Degradable Cationic Shell Cross-Linked Knedel-like Nanoparticles: Synthesis, Degradation, Nucleic Acid Binding, and in Vitro Evaluation

Abstract

In this work, degradable cationic shell crosslinked knedel-like (deg-cSCK) nanoparticles were developed as an alternative platform to replace similar non-degradable cSCK nanoparticles that have been utilized for nucleic acids delivery. An amphiphilic diblock copolymer poly(acrylamidoethylamine)90-block-poly(DL-lactide)40 (PAEA90-b-PDLLA40) was synthesized, self-assembled in aqueous solution and shell crosslinked using a hydrolyzable crosslinker to afford deg-cSCKs with an average core diameter of 45 ± 7 nm. These nanoparticles were fluorescently labeled for in vitro tracking. The enzymatic- and hydrolytic-degradability, siRNA binding affinity, cell uptake and cytotoxicity of the deg-cSCKs were evaluated. Esterase-catalyzed hydrolysis of the nanoparticles resulted in the degradation of ca. 24% of the PDLLA core into lactic acid within 5 d, as opposed to only ca. 9% degradation from aqueous solutions of the deg-cSCK nanoparticles in the absence of enzyme. Cellular uptake of deg-cSCKs was efficient, while exhibiting low cytotoxicity with LD50 values of ca. 90 μg/mL and 30 μg/mL in RAW 264.7 mouse macrophages and MLE 12 cell lines, respectively, ca. 5–6-fold lower than the cytotoxicity observed for non-degradable cSCK analogs. Additionally, deg-cSCKs were able to complex siRNA at an N/P ratio as low as 2, and were efficiently able to facilitate cellular uptake of the complexed nucleic acids.

Programmed hydrolysis of nanoassemblies by electrostatic interaction-mediated enzymatic-degradation

“…16 The degrees of polymerization and well-defined structures for the polymers were confirmed by a combination of 1 H NMR spectroscopy (Fig. S2, ESI † ) and gel permeation chromatography (GPC) (Fig.…”

Poly(styrene)-b-poly(DL-lactide) copolymer-based nanoparticles for anticancer drug delivery

“…Biocompatibility of PS-PDLLA can be estimated from the biomedical application of each polymer component as reported. 27,31 The result of the cytotoxicity test supports the feasibility of PS-PDLLA NPs as a safe drug delivery vehicle.…”

“…copolymer could be one of the mechanisms of drug release from NPs in biological fluids. 27 It is assumed that the existence of esterases in biological fluids can facilitate disruption of NPs, thereby eliminating the copolymers from the body, and releasing the drug.…”

“…Numerous NPs based on each copolymer component (PS or PDLLA) were fabricated and their characteristics, including toxicity, were investigated. 27,31 It was reported that the cytotoxicity of PS NPs was influenced by the functional group attached on the surface of the NPs, the particle size, and the presence of enzymes or serum. 37 PDLLA has been used as a biocompatible polymer, alone or in a conjugated form, for drug delivery and tissue engineering.…”

Shell-crosslinked knedel-like nanoparticles induce lower immunotoxicity than their non-crosslinked analogs

“…45 nm and 107 nm, respectively. 27 PEGylation and varying degrees of crosslinking did not alter the sizes of cSCKs significantly, and maintained monomodal size distributions and low polydispersity indices (Figure 1). The PEGylation of cSCKs slightly reduced the zeta-potential values, which is usually observed upon decorating the surface of cationic nanoparticles with neutral hydrophilic PEG moieties.…”