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Preparation and tumor cell model based biobehavioral evaluation of the nanocarrier system using partially reduced graphene oxide functionalized by surfactant.

Wang Y, Liu K, Luo Z, Duan Y - Int J Nanomedicine (2015)

Bottom Line: The partially reduced graphene oxide sheets functionalized by surfactant exhibit good dispersibility.The complexes of PSSG-EPI can be transferred to lysosomes in 2 hours through endocytosis, then the drug is released in the cytoplasm in 8 hours, and ultimately EPI is delivered into cell nucleus to exhibit medicinal effects in 1 day.The comprehensive exploration of the biological uptake mechanism of functional graphene-mediated tumor cell targeting model provides a typical protocol for evaluation of drug delivery system and will benefit the discovery of new surfactant-modified nanocarriers in nanomedicine.

View Article: PubMed Central - PubMed

Affiliation: Research Center of Analytical Instrumentation, Key Laboratory of Bio-resource and Eco-environment, Ministry of Education, College of Life Science, Sichuan University, Chengdu, People's Republic of China.

ABSTRACT

Background: Currently, surfactant-functionalized nanomaterials are tending toward development of novel tumor-targeted drug carriers to overcome multidrug resistance in cancer therapy. Now, investigating the biocompatibility and uptake mechanism of specific drug delivery systems is a growing trend, but usually a troublesome issue, in simple pharmaceutical research.

Methods: We first reported the partially reduced graphene oxide modified with poly(sodium 4-styrenesulfonate) (PSS) as a nanocarrier system. Then, the nanocarrier was characterized by atomic force microscope, scanning electron microscope, high-resolution transmission electron microscope, ultraviolet-visible (UV-vis) spectroscopy, Fourier transform infrared spectroscopy, X-Ray powder diffraction, and Raman spectroscopy. Epirubicin (EPI) was attached to PSSG via π-π stacking, hydrogen bonding, and physical absorption to form conjugates of PSSG-EPI. The adsorption and desorption profiles, cytotoxicity coupled with drug accumulation, and uptake of PSSG and PSSG-EPI were evaluated. Finally, the subcellular behaviors, distribution, and biological fate of the drug delivery system were explored by confocal laser scanning microscope using direct fluorescence colocalization imaging and transmission electron microscopy.

Results: The partially reduced graphene oxide sheets functionalized by surfactant exhibit good dispersibility. Moreover, due to much less carboxyl groups retained on the edge of PSSG sheets, the nanocarriers exhibit biocompatibility in vitro. The obtained PSSG shows a high drug-loading capacity of 2.22 mg/mg. The complexes of PSSG-EPI can be transferred to lysosomes in 2 hours through endocytosis, then the drug is released in the cytoplasm in 8 hours, and ultimately EPI is delivered into cell nucleus to exhibit medicinal effects in 1 day.

Conclusion: The comprehensive exploration of the biological uptake mechanism of functional graphene-mediated tumor cell targeting model provides a typical protocol for evaluation of drug delivery system and will benefit the discovery of new surfactant-modified nanocarriers in nanomedicine.

No MeSH data available.


Related in: MedlinePlus

Drug loading and controlled release.Notes: (A) Real time monitoring fluorescence spectra of the released free EPI in the supernatants after a sequentially increased volumes of 100 μg/mL PSSG (from a to k, 10, 30, 50, 70, 90, 110, 130, 150, 160, 170 and 180 μL, respectively), was added into 2 mL of 20 μg/mL EPI and incubated for 2 hours. Fluorescence spectra (B), and UV-Vis absorption spectra (C) of PSSG-EPI (20 μg/mL) after incubating in ethanol (a) and water (b) for 2 hours. Inserted graph in (C) shows the different colors of supernatants of PSSG-EPI released in ethanol (a) and water (b). (D) The relative released proportion of EPI from PSSG-EPI in different buffer solutions at pH 2.0 (a), pH 4.6 (b) and pH 7.4 (c). All data were normalized to the fluorescence intensity of EPI released from PSSG in ethanol under the same concentration.Abbreviations: PSSG, PSS-decorated nanographene; PSS, poly(sodium 4-styrenesulfonate); EPI, epirubicin.
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f4-ijn-10-4605: Drug loading and controlled release.Notes: (A) Real time monitoring fluorescence spectra of the released free EPI in the supernatants after a sequentially increased volumes of 100 μg/mL PSSG (from a to k, 10, 30, 50, 70, 90, 110, 130, 150, 160, 170 and 180 μL, respectively), was added into 2 mL of 20 μg/mL EPI and incubated for 2 hours. Fluorescence spectra (B), and UV-Vis absorption spectra (C) of PSSG-EPI (20 μg/mL) after incubating in ethanol (a) and water (b) for 2 hours. Inserted graph in (C) shows the different colors of supernatants of PSSG-EPI released in ethanol (a) and water (b). (D) The relative released proportion of EPI from PSSG-EPI in different buffer solutions at pH 2.0 (a), pH 4.6 (b) and pH 7.4 (c). All data were normalized to the fluorescence intensity of EPI released from PSSG in ethanol under the same concentration.Abbreviations: PSSG, PSS-decorated nanographene; PSS, poly(sodium 4-styrenesulfonate); EPI, epirubicin.

Mentions: The drug loading efficiency of PSSG was quantified by evaluating the concentration of free drug in the supernatants of PSSG–EPI according to the fluorescence intensity of EPI at 595 nm via an excitation wavelength at 488 nm. In Figure 4A, with the increased addition volumes (from a to k) of PSSG (100 μg/mL), the intensity of fluorescence emission peaks at 595 nm of the supernatants gradually decrease from 500 to below 50 and remain constant at the volume of 180 μL (curve k), which indicate that PSSG has reached its saturation adsorption value. Since 2 mL of 20 μg/mL EPI was exactly absorbed on 180 μL of 100 μg/mL PSSG, the MLC of PSSG to EPI can be calculated as the mass ratio of EPI to PSSG (40–18 μg). Therefore, for our drug carrier system, the MLC is 2.22 mg/mg, which is much higher than that of GO in the reported literatures (with corresponding values of 0.815,43 1,21 1.436 and 2 mg/mg,22 respectively). This is mainly due to the π–π stacking interaction between PSSG and EPI and sp2 hybridized structure of graphene nanosheets. Moreover, the hydrogen bonding interaction between the residual carboxyl groups on rGO and the sulfonic acid groups of PSS compromised the flexible polymer and the rigid nanosheets. In short, the polymer of PSS can supply more 2D aromatic planes to rGO, thus significantly enhancing its loading efficiency to aromatic drug molecules.21,44


Preparation and tumor cell model based biobehavioral evaluation of the nanocarrier system using partially reduced graphene oxide functionalized by surfactant.

Wang Y, Liu K, Luo Z, Duan Y - Int J Nanomedicine (2015)

Drug loading and controlled release.Notes: (A) Real time monitoring fluorescence spectra of the released free EPI in the supernatants after a sequentially increased volumes of 100 μg/mL PSSG (from a to k, 10, 30, 50, 70, 90, 110, 130, 150, 160, 170 and 180 μL, respectively), was added into 2 mL of 20 μg/mL EPI and incubated for 2 hours. Fluorescence spectra (B), and UV-Vis absorption spectra (C) of PSSG-EPI (20 μg/mL) after incubating in ethanol (a) and water (b) for 2 hours. Inserted graph in (C) shows the different colors of supernatants of PSSG-EPI released in ethanol (a) and water (b). (D) The relative released proportion of EPI from PSSG-EPI in different buffer solutions at pH 2.0 (a), pH 4.6 (b) and pH 7.4 (c). All data were normalized to the fluorescence intensity of EPI released from PSSG in ethanol under the same concentration.Abbreviations: PSSG, PSS-decorated nanographene; PSS, poly(sodium 4-styrenesulfonate); EPI, epirubicin.
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f4-ijn-10-4605: Drug loading and controlled release.Notes: (A) Real time monitoring fluorescence spectra of the released free EPI in the supernatants after a sequentially increased volumes of 100 μg/mL PSSG (from a to k, 10, 30, 50, 70, 90, 110, 130, 150, 160, 170 and 180 μL, respectively), was added into 2 mL of 20 μg/mL EPI and incubated for 2 hours. Fluorescence spectra (B), and UV-Vis absorption spectra (C) of PSSG-EPI (20 μg/mL) after incubating in ethanol (a) and water (b) for 2 hours. Inserted graph in (C) shows the different colors of supernatants of PSSG-EPI released in ethanol (a) and water (b). (D) The relative released proportion of EPI from PSSG-EPI in different buffer solutions at pH 2.0 (a), pH 4.6 (b) and pH 7.4 (c). All data were normalized to the fluorescence intensity of EPI released from PSSG in ethanol under the same concentration.Abbreviations: PSSG, PSS-decorated nanographene; PSS, poly(sodium 4-styrenesulfonate); EPI, epirubicin.
Mentions: The drug loading efficiency of PSSG was quantified by evaluating the concentration of free drug in the supernatants of PSSG–EPI according to the fluorescence intensity of EPI at 595 nm via an excitation wavelength at 488 nm. In Figure 4A, with the increased addition volumes (from a to k) of PSSG (100 μg/mL), the intensity of fluorescence emission peaks at 595 nm of the supernatants gradually decrease from 500 to below 50 and remain constant at the volume of 180 μL (curve k), which indicate that PSSG has reached its saturation adsorption value. Since 2 mL of 20 μg/mL EPI was exactly absorbed on 180 μL of 100 μg/mL PSSG, the MLC of PSSG to EPI can be calculated as the mass ratio of EPI to PSSG (40–18 μg). Therefore, for our drug carrier system, the MLC is 2.22 mg/mg, which is much higher than that of GO in the reported literatures (with corresponding values of 0.815,43 1,21 1.436 and 2 mg/mg,22 respectively). This is mainly due to the π–π stacking interaction between PSSG and EPI and sp2 hybridized structure of graphene nanosheets. Moreover, the hydrogen bonding interaction between the residual carboxyl groups on rGO and the sulfonic acid groups of PSS compromised the flexible polymer and the rigid nanosheets. In short, the polymer of PSS can supply more 2D aromatic planes to rGO, thus significantly enhancing its loading efficiency to aromatic drug molecules.21,44

Bottom Line: The partially reduced graphene oxide sheets functionalized by surfactant exhibit good dispersibility.The complexes of PSSG-EPI can be transferred to lysosomes in 2 hours through endocytosis, then the drug is released in the cytoplasm in 8 hours, and ultimately EPI is delivered into cell nucleus to exhibit medicinal effects in 1 day.The comprehensive exploration of the biological uptake mechanism of functional graphene-mediated tumor cell targeting model provides a typical protocol for evaluation of drug delivery system and will benefit the discovery of new surfactant-modified nanocarriers in nanomedicine.

View Article: PubMed Central - PubMed

Affiliation: Research Center of Analytical Instrumentation, Key Laboratory of Bio-resource and Eco-environment, Ministry of Education, College of Life Science, Sichuan University, Chengdu, People's Republic of China.

ABSTRACT

Background: Currently, surfactant-functionalized nanomaterials are tending toward development of novel tumor-targeted drug carriers to overcome multidrug resistance in cancer therapy. Now, investigating the biocompatibility and uptake mechanism of specific drug delivery systems is a growing trend, but usually a troublesome issue, in simple pharmaceutical research.

Methods: We first reported the partially reduced graphene oxide modified with poly(sodium 4-styrenesulfonate) (PSS) as a nanocarrier system. Then, the nanocarrier was characterized by atomic force microscope, scanning electron microscope, high-resolution transmission electron microscope, ultraviolet-visible (UV-vis) spectroscopy, Fourier transform infrared spectroscopy, X-Ray powder diffraction, and Raman spectroscopy. Epirubicin (EPI) was attached to PSSG via π-π stacking, hydrogen bonding, and physical absorption to form conjugates of PSSG-EPI. The adsorption and desorption profiles, cytotoxicity coupled with drug accumulation, and uptake of PSSG and PSSG-EPI were evaluated. Finally, the subcellular behaviors, distribution, and biological fate of the drug delivery system were explored by confocal laser scanning microscope using direct fluorescence colocalization imaging and transmission electron microscopy.

Results: The partially reduced graphene oxide sheets functionalized by surfactant exhibit good dispersibility. Moreover, due to much less carboxyl groups retained on the edge of PSSG sheets, the nanocarriers exhibit biocompatibility in vitro. The obtained PSSG shows a high drug-loading capacity of 2.22 mg/mg. The complexes of PSSG-EPI can be transferred to lysosomes in 2 hours through endocytosis, then the drug is released in the cytoplasm in 8 hours, and ultimately EPI is delivered into cell nucleus to exhibit medicinal effects in 1 day.

Conclusion: The comprehensive exploration of the biological uptake mechanism of functional graphene-mediated tumor cell targeting model provides a typical protocol for evaluation of drug delivery system and will benefit the discovery of new surfactant-modified nanocarriers in nanomedicine.

No MeSH data available.


Related in: MedlinePlus