A Sensitive and Reliable Organic Fluorescent Nanothermometer for Noninvasive Temperature Sensing.

Sensing temperature at the subcellular level is of great importance for the understanding of miscellaneous biological processes. However, the development of sensitive and reliable organic fluorescent nanothermometers remains challenging. In this study, we report the fabrication of a novel organic fluorescent nanothermometer and study its application in temperature sensing. First of all, we synthesize a dual-responsive organic luminogen that can respond to the molecular state of aggregation and environmental polarity. Next, natural saturated fatty acids with sharp melting points as well as reversible and rapid phase transition are employed as the encapsulation matrix to correlate external heat information with the fluorescence properties of the luminogen. To apply the composite materials for biological application, we formulate them into colloidally dispersed nanoparticles by a technique that combines in situ surface polymerization and nanoprecipitation. As anticipated, the resultant zwitterionic nanothermometer exhibits sensitive, reversible, reliable, and multiparametric responses to temperature variation within a narrow range around the physiological temperature (i.e., 37 °C). Taking spectral position, fluorescence intensity, and fluorescence lifetime as the correlation parameters, the maximum relative thermal sensitivities are determined to be 2.15% °C-1, 17.06% °C-1, and 17.72% °C-1, respectively, which are much higher than most fluorescent nanothermometers. Furthermore, we achieve the multimodal temperature sensing of bacterial biofilms using these three complementary fluorescence parameters. Besides, we also fabricate a cationic form of the nanothermometer to facilitate efficient cellular uptake, holding great promise for studying thermal behaviors in biological systems.

[Determination of 5-hydroxymethyl-furfural in root of Achyranthes bidentata expressing different degree of floating sugar].

OBJECTIVE: To study the relation between the content of 5-hydroxymethyl-furfural (5-HMF) and the degree of floating sugar in root of Achyranthes bidentata. METHOD: An HPLC method was applied with a Waters Symmetry C18 3.9 mm x 150 mm (5 microm) column by using methanol-water (12:88) as the mobile phase at a flow rate of 1.0 mL x min(-1) and a UV detection of 280 nm. RESULT: Along with the degree's deepening of floating sugar, the content of 5-HMF varied with the different shades of the sample. The content was 10 times higher in the black sample (highest degree of flowing suger) than that in the yellowish sample (normal). The concentrations of 5-HMT in five yellowish samples of roots of A. bidentata were 0.162 mg x g(-1) to 0.332 mg x g(-1). CONCLUSION: The content increasing of 5-HMF in the root of A. bidentata was related to the degree of flowing sugar.

[HPLC determination of chemical constituents produced in Radix Polygoni Multiflori after processing].

OBJECTIVE: To analysis the changes of two chemical constituents, namely 2, 3-dihydro-3, 5- dihydroxy-6-methyl-4H-pyran-4-one (DDMP) and 5-hydryoxymethyl-furfural (5-HMF) produced in Radix Polygoni Multiflori after processing, with processing time, and to determine the contents of 5-HMF in samples of Radix Polygoni Multiflori and Radix Polygoni Multiflori preparata. METHOD: An HPLC method was applied with a Zobax SB-C18 (3.9 mm x 150 mm, 5 microm) column by a elution using methanol-water (10: 90) as the mobile phase. The detection was set at UV 280 nm. RESULT: The contents of DDMP were increasing with the processing time until 24 hour, followed by a decrease until 60 hour process. The contents of 5-HMF were increasing gradually throughout the 60 hour steaming process. The contents of 5-HMF in 11 samples of Radix Polygoni Multiflori preparata were from 0.013% to 0.101%, and only one in 4 samples of Radix Polygoni Multiflori containing trace amount of 5-HMF. CONCLUSION: The chemical components in Radix Polygoni Multiflori were changed during the processing procedures. Therefore, the processing of Radix Polygoni Multiflori should be controlled and standardized.