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1.
Org Biomol Chem ; 2024 May 08.
Artigo em Inglês | MEDLINE | ID: mdl-38716563

RESUMO

The activation and utilization of challenging aliphatic alcohols like methanol and ethanol is a very appealing approach to synthesize valuable organic molecules. Utilization of methanol and ethanol as a coupling partner has emerged as a valuable alternative to synthesize industrially relevant N-heterocycles because they can be easily procured from renewable sources unlike other activated coupling partners which are expensive and also unstable. Herein, a mild and metal-free photocatalytic protocol to synthesize quinazolinones and more challenging benzothiadiazine-1,1-dioxides, which is unprecedented at room temperature, is demonstrated. This methodology showcased broad substrate scope and provided important N-heterocycles more efficiently than the transition metal-based high temperature protocols. An unexplored reactivity with allyl alcohol is observed following the developed protocol. A series of control experiments were carried out to understand the mechanism.

2.
Immunology ; 2024 Apr 02.
Artigo em Inglês | MEDLINE | ID: mdl-38566448

RESUMO

Ferroptosis, a necrotic, iron-dependent controlled cell death mechanism, is distinguished by the development of lipid peroxides to fatal proportions. Malignant tumours, influenced by iron to promote fast development, are vulnerable to ferroptosis. Based upon mounting evidence it has been observed that ferroptosis may be immunogenic and hence may complement immunotherapies. A new approach includes iron oxide-loaded nano-vaccines (IONVs), having supremacy for the traits of the tumour microenvironment (TME) to deliver specific antigens through improving the immunostimulatory capacity by molecular disintegration and reversible covalent bonds that target the tumour cells and induce ferroptosis. Apart from IONVs, another newer approach to induce ferroptosis in tumour cells is through oncolytic virus (OVs). One such oncolytic virus is the Newcastle Disease Virus (NDV), which can only multiply in cancer cells through the p53-SLC7A11-GPX4 pathway that leads to elevated levels of lipid peroxide and intracellular reactive oxygen species leading to the induction of ferroptosis that induce ferritinophagy.

3.
Med Oncol ; 41(5): 98, 2024 Mar 27.
Artigo em Inglês | MEDLINE | ID: mdl-38536512

RESUMO

Gynecological malignancies are most leading causes of death among women worldwide. The high prevalence of gynecologic malignancies remains significant, necessitating to turn the novel treatment approach like immunotherapy, wherein cancer cells are killed by the invasion of immune system. In recent year, immunotherapy has mostly an advanced treatment approach to repressing the tumor cells survival, proliferation, and invasion via the activation of immune systems. Moreover, various types of immune cells including T-cells, B-cells, and dendritic cells are associated with the immunotherapeutic strategy in cancer treatment. Although the significant role of T-cells against cancer is well established, while B-cells and dendritic cells also play an important role against different gynecological cancer by regulating the immune system. This review focuses on that arena and highlight the role of immune cells in the treatment of gynaecological cancer. Various immune cell-based anticancer therapies such as T-cell therapies, Adoptive Cellular transfer, B-cell therapies as well as approaches to Dendritic Cell therapies have been discussed in detail. Furthermore, the clinical settings and future avenues regarding immunotherapy on gynecological cancer have also been reviewed and illuminated in the recent study.


Assuntos
Neoplasias dos Genitais Femininos , Imunoterapia , Feminino , Humanos , Imunoterapia Adotiva , Neoplasias dos Genitais Femininos/terapia , Linfócitos T
4.
Med Oncol ; 41(4): 84, 2024 Mar 05.
Artigo em Inglês | MEDLINE | ID: mdl-38438564

RESUMO

In developing new cancer medications, attention has been focused on novel epigenetic medicines called histone deacetylase (HDAC) inhibitors. Our understanding of cancer behavior is being advanced by research on epigenetics, which also supplies new targets for improving the effectiveness of cancer therapy. Most recently published patents emphasize HDAC selective drugs and multitarget HDAC inhibitors. Though significant progress has been made in emerging HDAC selective antagonists, it is urgently necessary to find new HDAC blockers with novel zinc-binding analogues to avoid the undesirable pharmacological characteristics of hydroxamic acid. HDAC antagonists have lately been explored as a novel approach to treating various diseases, including cancer. The complicated terrain of HDAC inhibitor development is summarized in this article, starting with a discussion of the many HDAC isotypes and their involvement in cancer biology, followed by a discussion of the mechanisms of action of HDAC inhibitors, their current level of development, effect of miRNA, and their combination with immunotherapeutic.


Assuntos
MicroRNAs , Neoplasias , Humanos , Inibidores de Histona Desacetilases/farmacologia , Inibidores de Histona Desacetilases/uso terapêutico , MicroRNAs/genética , Terapia de Alvo Molecular , Epigênese Genética , Histona Desacetilases , Neoplasias/tratamento farmacológico , Neoplasias/genética
5.
J Math Biol ; 88(2): 14, 2024 01 05.
Artigo em Inglês | MEDLINE | ID: mdl-38180543

RESUMO

This study presents a new framework for obtaining personalized optimal treatment strategies targeting aberrant signaling pathways in esophageal cancer, such as the epidermal growth factor (EGF) and vascular endothelial growth factor (VEGF) signaling pathways. A new pharmacokinetic model is developed taking into account specific heterogeneities of these signaling mechanisms. The optimal therapies are designed to be obtained using a three step process. First, a finite-dimensional constrained optimization problem is solved to obtain the parameters of the pharmacokinetic model, using discrete patient data measurements. Next, a sensitivity analysis is carried out to determine which of the parameters are sensitive to the evolution of the variants of EGF receptors and VEGF receptors. Finally, a second optimal control problem is solved based on the sensitivity analysis results, using a modified pharmacokinetic model that incorporates two representative drugs Trastuzumab and Bevacizumab, targeting EGF and VEGF, respectively. Numerical results with the combination of the two drugs demonstrate the efficiency of the proposed framework.


Assuntos
Fator de Crescimento Epidérmico , Neoplasias Esofágicas , Humanos , Fator A de Crescimento do Endotélio Vascular , Transdução de Sinais , Neoplasias Esofágicas/tratamento farmacológico
6.
Cancer Invest ; 42(1): 44-62, 2024 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-38186047

RESUMO

Although not as well studied as the bacterial component of the human microbiota, the commensal fungi or mycobiota play important roles in maintaining our health by augmenting our immune system. This mycobiota is also associated with various fatal diseases like opportunistic mycoses, and even cancer, with different cancers having respective type-specific mycobiota. The different fungal species which comprise these different intratumoral mycobiota play important roles in cancer progression. The aim of this review paper is to decipher the association between mycobiota and cancer, and shed light on new avenues in cancer diagnosis, and the development of new anti-cancer therapeutics.


Assuntos
Micoses , Neoplasias , Humanos , Fungos , Neoplasias/diagnóstico , Neoplasias/tratamento farmacológico
7.
Mol Neurobiol ; 61(4): 1873-1891, 2024 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-37801205

RESUMO

Multiple genetic, environmental, and immunological variables cause neuropsychiatric disorders (NPDs). The induced inflammatory immune response is also connected to the severity and treatment outcomes of various NPDs. These reactions also significantly impact numerous brain functions such as GABAergic signaling and neurotransmitter synthesis through inflammatory cytokines and chemokines. Chalcones (1,3-diaryl-2-propen-1-ones) and their heterocyclic counterparts are flavonoids with various biological characteristics including anti-inflammatory activity. Several pure chalcones have been clinically authorized or studied in humans. Chalcones are favored for their diagnostic and therapeutic efficacy in neuroinflammation due to their tiny molecular size, easy manufacturing, and flexibility for changes to adjust lipophilicity ideal for BBB penetrability. These compounds reached an acceptable plasma concentration and were well-tolerated in clinical testing. As a result, they are attracting increasing attention from scientists. However, chalcones' therapeutic potential remains largely untapped. This paper is aimed at highlighting the causes of neuroinflammation, more potent chalcone congeners, their mechanisms of action, and relevant structure-activity relationships.


Assuntos
Chalcona , Chalconas , Humanos , Chalcona/farmacologia , Chalconas/farmacologia , Doenças Neuroinflamatórias , Relação Estrutura-Atividade , Flavonoides/farmacologia
8.
Artigo em Inglês | MEDLINE | ID: mdl-37982888

RESUMO

In an uncontrolled inflammatory environment, the complex process of lung carcinogenesis occurs. Lung cancer remains the leading cause of cancer-related mortality worldwide. The average 5-year survival rate is still low despite significant advancements in our knowledge of lung carcinogenesis and the development of innovative therapies in recent decades. Research on adjuvant treatment, lung carcinogenesis pathways, and possible prognostic indicators has to be refocused using an innovative approach. The majority of lung cancers are discovered at an advanced stage when there is little chance of recovery. It has grown in popularity in recent years to supplement already available chemotherapeutic therapies with adjuvant herbal medications, which may lessen toxicity and adverse effects without sacrificing therapeutic efficiency. One such prospective contender is curcumin. In-depth research has been done on curcumin as a multi-target anti-tumor and anti-inflammatory molecule. A pharmacologically active polyphenol produced from turmeric is called curcumin. Over the past few decades, curcumin's therapeutic potential has been thoroughly studied, and data indicate that curcumin may play a part in a variety of biological processes, most notably its potent anticancer activity. Being a pleiotropic chemical, curcumin regulates a variety of molecules that are key players in many cell signaling pathways. It has been shown to stifle transformation, restrain proliferation, and trigger apoptosis. Curcumin can reduce the development of non-small cell LC by downregulating Circular RNA hsa_circ_0007580, which in turn controls the expression of integrin subunit beta 1 by adsorbing miR-384. Nevertheless, despite all these advantages, curcumin's effectiveness is still restricted because of its weak bioavailability, poor absorption within the systemic circulation, and quick removal from the body. In an effort to overcome these constraints, scientists from all around the world are working to develop a synthetic and improved curcuminoid by appropriately altering the parent skeleton structurally. These curcuminoids will simultaneously improve the physicochemical properties and efficacy. This review presents evidence from the most recent clinical trials coupled with the molecular mechanisms of curcumin in LC. Curcumin as inhibitor of multiple signaling pathways expressed in lung cancer.

9.
Arch Virol ; 168(10): 264, 2023 Oct 03.
Artigo em Inglês | MEDLINE | ID: mdl-37787913

RESUMO

Japanese encephalitis virus (JEV) is the leading cause of viral encephalitis worldwide. The emergence of new genotypes of the virus and a high rate of mutation make it necessary to develop alternative treatment strategies against this deadly pathogen. Although the antiviral properties of Atropa belladonna and some of its active components, such as atropine and scopolamine, have been studied, the effect of another important component, hyoscyamine, against JEV infection has not yet been investigated. In this study, we investigated the antiviral effect of hyoscyamine against JEV and its immunomodulatory activity in embryonated chicken eggs. Pretreatment with hyoscyamine sulphate resulted in a significant decrease in the viral load in both chorioallantoic membrane (CAM) and brain tissues at 48 and 96 hours postinfection. In silico studies showed stable binding and interaction between hyoscyamine and non-structural protein 5 (NS5), suggesting that this could be the basis of its antiviral effect. Embryonated eggs pretreated with hyoscyamine sulphate showed upregulation of Toll-like receptor 3 (TLR3), TLR7, TLR8, interleukin 4 (IL-4), and IL-10 as well as interferons and regulatory factors. Hyoscyamine sulphate was also found to cause significant downregulation of TLR4. The potential use of hyoscyamine for controlling JEV replication and its dissemination to the brain suggest that it may be a promising therapy option against JEV in the future.


Assuntos
Vírus da Encefalite Japonesa (Espécie) , Hiosciamina , Animais , Galinhas , Atropina , Antivirais/farmacologia
10.
Chemistry ; 29(72): e202303135, 2023 Dec 22.
Artigo em Inglês | MEDLINE | ID: mdl-37867145

RESUMO

Metals play an important role in the structure and functions of various proteins. The combination of metal ions and peptides have been emerging as an attractive field to create advanced structures and biomaterials. Here, we are reporting the anion-influenced, silver ion coordinated diverse networks of designed short tripeptide 310 -helices with terminal pyridyl groups. The short peptides adopted classical right-handed, left-handed and 310 EL -helical conformations in the presence of different silver salts. The peptides have displayed conformational flexibility to accommodate different sizes and interactions of anions to yield a variety of metal-coordinated networks. The complexes of metal ions and peptides have shown different porous networks, right- and left-handed helical polymers, transformation of helix into superhelix and 2 : 2 metal-peptide macrocycles. Further, the metal-peptide crystals with inherent dipoles of helical peptides gave striking second harmonic generation response. The optical energy upconversion from NIR to red and green light is demonstrated. Overall, we have shown the utilization of short 310 -helices for the construction of diverse metal-coordinated helical networks and notable non-linear optical effects.


Assuntos
Peptídeos , Prata , Peptídeos/química , Conformação Molecular , Ânions
11.
Front Microbiol ; 14: 1200816, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-37720143

RESUMO

Cyanobacterial blooms pose a serious threat to water quality and human health due to the production of the potent hepatotoxin microcystin. In microcystin-producing strains of the widespread genus Microcystis, the toxin is largely constitutively produced, but there are fluctuations between the cellular and extracellular pool and between free microcystin and protein-bound microcystin. Here we addressed the question of how different temperatures affect the growth and temporal dynamics of secondary metabolite production in the strain Microcystis aeruginosa PCC7806 and its microcystin-deficient ΔmcyB mutant. While the wild-type strain showed pronounced growth advantages at 20°C, 30°C, and 35°C, respectively, the ΔmcyB mutant was superior at 25°C. We further show that short-term incubations at 25°C-35°C result in lower amounts of freely soluble microcystin than incubations at 20°C and that microcystin congener ratios differ at the different temperatures. Subsequent assessment of the protein-bound microcystin pool by dot blot analysis and subcellular localization of microcystin using immunofluorescence microscopy showed re-localization of microcystin into the protein-bound pool combined with an enhanced condensation at the cytoplasmic membrane at temperatures above 25°C. This temperature threshold also applies to the condensate formation of the carbon-fixing enzyme RubisCO thereby likely contributing to reciprocal growth advantages of wild type and ΔmcyB mutant at 20°C and 25°C. We discuss these findings in the context of the environmental success of Microcystis at higher temperatures.

12.
ACS Chem Neurosci ; 14(18): 3398-3408, 2023 09 20.
Artigo em Inglês | MEDLINE | ID: mdl-37656905

RESUMO

The recent approval of antibody-based therapy for targeting the clearance of amyloid plaques fuels the research in designing small molecules and peptide inhibitors to target the aggregation of Aß-peptides. Here, we report that the 15-residue ααγ-hybrid peptide not only inhibits the aggregation of soluble Aß42 into fibrils but also disintegrates the aggregated Aß42 fibrils into smaller assemblies. Further, the hybrid peptide completely rescues neuronal cells from the toxicity of Aß42 at equimolar concentrations. The shorter 10- and 12-mer peptides showed weak aggregation inhibition activity, while the fully hydrophobic 15-mer ααγ-hybrid peptide analogue showed no aggregation inhibition activity. Further, the 15-mer ααγ-hybrid peptide showed resistance against trypsin digestion and also nontoxic to the neuronal cells. The CD revealed that the peptide upon interaction induces a helix-type conformation in the Aß42. This is in sharp contrast to the ß-sheet conformation of Aß42 upon incubation. The two-dimensional-NMR (2D-NMR) analysis revealed a large perturbation in the chemical shifts of residues at the N-terminus. The presence of 15-mer peptide at an equimolar concentration of Aß42 showed less tendency for aggregation and also exhibited nontoxicity to the neuronal cells. The results reported here may be useful in designing new therapeutics for Alzheimer's disease.


Assuntos
Doença de Alzheimer , Peptídeos , Humanos , Angiotensina II , Citoesqueleto , Cinética
13.
Spine Deform ; 11(6): 1495-1501, 2023 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-37525061

RESUMO

PURPOSE: Circumferential minimally invasive scoliosis surgeries are often staged, wherein anterior and/or lateral lumbar interbody fusion is followed by percutaneous posterior fixation days later. This study examines the impact on outcomes when posterior augmentation was delayed due to unexpected medical issues following the first stage, anterolateral procedure. METHODS: A retrospective review was conducted of all patients undergoing minimally invasive circumferential deformity corrections from 2006 to 2019. Patients in whom planned posterior fixation was postponed due to medical necessity or safety concerns were identified. Perioperative surgical metrics and radiographic parameters were collected. RESULTS: Three of the six patients initially scheduled for circumferential fusion never underwent posterior augmentation due to symptomatic improvement (2.3, 5, and 10.7 years of follow-up). The other three underwent posterior fixation once medically optimized after an average interval of 4.7 months (range 3.2-7.8 months) due to persistent symptoms. It was also observed that the average coronal malalignment in the postoperative period was 5.1 cm in the group requiring further fixation and only 1.6 cm in the group which did not. CONCLUSION: In select cases, the indirect decompression and stability conferred by minimally invasive anterolateral arthrodesis alone may afford adequate pain relief to delay or even avoid posterior fixation in patients with adult spinal deformity.

14.
Med Chem ; 19(10): 960-985, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-37424341

RESUMO

In the recent era, developments in the field of bio-inorganic chemistry have improved interest in Schiff base complexes (imine scaffolds) for their pharmacological excellence in different areas. Schiff bases are a kind of synthetic molecule that is synthesized by the condensation reaction between a 1o amine and a carbonyl compound. Imine derivatives are also acknowledged for their ability to form complexes with several metals. Due to their wide range of biological activities, they have acquired prominence in the therapeutic and pharmaceutical industries. Inorganic chemists have continued to be intrigued by the vast range of uses of these molecules. Many of them are also thermally stable and have structural flexibility. Some of these chemicals have been discovered to be beneficial as clinical diagnostic agents as well as chemotherapeutic agents. Because of the flexibility of the reactions, these complexes have a wide range of characteristics and applications in biological systems. Anti-neoplastic activity is one of them. This review attempts to draw attention to the most notable examples of these novel compounds, which have excellent anticancer activity against different cancers. The synthetic scheme of these scaffolds, their metal complexes, and the explanation of their anticancer mechanism reported in this paper lead the researchers to design and synthesize more target-specific Schiff base congeners with little or no side effects in the future.

15.
Anal Chem ; 95(29): 11028-11036, 2023 Jul 25.
Artigo em Inglês | MEDLINE | ID: mdl-37428180

RESUMO

With the introduction of ultrahigh efficiency columns and fast separations, the need to eliminate peak deformation contributed by the instrument must be effectively solved. Herein, we develop a robust framework to automate deconvolution and minimize its artifacts, such as negative dips, wild noise oscillations, and ringing, by combining regularized deconvolution and Perona-Malik (PM) anisotropic diffusion methods. A asymmetric generalized normal (AGN) function is proposed to model the instrumental response for the first time. With no-column data at various flow rates, the interior point optimization algorithm extracts the parameters describing instrumental distortion. The column-only chromatogram was reconstructed using the Tikhonov regularization technique with minimal instrumental distortion. For illustration, four different chromatography systems are used in fast chiral and achiral separations with 2.1 and 4.6 mm i.d. columns. Ordinary HPLC data can approach highly optimized UHPLC data. Similarly, in fast HPLC-circular dichroism (CD) detection, 8000 plates were gained for a fast chiral separation. Moment analysis of deconvolved peaks confirms correction of the center of mass, variance, skew, and kurtosis. This approach can be easily integrated and used with virtually any separation and detection system to provide enhanced analytical data.

16.
Mol Neurobiol ; 60(10): 5987-6000, 2023 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-37391647

RESUMO

All biological tissues and bodily fluids include the autacoid adenosine. The P1 class of purinergic receptors includes adenosine receptors. Four distinct G-protein-coupled receptors on the cellular membrane mediate the effects of adenosine, whose cytoplasmic content is regulated by producing/degrading enzymes and nucleoside transporters. A2A receptor has received a great deal of attention in recent years because it has a wide range of potential therapeutic uses. A2B and, more significantly, A2A receptors regulate numerous physiological mechanisms in the central nervous system (CNS). The inferior targetability of A2B receptors towards adenosine points that they might portray a promising medicinal target since they are triggered only under pharmacological circumstances (when adenosine levels rise up to micromolar concentrations). The accessibility of specific ligands for A2B receptors would permit the exploration of such a theory. A2A receptors mediate both potentially neurotoxic and neuroprotective actions. Hence, it is debatable to what extent they play a role in neurodegenerative illnesses. However, A2A receptor blockers have demonstrated clear antiparkinsonian consequences, and a significant attraction exists in the role of A2A receptors in other neurodegenerative disorders. Amyloid peptide extracellular accumulation and tau hyperphosphorylation are the pathogenic components of AD that lead to neuronal cell death, cognitive impairment, and memory loss. Interestingly, in vitro and in vivo research has shown that A2A adenosine receptor antagonists may block each of these clinical symptoms, offering a crucial new approach to combat a condition for which, regrettably, only symptomatic medications are currently available. At least two requirements must be met to determine whether such receptors are a target for diseases of the CNS: a complete understanding of the mechanisms governing A2A-dependent processes and the availability of ligands that can distinguish between the various receptor populations. This review concisely summarises the biological effects mediated by A2A adenosine receptors in neurodegenerative disorders and discusses the chemical characteristics of A2A adenosine receptor antagonists undergoing clinical trials. Selective A2A receptor blocker against neurodegenerative disorders.


Assuntos
Adenosina , Doenças Neurodegenerativas , Humanos , Adenosina/farmacologia , Receptor A2A de Adenosina/metabolismo , Ligantes , Doenças Neurodegenerativas/tratamento farmacológico , Antagonistas de Receptores Purinérgicos P1/uso terapêutico , Receptores Purinérgicos P1
17.
Indian J Pharmacol ; 55(2): 97-107, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-37313935

RESUMO

OBJECTIVES: Colon carcinoma stands as the most familiar malignancy throughout across the globe. Raptinal induce apoptosis through the alteration of cellular events. Thus, in the present investigation, the anticancer activity of raptinal counter to 1,2-dimethylhydrazine (DMH) persuaded colon carcinoma has been evaluated through both in vivo and in vitro systems. MATERIALS AND METHODS: The pharmacophore analysis demonstrated the binding efficacy of raptinal with the apoptotic proteins. The chemotherapeutic activity of raptinal was examined through HT-29 human colorectal cancer (CRC) cell line as well as DMH persuaded CRC in the rat model. The cytotoxicity analysis, flow cytometry, and DAPI analysis have been carried out on HT-29 cell line through in vitro assessment. The colon carcinoma has been induced through DMH administration and subsequently Dextran sulfate sodium treatment in male Wistar rats. After 18 weeks of raptinal treatment, the colon tissues have been investigated for aberrant crypt foci (ACF) count, antioxidant status, histology, immunohistochemical assessment, and apoptotic analysis. RESULTS: The raptinal therapy on HT-29 cells demonstrated a substantial % of early apoptosis followed by G0 and G1 phase arrest, which subsequently led to apoptosis. Furthermore, it inhibits ACF development with improved colonic abrasions and structural integrity of colonic mucosa with increased levels of antioxidants, proapoptotic biomarkers including p53, caspase-3, Bax and downstream effects of Bcl-2, tumor necrosis factor (TNF)-α, and interleukin (IL)-6 mutation. CONCLUSIONS: These findings indicate the raptinal effectively reduces colon cancer by inducing apoptosis through p53/Bcl2/Bax/caspase-3 pathway and suppressing IL-6, TNF-mediated chronic inflammation in the colon cancer microenvironment.


Assuntos
Carcinoma , Neoplasias do Colo , Humanos , Masculino , Animais , Ratos , Ratos Wistar , 1,2-Dimetilidrazina/toxicidade , Proteína Supressora de Tumor p53 , Proteína X Associada a bcl-2 , Caspase 3 , Neoplasias do Colo/induzido quimicamente , Neoplasias do Colo/tratamento farmacológico , Antioxidantes , Microambiente Tumoral
18.
J Phys Condens Matter ; 35(35)2023 Jun 08.
Artigo em Inglês | MEDLINE | ID: mdl-37192633

RESUMO

In this work, we investigate the behavior of interacting electrons in a Su-Schrieffer-Heeger quantum ring, threaded by an Aharonov-Bohm (AB) fluxφ, within a tight-binding framework. The site energies of the ring follow the Aubry-Andre-Harper (AAH) pattern, and, depending on the specific arrangement of neighboring site energies two different configurations, namely, non-staggered and staggered, are taken into account. The electron-electron (e-e) interaction is incorporated through the well-known Hubbard form and the results are computed within the mean-field (MF) approximation. Due to AB fluxφ, a non-decaying charge current is established in the ring, and its characteristics are critically studied in terms of the Hubbard interaction, AAH modulation, and hopping dimerization. Several unusual phenomena are observed under different input conditions, that might be useful to analyze the properties of interacting electrons in similar kinds of other fascinating quasi-crystals in the presence of additional correlation in hopping integrals. A comparison between exact and MF results is given, for the sake of completeness of our analysis.

19.
Chemistry ; 29(42): e202300479, 2023 Jul 26.
Artigo em Inglês | MEDLINE | ID: mdl-37199015

RESUMO

Development of miniaturized lab-on-chip devices for the detection of rapid and specific small molecule-protein binding interactions at very low concentrations holds significant importance in drug discovery and biomedical applications. Here, the label-free detection of small molecule-protein interactions is reported on the surface functionalizable nanotubes of α,γ-hybrid peptide helical foldamers using nanoscale capacitance and impedance spectroscopy. The 12-helix conformation of the α,γ-hybrid peptide observed in the single crystals, self-assembled into nanotubes in an aqueous environment with exposed cysteine thiols for small molecule conjugation. The binding of streptavidin to the covalently linked biotin on the surface of nanotubes was detected at the picomolar concentrations. No change in the capacitance and impedance were observed in the absence of either immobilized biotin or protein streptavidin. The functionalizable hybrid peptide nanotubes reported here pave the way for the label-free detection of various small molecule protein interactions at very low concentrations.


Assuntos
Biotina , Nanotubos , Estreptavidina/química , Biotina/química , Nanotubos/química , Peptídeos/química , Proteínas
20.
Dalton Trans ; 52(42): 15394-15411, 2023 Oct 31.
Artigo em Inglês | MEDLINE | ID: mdl-37203345

RESUMO

A series of organometallic Re(I)(L)(CO)3Br complexes with 4'-substituted terpyridine ligands (L) has been synthesised as electrocatalysts for CO2 reduction. The complexes' spectroscopic characterisation and computationally optimised geometry demonstrate a facial geometry around Re(I) with three cis COs and the terpyridine ligand coordinating in a bidentate mode. The effect of substitution on the 4'-position of terpyridine (Re1-5) on CO2 electroreduction was investigated and compared with a known Lehn-type catalyst, Re(I)(bpy)(CO)3Br (Re7). All complexes catalyse CO evolution in homogeneous organic media at moderate overpotentials (0.75-0.95 V) with faradaic yields of 62-98%. The electrochemical catalytic activity was further evaluated in the presence of three Brønsted acids to demonstrate the influence of the pKa of the proton sources. The TDDFT and ultrafast transient absorption spectroscopy (TAS) studies showed combined charge transfer bands of ILCT and MLCT. Amongst the series, the Re-complex containing a ferrocenyl-substituted terpyridine ligand (Re5) shows an additional intra-ligand charge transfer band and was probed using UV-Vis spectroelectrochemistry.

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