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Modulation of Silica Nanoparticle Uptake into Human Osteoblast Cells by Variation of the Ratio of Amino and Sulfonate Surface Groups: Effects of Serum.

Shahabi S, Treccani L, Dringen R, Rezwan K - ACS Appl Mater Interfaces (2015)

Bottom Line: Irrespective of the original surface charge, serum proteins adsorbed onto the surface, neutralized the zeta potential values, and prevented the aggregation of the tailor-made FFSNPs.In contrast, in serum-containing medium, anionic FFSNPs were internalized by HOB cells more strongly, despite the similar size and surface charge of all types of protein-covered FFSNPs.Thus, at physiological condition, when the presence of proteins is inevitable, sulfonate-functionalized silica NPs are the favorite choice to achieve a desired high rate of NP internalization.

View Article: PubMed Central - PubMed

Affiliation: †Advanced Ceramics, University of Bremen, Am Biologischen Garten 2, 28359 Bremen, Germany.

ABSTRACT
To study the importance of the surface charge for cellular uptake of silica nanoparticles (NPs), we synthesized five different single- or multifunctionalized fluorescent silica NPs (FFSNPs) by introducing various ratios of amino and sulfonate groups into their surface. The zeta potential values of these FFSNPs were customized from highly positive to highly negative, while other physicochemical properties remained almost constant. Irrespective of the original surface charge, serum proteins adsorbed onto the surface, neutralized the zeta potential values, and prevented the aggregation of the tailor-made FFSNPs. Depending on the surface charge and on the absence or presence of serum, two opposite trends were found concerning the cellular uptake of FFSNPs. In the absence of serum, positively charged NPs were more strongly accumulated by human osteoblast (HOB) cells than negatively charged NPs. In contrast, in serum-containing medium, anionic FFSNPs were internalized by HOB cells more strongly, despite the similar size and surface charge of all types of protein-covered FFSNPs. Thus, at physiological condition, when the presence of proteins is inevitable, sulfonate-functionalized silica NPs are the favorite choice to achieve a desired high rate of NP internalization.

No MeSH data available.


Related in: MedlinePlus

Physicochemical properties of FFSNPs indifferent media. The zeta potential (a) of FFSNPs in the given mediawas measured 0.5 h after preparation. Panel (b) shows the amount ofadsorbed BSA (normalized to the specific surface area) determinedfor FFSNPs which had been dispersed in H2O containing 1%BSA for 0.5, 2, 4, or 6 h at 37 °C. Panels (c–f) showthe average hydrodynamic diameters of FFSNPs as a function of timein the indicated media, demonstrating colloidal stability or instability.In (b), asterisks (∗) show a significant difference in BSAadsorption (p < 0.05) for each particle betweendifferent incubation times. Sedimentation or severe aggregation ofFFSNPs, corresponding to DH larger than550 nm or PDI > 0.3, are indicated by X in panels (c, e).
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fig2: Physicochemical properties of FFSNPs indifferent media. The zeta potential (a) of FFSNPs in the given mediawas measured 0.5 h after preparation. Panel (b) shows the amount ofadsorbed BSA (normalized to the specific surface area) determinedfor FFSNPs which had been dispersed in H2O containing 1%BSA for 0.5, 2, 4, or 6 h at 37 °C. Panels (c–f) showthe average hydrodynamic diameters of FFSNPs as a function of timein the indicated media, demonstrating colloidal stability or instability.In (b), asterisks (∗) show a significant difference in BSAadsorption (p < 0.05) for each particle betweendifferent incubation times. Sedimentation or severe aggregation ofFFSNPs, corresponding to DH larger than550 nm or PDI > 0.3, are indicated by X in panels (c, e).

Mentions: The zeta potential values of thesynthesized FFSNPs in aqueous dispersions varied greatly over a broadrange from 33.4 ± 4.5 to −53.7 ± 3.5 mV (Figure 2a). By variation of the surface charge via single-and multifunctionalization, two cationic (100A and 75A + 25H), onealmost neutral (50A + 50H), and two anionic silica NPs (25A + 75Hand 100H) were synthesized. An analogous variation of surface chargewas observed for the FFSNP dispersions prepared in DMEM + AB/AM (1%)which ranged between 23.2 ± 2.9 and −25.4 ± 3.8 mV.DMEM supplemented with 10% FCS is commonly used as a cell culturemedium for in vitro studies. Therefore, the zeta potentials of FFSNPswere also measured for dispersions in DMEM + FCS (10%) + AB/AM (1%).In serum-containing medium, all the FFSNPs had acquired a negativelycharged surface (−12.5 ± 3.5 to −18.8 ± 3.4mV). Due to the complexity of serum-supplemented medium, we selectedBSA as a model protein and measured zeta potential of FFSNPs in H2O + BSA (1%), as BSA is the most abundant protein found inplasma and in NP protein corona.35,36 The concentrationof BSA (1%) was chosen, as it is equivalent to the total protein concentrationpresent in the 10% FCS.37 Negative zetapotential values (−21.3 ± 1.6 to −27.9 ± 2.8mV) were obtained from FFSNP dispersions prepared in H2O + BSA (1%), regardless of the original surface charges of the NPs.


Modulation of Silica Nanoparticle Uptake into Human Osteoblast Cells by Variation of the Ratio of Amino and Sulfonate Surface Groups: Effects of Serum.

Shahabi S, Treccani L, Dringen R, Rezwan K - ACS Appl Mater Interfaces (2015)

Physicochemical properties of FFSNPs indifferent media. The zeta potential (a) of FFSNPs in the given mediawas measured 0.5 h after preparation. Panel (b) shows the amount ofadsorbed BSA (normalized to the specific surface area) determinedfor FFSNPs which had been dispersed in H2O containing 1%BSA for 0.5, 2, 4, or 6 h at 37 °C. Panels (c–f) showthe average hydrodynamic diameters of FFSNPs as a function of timein the indicated media, demonstrating colloidal stability or instability.In (b), asterisks (∗) show a significant difference in BSAadsorption (p < 0.05) for each particle betweendifferent incubation times. Sedimentation or severe aggregation ofFFSNPs, corresponding to DH larger than550 nm or PDI > 0.3, are indicated by X in panels (c, e).
© Copyright Policy - editor-choice
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4490775&req=5

fig2: Physicochemical properties of FFSNPs indifferent media. The zeta potential (a) of FFSNPs in the given mediawas measured 0.5 h after preparation. Panel (b) shows the amount ofadsorbed BSA (normalized to the specific surface area) determinedfor FFSNPs which had been dispersed in H2O containing 1%BSA for 0.5, 2, 4, or 6 h at 37 °C. Panels (c–f) showthe average hydrodynamic diameters of FFSNPs as a function of timein the indicated media, demonstrating colloidal stability or instability.In (b), asterisks (∗) show a significant difference in BSAadsorption (p < 0.05) for each particle betweendifferent incubation times. Sedimentation or severe aggregation ofFFSNPs, corresponding to DH larger than550 nm or PDI > 0.3, are indicated by X in panels (c, e).
Mentions: The zeta potential values of thesynthesized FFSNPs in aqueous dispersions varied greatly over a broadrange from 33.4 ± 4.5 to −53.7 ± 3.5 mV (Figure 2a). By variation of the surface charge via single-and multifunctionalization, two cationic (100A and 75A + 25H), onealmost neutral (50A + 50H), and two anionic silica NPs (25A + 75Hand 100H) were synthesized. An analogous variation of surface chargewas observed for the FFSNP dispersions prepared in DMEM + AB/AM (1%)which ranged between 23.2 ± 2.9 and −25.4 ± 3.8 mV.DMEM supplemented with 10% FCS is commonly used as a cell culturemedium for in vitro studies. Therefore, the zeta potentials of FFSNPswere also measured for dispersions in DMEM + FCS (10%) + AB/AM (1%).In serum-containing medium, all the FFSNPs had acquired a negativelycharged surface (−12.5 ± 3.5 to −18.8 ± 3.4mV). Due to the complexity of serum-supplemented medium, we selectedBSA as a model protein and measured zeta potential of FFSNPs in H2O + BSA (1%), as BSA is the most abundant protein found inplasma and in NP protein corona.35,36 The concentrationof BSA (1%) was chosen, as it is equivalent to the total protein concentrationpresent in the 10% FCS.37 Negative zetapotential values (−21.3 ± 1.6 to −27.9 ± 2.8mV) were obtained from FFSNP dispersions prepared in H2O + BSA (1%), regardless of the original surface charges of the NPs.

Bottom Line: Irrespective of the original surface charge, serum proteins adsorbed onto the surface, neutralized the zeta potential values, and prevented the aggregation of the tailor-made FFSNPs.In contrast, in serum-containing medium, anionic FFSNPs were internalized by HOB cells more strongly, despite the similar size and surface charge of all types of protein-covered FFSNPs.Thus, at physiological condition, when the presence of proteins is inevitable, sulfonate-functionalized silica NPs are the favorite choice to achieve a desired high rate of NP internalization.

View Article: PubMed Central - PubMed

Affiliation: †Advanced Ceramics, University of Bremen, Am Biologischen Garten 2, 28359 Bremen, Germany.

ABSTRACT
To study the importance of the surface charge for cellular uptake of silica nanoparticles (NPs), we synthesized five different single- or multifunctionalized fluorescent silica NPs (FFSNPs) by introducing various ratios of amino and sulfonate groups into their surface. The zeta potential values of these FFSNPs were customized from highly positive to highly negative, while other physicochemical properties remained almost constant. Irrespective of the original surface charge, serum proteins adsorbed onto the surface, neutralized the zeta potential values, and prevented the aggregation of the tailor-made FFSNPs. Depending on the surface charge and on the absence or presence of serum, two opposite trends were found concerning the cellular uptake of FFSNPs. In the absence of serum, positively charged NPs were more strongly accumulated by human osteoblast (HOB) cells than negatively charged NPs. In contrast, in serum-containing medium, anionic FFSNPs were internalized by HOB cells more strongly, despite the similar size and surface charge of all types of protein-covered FFSNPs. Thus, at physiological condition, when the presence of proteins is inevitable, sulfonate-functionalized silica NPs are the favorite choice to achieve a desired high rate of NP internalization.

No MeSH data available.


Related in: MedlinePlus