective Proton Transfer Catalysis. Chem Asian J 2023; 18:e202300657. [PMID: 37639220 DOI: 10.1002/asia.202300657] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2023] [Revised: 08/27/2023] [Accepted: 08/28/2023] [Indexed: 08/29/2023]
Abstract
Both micelles and self-assembled monolayer (SAM)-protected nanoparticles are capable of efficiently hosting water-immiscible substrates to carry out organic reactions in aqueous media. Herein, we have analyzed the different catalytic effect of SAM-protected cationic nanoparticles and cationic surfactants of varying chain length towards base-catalyzed proton transfer mediated ring-opening reaction of 5-nitrobenzisoxazole (NBI) (also known as Kemp Elimination (KE) reaction). We use inorganic phosphate ion or different nucleotide (phosphate-ligated different nucleoside) as base to promote the reaction on micellar or nanoparticle interface. We find almost 2-3 orders of magnitude higher concentration of surfactants of comparable hydrophobicity required to reach the similar activity which attained by low cationic head group concentration bound on nanoparticle. Additionally, at low concentration of nanoparticle-bound surfactant or with high surfactant in micellar form, nucleotide-selectivity has been observed in activating KE reaction unlike free surfactant at low concentration. Finally, we showed enzyme-mediated nucleotide hydrolysis to generate phosphate ion which in situ upregulate the KE activity much more in GNP-based system compared to CTAB. Notably, we show a reasonable superiority of SAM-protected nanoparticles in activating chemical reaction in micromolar concentration of headgroup which certainly boost up application of SAM-based nanoparticles not only for selective recognition but also as eco-friendly catalyst.
Collapse
Affiliation(s)
- Rishi Ram Mahato
- Department of Chemical Sciences, Indian Institute of Science Education and Research (IISER) Mohali, Knowledge City, Manauli, 140306, India
| | - Sakshi Juneja
- Department of Chemical Sciences, Indian Institute of Science Education and Research (IISER) Mohali, Knowledge City, Manauli, 140306, India
| | - Subhabrata Maiti
- Department of Chemical Sciences, Indian Institute of Science Education and Research (IISER) Mohali, Knowledge City, Manauli, 140306, India
| |
Collapse
|
5
|
Kamra A, Das S, Bhatt P, Solra M, Maity T, Rana S. A transient vesicular glue for amplification and temporal regulation of biocatalytic reaction networks. Chem Sci 2023; 14:9267-9282. [PMID: 37712020 PMCID: PMC10498679 DOI: 10.1039/d3sc00195d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2023] [Accepted: 07/27/2023] [Indexed: 09/16/2023] Open
Abstract
Regulation of enzyme activity and biocatalytic cascades on compartmentalized cellular components is key to the adaptation of cellular processes such as signal transduction and metabolism in response to varying external conditions. Synthetic molecular glues have enabled enzyme inhibition and regulation of protein-protein interactions. So far, all the molecular glue systems based on covalent interactions operated under steady-state conditions. To emulate dynamic biological processes under dissipative conditions, we introduce herein a transient supramolecular glue with a controllable lifetime. The transient system uses multivalent supramolecular interactions between guanidinium group-bearing surfactants and adenosine triphosphate (ATP), resulting in bilayer vesicle structures. Unlike the conventional chemical agents for dissipative assemblies, ATP here plays the dual role of providing a structural component for the assembly as well as presenting active functional groups to "glue" enzymes on the surface. While gluing of the enzymes on the vesicles achieves augmented catalysis, oscillation of ATP concentration allows temporal control of the catalytic activities similar to the dissipative cellular nanoreactors. We further demonstrate temporal upregulation and control of complex biocatalytic reaction networks on the vesicles. Altogether, the temporal activation of biocatalytic cascades on the dissipative vesicular glue presents an adaptable and dynamic system emulating heterogeneous cellular processes, opening up avenues for effective protocell construction and therapeutic interventions.
Collapse
Affiliation(s)
- Alisha Kamra
- Materials Research Centre, Indian Institute of Science C.V. Raman Road Bangalore 560012 Karnataka India +9180-22932914
| | - Sourav Das
- Materials Research Centre, Indian Institute of Science C.V. Raman Road Bangalore 560012 Karnataka India +9180-22932914
| | - Preeti Bhatt
- Materials Research Centre, Indian Institute of Science C.V. Raman Road Bangalore 560012 Karnataka India +9180-22932914
| | - Manju Solra
- Materials Research Centre, Indian Institute of Science C.V. Raman Road Bangalore 560012 Karnataka India +9180-22932914
| | - Tanmoy Maity
- Materials Research Centre, Indian Institute of Science C.V. Raman Road Bangalore 560012 Karnataka India +9180-22932914
| | - Subinoy Rana
- Materials Research Centre, Indian Institute of Science C.V. Raman Road Bangalore 560012 Karnataka India +9180-22932914
| |
Collapse
|
6
|
Maiti S. Simultaneous quantification of serum albumin and gamma globulin using Zn(II)-metallosurfactant via a coffee ring pattern. Chem Commun (Camb) 2023; 59:6536-6539. [PMID: 37161733 DOI: 10.1039/d3cc01221b] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
Herein, we report interactivity and conjugate formation ability between a Zn(II)-metallosurfactant and two clinically relevant serum proteins, albumin (ALB) and γ-globulin (GGB). We found that the surfactant-ALB conjugate promotes coffee ring formation, whereas with GGB it gets suppressed, which is due to the difference in structural anisotropy and hydrophobicity of the conjugates. Additionally, validation of this biosensing platform has been established in human serum samples, and it has potential applications for on-spot rapid diagnostics in remote areas.
Collapse
Affiliation(s)
- Subhabrata Maiti
- Department of Chemical Sciences, Indian Institute of Science Education and Research (IISER) Mohali, Knowledge City, Manauli 140306, India.
| |
Collapse
|
7
|
Mahato RR, Shandilya E, Not Applicable S, Maiti S. Regulating Spatial Localization and Reactivity Biasness of DNAzymes by Metal Ions and Oligonucleotides. Chembiochem 2022; 23:e202200154. [PMID: 35762518 DOI: 10.1002/cbic.202200154] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2022] [Revised: 06/08/2022] [Indexed: 11/09/2022]
Abstract
Chemical gradient sensing behavior of catalytically active colloids and enzymes is an area of immense interest owing to their importance in understanding fundamental spatiotemporal complexity pattern in living systems and designing of dynamic materials. Herein, we have shown peroxidase activity of DNAzyme (G-quadruplex-hemin complex tagged in a micron-sized glass bead) can be modulated by metal ions and metal ion-binding oligonucleotides. Next we demonstrated both experimentally and theoretically that the localization and product formation ability of the DNAzyme containing particle remains biased to the more catalytically active zone where concentration of metal ion (Hg2+) inhibitor is low. Interestingly, this biased localization can be broken by introduction of Hg2+ binding oligonucleotide in the system. Additionally, macroscopically asymmetric catalytic product distributed zone has also been achieved on this process, showing possibility in regulation in autonomous spatially controlled chemical process. This demonstration of autonomous modulation of the localization pattern and spatially specific enhanced product forming ability of DNAzymes will further enable in designing of responsive nucleic acid-based motile materials and surfaces.
Collapse
Affiliation(s)
- Rishi Ram Mahato
- Indian Institute of Science Education and Research Mohali, Chemical Sciences, INDIA
| | - Ekta Shandilya
- Indian Institute of Science Education and Research Mohali, Chemical Sciences, INDIA
| | | | - Subhabrata Maiti
- Indian Institute of Science Education and Research Mohali, Chemical Sciences, Knowledge City, Sector-81, S.A.S. Nagar, Manauli P.O., 140306, Mohali, INDIA
| |
Collapse
|
8
|
A Hypothesis on How the Azolla Symbiosis Mitigates Nitrous Oxide Based on In Silico Analyses. J 2022. [DOI: 10.3390/j5010013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Nitrous oxide is a long-lived greenhouse gas that exists for 114 years in the atmosphere and is 298-fold more potent than carbon dioxide in its global warming potential. Two recent studies showcased the utility of Azolla plants for a lesser footprint in nitrous oxide production from urea and other supplements to the irrigated ecosystem, which mandates exploration since there is still no clear solution to nitrous oxide in paddy fields or in other ecosystems. Here, we propose a solution based on the evolution of a single cytochrome oxidase subunit II protein (WP_013192178.1) from the cyanobiont Trichormus azollae that we hypothesize to be able to quench nitrous oxide. First, we draw attention to a domain in the candidate protein that is emerging as a sensory periplasmic Y_Y_Y domain that is inferred to bind nitrous oxide. Secondly, we draw the phylogeny of the candidate protein showcasing the poor bootstrap support of its position in the wider clade showcasing its deviation from the core function. Thirdly, we show that the NtcA protein, the apical N-effecting transcription factor, can putatively bind to a promoter sequence of the gene coding for the candidate protein (WP_013192178.1), suggesting a function associated with heterocysts and N-metabolism. Our fourth point involves a string of histidines at the C-terminal extremity of the WP_013192178.1 protein that is missing on all other T. azollae cytochrome oxidase subunit II counterparts, suggesting that such histidines are perhaps involved in forming a Cu center. As the fifth point, we showcase a unique glycine-183 in a lengthy linker region containing multiple glycines that is absent in all proximal Nostocales cyanobacteria, which we predict to be a DNA binding residue. We propose a mechanism of action for the WP_013192178.1 protein based on our in silico analyses. In total, we hypothesize the incomplete and rapid conversion of a likely heterocystous cytochrome oxidase subunit II protein to an emerging nitrous oxide sensing/quenching subunit based on bioinformatics analyses and past literature, which can have repercussions to climate change and consequently, future human life.
Collapse
|
9
|
Mahato RR, Shandilya E, Maiti S. Perpetuating enzymatically-induced spatiotemporal pH and catalytic heterogeneity of a hydrogel by nanoparticles. Chem Sci 2022; 13:8557-8566. [PMID: 35974757 PMCID: PMC9337733 DOI: 10.1039/d2sc02317b] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2022] [Accepted: 06/20/2022] [Indexed: 11/22/2022] Open
Abstract
The attainment of spatiotemporally inhomogeneous chemical and physical properties within a system is gaining attention across disciplines due to the resemblance to environmental and biological heterogeneity. Notably, the origin of natural pH gradients and how they have been incorporated in cellular systems is one of the most important questions in understanding the prebiotic origin of life. Herein, we have demonstrated a spatiotemporal pH gradient formation pattern on a hydrogel surface by employing two different enzymatic reactions, namely, the reactions of glucose oxidase (pH decreasing) and urease (pH increasing). We found here a generic pattern of spatiotemporal change in pH and proton transfer catalytic activity that was completely altered in a cationic gold nanoparticle containing hydrogel. In the absence of nanoparticles, the gradually generated macroscopic pH gradient slowly diminished with time, whereas the presence of nanoparticles helped to perpetuate the generated gradient effect. This behavior is due to the differential responsiveness of the interface of the cationic nanoparticle in temporally changing surroundings with increasing or decreasing pH or ionic contents. Moreover, the catalytic proton transfer ability of the nanoparticle showed a concerted kinetic response following the spatiotemporal pH dynamics in the gel matrix. Notably, this nanoparticle-driven spatiotemporally resolved gel matrix will find applicability in the area of the membrane-free generation and control of spatially segregated chemistry at the macroscopic scale. This work reports perpetuating effect in enzymatically generated spatiotemporal pH gradient across a hydrogel in presence of cationic gold nanoparticle; showing a new route in spatially resolved chemistry in a membrane-free environment.![]()
Collapse
Affiliation(s)
- Rishi Ram Mahato
- Department of Chemical Sciences, Indian Institute of Science Education and Research (IISER) Mohali Knowledge City, Manauli 140306 India
| | - Ekta Shandilya
- Department of Chemical Sciences, Indian Institute of Science Education and Research (IISER) Mohali Knowledge City, Manauli 140306 India
| | - Subhabrata Maiti
- Department of Chemical Sciences, Indian Institute of Science Education and Research (IISER) Mohali Knowledge City, Manauli 140306 India
| |
Collapse
|
10
|
Mahato RR, Shandilya E, Dasgupta B, Maiti S. Dictating Catalytic Preference and Activity of a Nanoparticle by Modulating Its Multivalent Engagement. ACS Catal 2021. [DOI: 10.1021/acscatal.1c01991] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Affiliation(s)
- Rishi Ram Mahato
- Department of Chemical Sciences, Indian Institute of Science Education and Research (IISER) Mohali, Knowledge City, Manauli 140306, India
| | - Ekta Shandilya
- Department of Chemical Sciences, Indian Institute of Science Education and Research (IISER) Mohali, Knowledge City, Manauli 140306, India
| | - Basundhara Dasgupta
- Department of Chemical Sciences, Indian Institute of Science Education and Research (IISER) Mohali, Knowledge City, Manauli 140306, India
| | - Subhabrata Maiti
- Department of Chemical Sciences, Indian Institute of Science Education and Research (IISER) Mohali, Knowledge City, Manauli 140306, India
| |
Collapse
|
11
|
Deshwal A, Maiti S. Macromolecular Crowding Effect on the Activity of Liposome-Bound Alkaline Phosphatase: A Paradoxical Inhibitory Action. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2021; 37:7273-7284. [PMID: 34086469 DOI: 10.1021/acs.langmuir.1c01177] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
The cytoplasm of a cell is extremely crowded, with 20-30% being large biomolecules. This crowding enforces a significant amount of the physical and chemical barrier around biomolecules, so understanding any biomolecular event within the cellular system is challenging. Unsurprisingly, enzymes show a diverse kind of catalytic behavior inside a crowded environment and thus have remained an area of active interest in the last few decades. The situation can become even more complex and exciting in the case of understanding the behavior of a membrane-bound enzyme (almost 25-30% of enzymes are membrane-bound) in such a crowded environment that until now has remained unexplored. Herein, we have particularly investigated how a membrane-bound enzyme (using liposome-bound alkaline phosphatase) can behave in a crowded environment comprising polymer molecule-like poly(ethylene glycol) (PEG) of different weights (PEG400, PEG4000, and PEG9000) and Ficoll 400. We have compared the activity using a polymer microbead conjugated enzyme and have found that liposome-bound alkaline phosphatase had much higher activity in crowded environments, showing the importance and superiority of soft-deformable particles (i.e., vesicles) over hard spheres in macro-molecularly crowded media. Interstingly, we have found a paradoxical behavior of inhibitors in terms of both their extent and pathway of inhibitory action. For instance, phosphates, known as competitive inhibitors in buffer, behave as uncompetitive inhibitors in liposome-bound enzymes in crowded media with an ∼5-fold less inhibitory effect, whereas phenyl alanine (an uncompetitive inhibitor in buffer) did not show any inhibitory potential when the enzyme was membrane-bound and in crowded media containing PEG9000 (30 wt %). Overall, this demonstration elucidates aspects of membrane-bound enzymes in crowded media in terms of both catalytic behavior and inhibitory actions and can lead to further studies of the understanding of enzymatic behavior in such complex crowded environments having a dampening effect in regular diffusive transport.
Collapse
Affiliation(s)
- Akshi Deshwal
- Indian Institute of Science Education and Research (IISER) Mohali, Department of Chemical Sciences, Knowledge City, Manauli 140306, India
| | - Subhabrata Maiti
- Indian Institute of Science Education and Research (IISER) Mohali, Department of Chemical Sciences, Knowledge City, Manauli 140306, India
| |
Collapse
|
12
|
Shandilya E, Dasgupta B, Maiti S. Interconnectivity between Surface Reactivity and Self-Assembly of Kemp Elimination Catalyzing Nanorods. Chemistry 2021; 27:7831-7836. [PMID: 33769607 DOI: 10.1002/chem.202100450] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2021] [Indexed: 11/08/2022]
Abstract
Understanding the fundamental facts behind dynamicity of catalytic processes has been a longstanding quest across disciplines. Herein, we report self-assembly of catalytically active gold nanorods that can be regulated by tuning its reactivity towards a proton transfer reaction at different pH. Unlike substrate-induced templating and co-operativity, the enhanced aggregation rate is due to alteration of catalytic surface charge only during reactivity as negatively charged transition state of reactant (5-nitrobenzisoxazole) is formed on positively charged nanorod while undergoing a concerted E2-pathway. Herein, enhanced diffusivity during catalytic processes might also act as an additional contributing factor. Furthermore, we have also shown that nanosized hydrophobic cavities of clustered nanorods can also efficiently accelerate the rate of an aromatic nucleophilic substitution reaction, which also demonstrates a catalytic phenomenon that can lead to cascading of other reactions where substrates and products of the starting reactions are not directly involved.
Collapse
Affiliation(s)
- Ekta Shandilya
- Department of Chemical Sciences, Indian Institute of Science Education and Research (IISER) Mohali, Knowledge City, Manauli, 140306, India
| | - Basundhara Dasgupta
- Department of Chemical Sciences, Indian Institute of Science Education and Research (IISER) Mohali, Knowledge City, Manauli, 140306, India
| | - Subhabrata Maiti
- Department of Chemical Sciences, Indian Institute of Science Education and Research (IISER) Mohali, Knowledge City, Manauli, 140306, India
| |
Collapse
|