Fluorescent Molecule Probe Research Articles

Densification and polyelectrolyte assisted fabricating laminated wood composites for outstanding flame retardancy and mechanical properties

Laminated wood composites have widely used in construction, furniture and decoration; however, it remains a great challenge to address the trade-off between flame retardancy and mechanical strength in applications. In this work, we reported a strategy for fabricating a flame-retardancy-improved and mechanically strengthened laminated wood composites via delignification, densification and self-assembly of polyelectrolyte. The delignification significantly increased the porosity of wood cell walls, facilitating the impregnation and accumulation of an intermediate adhesion molecule of polyethyleneimine (PEI) within wood cell walls. It provided a sticky bridge to enhance crosslinking network with ammonium polyphosphate (APP) and wood cell walls in process of densification. Hence, a densely-laminated wood coordination with PEI/APP flame-retardant layer can enable excellent flame-retardant properties with an increase of 77.30% in limited oxygen index and a significant decrease of 24.22% in peak heat release rate (120 s) compared to control laminated wood composite. Meanwhile, the strains transferred more uniformly in the interior of wood composites across the stable crosslinking network via digital image correlation (DIC), resulting in an enhanced bonding strength. Besides, the permeation and distribution of PEI within wood cell walls can be successfully observed with the fluorescence imaging by chemical grafted the fluorescent molecule probe. This work offered a strategy for designing wood composite with high mechanical properties and flame-retardant for construction applications.

Tracking of transplanted human umbilical cord-derived mesenchymal stem cells labeled with fluorescent probe in a mouse model of acute lung injury.

The aim of the present study was topreliminarily visualize the distribution of humanumbilical cord-derived-mesenchymal stem cells (hUC-MSCs) in treating acute lung injury (ALI) using a targeted fluorescent technique. Anovel fluorescent molecule probe was first synthesized via the specific binding of antigen and antibody in vitro to label the hUC-MSCs. Two groups of mice, comprising a normal saline (NS)+MSC group and lipopolysaccharide (LPS)+MSC group, were subjected to optical imaging. At 4 h following ALI mouse model construction, the labeled hUC-MSCs were transplanted into the mice in the NS+MSC group and LPS+MSC group by tail vein injection. The mice were sacrificed 30 min, 1 day, 3 days and 7 days following injection of the labeled hUC-MSCs, and the lungs, heart, spleen, kidneys and liver were removed. The excised lungs, heart, spleen, kidneys and liver were then detected on asmall animal fluorescent imager. The fluorescent results showed that the signal intensity in the lungs of the LPS+MSC group was significantly higher, compared with that of the NS+MSC group at 30 min (3.53±0.06×10−4, vs. 1.95±0.05×10−4 scaled counts/sec), 1 day (36.20±0.77×10−4, vs. 23.45±0.43×10−4 scaled counts/sec), 3 days (11.83±0.26×10−4, vs. 5.39±0.10×10−4 scaled counts/sec), and 7 days (3.14±0.04×10−4, vs. 0.00±0.00×10−4 scaled counts/sec; all P<0.05). The fluorescence intensity in the liver of the LPS+MSC group, vs. NS+MSC group was measured at 30 min (0.00±0.00×10−4, vs. 0.00±0.00×10−4 scaled counts/sec); 1 day (5.53±0.08×10−4, vs. 5.44±0.16×10−4 scaled counts/sec); 3 days (0.00±0.00×10−4, vs. 8.67±0.05×10−4 scaled counts/sec); 7 days (0.00±0.00×10−4, vs. 0.00±0.00×10−4 scaled counts/sec). The signal intensity of the heart, spleen and kidneys was minimal. In conclusion, the novel targeted fluorescence molecular probe was suitable for tracking the distribution processes of hUC-MSCs in treating ALI.

Liquid temperature measurement method in microchannels by using fluorescence polarization

A novel optical method that can measure fluid temperature at the microscopic scale by measuring fluorescence polarization is described in this paper. The measurement is much less influenced by fluorescence quenching effects, which is a significant issue in conventional laser-induced fluorescence methods. Therefore, the effects of the other properties of the fluid can be reduced considerably in the proposed method, thus has the potential of leading to greater reliability in measuring the temperature. An experiment was performed in a microchannel flow by using fluorescent molecule probes. The relationship between the fluid temperature and the measured fluorescence polarization degree is evaluated to derive the correlation curve. In addition, the effects of the fluid viscosity and fluid pH on the fluorescence polarization degree are discussed to evaluate the influence of the quenching effects. The results showed that the fluorescence polarization is considerably less sensitive to the quenching factors as compared with the fluorescence intensity measurements. Furthermore, a strong linear correlation between the polarization degree and the fluid temperature was obtained. This relationship agreed well with the theoretical one qualitatively and confirmed the validity of the measurements and feasibility of the proposed method.

Micro-scale temperature measurement method using fluorescence polarization

A novel method that can measure the fluid temperature in microscopic scale by measuring the fluorescence polarization is described in this paper. The measurement technique is not influenced by the quenching effects which appears in conventional LIF methods and is believed to show a higher reliability in temperature measurements. Experiment was performed using a microchannel flow and fluorescent molecule probes, and the effects of the fluid temperature, fluid viscosity, measurement time, and pH of the solution on the measured fluorescence polarization degree are discussed to understand the basic characteristics of the present method. The results showed that fluorescence polarization is considerably less sensible to these quenching factors. A good correlation with the fluid temperature, on the other hand, was obtained and agreed well with the theoretical values confirming the feasibility of the method.

Cholesterol modulation of lipid intermixing in phospholipid and glycosphingolipid mixtures. Evaluation using fluorescent lipid probes and brominated lipid quenchers

Carbazole- and indole-labeled phospholipids have been used to monitor the homo- or heterogeneity of lipid mixing in several types of lipid bilayers combining a brominated and a nonbrominated lipid with varying amounts of cholesterol. Experimental quenching curves (relating the normalized probe fluorescence intensity to the mole fraction of brominated lipid) show a characteristic smooth, monophasic form for homogeneous liquid-crystalline lipid mixtures. However, for mixtures exhibiting lipid lateral segregation, such curves show marked perturbations in form over the region of composition where segregation occurs. Using this approach, it is found that high mole fractions of cholesterol (40-50 mol %) promote the formation of apparently homogeneous solutions in mixtures of disaturated and monounsaturated phosphatidylcholines (PCs) that exhibit extensive thermotropic phase separations in the absence of sterol. At only slightly lower levels of cholesterol, however, these systems exhibit inhomogeneous lipid mixing over a wide range of relative proportions of the two PC components. Mixtures of cerebroside and monounsaturated PCs, even at high bilayer cholesterol contents, exhibit significant inhomogeneity in lipid mixing over a wide range of cerebroside/PC ratios. Phase-separating PC/PC and PC/cerebroside mixtures can readily form long-lived metastable solutions when the level of the higher-melting component in the liquid-crystalline phase exceeds its equilibrium solubility by as much as 20-30 mol %; this tendency is significantly increased by cholesterol. Cholesterol shows no significant ability to enhance lipid intermixing in a third type of phase-separating lipid system, combining a monounsaturated PC with a monounsaturated phosphatidic acid--calcium complex. Experiments using cleavable phospholipid conjugates, linking a fluorescent lipid to a brominated lipid, suggest that each fluorescent molecule probes a local lipid domain comprising approximately less than 40-50 nearby acyl chains.

The study of slow relaxation of charged centres in insulator–semiconductor structures using fluorescent molecule probes

The insulator charge relaxation and corresponding change of the fast surface state in the semiconductor–oxide system are investigated. The fluorescence of adsorbed dye molecules is used for the differential anlaysis of the electronic and ionic charge relaxation in an insulator. It is found that charge relaxation is accompanied by the following effects: fluorescence decay, spectral shift of fluorescence maximum, and the change of the fluorescence anisotropy coefficient. [Russian Text Ignored].