β-Carboline-based light and pH dual stimuli-responsive ion transporters induce cancer cell death

Light and pH dual-responsive ion transporters offer better applicability for cancer due to higher tunability and low cytotoxicity. Herein, we demonstrate the development of pH-responsive β-carboline-based ionophores and photocleavable-linker appended β-carboline-based proionophores to facilitate the controlled transport of Cl- across membranes, leading to apoptotic and autophagic cancer cell death.

Effect of halide ions on the fluorescence properties of 3-aminoquinoline in aqueous medium

Fluorescence (FL) quenching of 3-aminoquinoline (3AQ) by halide ions Cl - Br - and I - has been explored in an aqueous acidic medium using the steady-state and time-domain FL measurement techniques. The halide ions showed no significant change in the absorption spectra of 3AQ in an aqueous acidic medium. The FL intensity is strongly quenched by I - ions and the order of FL quenching by halide ions is I - > Br - > Cl - . The decrease in FL lifetime along with a reduction in FL intensity of 3AQ suggested the dynamic nature of quenching. The obtained value of K SV was 328 M - 1 for I - ions and 119 M - 1 for Br - ions and the value k q was around 1.66 × 10 10 M - 1 s - 1 and 6.02 × 10 9 M - 1 s - 1 , respectively. Thus, the observations suggest that the likely governing mechanism for FL quenching should be an electron transfer process and the involvement of the heavy atom effect.

Photophysics and luminescence quenching of carbon dots derived from lemon juice and glycerol

During the past decade, carbon dots have emerged as a fascinating class of luminescent nanomaterials with versatile application potentials in bioimaging, labeling, photocatalysis and optoelectronics. Currently, intensive research is concentrated on understanding the intriguing optical properties of these promising materials and their utility as luminescence sensors. In this article, we describe the photoluminescence of carbon dots obtained from a bioresource (lemon juice) and from a small molecule precursor (glycerol), especially the quenching of their emission by nitrobenzene and Hg²⁺ ions, as representative cases. Stern-Volmer analysis using steady-state and time-resolved emission measurements, suggests the involvement of both transient quenching and dynamic quenching mechanisms in the interaction of the carbon dots with nitrobenzene. The radius of the quenching sphere is estimated to be slightly greater than the contact distances between the respective carbon dots and nitrobenzene, which is in reasonable agreement with the "sphere of action" model for transient quenching. In the interaction with Hg²⁺ ions, electrostatic attraction plays a major role, and the quenching mechanism involves predominantly static and dynamic quenching. The static quenching constant matches well with the binding constant of the carbon dots with the metal ion.