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91.
Metalloprotein tethered CdSe nanoparticles have been generated to provide selective and reagentless maltose biosensing. As opposed to cell or protein detection by semiconducting nanoparticle bioconjugates, a modular method for small-molecule detection using semiconducting nanoparticle bioconjugates has been difficult. Here we report a method for reagentless protein-based semiconducting nanoparticle biosensors. This method uses Ru(II) complex-CdSe nanoparticle interactions and the maltose-induced conformation changes of maltose binding protein to alter the CdSe nanoparticle fluorescence emission intensity. In this proof-of-principle system, the maltose-induced protein conformation changes alter the Ru(II) complex-CdSe nanoparticle interaction, which increases the CdSe emission intensity. Altered CdSe emission intensity effects are best described as electron transfer from the Ru(II) complex to the CdSe excited state forming the nonfluorescent CdSe anion. Four surface-cysteine, Ru(II) complex-attached maltose-binding proteins have been studied for maltose dependent alteration of CdSe emission intensities. With 3.0-3.5 nm diameter CdSe nanoparticles, all ruthenated maltose-binding proteins display similar maltose-dependent increases (1.4-fold) in CdSe emission intensity and maltose binding affinities (KA = 3 x 106 M-1). For these four systems, the only difference was the sample-to-sample variation in maltose-dependent responses. Thus, very few surface cysteine mutations need to be examined to find a successful biosensor, as opposed to analogous systems using organic fluorophores. This strategy generates a unimolecular, or reagentless, semiconducting nanoparticle biosensor for maltose, which could be applied to other proteins with ligand-dependent conformation changes. 相似文献
92.
Jonathan Rosenhead 《The Journal of the Operational Research Society》1978,29(2):105-111
A case study is presented of the application of robustness analysis to the choice of examination subjects to be made by a 14-year-old girl. The analysis is conducted in terms of the desirable future career options which may be preserved by different combinations of subjects, and also of the balance with topics selected for their intrinsic interest. The approach, which employs very limited technical apparatus, is justified on a number of grounds-in particular, the crucial importance of uncertainty, and the need for understanding and acceptance by a "client" very unlike the corporate manager. Some tentative conclusions are reached on the extension of such methods to other cases of decision-makers with little, if any, resources to control except their own lives. 相似文献
93.
T. Bernard Tate 《The Journal of the Operational Research Society》1977,28(4):765-779
Good technique, i.e. competence in carrying out operational research, is as vital for the practitioner to acquire as competence in the traditional ‘techniques’. It is suggested that universities should teach students how to conduct simple projects prior to alerting them to more sophisticated methodological issues.As an aid to this task, the traditional five or six parts of an operational research project are broken down and extended into 39 steps, and regrouped into three phases. Also, five skills are identified as being conceptually essential to "good" operational research, which students can develop through tackling suitable case studies. 相似文献
94.
The adsorptive stripping voltammetric determination of germanium(IV) based on the adsorptive accumulation of the germanium(IV)-pyrogallol complex on a hanging mercury drop electrode is reported. The reduction current of the adsorbed germanium complex is measured by differential-pulse cathodic stripping voltammetry. The peak potential is at -0.42 V vs. Ag AgCl (saturated KCL). The effects of various parameters (ligand concentration, supporting electrolytic composition and concentration, accumulation potential and collection time) on the response are discussed. With controlled accumulation for 3 min, the detection limit is 1.2 x 10(-9) M germanium. The relative standard deviation (at 1.2 x 10(-8) M germanium) is 3.6%. Possible interferences are evaluated. The applicability of the method to the determination of germanium(IV) in ore samples was also successfully carried out. 相似文献
95.
Qing-de Chen Xing-hai Shen 《高分子科学》2005,(6):635-642
In the UV-Vis spectra of pure light-scattering systems, there is an exponential relationship between absorbance and wavelength (A = Kλ^-n). Here, the exponent n is named as flocculation-coagulation parameter. In the present paper, the effects of different additives on the stability of poly(N,N'-methylenebisacrylamide-co-4-vinylpyridine) (poly(Bis-co-4-VP)) microgel dispersion were studied in detail via this parameter. The results showed that the stability of the dispersion mainly comes from the ionization of pyridine groups, making the microgel positively charged on its surface. This was confirmed by the measurement of Zeta potential and the result of conductometric titration. The result of fluorescence analysis indicated that the hydrophobicity in the microgels is enhanced with the increase in total 4-VP unit content. 相似文献
96.
Zi-Shu Yang Yuhang Yao Adam C. Sedgwick Cuicui Li Ye Xia Yan Wang Lei Kang Hongmei Su Bing-Wu Wang Song Gao Jonathan L. Sessler Jun-Long Zhang 《Chemical science》2020,11(31):8204
We report here porphodilactol derivatives and their corresponding metal complexes. These systems show promise as “all-in-one” phototheranostics and are predicated on a design strategy that involves controlling the relationship between intersystem crossing (ISC) and photothermal conversion efficiency following photoexcitation. The requisite balance was achieved by tuning the aromaticity of these porphyrinoid derivatives and forming complexes with one of two lanthanide cations, namely Gd3+ and Lu3+. The net result led to a metalloporphodilactol system, Gd-trans-2, with seemingly optimal ISC efficiency, photothermal conversion efficiency and fluorescence properties, as well as good chemical stability. Encapsulation of Gd-trans-2 within mesoporous silica nanoparticles (MSN) allowed its evaluation for tumour diagnosis and therapy. It was found to be effective as an “all-in-one” phototheranostic that allowed for NIR fluorescence/photoacoustic dual-modal imaging while providing an excellent combined PTT/PDT therapeutic efficacy in vitro and in vivo in 4T1-tumour-bearing mice.We report here porphodilactol derivatives and their corresponding metal complexes as “all-in-one” phototheranostics by controlling the relationship between intersystem crossing (ISC) and photothermal conversion efficiency following photoexcitation. 相似文献
97.
A novel method for the determination of proteins in aqueous solutions has been developed based on the enhancement of resonance light scattering (RLS) of Ag nanoparticles in the presence of proteins. Factors including acidity of the media, concentration of Ag hydrosol, reaction time, temperature, and interference of non-protein substances were investigated. Under the optimal conditions, with the enhanced RLS signals at 452nm, the linear ranges of calibration curves were 0–0.8µgmL–1 for bovine serum albumin (BSA), 0–1.2µgmL–1 for human serum albumin (HSA), and 0–2.5µgmL–1 for human -IgG (-IgG), respectively. The detection limits were 1.3ngmL–1 for BSA, 10ngmL–1 for HAS, and 5.7ngmL–1 for -IgG.This method has been applied to the analysis of synthetic samples and real human serum samples, and the results were in good agreement with those reported by the hospital, indicating that the method presented here is not only sensitive and simple, but also reliable and suitable for practical applications. 相似文献
98.
99.
氯化血红素催化新型荧光反应测定葡萄糖的研究 总被引:3,自引:0,他引:3
本文用流动注射分析了研究了过氧化物模拟酶催化过氧新型荧光底物(N,N-二氰甲基邻苯二胺,DCMOPA)的最优条件。结果表明,该系统可用于定量测定氧化氢及催化氯化血红素的浓度。 相似文献
100.
Haiwen Zhang David W. Norman Tracey M. Wentzell Alison M. Irving Janet P. Edwards Susan L. Wheaton Christopher M. Vogels Stephen A. Westcott Felix J. Baerlocher Andreas Decken 《Transition Metal Chemistry》2005,30(1):63-68
Reactions of salicylaldehydes with boronate ester derivatives of aniline have been examined. Addition of these Schiff base ligands to palladium acetate or Na2PdCl4 afforded novel boron-containing trans-bis(N-arylsalicylaldiminato) palladium complexes.Condensation of salicylaldehyde (2-HOC6H4C(O)H) with H2NC6H4Bpin (pin=1,2-O2C2Me4) afforded the boron-containing Schiff bases, 2-HOC6H4C(H)=NC6H4Bpin (1–3a). Similar reactivity with 2-hydroxy-5-nitrobenzaldehyde and 2-hydroxy-1-naphthaldehyde gave the corresponding Schiff bases (1-3b) and (1-3c), respectively. Reaction of Schiff bases (2) and (3) with palladium acetate or Na2PdCl4 afforded complexes of the type PdL2
(4,5), where L=deprotonated Schiff base. The molecular structure of the nitro-salicylaldehyde 4-Bpin palladium complex (5b) was characterized by an X-ray diffraction study. All new palladium compounds have been characterized fully and tested for their antifungal activity against Aspergillus niger and Aspergillus flavus. 相似文献