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1.
Anticancer Agents Med Chem ; 24(1): 50-57, 2024.
Article in English | MEDLINE | ID: mdl-37921146

ABSTRACT

BACKGROUND: Numerous studies have proven the efficacy and safety of natural products, and are widely used as attractive cancer treatments. The investigation of effective natural products for improving cancer treatment is a promising strategy. Combination treatment with radiosensitizers and radiotherapy (RT) is considered necessary for therapeutic improvement in head and neck squamous cell carcinoma(HNSCC). OBJECTIVE: This study aims to investigate whether Ephedra sinica (ES) extract could induce selective cell death in cancer cells and serve as a radiosensitizer for HNSCC. METHODS: HNSCC cells were pretreated with ES extract before radiation, and the radiosensitizing activity was assessed using a colony formation assay. Radiation-induced cell death was evaluated using an annexinV-FITC assay. Western blotting was performed to confirm cell death-related gene expression, including apoptosis and necrosis markers. RESULTS: ES extract significantly inhibited HNSCC cell viability (FaDu and SNU1076), while having minimal effect on normal HaCaT cells. When HNSCC cells were irradiated with 2, 4, or 8 Gy and cultured with ES extract (25 µg/mL), they exhibited increased radiation sensitivity compared to non-treated cells. The combination of ES extract and radiation resulted in increased cell death compared to non-treated, ES-treated, or irradiated cells. The apoptosis marker BAX and necrosis marker p-MLKL expression levels were also elevated following the combination treatment. CONCLUSION: ES extract demonstrated significant cytotoxic potential in HNSCC cells without affecting normal cells. It enhanced the radiosensitivity of HNSCC cells by upregulating BAX and p-MLKL expression, leading to increased cell death. These results suggest ES extract exhibits a potential radiosensitizing capacity in HNSCC.


Subject(s)
Biological Products , Carcinoma, Squamous Cell , Ephedra sinica , Head and Neck Neoplasms , Radiation-Sensitizing Agents , Humans , Squamous Cell Carcinoma of Head and Neck/drug therapy , bcl-2-Associated X Protein/genetics , Carcinoma, Squamous Cell/drug therapy , Head and Neck Neoplasms/drug therapy , Head and Neck Neoplasms/radiotherapy , Cell Line, Tumor , Cell Death , Apoptosis , Radiation-Sensitizing Agents/pharmacology , Radiation-Sensitizing Agents/therapeutic use , Necrosis , Biological Products/pharmacology , Protein Kinases/pharmacology , Protein Kinases/therapeutic use
2.
Cancer Genomics Proteomics ; 18(5): 675-684, 2021.
Article in English | MEDLINE | ID: mdl-34479919

ABSTRACT

BACKGROUND: We propose a novel prognostic biomarker-based strategy for increasing the efficacy of radiotherapy (RT) in head and neck squamous cell carcinoma (HNSCC). MATERIALS AND METHODS: We identified genes associated with superoxide dismutase 2 (SOD2) and nuclear factor erythroid-2-related factor 2 (NRF2) from gene-expression data of The Cancer Genome Atlas (TCGA) by calculating Pearson correlation. Patients were divided into two groups using hierarchical clustering. Colony-formation assay was performed to determine radioresistance in HNSCC cell line CAL27. Pathway analysis was conducted using The Database for Annotation, Visualization and Integrated Discovery (DAVID). RESULTS: We developed a 49-gene signature with SOD2- and NRF2-associated genes. Using mRNA expression data for the 49-gene signature, we performed hierarchical clustering to stratify patients into two subtypes, subtype A and B. In the TCGA cohort, subgroup A demonstrated a better prognosis than subgroup B in patients who received RT. The signature robustness was evaluated in other independent cohorts. We showed through colony-formation assay that depletion of SOD2 or NRF2 leads to increased radiosensitivity. CONCLUSION: We identified and validated a robust gene signature of SOD2- and NRF2-associated genes in HNSCC and confirmed their link to radioresistance using in vitro assay, providing a novel biomarker for the evaluation of HNSCC prognosis.


Subject(s)
NF-E2-Related Factor 2/metabolism , Squamous Cell Carcinoma of Head and Neck/genetics , Superoxide Dismutase/metabolism , Female , Humans , Male , Middle Aged , Prognosis , Squamous Cell Carcinoma of Head and Neck/pathology
3.
Cancer Manag Res ; 11: 7103-7110, 2019.
Article in English | MEDLINE | ID: mdl-31440097

ABSTRACT

PURPOSE: We evaluated the effects of diabetes mellitus (DM) and DM-related serologic factors (HbA1c and fasting glucose) on the development of radiation pneumonitis in patients with lung cancer. METHODS: We retrospectively analyzed the clinical data of 123 patients with lung cancer treated with radiotherapy. Radiation pneumonitis was scored according to the toxicity criteria of the Radiation Therapy Oncology Group. We used binary logistic regression analysis to find significant predictive factors for the development of grade ≥3 radiation pneumonitis. RESULTS: On univariable analysis, V20, mean lung dose, DM, HbA1c, and fasting glucose level were significantly associated with the development of grade ≥3 radiation pneumonitis. On multivariable analysis, V20, mean lung dose, DM, HbA1c, and fasting glucose level remained significant predictive factors for grade ≥3 radiation pneumonitis. The incidence of grade ≥3 radiation pneumonitis was 44.4% in patients with DM and 20.7% in patients without DM. The incidence of grade ≥3 radiation pneumonitis was 12.7% for HbA1c level ≤6.15% and 41.5% for HbA1c level >6.15%. The incidence of grade ≥3 radiation pneumonitis was 17.2% for fasting glucose level ≤121 mg/dL and 35.5% for fasting glucose level >121 mg/dL. CONCLUSION: DM, HbA1c, and fasting glucose level are significant predictive factors for the development of grade ≥3 radiation pneumonitis in patients with lung cancer. Patients with DM, patients who have HbA1c >6.15%, and patients who have fasting glucose >121 mg/dL should be treated with greater caution.

4.
Acta Oncol ; 57(10): 1359-1366, 2018 Oct.
Article in English | MEDLINE | ID: mdl-30004264

ABSTRACT

BACKGROUND: The aim of the present study was to verify the dosimetric accuracy of two-dimensional (2D) in vivo rectal dosimetry using an endorectal balloon (ERB) with unfoldable EBT3 films for high-dose-rate (HDR) brachytherapy for cervical cancer. The clinical applicability of the technique was discussed. MATERIAL AND METHODS: ERB inflation makes the EBT3 films unrolled, whereas its deflation makes them rolled. Patient-specific quality assurance (pQA) tests were performed in 20 patient plans using an Ir-192 remote afterloading system and a water-filled cervical phantom with the ERB. The dose distributions measured in ERBs were compared with those of the treatment plans. RESULTS: The absolute dose profiles measured by the ERBs were in good agreement with those of treatment plans. The global gamma passing rates were 96-100% and 91-100% over 20 pQAs under the criteria of 3%/3 mm and 3%/2 mm, respectively, with a 30% low-dose threshold. Dose-volume histograms of the rectal wall were obtained from the measured dose distributions and showed small volume differences less than 2% on average from the patients' plans over the entire dose interval. The positioning error of the applicator set was detectable with high sensitivity of 12% dose area variation per mm. Additionally, the clinical applicability of the ERB was evaluated in volunteers, and none of them felt any pain when the ERB was inserted or removed. CONCLUSIONS: The 2D in vivo rectal dosimetry using the ERB with EBT3 films was effective and might be clinically applicable for HDR brachytherapy for cervical and prostate cancers to monitor treatment accuracy and consistency as well as to predict rectal toxicity.


Subject(s)
Brachytherapy/methods , Rectum/radiation effects , Uterine Cervical Neoplasms/radiotherapy , Female , Humans , Phantoms, Imaging , Radiotherapy Dosage
6.
Sci Rep ; 6: 37848, 2016 11 29.
Article in English | MEDLINE | ID: mdl-27897205

ABSTRACT

Traversing proton beam-irradiated, mid/high-Z nanoparticles produce site-specific enhancement of X-ray photon-electron emission via the Coulomb nanoradiator (CNR) effect, resulting in a nano- to micro-scale therapeutic effect at the nanoparticle-uptake target site. Here, we demonstrate the uptake of iron oxide nanoparticles (IONs) and nanoradiator-mediated, site-specific thrombolysis without damaging the vascular endothelium in an arterial thrombosis mouse model. The enhancement of low-energy electron (LEE) emission and reactive oxygen species (ROS) production from traversing proton beam-irradiated IONs was examined. Flow recovery was only observed in CNR-treated mice, and greater than 50% removal of the thrombus was achieved. A 2.5-fold greater reduction in the thrombus-enabled flow recovery was observed in the CNR group compared with that observed in the untreated ION-only and proton-only control groups (p < 0.01). Enhancement of the X-ray photon-electron emission was evident from both the pronounced Shirley background in the electron yield and the 1.2- to 2.5-fold enhanced production of ROS by the proton-irradiated IONs, which suggests chemical degradation of the thrombus without potent emboli.


Subject(s)
Ferric Compounds/administration & dosage , Metal Nanoparticles/chemistry , Proton Therapy/instrumentation , Thrombosis/therapy , Animals , Combined Modality Therapy , Disease Models, Animal , Dose-Response Relationship, Radiation , Ferric Compounds/chemistry , Metal Nanoparticles/administration & dosage , Mice , Nanotechnology , Radiation Dosage , Reactive Oxygen Species/metabolism
7.
Sci Rep ; 6: 30111, 2016 07 21.
Article in English | MEDLINE | ID: mdl-27439777

ABSTRACT

Non-alcoholic fatty liver disease (NAFLD) is one of the most frequent causes of liver disease and its prevalence is a serious and growing clinical problem. Caloric restriction (CR) is commonly recommended for improvement of obesity-related diseases such as NAFLD. However, the effects of CR on hepatic metabolism remain unknown. We investigated the effects of CR on metabolic dysfunction in the liver of obese diabetic db/db mice. We found that CR of db/db mice reverted insulin resistance, hepatic steatosis, body weight and adiposity to those of db/m mice. (1)H-NMR- and UPLC-QTOF-MS-based metabolite profiling data showed significant metabolic alterations related to lipogenesis, ketogenesis, and inflammation in db/db mice. Moreover, western blot analysis showed that lipogenesis pathway enzymes in the liver of db/db mice were reduced by CR. In addition, CR reversed ketogenesis pathway enzymes and the enhanced autophagy, mitochondrial biogenesis, collagen deposition and endoplasmic reticulum stress in db/db mice. In particular, hepatic inflammation-related proteins including lipocalin-2 in db/db mice were attenuated by CR. Hepatic metabolomic studies yielded multiple pathological mechanisms of NAFLD. Also, these findings showed that CR has a therapeutic effect by attenuating the deleterious effects of obesity and diabetes-induced multiple complications.


Subject(s)
Body Weight , Caloric Restriction , Liver/metabolism , Non-alcoholic Fatty Liver Disease/diet therapy , Animals , Chromatography, Liquid , Collagen/metabolism , Endoplasmic Reticulum Stress , Ketones/metabolism , Lipid Metabolism , Lipogenesis , Mass Spectrometry , Metabolomics , Mice , Non-alcoholic Fatty Liver Disease/metabolism , Proton Magnetic Resonance Spectroscopy , Triglycerides/biosynthesis
8.
Oncotarget ; 7(30): 48562-48576, 2016 Jul 26.
Article in English | MEDLINE | ID: mdl-27391070

ABSTRACT

Abnormal tumor cell metabolism is a consequence of alterations in signaling pathways that provide critical selective advantage to cancer cells. However, a systematic characterization of the metabolic and signaling pathways altered in cancer stem-like cells (CSCs) is currently lacking. Using nuclear magnetic resonance and mass spectrometry, we profiled the whole-cell metabolites of a pair of parental (P-231) and stem-like cancer cells (S-231), and then integrated with whole transcriptome profiles. We identified elevated NAAD+ in S-231 along with a coordinated increased expression of genes in Wnt/calcium signaling pathway, reflecting the correlation between metabolic reprogramming and altered signaling pathways. The expression of CD38 and ALP, upstream NAAD+ regulatory enzymes, was oppositely regulated between P- and S-231; high CD38 strongly correlated with NAADP in P-231 while high ALP with NAAD+ levels in S-231. Antagonizing Wnt activity by dnTCF4 transfection reversed the levels of NAAD+ and ALP expression in S-231. Of note, elevated NAAD+ caused a decrease of cytosolic Ca2+ levels preventing calcium-induced apoptosis in nutrient-deprived conditions. Reprograming of NAD+ metabolic pathway instigated by Wnt signaling prevented cytosolic Ca2+ overload thereby inhibiting calcium-induced apoptosis in S-231. These results suggest that "oncometabolites" resulting from cross talk between the deranged core cancer signaling pathway and metabolic network provide a selective advantage to CSCs.


Subject(s)
Cellular Reprogramming , NADP/analogs & derivatives , NAD/metabolism , Neoplastic Stem Cells/pathology , Wnt Signaling Pathway , ADP-ribosyl Cyclase 1/metabolism , Alkaline Phosphatase/metabolism , Calcium/metabolism , Cell Line, Tumor , Cytosol/metabolism , Flow Cytometry , Gene Expression Profiling , Humans , In Situ Nick-End Labeling , Magnetic Resonance Spectroscopy , Mass Spectrometry , Membrane Glycoproteins/metabolism , Metabolomics/methods , NADP/metabolism , Spheroids, Cellular , Transcription Factor 4/genetics , Transfection
9.
Radiother Oncol ; 120(2): 327-32, 2016 08.
Article in English | MEDLINE | ID: mdl-27222297

ABSTRACT

BACKGROUND AND PURPOSE: The present study aims to investigate the feasibility of two-dimensional (2D) in vivo rectal dosimetry using an endorectal balloon for the radiotherapy of prostate cancer. MATERIALS AND METHODS: The endorectal balloon was equipped with an unfoldable radiochromic film. The film was unrolled as the balloon was inflated, and rolled as it was deflated. Its mechanical and imaging properties were tested, and the dosimetric effectiveness was evaluated in clinical photon and proton beams. RESULTS: The size of the endorectal balloon including the film was linearly proportional to the volume of water filled in the balloon, and its position could be identified by X-ray radiography. The loss of dose information due to film cutting was within ±1mm from the cutting line. Applying linear interpolation on cut film, the gamma passing rate was more than 95% for 2%/2mm criteria. The measured dose profiles agreed with the plan within 3% and 4% for the photon and proton beams, respectively. A dose-volume histogram of the anterior rectal wall could be obtained from the measured dose distribution in the balloon, which also agreed well with the plan. CONCLUSIONS: 2D in vivo rectal dosimetry is feasible using the endorectal balloon with a radiochromic film in the radiotherapy of prostate cancer.


Subject(s)
In Vivo Dosimetry/methods , Prostatic Neoplasms/radiotherapy , Radiotherapy Planning, Computer-Assisted/methods , Rectum/diagnostic imaging , Rectum/radiation effects , Film Dosimetry , Humans , Male , Prostatic Neoplasms/pathology , Rectum/pathology
10.
Blood Coagul Fibrinolysis ; 27(5): 594-6, 2016 Jul.
Article in English | MEDLINE | ID: mdl-26829364

ABSTRACT

Identifying a pharmacological means for increasing the production of tissue-type plasminogen activator (t-PA) is always desirable to cure impaired production of this enzyme. An algal fucoidan has been shown to exhibit both novel thrombolytic and synergistic stimulatory effects in a mouse thrombosis model. The plasma levels of active t-PA were measured in mouse arterial thrombus models that were treated with various fucoidans to investigate the mechanism of thrombolysis. The mean plasma level of active t-PA after the infusion of fucoidan was 2.136 ±â€Š0.231 ng/ml for nonthrombolytic Fucus fucoidan and 3.917 ±â€Š0.0.529 ng/ml for thrombolytic Undaria fucoidan, which resulted in a 1.56-2.29-fold increase compared with the healthy control group (1.706 ±â€Š0.194 ng/ml) and the untreated thrombus group (2.506 ±â€Š0.301 ng/ml) (P < 0.01). An algal fucoidan has demonstrated to exert a thrombolytic and stimulatory effect via the induction of t-PA release in a dose-dependent manner in an arterial thrombosis model.


Subject(s)
Fibrinolytic Agents/pharmacology , Phaeophyceae/chemistry , Polysaccharides/pharmacology , Thrombosis/drug therapy , Tissue Plasminogen Activator/biosynthesis , Undaria/chemistry , Animals , Carotid Arteries/drug effects , Carotid Arteries/metabolism , Carotid Arteries/pathology , Disease Models, Animal , Dose-Response Relationship, Drug , Endothelium, Vascular/drug effects , Endothelium, Vascular/metabolism , Endothelium, Vascular/pathology , Fibrinolysis/drug effects , Fibrinolytic Agents/isolation & purification , Mice , Mice, Inbred BALB C , Polysaccharides/isolation & purification , Thrombolytic Therapy , Thrombosis/blood , Thrombosis/pathology , Tissue Plasminogen Activator/metabolism
11.
J Appl Clin Med Phys ; 16(1): 4934, 2014 Jan 08.
Article in English | MEDLINE | ID: mdl-25679149

ABSTRACT

Patient-specific pretreatment verification of intensity-modulated radiation therapy (IMRT) or volumetric-modulated arc therapy (VMAT) is strongly recommended for all patients in order to detect any potential errors in treatment planning process and machine deliverability, and is thus performed routinely in many clinics. Portal dosimetry is an effective method for this purpose because of its prompt setup, easy data acquisition, and high spatial resolution. However, portal dosimetry cannot be applied to IMRT or VMAT with flattening filter-free (FFF) beams because of the high dose-rate saturation effect of the electronic portal imaging device (EPID). In our current report, we suggest a practical QA method of expanding the conventional portal dosimetry to FFF beams with a QA plan generated by the following three steps: 1) replace the FFF beams with flattening filtered (FF) beams of the same nominal energy; 2) reduce the dose rate to avoid the saturation effect of the EPID detector; and 3) adjust the total MU to match the gantry and MLC leaf motions. Two RapidArc plans with 6 and 10 MV FFF beams were selected, and QA plans were created by the aforementioned steps and delivered. The trajectory log files of TrueBeam obtained during the treatment and during the delivery of QA plan were analyzed and compared. The maximum discrepancies in the expected trajectories between the treatment and QA plans were within 0.002 MU for the MU, 0.06° for the motion of gantry rotation, and 0.006 mm for the positions of the MLC leaves, indicating much higher levels of accuracy compared to the mechanical specifications of the machine. For further validation of the method, direct comparisons of the delivered QA FF beam to the treatment FFF beam were performed using film dosimetry and show that gamma passing rates under 2%/2 mm criteria are 99.0%-100% for the all four arc beams. This method can be used on RapidArc plans with FFF beams without any additional procedure or modifications on the conventional portal dosimetry of IMRT and is, therefore, a practical option for routine clinical use.


Subject(s)
Film Dosimetry/instrumentation , Filtration/instrumentation , Particle Accelerators/instrumentation , Quality Assurance, Health Care , Radiotherapy Planning, Computer-Assisted/methods , Radiotherapy, Intensity-Modulated/methods , Humans , Radiotherapy Dosage
12.
Blood Coagul Fibrinolysis ; 23(5): 359-66, 2012 Jul.
Article in English | MEDLINE | ID: mdl-22576287

ABSTRACT

Thrombolytic effects of fucoidans were investigated in the FeCl3-induced arterial thrombus mouse model and compared with heparin and tissue plasminogen activator (t-PA). Thrombosis model was made by applying 5% FeCl3 on the carotid artery of a Balb/c mouse. Twenty minutes after complete occlusion, a couple of test agents including fucoidan were infused into each mouse group with various doses intravenously, before measuring the time to reperfusion. The occluded arteries were reperfused 37.5 ± 12.4 min after administration of unfractionated fucoidan from Undaria pinnatifida sporophylls (UPS-UF) with a dose of 100 mg/kg. In the mice given either a low-molecular-weight UPS fucoidan or fucoidan source from Fucus vesiculosus (FV-UF), reperfusion was delayed at 55.0 ± 8.0 min with a higher reperfusion effective dose (RED) of 1 g/kg or at 63.3 ± 7.2 at RED of 200 mg/kg, respectively. In the control mice given t-PA of 15 mg/kg, reperfusion occurred at 24.8 ± 6.5 min after administration. In contrast, reperfusion was not observed in the occluded mice given heparin (P < 0.001) in the range of 60-1000 mg/kg. Minimal injection of fucoidan in addition to a given t-PA-enabled restoration of blood flow in the blocked artery without reocclusion at 17.2 ± 2.3 min postinjection (P < 0.002). In conclusion, algal fucoidan has both thrombolytic activity and a stimulatory effect on the thrombolytic activity of t-PA in a dose-dependent manner at an arterial thrombosis model.


Subject(s)
Carotid Arteries/drug effects , Coronary Thrombosis/drug therapy , Fibrinolytic Agents/therapeutic use , Polysaccharides/therapeutic use , Tissue Plasminogen Activator/therapeutic use , Animals , Carotid Arteries/physiopathology , Chlorides/pharmacology , Coronary Thrombosis/chemically induced , Coronary Thrombosis/physiopathology , Disease Models, Animal , Dose-Response Relationship, Drug , Drug Synergism , Ferric Compounds/pharmacology , Heparin/therapeutic use , Injections, Intravenous , Mice , Mice, Inbred BALB C , Thrombolytic Therapy/methods , Undaria/chemistry
13.
Phytother Res ; 26(5): 752-7, 2012 May.
Article in English | MEDLINE | ID: mdl-22084059

ABSTRACT

The antithrombotic activities and bleeding effects of selected fucoidans (source from either Undaria pinnatifida sporophylls or from Fucus vesiculosus) have been compared with heparin in the ferric chloride-induced arterial thrombus mouse model. Thrombosis was induced by applying 5% ferric chloride for 3 min on the carotid artery region of Balb/c mouse. Five minutes prior to thrombus induction, mice were infused through the tail vein with either saline (control) or polysaccharides. Either fucoidan or heparin was dosed at 0.1, 1.25, 2.5, 5.0, 10, 25, or 50 mg/kg intravenously (i.v.) The carotid blood flow was monitored until more than 60 min post-thrombus induction. Mouse tail transection bleeding time was measured up to 60 min after making a cut in the mouse tail. Both antithrombotic and bleeding effects were observed in a dose-dependent manner for both fucoidans and heparin. Thrombus formation was totally (reflected by Doppler flow meter) inhibited at either 5 or 50 mg/kg of unfractionated Undaria fucoidan or a low-molecular-weight Undaria fucoidan fraction, respectively, without prolonging the time-to-stop bleeding compared with the control (p < 0.01). The total inhibition of thrombus formation was observed for unfractionated Fucus fucoidan at 25 mg/kg where the time-to-stop bleeding was still significantly prolonged, by as much as 8 ± 1.7 min (p < 0.02). In contrast the heparin-treated group showed total inhibition of thrombus formation even at a small dose of 0.8 mg/kg (400 IU) at which bleeding continued until 60 min. In conclusion algal fucoidans are highly antithrombotic without potential haemorrhagic effects compared with heparin in the arterial thrombus model, but this property differs from algal species to species, and from the molecular structure of fucoidans.


Subject(s)
Anticoagulants/pharmacology , Fibrinolytic Agents/pharmacology , Fucus/chemistry , Polysaccharides/pharmacology , Thrombosis/drug therapy , Undaria/chemistry , Animals , Anticoagulants/isolation & purification , Anticoagulants/therapeutic use , Bleeding Time , Chlorides/pharmacology , Disease Models, Animal , Ferric Compounds/pharmacology , Fibrinolytic Agents/isolation & purification , Fibrinolytic Agents/therapeutic use , Heparin/pharmacology , Injections, Intravenous , Male , Mice , Mice, Inbred BALB C , Polysaccharides/isolation & purification , Polysaccharides/therapeutic use , Thrombosis/chemically induced
14.
J Nanosci Nanotechnol ; 11(1): 511-7, 2011 Jan.
Article in English | MEDLINE | ID: mdl-21446487

ABSTRACT

We studied the effects of seed layers on the structural and optical properties of ZnO nanorods. ZnO and Ag-doped ZnO (ZnO:Ag) seed layers were deposited on glass substrates by magnetron co-sputtering. ZnO nanorods were grown on these seed layers by the chemical bath deposition in an aqueous solution of Zn(NO3)2 and hexamethyltetramine. SEM micrographs clearly reveal that ZnO nanorods were successfully grown on both kinds of seed layers. The XRD patterns indicate that crystallization of ZnO nanorods is along the c-axis. Meanwhile, the packing density and the vertical alignment of the ZnO nanorods on the ZnO seed layer are better than those of the ZnO nanorods on ZnO:Ag. The enhanced growth of nanorods is thought to be due to the fact that the ZnO layer exhibits a higher crystalline quality than the ZnO:Ag layer. According to the low-temperature photoluminescence spectra, the ZnO nanorods on the ZnO seed layer show a narrow strong ultraviolet emission band centered at 369 nm, while those on ZnO:Ag exhibit multiple bands. These results are thought to be related with the crystallinity of ZnO nanorods, the morphologies of ZnO nanorods, and the reflectivities of seed layers. More detailed studies for clarification of the seed layer effect on the growth of ZnO nanorods are desirable.

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