Near-infrared fluorogenic receptor for selective detection of cysteine in blood serum and living cells

Near-Infrared Fluorescence Imaging Sensor with Laser Diffuser for Visualizing Photoimmunotherapy Effects under Endoscopy

The drug efficacy evaluation of tumor-selective photosensitive substances was expected to be enabled by imaging the fluorescence intensity in the tumor area. However, fluorescence observation is difficult during treatments that are performed during gastrointestinal endoscopy because of the challenges associated with including the fluorescence filter in the camera part. To address this issue, this study developed a device that integrates a narrow camera and a laser diffuser to enable fluorescence imaging through a forceps port. This device was employed to demonstrate that a laser diffuser with an NIR fluorescence imaging sensor could be delivered through a 3.2 mm diameter port. In addition, fluorescence images of Cetuximab-IR700 were successfully observed in two mice, and the fluorescence intensity confirmed that the fluorescence decayed within 330 s. This device is expected to have practical application as a tool to identify the optimal irradiation dose for tumor-selective photosensitive substances under endoscopy.

Simple Fluorescence Sensing Approach for Selective Detection of Fe3+ Ions: Live-Cell Imaging and Logic Gate Functioning

A pyrene-based fluorescent chemosensor APSB [N-(pyrene-1-ylmethylene) anthracen-2-amine] was designed and developed by a simple condensation reaction between pyrene carboxaldehyde and 2-aminoanthracene. The APSB fluorescent sensor selectively binds Fe³⁺ in the presence of other metal ions. Apart from this, APSB shows high selectivity and sensitivity toward Fe³⁺ ion detection. The detection limit for APSB was 1.95 nM, and the binding constant (K _b) was obtained as 8.20 × 10⁵ M^-1 in DMSO/water (95/5, v/v) medium. The fluorescence quantum yields for APSB and APSB-Fe³⁺ were calculated as 0.035 and 0.573, respectively. The function of this fluorescent sensor APSB can be explained through the photo-induced electron transfer mechanism which was further proved by density functional theory studies. Finally, a live-cell image study of APSB in HeLa cells was also carried out to investigate the cell permeability of APSB and its efficiency for selective detection of Fe³⁺ in living cells.