Browsing by Subject "Nanoparticle"

Now showing 1 - 20 of 27

Open Access
3D-printed, implantable alginate/CuS nanoparticle scaffolds for local tumor treatment via synergistic photothermal, photodynamic, and chemodynamic therapy
(American Chemical Society, 2023-09-08) Çolak, B.; Cihan, M. C.; Ertaş, Yavuz Nuri
A promising method for treating cancer is localized therapy, which mainly employs hydrogel-based delivery systems. Recently, the capability of 3D printing techniques has been revealed as a promising tool to tackle cancer. In this work, alginate (Alg)-based 3D-printed implantable scaffolds containing bovine serum albumin (BSA)-coated copper sulfide (CuS) nanoparticles, Alg-CuS/BSA, were fabricated for local breast cancer therapy and applied to inhibit tumor development through utilizing synergistic photothermal, photodynamic, and chemodynamic effects. The Alg-CuS/BSA scaffolds were flexible; however, their modulus was significantly lower than that of human breast tissues. Under 808 nm irradiation, the scaffolds demonstrated efficient photothermal, photodynamic, and chemodynamic effects both in vitro and in vivo via improving photothermal transduction and singlet-oxygen formation, and also as Fenton catalysts, the scaffolds produced hydroxyl radicals in the presence of H2O2 within the tumor microenvironment. Without the use of conventional anticancer drugs, the promising tumor treatment of implanted scaffolds can offer potential applications in local cancer treatment and prevent metastasis after surgical removal of tumors.
Open Access
Advances in nanoparticle‐based medical diagnostic and therapeutic techniques
(John Wiley & Sons, 2016-03-11) Sardan, Melis; Özkan, Alper Devrim; Zengin, Aygül; Tekinay, Ayşe B.; Güler, Mustafa O.; Güler, Mustafa O.; Tekinay, Ayşe B.
Advances in modern medicine have eliminated several major causes of human mortality and considerably extended life expectancies around the world; however, this increase in the global age average has also boosted the incidences of age‐associated disorders. These conditions, such as cancer, neurodegenerative disorders, and cardiovascular disease, severely decrease the quality of life for the affected but are highly polymorphic and often difficult to treat. This chapter describes the characteristics of nanoparticle (NP) contrast agents (CAs) proposed for use in medical imaging, and details the surface modification methods used to designate specific targets for their attachment. It then compares their effectiveness and toxicity compared to conventional methods of contrast enhancement, and discusses the contribution that nanoscience has had, and will have, on medical imaging and disease diagnosis at large.
Open Access
Biocompatibility studies on lanthanum oxide nanoparticles
(Royal Society of Chemistry, 2015) Brabu, B.; Haribabu, S.; Revathy, M.; Anitha, S.; Thangapandiyan, M.; Navaneethakrishnan, K. R.; Gopalakrishnan, C.; Murugan, S. S.; Kumaravel, T. S.
Lanthanum oxide nanoparticles (LONP), a rare earth metal oxide, have unique properties that make them a suitable candidate for several biomedical applications. We investigated certain key in vitro and in vivo biocompatibility endpoints on LONP. LONP were cytotoxic in in vitro assays and predominantly exerted their action via release of reactive oxygen species. These nanoparticles were neither irritants nor sensitizers in a rabbit model. LONP extracts did not exert any acute systemic toxicity effects in mice. On the other hand LONP exerted toxicity to the liver following oral administration, suggesting that these particles are absorbed from the gastrointestinal (GI) tract and deposited in the hepatobiliary system. LONP did not induce any mutation in the Ames test both in the presence or absence of S-9. These observations provide a base line biocompatibility and toxicity data on LONP. The current findings will also be useful in defining standards for nanoparticle containing devices. © The Royal Society of Chemistry.
Open Access
Chitosan coated iron-oxide nanoparticle synthesis using a droplet based microfluidic reactor
(IEEE, 2019-06) Wahab, Malik Abdul; Erdem, E. Yegan
A microfluidic reactor for the synthesis of chitosan coated iron-oxide nanoparticles is described. Tapered double T-junction is used to generate droplets of reactants (iron chloride solution and chitosan solution) which were merged using a pillar array. Third reactant ammonia solution is introduced after the mixing of already merged droplets. Ammonia solution initiates the reaction and precipitates are collected at the outlet. Transmission electron microscope (TEM) imaging along with Fourier transform infrared spectroscopy (FTIR) is used to characterize the nanoparticles. These nanoparticles have applications in nano-medicine where they can be used as drug carriers.
Open Access
Dielectrophoresis in microfluidics technology
(2011) Çetin B.; Li, D.
Dielectrophoresis (DEP) is the movement of a particle in a non-uniform electric field due to the interaction of the particle's dipole and spatial gradient of the electric field. DEP is a subtle solution to manipulate particles and cells at microscale due to its favorable scaling for the reduced size of the system. DEP has been utilized for many applications in microfluidic systems. In this review, a detailed analysis of the modeling of DEP-based manipulation of the particles is provided, and the recent applications regarding the particle manipulation in microfluidic systems (mainly the published works between 2007 and 2010) are presented. © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Open Access
Differential charging in x-ray photoelectron spectroscopy: a nuisance or a useful tool?
(American Chemical Society, 2003) Süzer, Şefik
We apply a negative bias to the sample while recording an XPS spectrum to enhance differential (positive) charging. The enhanced differential charging is due to the repulsion of stray electrons from the sample, which normally cause partial neutralization of the poorly conducting samples or regions accumulating positive charging, as a consequence of the photoelectron emission. This enhanced differential charging (obtained by negative biasing) is shown to have the ability to separate otherwise overlapping peaks of PDMS layer from that of the SiO2/Si substrate. Each layer experiences different charging that can be used to derive information related to dielectric properties of the layers, proximity of the atoms within composite multilayers, or both. Hence, differential charging in XPS, which is usually considered as a nuisance, is turned into a useful tool for extracting additional information from nanometer-size surface structures.
Open Access
Enhanced in vivo radiotherapy of breast cancer using gadolinium oxide and gold hybrid nanoparticles
(American Chemical Society, 2023-01-24) Nosrati, H.; Salehiabar, M.; Charmi, J.; Yaray, K.; Ghaffarlou, M.; Balcıoğlu, E.; Ertaş, Yavuz Nuri
Radiation therapy has demonstrated promising effectiveness against several types of cancers. X-ray radiation therapy can be made further effective by utilizing nanoparticles of high-atomic-number (high-Z) materials that act as radiosensitizers. Here, in purpose of maximizing the radiation therapy within tumors, bovine serum albumin capped gadolinium oxide and gold nanoparticles (Gd2O3@BSA-Au NPs) are developed as a bimetallic radiosensitizer. In this study, we incorporate two high-Z-based nanoparticles, Au and Gd, in a single nanoplatform. The radiosensitizing ability of the nanoparticles was assessed with a series of in vitro tests, following evaluation in vivo in a breast cancer murine model. Enhanced tumor suppression is observed in the group that received radiation after administration of Gd2O3@BSA-Au NPs. As a result, cancer therapy efficacy is significantly improved by applying Gd2O3@BSA-Au NPs under X-ray irradiation, as evidenced by studies evaluating cell viability, proliferation, reactive oxygen species production, and in vivo anti-tumor effect.
Open Access
Fast and quick degradation properties of doped and capped ZnO nanoparticles under UV-Visible light radiations
(Elsevier Ltd, 2016) Mittal, M.; Sharma, M.; Pandey, O. P.
Undoped and Manganese (Mn) doped zinc oxide (ZnO) (Zn1- xMnxO, x=0.005, 0.01, 0.015 and 0.02) nanoparticles (NPs) capped with (1.0%) Thioglycerol (TG) has been successfully synthesized by co-precipitation method. Optical and morphological studies have been done for photophysical and structural analysis of synthesized materials. The photocatalytic activity of undoped and Mn doped ZnO NPs were investigated by degradation of crystal violet (CV) dye under UV-Visible light radiations. It has been found that Mn (1.0%) doping concentration is optimal for photophysical and photocatalytic properties. When the pH of as synthesized optimum doped ZnO NPs varied from natural pH i.e. from 6.7 to 8.0 and 10.0, the degradation of CV dye increases from 92% to 95% and 98% in 180min respectively. Further on increasing the pH of optimum doped synthesized NPs to 12.0, almost 100% degradation has been achieved in 150min. Optimum doped photocatalyst synthesized at pH-12.0 has also effectively degraded the CV dye solution in acidic and basic medium thus showed its utility in various industries. However, it has been found that 100% of CV dye quickly degraded in 30min when only 1.0% of hydrogen peroxide (H2O2) was introduced along with optimized NPs synthesized at pH-12. Kinetic studies show that the degradation of CV dye follows pseudo first and second-order kinetic law. Further an industrial anionic polyazo Sirius red F3B (SRF3B) dye has been degraded to 100% with optimized NPs synthesized at pH-12.0 in 15min only.
Open Access
Growth of Ge nanoparticles on SiO2 / Si interfaces during annealing of plasma enhanced chemical vapor deposited thin films
(Elsevier B.V., 2007) Foss, S.; Finstad, T. G.; Dana, A.; Aydınlı, Atilla
Multilayer germanosilicate (Ge:SiO2) films have been grown by plasma enhanced chemical vapor deposition. Each Ge:SiO2 layer is separated by a pure SiO2 layer. The samples were heat treated at 900 °C for 15 and 45 min. Transmission electron microscopy investigations show precipitation of particles in the layers of highest Ge concentration. Furthermore there is evidence of diffusion between the layers. This paper focuses mainly on observed growth of Ge particles close to the interface, caused by Ge diffusion from the Ge:SiO2 layer closest to the interface through a pure SiO2 layer and to the interface. The particles grow as spheres in a direction away from the interface. Particles observed after 15 min anneal time are 4 nm in size and are amorphous, while after 45 min anneal time they are 7 nm in size and have a crystalline diamond type Ge structure.
Open Access
Immunoregulatory activities of nanoparticle-forming oligodeoxynucleotides
(2009) Karatepe, Kutay
Innate immune system is activated by a wide range of microbial by products leading to an immediate immune activation primarily designed to neutralize and control the invading insult. The cells of the innate immune system also instruct the development of antigen-specific adaptive immunity. While TLR9 is triggered by bacterial DNA, extended and over-exuberant immune response poses a threat since it may exacerbate cell and tissue destruction leading to organ failure. Telomeric TTAGGG conserved motifs are previously reported to antagonize TLR mediated events. The down-regulatory effect of these motifs may help to restore the desired homeostatic balance of the immune system. While CpG ODN patterned after bacterial DNA can be harnessed in different clinical settings to provide an advantage to host to resist infectious diseases, control tumor growth or alleviate allergic symptoms, the immunosuppressive telomeric motifs could be effectively applied in controlling systemic anti-inflammatory or autoimmune related disorders. Several challenges exist in the utilization of synthetic ODNs in the clinic. The first challenge is that conventional classes of synthetic ODNs exhibit different properties. K-type ODNs are more effective in proliferation and activation of B cells and DC. D-type ODNs are in nanoparticle forms, lead to anti-viral type I IFN production and mature monocytes into DCs. Of note, the efficacy of these synthetic ODNs is reduced under physiological conditions due to premature clearance and low levels of internalization. Moreover, D-ODNs as one of the most potent IFNα inducing TLR9 ligands possess a large-scale production problem due to 3’polyGruns, which hamper their entry into the clinic. We have designed a novel class of ODN, designated as ODN420, devoid of polyGs that can undergo nanoparticle formation necessary for its IFNα induction. Ex vivo stimulation of mouse splenocytes and in vivo administration of ODN420 have revealed that this ODN exhibits higher immunostimulatory potential and is more stable than most commonly used ODNs due to its nanoparticle-forming ability. Another interesting finding is that ODN420 with the natural phosphodiester (PO) backbone is at least as potent as its more stable counterpart with the modified phosphorothioate backbone. Furthermore, it combines superior properties of conventional classes of K and D-ODNs. These results have been reproduced in human peripheral blood mononuclear cells by various assays. Next, we have analyzed whether this ODN could be utilized as a vaccine adjuvant and an anti-cancer agent with two independent experiments. Our immunization results demonstrate that ODN420 induces a higher level of Th1-mediated response than conventional ODNs and is a promising candidate as a vaccine adjuvant. This response is hampered when ODN420 is used in combination with ODN-A151. In the tumor xenograft model, ODN420 has promoted partial remission of the tumors or delayed the tumor growth. This knowledge will pave the way for more effective immunotherapeutic approaches.
Open Access
InGaN green light emitting diodes with deposited nanoparticles
(Elsevier BV, 2007) Butun, B.; Cesario J.; Enoch, S.; Quidant, R.; Özbay, Ekmel
We grew an InGaN/GaN-based light-emitting diode (LED) wafer by metal-organic chemical vapor deposition (MOCVD), fabricated devices by optical lithography, and successfully deposited ellipsoidal Ag nano-particles by way of e-beam lithography on top. The diodes exhibited good device performance, in which we expected an enhancement of the radiated intensity by the simulations and emission measurements. The obtained results showed the feasibility of plasmon-assisted LED emission enhancement.
Open Access
Investigation of novel RNAi and nanoparticle approaches for their anti-proliferative and drug-sensitizing effects in breast cancer
(2017-08) Jahja, Ermira
Drug resistivity remains a major challenge in treating different cancer types. Among several strategies adapted to increase drug sensitivity in breast cancer cells, in the present thesis I studied an RNAi molecule targeting cholinergic receptor nicotinic alpha 5 subunit (CHRNA5) and a red-emitting oligomer nanoparticle, the two agents which I experimentally identified as negative regulators of cell proliferation. Cholinergic signaling is implicated in several different pathologies including cancer. Nicotinic acetylcholine receptors (nAChRs) are shown to be involved in regulation of cell proliferation, however they are mainly studied as mediators of nicotinic activity. CHRNA5 subunit has been shown to have roles in acetylcholine (ACh) production/stability, drug addiction and susceptibility to lung cancer. Few studies of lung and gastric cancers as well as high throughput RNAi screens show CHRNA5 as a modulator of cell proliferation. In the present study multiple CHRNA5 isoforms were cloned from MCF7 breast cancer cells (ER positive, TP53 positive) as in the case of lung cancer; moreover, a significant antimitotic effect of CHRNA5 RNAi application was demonstrated in MCF7 breast cancer cells. Similar effect of CHRNA5 silencing was only partially observed in BT-20 and MDA-MB-231 cells (ER negative, P53 mutant), yet in a seeding density-dependent manner. For the first time in literature the transcriptomic changes associated with CHRNA5 RNAi in the MCF7 cells were studied by microarrays from which differentially expressed gene lists were used to obtain the affected pathways. Additional assays confirmed the reduction in cell viability, DNA synthesis, G1 growth arrest, and changes in cytoskeleton complementing the microarray studies. Use of camptothecin (CPT) and doxorubicin (DOXO) in the absence or presence of CHRNA5 siRNA in MCF7, led to identification of CHRNA5’s role in drug sensitivity. Comparisons between CHRNA5 siRNA and public microarray datasets revealed common genes/networks between topoisomerase (TOPO)/cyclin-dependent kinase (CDK) inhibitors and CHRNA5 depletion profile in MCF7 cells. mRNA-miRNA network analysis of differentially expressed common gene sets between TOPO inhibitors and CHRNA5 RNAi treatment identified potential common regulatory miRNAs. In an independent study the anti-cancer as well as drug sensitivity associated effects of a novel CB7-capped, red-emitting conjugated oligomer nanoparticle (Red-CON) were characterized in MCF7 and MDA-MB-231 cells. Red-CON in its encapsulated form exhibited low toxicity and good efficacy as a drug delivery system. This nanoparticle formulation might serve well for future clinical and less toxic chemotherapeutic regimens.
Open Access
Mesoporous metallic rhodium nanoparticles
(Nature Publishing Group, 2017) Jiang B.; Li C.; Dag, Ö.; Abe, H.; Takei, T.; Imai, T.; Hossain, M. S. A.; Islam, M. T.; Wood, K.; Henzie, J.; Yamauchi, Y.
Mesoporous noble metals are an emerging class of cutting-edge nanostructured catalysts due to their abundant exposed active sites and highly accessible surfaces. Although various noble metal (e.g. Pt, Pd and Au) structures have been synthesized by hard- and soft-templating methods, mesoporous rhodium (Rh) nanoparticles have never been generated via chemical reduction, in part due to the relatively high surface energy of rhodium (Rh) metal. Here we describe a simple, scalable route to generate mesoporous Rh by chemical reduction on polymeric micelle templates [poly(ethylene oxide)-b-poly(methyl methacrylate) (PEO-b-PMMA)]. The mesoporous Rh nanoparticles exhibited a ∼1/42.6 times enhancement for the electrocatalytic oxidation of methanol compared to commercially available Rh catalyst. Surprisingly, the high surface area mesoporous structure of the Rh catalyst was thermally stable up to 400 °C. The combination of high surface area and thermal stability also enables superior catalytic activity for the remediation of nitric oxide (NO) in lean-burn exhaust containing high concentrations of O 2.
Open Access
Metal nanoring and tube formation on carbon nanotubes
(American Physical Society, 2002) Bagci, V. M. K.; Gülseren, O.; Yildirim, T.; Gedik, Z.; Ciracil, S.
The structural and electronic properties of aluminum-covered single-wall carbon nanotubes (SWNT's) are studied from first principles for a large number of coverages. Aluminum-aluminum interaction, that is stronger than aluminum-tube interaction, prevents uniform metal coverage, and hence gives rise to the clustering. However, a stable aluminum ring and aluminum nanotube with well defined patterns can also form around the semiconducting SWNT's and lead to metallization. The persistent current in the Al nanoring is discussed to show that a high magnetic field can be induced at the center of SWNT.
Open Access
Novel nanocomposite coatings of nanoparticles
(2011) Toru, Refik Sina
Incorporating nanoparticles into nanocomposite thin-films enables coatings with multi-functionality depending on the particle type and size, and the film morphology. These multiple functions may include, for example, combinations of photocatalysis, hydrophobicity, scratch resistance, and antibacterial property. Here we proposed and demonstrated a new encapsulation nanocomposite with controllable refractive index and potentially additional functional properties for coating photonic devices, for instance, light-emitting diodes (LEDs). To design and implement this nanocomposite coating with tunable refractive index, we employed TiO2 nanoparticles of various diameters because of their relatively high refractive index. We embedded these nanoparticles in our encapsulation sol-gel material during synthesis. In addition, we incorporated several polymerforming chemicals during synthesis to control additional functions such as hydrophobicity and scratch resistance. We used characterization tools of atomic force microscopy, refractometry, contact angle measurement, and scanning electron microscopy to study material properties.
Open Access
Plasmonics: merging photonics and electronics at nanoscale dimensions
((AAAS) American Association for the Advancement of Science, 2006) Özbay, Ekmel
Electronic circuits provide us with the ability to control the transport and storage of electrons. However, the performance of electronic circuits is now becoming rather limited when digital information needs to be sent from one point to another. Photonics offers an effective solution to this problem by implementing optical communication systems based on optical fibers and photonic circuits. Unfortunately, the micrometer-scale bulky components of photonics have limited the integration of these components into electronic chips, which are now measured in nanometers. Surface plasmon-based circuits, which merge electronics and photonics at the nanoscale, may offer a solution to this size-compatibility problem. Here we review the current status and future prospects of plasmonics in various applications including plasmonic chips, light generation, and nanolithography.
Open Access
Reduced density matrix approach to phononic dissipation in friction
(2000) Özpineci, A.; Leitner, D. M.; Çıracı, Salim
Understanding mechanisms for energy dissipation from nanoparticles in contact with large samples is a central problem in describing friction microscopically. Calculation of the reduced density matrix appears to be the most suitable method to study such systems that are coupled to a large environment. In this paper, the time evolution of the reduced density matrix has been evaluated for an arbitrary system coupled to a heat reservoir. The formalism is then applied to study the vibrational relaxation following the stick-slip motion of an asperity on a surface. The frequency and temperature dependence of the relaxation time is also determined. Predictions of the reduced density matrix are compared with those obtained by using the Golden Rule approach.
Open Access
Resonant harmonic response in tapping-mode atomic force microscopy
(American Physical Society, 2004) Sahin, O.; Quate, C. F.; Solgaard, O.; Atalar, Abdullah
Higher harmonics in tapping-mode atomic force microscopy offers the potential for imaging and sensing material properties at the nanoscale. The signal level at a given harmonic of the fundamental mode can be enhanced if the cantilever is designed in such a way that the frequency of one of the higher harmonics of the fundamental mode (designated as the resonant harmonic) matches the resonant frequency of a higher-order flexural mode. Here we present an analytical approach that relates the amplitude and phase of the cantilever vibration at the frequency of the resonant harmonic to the elastic modulus of the sample. The resonant harmonic response is optimized for different samples with a proper design of the cantilever. It is found that resonant harmonics are sensitive to the stiffness of the material under investigation.
Open Access
Solid-solution of Cd(formula)Zn(formula)S nanocrystals in the channels of mesostructured silica films
(2006) Akdoğan, Yaşar
Mesostructured silica can be used as a reaction medium to produce solidsolution of Cd1-xZnxS nanocrystals as thin films. These films were synthesized from oligo(ethylene oxide) non-ionic surfactant (CH3(CH2)11(OCH2CH2)10OH, (C12EO10)), cadmium and zinc nitrate salts ([Cd(H2O)4](NO3)2 and [Zn(H2O)6](NO3)2), water, and tetramethylorthosilicate (TMOS, as silica source) mixtures using a liquid crystalline templating (LCT) approach and metal containing liquid crystalline (MLC) mesophase. Metal ion to surfactant mole ratio was 1.0 which determines the stability and structure of the mesostructured silica. The mesostructured silica film has a 3D hexagonal structure with oriented channels. The silica pore size can be controlled by controlling ageing temperature and time. The pore diameter of the silica channels that aged at room temperature (RT) for two days is 4.7 nm and the one aged at 2500 C for 30 minutes is 3.3 nm. Cd(II) and Zn(II) incorporated film samples can be reacted at RT under H2S atmosphere to produce zinc blend, Cd1-xZnxS nanocrystals (nano-Cd1-xZnxS-meso-SiO2) in the channels of the mesostructured silica. The band gaps of the nano-Cd1- xZnxS-meso-SiO2 vary between 2.6 eV for CdS and 4.1 eV for ZnS. The Cd (II) rich nanoparticles are larger (4.4 nm) than Zn (II) rich nanoparticles (3.1 nm). The silica wall thickness that can be controlled by ageing at different temperatures confines the growth of the Cd1-xZnxS nanocrystals in the pores. By controlling the size of the silica channel between 4.7 and 3.3 nm, one can control the band-gap of the CdS nanocrystals between 2.6 and 2.8 eV.
Open Access
Structure and nanotribology of thermally deposited gold nanoparticles on graphite
(2015) Cihan, Ebru
Forming a complete understanding of the physical mechanisms that govern friction on the nanometer and atomic scales is an ongoing endeavor for scientists from various disciplines. While atomic force microscopy (AFM) has proven to be invaluable for the detailed study of nano-scale frictional properties associated with various surfaces, issues related to the precise characterization of the contact formed by the probe tip and the sample surface remain largely unsolved. In recent years, an alternative approach to nanotribology experiments has involved the lateral manipulation of well-characterized nanoparticles on sample surfaces via AFM and the measurement of associated frictional forces. In line with this idea, ambient-condition structural/nanotribological characterization and nano-manipulation experiments involving gold nanoparticles (AuNP) thermally deposited on highly oriented pyrolytic graphite (HOPG) are presented in this thesis. The effect of deposition amount on thin film morphology is discussed and post- deposition annealing procedure in terms of different annealing temperatures and times are tackled in order to characterize AuNP formation on HOPG. The morphology and distribution of AuNPs on HOPG are studied via scanning electron microscopy (SEM) while the confirmation of AuNP crystallinity via transmission electron microscopy (TEM) is also described. Topographical characterization of the resulting AuNP/HOPG material system performed via contact-mode AFM is demonstrated. Lateral force measurements are also presented, in terms of the dependence of friction force on normal load as well as the dependence of friction force increase at AuNP edges on normal load and particle height. Subsequent to comprehensive structural and frictional characterization, the results of nano-manipulation experiments performed on AuNPs on the HOPG substrate are reported and it is observed that AuNPs experience remarkably low frictional forces during sliding. A detailed study of friction with respect to contact area firmly confirms the occurrence of structurally lubric sliding under ambient conditions for this material system. This result constitutes the first observation of structurally lubric sliding under ambient conditions between different materials in the scientific literature.