A highly selective and sensitive fluorescence probe with A-π-D-π-A structure for detection of Ag +

Development of Safirinium dyes for new applications: fluorescent staining of bacteria, human kidney cells, and the horny layer of the epidermis

Low-molecular synthetic fluorophores are convenient tools in bioimaging applications. Several derivatives of Safirinium dyes as well as their reactive N-hydroxysuccinimide (NHS) esters bearing diverse substituents were synthesized and evaluated experimentally in terms of their lipophilicity by means of reverse-phase and immobilized artificial membrane high-performance liquid chromatography. Subsequently, the selected compounds were employed as novel cellular imaging agents for staining Gram-positive and Gram-negative bacteria, human kidney cell line, as well as human skin tissue. The analyzed dyes allowed for visualization of cellular structures such as mitochondria, endoplasmic reticulum, and cellular nuclei. They proved to be useful in fluorescent staining of stratum corneum, especially in the aspect of xenobiotic exposure and its penetration into the skin. The best results were obtained with the use of moderately lipophilic NHS esters of Safirinium Q. The development of Safirinium dyes is a promising alternative for commercially available dyes since the reported molecules have low molecular masses and exhibit efficient staining and remarkable water solubility. Moreover, they are relatively simple and low-cost in synthesis.

Controlling the ligands of CdZnTe quantum dots to design a super simple ratiometric fluorescence nanosensor for silver ion detection

A super simple ratiometric fluorescence nanosensor has been fabricated by controlling the ligands of CdZnTe quantum dots (QDs), allowing the sensitive and visual detection of silver ions (Ag⁺). The green-emitting L-cysteine-protected CdZnTe QDs (Lcys-CdZnTe QDs) had a specific response to Ag⁺ and were used as the reporting probe, while the red-emitting N-acetyl-L-cysteine-protected CdZnTe QDs (NAC-CdZnTe QDs) showed no obvious response to all tested metal ions and were selected as the reference probe. Simply mixing them without any encapsulated synthesis ultimately produced a time-saving, low-cost detection method, allowing the sensitive and visual detection of Ag⁺ in samples. The proposed nanosensor exhibited a linear range of 0.5-4.0 μM along with a detection limit of 0.17 μM, and has been successfully applied in real tap water and lake water samples. This nanosensor also showed obvious color changes in the detection process and has potential in visual semi-quantitative detection. Our approach may provide a general and feasible strategy for designing ratiometric fluorescence nanosensors, which will attract a wide range of interest in sensing-related fields.