Covalent and Noncovalent Conjugation of Degradable Polymer Nanoparticles to T Lymphocytes

Abstract

Cells are attractive as carriers that can help to enhance control over the biodistribution of polymer nanomedicines. One strategy to use cells as carriers is based on the cell surface immobilization of the nanoparticle cargo. While a range of strategies can be used to immobilize nanoparticles on cell surfaces, only limited effort has been made to investigate the effect of these surface modification chemistries on cell viability and functional properties. This study has explored seven different approaches for the immobilization of poly(lactic acid) (PLA) nanoparticles on the surface of two different T lymphocyte cell lines. The cell lines used were human Jurkat T cells and CD4 + T EM cells. The latter cells possess blood−brain barrier (BBB) migratory properties and are attractive for the development of cell-based delivery systems to the central nervous system (CNS). PLA nanoparticles were immobilized either via covalent active ester−amine, azide−alkyne cycloaddition, and thiol−maleimide coupling, or via noncovalent approaches that use lectin−carbohydrate, electrostatic, or biotin−NeutrAvidin interactions. The cell surface immobilization of the nanoparticles was monitored with flow cytometry and confocal microscopy. By tuning the initial nanoparticle/cell ratio, T cells can be decorated with up to ∼185 nanoparticles/cell as determined by confocal microscopy. The functional properties of the nanoparticle-decorated cells were assessed by evaluating their binding to ICAM-1, a key protein involved in the adhesion of CD4 + T EM cells to the BBB endothelium, as well as in a two-chamber model in vitro BBB migration assay. It was found that the migratory behavior of CD4 + T EM cells carrying carboxylic acid-, biotin-, or Wheat germ agglutinin (WGA)-functionalized nanoparticles was not affected by the presence of the nanoparticle payload. In contrast, however, for cells decorated with maleimide-functionalized nanoparticles, a reduction in the number of migratory cells compared to the nonmodified control cells was observed. Investigating and understanding the impact of nanoparticle−cell surface conjugation chemistries on the viability and properties of cells is important to further improve the design of cell-based nanoparticle delivery systems. The results of this study present a first step in this direction and provide first guidelines for the surface modification of T cells, in particular in view of their possible use for drug delivery to the CNS.

Protected amine-functional initiators for the synthesis of α-amine homo- and heterotelechelic poly(2-ethyl-2-oxazoline)s

“…After collecting the product fractions, the solvent was removed under reduced pressure, which yielded tert-butyl (3-hydroxypropyl) carbamate as a colourless liquid (yield: 1.12 g, 56%). 1 H NMR (400 MHz, CDCl 3 ): δ = 3.65 (t, J = 5.7 Hz, 2H, HO-…”

“…However, the values observed for the CROP using phthalimide-NH 2 -C3-Tos were higher at any given conversion despite the same targeted [M]/[I] ratio. Further evaluation of the initiator consumption of phthalimide-NH 2 -C3-Tos by 1 H NMR measurements (Fig. S23 †) revealed a slow but significantly higher initiator conversion (70.5%) compared to the 80 °C oil bath polymerization (58%).…”

“…To determine the percentage of functionality of each terminus, all polymers were analyzed by 1 H NMR spectroscopy. To this end, the actual monomer-toinitiator feed ratio was determined by 1 H NMR spectroscopy at time point t = 0. The integrals of the phthalimide peaks were set to 4H and subsequently the integral value corresponding to the methyl group of the EtOx monomer (3H, 1.05 ppm) was determined (Fig.…”

“…In polymeric nanomedicine research, polymers bearing functional moieties are essential. Functionalities allow conjugation or complexation of cargo such as proteins, 1–3 drugs, 4,5 and genes, 6,7 and targeting and imaging agents. 8,9 They also offer the potential to form complex architectures such as hydrogels, 10 combs, 11 brushes, 12 stars 13,14 and core cross linked micelles.…”

“…1 H NMR (400 MHz, CDCl 3 ): δ = 3.44 (t, J = 6.5 Hz, 2H, Br-CH 2 -CH 2 ), 3.27 (d, J = 5.7 Hz, 2H, CH 2 -CH 2 -NH), 2.13-1.99 (m, 2H, -CH 2 -CH 2 -CH 2 -), 1.44 (s, J = 32.5 Hz, 9H, -C-CH 3 )…”