Kuku, G. | Sariçam, M. | Mert, S. | Çulha, Mustafa

Conference Object | 2015 | Proceedings of SPIE - The International Society for Optical Engineering9487

There is an ongoing effort to obtain molecular level information from living cells using surface-enhanced Raman scattering (SERS) not only to understand changes of cellular processes upon exposure to external stimuli but also to decide the status of cells; whether they are healthy or abnormal. In our research effort, we investigate how much information can be obtained from living cells to use for decision making about the cellular processes using SERS. The undertaken studies include cytotoxicity assessment of the nanomaterials and differentiation of the healthy and cancer cells. In the first case, A549 (lung cancer) and HDF (human d . . .ermal fibroblast) cells were incubated with 50 nm gold nanoparticles (AuNP) and exposed to three different nanoparticles (Zinc oxide nanoparticles (ZnO NPs), titanium dioxide nanoparticles (TiO2) and single walled carbon nanotubes (SWCNTs)) to perform SERS analysis and track the cellular response to these nanomaterials (NMs). After the principal component analysis on the spectral data, it was shown that the NPs exposed samples could be differentiated through SERS. In the second case, SERS spectra obtained from human kidney adenocarcinoma (ACHN), human kidney carcinoma (A-498) and non-cancerous human kidney embryonic cells (HEK 293) were used to diagnose metastatic, primary and non-cancerous cell lines. Linear discriminant analysis (LDA) based on principal component analysis (PCA) was applied to collected multidimensional SERS spectral data set to differentiate three different cell lines. © 2015 SPIE Daha fazlası Daha az

Çulha, Mustafa | Karatas, O.F. | Aydin, O. | Kahraman, M. | Keseroglu, K. | Sayin, I. | Bayrak, O.F.

Conference Object | 2009 | Progress in Biomedical Optics and Imaging - Proceedings of SPIE7192

The development of an assay for the detection of gene mutations has been attempted based on surface-enhanced Raman scattering (SERS). Using multiplexing property and high sensitivity of SERS technique, the detection of all mutation possibilities on one given spot is achievable. To test the feasibility of approach, SNPs and other types of mutations such as insertion and deletion are investigated. The PCR amplified and isolated genomic DNA without PCR amplification is immobilized on poly-L/D-lysine coated glass surface after denaturing with heating. The SERS probes are prepared by simultaneous attachment of oligonucleotides complement . . .ary to the target mutation regions and Raman active dyes to 13 nm gold nanoparticles (GNPs). After the hybridization of SERS probes on the poly-L/D-lysine surfaces, it was stained with silver colloidal nanoparticles for further enhancement of Raman scattering. In the second approach, Raman active dyes are chemically attached on gold nanoparticles and a thin layer of silverfilm is deposited on top of it to prepare coreshell nanoparticles. The complementary oligonucleotides to the target regions of the gene are chemically attached to silver surfaces of the nanoparticles. The promising results indicate that it is possible to detect certain mutation types without PCR amplification using the approach. © 2009 SPIE Daha fazlası Daha az

Çulha, Mustafa | Altunbek, M. | Keskin, S. | Saatçi, D.

Conference Object | 2011 | Progress in Biomedical Optics and Imaging - Proceedings of SPIE7911

Detection and identification of biomacromolecules is of critical importance in many fields ranging from biotechnology to medicine. Surface-enhanced Raman scattering (SERS) is an emerging technique for the label-free detection and identification of biological molecules and structures with its fingerprinting properties and high sensitivity. However, there are a number of obstacles for its applications for biological macromolecules due to their complexity. In this report, manipulation of microscopic processes in play during the drying of a sessile droplet as a tool to influence the nanoparticle-macromolecule packing, which has dramatic . . . effect on SERS performance, before the SERS acquisition is demonstrated. A process known as the coffee ring phenomenon jams all particles and molecular species to the edges of the droplet during drying. This uncontrolled process has dramatic effects on a SERS experiment, using colloidal metal nanoparticles as substrates, by sweeping everything to the edges and influencing the packing of nanoparticles in the droplet area. A plastic tip was dipped into a drying sample droplet to influence the uncontrolled piling up. A negatively-charged protein, BSA, a positively-charged protein, cytochrom c, and a 20-base long oligonucleotide, were used as model biomacromolecules in this study. While a minimum of one order of magnitude lower concentration improvement in detection limit was observed with negatively-charged biomacromolecules, no significant improvement was observed with positively-charged ones compared to a sample droplet left on the surface without any interference. With the demonstrated approach, picomolar-level biomolecular detection using SERS is possible. © 2011 SPIE Daha fazlası Daha az

Çulha, Mustafa | Kahraman, M. | Çam, D. | Sayin, I. | Keseroglu, K.

Conference Object | 2010 | Surface and Interface Analysis42 ( 06.07.2020 ) , pp.462 - 465

Surface-enhanced Raman scattering (SERS) is a powerful technique used for obtaining chemical information about the molecules and molecular structures in the vicinity of surfaces of noble metal nanostructures. The chemical information acquired through SERS can be used for not only characterization but also detection and identification. In a clinical setting, rapid and accurate identification of micro-organisms is critical. The biochemical information collected through the SERS spectra can be used for quick identification of micro-organisms. The concentrated silver colloidal nanoparticles (AgNPs) are simply mixed with micro-organisms . . .after culturing, and their SERS spectra acquired. Since the nanoparticles are in contact with the cell wall of the micro-organism, the biochemical information obtained is mostly assumed as originating from the cell wall which the AgNPs are in contact with, and is considered as the 'fingerprint' of the micro-organism, which can be used for the identification. Since a SERS spectrum can be acquired only in seconds, the obtained spectrum can be used for fast micro-organism identification. The reproducibility of the spectra obtained from micro-organisms is first tested, and then the obtained spectra are used for the goal. The identification of micro-organisms in mixtures is also attempted in model mixtures. It is demonstrated that the SERS can be used for fast and accurate identification of micro-organisms such as bacteria and yeast, even in their mixtures. Four bacteria, i.e. Shigella sonnei, Erwinia amylovara, Proteus vulgaris and DH5? (E. coli strain), and three yeast cells, i.e. Hyphopichia burtonii, Candida parapsilosis and Filobasidiella neoformans are used as model micro-organisms in the study. Copyright © 2010 John Wiley & Sons, Ltd Daha fazlası Daha az

Çulha, Mustafa | Kahraman, M. | Yazici, M.M. | Şahin, Fikrettin

Conference Object | 2007 | 2007 NSTI Nanotechnology Conference and Trade Show - NSTI Nanotech 2007, Technical Proceedings2 , pp.538 - 541

2007 NSTI Nanotechnology Conference and Trade Show - NSTI Nanotech 2007 -- 20 May 2007 through 24 May 2007 -- Santa Clara, CA -- 70065

Altunbek, M. | Kelestemur, S. | Çulha, Mustafa

Conference Object | 2015 | Progress in Biomedical Optics and Imaging - Proceedings of SPIE9792 , pp.538 - 541

Surface-enhanced Raman scattering (SERS) continues to strive to gather molecular level information from dynamic biological systems. It is our ongoing effort to utilize the technique for understanding of the biomolecular processes in living systems such as eukaryotic and prokaryotic cells. In this study, the technique is investigated to identify cell death mechanisms in 2D and 3D in vitro cell culture models, which is a very important process in tissue engineering and pharmaceutical applications. Second, in situ biofilm formation monitoring is investigated to understand how microorganisms respond to the environmental stimuli, which i . . .nferred information can be used to interfere with biofilm formation and fight against their pathogenic activity. © 2015 COPYRIGHT SPIE Daha fazlası Daha az

Çulha, Mustafa | Keskin, S.

Conference Object | 2012 | Progress in Biomedical Optics and Imaging - Proceedings of SPIE8234 , pp.538 - 541

Surface-enhanced Raman scattering (SERS) is a powerful technique to study the biological molecules and structures. SERS of proteins is always difficult due to their complex, flexible and diverse structures. This difficulty is one of the major obstacles hindering the applicability of SERS for the label-free detection and identification. In this study, we have employed several sample preparation approaches involving the packing AgNPs with protein molecules in a proper manner to allow the polarization of the electron system of proteins in coherence with the nanostructured noble metal system. The applicability of heat denaturation kinet . . .ics is perused for the detection and identification of proteins in model protein mixtures. Human serum albumin, transferrin, hemoglobin and the binary mixtures of these proteins are used as models. We have found that the SERS spectrum of each protein in the protein mixture is rather different at an increased temperature, which could be used to distinguish a protein in the protein mixture. © 2012 Copyright Society of Photo-Optical Instrumentation Engineers (SPIE) Daha fazlası Daha az

Kahraman, M. | Yazici, M.M. | Şahin, Fikrettin | Bayrak, Ö.F. | Topçu, E. | Çulha, Mustafa

Conference Object | 2007 | International Journal of Environmental Analytical Chemistry87 ( 10.11.2020 ) , pp.763 - 770

The identification and discrimination of microorganisms is important not only for clinical reasons but also for pharmaceutical clean room production and food-processing technology. Vibrational spectroscopy such as IR, Raman, and surface-enhanced Raman scattering (SERS) can provide a rapid 'fingerprint' on the chemical structure of molecules and is used to obtain a 'fingerprint' from microorganisms as well. Because of the requirement that a single bacterium cell and noble metal nanoparticles must be in close contact and the lack of a significant physical support to hold nanoparticles around the single bacterium cell, the acquisition . . .of SERS spectra for a single bacterium using colloidal nanoparticles could be a challenging task. The feasibility of SERS for identification down to a single bacterium is investigated. A Gram-negative bacterium, Escherichia coli, is chosen as a model for the investigation. Because the adsorption of silver nanoparticles onto the bacterial cell is an exclusive way for locating nanoparticles close to the bacterium cell, the absorption characteristics of silver nanoparticles with different surface charges are investigated. It is demonstrated that the citrate-reduced colloidal silver solution generates more reproducible SERS spectra. It is found that E. coli cells aggregate upon mixing with silver colloidal solution, and this may provide an additional benefit in locating the bacterial cell under a light microscope. It is also found that a laser wavelength in the UV region could be a better choice for the study due to the shallow penetration depth. It is finally shown that it is possible to obtain SERS spectra from a single cell down to a few bacterial cells, depending on the aggregation properties of bacterial cells for identification and discrimination. © 2007 Taylor & Francis Daha fazlası Daha az