Li-Doped ZnO Nanoparticles as Novel Direct Generator of Singlet Oxygen for Potential Photodynamic Therapy Applications

2015 ◽  
Vol 1784 ◽  
Author(s):  
Milton A. Martínez Julca ◽  
Ivonnemary Rivera ◽  
Oscar Perales-Pérez ◽  
Sonia Bailón ◽  
Melina Pérez
Keyword(s):  
Photodynamic Therapy ◽  
Singlet Oxygen ◽  
Zno Nanoparticles ◽  
Band Gap Energy ◽  
Shallow Donor ◽  
Emission Peak ◽  
Ros Generation ◽  
Trap States ◽  
Li Doping ◽  
Doped Zno

ABSTRACTPhotodynamic therapy (PDT) is an alternative to traditional cancer treatments. This approach involves the use of photosensitizer (PS) agents and their interaction with light. As a consequence, cytotoxic reactive oxygen species (ROS) are generated that, in turn will destroy tumors. On the other hand, ZnO is a biocompatible, nontoxic, and biodegradable material with the capability to generate ROS, specifically singlet oxygen (SO), which makes this material a promising candidate for 2-photon PDT. Doping ZnO with Li species is expected to induce defects in the host oxide structure that favors the formation of trap states that should affect the electronic transitions related to the generation of SO. The present work reports the effect of the level of Li-doping on the ZnO structure and its capability to generate SO. Li-doped ZnO nanoparticles were synthesized under size-controlled conditions using a modified version of the polyol method. XRD measurements confirmed the development of well-crystallized ZnO Wurtzite; the average crystallite sizes ranged between 13.3nm and 14.2 nm, with an increase in Li content. The corresponding band gap energy values, estimated from UV-vis measurements, decreased from 3.33 to 3.25 eV. Photoluminescence (PL) measurements of Li-ZnO revealed the presence of emission peaks centered on 363nm, 390nm, and 556 nm; these emission peaks correspond to the exciton emission, transition of shallow donor levels near of the conduction band to valence band such as interstitial Zn, and oxygen vacancies, respectively. The observed increase of the emission intensity of the 390 nm emission peak, relative to the intensity of the main emission peak at 363nm, was attributed to the promote of trap states due to interstitial Zn or Li-incorporation into the host oxide lattice. SO measurements evidenced the enhancing effect of the Li concentration on the capability of the doped ZnO to generate this species. This Li-dependence of SO generation can be attributed to the enhancement of the concentration of trap states in the host ZnO, as suggested by PL measurements. Accordingly, Li-ZnO would become cytotoxic to cancer cells via photo-induced ROS generation enabling this nanomaterial to be considered as a potential direct PS agent for the 2-photon PDT route.

A study on Cu and Ag doped ZnO nanoparticles for the photocatalytic degradation of brilliant green dye: synthesis and characterization

2016 ◽  
Vol 74 (6) ◽  
pp. 1426-1435 ◽  
Author(s):  
A. Gnanaprakasam ◽  
V. M. Sivakumar ◽  
M. Thirumarimurugan
Keyword(s):  
Zno Nanoparticles ◽  
Brilliant Green ◽  
Hexagonal Wurtzite Structure ◽  
Band Gap Energy ◽  
Precipitation Method ◽  
Zno Nps ◽  
Absorption Bands ◽  
Sem Images ◽  
Xrd Diffraction ◽  
Doped Zno

Novel polyvinyl pyrrolidone capped pure, Ag (1–3%) and Cu doped (1–3%) zinc oxide (ZnO) nanoparticles (NPs) were successfully synthesized via the co-precipitation method. The synthesized NPs were characterized by UV-visible spectrophotometry, X-ray diffraction (XRD), energy dispersive spectroscopy (EDS) and field emission scanning electron microscopy (FE-SEM). Compared to pure ZnO, the absorption bands of Ag and Cu doped ZnO NPs were shifted and, further, the band gap energy was also decreased which confirms the incorporation of Ag and Cu into the ZnO lattice. The XRD diffraction peak confirms that all the synthesized compounds are found to be of highly crystalline hexagonal wurtzite structure. In addition, the presence of Ag and Cu in the ZnO NPs was further evidenced from EDS analysis. FE-SEM images established the morphology of the doped ZnO NPs which was not affected by the addition of Ag and Cu. The photocatalytic activity of undoped, Ag doped (1–3%) and Cu doped (1–3%) ZnO NPs were tested with brilliant green dye under UV irradiation. Degradation study reveals that doping has a distinct effect on the photocatalytic behavior of ZnO NPs. In addition to that, kinetic, thermodynamic and reusability studies have been performed for the 2% Ag doped ZnO NPs.

scholarly journals Photocatalytic and Photoluminescence Studies of La, Ce and Dy Co-Doped ZnO Nanoflowers

2021 ◽  
Author(s):  
Syed Irtiqa ◽  
Atikur Rahman
Keyword(s):  
Zno Nanoparticles ◽  
Photocatalytic Performance ◽  
Average Particle Size ◽  
Visible Region ◽  
Solar Spectrum ◽  
Grain Morphology ◽  
Average Particle ◽  
Trap States ◽  
Doped Zno ◽  
Co Doped

Abstract In the present work, ZnO nanoparticles were doped with varying concentration of Lanthanum (La), Cerium (Ce) and Dysprosium (Dy) using a simple and cost effective co-precipitation approach at low temperatures. The resulting powders were calcined at 500 °C for 1 hour using a muffle furnace, to produce La, Ce, Dy co-doped ZnO nanoparticles with varying stoichiometry viz. Zn0.97La0.01Ce0.01Dy0.01O, Zn0.94La0.02Ce0.02Dy0.02O, Zn0.91La0.03Ce0.03Dy0.03O, Zn0.88La0.04Ce0.04 Dy0.04O and Zn0.85La0.05Ce0.05Dy0.05O. This is a simple approach for doping and doesn’t require and complex equipment, harmful chemical or sophisticated machinery. The synthesized powders were characterized using X-Ray diffraction (XRD) and Scanning electron microscopy (SEM) for studying the structure, purity, and grain morphology. The average particle size was calculated using XRD and was found to be 35 nm, it also indicated a hexagonal wurtizite structure with no secondary peaks. A change in morphology from nanorods to nanoflowers was observed as the concentration of dopants increased. Photoluminescence (PL) spectra indicated a red shift in the absorption edge towards the visible region of solar spectrum and this was further confirmed by Diffuse Reflectance Spectra (DRS). The photocatalytic properties of undoped and La, Ce, Dy co-doped ZnO nanoparticles were observed by examining the photodegradation of Rhodamine B dye under UV irradiation. Elimination of dye color indicated the total degradation of organic molecule. The results revealed that ZnO photocatalyst with La, Ce, Dy co-doping concentration Zn0.85La0.05Ce0.05Dy0.05O exhibited the best photocatalytic performance (95%) as compared to undoped ZnO. The improved photocatalytic performance can be attributed to the increased surface oxygen vacancies and adsorption capacity. Delay in recombination of charge carriers due to creation trap states in the bandgap of ZnO further improves the photocatalytic performance of doped samples.

scholarly journals Radiative and Non-Radiative Decay Pathways in Carbon Nanodots toward Bioimaging and Photodynamic Therapy

Nanomaterials ◽  
2021 ◽  
Vol 12 (1) ◽  
pp. 70
Author(s):  
Yujin Kim ◽  
Yoonsang Park ◽  
Seulgi Han ◽  
Wonchan Park ◽  
Mungu Kim ◽  
...  
Keyword(s):  
Photodynamic Therapy ◽  
Radiative Decay ◽  
Near Infrared ◽  
Energy State ◽  
Carbon Nanodots ◽  
Ros Generation ◽  
Trap States ◽  
Different Types ◽  
Energy States

The origin and classification of energy states, as well as the electronic transitions and energy transfers associated with them, have been recognized as critical factors for understanding the optical properties of carbon nanodots (CNDs). Herein, we report the synthesis of CNDs in an optimized process that allows low-temperature carbonization using ethanolamine as the major precursor and citric acid as an additive. The results obtained herein suggest that the energy states in our CNDs can be classified into four different types based on their chemical origin: carbogenic core states, surface defective states, molecular emissive states, and non-radiative trap states. Each energy state is associated with the occurrence of different types of emissions in the visible to near-infrared (NIR) range and the generation of reactive oxygen species (ROS). The potential pathways of radiative/non-radiative transitions in CNDs have been systematically studied using visible-to-NIR emission spectroscopy and fluorescence decay measurements. Furthermore, the bright photoluminescence and ROS generation of these CNDs render them suitable for in vitro imaging and photodynamic therapy applications. We believe that these new insights into the energy states of CNDs will result in significant improvements in other applications, such as photocatalysis and optoelectronics.

Photodegradation of Phenol over Flame-Made Sn-Doped ZnO Nanoparticles

2012 ◽  
Vol 16 ◽  
pp. 97-103 ◽  
Author(s):  
Khatcharin Wetchakun ◽  
Natda Wetchakun ◽  
Burapat Inceesungvorn ◽  
Sukon Phanichphant
Keyword(s):  
Zno Nanoparticles ◽  
Band Gap Energy ◽  
Flame Spray ◽  
Sn Doping ◽  
Zero Order Kinetics ◽  
Deep State ◽  
Flame Condition ◽  
Phenol Photodegradation ◽  
Doped Zno ◽  
Photocatalytic Applications

Undoped ZnO and 0.5−5.0 at.% Sn-doped ZnO nanoparticles were synthesized by flame spray pyrolysis (FSP) using zinc naphthenate and tin (II) 2-ethylhexanoate dissolved in xylene as the precursors under a 5/5 (precursor/oxygen) flame condition. UV-Vis absorption characteristics of the samples were investigated for understanding and relating with the physiochemical characteristics in photocatalytic applications. Kinetic analyzes indicated that the photodegradation rates of phenol could be approximated as pseudo-first-order and zero-order kinetics in the case of undoped ZnO and Sn-doped ZnO nanoparticles respectively, according to the Langmuir-Hinshelwood model. The effect of Sn doping revealed the deterioration of the phenol photodegradation performance over ZnO-based catalysts, possibly due to the formation of a deep state in the ZnO band gap energy.

scholarly journals Tunable Band Gap Energy of Mn-Doped ZnO Nanoparticles Using the Coprecipitation Technique

2014 ◽  
Vol 2014 ◽  
pp. 1-6 ◽  
Author(s):  
Tong Ling Tan ◽  
Chin Wei Lai ◽  
Sharifah Bee Abd Hamid
Keyword(s):  
Zno Nanoparticles ◽  
Band Gap Energy ◽  
Gap Energy ◽  
Morphological Studies ◽  
Coprecipitation Technique ◽  
Doped Zno ◽  
Agglomeration Of Nanoparticles ◽  
Lattice Doping ◽  
Mn Doped ◽  
Tunable Band Gap

A simple coprecipitation technique was introduced to form manganese (Mn) doped on zinc oxide (ZnO) nanoparticles effectively. Based on our morphological studies, it was revealed that mean particle size was increased while bigger agglomeration of nanoparticles could be observed as the amount of concentration of Mn was increased. Interestingly, it was found that the position of the absorption spectra was shifted towards the lower wavelength (UV region) as correlated with the increasing of Mn dopants concentration into ZnO nanoparticles. This result inferred that optimum content of Mn doped into the ZnO nanoparticles was crucial in controlling the visible/UV-responsive of samples. In the present study, 3 mol% of Mn dopants into the ZnO nanoparticles exhibited the better UV as well as visible light-responsive as compared to the other samples. The main reason might be attributed to the modification of electronic structure of ZnO nanoparticles via lattice doping of Mn ions into the lattice, whereas excessive Mn dopants doped on ZnO nanoparticles caused the strong UV-responsive due to the more 3d orbitals in the valence band.

scholarly journals Structural, Morphological, Optical, and Room Temperature Magnetic Characterization on Pure and Sm-Doped ZnO Nanoparticles

2018 ◽  
Vol 2018 ◽  
pp. 1-11 ◽  
Author(s):  
Khalil Badreddine ◽  
I. Kazah ◽  
M. Rekaby ◽  
R. Awad
Keyword(s):  
Crystallite Size ◽  
Zno Nanoparticles ◽  
Room Temperature ◽  
Magnetic Hysteresis ◽  
Hexagonal Wurtzite Structure ◽  
Xrd Analysis ◽  
Peak Shift ◽  
Band Gap Energy ◽  
Ferromagnetic Behavior ◽  
Doped Zno

Nano crystalline Zn1-xSmxO, (0.00 ≤ x ≤ 0.10), were prepared by wet chemical coprecipitation method. The effect of samarium doping on the structural, morphological, optical, and magnetic properties of ZnO nanoparticles was examined by X-ray powder diffraction (XRD), Transmission electron microscopy (TEM), Fourier-transform infrared spectroscopy (FTIR), Ultraviolet-visible spectroscopy (UV) and M-H magnetic hysteresis. XRD analysis showed the hexagonal wurtzite structure of ZnO. The absence of Sm2O3 as separate phase may be attributed to the complete dissolving of samarium in ZnO lattice. The lattice parameters (a and c) of Zn1-xSmxO were calculated and they fluctuated with the increase of Sm doping which indicated that the structure of ZnO was perturbed by the doping of Sm. The crystallite size was computed for all the samples using Debye-Scherrer’s method. The crystallite size decreased with the increase of Sm doping. TEM micrographs revealed that the size and the shape of the ZnO nanocomposites were changed by modifying the doping level of samarium. FTIR analysis spectrum confirmed the formation of ZnO phase and revealed a peak shift between pure and Sm-doped ZnO. The band gap energy and Urbach energy were calculated for Zn1-xSmxO, (0.00 ≤ x ≤ 0.10). The band energy gaps of pure and Sm doped ZnO samples are in the range 2.6–2.98 eV. M-H hysteresis inspection, at room temperature, showed that the pure ZnO exhibited a ferromagnetic behavior incorporated with diamagnetic and paramagnetic contributions. Ferromagnetic behavior was reduced for the doped samples with x=0.01 and x=0.04. The samples with x=0.02 and 0.06 ≤ x ≤ 0.10 tend to be superparamagnetic. The saturation magnetization (Ms), the coercivity (Hc), and the retentivity (Mr) were recorded for Zn1-xSmxO, (0.00 ≤ x ≤ 0.10).

scholarly journals Synthesis and Characterization of Undoped and Magnesium Doped Zinc Oxide Nanoparticles

2021 ◽  
pp. 134-139
Author(s):  
Roxy M S ◽  
Ananthu A ◽  
Sumithranand V B
Keyword(s):  
Zno Nanoparticles ◽  
Band Gap Energy ◽  
Sem Analysis ◽  
Precipitation Method ◽  
Structure Morphology ◽  
Uv Visible ◽  
Doped Zno ◽  
Xrd Patterns ◽  
Co Precipitation ◽  
Mg Doped

Undoped and Mg-doped ZnO nanoparticles were synthesized by co-precipitation method. The synthesized nanoparticles are successfully characterized by XRD, SEM, and UV-visible analysis. The Structure, Morphology, and Optical activity of the synthesized nanoparticle were studied with respect to ZnxMg1-xO (where x= 0, 2.5%M and 7.5%M). The XRD patterns revealed the wurtzite structure for all the nano samples. XRD studies confirmed that the crystalline size increased with increase in Mg content. The surface morphology of the prepared pure and Mg doped ZnO nanoparticles are investigated by SEM analysis. Optical characterization reveals that band gap energy decreases from 3.24 to 3.13 eV with Mg doping. UV-Visible results revealed that absorption underwent a red shift with Mg into ZnO as compared to pure ZnO.

Optical Properties of Photodynamic Therapy Drugs in Different Environments: The Paradigmatic Case of Temoporfin

2020 ◽  
Author(s):  
busenur Aslanoglu ◽  
Ilya Yakavets ◽  
Vladimir Zorin ◽  
Henri-Pierre Lassalle ◽  
Francesca Ingrosso ◽  
...  
Keyword(s):  
Drug Delivery ◽  
Optical Properties ◽  
Photodynamic Therapy ◽  
Minimally Invasive ◽  
Visible Light ◽  
Cancer Treatment ◽  
Singlet Oxygen ◽  
Tumor Cells ◽  
Molecular Oxygen ◽  
Computational Tools

Computational tools have been used to study the photophysical and photochemical features of photosensitizers in photodynamic therapy (PDT) –a minimally invasive, less aggressive alternative for cancer treatment. PDT is mainly based by the activation of molecular oxygen through the action of a photoexcited sensitizer (photosensitizer). Temoporfin, widely known as mTHPC, is a second-generation photosensitizer, which produces the cytotoxic singlet oxygen when irradiated with visible light and hence destroys tumor cells. However, the bioavailability of the mostly hydrophobic photosensitizer, and hence its incorporation into the cells, is fundamental to achieve the desired effect on malignant tissues by PDT. In this study, we focus on the optical properties of the temoporfin chromophore in different environments –in <i>vacuo</i>, in solution, encapsulated in drug delivery agents, namely cyclodextrin, and interacting with a lipid bilayer.

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