Department of Chemistry

Indian Institute of Technology Palakkad&nbsp;(IIT Palakkad or IIT PKD) is a public autonomous&nbsp;engineering&nbsp;and&nbsp;research&nbsp;institute located in&nbsp;Palakkad,&nbsp;Kerala. It was&nbsp;one of the five new&nbsp;IITs&nbsp;proposed in the&nbsp;2014 Union budget of India. The campus was inaugurated on 3 August 2015. The institute has 94 faculty, 978 students, and 63 non-teaching staffs.

IT Palakkad currently offers four-year Bachelor of Technology (B.Tech) and two years MS programmes in 8 different engineering disciplines including&nbsp;Computer Science, Electrical, Mechanical, Civil among others.

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IIT Palakkad

Herein, we report the first metal-free, redox-neutral strategy for radical cascade alkylative radical addition, cyclization of N-arylacrylamides with unactivated alkyl chlorides to give corresponding 3,3-disubstituted oxindoles in moderate to good yields. This transformation’s salient features are the utilization of an organo photocatalyst, mild reaction conditions and broad substrate scope. Moreover, this methodology is suitable for hetero cycle derived acrylamides and further allowed to utilize aryl chlorides for radical cyclization reaction. Finally, DFT studies allow us to shed light on the reaction mechanism. © 2023 American Chemical Society

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Journal of Organic Chemistry

Redox-Neutral Radical Cascade Cyclization of N-Arylacrylamides with Unactivated Alkyl and Aryl Chlorides

The architecture of molecules plays a significant role in their effective binding with another moiety. Direct comparison of a linear dithiocarbamate and its macrocyclic analogue was carried out, to explore the magnitude of these architectural effects for different biological and material science applications. Linear and macrocyclic compounds with the same functional groups, such as amide, dithiocarbamic ester, naphthyl, and propyl, were designed, synthesized, and compared through their spectral, physicochemical, and thermal properties. Utilizing dithiocarbamates, the compounds were used for the detoxification of water by removal of toxic heavy metals, including Hg2+, Cu2+, Cd2+, Pb2+, Zn2+, and Ni2+ by precipitation. In addition, comparable interactions with various important proteins, such as bovine serum albumin, human serum albumin, haemoglobin, lysozyme, proteinase, ribonuclease, and trypsin, were performed. The observation of better performance for the macrocycle towards protein interaction, and of the linear compound for removal of heavy metals is remarkable, and proves that the compound architecture is important. © 2023 The Royal Society of Chemistry.

New Journal of Chemistry

Dithiocarbamate-based linear versus macrocyclic architecture: comparative studies and applications in protein interaction and heavy metal removal

In this work, a library of functionally and structurally tuneable macromolecules were synthesised and their interaction with serum proteins were studied experimentally and theoretically, with an aim to identify the driving factors that influence protein-drug interaction. The parameters taken for assessment were (a) the number and type of functional groups (dithiocarbamate, ester and amide) present in the backbone and sidechain, (b) different architectures including linear and branched, and (c) hydrophobic/hydrophilic character. Dansyl moiety was attached to make these macromolecules a suitable acceptor for FRET with serum proteins. The binding constant values calculated from the fluorescence titrations indicated that an optimum hydrophobic character, chain length and architecture are essential for a favourable interaction with BSA/HSA. By changing the above mentioned three factors, we were able to achieve a wide range of binding constant values in the range of (2.99–7.91) × 104 M−1 for BSA and (1.64–11.7) × 104 M−1 for HSA. The number of binding sites varied from 1.13 to 1.69 for BSA and 0.89 to 1.35 for HSA. Also, the energy transfer efficiency was calculated and it falls in the range of 63.9–88.7% and 52.0–84.2% respectively for BSA and HSA. The quenching mechanism for serum protein-drug complex was found to involve both static and dynamic quenching. Moreover, this structure–activity relationship was also backed by molecular docking studies. © 2023 Elsevier B.V.

Journal of Photochemistry and Photobiology A: Chemistry

Probing the interactions of dansyl appended sequence-defined oligomers with serum albumins: Effect of functionality, hydrophobicity, and architecture

In this work, two water soluble fluorescent non-conjugated polymers have been designed and synthesized. To confer water solubility, a synthetic strategy was made to incorporate secondary amine moieties and ester linkages in the backbone, and to make it fluorescent we have attached dansyl and naphthyl moieties. The polymers exhibited solid-state fluorescence which was confirmed by solid-state fluorescence spectroscopy and microscopy. They also exhibited aggregation induced emission (AIE) behaviour in a water-DMSO mixture which was confirmed by fluorescence, quantum yield, DLS, and lifetime analysis. Furthermore, the interaction of the polymers with different metal ions was studied with the aim of using it as a sensor. Among the 15 metal ions tested, it was found that the dansyl appended polymer gave distinct signals in the absorption and emission spectra for the addition of Cu2+, Co2+, Ag+, K+, Fe2+ and Fe3+ ions. These metals also showed discrete signals in the absorption spectra along with distinguishable colour changes such as Cu2+ - blue, Co2+ - pink, Ag+ - purple, Fe2+ - dark yellow and Fe3+ - light yellow on their addition. Further linear discriminant analysis (LDA) was performed to see the sensor array applications of the polymer and showed a discrete sensor array output and clear separation of clusters, validating the application of the polymer as a multi-analyte sensor. The separation and identification of the metals via LDA was also possible in nanomolar concentrations. Moreover, our strategy for developing a fluorescent polymer is also versatile for synthesising polymers with tuneable properties for diverse applications. © 2023 The Royal Society of Chemistry.

Polymer Chemistry

Water soluble non-conjugated fluorescent polymers: aggregation induced emission, solid-state fluorescence, and sensor array applications

Pathologies related to cardiovascular diseases mostly emerge as a result of oxidative stress buildup in cardiomyocytes. The heavy load of mitochondrial oxidative phosphorylation in cardiac tissues corresponds to a surge in oxidative stress leading to mitochondrial dysfunction and cellular apoptosis. Thus, scavenging the reactive oxygen species (ROS) linked to mitochondria can significantly improve cardio-protection. Epigallocatechin-3-gallate (EGCG), the major polyphenol found in green tea has been extensively studied for its profound health-beneficial activities. Herein, we designed and synthesized a series of mitochondrial-targeting EGCG derivatives, namely MitoEGCGn (n = 4, 6, 8) by incorporating triphenylphosphonium ion onto it using different linkers. MitoEGCGn were found to be non-toxic to H9c2 rat cardiomyocyte cells even at higher doses in comparison to its parent molecule EGCG. Interestingly, MitoEGCG4 and MitoEGCG6 protected the H9c2 cardiomyocyte cells from the oxidative damage induced by H2O2 whereas EGCG was found to be toxic and ineffective in protecting the cells from H2O2 damage. MitoEGCG4 and MitoEGCG6 also protected the cells from the H2O2-induced disruption of mitochondrial membrane potential as well as activation of apoptosis as revealed by pro-caspase 3 expression profile, DNA fragmentation assay and AO/EtBr staining. Taken together, our study shows that the mitochondria targeting EGCG derivatives were able to effectively combat the H2O2-induced oxidative stress in H9c2 cardiomyocytes. They eventually augmented the mitochondrial health of cardiomyocytes by maintaining the mitochondrial function and attenuating apoptosis. Overall, MitoEGCG4 and MitoEGCG6 could provision a cardioprotective role to H9c2 cardiomyocytes at the time of oxidative insults related to mitochondrial dysfunction-associated injuries. © 2023 The Royal Society of Chemistry.

RSC Advances

Mitochondria-targeting EGCG derivatives protect H9c2 cardiomyocytes from H2O2-induced apoptosis: design, synthesis and biological evaluation

In the last two decades, an incredible amount of effort has been put forth to gain a molecular level understanding of human pathophysiology through genome sequencing projects and human proteome projects. Despite that, there is a lot more to discover with respect to complex molecular and biochemical networks in cellular and tissue-specific functions which are largely mediated by proteins and their modifications. With the advent of the post-genomic era, scientists have developed an inherent interest in interdisciplinary approaches and accredited proteomics studies with powerful chemical probe molecules as a result of carefully designed synthetic chemistry. Chemoproteomics is one such tool that provides an opportunity to screen interactions between small molecule drugs and proteins in their native cellular environments and simultaneously understand the preceding mechanism of action. This chapter discusses how chemoproteomics has helped us evolve from phenotype-based drug discovery to target-based drug discovery by shedding light on the different methods for the identification and validation of protein targets interacting with the small molecule drugs. Given its contribution to the field of drug discovery and biomarker identification, it is apt to discuss the importance of chemoproteomics in the field of biotechnology and the advancements it has brought to the pharmaceutical sciences © 2023 Munishwar Nath Gupta.

Some Key Topics in Chemistry and Biochemistry for Biotechnologists

Chemoproteomics: An Extremely Powerful Kit in Drug Discovery Toolbox

Fluorescence chemosensors for selective sensing and quantification of biologically important metal ions have attracted substantial research interest in recent years. Cu(ii) is the third most abundant transition metal ion and an essential heavy metal ion present in the human body. Cu(ii) plays many essential functions in living systems as a catalytic co-factor in various enzyme functions and electron transport. The alteration in the essential concentration of Cu(ii) causes several deadly diseases like Menke's syndrome, Wilson's disease and Alzheimer's disease. Given this, in the past decades, many small-molecule fluorescence sensors have been developed and employed for trace detection and monitoring the concentration of Cu(ii) ions in biological systems. In particular, amino-1,8-naphthalimide fluorescence sensors have gained special research interest for Cu(ii) sensing because of their facile synthesis, easy functional, structure tunability and strong fluorescence emission in the visible region. In this article, we have discussed the applications of various amino-1,8-naphthalimide-based small-molecule fluorescence chemosensors for selective sensing and bioimaging of Cu(ii) ions. In each section, we provide a detailed report on the synthesis, photophysics and fluorescence sensing properties including bioimaging of amino-1,8-naphthalimide-small-molecule fluorescence chemosensors for Cu(ii) ions. © 2023 RSC.

Sensors and Diagnostics

Fluorescence sensing and bioimaging of Cu(ii) ions using amino-1,8-naphthalimide-based small-molecule chemosensors

Organoarsenics are low-toxicity compounds that are used widely as feed additives to promote livestock growth, enhance meat pigmentation, and fight against intestinal parasites. The organoarsenic compounds are commonly found in poultry waste and the degradation of organoarsenic produces the toxic carcinogen inorganic arsenic such as As(v) and As(iii), which results in severe arsenic pollution of soil and groundwater. As a consequence, there exists a high necessity to develop suitable sensing methods for the trace detection and quantification of organoarsenic feed additives in wastewater. Among various detection methods, in particular, fluorescence-based sensing has become a popular and efficient method used extensively for sensing water contaminants and environmental contaminants. In the recent past, a wide variety of fluorescence chemosensors have been designed and employed for the efficient sensing and quantification of the concentration of organoarsenic feed additives in different environmental samples. This review article systematically highlights various fluorescence chemosensors reported to date for fluorescence-based sensing of organoarsenic feed additives. The fluorescence sensors discussed in this review are classified and grouped according to their structures and functions, and in each section, we provide a detailed report on the structure, photophysics, and fluorescence sensing properties of different chemosensors. Lastly, the future perspectives on the design and development of practically useful sensor systems for selective and discriminative sensing of organoarsenic compounds have been stated. © 2023 The Royal Society of Chemistry.

Chemical Communications

Recent advances in fluorescence-based chemosensing of organoarsenic feed additives using luminescence MOFs, COFs, HOFs, and QDs

A straightforward and disposable electrochemical sensor was developed by the direct electrodeposition of silver nanoparticles (AgNPs) on a conducting polymer and an acid-functionalized carbon nanotube-modified screen-printed carbon electrode (f-CNT/SPCE) for the detection of the antiviral drug valganciclovir (VGC). A scaffold layer of the conducting polymer 2,6-diaminopyridine (p-DAP) was electrodeposited on an f-CNT/SPCE surface via a potentiodynamic polarization method. Later, homogeneous deposition of AgNPs was carried out on the polymer-modified scaffold layers. The electrode activities related to the concentration of the polymer substrate and the AgNP precursor were systematically optimized. The electrochemical oxidation of VGC by SPCE/f-CNT/p-DAP-AgNPs was investigated by square-wave voltammetry. The modified sensor exhibited an attractive electroanalytical performance toward VGC with high sensitivity (nanomolar range), selectivity (in the presence of uric acid and dopamine), reproducibility, and long-term storage stability. Potential real-world applications of the modified screen-printed sensor were demonstrated using artificial urine/serum and industrial water samples. The straightforward design and attractive analytical performance of the conductive polymer-embedded AgNP -modified screen-printed sensor suggest considerable promise for use of this sensor in the point-of-care screening of antiviral drugs. The sensor strip would also be useful in the screening of antiviral drugs in industrial (quality control) and environmental (industry effluents) applications. © 2023 American Chemical Society.

ACS Applied Nano Materials

Electrochemical Strip Sensor Based on a Silver Nanoparticle-Embedded Conducting Polymer for Sensitive In Vitro Detection of an Antiviral Drug

Serotonin (5-hydroxytryptamine (5-HT)) is one of the important neurotransmitters which is released from the endocrine system. An abnormal level of this biomarker leads to several neurological diseases. The accurate assessment of serotonin is the utmost option to start treatment in the early stages of the disease. The current work is focused on the development of a disposable, screen-printed electrochemical sensor for the depression biomarker, serotonin in the physiological pH medium (pH 7.4) with the aid of a hexagonal, Ni(OH)2-nanoplate (NH-HNP)-embedded chitosan (Chit) and modified, screen-printed carbon electrode (SPCE). Initially, hexagonal nanoplates of Ni(OH)2 were synthesized by an eco-friendly and simple hydrothermal method. The prepared materials were well characterized by advanced analytical techniques to examine the physicochemical properties of the synthesized Ni(OH)2 hexagonal nanoplates. From the cyclic voltametric (CV) analysis, it was found that the oxidative current response of 5-HT at a NH-HNP-modified SPCE has about fivefold higher current values than over bare SPCE. The scan rate studies of NH-HNP-Chit/SPCE electrodes revealed that the oxidation mechanism of 5-HT is controlled by the diffusion behavior of the analyte. Differential pulse voltammetric tests of the NH-HNP-Chit/SPCE electrode exhibited a linear response in the dynamic concentration range of 0.1 to 30 µM, with a detection limit of about 60 nM. The sensor response is very reproducible from electrode to electrode, and the deactivation or surface-fouling of the sensor was not observed within the several experimental measurements. The sensor exhibited excellent storage stability over a period of twenty days. Finally, the fabricated, disposable SPCE sensor has shown respectable activity for the detection of depression biomarker 5-HT from synthetic urine and saliva samples. © 2023 by the authors.