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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

Uptake of FFSNPs (100 μg/mL) into HOB cells after a 2 h exposureat 4 or 37 °C in the absence or at 37 °C in the presenceof the endocytosis inhibitors, chlorpromazine (30 μM), wortmannin(300 nM), or nystatin (10 μM) in serum-free (a) or serum-containingmedium (b). The amount of cellular particles was quantified by fluorimetryof cell pellets. The data are expressed as means ± SD of threeindependent experiments and are given as a percentage of the respectiveFFSNP-treated cells incubated at 37 °C in the presence of theappropriate concentration of DMSO which was used as solvent for theinhibitors. Significant differences between the obtained values andthe control are indicated (∗, p < 0.05;§, p < 0.01; #, p < 0.001).
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fig6: Uptake of FFSNPs (100 μg/mL) into HOB cells after a 2 h exposureat 4 or 37 °C in the absence or at 37 °C in the presenceof the endocytosis inhibitors, chlorpromazine (30 μM), wortmannin(300 nM), or nystatin (10 μM) in serum-free (a) or serum-containingmedium (b). The amount of cellular particles was quantified by fluorimetryof cell pellets. The data are expressed as means ± SD of threeindependent experiments and are given as a percentage of the respectiveFFSNP-treated cells incubated at 37 °C in the presence of theappropriate concentration of DMSO which was used as solvent for theinhibitors. Significant differences between the obtained values andthe control are indicated (∗, p < 0.05;§, p < 0.01; #, p < 0.001).

Mentions: In order to analyze the mechanism of cellular uptakeof FFSNPs into HOB, inhibitors of different endocytotic pathways wereapplied (Figure 6). The inhibitor concentrationsused were defined in preliminary experiments and represent the highestconcentrations which did not significantly compromise cell viabilitywithin a 2 h treatment in both serum-free and serum-containing medium(data not shown). Incubation of HOB cells at 4 °C neither alteredWST-1 reduction capacity nor led to higher LDH leakage compared tocontrols (data not shown) but drastically prevented the cellular accumulationof FFSNPs (Figure 6). In the presence of chlorpromazine,a specific clathrin-mediated endocytosis inhibitor,38 the cellular uptake of all FFSNPs was lowered in comparisonto the respective controls independent of the type of medium applied.However, in the presence of serum, the inhibitory effect of chlorpromazineon cellular uptake was stronger for anionic FFSNP (p < 0.01) in comparison to cationic and neutral FFSNPs (p < 0.05). When HOB cells were exposed to wortmannin,a macropinocytosis inhibitor,38 no inhibitoryeffect on the uptake of FFSNPs was observed in serum-free medium,while the cellular accumulation of FFSNPs was lowered in the presenceof wortmannin in serum-containing medium. In contrast, nystatin, aninhibitor of caveolin-dependent endocytosis,38 did not affect the uptake of FFSNPs (Figure 6).


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)

Uptake of FFSNPs (100 μg/mL) into HOB cells after a 2 h exposureat 4 or 37 °C in the absence or at 37 °C in the presenceof the endocytosis inhibitors, chlorpromazine (30 μM), wortmannin(300 nM), or nystatin (10 μM) in serum-free (a) or serum-containingmedium (b). The amount of cellular particles was quantified by fluorimetryof cell pellets. The data are expressed as means ± SD of threeindependent experiments and are given as a percentage of the respectiveFFSNP-treated cells incubated at 37 °C in the presence of theappropriate concentration of DMSO which was used as solvent for theinhibitors. Significant differences between the obtained values andthe control are indicated (∗, p < 0.05;§, p < 0.01; #, p < 0.001).
© Copyright Policy - editor-choice
Related In: Results  -  Collection

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

fig6: Uptake of FFSNPs (100 μg/mL) into HOB cells after a 2 h exposureat 4 or 37 °C in the absence or at 37 °C in the presenceof the endocytosis inhibitors, chlorpromazine (30 μM), wortmannin(300 nM), or nystatin (10 μM) in serum-free (a) or serum-containingmedium (b). The amount of cellular particles was quantified by fluorimetryof cell pellets. The data are expressed as means ± SD of threeindependent experiments and are given as a percentage of the respectiveFFSNP-treated cells incubated at 37 °C in the presence of theappropriate concentration of DMSO which was used as solvent for theinhibitors. Significant differences between the obtained values andthe control are indicated (∗, p < 0.05;§, p < 0.01; #, p < 0.001).
Mentions: In order to analyze the mechanism of cellular uptakeof FFSNPs into HOB, inhibitors of different endocytotic pathways wereapplied (Figure 6). The inhibitor concentrationsused were defined in preliminary experiments and represent the highestconcentrations which did not significantly compromise cell viabilitywithin a 2 h treatment in both serum-free and serum-containing medium(data not shown). Incubation of HOB cells at 4 °C neither alteredWST-1 reduction capacity nor led to higher LDH leakage compared tocontrols (data not shown) but drastically prevented the cellular accumulationof FFSNPs (Figure 6). In the presence of chlorpromazine,a specific clathrin-mediated endocytosis inhibitor,38 the cellular uptake of all FFSNPs was lowered in comparisonto the respective controls independent of the type of medium applied.However, in the presence of serum, the inhibitory effect of chlorpromazineon cellular uptake was stronger for anionic FFSNP (p < 0.01) in comparison to cationic and neutral FFSNPs (p < 0.05). When HOB cells were exposed to wortmannin,a macropinocytosis inhibitor,38 no inhibitoryeffect on the uptake of FFSNPs was observed in serum-free medium,while the cellular accumulation of FFSNPs was lowered in the presenceof wortmannin in serum-containing medium. In contrast, nystatin, aninhibitor of caveolin-dependent endocytosis,38 did not affect the uptake of FFSNPs (Figure 6).

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