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1.
J Phys Chem Lett ; 15(11): 3078-3088, 2024 Mar 21.
Artigo em Inglês | MEDLINE | ID: mdl-38467015

RESUMO

A biomimetic cell-based carrier system based on monocyte membranes and liposomes has been designed to create a hybrid "Monocyte-LP" which inherits the surface antigens of the monocytes along with the drug encapsulation property of the liposome. Förster resonance energy transfer (FRET) and polarization gated anisotropy measurements show the stiffness of the vesicles obtained from monocyte membranes (Mons), phosphatidylcholine membranes (LP), and Monocyte-LP to follow an increasing order of Mons > Monocyte-LP > LP. The dynamics of interface bound water molecules plays a key role in the elasticity of the vesicles, which in turn imparts higher delivery efficacy to the hybrid Monocyte-LP for a model anticancer drug doxorubicin than the other two vesicles, indicating a critical balance between flexibility and rigidity for an efficient cellular uptake. The present work provides insight on the influence of elasticity of delivery vehicles for enhanced drug delivery.


Assuntos
Antineoplásicos , Lipossomos , Lipossomos/metabolismo , Monócitos/metabolismo , Doxorrubicina , Sistemas de Liberação de Medicamentos
2.
Chemphyschem ; 25(2): e202300635, 2024 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-37936318

RESUMO

Liposomes of a cationic lipid dioctadecyldimethylammonium bromide (DODAB) are efficient nanocarriers of nucleic acids. Incorporation of a neutral lipid monoolein (MO) in excess (xMO >0.5) changes the lamellar organization of DODAB liposomes into non-lamellar inverted structures of DODAB/MO liposomes facilitating nucleic acid delivery to cells. Photoexcitation of 8-hydroxypyrene-1,3,6-trisulfonic acid (HPTS), a photoacid, initiates an excited state proton transfer (ESPT) reaction in its protonated form (ROH*) generating the deprotonated anionic form (RO- *). The fluorescence intensity ratio (IROH* /IRO-* ) of these two forms is governed by the ESPT dynamics, and increases with increasing MO content (xMO ) in the cationic liposomes of DODAB. Transition from lamellar organization of DODAB liposomes into non-lamellar inverted structures of DODAB/MO liposomes, due to incorporation of MO (xMO ~0.7), is manifested by a significant increase of ESPT time (τPT ) and the time constant of wobbling motion (τW ) of HPTS. Thus, the lamellar organizations of DODAB or DODAB-rich (xMO 0.2) liposomes and the non-lamellar organizations of MO-rich (xMO ~0.7) liposomes are recognized by significantly different excited state dynamics of the photoacid.


Assuntos
Lipossomos , Compostos de Amônio Quaternário , Lipossomos/química , Compostos de Amônio Quaternário/química
3.
J Phys Chem B ; 127(15): 3534-3542, 2023 04 20.
Artigo em Inglês | MEDLINE | ID: mdl-37036757

RESUMO

Epigenetic dysregulation including DNA methylation and histone modifications is being increasingly recognized as a promising biomarker for the diagnosis and prognosis of cancer. Herein, we devised a label-free analytical toolbox comprising IR, UV-vis, CD spectroscopy, and cyclic voltammetry, which is capable to differentiate significantly hyper-methylated breast cancer chromosomes from the normal breast epithelial counterparts.


Assuntos
Neoplasias da Mama , Humanos , Feminino , Neoplasias da Mama/genética , Epigênese Genética , Metilação de DNA , Biomarcadores , Cromossomos
4.
Spectrochim Acta A Mol Biomol Spectrosc ; 291: 122313, 2023 Apr 15.
Artigo em Inglês | MEDLINE | ID: mdl-36628863

RESUMO

A novel benzo[a]phenoxazine-based fluorescent dye LV2 has been employed as a molecular reporter to probe recognition of a linker histone protein H1 by calf-thymus DNA (DNA). Fluorescence lifetime of LV2 buried in the globular domain of H1 (∼2.1 ns) or in the minor groove of DNA (∼0.93 ns) increases significantly to 2.65 ns upon interaction of the cationic protein with DNA indicating formation of the H1-DNA complex. The rotational relaxation time of the fluorophore buried in the globular domain of H1 increases significantly from 2.2 ns to 8.54 ns in the presence of DNA manifesting the recognition of H1 by DNA leading to formation of the H1-DNA complex. Molecular docking and molecular dynamics (MD) simulations have shown that binding of LV2 is energetically most favourable in the interface of the H1-DNA complex than in the globular domain of H1 or in the minor groove of DNA. As a consequence, orientational relaxation of the LV2 is significantly hindered in the protein-DNA interface compared to H1 or DNA giving rise to a much longer rotational relaxation time (8.54 ns) in the H1-DNA complex relative to that in pure H1 (2.2 ns) or DNA (5.7 ns). Thus, via a significant change of fluorescence lifetime and rotational relaxation time, the benzo[a]phenoxazine-based fluorescent dye buried within the globular domain of the cationic protein, or within the minor groove of DNA, reports on recognition of H1 by DNA.


Assuntos
DNA , Corantes Fluorescentes , Corantes Fluorescentes/química , Simulação de Acoplamento Molecular , DNA/química , Análise Espectral , Simulação de Dinâmica Molecular
5.
Mater Today Proc ; 80: 1846-1851, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-34178606

RESUMO

The current COVID-19 pandemic has increased the use of alcohol based hand sanitisers globally. These available alcohol based sanitisers cannot provide an antibacterial effect for an extended period of time, after the evaporation of ethanol. Hence, the need for a sanitiser with an anti-microbial activity combined with a long lasting effect is the need of the hour. In this study, we report the synthesis of a long lasting sanitiser from ozonated omega 9 fatty acid esters in an ethanolic medium. The formed vesicles made of the fatty acids have been characterized by DLS, Zeta potential, and time resolved fluorescence anisotropy studies. Ethanol although, provides an antibacterial effect, the effect is more pronounced in our prepared formulation owing to its high peroxide value that generates additional oxidative stress. Finally, this additional antimicrobial effect will have relevance in the current COVID-19 scenario in providing a long lasting hand sanitiser.

6.
Sci Rep ; 12(1): 18881, 2022 11 07.
Artigo em Inglês | MEDLINE | ID: mdl-36344591

RESUMO

Anti-microbial resistant infection is predicted to be alarming in upcoming years. In the present study, we proposed co-localization of two model drugs viz., rifampicin and benzothiazole used in anti-tuberculosis and anti-fungal agents respectively in a nanoscopic cationic micelle (cetyl triethyl ammonium bromide) with hydrodynamic diameter of 2.69 nm. Sterilization effect of the co-localized micellar formulation against a model multi-drug resistant bacterial strain viz., Methicillin resistant Staphylococcus aureus was also investigated. 99.88% decrease of bacterial growth in terms of colony forming unit was observed using the developed formulation. While Dynamic Light Scattering and Forsters Resonance Energy Transfer between benzothiazole and rifampicin show co-localization of the drugs in the nanoscopic micellar environment, analysis of time-resolved fluorescence decays by Infelta-Tachiya model and the probability distribution of the donor-acceptor distance fluctuations for 5 µM,10 µM and 15 µM acceptor concentrations confirm efficacy of the co-localization. Energy transfer efficiency and the donor acceptor distance are found to be 46% and 20.9 Å respectively. We have also used a detailed computational biology framework to rationalize the sterilization effect of our indigenous formulation. It has to be noted that the drugs used in our studies are not being used for their conventional indication. Rather the co-localization of the drugs in the micellar environment shows a completely different indication of their use in the remediation of multi-drug resistant bacteria revealing the re-purposing of the drugs for potential use in hospital-born multi-drug resistant bacterial infection.


Assuntos
Staphylococcus aureus Resistente à Meticilina , Rifampina/farmacologia , Farmacorresistência Bacteriana Múltipla , Micelas , Benzotiazóis/farmacologia , Antibacterianos/farmacologia , Testes de Sensibilidade Microbiana
7.
Biosens Bioelectron ; 218: 114764, 2022 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-36206669

RESUMO

Urinary bladder cancer (UBC) is one of the most common cancers and has notoriously high risk of recurrence and mortality across the globe. Current clinical initial diagnostic approaches are either invasive or lacks sensitivity. In this study, an attempt has been made to invent a cost-effective, novel, portable diagnostic device based on the environmental sensitive fluorophores namely Nile Red (NR), Eosin Y (EY) and Rose Bengal (RB). They act as sensing agents for detecting volatile organic compounds (VOC) exclusively present in the urine sample of UBC patients and differentiate the UBC samples from the healthy control group. Upon exposure with a particular group of VOCs, a significant amount of increment in fluorescence intensities of NR, EY and RB were detected and recorded in our indigenously developed "NABIL" device. To check the performance of NABIL, the data collected from the device was compared with the conventional techniques by arranging a clinical trial with 21 healthy controls and 52 UBC patients. With the assistance of our analysis technique based on LabVIEW platform, very high sensitivity and accuracy from healthy controls have been achieved. For UBC patients, it shows impressive diagnostic results. In addition, depending on the sample processing mechanism, NABIL device can also reveal the grade of UBC and prognosis under treatment. Overall, this study contributes a novel, non-invasive, easy-to-use, inexpensive, real-time, accurate method for selectively UBC diagnosis, which can be useful for personalized care/diagnosis and postoperative surveillance, resulting in saving more lives.


Assuntos
Técnicas Biossensoriais , Neoplasias da Bexiga Urinária , Compostos Orgânicos Voláteis , Humanos , Biomarcadores , Biomarcadores Tumorais/urina , Amarelo de Eosina-(YS) , Rosa Bengala , Neoplasias da Bexiga Urinária/diagnóstico , Neoplasias da Bexiga Urinária/urina
8.
J Phys Chem Lett ; 13(36): 8564-8572, 2022 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-36069730

RESUMO

Cancer cells secrete extracellular vesicles (EVs) covered with a carbohydrate polymer, hyaluronan (HA), linked to tumor malignancy. Herein, we have unravelled the contour lengths of HA on a single cancer cell-derived EV surface using single-molecule force spectroscopy (SMFS), which divulges the presence of low molecular weight HA (LMW-HA < 200 kDa). We also discovered that these LMW-HA-EVs are significantly more elastic than the normal cell-derived EVs. This intrinsic elasticity of cancer EVs could be directly allied to the LMW-HA abundance and associated labile water network on EV surface as revealed by correlative SMFS, hydration dynamics with fluorescence spectroscopy, and molecular dynamics simulations. This method emerges as a molecular biosensor of the cancer microenvironment.


Assuntos
Vesículas Extracelulares , Neoplasias , Humanos , Ácido Hialurônico/química , Peso Molecular , Microambiente Tumoral
9.
Front Chem ; 10: 978668, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-36118312

RESUMO

Enzyme function can be altered via modification of its amino acid residues, side chains and large-scale domain modifications. Herein, we have addressed the role of residue modification in catalytic activity and molecular recognition of an enzyme alpha-chymotrypsin (CHT) in presence of a covalent cross-linker formalin. Enzyme assay reveals reduced catalytic activity upon increased formalin concentration. Polarization gated anisotropy studies of a fluorophore 8-Anilino-1-naphthalenesulfonic acid (ANS) in CHT show a dip rise pattern in presence of formalin which is consistent with the generation of multiple ANS binding sites in the enzyme owing to modifications of its local amino acid residues. Molecular docking study on amino acid residue modifications in CHT also indicate towards the formation of multiple ANS binding site. The docking model also predicted no change in binding behavior for the substrate Ala-Ala-Phe-7-amido-4-methylcoumarin (AMC) at the active site upon formalin induced amino acid cross-linking.

10.
Phys Chem Chem Phys ; 24(10): 6176-6184, 2022 Mar 09.
Artigo em Inglês | MEDLINE | ID: mdl-35229087

RESUMO

The potentiality of Förster resonance energy transfer (FRET) for studying molecular interactions inside biological tissues with improved spatial (Angström) and temporal (picosecond) resolution is well established. On the other hand, the efficacy of diffuse reflectance spectroscopy (DRS) that uses optical radiation in order to determine physiological parameters including haemoglobin, and oxygen saturation is well known. Here we have made an attempt to combine diffuse reflectance spectroscopy (DRS) with picosecond-resolved FRET in order to show improvement in the exploration of molecular contacts in biological tissue models. We define the technique as ultrafast time-resolved diffuse reflectance spectroscopy (UTRDRS). The illuminated photon of the fluorophore from the surface of the tissue-mimicking layers carries the hidden information of the molecular contact. In order to investigate the validation of the Kubelka-Munk (KM) formulism for the developed UTRDRS technique in tissue phantoms, we have studied the propagation of incandescent and picosecond-laser light through several layers of cellulose membranes. While picosecond-resolved FRET in the diffuse reflected light confirms the hidden nano-contact (4.6 nm) of two different dye layers (8-anilino-1-naphthalenesulfonic acid and Nile blue), high-resolution optical microscopy on the cross-section of the layers reveals the proximity and contacts of the layers with limited spatial resolution (∼300 nm). We have also investigated two biologically relevant molecules, namely carboxyfluorescein and haemoglobin, in tissue phantom layers in order to show the efficacy of the UTRDRS technique. Overall, our studies based on UTRDRS in tissue mimicking layers may have potential applications in non-invasive biomedical diagnosis for patients suffering from skin diseases.


Assuntos
Transferência Ressonante de Energia de Fluorescência , Luz , Transferência Ressonante de Energia de Fluorescência/métodos , Corantes Fluorescentes , Hemoglobinas , Humanos , Análise Espectral
11.
Curr Drug Deliv ; 19(10): 991-1000, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35346006

RESUMO

The direct delivery of therapeutic molecules is generally inefficient and has several problems. Hence, nanomedicines with targeted and controlled delivery applications have been an exciting field of research for the past decade. In this regard, the adjustable properties of inorganic nanoparticles like particle size distribution, ability to change the targeting ligand to have a higher affinity towards the pathologic cell, and controlled delivery properties have made them indispensable for targeted drug delivery applications. Changing the ligand on the surface of the inorganic nanoparticle can direct different therapeutic molecules to different organs like the liver, spleen, kidney, bone, and even brain. However, while the other targeted nanomedicines are well-reported, the targeting of therapeutics to bone marrow cells is sparse in the literature. Hence, the administration of therapeutics for bone-related disorders, like bone metastases, leads to several problems, such as severe systemic toxicity and suboptimal efficacy. In this direction, we have shown our successful effort to functionalise a model inorganic nanoparticle (Fe2O3) by glutamate ligand which is reported to have a high affinity towards the NMDA receptors of the bone cells. We have performed spectroscopic studies to characterize the nano-hybrid. We have shown that the cargo or the Fe2O3 nanoparticle possesses the ability to generate photo-induced reactive oxygen species (ROS), thereby leading to a therapeutic opportunity for bone metastases. In addition, the nanoparticle also possesses the ability to generate enhanced ROS on X-ray irradiation, which may provide a new strategy for bone metastases and cancer therapy. Also, this paper reviews the advancement in the drug delivery applications of inorganic nanoparticles and highlights the crosstalk between the inorganic nanoparticles with the conjugated targeting ligand for efficient delivery applications.


Assuntos
Ferro , Nanopartículas , Medula Óssea , Sistemas de Liberação de Medicamentos/métodos , Ácido Glutâmico , Ligantes , Nanopartículas/química , Preparações Farmacêuticas , Espécies Reativas de Oxigênio , Raios X
12.
Chembiochem ; 23(9): e202200109, 2022 05 04.
Artigo em Inglês | MEDLINE | ID: mdl-35225409

RESUMO

Drug delivery to a target without adverse effects is one of the major criteria for clinical use. Herein, we have made an attempt to explore the delivery efficacy of SDS surfactant in a monomer and micellar stage during the delivery of the model drug, Toluidine Blue (TB) from the micellar cavity to DNA. Molecular recognition of pre-micellar SDS encapsulated TB with DNA occurs at a rate constant of k1 ∼652 s-1 . However, no significant release of encapsulated TB at micellar concentration was observed within the experimental time frame. This originated from the higher binding affinity of TB towards the nano-cavity of SDS at micellar concentration which does not allow the delivery of TB from the nano-cavity of SDS micelles to DNA. Thus, molecular recognition controls the extent of DNA recognition by TB which in turn modulates the rate of delivery of TB from SDS in a concentration-dependent manner.


Assuntos
DNA , Micelas , Genômica , Análise Espectral , Tensoativos
13.
Mon Not R Astron Soc ; 511(2): 1622-1636, 2022 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-35153618

RESUMO

We use the results of relativistic hydrodynamic simulations of jet-interstellar medium (ISM) interactions in a galaxy with a radio-loud AGN to quantify the extent of ionization in the central few kpcs of the gaseous galactic disc. We perform post-process radiative transfer of AGN radiation through the simulated gaseous jet-perturbed disc to estimate the extent of photo-ionization by the AGN with an incident luminosity of 1045 erg s-1. We also map the gas that is collisionally ionized due to shocks driven by the jet. The analysis was carried out for simulations with similar jet power (1045 erg s-1) but different jet orientations with respect to the gas disc. We find that the shocks from the jets can ionize a significant fraction (up to 33 [Formula: see text]) of dense gas ([Formula: see text]) in the disc, and that the jets clear out the central regions of gas for AGN radiation to penetrate to larger distances in the disc. Jets inclined towards the disc plane couple more strongly with the ISM and ionize a larger fraction of gas in the disc as compared to the vertical jet. However, similar to previous studies, we find that the AGN radiation is quickly absorbed by the outer layers of dense clouds in the disc, and is not able to substantially ionize the disc on a global scale. Thus, compared to jet-ISM interactions, we expect that photo-ionization by the AGN radiation only weakly affects the star-formation activity in the central regions of the galactic disc (≲ 1 kpc), although the jet-induced shocks can spread farther out.

14.
J Phys Chem B ; 126(3): 588-600, 2022 01 27.
Artigo em Inglês | MEDLINE | ID: mdl-35041417

RESUMO

Complexes of cationic liposomes with DNA have emerged as promising nonviral vectors for delivering genetic information into cells for gene therapy. Kinetics of the liposome/DNA complex (lipoplex) formation on a millisecond time scale are studied by monitoring time evolution of fluorescence of 8-anilino-1-naphthalene sulfonic acid (ANS) and ethidium bromide (EtBr) in a continuous flow microfluidic channel coupled to a fluorescence microscope. The formation of lipoplexes between calf thymus DNA and liposomes based on two novel cationic lipids (Lip1810 and Lip1814) are found to follow a two-step process with kinetic constants for the Lip1814/DNA complex (k1 = 1120-1383 s-1, k2 = 0.227-1.45 s-1) being significantly different from those (k1 = 68.53-98.5 s-1, k2 = 32.3-60.19 s-1) corresponding to formation of the Lip1810/DNA complex. The kinetic pathway leading to the formation of Lip1814/DNA complex is diffusion-controlled whereas the formation of Lip1810/DNA complex occurs by a conformational rearrangement-controlled pathway. The observed difference in the kinetics of lipoplex formation likely originates from different structures of the lipid/DNA complexes.


Assuntos
DNA , Microfluídica , Cátions/química , DNA/química , Lipídeos/química , Lipossomos/química , Plasmídeos , Transfecção
15.
ChemMedChem ; 17(14): e202100660, 2022 07 19.
Artigo em Inglês | MEDLINE | ID: mdl-35075815

RESUMO

This study explores a combined electrochemical and spectroscopic approach to investigate the degradation of bilirubin, a molecular marker of jaundice in humans using a biocompatible nanohybrid (citrate-functionalized Mn3 O4 nanohybrid; C-Mn3 O4 NH). The approach is aimed at the development of a facile theranostic tool for treatment, detection, and prognosis of jaundice. Linear sweep voltammetry (LSV) studies on bilirubin, C-Mn3 O4 NH, a model carrier protein, and its complex with bilirubin reveal the efficacy of the nanohybrid for both degradation and detection of bilirubin. Furthermore, spectroscopic studies depict that distal electron transfer to be the probable mechanism behind the observed bilirubin degradation in physiological milieu.


Assuntos
Icterícia , Medicina de Precisão , Bilirrubina , Biomarcadores , Técnicas Eletroquímicas , Humanos , Oxirredução
16.
ACS Phys Chem Au ; 2(3): 171-178, 2022 May 25.
Artigo em Inglês | MEDLINE | ID: mdl-36855571

RESUMO

We demonstrate experimental evidence of the effect of surface plasmon resonance of noble metal nanoparticles (NPs) on the activity of a well-known biomedicinal drug in the proximity of a semiconductor having a wide band gap for enhanced photodynamic therapy (PDT) efficacy. We have chosen riboflavin (Rf) (or vitamin B2) as a model photosensitizer, attached with ZnO NPs and further attached with gold (Au) NP-decorated ZnO to increase the efficiency. The synthesized nanohybrids are characterized with the help of different microscopic, optical spectroscopic, and density functional theory (DFT)-based techniques. The DFT and time-dependent DFT-based calculations validate the experimental findings. A detailed ultrafast spectroscopic study has been carried out further to study the excited-state charge dynamics in the interface of the nanohybrids. The occurrence of a Förster resonance energy transfer (FRET) between Rf and Au has been found to be the key reason for the increased efficiency in the Rf-ZnO-Au nanohybrid over the Rf-ZnO one. The dipolar coupling between Au and Rf in the Rf-ZnO-Au nanohybrid further facilitates the generation of reactive oxygen species (ROS) in comparison to Rf-ZnO under blue-light irradiation. The greater efficiency in ROS generation by the Rf-ZnO-Au nanohybrid has been utilized for antimicrobial action against methicillin-resistant S. aureus (MRSA). Overall, the present study highlights the dual sensitization for achieving enhanced electron injection efficiency in the Rf-ZnO-Au nanohybrid in order to use it as an antibacterial agent that could be translated in PDT.

17.
Int J Inj Contr Saf Promot ; 29(2): 160-181, 2022 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-34486925

RESUMO

In developing nations, road traffic crashes involving pedestrians have become a foremost worry. Presently, most of the road safety assessment projects and selection of interventions are still restricted to traditional methods that depend on historical crash data. However, in low and middle-income countries such as India, the availability, reliability, and accuracy of crash data are uncertain. Alternatively, Post Encroachment Time (PET) has added attention as a proximal indicator to examine pedestrian-vehicular potential crashes and address pedestrian risk under mixed traffic conditions. Hence, it will be meaningful to examine if the PET is a good substitute for pedestrian-vehicular crashes and if so, what built environment and pedestrian-level factors influence PET. In this background, the present study establishes a mathematical association between the average PET value of the urban road network level and actual crashes. Afterward, multiple linear regression models are developed to study the impact of the built environment, traffic parameters, and pedestrian-level attributes on PET. The outcomes indicate that vehicle speed, lack of enforcement, absence of traffic signal (for traffic as well as pedestrians), land use type, slum population, inadequate sight distance, pedestrian's state of crossing, and pedestrian's risky crossing behaviour substantially affect the average PET at road network-level.


Assuntos
Pedestres , Acidentes de Trânsito/prevenção & controle , Ambiente Construído , Humanos , Índia , Reprodutibilidade dos Testes , Segurança
18.
Accid Anal Prev ; 163: 106469, 2021 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-34773787

RESUMO

Pedestrian fatalities and injuries are a major public health burden in developing countries. In the safety literature, pedestrian crashes have been modelled predominately using single equation regression models, assuming a single underlying source of risk factors. In contrast, the fatal pedestrian crash counts at a site may be an outcome of multiple sources of risk factors, such as poor road infrastructure, land use type, traffic exposures, and operational parameters, site-specific socio-demographic characteristics, as well as pedestrians' poor risk perception and dangerous crossing behavior, which may be influenced by poor road infrastructure and lack of information, etc. However, these multiple sources are generally overlooked in traditional single equation crash prediction models. In this background, this study postulates, and demonstrates empirically, that the total fatal pedestrian crash counts at the urban road network level may arise from multiple simultaneous and interdependent sources of risk factors, rather than one. Each of these sources may distinctively contribute to the total observed crash count. Intersection-level crash data obtained from the "Kolkata Police", India, is utilized to demonstrate the present modelling methodology. The three-components mixture model and a joint econometric model are developed to predict fatal pedestrian crashes. The study outcomes indicate that the multiple-source risk models perform significantly better than the single equation regression model in terms of prediction ability and goodness-of-fit measures. Moreover, while the single equation model predicts total fatal crash counts for individual sites, the multiple risk source model predicts crash count proportions contributed by each source of risk factors and predicts crashes by a particular source.


Assuntos
Pedestres , Acidentes de Trânsito , Países em Desenvolvimento , Humanos , Polícia , Fatores de Risco
19.
ChemMedChem ; 16(24): 3739-3749, 2021 12 14.
Artigo em Inglês | MEDLINE | ID: mdl-34550644

RESUMO

Functionalized nanoparticles reveal new frontiers in therapeutics and diagnostics, simultaneously referred to as theranostics. Functionalization of an inorganic nanoparticle (NP) with an organic ligand determines the interaction of the functionalized NPs with various cellular components, leading to the desired therapeutic effect, while diminishing adverse side effects. Apart from the therapeutic effect of the nanoparticles, other physical properties of the organic-inorganic complex (nanohybrid) including fluorescence, X-ray or MRI contrast offer diagnosis of the anomalous target cell. In this study we functionalized Mn3 O4 NPs with organic citrate (C-Mn3 O4 ) and folic acid (FA-Mn3 O4 ) ligands and investigated their antimicrobial activities using Staphylococcus hominis as a model bacteria, which can be remediated through their membrane rupture. While high-resolution transmission microscopy (HR-TEM), XRD, DLS, absorbance and fluorescence spectroscopy were used for structural characterisation of the functionalised NPs, zeta potential measurements and temperature-dependent reactive oxygen speices (ROS) generation reveal their drug action. We used high-end density functional theory (DFT) calculations to rationalise the specificity of the drug action of the NPs. Picosecond-resolved FRET studies confirm the enhanced affinity of FA-Mn3 O4 to the bacteria relative to C-Mn3 O4 , leading to enhanced antimicrobial activity. We have shown that the functionalised nanoparticles offer significant X-ray contrast in in-vitro studies, indicating the FA-Mn3 O4 NPs to be a potential theranostic agent against bacterial infection.


Assuntos
Antibacterianos/farmacologia , Teoria da Densidade Funcional , Staphylococcus hominis/efeitos dos fármacos , Antibacterianos/química , Ácido Cítrico/química , Ácido Cítrico/farmacologia , Relação Dose-Resposta a Droga , Difusão Dinâmica da Luz , Ácido Fólico/química , Ácido Fólico/farmacologia , Compostos de Manganês/química , Compostos de Manganês/farmacologia , Testes de Sensibilidade Microbiana , Microscopia Eletrônica de Transmissão , Estrutura Molecular , Nanopartículas/química , Óxidos/química , Óxidos/farmacologia , Espectrometria de Fluorescência , Relação Estrutura-Atividade , Nanomedicina Teranóstica , Difração de Raios X
20.
Int J Biol Macromol ; 176: 137-144, 2021 Apr 15.
Artigo em Inglês | MEDLINE | ID: mdl-33548310

RESUMO

Human serum albumin (HSA) plays a pivotal role in drug release from its delivery vehicles such as cyclodextrins (CDs) by binding to the drugs. Here molecular recognition and binding of a drug mimic (CD1) to HSA have been explored in a microfluidic channel when CD1 is encapsulated in ß-cyclodextrin (ßCD) and heptakis(2,3,6-tri-O-methyl)-ß-cyclodextrin (TRIMEB), respectively, to investigate whether change of the host vehicle modulate the rate of drug binding to the serum protein. Molecular recognition of ßCD encapsulated CD1 by HSA occurs by the conformational selection fit mechanism leading to rapid binding of CD1 to HSA (k1 ~ 700 s-11) when the ßCD/CD1 complex interacts with HSA. In contrary, HSA recognizes CD1 encapsulated in TRIMEB by an induced fit mechanism leading to a significantly slower binding rate (k1 ~ 20.8 s-1) of the drug mimic to the protein. Thus molecular recognition controls the rate of HSA binding by CD1 which in turn modulates the rate of delivery of the drug mimic from its macrocyclic hosts. The remarkable change in the molecular recognition pathway of CD1 by HSA, upon change of the host from ßCD to TRIMEB, originates from significantly different conformational flexibility of the host/drug mimic complexes.


Assuntos
Albumina Sérica Humana/química , Biomimética , Configuração de Carboidratos , Ciclodextrinas/química , Liberação Controlada de Fármacos , Polarização de Fluorescência , Humanos , Cinética , Microfluídica , Modelos Moleculares , Simulação de Dinâmica Molecular , Ligação Proteica , Conformação Proteica , Albumina Sérica Humana/metabolismo , Espectrometria de Fluorescência , beta-Ciclodextrinas/química
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