Limits...
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.


Related in: MedlinePlus

Amination control(a). Representative NP dissolution NMR corresponding to chosen amine surface densities labelled H, M, L and VL (b). Ninhydrin assay measurement of no. of surface amines across precursor concentration range in optimal amination conditions (“natural” pH with thermal treatment). Red stars indicate the chosen surface densities with corresponding NMR surface measurements (All Ninhydrin and NMR averaged from minimum of three independently synthesized batches) (c). Representative zeta potential–pH titrations for chosen surface densities.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4664868&req=5

f1: Amination control(a). Representative NP dissolution NMR corresponding to chosen amine surface densities labelled H, M, L and VL (b). Ninhydrin assay measurement of no. of surface amines across precursor concentration range in optimal amination conditions (“natural” pH with thermal treatment). Red stars indicate the chosen surface densities with corresponding NMR surface measurements (All Ninhydrin and NMR averaged from minimum of three independently synthesized batches) (c). Representative zeta potential–pH titrations for chosen surface densities.

Mentions: Aminopropyltrimethoxysilane (APTS) was surface condensed from well – mixed aqueous mixtures5 (see Fig. S1) varying the reaction concentration used to control the final amine surface density. Multiple batches of amino functionalized nanoparticles were thus synthesized and studied using a modified ninhydrin assay6 and zeta potential/pH titrations (see Fig. 1b,c, also methods section S3). Some such assays, in our studies of nanoparticle surfaces, proved variable and irreproducible, depending on the specific method chosen, and we caution against their use, unchecked, in general. While we have been able to adapt the Ninhydrin assay (see also Fig. S2) to obtain variations of less than 10% assay to assay, an independent quantitative measure of ligand density remains necessary. Using solution proton nuclear magnetic resonance (NMR) on the intact nanoparticles monodispersed in D2O, at sufficient NP concentration (1% w/w for 50 nm), one can detect the relaxation of the propyl chain (C-H) protons of bound APTS (Fig. 1), but the signals are low and broadened. Silica solubility is known to rapidly increase above pH 1178. Accordingly, addition of aliquots of sodium deuteroxide solution (NaOD) to the aforementioned samples resulted in the solubilisation of the silica nanoparticle cores (Fig. S3 and S4), and release of the surface ligands. The resultant increase and narrowing in the corresponding NMR signals permitted peak integration of the ligand protons and, referencing to a calibration curve (normalized by internal standard) (Fig. S5) for fixed acquisition times, a direct measure of the amine surface density. The results were found to be in good agreement with (modified) Ninhydrin studies (Fig. 1b). Four representative amine densities, nominally high, medium, low and very low (H, M, L and VL) corresponding to mean densities of 8, 5.9, 2.5 and 0.8 NH2 groups per nm2 (measured by ninhydrin assay and averaged from 9 individual batches), were chosen as representative candidates for further investigation. Reproducibility was emphasized through the careful control of synthetic parameters and was monitored through consistent investigation of batch –to – batch variations (Fig. S6 for sample batch results), which were found to be quite modest, while efficiency of purification was also monitored by NMR (Fig. S7). In our experience, these silica scaffold particles are amongst the most reproducibly synthesized and characterized of their type, and their study, across multiple batches, reveals subtle roles of surface architecture in biological interactions.


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)

Amination control(a). Representative NP dissolution NMR corresponding to chosen amine surface densities labelled H, M, L and VL (b). Ninhydrin assay measurement of no. of surface amines across precursor concentration range in optimal amination conditions (“natural” pH with thermal treatment). Red stars indicate the chosen surface densities with corresponding NMR surface measurements (All Ninhydrin and NMR averaged from minimum of three independently synthesized batches) (c). Representative zeta potential–pH titrations for chosen surface densities.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

f1: Amination control(a). Representative NP dissolution NMR corresponding to chosen amine surface densities labelled H, M, L and VL (b). Ninhydrin assay measurement of no. of surface amines across precursor concentration range in optimal amination conditions (“natural” pH with thermal treatment). Red stars indicate the chosen surface densities with corresponding NMR surface measurements (All Ninhydrin and NMR averaged from minimum of three independently synthesized batches) (c). Representative zeta potential–pH titrations for chosen surface densities.
Mentions: Aminopropyltrimethoxysilane (APTS) was surface condensed from well – mixed aqueous mixtures5 (see Fig. S1) varying the reaction concentration used to control the final amine surface density. Multiple batches of amino functionalized nanoparticles were thus synthesized and studied using a modified ninhydrin assay6 and zeta potential/pH titrations (see Fig. 1b,c, also methods section S3). Some such assays, in our studies of nanoparticle surfaces, proved variable and irreproducible, depending on the specific method chosen, and we caution against their use, unchecked, in general. While we have been able to adapt the Ninhydrin assay (see also Fig. S2) to obtain variations of less than 10% assay to assay, an independent quantitative measure of ligand density remains necessary. Using solution proton nuclear magnetic resonance (NMR) on the intact nanoparticles monodispersed in D2O, at sufficient NP concentration (1% w/w for 50 nm), one can detect the relaxation of the propyl chain (C-H) protons of bound APTS (Fig. 1), but the signals are low and broadened. Silica solubility is known to rapidly increase above pH 1178. Accordingly, addition of aliquots of sodium deuteroxide solution (NaOD) to the aforementioned samples resulted in the solubilisation of the silica nanoparticle cores (Fig. S3 and S4), and release of the surface ligands. The resultant increase and narrowing in the corresponding NMR signals permitted peak integration of the ligand protons and, referencing to a calibration curve (normalized by internal standard) (Fig. S5) for fixed acquisition times, a direct measure of the amine surface density. The results were found to be in good agreement with (modified) Ninhydrin studies (Fig. 1b). Four representative amine densities, nominally high, medium, low and very low (H, M, L and VL) corresponding to mean densities of 8, 5.9, 2.5 and 0.8 NH2 groups per nm2 (measured by ninhydrin assay and averaged from 9 individual batches), were chosen as representative candidates for further investigation. Reproducibility was emphasized through the careful control of synthetic parameters and was monitored through consistent investigation of batch –to – batch variations (Fig. S6 for sample batch results), which were found to be quite modest, while efficiency of purification was also monitored by NMR (Fig. S7). In our experience, these silica scaffold particles are amongst the most reproducibly synthesized and characterized of their type, and their study, across multiple batches, reveals subtle roles of surface architecture in biological interactions.

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.


Related in: MedlinePlus