Subhabrata Maiti - Academia.edu (original) (raw)

Papers by Subhabrata Maiti

Nature communications, Apr 29, 2024

Chemical Communications, 2022

The modulatory behavior of adenine-based nucleotides on the catalytic and micropumping ability of... more The modulatory behavior of adenine-based nucleotides on the catalytic and micropumping ability of acetylcholine esterase in blood plasma has been demonstrated.

ChemNanoMat, 2022

Rationalizing changes in functional properties by an exogenous module in a synthetic nanoscale se... more Rationalizing changes in functional properties by an exogenous module in a synthetic nanoscale self‐organized system has broader significance in designing responsive biomimic materials having application in catalysis to therapeutics. Herein, we have developed a substrate‐driven nanoscale vesicular assembly of a metallosurfactant (with dipicolylamine co‐ordinated with zinc ion as headgroup) which simultaneously acts as a cooperative catalyst for the hydrolysis of the RNA‐model substrate, 2‐hydroxypropyl‐4‐nitrophenylphosphate (HPNPP). We have found out that both purine and pyrimidine‐based nucleoside monophosphates interact differently with the assembly, modulating the rate of catalytic cleavage. The different means of recognition of the nucleobases leads to alteration in membrane fluidity as well as surface charge of the vesicular aggregates whether the assembly is in catalytically active or inactive state. Then a systematic pattern for different nucleotides mediated vesicular nanos...

Langmuir, 2021

The cytoplasm of a cell is extremely crowded, with 20-30% being large biomolecules. This crowding... more 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.

Langmuir, 2019

The nascent field of microscale flow chemistry focuses on harnessing flowing fluids to optimize c... more The nascent field of microscale flow chemistry focuses on harnessing flowing fluids to optimize chemical reactions in microchambers and establish new routes for chemical synthesis. With enzymes and other catalysts anchored to the surface of microchambers, the catalytic reactions can act as pumps and propel the fluids through the containers. Hence, the flows not only affect the catalytic reactions, but these reactions also affect the flows. Understanding this dynamic interplay is vital to enhancing the accuracy and utility of flow technology. Through experiments and simulation, we design a system of three different enzymes, immobilized in separate gels, on the surface of a microchamber; with the appropriate reactants in the solution each enzymefilled gel acts as a pump. The system also exploits a reaction cascade that controls the temporal interactions between two pumps. With three pumps in a triangular arrangement, the spatiotemporal interactions among the chemical reactions become highly coordinated and produce well-defined fluid streams, which transport chemicals and form a fluidic "circuit". The circuit layout and flow direction of each constituent stream can be controlled through the number and placement of the gels, and the types of catalysts localized in the gels. These studies provide a new route for forming self-organizing and bifurcating fluids that can yield fundamental insight into non-equilibrium, dynamical systems. Because the flows and fluidic circuits are generated by internal chemical reactions, the fluids can autonomously transport cargo to specific locations in the device. Hence, the findings also provide guidelines to facilitate further automation of microfluidic devices.

Physical Chemistry Chemical Physics, 2021

Alkaline phosphatase, hexokinase, and glucose oxidase either aggregate or fragment after addition... more Alkaline phosphatase, hexokinase, and glucose oxidase either aggregate or fragment after addition of species directly related to their catalysis. This shows that specific multimeric structures of native enzymes may not be retained during catalysis.

The theory behind origin of life to Darwinian evolution considers emergence of dissipative struct... more The theory behind origin of life to Darwinian evolution considers emergence of dissipative structures driven by the flow of energy across all length scales. To this end, developing and deeper understanding of non-equilibrium self-assembly processes under continuous supply of energy is a demanding matter, both in fundamental and application (for e.g. developing dynamic materials) viewpoint. Herein, we demonstrate transient self-assembly of a DNA-histone condensate where trypsin (already present in the system) hydrolyse histone resulting disassembly. As the process is short-lived, the information of intermediate states between complete assembly and disassembly remains uncaptured in absence of any external energy. We show that performing the process under electric field of varying strength results fractionation of myriad of short-lived states which appears as band in different zone. Deconvolution and capturing of many hidden self-assembling species of similar components but of differen...

Directional interactions and assembly of nanobioconjugate in clusters at specific location are im... more Directional interactions and assembly of nanobioconjugate in clusters at specific location are important for patterning, microarrays to biomedical research. Herein, we report self-assembly and spatial control in surface patterning of the surfactant-functionalized nanoparticles can be governed in macroscale environment by two factors – synergistic enzyme-substrate-nanoparticle affinity and phoretic effect. Firstly, we showed aggregation of cationic gold nanoparticle (GNP) can be modulated by multivalent anionic nanoparticle binding adenosine-based nucleotide and enzyme, alkaline phosphatase. We further demonstrated two different types of their autonomous aggregation pattern – (i) by introducing enzyme gradient which modulates the synergistic non-equilibrium interactivity of the nanoparticle, nucleotide and enzyme in macroscale and (ii) surface deposition pattern from evaporating droplet via coffee ring effect. Finally, we showed change in capillary phoresis parameters responsible for...

Chemical Science, 2022

We have shown ATP-driven spatiotemporally distinct self-organization pattern of a surfactant in a... more We have shown ATP-driven spatiotemporally distinct self-organization pattern of a surfactant in a two-dimensional space using enzymes, demonstrating a new route for obtaining ‘spatial’ organizational adaptability among interacting components.

Angewandte Chemie International Edition, 2020

Nature adopts complex chemical networks to finely tune biochemical processes. Indeed, small biomo... more Nature adopts complex chemical networks to finely tune biochemical processes. Indeed, small biomolecules play a key role in regulating the flux of metabolic pathways. Chemistry, which was traditionally focused on reactions in simple mixtures, is dedicating increasing attention to the network reactivity of highly complex synthetic systems, able to display new kinetic phenomena. Herein, we show that the addition of monophosphate nucleosides to a mixture of amphiphiles and reagents leads to the selective templated formation of self‐assembled structures, which can accelerate a reaction between two hydrophobic reactants. The correct matching between nucleotide and the amphiphile head group is fundamental for the selective formation of the assemblies and for the consequent up‐regulation of the chemical reaction. Transient stability of the nanoreactors is obtained under dissipative conditions, driven by enzymatic dephosphorylation of the templating nucleotides. These results show that smal...

Chemical Communications, 2020

A lag time between addition of a trigger and the emergence of a fluorescence signal is observed i... more A lag time between addition of a trigger and the emergence of a fluorescence signal is observed in an ATP-fueled self-assembly process under dissipative conditions.

ChemSystemsChem, 2019

Multivalent chemical fuel driven transient assembly plays a critical role in biological processes... more Multivalent chemical fuel driven transient assembly plays a critical role in biological processes. This inspires chemists to design synthetic systems having transient and dynamic functionalities. However, a detailed understanding about the temporal evolution of each of the intermediate species in a multi‐step assembly under dissipative conditions has not yet been explored. Herein, we have shown under dissipative conditions, how the strength of dissipation can modulate the compositional behavior of each of the intermediate species during their survival period by using kinetic modeling (with Python). We have observed that the appearance and disappearance of intermediates (formed either at the first or penultimate assembly step) are highly non‐linear in nature, and it is possible to trap any of the desired intermediates or a mixture of them of certain compositions at a definite time interval simply by tuning the strength of dissipation.

Chemical Communications, 2018

A two-step hierarchical self-assembly process is presented relying on the GMP-induced formation o... more A two-step hierarchical self-assembly process is presented relying on the GMP-induced formation of vesicles, which then cluster into large aggregates upon the addition of Ag+-ions.

Angewandte Chemie International Edition, 2018

The transient activation of function using chemical fuels is common in nature, but much less in s... more The transient activation of function using chemical fuels is common in nature, but much less in synthetic systems. Progress towards the development of systems with a complexity similar to that of natural ones requires chemical fuel selectivity. Here, we show that a self‐assembled nanosystem, composed of monolayer‐protected gold nanoparticles and a fluorogenic peptide, is activated for transient signal generation only in case the chemical fuel matches the recognition site present at the nanoparticle surface. A modification of the recognition site in the nanosystem completely changes the chemical fuel selectivity. When two nanosystems are simultaneously present, the selectivity expressed by the system depends on the concentration of nucleotide added.

Tetrahedron, 2017

Here we describe a self-assembled sensing system composed of three separate modules: gold nanopar... more Here we describe a self-assembled sensing system composed of three separate modules: gold nanoparticles, a reporter element, and a recognition element. The gold nanoparticles serve as a multivalent platform for the interaction with both the reporter and recognition element and the gold nucleus serves to affect the fluorescent properties of the reporter. The reporter element serves for generation of the output signal. The recognition element serves to make the assay selective. The working principle is that the interaction of the analyte with the recognition element leads to an increased affinity for the gold nanoparticle, which causes a displacement of the reporter and a turn-ON of fluorescence. It is shown that the modular nature of the system permits straightforward tuning of the dynamic detection range, the sensitivity, and the selectivity, simply by changing the recognition module. The system can detect Hg 2+ and Ag + metal ions at nanomolar concentrations in aqueous buffer.

Current opinion in biotechnology, 2017

Over the past decades, chemists have mastered the art of assembling small molecules into complex ... more Over the past decades, chemists have mastered the art of assembling small molecules into complex nanostructures using non-covalent interactions. The driving force for self-assembly is thermodynamics: the self-assembled structure is more stable than the separate components. However, biological self-assembly processes are often energetically uphill and require the consumption of chemical energy. This allows nature to control the activation and duration of chemical functions associated with the assembled state. Synthetic chemical systems that operate in the same way are essential for creating the next generation of intelligent, adaptive materials, nanomachines and delivery systems. This review focuses on synthetic molecular nanostructures which self-assemble under dissipative conditions. The chemical function associated with the transient assemblies is operational as long as chemical fuel is present.

Chemistry (Weinheim an der Bergstrasse, Germany), Jan 23, 2017

The next generation of adaptive, intelligent chemical systems will rely on a continuous supply of... more The next generation of adaptive, intelligent chemical systems will rely on a continuous supply of energy to maintain the functional state. Such systems will require chemical methodology that provides precise control over the energy dissipation process, and thus, the lifetime of the transiently activated function. This manuscript reports on the use of structurally diverse chemical fuels to control the lifetime of two different systems under dissipative conditions: transient signal generation and the transient formation of self-assembled aggregates. The energy stored in the fuels is dissipated at different rates by an enzyme, which installs a dependence of the lifetime of the active system on the chemical structure of the fuel. In the case of transient signal generation, it is shown that different chemical fuels can be used to generate a vast range of signal profiles, allowing temporal control over two orders of magnitude. Regarding self-assembly under dissipative conditions, the abil...

Chemical Science

This work reports perpetuating effect in enzymatically generated spatiotemporal pH gradient acros... more 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.

Nature Chemistry, 2016

Dissipative self-assembly is exploited by nature to control important biological functions, such ... more Dissipative self-assembly is exploited by nature to control important biological functions, such as cell division, motility and signal transduction. The ability to construct synthetic supramolecular assemblies that require the continuous consumption of energy to remain in the functional state is an essential premise for the design of synthetic systems with lifelike properties. Here, we show a new strategy for the dissipative self-assembly of functional supramolecular structures with high structural complexity. It relies on the transient stabilization of vesicles through noncovalent interactions between the surfactants and adenosine triphosphate (ATP), which acts as the chemical fuel. It is shown that the lifetime of the vesicles can be regulated by controlling the hydrolysis rate of ATP. The vesicles sustain a chemical reaction but only as long as chemical fuel is present to keep the system in the out-of-equilibrium state. The lifetime of the vesicles determines the amount of reaction product produced by the system.