Energy transfer in ternary TbEDTA chelates with a series of dipicolinic acid derivatives

The energy transfer in lanthanoid chelates was studied using the ternary TbEDTA (EDTA ¼ethyl-enediaminetetraacetic acid) chelates with several dipicolinic acid derivatives (pyridine-2,6-dicarboxylic acid (L1, dpa), 4-(9H-fluoren-3-yl)pyridine-2,6-dicarboxylic acid (L2), 4-(dibenzo [b,d]furan-2-yl)pyridine-2,6- dicarboxylic acid (L3), 4-(dibenzo [b,d]thiophen-2-yl)pyridine-2,6-dicarboxylic acid (L4) and 4-(9H-carbazol- 3-yl)pyridine-2,6-dicarboxylic acid (L5)) and spectroscopic methods (absorption and luminescence spectroscopy and the effect of argon treatment and temperature on luminescence lifetime(s)). The results revealed that the ILCT (intra-ligand charge transfer) state is inefficient in exciting the Tb(III) ion and the emissive states of the ligands, as well as the triplet states, act as quenching states by receiving energy back transfer from the Tb(III) ion. The stability constants for these ternary complexes were also determined.</p

Lanthanide-based bulky counterions against aggregation-caused quenching of dyes in fluorescent polymeric nanoparticles

Dye-loaded polymeric nanoparticles (NPs) are promising bioimaging agents because of their available surface chemistry, high brightness, and tunable optical properties. However, high dye loadings can cause the aggregation-caused quenching (ACQ) of the encapsulated fluorophores. Previously, we proposed to mitigate the ACQ inside polymeric NPs by insulating cationic dyes with bulky hydrophobic counterions. In order to implement new functionalities into dye-loaded NPs, here, we extend the concept of bulky counterions to anionic lanthanide-based complexes. We show that by employing Gd-based counterions with octadecyl rhodamine B loaded NPs at 30 wt% versus polymer, the fluorescence quantum yield can be increased to 10-fold (to 0.34). Moreover, Gd-anion provides NPs with enhanced contrast in electron microscopy. A combination of a luminescent Eu-based counterion with a far-red to near-infrared cyanine 5 dye (DiD) yields Forster resonance energy transfer NPs, where the UV-excited Eu-based counterion transfers energy to DiD, generating delayed fluorescence and large stokes shift of similar to 340 nm. Cellular studies reveal low cytotoxicity of NPs and their capacity to internalize without detectable dye leakage, in contrast to leaky NPs with small counterions. Our findings show that the aggregation behavior of cationic dyes in the polymeric NPs can be controlled by bulky lanthanide anions, which will help in developing bright luminescent multifunctional nanomaterials

Multidomain lifestyle intervention benefits a large elderly population at risk for cognitive decline and dementia regardless of baseline characteristics : The FINGER trial

Introduction: The 2-year Finnish Geriatric Intervention Study to Prevent Cognitive Impairment and Disability (FINGER) multidomain lifestyle intervention trial (NCT01041989) demonstrated beneficial effects on cognition. We investigated whether sociodemographics, socioeconomic status, baseline cognition, or cardiovascular factors influenced intervention effects on cognition. Methods: The FINGER recruited 1260 people from the general Finnish population (60-77 years, at risk for dementia). Participants were randomized 1: 1 to multidomain intervention (diet, exercise, cognition, and vascular risk management) and regular health advice. Primary outcome was change in cognition (Neuropsychological Test Battery z-score). Prespecified analyses to investigate whether participants' characteristics modified response to intervention were carried out using mixed-model repeated-measures analyses. Results: Sociodemographics (sex, age, and education), socioeconomic status (income), cognition (Mini-Mental State Examination), cardiovascular factors (body mass index, blood pressure, cholesterol, fasting glucose, and overall cardiovascular risk), and cardiovascular comorbidity did not modify response to intervention (P-values for interaction > .05). Conclusions: The FINGER intervention was beneficial regardless of participants' characteristics and can thus be implemented in a large elderly population at increased risk for dementia. (C) 2017 The Authors. Published by Elsevier Inc. on behalf of the Alzheimer's Association.Peer reviewe

Homogeneous Detection of Avidin Based on Switchable Lanthanide Luminescence

We have developed switchable lanthanide luminescence-based binary probe technology for homogeneous detection of avidin, which is a tetrameric protein. Two different nonluminescent label moietiesa light-absorbing antenna ligand and a lanthanide ion carrier chelatewere conjugated to separate biotins, which is known as avidin’s natural ligand. The assay was based on binding of the two differently labeled biotins on separate binding sites on the target protein and consequent self-assembly of a luminescent complex from the two label moieties. Specific luminescence signal was observed only at the presence of the target protein. The characteristics of the switchable lanthanide luminescence assay were compared to the reference assay, based on lanthanide resonance energy transfer. Both assays had a limit of detection in the low-picomolar concentration range; however, the lanthanide chelate complementation-based assay had wider dynamic range and its optimization was more straightforward. The switchable lanthanide luminescence technology could be further applied to generic protein detection, using reagents that are analogous to the proximity ligation assay principle