Fluorescence Of P1 Research Articles

Bifunctional fluorescent probe for fluoride and copper(Ⅱ) based on perylene diimide derivative and its application in cell imaging

A bifunctional fluorescent probe P1 based on perylene diimide derivative (PDI) was developed, demonstrating high sensitivity and selectivity for the rapid detection of fluoride (F-) and copper (Cu2+). The fluorescence of P1 was quenched upon interaction with F- and enhanced upon interaction with Cu2+. The concentration ranges for fluorescent detection of F- and Cu2+ are 0 ∼ 4 × 10-5 M and 0 ∼ 2.4 × 10-5 M, respectively. The stoichiometry of the complex formed between Cu2+ and P1 or F− and P1 was 1:1. The probe displays detection limits of 0.16 and 0.21 μM and binding constants (Ksv) of 3.92 × 104 and 1.72 × 104 M−1 for the detection of F- and Cu2+, respectively. The sensing mechanism and binding mode of P1 with F- and Cu2+ were investigated. The fluorescence quenching/enhancement of P1 was controlled by a photoinduced electron-transfer (PET) process. Furthermore, the ability of the probe to detect intracellular F- and Cu2+ was assessed using cell imaging techniques.

Enhanced sensing ability of fluorescent chemosensors with triphenylamine-functionalized conjugated polyfluorene

This paper reports the multifunctional responsive fluorescence chemosensory phenomena of two terpyridine-functionalized conjugated polyfluorenes (PFs), poly[2,7-(9,9-dihexylfluorene)-alt-4′-((4-[N,N-(4-phenyl)amino]styryl)phenyl)-2,2′:6′,2″-terpyridine] (P1) and poly[2,7-(9,9-dihexylfluorene)-alt-4′-phenyl-2,2′:6′,2″-terpyridine] (P2), which were exposed to solvents, metal ions, and protons through Suzuki polymerization. Compared with P2, P1 exhibited enhanced sensing ability that resulted from efficient interactions between the specific triphenylamine-linked terpyridine units with protons and metal ions. P1 and P2 both showed high sensitivity toward Cu2+, with the Stern-Volmer constants of 2.30×105M−1 and 1.05×105M−1, respectively. Because of the very high stability constants of the CN−–Cu2+ complexes, the fluorescence of P1 and P2 solutions that were quenched by Cu2+ recovered upon addition of trace CN−, with a detection limit as low as 3.7×10−6M−1 and 5.2×10−6M−1 for P1 and P2, respectively. P1 showed fluorescence quenching when pH decreased from 5.0 to 1.0; however, a pH of 13.0 had little effect on fluorescence intensity. Our results suggest that P1 is a promising material for chemosensory applications.

Fluorescent probes for Cu2+, Hg2+ and amino acids in aqueous solutions based on two mechanisms

The new polythiophene-based conjugated polymers Poly{3-[(4-{[2-(dimethylamino)ethyl]amino}cyclohexylidene)methyl]thiophene} (P1), Poly{3-[(4-{[3-(dimethylamino)propyl]amino}cyclohexylidene)methyl]thiophene} (P2) and Poly{3-{[4-(4-methylpiperazin-1-yl)cyclohexylidene]methyl}thiophene} (P3) have been synthesized by FeCl3 oxidative polymerization. Among the common metal ions tested, P1, P2 and P3 exhibited high selectivity and sensitivity toward Hg2+ in methanol aqueous solutions at pH 3 with a turn-off mode in which the detection limit of P3 for Hg2+ reached a level of 10−8M. Additionally, the fluorescence of P1 in Tris–HCl buffer solution could be dramatically quenched in the presence of Cu2+ with a detection limit of 10−9M. These sensing processes for Hg2+ and Cu2+ have been shown to be mediated by electrostatic effects and complexation. In addition, the P1–Cu2+ system was also employed as a turn-on fluorescence probe for the label-free detection of amino acids.

Fluorescence enhancement of water-soluble porphyrin-containing conjugated polymer induced by DNA and cellular imaging in living cells

A cationic conjugated polyelectrolyte (P1) containing porphyrin, fluorene and phenylene moieties was successfully synthesized by Suzuki coupling reaction. Since P1 showed two independent maximum absorption peaks at 368 and 430nm, the fluorescence spectrum of P1 was dependent upon excitation wavelength. P1 showed strong emission upon excited at 378nm with a maximum emission peak at 450nm. Interestingly, the emission at 450nm was blue-shifted to 430nm and the approximate 95% fluorescence of P1 was quenched upon excitation at 425nm, accompanying presence of a new emission peak at ∼625nm. However, upon excited at 425nm, 20- and 3-folds increase of emission band at 430 and 625nm of P1 were observed in presence of DNA, respectively. This is the first report on fluorescence enhancement of porphyrin-containing conjugated polyelectrolyte induced by DNA, allowing design of an effective fluorescence turn-on DNA probe. In addition, P1 could be utilized as a fluorescent probe for cellular imaging of human adult skin fibroblast cells, where blue fluorescence was observed in the cytoplasm. The CCK-8 assay showed that the cytotoxicity of P1 was significantly low.

Conjugated polyelectrolyte-Ag+ fluorescent switch for biothiol sensing

A new “off-on” switch for sensitive and selective fluorescence detection of biothiols[glutathione(GSH), cysteine(Cys) and homocysteine(Hcy)] was developed based on an anionic conjugated polyelectrolyte(CPE), pyridyl-functionalized poly(phenylene ethynylene)(P1). The fluorescence of P1 can be significantly quenched by Ag+ due to complexation-mediated interpolymer aggregation. Furthermore, biothiols can efficiently recover the fluorescence intensity of P1 as a result of the stronger binding between thiol group and Ag+, which dissociates P1 from the P1/Ag+ complex and disrupts interpolymer aggregation. Under optimum conditions, a good linear relationship in a range of 100–4200 nmol/L is obtained for GSH with a detection limit of 80 nmol/L(S/N=3). As a result of specific interaction between the thiol group and Ag+, the proposed method shows a high selectivity for biothiols. In addition, the CPE-based fluorescence “off-on” switch has been used to quantitatively detect total biothiols in cell lysates.

Metal complex of polymer with 2-(pyridin-2-yl)-1H-benzo[d]imidazole unit as a selectivity-tunable chemosensor for amino acids

A novel 2-(pyridin-2-yl)-1H-benzo[d]imidazole based conjugated polymer (P1) was synthesized and characterized. The binding and recognition behavior of P1 toward the metal ions and amino acids were investigated. The fluorescence of P1 can be completely quenched by Cu2+ and Ni2+ through a photoinduced electron transfer process, resulting in the formation of metal complexes with polymer ([P1-Cu2+] and [P1-Ni2+]), which indicates that P1 is a selective chemosensor for Cu2+ and Ni2+. Moreover, in situ formed [P1-Cu2+] complex showed excellent fluorescence “turn on” properties with high selectivity toward Cys, while [P1-Ni2+] complex with high selectivity toward His and Tryp. These complexes are promising chemosensors for amino acids due to fast response time (less than 5min), high selectivity and high sensitivity (detection limit concentration is 0.1ppm for Tryp). Hence, a facile method to tune the detection selectivity of conjugated polymeric chemosensor with metal ions has been developed.

Aggregation-Induced Amplified Quenching in Conjugated Polyelectrolytes with Interrupted Conjugation

A pair of anionic conjugated polyelectrolytes that contain three-ring (phenylene ethynylene) units linked by a single -CH(2)- or -O- tether (P1 and P2, respectively) are studied. The linkers serve to interrupt the π conjugation along the polymer backbone. Fluorescence spectroscopy reveals that P2 forms a fluorescent aggregate in methanol and water; however, the fluorescence of P1 is much weaker in water, and P1 exhibits only weak aggregate fluorescence. Fluorescence quenching of the polymers was examined using methyl viologen (MV(2+)) as a cationic quencher. P1 shows only a weak amplified quenching effect, with a Stern-Volmer quenching constant of K(SV) ≈ 6 × 10(5) M(-1) in methanol. Interestingly, for P2 in methanol, the aggregate emission is strongly quenched with K(SV) ≈ 5 × 10(6) M(-1), which is comparable to the highest quenching efficiency observed for fully π-conjugated polyelectrolytes. By contrast, the monomer emission is quenched much less efficiently, with K(SV) ≈ 2 × 10(5) M(-1). The results are explained by a model in which -O- linked polymer P2 is able to fold into a helical conformation in solution, which facilitates the formation of extended π-stacked aggregates allowing long-distance exciton transport.