Transfection System of Amino-Functionalized Calcium Phosphate Nanoparticles: In Vitro Efficacy, Biodegradability, and Immunogenicity Study

Abstract

Many methods have been developed in order to use calcium phosphate (CaP) for delivering nucleotides into living cells. Surface functionalization of CaP nanoparticles (CaP NPs) with N-(2-aminoethyl)-3-aminopropyltrimethoxysilane was shown recently to achieve dispersed NPs with a positive surface charge, capable of transfection (Chem. Mater. 2013, 25 (18), 3667). In this study, different crystal structures of amino-modified CaP NPs (brushite and hydroxyapatite) were investigated for their interaction in cell culture systems in more detail. Qualitative (confocal laser scanning microscopy) and quantitative (flow cytometry) transfection experiments with two cell lines showed the higher transfection efficacy of brushite versus hydroxyapatite. The transfection also revealed a cell type dependency. HEK293 cells were easier to transfect compared to A549 cells. This result was supported by the cytotoxicity results. A549 cells showed a higher degree of tolerance toward the CaP NPs. Further, the impact of the surface modification on the interaction with macrophages and complement as two important components of the innate immune system were considered. The amine surface functionalization had an effect of decreasing the release of proinflammatory cytokines. The complement interaction investigated by a C3a complement activation assay did show no significant differences between CaP NPs without or with amine modification and overall weak interaction. Finally, the degradation of CaP NPs in biological media was studied with respect to the two crystal structures and at acidic and neutral pH. Both amino-modified CaP NPs disintegrate within days at neutral pH, with a notable faster disintegration of brushite NPs at acidic pH. In summary, the fair transfection capability of this amino functionalized CaP NPs together with the excellent biocompatibility, biodegradability, and low immunogenicity make them interesting candidates for further evaluation.

Effects of engineered nanoparticles on the innate immune system

“…The shape of NPs has also been demonstrated to affect interactions with the innate immune system [21,25,36]. Groll et al found that the uptake of nanorods by macrophages was more efficient than the uptake of nanospheres.…”

Bioadhesive Bacterial Microswimmers for Targeted Drug Delivery in the Urinary and Gastrointestinal Tracts

“…However, a preliminary study regarding their effect on the activation of complement system was conducted to have a clearer understanding in this regard. C3a complement activation assay, which was conducted according to a standard protocol mentioned in previous studies, can give some first idea as to what extent the bacteriabots can lead to complement‐activated clearance and trigger immune system. It was already known that the E. coli bacteria can induce the complement system, but the synergic behavior after attaching to microparticles is not known.…”

Nanocaged platforms: modification, drug delivery and nanotoxicity. Opening synthetic cages to release the tiger

“…Immune responses, inflammatory reactions and phagocytosis have been demonstrated by NCs, such as iron oxide NCs 365, 366 . Additionally, cytotoxicity of graphene quantum dots (GQDs) has led to a decrease in expression of the anti-apoptosis protein Bcl-2 and an increase in expression of pro-apoptotic proteins Bax and Bad 367 .…”