Photoinduced charge-separated molecular probe for ultrasensitive spectrum analysis and rapid colorimetric detection of platinum ions.

Increased utilization of platinum ions in chemicals and drugs escalates environmental pollution and toxicity associated with Pt ions. However, current analysis and detection strategies of Pt ions display limited sensitivity due to the similar inert metal nature of platinum to gold. Herein, a photoinduced charge-separated molecule (MTPA)2Ab was synthesized as a probe for enhanced sensitive selection of Pt ions. Long-lived charge-separated states generated upon exposure to 365 nm light lead to a stable complex between (MTPA)2Ab and PtCl2/PtCl4 with highly-selectivity via sequential photoinduced electron transfers. Owing to the linear relationship of complex characteristic absorption and fluorescence emission intensities to Pt2+/Pt4+ concentrations, ultrasensitive spectrum analysis of Pt ions is achieved with a detection limit of 14.2 nM (2.8 ppb) for Pt2+ and 12.6 nM (2.5 ppb) for Pt4+ by an absorption spectrometer and 9.8 nM (1.9 ppb) for Pt ions (Pt2+/Pt4+) by a fluorescence spectrometer, far less than the reported values. Furthermore, a portable test box is developed based on (MTPA)2Ab test strips due to distinguishable color change with Pt2+/Pt4+ concentrations for rapid colorimetric detection of Pt ions. The results highlight the promise of photoinduced charge-separated molecular probe in ultrasensitive and rapid detection of Pt ions to overcome current limitations of detection strategies.

Cause, Regulation and Utilization of Dye Aggregation in Dye-Sensitized Solar Cells.

As an important member of third generation solar cell, dye-sensitized solar cells (DSSCs) have the advantages of being low cost, having an easy fabrication process, utilizing rich raw materials and a high-power conversion efficiency (PCE), prompting nearly three decades as a research hotspot. Recently, increasing the photoelectric conversion efficiency of DSSCs has proven troublesome. Sensitizers, as the most important part, are no longer limited to molecular engineering, and the regulation of dye aggregation has become a widely held concern, especially in liquid DSSCs. This review first presents the operational mechanism of liquid and solid-state dye-sensitized solar cells, including the influencing factors of various parameters on device efficiency. Secondly, the mechanism of dye aggregation was explained by molecular exciton theory, and the influence of various factors on dye aggregation was summarized. We focused on a review of several methods for regulating dye aggregation in liquid and solid-state dye-sensitized solar cells, and the advantages and disadvantages of these methods were analyzed. In addition, the important application of quantum computational chemistry in the study of dye aggregation was introduced. Finally, an outlook was proposed that utilizing the advantages of dye aggregation by combining molecular engineering with dye aggregation regulation is a research direction to improve the performance of liquid DSSCs in the future. For solid-state dye-sensitized solar cells (ssDSSCs), the effects of solid electrolytes also need to be taken into account.

Exploiting singlet excited state conformation for rational design of highly efficient photoinduced electron transfer molecules.

In spite of the pivotal role of excited state electronic structures as regulation of photoinduced electron transfer (PET) process, the effect of excited state conformation on PET remains elusive. Here we exploit distinguishable emission characters of trans and cis singlet excited states of donor-acceptor-donor ensemble MTPAAZO to reveal that its PET efficiency and rate are closely depended on its singlet excited state conformation. The PET process occurs solely in cis conformation of MTPAAZO singlet excited states. Novel molecule (MTPA)2Ab as-designed with similar structure of MTPAAZO cis singlet excited states shows high PET efficacy and rate, leading to long-lived CS states. Our findings enable the rational design of the novel molecules with highly efficient PET process suitable for charge separation applications.

Quantitative characterization of the regulation of iron metabolism in glioblastoma stem-like cells using magnetophoresis.

This study focuses on different iron regulation mechanisms of glioblastoma (GBM) cancer stem-like cells (CSCs) and non-stem tumor cells (NSTCs) using multiple approaches: cell viability, density, and magnetophoresis. GBM CSCs and NSTCs were exposed to elevated iron concentration, and their magnetic susceptibility was measured using single cell magnetophoresis (SCM), which tracks the magnetic and settling velocities of thousands of individual cells passing through the magnetic field with a constant energy gradient. Our results consistently demonstrate that GBM NSTCs have higher magnetic susceptibility distribution at increased iron concentration compared with CSCs, and we speculate that it is because CSCs have the ability to store a high amount of iron in ferritin, whereas the free iron ions inside the NSTCs lead to higher magnetic susceptibility and reduced cell viability and growth. Further, their difference in magnetic susceptibility has led us to pursue a separate experiment using a quadrupole magnetic separator (QMS), a novel microfluidic device that uses a concentric channel and permanent magnets in a special configuration to separate samples based on their magnetic susceptibilities. GBM CSCs and NSTCs were exposed to elevated iron concentration, stained with two different trackers, mixed and introduced into QMS; subsequently, the separated fractions were analyzed by fluorescent microscopy. The separation results portray a successful label-less magnetic separation of the two populations.