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Bulunan: 112 Adet 0.001 sn
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Surface-enhanced Raman scattering on aggregates of silver nanoparticles with definite size

Çulha, Mustafa | Kahraman, M. | Tokman, N. | Türkoglu, G.

Article | 2008 | Journal of Physical Chemistry C112 ( 28 ) , pp.10338 - 10343

Aggregation behavior of colloidal silver nanoparticles for surface-enhanced Raman scattering (SERS) on a hydrophobic surface is investigated. A regular glass slide is used to deposit dicholoromethylsilane in order to inactivate the free hydroxyl groups and increase the hydrophobicity of the glass surface. A submicron volume of colloidal suspension is spotted on the hydrophobic surface. During the evaporation of water from the droplet, the nanoparticles start to form aggregates with a definite size and shape. Increasing colloidal suspension concentration by more than 4 times helped to complete the size of silver nanoparticles aggrega . . .tes to about 1 µm diameter. The SERS activity of aggregates was investigated using Rhodamine 6G as a probe. The aggregates formed from higher colloidal suspension concentrations show a significant improvement in SERS activity. The SERS enhancement on the aggregates formed on hydrophobic surfaces is at least 1 order of magnitude greater than the disordered aggregates prepared on the regular glass surface using the same colloidal suspension. The SERS enhancement factor for the aggregates and the limit of detection (LOD) for Rhodamine 6G are estimated as about 3 × 105 and 1.0 × 10-5, respectively. The percent coefficient of variance (CV) improved about 300% by increasing the colloidal suspension concentration 8-fold on the prepared aggregates. A minimum 2-fold increase in SERS enhancement on the aggregates prepared from silver colloidal suspension containing NaCl and SDS is also observed. © 2008 American Chemical Society Daha fazlası Daha az

Silencing Breast Cancer Genes Using Morpholino Embedded DNA-Tile-AuNPs Nanostructures

Tunç, C.U. | Öztaş, D.Y. | Uzunoglu, D. | Bayrak, Ö.F. | Çulha, Mustafa

Article | 2019 | Human Gene Therapy30 ( 12 ) , pp.1547 - 1558

There is an ongoing effort to increase the efficiency of gene delivery for the regulation of diseases-related genes. In this report, we demonstrate the efficiency of a DNA-based nanostructure to deliver morpholino antisense oligonucleotides for the upregulated genes in breast cancer as an alternative to the currently used delivery systems. A DNA-tile structure is constructed by embedding antisense oligonucleotides targeting the HER2 and ER? genes. Then, the sticky ends of the DNA-tile nanostructures are hybridized to gold nanoparticles (AuNPs) coated with the complementary oligonucleotides to enhance their cellular uptake. It is fou . . .nd that the morpholino antisense oligonucleotide embedded DNA-tile-AuNPs structure is 30% more effective than the liposome-based system to deliver morpholinos and induce gene silencing in breast cancer cells. The results of the study suggest that the prepared novel nanostructure is an effective and biocompatible carrier that can be used in in vitro gene silencing studies and can be further pursued in in vivo studies. © Copyright 2019, Mary Ann Liebert, Inc., publishers 2019 Daha fazlası Daha az

Tracing Size and Surface Chemistry-Dependent Endosomal Uptake of Gold Nanoparticles Using Surface-Enhanced Raman Scattering

Öztaş, D.Y. | Altunbek, M. | Uzunoglu, D. | Yllmaz, H. | Cetin, D. | Suludere, Z. | Çulha, Mustafa

Article | 2019 | Langmuir35 ( 11 ) , pp.4020 - 4028

Surface-enhanced Raman scattering (SERS)-based single-cell analysis is an emerging approach to obtain molecular level information from molecular dynamics in a living cell. In this study, endosomal biochemical dynamics was investigated based on size and surface chemistry-dependent uptake of gold nanoparticles (AuNPs) on single cells over time using SERS. MDA-MB-231 breast cancer cells were exposed to 13 and 50 nm AuNPs and their polyadenine oligonucleotide-modified forms by controlling the order and combination of AuNPs. The average spectra obtained from 20 single cells were analyzed to study the nature of the biochemical species or . . .processes taking place on the AuNP surfaces. The spectral changes, especially from proteins and lipids of endosomal vesicles, were observed depending on the size, surface chemistry, and combination as well as the duration of the AuNP treatment. The results demonstrate that SERS spectra are sensitive to trace biochemical changes not only the size, surface chemistry, and aggregation status of AuNPs but also the endosomal maturation steps over time, which can be simple and fast way for understanding the AuNP behavior in single cell and useful for the assisting and controlling of AuNP-based gene or drug delivery applications. © 2019 American Chemical Society Daha fazlası Daha az

Thermally exfoliated graphene oxide reinforced fluorinated pentablock poly(l -lactide-co-?-caprolactone) electrospun scaffolds: Insight into antimicrobial activity and biodegradation

Okan, B.S. | Marset, A. | Seyyed Monfared Zanjani, J. | Sut, P.A. | Sen, O. | Çulha, Mustafa | Menceloglu, Y.

Article | 2016 | Journal of Applied Polymer Science133 ( 22 ) , pp.4020 - 4028

Three-dimensional fluorinated pentablock poly(l-lactide-co-?-caprolactone)-based scaffolds were successfully produced by the incorporation of thermally exfoliated graphene oxide (TEGO) as an antimicrobial agent with an electrospinning technique. In a ring-opening polymerization, the fluorinated groups in the middle of polymer backbone were attached with a perfluorinated reactive stabilizer having oxygen-carrying ability. The fiber diameter and its morphologies were optimized through changes in TEGO amount, voltage, polymer concentration, and solvent type to obtain an ideal scaffold structure. Instead of the widely used graphene oxid . . .e synthesized by Hummer's method, TEGO sheets having a low amount of oxygen produced by thermal expansion were integrated into the fiber structure to investigate the effect of the oxygen functional groups of TEGO sheets on the degradation and antimicrobial activity of the scaffolds. There was no antimicrobial activity in TEGO-reinforced scaffolds in the in vitro tests in contrast to the literature. This study confirmed that a low number of oxygen functional groups on the surface of TEGO restricted the antimicrobial activity of the fabricated composite scaffolds. © 2016 Wiley Periodicals, Inc Daha fazlası Daha az

Boron nitride nanotubes included thermally cross-linked gelatin-glucose scaffolds show improved properties

Şen, Ö. | Çulha, Mustafa

Article | 2016 | Colloids and Surfaces B: Biointerfaces138 , pp.41 - 49

Boron nitride nanotubes (BNNTs) are increasingly investigated for their medical and biomedical applications due to their unique properties such as resistance to oxidation, thermal and electrical insulation, and biocompatibility. BNNTs can be used to enhance mechanical strength of biomedical structures such as scaffolds in tissue engineering applications. In this study, we report the use of BNNTs and hydroxylated BNNTs (BNNT-OH) to improve the properties of gelatin-glucose scaffolds prepared with electrospinning technique. Human dermal fibroblast (HDF) cells are used for the toxicity assessment and cell seeding studies. It is found t . . .hat the addition of BNNTs into the scaffold does not influence cell viability, decreases the scaffold degradation rate, and improves cell attachment and proliferation compared to only-gelatin scaffold. © 2015 Elsevier B.V Daha fazlası Daha az

Surface-raman scattering for medical applications

Çulha, Mustafa

Book Part | 2012 | Biomedical Nanosensors , pp.97 - 119

[No abstract available]

Pluronic block copolymer-mediated interactions of organic compounds with noble metal nanoparticles for SERS analysis

Abdullin, T.I. | Bondar, O.V. | Shtyrlin, Y.G. | Kahraman, M. | Çulha, Mustafa

Article | 2010 | Langmuir26 ( 7 ) , pp.5153 - 5159

The composite silver and gold nanoparticles (AgNPs and AuNPs) coated with nonionic amphiphilic block copolymers (Pluronics L121, F68, or F127) are prepared by their adsorption under critical micelle concentrations. It is found that Pluronics bind to the surface of metal NPs as a very thin film by the hydrophobic association through poly(propylene oxide) block of the copolymers. The modification increases the colloidal stability of NPs with increasing hydrophilic-lipophilic balance of Pluronics in the order of L121, F127, and F68. In order to investigate the potentials of polymer coated noble metal NPs as surface-enhanced Raman spect . . .roscopy (SERS) probes, fluorescent dyes and doxorubicin are used as model compounds. It is found that Pluronic component promotes the adsorption of these compounds on the composite NPs resulting in a considerable increase of Raman signal. This effect is attributed to increased concentration of the analyte molecules on the composite surface due to the hydrophobic and charge-charge interactions between the analytes and the Pluronic coat, and the stabilization of NPs by poly(ethylene oxide) blocks. The copolymer coated AgNPs show higher SERS activity than the counterparts prepared with AuNPs. Among the prepared composites, the AgNPs modified with Pluronic F127 containing extended poly(propylene oxide) and poly(ethylene oxide) blocks exhibit maximal Raman activity using rhodamine 6G (Rh6G) with a EF of 9.04 - 106. The results show that the developed Pluronic-based SERS probes can be used for sensitive and selective analysis of organic analytes. © 2009 American Chemical Society Daha fazlası Daha az

Surface-enhanced Raman scattering as an emerging characterization and detection technique

Çulha, Mustafa | Cullum, B. | Lavrik, N. | Klutse, C.K.

Review | 2012 | Journal of Nanotechnology , pp.5153 - 5159

While surface-enhanced Raman spectroscopy (SERS) has been attracting a continuously increasing interest of scientific community since its discovery, it has enjoyed a particularly rapid growth in the last decade. Most notable recent advances in SERS include novel technological approaches to SERS substrates and innovative applications of SERS in medicine and molecular biology. While a number of excellent reviews devoted to SERS appeared in the literature over the last two decades, we will focus this paper more specifically on several promising trends that have been highlighted less frequently. In particular, we will briefly overview s . . .trategies in designing and fabricating SERS substrates using deterministic patterning and then cover most recent biological applications of SERS. Copyright © 2012 Mustafa Culha et al Daha fazlası Daha az

Label-free detection of proteins from self-assembled protein-silver nanoparticle structures using surface-enhanced raman scattering

Kahraman, M. | Sur, I. | Çulha, Mustafa

Article | 2010 | Analytical Chemistry82 ( 18 ) , pp.7596 - 7602

Proteins are one of the most versatile groups of molecules with vital functional roles in living systems. Their enormous diversity and structural flexibility make the detection of these molecules a challenging task. A simple and sensitive label-free protein detection method based on assembly of proteins and colloidal silver nanoparticles (AgNPs) on surfaces and surface-enhanced Raman scattering (SERS) is reported. The SERS spectra from the assembled AgNP/protein films show excellent reproducibility and high quality regardless of the proteins' charge status and size. A detection limit down to 0.5 µg/mL for three acidic proteins; BSA, . . . catalase and pepsin, and three basic proteins; cytochrome c, avidin and lysozyme, is easily achieved. The minimum improvement in detection limit is more than 1 order of magnitude compared to the previously reported detection limits using the technique and the approach has the potential for label-free protein detection and identification. © 2010 American Chemical Society Daha fazlası Daha az

Simultaneous Intracellular Detection of Plasmonic and Non-Plasmonic Nanoparticles Using Dark-Field Hyperspectral Microscopy

Akhatova, F. | Danilushkina, A. | Kuku, G. | Saricam, M. | Çulha, Mustafa | Fakhrullin, R.

Article | 2018 | Bulletin of the Chemical Society of Japan91 ( 11 ) , pp.1640 - 1645

Herein we report the detection and differentiation of plasmonic and non-plasmonic nanoparticles simultaneously administered to A549 lung epithelium cells using dark-field microscopy and hyperspectral imaging. Reflectance spectra-based hyperspectral mapping and image analysis allows for the effective quasi-quantitative identification of nanomaterials in cultured human cells. © 2018 The Chemical Society of Japan.

Optical studies of semiconductor Quantum Dots

Yükselici, H. | Allahverdi, C. | Aşikoglu, A. | Ünlü, H. | Baysal, A. | Çulha, Mustafa | Athalin, H.

Article | 2013 | NanoScience and Technology77 , pp.101 - 117

Optical absorption (ABS), steady-state photoluminescence (PL), resonant Raman, and photoabsorption (PA) spectroscopies are employed to study quantumsize effects in II-VI semiconductor quantum dots (QDs) grown in glass samples. We observe a size-dependent shift in the energetic position of the first exciton peak and have examined the photoinduced evolution of the differential absorption spectra. The Raman shifts of the phonon modes are employed to monitor stoichiometric changes in the composition of the QDs during growth. Two sets of glass samples were prepared from color filters doped with CdSxSe1-xand ZnxCd1-xTe. We analyze the opt . . .ical properties of QDs through the ABS, PL, resonant Raman, and PA spectroscopies. The glass samples were prepared from commercially available semiconductor doped filters by a two-step thermal treatment. The average size of QDs is estimated from the energetic position of the first exciton peak in the ABS spectrum. A calculation based on a quantized-state effective mass model in the strong confinement regime predicts that the average radius of QDs in the glass samples ranges from 2.9 to 4.9 nm for CdTe and from 2.2 to 9.3 nm for CdS0:08Se0:92. We have also studied the nonlinear optical properties of QDs by reviewing the results of size-dependent photoinduced modulations in the first exciton band of CdTe QDs studied by PA spectroscopy. © Springer-Verlag Berlin Heidelberg 2013 Daha fazlası Daha az

Towards PCR-free mutation detection based on surface-enhanced Raman scattering

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 , pp.101 - 117

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

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