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Dive into the research topics where Prasana Sahoo is active.

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Featured researches published by Prasana Sahoo.


Biosensors and Bioelectronics | 2013

Direct label free ultrasensitive impedimetric DNA biosensor using dendrimer functionalized GaN nanowires

Prasana Sahoo; Sumathi Suresh; S. Dhara; Garima Saini; S. Rangarajan; A. K. Tyagi

We demonstrate a very simple and generic protocol for ultrasensitive in-situ label-free detection of DNA hybridization using third generation poly(amidoamine)dendrimer (G3-PAMAM) functionalized GaN nanowires (NWs). PAMAM modified GaN NWs provides large density of docking site to immobilize significant number of probe (p-) DNA covalently. These p-DNA/PAMAM/GaN NWs sensor probes are employed to achieve an ultra-high detection limit down to attomolar level concentration of complementary target (t-) DNA. Comparative in-situ studies on single/triple base-pair mismatched, γ-irradiated and complementary t-DNA in the hybridization process reveal selectivity and specificity of the p-DNA/PAMAM/GAN NWs sensor probe over a wide range, 10(-8) to 10(-19)M, of analyte concentration. During the hybridization process, there is a substantial change in t-DNA concentration dependent interfacial polarization resistance during electrochemical impedance measurement, which forms the basis of the present DNA biosensor. This novel methodology for specific DNA sequence detection, as compared with the existing methods, is found to be very robust, highly sensitive, and reproducible.


Scientific Reports | 2015

Spatiotemporal distribution of different extracellular polymeric substances and filamentation mediate Xylella fastidiosa adhesion and biofilm formation

Richard Janissen; Duber M. Murillo; Bárbara Niza; Prasana Sahoo; Marcelo M. Nobrega; Carlos L. Cesar; Marcia L. A. Temperini; Hernandes F. Carvalho; Alessandra A. de Souza; M. A. Cotta

Microorganism pathogenicity strongly relies on the generation of multicellular assemblies, called biofilms. Understanding their organization can unveil vulnerabilities leading to potential treatments; spatially and temporally-resolved comprehensive experimental characterization can provide new details of biofilm formation, and possibly new targets for disease control. Here, biofilm formation of economically important phytopathogen Xylella fastidiosa was analyzed at single-cell resolution using nanometer-resolution spectro-microscopy techniques, addressing the role of different types of extracellular polymeric substances (EPS) at each stage of the entire bacterial life cycle. Single cell adhesion is caused by unspecific electrostatic interactions through proteins at the cell polar region, where EPS accumulation is required for more firmly-attached, irreversibly adhered cells. Subsequently, bacteria form clusters, which are embedded in secreted loosely-bound EPS, and bridged by up to ten-fold elongated cells that form the biofilm framework. During biofilm maturation, soluble EPS forms a filamentous matrix that facilitates cell adhesion and provides mechanical support, while the biofilm keeps anchored by few cells. This floating architecture maximizes nutrient distribution while allowing detachment upon larger shear stresses; it thus complies with biological requirements of the bacteria life cycle. Using new approaches, our findings provide insights regarding different aspects of the adhesion process of X. fastidiosa and biofilm formation.


Nano Letters | 2016

Nanowire Arrays as Cell Force Sensors To Investigate Adhesin-Enhanced Holdfast of Single Cell Bacteria and Biofilm Stability

Prasana Sahoo; Richard Janissen; Moniellen P. Monteiro; Alessandro Cavalli; Duber M. Murillo; Marcus V. Merfa; Carlos L. Cesar; Hernandes F. Carvalho; Alessandra A. de Souza; Erik P. A. M. Bakkers; M. A. Cotta

Surface attachment of a planktonic bacteria, mediated by adhesins and extracellular polymeric substances (EPS), is a crucial step for biofilm formation. Some pathogens can modulate cell adhesiveness, impacting host colonization and virulence. A framework able to quantify cell-surface interaction forces and their dependence on chemical surface composition may unveil adhesiveness control mechanisms as new targets for intervention and disease control. Here we employed InP nanowire arrays to dissect factors involved in the early stage biofilm formation of the phytopathogen Xylella fastidiosa. Ex vivo experiments demonstrate single-cell adhesion forces up to 45 nN, depending on the cell orientation with respect to the surface. Larger adhesion forces occur at the cell poles; secreted EPS layers and filaments provide additional mechanical support. Significant adhesion force enhancements were observed for single cells anchoring a biofilm and particularly on XadA1 adhesin-coated surfaces, evidencing molecular mechanisms developed by bacterial pathogens to create a stronger holdfast to specific host tissues.


Carbohydrate Polymers | 2016

Nanofilms of hyaluronan/chitosan assembled layer-by-layer: An antibacterial surface for Xylella fastidiosa

Jacobo Hernandez-Montelongo; Vicente Nascimento; Duber M. Murillo; Thiago B. Taketa; Prasana Sahoo; Alessandra A. de Souza; Marisa M. Beppu; M. A. Cotta

In this work, nanofilms of hyaluronan/chitosan (HA/CHI) assembled layer by layer were synthesized; their application as a potential antimicrobial material was demonstrated for the phytopathogen Xylella fastidiosa, a gram-negative bacterium, here used as a model. For the synthesis, the influence of pH and ionic strength of these natural polymer stem-solutions on final characteristics of the HA/CHI nanofilms was studied in detail. The antibacterial effect was evaluated using widefield fluorescence microscopy. These results were correlated with the chemical properties of the nanofilms, studied by FTIR and Raman spectroscopy, as well as with their morphology and surface properties characterized using SEM and AFM. The present findings can be extended to design and optimize HA/CHI nanofilms with enhanced antimicrobial behavior for other type of phytopathogenic gram-negative bacteria species, such as Xanthomonas citri, Xanthomas campestri and Ralstonia solanacearum.


Journal of Materials Chemistry C | 2013

Evolution of GaN nanowire morphology during catalyst-induced growth process

Prasana Sahoo; S. Dhara; S. Amirthapandian; M. Kamruddin

We report a very generic methodology to control the crystallographic orientation of GaN nanowires (NWs) in a chemical vapor deposition technique employing a standard vapor–liquid–solid mechanism. Incubation time was considered as a critical parameter to control the nanowire morphology. It was found that nanowires of a particular geometry, such as hexagonal, triangular, wurtzite/zinc-blende biphase, and square shaped forms could be obtained by varying the length of incubation time. The change in the diameter of the nanowires with respect to the size of the catalyst droplet was corroborated by a simple steady state model. Luminescence spectra recorded from the GaN NWs revealed the presence of a dominating wurtzite phase in all the as-grown samples. However, temperature independent behavior of two luminescence peaks, recorded especially from the biphase homostructure, was believed to originate from the radiative recombination of carriers localized at potential fluctuations in the zinc-blende and wurtzite phases discretely.


Nano Letters | 2017

InP Nanowire Biosensor with Tailored Biofunctionalization: Ultrasensitive and Highly Selective Disease Biomarker Detection

Richard Janissen; Prasana Sahoo; Clelton A. Santos; Aldeliane M. da Silva; Antonio A.G. von Zuben; Dênio Emanuel Pires Souto; Alexandre D.T. Costa; Paola Celedon; Nilson Ivo Tonin Zanchin; D. B. Almeida; Douglas Soares de Oliveira; Lauro T. Kubota; Carlos L. Cesar; Anete Pereira de Souza; M. A. Cotta

Electrically active field-effect transistors (FET) based biosensors are of paramount importance in life science applications, as they offer direct, fast, and highly sensitive label-free detection capabilities of several biomolecules of specific interest. In this work, we report a detailed investigation on surface functionalization and covalent immobilization of biomarkers using biocompatible ethanolamine and poly(ethylene glycol) derivate coatings, as compared to the conventional approaches using silica monoliths, in order to substantially increase both the sensitivity and molecular selectivity of nanowire-based FET biosensor platforms. Quantitative fluorescence, atomic and Kelvin probe force microscopy allowed detailed investigation of the homogeneity and density of immobilized biomarkers on different biofunctionalized surfaces. Significantly enhanced binding specificity, biomarker density, and target biomolecule capture efficiency were thus achieved for DNA as well as for proteins from pathogens. This optimized functionalization methodology was applied to InP nanowires that due to their low surface recombination rates were used as new active transducers for biosensors. The developed devices provide ultrahigh label-free detection sensitivities ∼1 fM for specific DNA sequences, measured via the net change in device electrical resistance. Similar levels of ultrasensitive detection of ∼6 fM were achieved for a Chagas Disease protein marker (IBMP8-1). The developed InP nanowire biosensor provides thus a qualified tool for detection of the chronic infection stage of this disease, leading to improved diagnosis and control of spread. These methodological developments are expected to substantially enhance the chemical robustness, diagnostic reliability, detection sensitivity, and biomarker selectivity for current and future biosensing devices.


Colloids and Surfaces B: Biointerfaces | 2017

Stiffness signatures along early stages of Xylella fastidiosa biofilm formation

Moniellen P. Monteiro; João H. Clerici; Prasana Sahoo; Carlos L. Cesar; Alessandra A. de Souza; M. A. Cotta

The pathogenicity of Xylella fastidiosa is associated with its systematic colonization of the plant xylem, forming bacterial biofilms. Mechanisms of bacterial transport among different xylem vessels, however, are not completely understood yet, but are strongly influenced by the presence of extracellular polymeric substances (EPS), which surrounds the assembly of cells forming the biofilm. In this work, we show quantitative measurements on the elastic properties of the system composed by EPS and bacterial cell. In order to investigate the mechanical properties of this system, force spectroscopy and confocal Raman measurements were carried out during Xylella fastidiosa subsp. pauca initial stages of adhesion and cluster formation. We show that stiffness progressively decreases with increasing culture growth time, from two to five days. For early adhesion samples, stiffness values are quite different at the bacterial polar and body regions. Lower stiffness values at the cell pole suggest a flexible mechanical response at this region, associated with first cell adhesion to a surface. These results correlate very well with our observations of cell motion within microchannels, under conditions simulating xylem flow. Both the oscillatory movement of vertically attached single cells, as well as the transport of cell clusters within the biofilm matrix can be explained by the presence of softer materials at the cell pole and EPS matrix. Our results may thus add to a more detailed understanding of mechanisms used by cells to migrate among vessels in plant xylem.


Proceedings of SPIE | 2016

A force sensor using nanowire arrays to understand biofilm formation(Conference Presentation)

Prasana Sahoo; Alessandro Cavalli; Vitor B. Pelegati; Duber M. Murillo; Alessandra A. de Souza; Carlos L. Cesar; Erik P. A. M. Bakkers; M. A. Cotta

Understanding the cellular signaling and function at the nano-bio interface can pave the way towards developing next-generation smart diagnostic tools. From this perspective, limited reports detail so far the cellular and subcellular forces exerted by bacterial cells during the interaction with abiotic materials. Nanowire arrays with high aspect ratio have been used to detect such small forces. In this regard, live force measurements were performed ex-vivo during the interaction of Xylella fastidiosa bacterial cells with InP nanowire arrays. The influence of nanowire array topography and surface chemistry on the response and motion of bacterial cells was studied in detail. The nanowire arrays were also functionalized with different cell adhesive promoters, such as amines and XadA1, an afimbrial protein of X.fastidiosa. By employing the well-defined InP nanowire arrays platform, and single cell confocal imaging system, we were able to trace the bacterial growth pattern, and show that their initial attachment locations are strongly influenced by the surface chemistry and nanoscale surface topography. In addition, we measure the cellular forces down to few nanonewton range using these nanowire arrays. In case of nanowire functionalized with XadA1, the force exerted by vertically and horizontally attached single bacteria on the nanowire is in average 14% and 26% higher than for the pristine array, respectively. These results provide an excellent basis for live-cell force measurements as well as unravel the range of forces involved during the early stages of bacterial adhesion and biofilm formation.


Proceedings of SPIE | 2016

Filamentation and spatiotemporal distribution of extracellular polymeric substances: role on X.fastidiosa single cell adhesion and biofilm formation(Conference Presentation)

Richard Janissen; Duber M. Murillo; Bárbara Niza; Prasana Sahoo; Moniellen P. Monteiro; Carlos L. Cesar; Hernandes F. Carvalho; Alessandra A. de Souza; M. A. Cotta

Biofilms can be defined as a community of microorganisms attached to a surface, living embedded in a self- produced matrix of hydrated extracellular polymeric substances (EPS) which comprises most of the biofilm mass. We have recently used an extensive pool of microscopy techniques (confocal fluorescence, electron and scanning probe microscopies) at the micro and nanoscales in order to create a detailed temporal observation of Xylella fastidiosa biofilm formation, using both wild type strain and Green Fluorescent Protein (GFP)-modified cells of this citrus phytopathogen. We have identified three different EPS compositions, as well as their spatial and temporal distribution from single cell to mature biofilm formation stages. In the initial adhesion stage, soluble-EPS (S-EPS) accumulates at cell polar regions and forms a surface layer which facilitates irreversible cell attachment and cell cluster formation. These small clusters are subsequently connected by filamentous cells; further S-EPS surface coverage facilitates cell attachment and form filaments, leading to a floating framework of mature biofilms. The important role of EPS in X.fastidiosa biology was further investigated by imunolabelling experiments to detect the distribution of XadA1 adhesin, which is expressed in early stages of biofilm formation and released in outer membrane vesicles. This protein is located mainly in S-EPS covered areas, as well as on the filaments, indicating a molecular pathway to the enhanced cell attachment previously observed. These results suggest that S-EPS may thus represent an important target for disease control, slow plant colonization by the bacteria, keeping the plant more productive in the field.


SOLID STATE PHYSICS: Proceedings of the 56th DAE Solid State Physics Symposium 2011 | 2012

Self-catalyzed anisotropic growth of GaN spirals

Avinash Patsha; Prasana Sahoo; S. Dhara; A. K. Tyagi

GaN spirals with homogeneous size are grown using chemical-vapor-deposition technique in a self catalytic process. Raman and photoluminescence (PL) studies reveal wurtzite GaN phase. Nucleation of GaN sphere takes place with the agglomeration Ga clusters and simultaneous reaction with NH3. A growth mechanism involving diffusion limited aggregation process initiating supersaturation and subsequent neck formation along with possible role of thermodynamic fluctuation in different crystalline facets of GaN, is described for the anisotropic spiral structures. Temperature dependent PL spectra show strong excitonic emissions along with the presence of free-to-bound transition.

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M. A. Cotta

State University of Campinas

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S. Dhara

Indira Gandhi Centre for Atomic Research

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Carlos L. Cesar

State University of Campinas

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Alessandra A. de Souza

American Physical Therapy Association

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A. K. Tyagi

Indira Gandhi Centre for Atomic Research

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Duber M. Murillo

State University of Campinas

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Richard Janissen

State University of Campinas

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S. Dash

Indira Gandhi Centre for Atomic Research

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