Background: Pure 1, 3-diacylglycerols (1, 3-DAG) have been considered to be significant surfactants in food, cosmetics and pharmaceutical industries, as well as the effect on obesity prevention. Methods: In this study, a vacuum-driven air bubbling operation mode was developed and evaluated for the enzymatic synthesis of 1, 3-DAG of saturated fatty acids, by direct esterification of glycerol with fatty acids in a solvent-free system. The employed vacuum-driven air bubbling operation mode was comparable to vacuum-driven N₂ bubbling protocol, in terms of lauric acid conversion and 1, 3-dilaurin content. Results: Some operation parameters were optimized, and 95.3% of lauric acid conversion and 80.3% of 1, 3-dilaurin content was obtained after 3-h reaction at 50°C, with 5 wt% of Lipozyme RM IM (based on reactants) amount. Of the lipases studied, both Lipozyme RM IM and Novozym 435 exhibited good performance in terms of lauric acid conversion. Lipozyme TL IM, however, showed low activity. Lipozyme RM IM showed good operational stability in this operation protocol, 80.2% of the original catalytic activity remained after 10 consecutive batch applications. Some other 1, 3-DAG were prepared and high content was obtained after purification: 98.5% for 1, 3-dicaprylin, 99.2% for 1, 3-dicaprin, 99.1% for 1, 3-dilaurin, 99.5 for 1, 3-dipalmitin and 99.4% for 1, 3-disterin. Conclusion: The established vacuum-driven air bubbling operation protocol had been demonstrated to be a simple-operating, cost-effective, application practical and efficient methodology for 1, 3-DAG preparation.

Biocompatible transition metal complexes dyes emitting in the near-infrared (NIR) region, are highly desirable in fluorescence imaging techniques. However, a high-performance mitochondria-specific labeling NIR probe with high photostability is still lacking. Herein we reported two NIR-emitting cationic iridium(III) complexes [Ir(pbq-g)₂(N^N)]⁺Cl⁻ (pbq-g = phenylbenzo[g]-quinoline; N^N = 2-(1-benzyl-1H-pyrazol-3-yl) pyridine (Ir1) and 2-(1-(naphthalen-1-ylmethyl)-1H-pyrazol-3-yl) pyridine (Ir2)). These two novel Ir(III) complexes with different N^N ligands exhibited similar NIR emission with λ_max at 751 nm for Ir1 and 750 nm for Ir2 in PBS solution, with luminescence quantum yields of around 0.62 for Ir1 and 0.85 for Ir2. These two complexes showed high mitochondrial specificity, superior photostability, high resistance to the loss of the mitochondrial membrane potential and appreciable tolerance to environmental changes, allowing NIR imaging of mitochondrial morphological changes over long periods of time. These excellent photophysical and imaging properties made them promising NIR luminescent tags for applications in bioimaging.

Metal–organic coordination polymers (CPs) have attracted great research interest because they are easy to prepare, porous, flexible in composition, and designable in structure. Their applications in biosensor development, drug delivery, and catalysis have been explored. Lanthanides and nucleotides can form interesting CPs, although most previous works have focused on a single type of metal ligand. In this work, we explored mixed nucleotides and studied their DNA adsorption properties using fluorescently labeled oligonucleotides. Adenosine monophosphate (AMP) and guanosine monophosphate (GMP) formed negatively charged CP nanoparticles with most lanthanides, and thus a salt was required to adsorb negatively charged DNA. DNA adsorption was faster and reached a higher capacity with lighter lanthanides. Desorption of pre-adsorbed DNA by inorganic phosphates, urea, proteins, surfactants, and competing DNA was successively carried out. The results suggested the importance of the DNA phosphate backbone, although hydrogen bonding and DNA bases also contributed to adsorption. The AMP CPs adsorbed DNA more strongly than the GMP ones, and using mixtures of AMP and GMP, continuous tuning of DNA adsorption affinity was achieved. Such CPs were also used as a sensor for DNA detection based on the different affinities of single- and double-stranded DNA, and a detection limit of 0.9 nM target DNA was achieved. Instead of tuning DNA adsorption by varying the length and sequence of DNA, the composition of CPs can also be controlled to achieve this goal.