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"Turn-on" fluorescence probe integrated polymer nanoparticles for sensing biological thiol molecules.

Ang CY, Tan SY, Lu Y, Bai L, Li M, Li P, Zhang Q, Selvan ST, Zhao Y - Sci Rep (2014)

Bottom Line: Configuration interaction singles (CIS) calculation was performed to confirm the mechanism of this process.A series of sensing studies were carried out, showing that the probe-integrated nanoparticles were highly selective towards biological thiol compounds over non-thiolated amino acids.This development paves a path for the sensing and detection of biological thiols, serving as a potential diagnostic tool in the future.

View Article: PubMed Central - PubMed

Affiliation: Division of Chemistry and Biological Chemistry, Nanyang Technological University, 21 Nanyang Link, Singapore 637371, Singapore.

ABSTRACT
A "turn-on" thiol-responsive fluorescence probe was synthesized and integrated into polymeric nanoparticles for sensing intracellular thiols. There is a photo-induced electron transfer process in the off state of the probe, and this process is terminated upon the reaction with thiol compounds. Configuration interaction singles (CIS) calculation was performed to confirm the mechanism of this process. A series of sensing studies were carried out, showing that the probe-integrated nanoparticles were highly selective towards biological thiol compounds over non-thiolated amino acids. Kinetic studies were also performed to investigate the relative reaction rate between the probe and the thiolated amino acids. Subsequently, the Gibbs free energy of the reactions was explored by means of the electrochemical method. Finally, the detection system was employed for sensing intracellular thiols in cancer cells, and the sensing selectivity could be further enhanced with the use of a cancer cell-targeting ligand in the nanoparticles. This development paves a path for the sensing and detection of biological thiols, serving as a potential diagnostic tool in the future.

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(A) Fluorescence intensity (λ = 477 nm) of ZG-20 NPs after overnight co-incubation with various amino acids and thiol compounds (5.0 mM) in PBS (pH = 7.4) at 37°C (λex = 330 nm). Error bar: n = 3. Inset: Fluorescence images of the resulted NP solutions under UV lamp. From bottom left to top right: ZG-20 NPs treated with DTT, Cys, Hcy, GSH, Methionine (Met), Alanine (Ala), Glycine (Gly), Leucine (Leu), Histidine (His), Isoleucine (Ile), Tryptophan (Trp), Tyrosine (Tyr), Aspartic acid (Asp), Arginine (Arg), Asparagine (Asn), Lysine (Lys), Phenylalanine (Phe), Threonine (Thr), Proline (Pro), Serine (Ser), Valine (Val), Glutamine (Gln) and Glutamic acid (Glu). (B) Fluorescence spectra of the NP solution after overnight co-incubation with various concentrations of Cys in PBS (pH = 7.4) at 37°C.
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f3: (A) Fluorescence intensity (λ = 477 nm) of ZG-20 NPs after overnight co-incubation with various amino acids and thiol compounds (5.0 mM) in PBS (pH = 7.4) at 37°C (λex = 330 nm). Error bar: n = 3. Inset: Fluorescence images of the resulted NP solutions under UV lamp. From bottom left to top right: ZG-20 NPs treated with DTT, Cys, Hcy, GSH, Methionine (Met), Alanine (Ala), Glycine (Gly), Leucine (Leu), Histidine (His), Isoleucine (Ile), Tryptophan (Trp), Tyrosine (Tyr), Aspartic acid (Asp), Arginine (Arg), Asparagine (Asn), Lysine (Lys), Phenylalanine (Phe), Threonine (Thr), Proline (Pro), Serine (Ser), Valine (Val), Glutamine (Gln) and Glutamic acid (Glu). (B) Fluorescence spectra of the NP solution after overnight co-incubation with various concentrations of Cys in PBS (pH = 7.4) at 37°C.

Mentions: The detection selectivity of probe-integrated ZG-20 NPs was evaluated by conducting the co-incubation of the NPs (0.66 mg mL−1) with various amino acids and thiol compounds (5.0 mM) in PBS buffer overnight. In this study, we used dithiolthretol (DTT) to investigate the response of the NP system. Although DTT is not considered as a biological thiol compound, it is a well-known thiolated reducing agent and could serve as a positive control for comparison. After the overnight incubation, we measured the fluorescence intensity of the NP solution at 477 nm under the excitation wavelength of 330 nm. The measurement results show that the ZG-20 NPs possess an excellent selectivity, i.e., the NPs only respond to various thiol compounds but not to the non-thiolated amino acids (Figure 3A). Similarly, the selectivity experiments of the naked PySSCou molecule with these amino acids and thiol compounds also show the same trend, thereby confirming that the integration of PySSCou into the polymeric NPs did not compromise its selectivity (Figure S5 in the SI).


"Turn-on" fluorescence probe integrated polymer nanoparticles for sensing biological thiol molecules.

Ang CY, Tan SY, Lu Y, Bai L, Li M, Li P, Zhang Q, Selvan ST, Zhao Y - Sci Rep (2014)

(A) Fluorescence intensity (λ = 477 nm) of ZG-20 NPs after overnight co-incubation with various amino acids and thiol compounds (5.0 mM) in PBS (pH = 7.4) at 37°C (λex = 330 nm). Error bar: n = 3. Inset: Fluorescence images of the resulted NP solutions under UV lamp. From bottom left to top right: ZG-20 NPs treated with DTT, Cys, Hcy, GSH, Methionine (Met), Alanine (Ala), Glycine (Gly), Leucine (Leu), Histidine (His), Isoleucine (Ile), Tryptophan (Trp), Tyrosine (Tyr), Aspartic acid (Asp), Arginine (Arg), Asparagine (Asn), Lysine (Lys), Phenylalanine (Phe), Threonine (Thr), Proline (Pro), Serine (Ser), Valine (Val), Glutamine (Gln) and Glutamic acid (Glu). (B) Fluorescence spectra of the NP solution after overnight co-incubation with various concentrations of Cys in PBS (pH = 7.4) at 37°C.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4231329&req=5

f3: (A) Fluorescence intensity (λ = 477 nm) of ZG-20 NPs after overnight co-incubation with various amino acids and thiol compounds (5.0 mM) in PBS (pH = 7.4) at 37°C (λex = 330 nm). Error bar: n = 3. Inset: Fluorescence images of the resulted NP solutions under UV lamp. From bottom left to top right: ZG-20 NPs treated with DTT, Cys, Hcy, GSH, Methionine (Met), Alanine (Ala), Glycine (Gly), Leucine (Leu), Histidine (His), Isoleucine (Ile), Tryptophan (Trp), Tyrosine (Tyr), Aspartic acid (Asp), Arginine (Arg), Asparagine (Asn), Lysine (Lys), Phenylalanine (Phe), Threonine (Thr), Proline (Pro), Serine (Ser), Valine (Val), Glutamine (Gln) and Glutamic acid (Glu). (B) Fluorescence spectra of the NP solution after overnight co-incubation with various concentrations of Cys in PBS (pH = 7.4) at 37°C.
Mentions: The detection selectivity of probe-integrated ZG-20 NPs was evaluated by conducting the co-incubation of the NPs (0.66 mg mL−1) with various amino acids and thiol compounds (5.0 mM) in PBS buffer overnight. In this study, we used dithiolthretol (DTT) to investigate the response of the NP system. Although DTT is not considered as a biological thiol compound, it is a well-known thiolated reducing agent and could serve as a positive control for comparison. After the overnight incubation, we measured the fluorescence intensity of the NP solution at 477 nm under the excitation wavelength of 330 nm. The measurement results show that the ZG-20 NPs possess an excellent selectivity, i.e., the NPs only respond to various thiol compounds but not to the non-thiolated amino acids (Figure 3A). Similarly, the selectivity experiments of the naked PySSCou molecule with these amino acids and thiol compounds also show the same trend, thereby confirming that the integration of PySSCou into the polymeric NPs did not compromise its selectivity (Figure S5 in the SI).

Bottom Line: Configuration interaction singles (CIS) calculation was performed to confirm the mechanism of this process.A series of sensing studies were carried out, showing that the probe-integrated nanoparticles were highly selective towards biological thiol compounds over non-thiolated amino acids.This development paves a path for the sensing and detection of biological thiols, serving as a potential diagnostic tool in the future.

View Article: PubMed Central - PubMed

Affiliation: Division of Chemistry and Biological Chemistry, Nanyang Technological University, 21 Nanyang Link, Singapore 637371, Singapore.

ABSTRACT
A "turn-on" thiol-responsive fluorescence probe was synthesized and integrated into polymeric nanoparticles for sensing intracellular thiols. There is a photo-induced electron transfer process in the off state of the probe, and this process is terminated upon the reaction with thiol compounds. Configuration interaction singles (CIS) calculation was performed to confirm the mechanism of this process. A series of sensing studies were carried out, showing that the probe-integrated nanoparticles were highly selective towards biological thiol compounds over non-thiolated amino acids. Kinetic studies were also performed to investigate the relative reaction rate between the probe and the thiolated amino acids. Subsequently, the Gibbs free energy of the reactions was explored by means of the electrochemical method. Finally, the detection system was employed for sensing intracellular thiols in cancer cells, and the sensing selectivity could be further enhanced with the use of a cancer cell-targeting ligand in the nanoparticles. This development paves a path for the sensing and detection of biological thiols, serving as a potential diagnostic tool in the future.

Show MeSH
Related in: MedlinePlus