Biological Toxicities and Aggregation Effects of ʟ-Glycine and ʟ-Alanine Capped ZnS:Mn Nanocrystals in Aqueous Solution

Park, Sanghyun,Song, Byungkwan,Kong, Hoon Young,Byun, Jonghoe,Hwang, Cheong-Soo Korean Chemical Society 2014 Bulletin of the Korean Chemical Society Vol.35 No.4

In this study, water-dispersible ZnS:Mn nanocrystals were synthesized by capping the surface with conventional and simple structured amino acid ligands: $\small{L}$-Glycine and $\small{L}$-Alanine. The ZnS:Mn-Gly and ZnS:Mn-Ala nanocrystal powders were characterized by XRD, HR-TEM, EDXS, ICP-AES, and FT-IR spectroscopy. The optical properties were measured by UV-Visible and photoluminescence (PL) spectroscopy. The PL spectra for the ZnS:Mn-Gly and ZnS:Mn-Ala showed broad emission peaks at 599 nm and 607 nm with PL efficiencies of 6.5% and 7.8%, respectively. The measured average particle size from the HR-TEM images were $6.4{\pm}0.8$ nm (ZnS:Mn-Gly) and $4.1{\pm}0.5$ nm (ZnS:Mn-Ala), which were also supported by Debye-Scherrer calculations. In addition, the degree of aggregation of the nanocrystals in aqueous solutions were measured by a hydrodynamic light scattering method, which showed formation of sub-micrometer size aggregates for both ZnS:Mn-Gly ($273{\pm}94$ nm) and ZnS:Mn-Ala ($233{\pm}34$ nm) in water due to the intermolecular attraction between the capping amino acids molecules. Finally, the cytotoxic effects of ZnS:Mn-Gly and ZnS:Mn-Ala nanocrsystals over the growth of wild type E. coli were investigated. As a result, no toxicity was shown for the ZnS:Mn-Gly nanocrystal in the colloidal concentration region from 1 ${\mu}g/mL$ to 1000 ${\mu}g/mL$, while ZnS:Mn-Ala showed significant toxicity at 100 ${\mu}g/mL$.

White Light Emission from a Colloidal Mixture Containing ZnS Based Nanocrystals: ZnS, ZnS:Cu and ZnS:Mn

Lee, Jae Woog,Hwang, Cheong-Soo Korean Chemical Society 2014 Bulletin of the Korean Chemical Society Vol.35 No.1

Water dispersible ZnS based nanocrystals: ZnS (blue), ZnS:Cu (green) and ZnS:Mn (yellow-orange) were synthesized by capping the surface of the nanocrystals with a mercaptopropionic acid (MPA) molecule. The MPA capped ZnS based nanocrystal powders were characterized by using XRD, HR-TEM, EDXS, FT-IR, and FT-Raman spectroscopy. The optical properties of the colloidal nanocrystals were also measured by UV/Vis and photoluminescence (PL) spectroscopies in aqueous solvents. The PL spectra showed broad emission peaks at 440 nm (ZnS), 510 nm (ZnS:Cu) and 600 nm (ZnS:Mn), with relative PL efficiencies in the range of 4.38% to 7.20% compared to a reference organic dye. The measured average particle sizes from the HR-TEM images were in the range of 4.5 to 5.0 nm. White light emission was obtained by mixing these three nanocrystals at a molar ratio of 20 (ZnS):1 (ZnS:Cu):2 (ZnS:Mn) in water. The measured color coordinate of the white light was (0.31, 0.34) in the CIE chromaticity diagram, and the color temperature was 5527 K.

SYNTHESIS AND PHOTOLUMINESCENCE OF WATER-SOLUBLE ZnS:Mn^(2+)/ZnS QUANTUM DOTS BY NUCLEATION DOPING STRATEGY

ZHANGSEN YU,XIYING MA 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2011 NANO Vol.6 No.1

We report the synthesis of luminescent-doped core/shell quantum dots (QDs) of water-soluble manganese-doped zinc sulfide (ZnS:Mn^(2+)/ZnS). QDs of ZnS:Mn^(2+)/ZnS were prepared by nucleation doping strategy, with thioglycolic acid (TGA) as stabilizer in aqueous solution. Structure and optical properties of the ZnS:Mn^(2+)/ZnS core/shell quantum dots were characterized by X-ray diffraction and photoluminescence emission spectroscopy. The influence of the synthesis conditions on the luminescent properties of ZnS:Mn^(2+)/ZnS QDs is discussed. Different Mn^(2+) concentrations, ratios of the TGA/(Zn+Mn) and thickness of the ZnS shell were used. Results showed that the ZnS:Mn^(2+)/ZnS QDs are water-soluble and have improved fluorescence properties. Therefore, Mn^(2+)-doped ZnS quantum dots could be potential candidates as fluorescent labeling agents in biology.

Er 첨가에 따른 백색 LED용 ZnS:Mn 황색 형광체의 발광특성

유일 ( Ll Yu ) 한국화상학회 2010 한국화상학회지 Vol.16 No.3

Er을 첨가한 ZnS:Mn 형광체를 1000℃에서 4시간 고상반응법으로 소결하여 제조하였다. 결정 구조 및 광 특성은 XRD, PL 그리고 SEM을 통하여 분석하였다. XRD 결과, ZnS:Mn 형광체는 hexagonal구조가 나타났고, Er의 농도가 증가함에 따라 Er(2)O(3) 구조가 관찰되었다. ZnS:Mn 형광체의 평균입자 크기는 약 15 ㎛였고, Er 첨가와 함께 ZnS:Mn,Er 형광체의 입자 크기는 감소하였다. 580 nm 발광 피크는 ZnS:Mn,Er 형광체에서 Mn(2+) 이온의 (4)T(1)→(6)A(1)으로의 전이에 의한 것이다. Er을 0.5 mol% 첨가한 형광체의 발광 세기는 Er을 첨가하지 않은 ZnS:Mn 형광체보다 높았다. ZnS:Mn,Er 형광체에서 발광 세기의 증가는 Er(3+)에서 Mn(2+)로의 에너지 전이에 의한 것으로 생각된다. Er co-doped ZnS:Mn phosphors were prepared by solid state reaction method in air at 1000 ℃ for 4h. The optical properties and structures of ZnS:Mn,Er phosphors were investigated by X-ray diffraction, Photoluminescence and Scanning Electro Microscopy. ZnS:Mn phosphors showed XRD patterns of hexagonal structure, and Er(2)O(3) structure in ZnS:Mn Er with increasing concentration of Er were observed from XRD. The particle size of Er non-doped ZnS:Mn phosphors was about 15 μm and particle size of the phosphors decreased with doping Er. The luminescence of 580 nm in ZnS:Mn,Er phosphors was associated with (4)T(1)→(6)A(1) transition of Mn(2+) ions. Photoluminescence intensity of ZnS:Mn doped with Er 0.5 mol% was definitely higher than that of Er non-doped sample. The enhanced photoluminescent intensity in the ZnS:Mn,Er phosphors was interpreted by energy transfer from Er(3+) to Mn(2+).

Preparation and characterization of ZnS based nano-crystalline particles for polymer light-emitting diodes

Hwang, Jeong-mi,Oh, Mi-Ok,Kim, Il,Lee, Jin-Kook,Ha, Chang-Sik Elsevier 2005 Current Applied Physics Vol.5 No.1

<P><B>Abstract</B></P><P>Nano-crystalline ZnS:Mn and its derivatives are promising as a novel luminescent center because of its high quantum efficiency at room temperature. In this work, three different kinds of ZnS based nano-crystalline particles were synthesized and characterized in order to be utilized for polymer light-emitting diodes; ZnS:Mn, ZnS:CuCl, and ZnS:AgCl. Some of the ZnS based nanocrystals were either hybridized with poly(acrylic acid)(PAA) or doped to poly(9-vinyl carbazole)(PVCz)). The XRD analysis showed that the diameter of the ZnS based particles was in the range of 11.8–23.4 nm. In all the ZnS based nanocrystals hybridized with PAA, the photoluminescence (PL) was enhanced in comparison to the ZnS:Mn regardless of the metal ion. It was found that the ZnS:AgCl hybridized with PAA showed the highest PL and the ZnS:CuCl hybridized with PAA showed the lowest PL among the three ZnS based nanocrystals hybridized with PAA. The PL of PVCz doped with the ZnS based nanocrystals, however, was lower in comparison to the ZnS:Mn regardless of the metal ion though the differences were not large.</P>

White Light Emission from a Colloidal Mixture Containing ZnS Based Nanocrystals: ZnS, ZnS:Cu and ZnS:Mn

Jae-Woog Lee,Cheong-Soo Hwang 대한화학회 2014 Bulletin of the Korean Chemical Society Vol.35 No.1

Water dispersible ZnS based nanocrystals: ZnS (blue), ZnS:Cu (green) and ZnS:Mn (yellow-orange) were synthesized by capping the surface of the nanocrystals with a mercaptopropionic acid (MPA) molecule. The MPA capped ZnS based nanocrystal powders were characterized by using XRD, HR-TEM, EDXS, FT-IR, and FT-Raman spectroscopy. The optical properties of the colloidal nanocrystals were also measured by UV/Vis and photoluminescence (PL) spectroscopies in aqueous solvents. The PL spectra showed broad emission peaks at 440 nm (ZnS), 510 nm (ZnS:Cu) and 600 nm (ZnS:Mn), with relative PL efficiencies in the range of 4.38% to 7.20% compared to a reference organic dye. The measured average particle sizes from the HR-TEM images were in the range of 4.5 to 5.0 nm. White light emission was obtained by mixing these three nanocrystals at a molar ratio of 20 (ZnS):1 (ZnS:Cu):2 (ZnS:Mn) in water. The measured color coordinate of the white light was (0.31, 0.34) in the CIE chromaticity diagram, and the color temperature was 5527 K.

Biological Toxicities and Aggregation Effects of L-Glycine and L-Alanine Capped ZnS:Mn Nanocrystals in Aqueous Solution

Sanghyun Park,Byungkwan Song,Hoon Young Kong,Jonghoe Byun,Cheong-Soo Hwang 대한화학회 2014 Bulletin of the Korean Chemical Society Vol.35 No.4

In this study, water-dispersible ZnS:Mn nanocrystals were synthesized by capping the surface with conventional and simple structured amino acid ligands: L-Glycine and L-Alanine. The ZnS:Mn-Gly and ZnS:Mn-Ala nanocrystal powders were characterized by XRD, HR-TEM, EDXS, ICP-AES, and FT-IR spectroscopy. The optical properties were measured by UV-Visible and photoluminescence (PL) spectroscopy. The PL spectra for the ZnS:Mn-Gly and ZnS:Mn-Ala showed broad emission peaks at 599 nm and 607 nm with PL efficiencies of 6.5% and 7.8%, respectively. The measured average particle size from the HR-TEM images were 6.4 ± 0.8 nm (ZnS:Mn-Gly) and 4.1 ± 0.5 nm (ZnS:Mn-Ala), which were also supported by Debye-Scherrer calculations. In addition, the degree of aggregation of the nanocrystals in aqueous solutions were measured by a hydrodynamic light scattering method, which showed formation of sub-micrometer size aggregates for both ZnS:Mn-Gly (273 ± 94 nm) and ZnS:Mn-Ala (233 ± 34 nm) in water due to the intermolecular attraction between the capping amino acids molecules. Finally, the cytotoxic effects of ZnS:Mn-Gly and ZnS:Mn-Ala nanocrsystals over the growth of wild type E. coli were investigated. As a result, no toxicity was shown for the ZnS:Mn-Gly nanocrystal in the colloidal concentration region from 1 μg/mL to 1000 μg/mL, while ZnS:Mn- Ala showed significant toxicity at 100 μg/mL.

Al2O3 기판위에 Ge/ZnS 다층박막을 이용한 적외선 대역 투과필터의 제작 및 특성연구

박문찬,김대종,고견채 대한시과학회 2012 대한시과학회지 Vol.14 No.3

목적: Al2O3 기판위에 Ge/ZnS 다층박막을 이용하여 중심파장 3450nm에서 반치폭이 약 150nm이고 투과율이 약 95%인 중 적외선 투과필터를 제작하고, 이 필터의 박막 특성을 연구하였다. 방법: 설계에 있어 기판의 한 면은 장파장 투과 필터로,다른 면은 단파장 투과 필터로 코팅한 후 한개의 기판을 중심으로 전면에는 장파장 투과 필터를 후면에는 단파장 투과 필터를 합성하여 중적외선 대역투과 필터를 설계하였다.또한 전자빔 증착장비를 이용하여Ge/ZnS 다층박막 중적외선 대역 투과 필터를 제작한 후, FTIR을 이용하여 투과율을 측정하였고, XRD 데이타로부터 박막의 구조를 분석하였으며, XPS분석으로부터 박막 성분을 확인하였다. 결과: 장파장 투과 필터는 기준파장 2700nm에서 [air/0.490H 0.904L 0.952H 1.086L 1.747H 0.489L (HL)9 H 0.350L 1.616H/Al2O3 substrate]와 같이 설계되었으며, 이때 고굴절률(H)과 저굴절률(L) 물질은 각각 Ge과 ZnS이였다. 또한 단파장 투과필터는 기준파장 4200nm에서 [air/1.261H (LH)7 0.921L 1.306H/Al2O3 substrate]와 같이 설계되었으며, 고굴절률 물질과 저굴절률 물질은 장파장 투과필터와 동일하였다. 설계를 바탕으로 제작한 적외선 투과 필터의 최대파장피크가 제작조건의 변화에 의거하여 이론치에 비해 약 30nm 오른쪽 이동되어 있는 것을 확인하였다. 제작된 필터의 ZnS층이 cubic (111) 결정구조를 가지고 있는 것을 XRD분석으로 확인하였으며, XPS분석에 의해 Ge층이 맨 위층이며 ZnS층과 교번인 다층막으로 형성돼 있다는 것을 확인할 수 있었다. 결론: Al2O3 기판위에 Ge와 ZnS를 교번으로, 한 면은 27층의 장파장 투과필터로 구성되고, 다른 면은 17층의 단파장 투과 필터의 다층박막을 제작하여, 3450nm 중심파장에서 150nm 반치폭을 갖으며 투과율은 약 95%인 중적외선 대역 투과 필터를 제작하였다. Purpose: The mid-infrared bandpass filters with a 3450nm central wavelength of 95% transmittance and 150nm FWHM using Ge/ZnS mutilayer were fabricated on Al2O3 substrate, and their characteristics were studied. Method: In design of the mid-infrared bandpass filters, one surface and the other surface on Al2O3 substrate was composed of longwave-pass filter, and shortwave-pass filter, respectively. IR filters were made by electron beam evaporation apparatus and the transmittaces of the filters were measured by FTIR. The structures of IR filters were assessed by XRD patterns and the compositions of filters were analysed with XPS. Results: The optimization for the longwave-pass filter at reference wavelength of 2700nm was [air/0.490H 0.904L 0.952H 1.086L 1.747H 0.489L (HL)9 H 0.350L 1.616H/Al2O3 substrate], in which the high and low refractive materials are Ge and ZnS, respectively. The optimization for the short-pass filter at reference wavelength of 4200nm was [air/1.261H (LH)7 0.921L 1.306H/Al2O3 substrate], in which the high and low refractive material are the same as the materials of longwave-pass filter. IR filters were fabricated on the basis of simulation data, of which the peak of the maximun transmittance was shifted to the right of about 30nm wavelength when compared with simulation data. It was known that ZnS thin film has a cubic structure with a (111) crystal surface and the structure of Ge thin film was amorphous from XRD patterns of the filter, and Ge layer was deposited on top of Ge/ZnS mutilayer and the filter was consisted of alternating layers of Ge and ZnS layer from XPS analysis of IR filters. Conclusions: One surface and the other surface of IR filter using alterating layer of Ge and ZnS were designed for longwave-pass filter, and shortwave-pass filter, respectively. The infrared bandpass filters with a 3450nm central wavelength of 95% transmittance and 150nm FWHM were fabricated on Al2O3 substrate.

Mn-doped ZnS 결정의 광학적 특성

방태환,최성휴 한국물리학회 2013 새물리 Vol.63 No.9

ZnS:Mn crystals have a hexagonal structure based on the X-ray diffraction analysis. The lattice constants were a = 3.822 °A and c = 6.256 °A for the ZnS:Mn crystal. The optical absorption spectrum near the fundamental absorption edge showed that this crystal has a direct energy band gap. The direct and the indirect energy band gaps are given by Egd = 3.488 eV and Egi = 3.133 eV at 300 K, respectively. The photoluminescence spectrum of the ZnS:Mn crystal was measured in the wavelength range of 300 nm 850 nm at 300 K, and a high intensity emission peak due to the Mn2+ ion was observed near 583.6 nm. This PL peak was attributed to a radiative transition between the split electron energy levels of the Mn2+ ion occupying the Td symmetry site of the ZnS:Mn crystal host lattice.. ZnS:Mn 결정을 성장하여 성장된 결정의 구조와 격자상수 및 광학적에너지 간격 그리고 광발광 특성을 조사하였다. 성장된 결정은 hexagonal 구조이며 ZnS:Mn 격자상수를 구하면 a = 3.822 °A 이었다. 이 결정의 광흡수 spectrum은 측정시료의 온도를 300K로 유지하고, 300 $\sim$ 900 nm 파장영역에서 측정하였다. 기초 흡수단영역인 355 nm에서 급격한 광흡수가 나타났으며 측정된 광흡수스펙트럼으로부터 계산한 ZnS:Mn 결정의 직접전이 에너지 간격은 Egd = 3.488 eV , 간접전이 에너지 간격 Egi = 3.133 eV이었다. 광발광 특성 스펙트럼으로부터 443.1 nm 영역에서 ZnS 결정에 의한광발광 피크, 그리고 583.6 nm 영역에서 Mn을 첨가한 ZnS:Mn 결정에 의한광발광 피크가 나타났다. 583.6 nm 광발광 peak는 ZnS:Mn 결정에서zinc와 치환된 Mn이 Td symmetry site에 Mn2+ 이온으로 위치하고분리된 Mn2+ 이온의 에너지 준위사이의 radiative transition에기인한 peak다.

다양한 온도 조건에서의 ZnS:Mn/ZnS 코어-쉘 양자점의 합성 및 광 특성에 관한 연구

이재욱,황청수,Lee, Jae-Woog,Hwang, Cheong-Soo 대한화학회 2009 대한화학회지 Vol.53 No.6

본 논문에서는 ZnS:Mn/ZnS 코어-쉘 양자점을 유기금속전구체의 열분해 방법으로 합성하였다. 쉘의 형성온도를 135$^{\circ}C$로 고정한 반면 코어 나노입자의 합성 온도 조건을 다양화 하여 각 조건하에서 형성된 양자점들의 특성을 조사하였다. 실험을 통해 얻은 양자점들은 UV-Vis, 액체 photoluminescence (PL) spectroscopy 방법으로 광 특성을 조사하였으며, 또한 XRD, HR-TEM, 및 EDXS 분석으로 입자크기와 조성 등을 측정하였다. 실험 결과 가장 좋은 광 특성을 보인 나노입자의 합성조건은 코어와 쉘 모두 135$^{\circ}C$인 것으로 밝혀 졌으며, 이 조건에서 얻은 양자점은 583 nm 의 PL 발광 피이크와 42.15%의 높은 양자효율을 나타내었다. HR-TEM 으로 측정한 ZnS:Mn/ZnS 양자점의 평균 입자크기는 지름이 약 4.0 - 5.4 nm 정도였으며, 특히 150$^{\circ}C$의 온도 조건에서는 타원형의 입자가 형성되는 것이 관찰되었다. ZnS:Mn/ZnS core-shell quantum dots (QDs), were synthesized via a thermal decomposition reaction of organometallic precursors in a hot solvent mixture. The synthetic conditions of the quantum dots were monitored at various reaction temperatures for the core formation, while the shell formation temperature was fixed at 135$^{\circ}C$. The obtained colloidal nanocrystals at corresponding temperatures were characterized by UV-Vis, solution photoluminescence (PL) spectroscopies, and further obtained powders were characterized by XRD, HR-TEM, and EDXS analyses. The synthetic temperature condition to obtain the best PL emission intensity for the core-shell QD was 135$^{\circ}C$, for both core and shell formation. At this temperature, solution PL spectrum showed a narrow emission peak at 583 nm with a relative PL quantum efficiency of 42.15%. In addition, the measured spherical particle sizes for the ZnS:Mn/ZnS nanocrystals via HR-TEM were in the range of 4.0 to 5.4 nm, while ellipsoidal particles were obtained at 150$^{\circ}C$.