Csilla Gergely - Profile on Academia.edu (original) (raw)

Papers by Csilla Gergely

Scientific Reports, 2020

In recent years, fluorescent nanodiamond (fND) particles containing nitrogen-vacancy (NV) centers... more In recent years, fluorescent nanodiamond (fND) particles containing nitrogen-vacancy (NV) centers gained recognition as an attractive probe for nanoscale cellular imaging and quantum sensing. For these applications, precise localization of fNDs inside of a living cell is essential. Here we propose such a method by simultaneous detection of the signal from the NV centers and the spectroscopic Raman signal from the cells to visualize the nucleus of living cells. However, we show that the commonly used Raman cell signal from the fingerprint region is not suitable for organelle imaging in this case. Therefore, we develop a method for nucleus visualization exploiting the region-specific shape of C-H stretching mode and further use k-means cluster analysis to chemically distinguish the vicinity of fNDs. Our technique enables, within a single scan, to detect fNDs, distinguish by chemical localization whether they have been internalized into cell and simultaneously visualize cell nucleus wi...

Neurochemistry International, 2021

HAL is a multidisciplinary open access archive for the deposit and dissemination of scientific re... more HAL is a multidisciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés. Distributed under a Creative Commons Attribution-NonCommercial| 4.0 International License

ACS Applied Materials & Interfaces, 2019

HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific r... more HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

International Journal of Experimental Dental Science, 2016

Proper treatment of dental caries demands detection of carious lesions at an early stage and a mi... more Proper treatment of dental caries demands detection of carious lesions at an early stage and a minimal invasive cavity preparation to preserve the maximum tooth structure. Various devices use fluorescence for caries detection via recording the red fluorescence generated by dentin caries under illumination. The aim of this study was to evaluate the porphyrin and pentosidine involvement in the red fluorescence observed in enamel and dentin caries when illuminated with the Soprolife® camera (Sopro, Acteon Group, La Ciotat, France) and Vistacam® camera (Dürr Dental AG, Bietigheim-Bissingen, Germany). Three techniques were used: single photon fluorescence spectroscopy, micro-Raman spectroscopy, and color analysis with ImajeJ software. Cross-sections of human teeth, scored from 0–6 with the International Caries Detection and Assessment System (ICDAS), were examined by fluorescence microscopy. Teeth spectra of each ICDAS score were compared with those of protoporphyrin IX (PpIX), porphyrin...

Stem Cell Research & Therapy, 2018

Background: Understanding stem cell behavior as a delivery tool in cancer therapy is essential fo... more Background: Understanding stem cell behavior as a delivery tool in cancer therapy is essential for evaluating their future clinical potential. Previous in-vivo studies proved the use of mesenchymal stem cells (MSCs) for local delivery of the commonest anticancer drug, paclitaxel (PTX). Dental pulp is a relatively abundant noninvasive source of MSCs. We assess dental pulp stem cells (DPSCs), for the first time, as anticancer drug carriers. Confocal Raman microscopy is a unique tool to trace drug and cell viability without labeling. Methods: Drug uptake and cell apoptosis are identified through confocal Raman microscope. We traced translocation of cytochrome c enzyme from the mitochondria, as a biomarker for apoptosis, after testing both cancer and stem cells. The viability of stem cells was checked by means of confocal Raman microscope and by cytotoxicity assays. Results: In this study, we prove that DPSCs can be loaded in vitro with the anticancerous drug without affecting their viability, which is later released in the culture medium of breast cancer cells (MCF-7 cells) in a time-dependent fashion. The induced cytotoxic damage in MCF-7 cells was observed consequently after PTX release by DPSCs. Additionally, quantitative Raman images of intracellular drug uptake in DPSCs and MCF-7 cells were obtained. Cytotoxic assays prove the DPSCs to be more resistant to PTX as compared to bone marrow-derived MSCs, provided similar conditions. Conclusions: Applications of dental stem cells for targeted treatment of cancer could be a revolution to reduce morbidity due to chemotherapy, and to increase the efficacy of systemic cancer treatment.

Langmuir : the ACS journal of surfaces and colloids, Jul 19, 2016

Selective deposition of peptides from liquid solutions to n- and p-doped silicon has been demonst... more Selective deposition of peptides from liquid solutions to n- and p-doped silicon has been demonstrated. The selectivity is governed by peptide/silicon adhesion differences. A noninvasive, fast characterization of the obtained peptide layers is required to promote their application for interfacing silicon-based devices with biological material. In this study we show that spectroscopic ellipsometry-a method increasingly used for the investigation of biointerfaces-can provide essential information about the amount of adsorbed peptide material and the degree of coverage on silicon surfaces. We observed the formation of peptide multilayers for a strongly binding adhesion peptide on p-doped silicon. Application of the patterned layer ellipsometric evaluation method combined with Sellmeier dispersion led to physically consistent results, which describe well the optical properties of peptide layers in the visible spectral range. This evaluation allowed the estimation of surface coverage, wh...

Journal of Biomedical Optics, 2015

Regenerative medicine brings promising applications for mesenchymal stem cells, such as dental pu... more Regenerative medicine brings promising applications for mesenchymal stem cells, such as dental pulp stem cells (DPSCs). Confocal Raman microscopy, a noninvasive technique, is used to study osteogenic differentiation of DPSCs. Integrated Raman intensities in the 2800 to 3000 cm -1 region (C-H stretching) and the 960 cm -1 peak (ν 1 PO 3- 4 ) were collected (to image cells and phosphate, respectively), and the ratio of two peaks 1660 over 1690 cm -1 (amide I bands) to measure the collagen cross-linking has been calculated. Raman spectra of DPSCs after 21 days differentiation reveal several phosphate peaks: ν 1 (first stretching mode) at 960 cm -1 , ν 2 at 430 cm -1 , and ν 4 at 585 cm -1 and collagen cross-linking can also be calculated. Confocal Raman microscopy enables monitoring osteogenic differentiation in vitro and can be a credible tool for clinical stem cell based research.

Nanoscale research letters, 2014

The way cells explore their surrounding extracellular matrix (ECM) during development and migrati... more The way cells explore their surrounding extracellular matrix (ECM) during development and migration is mediated by lamellipodia at their leading edge, acting as an actual motor pulling the cell forward. Lamellipodia are the primary area within the cell of actin microfilaments (filopodia) formation. In this work, we report on the use of porous silicon (pSi) scaffolds to mimic the ECM of mesenchymal stem cells from the dental pulp (DPSC) and breast cancer (MCF-7) cells. Our atomic force microscopy (AFM), fluorescence microscopy, and scanning electron microscopy (SEM) results show that pSi promoted the appearance of lateral filopodia protruding from the DPSC cell body and not only in the lamellipodia area. The formation of elongated lateral actin filaments suggests that pores provided the necessary anchorage points for protrusion growth. Although MCF-7 cells displayed a lower presence of organized actin network on both pSi and nonporous silicon, pSi stimulated the formation of extended...

Nanoscale Research Letters, 2012

Porous silicon microcavity (PSiMc) structures were used to immobilize the photosynthetic reaction... more Porous silicon microcavity (PSiMc) structures were used to immobilize the photosynthetic reaction center (RC) purified from the purple bacterium Rhodobacter sphaeroides R-26. Two different binding methods were compared by specular reflectance measurements. Structural characterization of PSiMc was performed by scanning electron microscopy and atomic force microscopy. The activity of the immobilized RC was checked by measuring the visible absorption spectra of the externally added electron donor, mammalian cytochrome c. PSi/RC complex was found to oxidize the cytochrome c after every saturating Xe flash, indicating the accessibility of specific surface binding sites on the immobilized RC, for the external electron donor. This new type of bio-nanomaterial is considered as an excellent model for new generation applications of silicon-based electronics and biological redox systems.

PloS one, 2013

A prior peripheral nerve injury in vivo, promotes a rapid elongated mode of sensory neurons neuri... more A prior peripheral nerve injury in vivo, promotes a rapid elongated mode of sensory neurons neurite regrowth in vitro. This in vitro model of conditioned axotomy allows analysis of the cellular and molecular mechanisms leading to an improved neurite re-growth. Our differential interference contrast microscopy and immunocytochemistry results show that conditioned axotomy, induced by sciatic nerve injury, did not increase somatic size of adult lumbar sensory neurons from mice dorsal root ganglia sensory neurons but promoted the appearance of larger neurites and growth cones. Using atomic force microscopy on live neurons, we investigated whether membrane mechanical properties of growth cones of axotomized neurons were modified following sciatic nerve injury. Our data revealed that neurons having a regenerative growth were characterized by softer growth cones, compared to control neurons. The increase of the growth cone membrane elasticity suggests a modification in the ratio and the in...

Journal of chemical information and modeling, Jan 28, 2014

Despite extensive recent research efforts on material-specific peptides, the fundamental problem ... more Despite extensive recent research efforts on material-specific peptides, the fundamental problem to be explored yet is the molecular interactions between peptides and inorganic surfaces. Here we used computer simulations (density functional theory and classical molecular dynamics) to investigate the adsorption mechanism of silicon-binding peptides and the role of individual amino acids in the affinity of peptides for an n-type silicon (n(+)-Si) semiconductor. Three silicon binding 12-mer peptides previously elaborated using phage display technology have been studied. The peptides' conformations close to the surface have been determined and the best-binding amino acids have been identified. Adsorption energy calculations explain the experimentally observed different degrees of affinity of the peptides for n(+)-Si. Our residual scanning analysis demonstrates that the binding affinity relies on both the identity of the amino acid and its location in the peptide sequence.

We report on a strong and tunable magnetic optical nonlinear response of Bacteriorhodopsin (BR) u... more We report on a strong and tunable magnetic optical nonlinear response of Bacteriorhodopsin (BR) under "off resonance" femtosecond (fs) pulse excitation, by detecting the polarization map of the noncollinear second harmonic signal of an oriented BR film, as a function of the input beam power. BR is a light-driven proton pump with a unique photochemistry initiated by the all trans retinal chromophore embedded in the protein. An elegant application of this photonic molecular machine has been recently found in the new area of optogenetics, where genetic expression of BR in brain cells conferred a light responsivity to the cells enabling thus specific stimulation of neurons. The observed strong tunable magnetic nonlinear response of BR might trigger promising applications in the emerging area of pairing optogenetics and functional magnetic resonance imaging susceptible to provide an unprecedented complete functional mapping of neural circuits.

Journal of the Optical Society of America B, 2013

A measurable magnetic (nonlocal) contribution to the second harmonic generation (SHG) of nonmagne... more A measurable magnetic (nonlocal) contribution to the second harmonic generation (SHG) of nonmagnetic materials is an intriguing issue related to chiral materials, such as biomolecules. Here we report the detection of an intensity-dependent optically induced magnetization of a chiral bacteriorhodopsin film under femtosecond pulse excitation (830 nm) and far from the material's resonance. The analysis of the pump intensity-dependent noncollinear SHG signal, by means of the polarization map of normalized Stokes parameters, allows one to improve the detection of the nonlinear optical magnetization M2ω contribution to the SHG signal.

Macromolecules, 2005

Recently we have presented new polyelectrolyte nanoring structures formed by self-assembly of pol... more Recently we have presented new polyelectrolyte nanoring structures formed by self-assembly of poly(ethylenimine) and poly(sodium 4-styrenesulfonate) during sequential adsorption observed by AFM microscope in liquid cell technique. In this work, filter pore size and carbonate ion concentration are identified as critical parameters for their formation. We show how these two parameters modulate the nanorings formation as a consequence of the hydrophobic polyelectrolyte domains formed into the polyelectrolyte solutions and the screening effect produced by the divalent carbonate ions present also in solutions. Also, we prove how the nanorings size is controlled through competition between electrostatic and hydrophobic interactions where the charge density of the substrate plays an important role.

The Journal of Chemical Physics, 2001

We present a comparative study of the structural parameters characterizing thin macromolecular ad... more We present a comparative study of the structural parameters characterizing thin macromolecular adsorbed films that are obtained from two optical techniques: optical waveguide lightmode spectroscopy (OWLS) and scanning angle reflectometry (SAR). We use polyelectrolyte multilayers and polyelectrolyte multilayers/protein films to perform this study. The comparison between the information obtained with the two methods is possible because the buildup of the polyelectrolyte multilayers is known to become substrate independent after the deposition of the first few polyelectrolyte layers. The analysis of the optical data requires usually to postulate a refractive index profile for the interface. Two profiles have been used: the homogeneous and isotropic monolayer and the bilayer profiles. When the refractive index profile of an adsorbed film is well approximated by a homogeneous and isotropic monolayer, as shown by using an analysis of the deposited films in terms of optical invariants, the...

Journal of Chemical Information and Modeling, 2013

Journal of Biomedical Optics, 2013

Confocal Raman microscopy is a noninvasive, label-free imaging technique used to study apoptosis ... more Confocal Raman microscopy is a noninvasive, label-free imaging technique used to study apoptosis of live MCF-7 cells. The images are based on Raman spectra of cells components, and their apoptosis is monitored through diffusion of cytochrome c in cytoplasm. K-mean clustering is used to identify mitochondria in cells, and correlation analysis provides the cytochrome c distribution inside the cells. Our results demonstrate that incubation of cells for 3 h with 10 μM of paclitaxel does not induce apoptosis in MCF-7 cells. On the contrary, incubation for 30 min at a higher concentration (100 μM) of paclitaxel induces gradual release of the cytochrome c into the cytoplasm, indicating cell apoptosis via a caspase independent pathway.

Biophysical Journal, 1997

The changes in the photocycle of the wild type and several mutant bacteriorhodopsin (D96N, E204Q,... more The changes in the photocycle of the wild type and several mutant bacteriorhodopsin (D96N, E204Q, and D212N) were studied on dried samples, at relative humidities of 100% and 50%. Samples were prepared from suspensions at pH -5 and at pH -9. Intermediate M with unprotonated Schiff base was observed at the lower humidity, even in the case where the photocycle in suspension did not contain this intermediate (mutant D212N, high pH). The photocycle of the dried sample stopped at intermediate M1 in the extracellular conformation; conformation change, switching the accessibility of the Schiff base to the cytoplasmic side, and proton transport did not occur. The photocycle decayed slowly by dissipating the absorbed energy of the photon, and the protein returned to its initial bacteriorhodopsin state, through several M1-like substates. These substates presumably reflect different paths of the proton back to the Schiff base, as a consequence of the bacteriorhodopsin adopting different conformations by stiffening on dehydration. All intermediates requiring conformational change were hindered in the dried form. The concentration of intermediate L, which appears after isomerization of the retinal from all-trans to 13-cis, during local relaxation of the protein, was unusually low in dried samples. The lack of intermediates N and 0 demonstrated that the M state did not undergo a change from the extracellular to the cytoplasmic conformation (M1 to M2 transition), as already indicated by Fourier transform infrared spectroscopy, quasielastic incoherent neutron scattering, and electric signal measurements described in the literature. 1993; Zimainyi et al., 1993; Chizhov et al., 1996), which implies that the actual transport process is much more complex. The major functional steps are as follows: photoisomerization of the retinal from the all-trans to the 13-cis conformation; transfer of the proton to the internal proton