A selective and sensitive sequential ratio/“turn-off” dual mode fluorescent chemosensor for detection of copper ions in aqueous solution and serum

An aqueous mediated ultrasensitive facile probe incorporated with acrylate moiety to monitor cysteine in food samples and live cells

A colorimetric probe TQA ((E)-4-(((8-(sec-butoxy)-2,3,6,7-tetrahydro-1H,5H-pyrido[3,2,1-ij]quinolin-9-yl)methylene)amino)benzylacrylate) possessing greater potent towards the sensing of cysteine was successfully synthesized and characterized. The aqueous soluble probe TQA detects Cys based on "ON-OFF" effect with excellent absorbance and emission properties. The probe TQA detects Cys up to its ultra-low level concentration of 1.5 nM and also quantifies the Cys up to 5.05 nM with the quicker response time of 140 s (2.3 min). In addition, the color change produced by the probe TQA on integrated with Cys was also identified easily via paper strip, cotton wool buds and RGB color picker app in smart mobiles. Further, the admirable selectivity and sensitivity of the probe TQA towards Cys extends its utility towards food samples and imaging of live HeLa cells.

Development in Fluorescent OFF-ON Probes Based on Cu2+ Promoted Hydrolysis Reaction of the Picolinate Moiety

Anions and cations have a key role in our normal life. Cu²⁺ ion is a crucial trace element accountable for the part of several cellular enzymes and proteins, including cytochrome c oxidase, dopamine monooxygenase, Cu/Zn superoxide dismutase, and ceruloplasmin. WHO has found the extreme acceptable level of Cu²⁺ ions in drinking water is up to 2.0 ppm. Excess use of Cu²⁺ ions is associated with various human genetic disorders. Thus, the visualization of Cu²⁺ ions to avoid its toxic effects in chemical and biological systems is significant. In this review we have summarized sensors based on catalytic hydrolysis of picolinate to detect Cu²⁺ ions. The sensors based on hydrolysis of picolinate are very selective as compared to the other sensors for Cu²⁺ ions detection. We have focused on describing the structure, spectral properties, detection limits, and bioimaging model of the sensors.

A ratiometric fluorescent probe for sensing hypochlorite in physiological saline, bovine serum albumin and fetal bovine/calf serum

HClO/ClO^-, as one of important reactive oxygen species, is a highly reactive unavoidable by-product generated from normal cell metabolism. In recent years, efficient method for detectiing HClO/ClO^- is of great important to research its pathological or physiological function in bio-systems. In this work, we have constructed a fluorescent probe (P-Hc) with ratiometric signal for sensing HClO/ClO^- in aqueous solution, physiological saline and different serums based on 2-(benzo[d]thiazol-2-yl)phenol dye. The structure of P-Hc was characterized by NMR and HRMS spectrum. The sensing mechanism has also been verified by ¹H NMR spectrum. The P-Hc displays good sensitivity and selectivity for HClO/ClO^- with a limit of detection (LOD) of 2.03 × 10^-6 M. Furthermore, P-Hc has been applied for sensing HClO/ClO^- in physiological saline and different serums. Thus, P-Hc may provide a novel method for ratiometric fluorescent sensing HClO/ClO^- in bio-samples.

Lipid droplet polarity decreases during the pathology of muscle injury as revealed by a polarity sensitive sensor

Revealing the relationship between lipid droplets (LDs)polarity and disease is indispensable in clinicopathological diagnosis. So far, muscle injury is often ignored as it is not life-threatening as cardiovascular and cerebrovascular diseases, making the exploration of the internal relationship between muscle injury and LDs polarity a gray area. Herein, a fluorescent probe (CCB) with powerful polar-sensitive as well as precise LDs targeting was designed for visualizing the LDs polarity in the pathology of muscle injury. By means of the probe CCB, the identification of cancer cells and the monitoring of LDs polarity changes in dysfunctional cells were successfully realized. Furthermore, the penetration ability of CCB in tissues of mice was tested to verify the applicability of the probe in organisms. Importantly, by CCB, the relationship between muscle damage and LDs polarity was explored, revealing that muscle damage caused a significant decrease in LDs polarity accompanied by a significant increase in fluorescence. Most importantly, it is the first time to reveal the relationship between muscle damage and LDs polarity. Therefore, the probe CCB will be a powerful monitoring platform for diagnosing related diseases caused by abnormal LDs polarity.

A novel bifunctional-group salamo-like multi-purpose dye probe based on ESIPT and RAHB effect: Distinction of cyanide and hydrazine through optical signal differential protocol

A novel bifunctional-group multi-purpose dye probe p-TNS has been designed and synthesized. The probe p-TNS has unique excited-state intramolecular proton transfer (ESIPT) and resonance-assisted hydrogen bonding (RAHB) coupled system, was confirmed to detect cyanide and hydrazine by blocking the ESIPT effect. Cyanide can change the fluorescence of the solution from bright green to orange-red (116 nm Stokes shift), while hydrazine causes the bright green fluorescence to be quenched. The recognition mechanism of the probe p-TNS to CN^- and N₂H₄ was proposed reasonably through spectral characterizations and theoretical calculations. Combined with theoretical calculations, it was speculated that the solvent dependence may be caused by the ICT effect in the molecule. The probe p-TNS could be prepared into test strips for the detection of cyanide and hydrazine. In addition, the probe molecule can also be used to detect trace amounts of cyanide in agricultural products, and respond to gaseous hydrazine by direct contact, indicating that the probe p-TNS has good practical application prospects. Therefore, this molecular framework provides a new way of thinking about detecting multiple target substances.

Substituent effects on opticalproperties of pyrrolizine-fused BOPYIN

Three new pyrrolizine-fused BOPYINs (DAB-H, DAB-OMe, DAB-ester) have been reported in 26-35% yield. The relationship between structures and optical spectra was investigated, which all the compounds show large Stokes Shift (3146-3884 cm^-1) and high quantum yield (up to 99%) in solvents. Among these dyes, the decoration of electron donating/withdrawing groups on indole, pyrrole and pyrrolizine units has a significant impact on optical properties, especially emission spectra. The results suggested that electron withdrawing group on pyrrole and pyrrolizine units has hypsochromic shift on emission spectra (DAB-H, DAB-OMe, DAB-ester versus DAB-1,4,5). The optimized structure, electron distribution on frontier molecular orbital, energy gap and simulated stick spectra of DABs are discussed by Density Functional Theory (DFT) calculation. We claim the agreement between the experimental and theoretical absorption spectra.

A novel “turn-on” fluorescent probe based on naphthalimide for the tracking of lysosomal Cu2+ in living cells

The lysosome-targeted probe CuNI exhibits highly effective fluorescence detection ability for Cu²⁺ in aqueous solution and cells. The fluorescent enhancement is due to the Cu²⁺-catalyzed hydrolysis of CuNI and the AIE effect of the hydrolysate MFNI.