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Tuning of nanoparticle biological functionality through controlled surface chemistry and characterisation at the bioconjugated nanoparticle surface.

Hristov DR, Rocks L, Kelly PM, Thomas SS, Pitek AS, Verderio P, Mahon E, Dawson KA - Sci Rep (2015)

Bottom Line: We have used a silica - PEG based bionanoconjugate synthetic scheme to study the subtle connection between cell receptor specific recognition and architecture of surface functionalization chemistry.Extensive physicochemical characterization of the grafted architecture is capable of capturing significant levels of detail of both the linker and grafted organization, allowing for improved reproducibility and ultimately insight into biological functionality.Our data suggest that scaffold details, propagating PEG layer architecture effects, determine not only the rate of uptake of conjugated nanoparticles into cells but also, more significantly, the specificity of pathways via which uptake occurs.

View Article: PubMed Central - PubMed

Affiliation: Centre for BioNano Interactions, School of Chemistry and Chemical Biology, University College Dublin, Belfield, Dublin 4, Ireland.

ABSTRACT
We have used a silica - PEG based bionanoconjugate synthetic scheme to study the subtle connection between cell receptor specific recognition and architecture of surface functionalization chemistry. Extensive physicochemical characterization of the grafted architecture is capable of capturing significant levels of detail of both the linker and grafted organization, allowing for improved reproducibility and ultimately insight into biological functionality. Our data suggest that scaffold details, propagating PEG layer architecture effects, determine not only the rate of uptake of conjugated nanoparticles into cells but also, more significantly, the specificity of pathways via which uptake occurs.

No MeSH data available.


Functionality control by varying surface amine density(a). NMR of PEGylated H, M, L and VL nanoparticles before and after dissolution with all intensities normalized against an internal standard. (b). Comparison of SM(PEG)8 determination by NMR and TGA with amine density in background (grey) for series H, M, L, VL. (c). Representative TGA data for NP set. (d). Table 1.
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f2: Functionality control by varying surface amine density(a). NMR of PEGylated H, M, L and VL nanoparticles before and after dissolution with all intensities normalized against an internal standard. (b). Comparison of SM(PEG)8 determination by NMR and TGA with amine density in background (grey) for series H, M, L, VL. (c). Representative TGA data for NP set. (d). Table 1.

Mentions: In the same way, NMR (Fig. S8 for assigned spectra) was then applied in the determination of surface ligand concentrations for subsequent conjugation steps, and proved the most powerful of the range of complimentary methods used in the study of SM(PEG)8 coupling to amine presenting NPs. For the aminated nanoparticles (H, M, L and VL), reactive SM(PEG)8 linker concentrations were varied, with products then purified by centrifugation (Fig. S9). Ligand surface densities were investigated indirectly by Ninhydrin assay (monitoring residual reactive amine) and directly by dissolution NMR (Fig. S10) and thermogravimetric analysis (TGA). Thus, PEGylation was quantified by proton NMR (Fig. 2a,b, Table 1 and Fig. S9 for details) using the ethylene protons from 3.64 – 3.7 ppm after NP dissolution. TGA was used as a complimentary method (Fig. S11) which allowed for the determination of relative amounts of the ligands with results in fair agreement with those of NMR (see Table 1). The Ninhydrin assay, applied post – PEGylation, appears to under – detect unreacted amine groups (when compared to NMR) which we attribute to limitations in surface accessibility of the Ninhydrin reagent to the PEGylated surface (Fig. S12). PEG surface coverage was interpreted though dispersion stability studies using dynamic light scattering (DLS), differential centrifugal sedimentation (DCS) and serum binding resistance investigations (SDS – PAGE). In all cases the starting amine nanoparticles were highly unstable, agglomerating immediately in phosphate buffered saline (PBS). We studied varying surface PEG concentration equivalents against each amine density and found that higher levels of PEGylation, as could be expected, result in an increase in stability against agglomeration in PBS (Figs S13 and S14 for transmission electron microscopy – TEM). Additionally protein adsorption studies, using serum incubation, were used as a probe for surface coverage and showed, as expected, a reduction in protein adsorption levels for increased SM(PEG)8 densities (see Fig. S12d)91011.


Tuning of nanoparticle biological functionality through controlled surface chemistry and characterisation at the bioconjugated nanoparticle surface.

Hristov DR, Rocks L, Kelly PM, Thomas SS, Pitek AS, Verderio P, Mahon E, Dawson KA - Sci Rep (2015)

Functionality control by varying surface amine density(a). NMR of PEGylated H, M, L and VL nanoparticles before and after dissolution with all intensities normalized against an internal standard. (b). Comparison of SM(PEG)8 determination by NMR and TGA with amine density in background (grey) for series H, M, L, VL. (c). Representative TGA data for NP set. (d). Table 1.
© Copyright Policy - open-access
Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC4664868&req=5

f2: Functionality control by varying surface amine density(a). NMR of PEGylated H, M, L and VL nanoparticles before and after dissolution with all intensities normalized against an internal standard. (b). Comparison of SM(PEG)8 determination by NMR and TGA with amine density in background (grey) for series H, M, L, VL. (c). Representative TGA data for NP set. (d). Table 1.
Mentions: In the same way, NMR (Fig. S8 for assigned spectra) was then applied in the determination of surface ligand concentrations for subsequent conjugation steps, and proved the most powerful of the range of complimentary methods used in the study of SM(PEG)8 coupling to amine presenting NPs. For the aminated nanoparticles (H, M, L and VL), reactive SM(PEG)8 linker concentrations were varied, with products then purified by centrifugation (Fig. S9). Ligand surface densities were investigated indirectly by Ninhydrin assay (monitoring residual reactive amine) and directly by dissolution NMR (Fig. S10) and thermogravimetric analysis (TGA). Thus, PEGylation was quantified by proton NMR (Fig. 2a,b, Table 1 and Fig. S9 for details) using the ethylene protons from 3.64 – 3.7 ppm after NP dissolution. TGA was used as a complimentary method (Fig. S11) which allowed for the determination of relative amounts of the ligands with results in fair agreement with those of NMR (see Table 1). The Ninhydrin assay, applied post – PEGylation, appears to under – detect unreacted amine groups (when compared to NMR) which we attribute to limitations in surface accessibility of the Ninhydrin reagent to the PEGylated surface (Fig. S12). PEG surface coverage was interpreted though dispersion stability studies using dynamic light scattering (DLS), differential centrifugal sedimentation (DCS) and serum binding resistance investigations (SDS – PAGE). In all cases the starting amine nanoparticles were highly unstable, agglomerating immediately in phosphate buffered saline (PBS). We studied varying surface PEG concentration equivalents against each amine density and found that higher levels of PEGylation, as could be expected, result in an increase in stability against agglomeration in PBS (Figs S13 and S14 for transmission electron microscopy – TEM). Additionally protein adsorption studies, using serum incubation, were used as a probe for surface coverage and showed, as expected, a reduction in protein adsorption levels for increased SM(PEG)8 densities (see Fig. S12d)91011.

Bottom Line: We have used a silica - PEG based bionanoconjugate synthetic scheme to study the subtle connection between cell receptor specific recognition and architecture of surface functionalization chemistry.Extensive physicochemical characterization of the grafted architecture is capable of capturing significant levels of detail of both the linker and grafted organization, allowing for improved reproducibility and ultimately insight into biological functionality.Our data suggest that scaffold details, propagating PEG layer architecture effects, determine not only the rate of uptake of conjugated nanoparticles into cells but also, more significantly, the specificity of pathways via which uptake occurs.

View Article: PubMed Central - PubMed

Affiliation: Centre for BioNano Interactions, School of Chemistry and Chemical Biology, University College Dublin, Belfield, Dublin 4, Ireland.

ABSTRACT
We have used a silica - PEG based bionanoconjugate synthetic scheme to study the subtle connection between cell receptor specific recognition and architecture of surface functionalization chemistry. Extensive physicochemical characterization of the grafted architecture is capable of capturing significant levels of detail of both the linker and grafted organization, allowing for improved reproducibility and ultimately insight into biological functionality. Our data suggest that scaffold details, propagating PEG layer architecture effects, determine not only the rate of uptake of conjugated nanoparticles into cells but also, more significantly, the specificity of pathways via which uptake occurs.

No MeSH data available.