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1.
Nanoscale Adv ; 6(9): 2390-2406, 2024 Apr 30.
Article in English | MEDLINE | ID: mdl-38694474

ABSTRACT

The delicate synthesis of one-dimensional (1D) carbon nanostructures from two-dimensional (2D) graphene moiré layers holds tremendous interest in materials science owing to its unique physiochemical properties exhibited during the formation of hybrid configurations with sp-sp2 hybridization. However, the controlled synthesis of such hybrid sp-sp2 configurations remains highly challenging. Therefore, we employed a simple hydrothermal technique using agro-industrial waste as the carbon source to synthesize 1D carbyne nanocrystals from the nanoconstricted zones of 2D graphene moiré layers. By employing suite of characterization techniques, we delineated the mechanism of carbyne nanocrystal formation, wherein the origin of carbyne nanochains was deciphered from graphene intermediates due to the presence of a hydrothermally cut nanoconstriction regime engendered over well-oriented graphene moiré patterns. The autogenous hydrothermal pressurization of agro-industrial waste under controlled conditions led to the generation of epoxy-rich graphene intermediates, which concomitantly gave rise to carbyne nanocrystal formation in oriented moiré layers with nanogaps. The unique growth of carbyne nanocrystals over a few layers of holey graphene exhibits excellent paramagnetic properties, the predominant localization of electrons and interfacial polarization effects. Further, we extended the application of the as-synthesized carbyne product (Cp) for real-time electrochemical-based toxic metal (As3+) sensing in groundwater samples (from riverbanks), which depicted superior sensitivity (0.22 mA µM-1) even at extremely lower concentrations (0.0001 µM), corroborating the impedance spectroscopy analysis.

2.
ACS Chem Neurosci ; 15(2): 222-229, 2024 01 17.
Article in English | MEDLINE | ID: mdl-38164894

ABSTRACT

Development of multifunctional theranostics is challenging and crucial for deciphering complex biological phenomena and subsequently treating critical disease. In particular, development of theranostics for traumatic brain injury (TBI) and understanding its repair mechanism are challenging and highly complex areas of research. Recently, there have been interesting pieces of research work demonstrated that a small molecule-based neuroregenerative approach using stem cells has potential for future therapeutic lead development for TBI. However, these works demonstrated the application of a mixture of multiple molecules as a "chemical cocktail", which may have serious toxic effects in the differentiated cells. Therefore, development of a single-molecule-based potential differentiating agent for human mesenchymal stem cells (hMSCs) into functional neurons is vital for the upcoming neuro-regenerative therapeutics. This lead could be further extraploted for the design of theranostics for TBI. In this study, we have developed a multifunctional single-molecule-based fluorescent probe, which can image the transdifferentiated neurons as well as promote the differentiation process. We demonstrated a promising class of fluorescent probes (CP-4) that can be employed to convert hMSCs into neurons in the presence of fibroblast growth factor (FGF). This fluorescent probe was used in cellular imaging as its fluorescence intensity remained unaltered for up to 7 days of trans-differentiation. We envision that this imaging probe can have an important application in the study of neuropathological and neurodegenerative studies.


Subject(s)
Brain Injuries, Traumatic , Mesenchymal Stem Cells , Humans , Fluorescent Dyes/metabolism , Neurons/metabolism , Cell Differentiation , Brain Injuries, Traumatic/therapy , Brain Injuries, Traumatic/metabolism , Cell Transdifferentiation
3.
Nano Today ; 35: 101001, 2020 Dec.
Article in English | MEDLINE | ID: mdl-33052202

ABSTRACT

Preventing the trajectory of human coronaviruses including the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic could rely on the sprint to design a rational roadmap using breakneck strategies to counter its prime challenges. Recently, carbon quantum dots (CQDs), zero-dimensional (0D) carbon-based nanomaterials, have emerged as a fresh antiviral agent owing to their unique physicochemical properties. Additionally, doping instils beneficial properties in CQDs, augmenting their antiviral potential. The antiviral properties of CQDs can be reinforced by heteroatom doping. Bestowed with multifaceted features, functionalized CQDs can interact with the spike protein of the human coronaviruses and perturb the virus-host cell recognition. Recently, triazole derivatives have been explored as potent inhibitors of human coronaviruses by blocking the viral enzymes such as 3-chymotrypsin-like protease (3CLpro) and helicase, important for viral replication. Moreover, they offer a better aromatic heterocyclic core for therapeutics owing to their higher thermodynamic stability. To curb the current outbreak, triazole functionalized heteroatom co-doped carbon quantum dots (TFH-CQDs) interacting with viral cells spanning the gamut of complexity can be utilized for deciphering the mystery of its inhibitory mechanism against human coronaviruses. In this quest to unlock the potential of antiviral carbon-based nanomaterials, CQDs and triazole conjugated CQDs template comprising a series of bioisosteres, CQDs-1 to CQDs-9, can extend the arsenal of functional antiviral materials at the forefront of the war against human coronaviruses.

4.
ACS Omega ; 5(30): 18958-18967, 2020 Aug 04.
Article in English | MEDLINE | ID: mdl-32775897

ABSTRACT

Alzheimer's disease (AD) exhibits a multitude of syndromes which add up to its complex nature. In AD, amyloid plaques are deposited along with abnormal accumulation of transition-metal ions. These transition-metal ions are redox-active and help to induce the formation of various polymorphic forms of amyloid-ß. Amyloid oligomeric and fibrillar aggregates are the main cause for neuronal toxicity. Another reason for neuronal toxicity arises from generation of reactive oxygen species (ROS) catalyzed by redox-active metal ions through Fenton's reaction. In this direction, an Aß inhibitor possessing the metal chelation property will be the most promising approach against multifaceted AD. Herein, a rhodamine-B-based compound (Rh-BT) has been designed and synthesized. Rhodamine was attached with benzothiazole as a recognition unit for amyloid-ß aggregates. The molecule can effectively capture redox metal ions from the Aß-Cu2+ complex as well as inhibit Aß self-assembly such as toxic oligomeric and fibrillar aggregates. Various biophysical assays show that Rh-BT interacts with the Aß peptide, is capable of decreasing metal-induced ROS generation, and inhibits Aß-Cu2+-induced cytotoxicity. All these results support the multifunctional nature of Rh-BT, which has an Aß-specific recognition unit. In addition to the above properties, Rh-BT also exhibits good serum stability in vivo and blood-brain barrier permeability. Therefore, Rh-BT can be considered as a potent multifunctional therapeutic for the treatment of AD.

5.
ACS Omega ; 4(5): 9361-9366, 2019 May 31.
Article in English | MEDLINE | ID: mdl-31460025

ABSTRACT

Discovery of a nontoxic fluorescent molecular probe to "light up" specific cellular organelles is extremely essential to understand dynamics of intracellular components. Here, we report a new nontoxic mitochondria-targeted linear bithiazole compound, containing trifluoroacetyl terminal groups, which emits intense blue fluorescence and stained mitochondria of various cells. Interestingly, the power of fluorescence is completely off when the bithiazole unit is stapled by a carbonyl bridge.

6.
Chem Commun (Camb) ; 55(16): 2356-2359, 2019 Feb 19.
Article in English | MEDLINE | ID: mdl-30724319

ABSTRACT

An indole-rich tripodal microtubule inhibitor is designed, which binds at the DCVJ site of tubulin and inhibits its polymerization. It causes apoptotic death of cancer cells without affecting normal cells and inhibits the growth of tumors. Finally, STD-NMR and TR-NOESY experiments reveal that the indole appendages play a crucial role in interacting with tubulin.

7.
ACS Chem Neurosci ; 10(3): 1506-1516, 2019 03 20.
Article in English | MEDLINE | ID: mdl-30565916

ABSTRACT

Microtubules play a crucial role in maintenance of structure, function, axonal extensions, cargo transport, and polarity of neurons. During neurodegenerative diseases, microtubule structure and function get severely damaged due to destabilization of its major structural proteins. Therefore, design and development of molecules that stabilize these microtubule networks have always been an important strategy for development of potential neurotherapeutic candidates. Toward this venture, we designed and developed a tyrosine rich trisubstituted triazine molecule (TY3) that stabilizes microtubules through close interaction with the taxol binding site. Detailed structural investigations revealed that the phenolic protons are the key interacting partners of tubulin. Interestingly, we found that this molecule is noncytotoxic in PC12 derived neurons, stabilizes microtubules against nocodazole induced depolymerization, and increases expression of acetylated tubulin (Ac-K40), an important marker of tubulin stability. Further, results show that TY3 significantly induces neurite sprouting as compared to the untreated control as well as the two other analogues (TS3 and TF3). It also possesses anti-Aß fibrillation properties as confirmed by ThT assay, which leads to its neuroprotective effect against amyloidogenic induced toxicity caused through nerve growth factor (NGF) deprivation in PC12 derived neurons. Remarkably, our results reveal that it reduces the expression of TrkA (pY490) associated with NGF deprived amyloidogenesis, which further proves that it is a potent amyloid ß inhibitor. Moreover, it promoted the health of the rat primary cortical neurons through higher expression of key neuronal markers such as MAP2 and Tuj1. Finally, we observed that it has good serum stability and has the ability to cross the blood-brain barrier (BBB). Overall, our work indicates the importance of phenolic -OH in promoting neuroprotection and its importance could be implemented in the development of future neurotherapeutics.


Subject(s)
Microtubules/metabolism , Neuroprotective Agents/metabolism , Neuroprotective Agents/pharmacology , Phenol/pharmacology , Tyrosine/metabolism , Tyrosine/pharmacology , Animals , Blood-Brain Barrier/cytology , Blood-Brain Barrier/drug effects , Blood-Brain Barrier/metabolism , Cells, Cultured , Cerebral Cortex/cytology , Cerebral Cortex/drug effects , Cerebral Cortex/metabolism , Female , Microtubules/drug effects , PC12 Cells , Pregnancy , Protein Stability/drug effects , Rats , Rats, Sprague-Dawley
8.
Anal Chem ; 87(17): 9002-8, 2015 Sep 01.
Article in English | MEDLINE | ID: mdl-26246182

ABSTRACT

Heterobis imine Schiff base probe L is able to discriminate geometrical isomers (maleic acid vs fumaric acid) through sharp colorimetric as well as fluorogenic responses even conspicuous with the naked eye. Colorimetric as well as fluorogenic sensing of maleic acid among various carboxylic acids was also demonstrated in ethanol-buffer medium. Sensing behavior of L was corroborated by (1)H NMR spectra, mass spectrometry, and theoretical calculations. Subsequently sensing behavior of L was used to probe maleic acid in starch rich food samples.


Subject(s)
Fluorometry , Food Additives/chemistry , Fumarates/analysis , Fumarates/chemistry , Maleates/analysis , Maleates/chemistry , Colorimetry , Fluorescent Dyes/chemistry , Imines/chemistry , Isomerism , Molecular Structure , Schiff Bases/chemistry , Solutions , Time Factors
9.
Anal Chim Acta ; 882: 76-82, 2015 Jul 02.
Article in English | MEDLINE | ID: mdl-26043094

ABSTRACT

A new tricarbocyanine-based chemosensor exhibited a dramatic Al(3+)-specific fluorescence turn-on response in the near-infrared (NIR) region. The receptor was found to be highly selective towards Al(3+) over other metal ions in physiological condition. The sensor was non-toxic and could thus be employed as an imaging probe for detecting intracellular Al(3+) in live cells. Interestingly, upon interaction with DNA in solution, the L-Al(3+) ensemble rendered tracking of DNase activity in solution through a systematic reduction in the fluorescence emission intensity.


Subject(s)
Aluminum/analysis , Deoxyribonucleases/metabolism , Animals , Cattle , HeLa Cells , Humans , Limit of Detection , Solutions , Spectrometry, Fluorescence , Spectrophotometry, Ultraviolet
10.
Dalton Trans ; 44(9): 4123-32, 2015 Mar 07.
Article in English | MEDLINE | ID: mdl-25622931

ABSTRACT

A pyridine-2-carbohydrazide functionalized conjugated fluorophoric Schiff base ligand (L1) specifically senses Al(3+) and Cd(2+) ions through significant changes in its absorption and emission spectral behavior, respectively, in physiological conditions. The spectral changes are in the visible region of the spectrum and thus facilitate naked eye detection. Apart from the visible changes, an in-field device application was demonstrated by sensing these ions in paper strips coated with L1. The crystal structure of the L1-Cd complex provided additional insight of the metal coordination attributes of L1. Interestingly, fluorescence microscopic studies demonstrated that the ligand L1 could also be used as an effective probe in imaging experiments for the detection of intracellular Cd(2+) ions in HeLa cells, without any toxicity to these model human cells.


Subject(s)
Aluminum/analysis , Cadmium/analysis , Coordination Complexes/chemistry , Hydrazines/chemistry , Pyridines/chemistry , Aluminum/chemistry , Aluminum/pharmacology , Cadmium/chemistry , Cadmium/pharmacology , Cell Survival/drug effects , Coordination Complexes/pharmacology , Crystallography, X-Ray , HeLa Cells , Humans , Ligands , Microscopy, Fluorescence , Schiff Bases/chemistry
12.
Anal Chem ; 85(17): 8369-75, 2013 Sep 03.
Article in English | MEDLINE | ID: mdl-23905654

ABSTRACT

A diformyl-quinoline based receptor (L1) exhibits selective colorimetric and fluorometric sensing of Zn(2+) in aqueous medium at pH 7.4 based on the intraligand charge transfer (ICT) process. The in situ formed phenoxo-bridged complex, L1·2Zn can selectively and specifically sense PPi among all the other biologically important anions including ATP through reversible binding. The detection limit for Zn(2+) and PPi were found to be approximately 56 and 2 ppb, respectively. The unique selectivity of the PPi by the L1-Zn ensemble could be used as an analytical tool to probe PPi generation in a prototype polymerase chain reaction (PCR) setup and track DNA amplification with higher sensitivity as compared to conventional agarose gel electrophoresis. Interestingly, the principle of PPi estimation in PCR rendered rapid estimation of bacterial cell numbers with a limit of detection of 10 CFU of Escherichia coli MTCC 433 in as early as 10 PCR cycles. The proposed method of PPi sensing offers interesting application potential in PCR-based rapid diagnostics for pathogenic agents and microbiological quality control.


Subject(s)
DNA, Bacterial/analysis , Diphosphates/chemistry , Escherichia coli/chemistry , Escherichia coli/cytology , Polymerase Chain Reaction/methods , Zinc/chemistry , Cell Count/methods
13.
Luminescence ; 28(3): 339-44, 2013.
Article in English | MEDLINE | ID: mdl-23426917

ABSTRACT

The interaction of ligands and drug molecules with protein is of major interest in drug pharmacokinetics and pharmacodynamics. In this study, we synthesized a novel thiosemicarbazone-based amphiphilic molecule for selective binding and detection of human serum albumin (HSA) with significant increase in fluorescence intensity. The compound 5-(octyloxy) naphthalene substituted salicylaldehyde thiosemicarbazone was designed to interact with site I of HSA. The weak fluorescence of the probes in aqueous solution showed a dramatic increase in fluorescence intensity upon binding with HSA, while the responses to various other proteins and enzymes were negligible under similar experimental conditions. Changes in fluorescence intensity and formation of a new emission maximum of the compound in the presence of HSA as well as an increase in steady-state anisotropy values reflected well the nature of binding and location of the probe inside the protein environment.


Subject(s)
Biosensing Techniques/methods , Serum Albumin/chemistry , Spectrometry, Fluorescence/methods , Thiosemicarbazones/chemistry , Humans , Molecular Structure , Protein Binding
14.
Inorg Chem ; 52(2): 743-52, 2013 Jan 18.
Article in English | MEDLINE | ID: mdl-23302031

ABSTRACT

We have synthesized a new indole functionalized rhodamine derivative L(1) which specifically binds to Cu(2+) in the presence of large excess of other competing ions with visually observable changes in their electronic and fluorescence spectral behavior. These spectral changes are significant enough in the NIR and visible region of the spectrum and thus enable naked eye detection. The receptor, L(1), could be employed as a resonance energy transfer (RET) based sensor for detection of Cu(2+) based on the process involving the donor indole and the acceptor Cu(2+) bound xanthene fragment. Studies reveal that L(1)-Cu complex is selectively and fully reversible in presence of sulfide anions. Further, fluorescence microscopic studies confirmed that the reagent L(1) could also be used as an imaging probe for detection of uptake of these ions in HeLa cells.


Subject(s)
Copper/chemistry , Fluorescent Dyes/chemistry , Rhodamines/chemistry , Sulfides/chemistry , Anions , Biological Assay , Cell Survival/drug effects , Coordination Complexes/chemistry , Coordination Complexes/pharmacology , Copper/metabolism , Fluorescence Resonance Energy Transfer/methods , Fluorescent Dyes/metabolism , Fluorescent Dyes/pharmacology , HeLa Cells , Humans , Hydrazines/chemistry , Ligands , Molecular Structure , Spectroscopy, Near-Infrared/methods , Sulfides/metabolism
15.
J Mater Chem B ; 1(20): 2612-2623, 2013 May 28.
Article in English | MEDLINE | ID: mdl-32260949

ABSTRACT

In this paper, we present a critical assessment of the therapeutic potential of low molecular weight pyridine-based synthetic amphiphiles based on structure-guided bactericidal activity and a rational evaluation of their cytotoxic potential. Fluorescence-based structure-function studies revealed that the amphiphiles were membrane-acting and displayed a hierarchical pattern of bactericidal activity, which could be correlated with their charge density and hydrophobicity. The membrane-targeting activity of the most potent cationic amphiphile (compound 6) was vindicated as it induced extensive membrane-disruption and dissipation of the transmembrane potential (ΔΨ) in pathogenic bacteria. At concentrations equivalent to the minimum inhibitory concentration (MIC) against the Gram-positive pathogen S. aureus MTCC 96, none of the amphiphiles exerted any cytotoxic effect on model human cell lines (HeLa, MCF-7 and HT-29). However, at elevated concentrations, a distinct gradation in the cytotoxic effect was manifested, which is probably accounted by the charge density and conformational flexibility of the amphiphiles. A viable therapeutic application of compound 6 is demonstrated in combinatorial assays, wherein the proclivity of the amphiphile to disrupt bacterial membranes at very low concentration is exploited to enhance the uptake and bactericidal efficacy of erythromycin against Gram-negative pathogenic bacteria.

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