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1.
J Nanosci Nanotechnol ; 20(2): 819-827, 2020 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-31383077

RESUMO

Synthesis of pure Hafnium Oxide (HfO2), and HfO2 doped with Gadolinium (1, 3, 5 and 7 mol%) nanoparticles (NPs) had been carried out by Precipitation and co-precipitation method using the precursor solution of Hafnium (IV) chloride (HfCl4) and Gadolinium(III) chloride hexahydrate (GdCl3·6H2O) with Sodium hydroxide (NaOH) which was dissolved in deionized water. The synthesized compound was characterized and analyzed by X-ray diffraction (XRD), Field emission scanning electron microscopy (FESEM), Energy dispersive X-ray analysis (EDX), UV-visible spectrophotometer, Photoluminescence (PL), Fourier Transform infrared spectroscopy (FTIR) and Raman spectroscopy. The result from X-ray diffraction showed that the Gd3+ concentration for 7 mol% had attended directly crystalline phase of Cubic HfO2 structure. Morphology and element analysis of the samples were analyzed using FESEM and EDX, which indicated cluster formation, fluffy and voids with highly agglomerated particles and EDX exhibited no extra peaks with other than constituent elements present in extrinsic HfO2. From UV Spectra it was observed that the optical band gap of both Intrinsic and extrinsic of HfO2 NPs were found to be 5.74 eV, 3.62 eV, 3.69 eV, 3.78 eV and 4.19 eV. The Photoluminescence Spectra showed the 313 nm emission line which might be due to 6P7/2→8S7/2 transition and the Raman Spectra clearly represented the monoclinic structure by showing the presence of Ag and Bg Modes and cubic structure because of the presence of F2g mode.

2.
J Fluoresc ; 29(3): 803-812, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-31187405

RESUMO

With the emerging trend of personalized cancer treatment, there is a need to develop noninvasive/minimally invasive techniques for treatment monitoring. In this regard, in this work fluorescence analysis of blood plasma of breast cancer patients has been used for the evaluation of response to treatment. This approach delivers information not only about the change in biochemical constituents but also about the altered metabolic pathway. Spectral deconvolution method is employed to compute the fluorescence intensity, peak wavelength, and full-width half maxima for different endogenous fluorophores. The fluorescence measurements were made on blood plasma collected from 10 normal subjects, 10 pre-treated cancer patients, and 10 post-treated patients. Besides, variations in relative concentration of tryptophan, collagen, NADH, and FAD, peak shifts and broadening of peaks are observed for tryptophan, NADH, and FAD, in blood plasma of pre-treated cancer patients indicating both biochemical and microenvironmental changes at cellular level. Further, the spectral profile of blood plasma of post-treated patients found to be similar to blood plasma of normal subjects. Linear discriminant analysis showed that pre-treated and post-treated breast cancer is discriminated with a sensitivity and specificity of 100% and 100% respectively.

3.
Mol Pharm ; 16(2): 669-681, 2019 02 04.
Artigo em Inglês | MEDLINE | ID: mdl-30601011

RESUMO

In this present study on understanding the taxol (PTX) binding interaction mechanism in both the ß-tubulin and bovine serum albumin (BSA) molecule, various optical spectroscopy and computational techniques were used. The fluorescence steady-state emission spectroscopy result suggests that there is a static quenching mechanism of the PTX drug in both ß-tubulin and BSA, and further time-resolved emission spectroscopy studies confirm that the quenching mechanism exists. The excitation-emission matrix (EEM), Fourier transform infrared, and resonance light scattering spectra (FT-IR) confirm that there are structural changes in both the BSA and ß-tubulin molecule during the binding process of PTX. The molecular docking studies revealed the PTX binding information in BSA, ß-tubulin, and modeled ß-tubulin and the best binding pose to further subject the molecular dynamics simulation, and this study confirms the stability of PTX in the protein complex during the simulation. Density functional theory (DFT) calculations were performed between the free PTX drug and PTX drug (single point) in the protein molecule active site region to understand the internal stability.

4.
J Chem Inf Model ; 2018 Nov 27.
Artigo em Inglês | MEDLINE | ID: mdl-30481010

RESUMO

In this present study focus that determination of biologically significant N-Acetylneuraminic acid (NANA) drug binding interaction mechanism between bovine serum albumin (BSA) and human α-1 acid glycoprotein (HAG) using various optical spectroscopy and computational methods. The steady state fluorescence spectroscopy result suggests that the fluorescence intensity of BSA, HAG was quenched by NANA drug in a static mode of quenching. Further time- resolved emission spectroscopy measurements confirm that mode of quenching mechanism of NANA drug in BSA and HAG system. The FT-IR, excitation -emission matrix analysis confirms the presence of NANA drug in HAG, BSA system and fluorescence resonance energy transfer analysis calculation shows that the NANA drug energy transfer between HAG, BSA system. The molecular docking result shows good binding affinity in both protein complex and further molecular dynamics simulations and charge distribution analysis were performed to understand more insight binding interaction mechanism of NANA drug in HAG, BSA complex.

5.
Luminescence ; 33(4): 731-741, 2018 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-29578306

RESUMO

In this study the interaction mechanism between newly synthesized 4-(3-acetyl-5-(acetylamino)-2-methyl-2, 3-dihydro-1,3,4-thiadiazole-2-yl) phenyl benzoate (thiadiazole derivative) anticancer active drug with calf thymus DNA was investigated by using various optical spectroscopy techniques along with computational technique. The absorption spectrum shows a clear shift in the lower wavelength region, which may be due to strong hypochromic effect in the ctDNA and the drug. The results of steady state fluorescence spectroscopy show that there is static quenching occurring while increasing the thiadiazole drug concentration in the ethidium bromide-ctDNA system. Also the binding constant (K), thermo dynamical parameters of enthalpy change (ΔH°), entropy change (ΔS°) Gibbs free energy change (ΔG°) were calculated at different temperature (293 K, 298 K) and the results are in good agreement with theoretically calculated MMGBSA binding analysis. Time resolved emission spectroscopy analysis clearly explains the thiadiazole derivative competitive intercalation in the ethidium bromide-ctDNA system. Further, molecular docking studies was carried out to understand the hydrogen bonding and hydrophobic interaction between ctDNA and thiadiazole derivative molecule. In addition the docking and molecular dynamics charge distribution analysis was done to understand the internal stability of thiadiazole derivative drug binding sites of ctDNA. The global reactivity of thiadiazole derivative such as electronegativity, electrophilicity and chemical hardness has been calculated.


Assuntos
Antineoplásicos/farmacologia , Benzoatos/farmacologia , DNA/química , Tiadiazóis/farmacologia , Antineoplásicos/síntese química , Antineoplásicos/química , Benzoatos/química , Proliferação de Células/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Cristalografia por Raios X , Ensaios de Seleção de Medicamentos Antitumorais , Humanos , Modelos Moleculares , Teoria Quântica , Espectrometria de Fluorescência , Espectrofotometria Ultravioleta , Tiadiazóis/química , Células Tumorais Cultivadas
6.
Spectrochim Acta A Mol Biomol Spectrosc ; 190: 409-416, 2018 Feb 05.
Artigo em Inglês | MEDLINE | ID: mdl-28954253

RESUMO

The molecular level changes associated with oncogenesis precede the morphological changes in cells and tissues. Hence molecular level diagnosis would promote early diagnosis of the disease. Raman spectroscopy is capable of providing specific spectral signature of various biomolecules present in the cells and tissues under various pathological conditions. The aim of this work is to develop a non-linear multi-class statistical methodology for discrimination of normal, neoplastic and malignant cells/tissues. The tissues were classified as normal, pre-malignant and malignant by employing Principal Component Analysis followed by Artificial Neural Network (PC-ANN). The overall accuracy achieved was 99%. Further, to get an insight into the quantitative biochemical composition of the normal, neoplastic and malignant tissues, a linear combination of the major biochemicals by non-negative least squares technique was fit to the measured Raman spectra of the tissues. This technique confirms the changes in the major biomolecules such as lipids, nucleic acids, actin, glycogen and collagen associated with the different pathological conditions. To study the efficacy of this technique in comparison with histopathology, we have utilized Principal Component followed by Linear Discriminant Analysis (PC-LDA) to discriminate the well differentiated, moderately differentiated and poorly differentiated squamous cell carcinoma with an accuracy of 94.0%. And the results demonstrated that Raman spectroscopy has the potential to complement the good old technique of histopathology.


Assuntos
Colo do Útero/patologia , Espectroscopia de Luz Próxima ao Infravermelho/métodos , Análise Espectral Raman/métodos , Neoplasias do Colo do Útero/patologia , Diferenciação Celular , Análise Discriminante , Feminino , Humanos , Redes Neurais (Computação) , Análise de Componente Principal
7.
J Biomol Struct Dyn ; 35(4): 817-828, 2017 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-26999261

RESUMO

4-[3-acetyl-5-(acetylamino)-2,3-dihydro-1,3,4-thiadiazole-2-yl]phenyl benzoate from the family of thiadiazole derivative has been newly synthesized. It has good anticancer activity as well as antibacterial and less toxic in nature, its binding characteristics are therefore of huge interest for understanding pharmacokinetic mechanism of the drug. The binding of thiadiazole derivative to human serum albumin (HSA) has been investigated by studying its quenching mechanism, binding kinetics and the molecular distance, r between the donor (HSA) and acceptor (thiadiazole derivative) was estimated according to Forster's theory of non-radiative energy transfer. The Gibbs free energy (ΔG), enthalpy (ΔH) and entropy (ΔS) changes of temperature-dependent Kb was calculated, which explains that the reaction is spontaneous and exothermic. The microenvironment of HSA have also been studied using synchronous fluorescence spectroscopy, and the feature of thiadiazole derivative-induced structural changes of HSA have been carried using Fourier transform infrared spectroscopy and the Molecular modelling simulations explore the hydrophobic and hydrogen bonding interactions.


Assuntos
Biologia Computacional , Albumina Sérica/química , Albumina Sérica/metabolismo , Espectrometria de Fluorescência , Tiadiazóis/química , Tiadiazóis/metabolismo , Sítios de Ligação , Humanos , Ligações de Hidrogênio , Interações Hidrofóbicas e Hidrofílicas , Ligação Proteica , Conformação Proteica , Espectrofotometria Ultravioleta , Espectroscopia de Infravermelho com Transformada de Fourier , Termodinâmica
8.
Artigo em Inglês | MEDLINE | ID: mdl-27475997

RESUMO

Urine has emerged as one of the diagnostically potential bio fluids, as it has many metabolites. As the concentration and the physiochemical properties of the urinary metabolites may vary under pathological transformation, Raman spectroscopic characterization of urine has been exploited as a significant tool in identifying several diseased conditions, including cancers. In the present study, an attempt was made to study the high wavenumber (HWVN) Raman spectroscopic characterization of urine samples of normal subjects, oral premalignant and malignant patients. It is concluded that the urinary metabolites flavoproteins, tryptophan and phenylalanine are responsible for the observed spectral variations between the normal and abnormal groups. Principal component analysis-based linear discriminant analysis was carried out to verify the diagnostic potentiality of the present technique. The discriminant analysis performed across normal and oral premalignant subjects classifies 95.6% of the original and 94.9% of the cross-validated grouped cases correctly. In the second analysis performed across normal and oral malignant groups, the accuracy of the original and cross-validated grouped cases was 96.4% and 92.1% respectively. Similarly, the third analysis performed across three groups, normal, oral premalignant and malignant groups, classifies 93.3% and 91.2% of the original and cross-validated grouped cases correctly.


Assuntos
Metaboloma , Neoplasias Bucais/metabolismo , Neoplasias Bucais/urina , Lesões Pré-Cancerosas/metabolismo , Lesões Pré-Cancerosas/urina , Análise Espectral Raman , Adulto , Idoso , Análise Discriminante , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Padrões de Referência , Adulto Jovem
9.
J Biomol Struct Dyn ; 34(6): 1264-81, 2016 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-26368536

RESUMO

4-[(1Z)-1-(2-carbamothioylhydrazinylidene)ethyl]phenyl acetate [Ace semi],4-[(1Z)-1-(2-carbamothioylhydrazinylidene)ethyl]phenyl propanoate [Pro semi] from the family of thiosemicarbazones derivative has been newly synthesized. It has good anticancer activity as well as antibacterial and it is also less toxic in nature, its binding characteristics are therefore of huge interest for understanding pharmacokinetic mechanism of the drug. The binding of thiosemicarbazone derivative to human serum albumin (HSA) has been investigated by studying its quenching mechanism, binding kinetics and the molecular distance (r) between donor (HSA) and acceptor (thiosemicarbazone derivative) was estimated according to Forster's theory of non-radiative energy transfer using fluorescence spectroscopy. The binding dynamics has been elaborated using synchronous fluorescence spectroscopy, and the feature of thiosemicarbazone derivative induced structural changes of HSA has been studied by circular dichorism, Fourier transform infrared spectroscopy. Molecular modelling simulations explore the hydrophobic interaction and hydrogen bonding which stabilizes the interaction.


Assuntos
Modelos Moleculares , Conformação Molecular , Albumina Sérica/química , Tiossemicarbazonas/química , Sítios de Ligação , Dicroísmo Circular , Transferência Ressonante de Energia de Fluorescência , Humanos , Ligações de Hidrogênio , Ligação Proteica , Albumina Sérica/metabolismo , Espectrofotometria Ultravioleta , Espectroscopia de Infravermelho com Transformada de Fourier , Relação Estrutura-Atividade , Termodinâmica , Tiossemicarbazonas/metabolismo
10.
Artigo em Inglês | MEDLINE | ID: mdl-26189160

RESUMO

Polarized Raman spectroscopy has emerged as a promising technique giving a wealth of information about the orientation and symmetry of bond vibrations in addition to the general chemical information from the conventional Raman spectroscopy. In this regard, polarized Raman Spectroscopic technique was employed to study the changes in the orientation of biomolecules in normal and cancerous conditions. This technique was compared to the conventional Raman spectroscopic technique and was found to yield additional information about the orientation of tyrosine, collagen and DNA. The statistically analyzed depolarization ratios by Linear Discriminant Analysis yielded better accuracy than the statistical results of conventional Raman spectroscopy. Thus, this study reveals that polarized Raman spectroscopy has better diagnostic potential than the conventional Raman spectroscopic technique.


Assuntos
Colo do Útero/química , Colo do Útero/patologia , Análise Espectral Raman/métodos , Neoplasias do Colo do Útero/química , Neoplasias do Colo do Útero/patologia , Análise Discriminante , Desenho de Equipamento , Feminino , Humanos , Análise Espectral Raman/instrumentação
11.
J Biochem Mol Toxicol ; 29(8): 373-81, 2015 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-25906763

RESUMO

A newly synthesized 1, 4-bis ((4-((4-heptylpiperazin-1-yl) methyl)-1H-1, 2, 3-triazol-1-yl) methyl) benzene from the family of piperazine derivative has good anticancer activity, antibacterial and low toxic nature; its binding characteristics are therefore of huge interest for understanding pharmacokinetic mechanism of the drug. The binding of piperazine derivative to bovine serum albumin (BSA) was investigated using fluorescence spectroscopy. The molecular distance r between the donor (BSA) and acceptor (piperazine derivative) was estimated according to Forster's theory of nonradiative energy transfer. The physicochemical properties of piperazine derivative, which induced structural changes in BSA, have been studied by circular dichroism and those chemical environmental changes were probed using Raman spectroscopic analysis. Further, the binding dynamics was expounded by synchronous fluorescence spectroscopy and molecular modeling studies explored the hydrophobic interaction and hydrogen bonding results, which stabilize the interaction.


Assuntos
Piperazinas/química , Soroalbumina Bovina/química , Triazóis/química , Ligações de Hidrogênio , Interações Hidrofóbicas e Hidrofílicas , Simulação de Acoplamento Molecular , Ligação Proteica , Análise Espectral
12.
Analyst ; 140(12): 4170-81, 2015 Jun 21.
Artigo em Inglês | MEDLINE | ID: mdl-25909647

RESUMO

The objective of the study is to characterize the endogenous porphyrin fluorescence in a dimethylbenz(a)anthracene (DMBA) induced mouse skin tumor model using native fluorescence emission and excitation spectroscopy. Two intensity ratio parameters I580/I635 and I420/I515 were selected to represent the key fluorophore of endogenous porphyrins from emission and excitation spectra recorded in vivo from 31 DMBA treated animals and 5 control animals. In the emission spectrum, the endogenous porphyrin was elevated at 635 nm in different transformation lesions such as hyperplasia, papilloma, dysplasia, ESCC and WDSCC. This is corroborated by the endogenous porphyrin elevation at 420, 515, 550 and 588 nm in the WDSCC lesions from the excitation spectra. The elevation of endogenous porphyrin, probably protoporphyrin IX (PpIX), is due to biochemical and metabolic alterations in epithelial cells during tissue transformation. The loss of ferrochelatase activity might be responsible for enhanced PpIX in the transformed tissues. The sensitivity and specificity were determined for different lesion pairs from the scatter plot based on the discrimination value by validation with histopathological results. The emission intensity ratio I580/I635 at 405 nm excitation was selected to discriminate normal from hyperplasia, hyperplasia from papilloma, papilloma from dysplasia, dysplasia from early squamous cell carcinoma (ESCC), and ESCC from well differentiated squamous cell carcinoma (WDSCC) with specificities of 100%, 88%, 100%, 86%, and 100% and sensitivities of 100%, 80%, 100%, 100% and 100% respectively. Similarly, the excitation intensity ratio I420/I515 for 635 nm emission used to discriminate between WDSCC lesions and normal tissue gives 100% specificity and 100% sensitivity.


Assuntos
9,10-Dimetil-1,2-benzantraceno/toxicidade , Carcinogênese/efeitos dos fármacos , Transformação Celular Neoplásica/efeitos dos fármacos , Pele/efeitos dos fármacos , Pele/patologia , Animais , Feminino , Masculino , Camundongos , Porfirinas/metabolismo , Pele/metabolismo , Espectrometria de Fluorescência , Fatores de Tempo
13.
Biomed Pharmacother ; 69: 170-8, 2015 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-25661354

RESUMO

Chitosan functionalized luminescent rare earth doped terbium nanoparticles (LaF3:Tb(3+)/chi NPs) as a drug carrier for methotrexate (MTX) was designed using a simple chemical precipitation method. The synthesized chitosan functionalized nanoparticles were found to be spherical in shape with an average diameter of 10-12nm. They are water soluble and biocompatible, in which the hydroxyl and amino functional groups on its surface are utilized for the bioconjugation of the anticancer drug, the methotrexate. The nature of MTX binding with LaF3:Tb(3+)/chi nanoparticles were examined using X-ray diffraction, zeta potential analyzer and transmission electron microscopy. The other interactions due to complex formation between MTX and LaF3:Tb(3+)/chi NPs were carried out by UV-Visible, steady and excited state fluorescence spectroscopy. The photo-physical characterization revealed that the adsorption and release of MTX from LaF3:Tb(3+)/chi NPs is faster than gold nanoparticles and also confirms that this may be due to weak interaction i.e. the Vander Waals force of attraction between the carboxyl and amino group of drug and nanoparticles. The maximum percentage yield and entrapment efficiency of 85.91±0.71 and 83.82± 0.14 were achieved at a stochiometric ratio of 4:5 of MTX and LaF3:Tb(3+)/chi nanoparticles respectively. In addition, antitumoral activity study reveals that MTX conjugated LaF3:Tb(3+)/chi nanoparticles show higher cytotoxic effect on MCF-7 breast cancer cell lines than that of free MTX.


Assuntos
Quitosana/química , Sistemas de Liberação de Medicamentos , Lantânio/química , Metotrexato/farmacologia , Nanopartículas/química , Térbio/química , Apoptose/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Relação Dose-Resposta a Droga , Humanos , Concentração Inibidora 50 , Células MCF-7 , Metotrexato/química , Nanopartículas/ultraestrutura , Espectrometria de Fluorescência , Espectrofotometria Ultravioleta , Eletricidade Estática , Fatores de Tempo , Difração de Raios X
14.
J Fluoresc ; 25(1): 79-85, 2015 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-25618462

RESUMO

Recently, deoxyribonucleic acid (DNA) based biomarker(s) detection has been employed for cancer diagnosis. Earlier reports have suggested the presence of more DNA in the saliva of oral squamous cell carcinoma (OSCC) than normal by electrophoresis technique. Based on these, steady state and excited state kinetics of salivary DNA has been performed with 27 normal subjects and 67 OSCC patients saliva using ethidium bromide as a probe to look for the possibility in discrimination between them. On statistical analysis the sensitivity and specificity of 88.9 and 94.0 % has been achieved from the fluorescence emission spectra and 88.9 and 92.5 % with that of fluorescence excitation.


Assuntos
Carcinoma de Células Escamosas , DNA/química , Etídio/química , Neoplasias Bucais , Saliva/química , Espectrometria de Fluorescência/métodos , Adulto , DNA/análise , Feminino , Humanos , Cinética , Masculino , Pessoa de Meia-Idade
15.
J Fluoresc ; 24(4): 1199-205, 2014 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-24832355

RESUMO

Urine is one of the diagnostically potential bio fluids, as it contains many metabolites and some of them are native fluorophores. These fluorophores distribution and the physiochemical properties may vary during any metabolic change or at different pathologic conditions. Since urine is a multicomponent fluid, synchronous luminescence technique, a powerful tool has been adopted to analyse multicomponents in single spectrum and to resolve emission spectrum without much of photobleaching of fluorophores. In this study, urine samples of both normal subjects and cancer patients were characterised using synchronous luminescence spectroscopy with a Stokes shift of 20 nm. Different ratio parameters were calculated from the intensity values of the synchronous luminescence spectra and they were used as input variables for a multiple linear discriminant analysis across normal and cancer groups. The stepwise linear discriminant analysis classifies 90.3% of the original grouped cases and 88.6% of the cross-validated grouped cases correctly.


Assuntos
Neoplasias/urina , Pteridinas/urina , Riboflavina/urina , Adulto , Idoso , Feminino , Voluntários Saudáveis , Humanos , Medições Luminescentes , Masculino , Pessoa de Meia-Idade , Neoplasias/metabolismo , Neoplasias/patologia , Sensibilidade e Especificidade , Adulto Jovem
16.
J Biomed Opt ; 19(3): 37003, 2014 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-24647974

RESUMO

Steady-state and time-resolved fluorescence spectroscopy were employed in the discrimination of cervical cancer patients from healthy subjects using urine samples. Fluorescence emission at 390 and 440 nm was considered to monitor the fluorescence of indoxyl sulfate and neopterin. Significant spectral differences were observed between healthy and cancer subjects. Different ratio parameters were calculated from the spectral intensity at 280- and 350-nm excitation and were subjected to stepwise linear discriminant analysis. In total, 84.0% of samples were correctly classified at 280 nm and 96.4% were correctly classified at 350 nm. The fluorescence decay kinetics of urine samples at 390-nm emission was best described by bi- exponential fits, whereas the decay characteristics at 440 nm of urine samples was best explained by bi-exponential fits and, in some cases, by tri-exponential fits. However, the decay kinetics of both indoxyl sulfate and neopterin standards was well described by bi-exponential decays. Based on the fluorescence emission characteristics and statistical analysis, the fluorophores indoxyl sulfate, neopterin, and riboflavin may be considered as potential biomarkers for cervical cancer diagnosis.


Assuntos
Biomarcadores/urina , Espectrometria de Fluorescência/métodos , Urinálise/métodos , Neoplasias do Colo do Útero/urina , Adulto , Estudos de Casos e Controles , Análise Discriminante , Feminino , Humanos , Indicã/urina , Pessoa de Meia-Idade , Neopterina/urina , Adulto Jovem
17.
Int Sch Res Notices ; 2014: 430412, 2014.
Artigo em Inglês | MEDLINE | ID: mdl-27379265

RESUMO

Fluorescence spectroscopy was examined as a potential technique for identification and classification of bacterial pathogens. Colonies of Staphylococcus aureus, Pseudomonas aeruginosa, Salmonella typhi, and Klebsiella pneumoniae on agar plates were measured directly using a laboratory spectrofluorimeter coupled with optical fiber. Steady state fluorescence spectra were collected following excitation at 280 nm (tryptophan) and 380 nm (NADH). Results showed that fluorescence lifetime decays of tryptophan at 280 nm excitation from the four organisms were best described with triexponential fit and it reveals the existence of different protein conformation. The emission spectroscopy of the four bacteria at 380 nm excitation (NADH) provided better classification (100% of original grouped cases correctly classified and 98.1% of cross-validated grouped cases correctly classified) than that of 280 nm excitation (tryptophan). Our results demonstrated that optical fiber-based fluorescence identification and classification of bacteria is rapid, easy to perform, and of low cost compared to standard methods.

18.
Adv Healthc Mater ; 3(1): 10-29, 2014 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-23949967

RESUMO

Semiconductor nanoparticles (or quantum dots, QDs) exhibit unique optical and electronic properties such as size-controlled fluorescence, high quantum yields, and stability against photobleaching. These properties allow QDs to be used as optical labels for multiplexed imaging and in drug delivery detection systems. Luminescent silicon QDs and surface-modified silicon QDs have also been developed as potential minimally toxic fluorescent probes for bioapplications. Silicon, a well-known power electronic semiconductor material, is considered an extremely biocompatible material, in particular with respect to blood. This review article summarizes existing knowledge related to and recent research progress made in the methods for synthesizing silicon QDs, as well as their optical properties and surface-modification processes. In addition, drug delivery systems and in vitro and in vivo imaging applications that use silicon QDs are also discussed.


Assuntos
Pontos Quânticos/metabolismo , Silício/química , Animais , Materiais Biocompatíveis/química , Materiais Biocompatíveis/metabolismo , Portadores de Fármacos/química , Humanos , Neoplasias/diagnóstico , Pontos Quânticos/química , RNA Interferente Pequeno/metabolismo , Espectroscopia de Luz Próxima ao Infravermelho
19.
J Photochem Photobiol B ; 130: 153-60, 2014 Jan 05.
Artigo em Inglês | MEDLINE | ID: mdl-24333763

RESUMO

A pilot study has been carried out using human saliva in differentiating the normal subjects from that of oral squamous cell carcinoma (OSCC) patients, using the autofluorescence spectroscopy at 405nm excitation. A markable difference in the spectral signatures between the saliva of normal subjects and that of oral cancer patients has been noticed. The possible reasons for the altered spectral signature may be due to the presence of endogenous porphyrin, NAD(P)H and FAD in the exfoliated cells from saliva. The elevated level of porphyrin in saliva of OSCC patients may be attributed to the disturbances in the amino acid degradation pathway and heme biosynthetic pathway, during the transformation of normal into malignant cells. The integrated area under the curve of fluorescence emission spectrum at 405nm excitation and also fluorescence excitation spectrum for 625nm emission were compared for the saliva of normal and oral cancer patients. The area under the curve for the emission spectrum provides 85.7% sensitivity and 93.3% specificity, where as the fluorescence excitation spectrum discriminates the same with 84.1% sensitivity and 93.2% specificity.


Assuntos
Carcinoma de Células Escamosas/metabolismo , Neoplasias Bucais/metabolismo , Saliva/metabolismo , Adulto , Idoso , Idoso de 80 Anos ou mais , Biomarcadores/metabolismo , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Projetos Piloto , Espectrometria de Fluorescência
20.
J Fluoresc ; 24(2): 613-23, 2014 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-24292864

RESUMO

The present work aims to investigates the native fluorescence and time resolved fluorescence spectroscopic characterization of oral tissues under UV excitation. The fluorescence emission spectra of oral tissues at 280 nm excitation were obtained. From the spectra, it was observed that the alteration in the biochemical and morphological changes present in tissues. Subsequently, the Full width at Half Maximum (FWHM) of every individual spectra of 20 normal and 40 malignant subjects were calculated. The student's t-test analysis reveals that the data were statistically significant (p = 0.001). The fluorescence excitation spectra at 350 nm emission of malignant tissues confirms the alteration in protein fluorescence with respect to normal counterpart. To quantify the observed spectral differences, the two ratio variables R1 = I275/I310 and R2 = I310/I328 were introduced in the excitation spectra. Among them, the Linear Discriminant Analysis (LDA) of R1 reveals better classification with 86.4 % specificity and 82.5 % sensitivity. The fluorescence decay kinetics of oral tissues was obtained at 350 nm emission and it was found that the decay kinetics was triple exponential. Then the ROC analysis of fractional amplitudes and component lifetime reveals that the average lifetime shows 77 % sensitivity and 70 % specificity with the cut off value 4.85 ns. Briefly, the average lifetime exhibits better statistical significance when compared to fractional amplitudes and component lifetimes.


Assuntos
Neoplasias Bucais/patologia , Boca/química , Espectrometria de Fluorescência/métodos , Estudos de Casos e Controles , Humanos , Técnicas In Vitro
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