Hydrothermal synthesis of highly luminescent blue-emitting ZnSe(S) quantum dots exhibiting low toxicity.

Myc-induced nuclear antigen (Mina53) is a protein with a molecular weight of 53 kDa expression of which is induced by c-Myc. Increased expression of Mina53 is documented in some human carcinomas. In this study, we found markedly increased Mina53 expression in pancreatic cancer tissue specimens. This expression did not correlate with clinicopathological characteristics, such as sex, age, and presence of distant metastasis. However, there was a statistically significant association with histological differentiation, TNM stage, and lymph node metastases. To study functional role of Mina53, we silenced its expression by siRNA in PANC-1 cells. These cells were arrested in the G2/M phase, and apoptosis rates were increased. In conclusion, increased expression of Mina53 may play an important role in the development of human pancreatic cancer. Mina53 can be used as a marker for pancreatic cancer and may potentially be exploited as a target for treatment of pancreatic cancer.

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Potential Effects of Mina53 on Tumor Growth in Human Pancreatic Cancer

ZnSe nanocrystals have been formed in the silicon dioxide matrix by the sequential high-fluence implantation of Zn+ and Se+ ions at 500 °C. After implantation a part of samples was annealed at 1000 °C for 3 min using rapid thermal annealing. Structural and optical properties of ZnSe/SiO2 nano-composite films were analyzed by means of Rutherford Backscattering Spectrometry, cross-sectional Transmission Electron Microscopy, Raman scattering and photoluminescence techniques. It was shown that a sequence of implantation affects structural and optical properties of synthesized ZnSe clusters. Based on the Raman scattering and photoluminescence data the samples for which Zn ions were implanted first exhibited a better ZnSe crystalline quality than those of reverse sequence of implantation, i.e. with Se ions implanted at the beginning. The bands of blue ZnSe band edge emission and green-red ZnSe deep defect level emission were revealed in the PL spectra of the as-implanted and annealed nano-composites. The PL spectral features observed in the blue region are due to the quantum-size effects in the ZnSe nanocrystals embedded into the silicon dioxide matrix. The PL intensity ratio of the deep defect band to the near edge emission is higher in the samples first implanted with Se ions, and Zn ions implanted next. The effect of rapid thermal annealing on structural and light-emitting properties was discussed.

/pdf/structure-and-optical-properties-of-sio2-films-with-znse-3ix28d5vs5.pdf

Structure and optical properties of SiO2 films with ZnSe nanocrystals formed by ion implantation

Nanocrystalline ZnSe powder and thin film forms have been synthesized via chemical bath deposition technique. The ZnSe thin films are deposited onto ultrasonically clean glass substrates in an aqueous alkaline medium using sodium selenosulphate as Se2− ion source. The ZnSe powder and thin film are characterized by structural, optical and electrical properties. It is confirmed from X-ray diffraction study that cubic phase is present in ZnSe thin film form with (111) as preferred orientation and hexagonal phase is present in ZnSe powder form with (100) as preferred orientation. Optical absorption measurement indicates the existence of direct allowed optical transition with a wide energy gap and blue shift in the fundamental edge has been observed in both cases. The optical band gap of ZnSe powder is greater than the thin film. The electrical conductivity (both dark and photoconductivity) measurements are also carried out in different temperature range and variation in activation energy has been calculated.

https://link.springer.com/content/pdf/10.1007%2Fs10854-017-6552-z.pdf

Study of structural, optical and electrical parameters of ZnSe powder and thin films

We apply first principles density functional and time dependent density functional computational methods to study the structures, densities of states, absorption spectra, and optical gaps of spherical ZnSe and CdTe semiconductor quantum dots in the size range 0.3–2.2 nm. Our calculations are performed in real space without an explicit basis. The surfaces of the quantum dots are passivated with partially charged hydrogen atoms. We find that this passivation technique effectively removes the electronic states associated with the surface atoms from the gaps of ZnSe and CdTe nanocrystals, but does not affect the energies of the quantum-confined electronic states. Our study shows that the absorption gaps of ZnSe and CdTe quantum dots decrease with increasing dot diameter. The size-dependent variations of the computed optical gaps in surface-passivated ZnSe and CdTe quantum dots are found to be consistent with the effects of quantum confinement observed in group IV and group III–V semiconductor nanocrystals.

Ab initio study of ZnSe and CdTe semiconductor quantum dots

Zinc blende, sphericity, monodisperse, high luminescence ZnSe quantum dots (QDs) were synthesized by a one-step mild hydrothermal route with Zn and Se dissolved in aqueous NaOH as the source material. The structure and the morphology of the sample were examined by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The results indicated that the products were cubic blende ZnSe ranging from 3.2 to 4.5 nm in size. TEM images showed that the QDs have very good dispersibility and distribution. The characteristic features of the absorption and photoluminescence spectra of ZnSe quantum dots were studied at room temperature. Compared with the bulk ZnSe, the absorption edges and luminescent peaks of ZnSe QDs were blue shifted to higher energies due to the quantum confinement effect. Photoluminescence at ultraviolet excitation showed the strong emission at 390 nm related to the higher excitonic states. ZnSe QDs exhibiting photoluminescence line widths as narrow as 40-60 nm. Meanwhile, we simply explored the theoretical mechanism of luminescence in ZnSe QDs and analogized the relation of various point defect concentrations of ZnSe.

Yu Hua Wang

Papers

Ultraviolet-blue photoluminescence of ZnSe quantum dots.