# BODIPY-Based Nanomaterials--Sensing and Biomedical Applications
## 2 Metallic Nanoparticles@BODIPY
### Sensing Applications
#### 2.1.1.
The authors confirmed the selectivity of the nanoprobe and its reproducibility within a few cycles of lead detection and further sensor stripping with EDTA. Moreover, the fluorescence signal was unchanged in the pH range of 3-11. Thus, they concluded that their nanoprobe might be used in the physiological environment. The usability of the lead nanodetector was checked in the living cells. Pb(ClO\({}_{4}\))\({}_{2}\) and a nanoprobe were added to the HeLa cells, and then the fluorescence signal was measured. Figure 6: Schematic representation of the conjugates based on BODIPY dyes and antibodies deposited on ferrite/polystyrene nanosheets [59]. The authors found that cells treated with lead ions showed 10-fold higher emission intensity in comparison to free-lead cells. Moreover, the sensor was active in many cycles of lead detection stripping [61]. Heavy metal pollution represents a considerably severe ecological issue and can invoke numerous disorders in the human organism, including cancer. In 2020, [PERSON] and [PERSON] de  
Figure 8: The chemical structure of magnetite nanoparticles coated with silica and BODIPY dyes [61]. Figure 7: The chemical structure of nickel nanoparticles coated with silica and BODIPY dyes [60]. signed a new fluorescent superparamagnetic nanoparticle (F-SPION) that revealed a selective fluorescent response against ions Cr\({}^{6+}\) in the strongly acidic medium [62; 63]. F-SPION was derived from superparamagnetic magnetite particles coated with silica and modified by 3-aminopropyltrimethoxysilanes (APTMS) bound to \(p\)-tolyl BODIPY moieties (Figure 9). According to the conducted X-ray diffraction analysis, F-SPION is 18 nm in diameter, while fluorescence spectroscopy revealed its single emission at 510 nm. The fluorescence was also measured in the presence of other cations (Ag\({}^{+}\), Pb\({}^{2+}\), Mn\({}^{2+}\), K\({}^{+}\), Ba\({}^{2+}\), Mg\({}^{2+}\), Cr\({}^{3+}\), Cd\({}^{2+}\), Ca\({}^{2+}\), Hg\({}^{2+}\), Cu\({}^{2+}\), Al\({}^{3+}\), Fe\({}^{2+}\), Sr\({}^{2+}\), Fe\({}^{3+}\), Zn\({}^{2+}\), Co\({}^{2+}\), and Ni\({}^{2+}\)) as perchlorate salts, but only Cr(VI) ions provoked notable \"ON-OFF\" emission changes significantly lowering the fluorescent intensity. Experimental studies on pH were conducted in the range of 1-8 and established the value of 1 as the most suitable level for Cr\({}^{6+}\) evaluation. The limit of ion detection was determined as 3.3 (\(\pm\)1) mcg/mL [62]. In the following article, the authors reported the formation of two other BODIPY-containing magnetite-based nanosensors named Fe\({}_{3}\)O\({}_{4}\)@SiO\({}_{2}\)-TPED-BODIPY and Fe\({}_{3}\)O\({}_{4}\)@SiO\({}_{2}\)-TMPTA-BODIPY [62]. The new compositions shared a lot of similarities with F-SPION in terms of structure and physicochemical attributes. The key difference was the choice of silane agents during the synthesis process: for Fe\({}_{3}\)O\({}_{4}\)@SiO\({}_{2}\)-TPED-BODIPY, it was \(N\)-[3-(trimethoxysil)]propylhelenediamine (TPED), resulting in 18.5 nm nanospheres, while for Fe\({}_{3}\)O\({}_{4}\)@SiO\({}_{2}\)-TMPTA-BODIPY \(N^{1}\)-(3-trimethoxysilpropyl)-diethylene-triamine (TMPTA) was used, affording the approximate size of 19 nm. The new nanoparticles endured the same set of physicochemical characterizations and proved to be effective sensing instruments towards Cr(VI) ions determination. Based on the emission changes in the fluorescence intensities, the limit of Cr\({}^{6+}\) detection was ascertained as 2.2 (\(\pm\)1) mcg/mL for the TPED-nanosensor and 3.1 (\(\pm\)2) mcg/mL for the TMPTA-nanosensor (pH = 1). The fluorescence of the free Fe\({}_{3}\)O\({}_{4}\)@SiO\({}_{2}\)-TPED-BODIPY showed higher intensity (286 nm vs. 253 nm) and demonstrated a 70% drop in response to chromium ions (ligand:metal binding ratio 2:1), while in the case of Fe\({}_{3}\)O\({}_{4}\)@SiO\({}_{2}\)-TMPTA-BODIPY-Cr(VI), the decrease was 77% (ligand:metal binding ratio 1:1) [62].