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391.
Cooperative and FRET‐Assisted Brightness Enhancement in Oligo(phenylene ethynylene): Quantum Dot Organic–Inorganic Nanohybrids
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Dr. Arun Gopi Manikantan Sajitha Reethu Haridas Listo Varghese Dr. Karuvath Yoosaf 《化学:亚洲杂志》2018,13(11):1492-1499
Herein, we combine the ideas of concerted emission from fluorophore ensembles and its further amplification through FRET in an organic–inorganic hybrid approach. Spherical and highly fluorescent organic nanoparticles (FONPs, Φf=0.38), prepared by the self‐assembly of oligo(phenylene ethynylene) (OPE) molecules, were selected as a potential donor material. This organic core was then decorated with a shell of fluorescent CdSe/ZnS core–shell quantum dots (QDs; <d>?5.5 nm, Φf=0.27) with the aid of a bifunctional ligand, mercaptopropionic acid. Its high extinction coefficient (?≈4.1×105 m ?1 cm?1) and good spectral match with the emission of the FONPs (J(λ)≈4.08×1016 m ?1 cm?1 nm4) made them a better acceptor candidate to constitute an efficient FRET pair (ΦFRET=0.8). As a result, the QD fluorescence intensity was enhanced by more than twofold. The fundamental calculations carried out indicated an improvement in all the FRET parameters as the number of QDs around the FONPs was increased. This, together with the localization of multiple QDs in a nanometric dimension (volume≈1.8×106 nm3), gave highly bright reddish luminescent hybrid particles as visualized under a fluorescence microscope. 相似文献
392.
The synthesis and development of sodium (Na)-substituted hydroxyapatite (HAp)/chitosan (CS) composite using poly (O-phenylenediamine) (PoPD) coating on 316L SS substrate for improving bioactivity and corrosion protection was studied. The surface of Na-HAp/CS/PoPD bilayer coatings on 316L SS substrate was characterized by diverse analytical techniques. The open circuit potential (OCP) measurement, potentiodynamic polarization, and impedance test revealed that the bilayer coating provides excellent protection to the substrate against the corrosion in the simulated body fluid (SBF) solution. This interior layer of the coating acts as a barrier against the release of metal ions from the substrate, which was confirmed by inductively coupled plasma-atomic emission spectroscopy. Besides, the mechanical properties of the coatings were analyzed. From the obtained results, the bilayer coating exhibited greater mechanical strength than the individual coating. An in vitro bioactivity of the coatings was assessed by immersion in the SBF solution at 7–28 days. The apatite formation of bilayer coatings on 316L SS substrate is found to be more bioactive compared with the Na-HAp, PoPD, and Na-HAp/CS. The in vitro biocompatibility test showed no adverse effects, which was proved by the enhanced biocompatibility of the bilayer coating on 316L SS. 相似文献
393.
Peptide-based probes play prominent roles in biomedical research due to their promising properties such as high biocompatibility, fast excretion, favorable pharmacokinetics as well as easy and robust preparation. Considering the translation of imaging probes into clinical applications, peptide-based probes remain to be the most desirable and optimal candidates. 相似文献
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396.
针对基于马赫-曾德干涉仪结构的硅基光调制器中非线性电光响应的问题,采用包含PN结非线性调制损耗和非线性折射率变化的模型,通过数值仿真方法,研究了上下两臂对称和不对称两种情况下,调制损耗对硅基光调制器非线性的影响.对比考虑调制损耗和忽略调制损耗的模型,发现在常规大信号情况下,当光调制器偏置相位为0时,调制损耗使得三次谐波增强,四次谐波减弱;当光调制器偏置相位为π/2时,调制损耗使得二次和四次谐波增强;而在小信号情况下,三次和四次等高次谐波不明显,在光调制器偏置相位为0时,调制损耗在光调制器上下两臂不对称情况下增加了基频分量串扰;在光调制器偏置相位为π/2时,调制损耗的影响主要表现为增加了二次谐波分量. 相似文献
397.
Monodispersed cobalt nanoparticles (NPs) with controllable size (8–14 nm) have been synthesized using thermal decomposition of dicobaltoctacarbonyl in organic solvent. The as-synthesized high magnetic moment (125 emu/g) Co NPs are dispersible in various organic solvents, and can be easily transferred into aqueous phase by surface modification using phospholipids. However, the modified hydrophilic Co NPs are not stable as they are quickly oxidized, agglomerated in buffer. Co NPs are stabilized by coating the MFe2O4 (M=Fe, Mn) ferrite shell. Core/shell structured bimagnetic Co/MFe2O4 nanocomposites are prepared with tunable shell thickness (1–5 nm). The Co/MFe2O4 nanocomposites retain the high magnetic moment density from the Co core, while gaining chemical and magnetic stability from the ferrite shell. Compared to Co NPs, the nanocomposites show much enhanced stability in buffer solution at elevated temperatures, making them promising for biomedical applications. 相似文献
398.
Yamamoto YS Oshima Y Shinzawa H Katagiri T Matsuura Y Ozaki Y Sato H 《Analytica chimica acta》2008,619(1):8-13
A ball lens hollow-fiber Raman probe (BHRP) is a powerful tool for in vivo nondestructive subsurface analysis of biomedical tissues in a living body. It has confocal-like optical properties, but its collection volume is rather large in comparison with that of a conventional confocal Raman system. Therefore, the obtained Raman spectra have contributions from the upper and lower layers at different rates depending on the thickness of the upper layer when the measurement point is close to the boundary surface of the two layers. In the present study, we describe a methodology to extract quantitative information about the thickness of the subsurface layer structure by using a BHRP combined with the partial least-square regression (PLSR) analysis. The simulation study indicates that distribution of the collection efficiency in the collection volume of the BHRP is similar to a Gaussian distribution. The empirical study suggests that the PLSR model built with only a principal component (PC) 1 based on the linearized depth data gives good prediction. 相似文献
399.
The objective of this contribution is to review the application of advanced multivariate data-analysis techniques in the field
of mid-infrared (MIR) spectroscopic biomedical diagnosis. MIR spectroscopy is a powerful chemical analysis tool for detecting
biomedically relevant constituents such as DNA/RNA, proteins, carbohydrates, lipids, etc., and even diseases or disease progression
that may induce changes in the chemical composition or structure of biological systems including cells, tissues, and bio-fluids.
However, MIR spectra of multiple constituents are usually characterized by strongly overlapping spectral features reflecting
the complexity of biological samples. Consequently, MIR spectra of biological samples are frequently difficult to interpret
by simple data-analysis techniques. Hence, with increasing complexity of the sample matrix more sophisticated mathematical
and statistical data analysis routines are required for deconvoluting spectroscopic data and for providing useful results
from information-rich spectroscopic signals. A large body of work relates to the combination of multivariate data-analysis
techniques with MIR spectroscopy, and has been applied by a variety of research groups to biomedically relevant areas such
as cancer detection and analysis, artery diseases, biomarkers, and other pathologies. The reported results indeed reveal a
promising perspective for more widespread application of multivariate data analysis in assisting MIR spectroscopy as a screening
or diagnostic tool in biomedical research and clinical studies. While the authors do not mean to ignore any relevant contributions
to biomedical analysis across the entire electromagnetic spectrum, they confine the discussion in this contribution to the
mid-infrared spectral range as a potentially very useful, yet underutilized frequency region. Selected representative examples
without claiming completeness will demonstrate a range of biomedical diagnostic applications with particular emphasis on the
advantageous interaction between multivariate data analysis and MIR spectroscopy. 相似文献
400.
硅基光子技术的发展为新型微纳光学功能器件和片上系统提供了高可靠、高精度的实现手段.采用硅基光子技术构建的具有连续(准连续)模式微腔与离散模式的微腔耦合产生的Fano共振现象得到了广泛关注.Fano共振光谱在共振波长附近具有不对称且尖锐的谐振峰,传输光的强度在共振波长附近从0突变为1,该机制可显著提高硅基光开关、探测器、传感器,以及光非互易性全光信号处理的性能.本综述分析了Fano共振的一般数学表述,总结了当前硅基光子微腔耦合产生Fano共振的理论模型研究现状,讨论了不同类型硅光器件实现Fano共振的方法,比较各种方案优劣及适用场合,梳理了Fano共振在全光信号处理方面的应用研究情况.最后探讨存在的一些问题及未来可能的相关研究方向. 相似文献