Substrate geometry modulates self-assembly and collection of plasma polymerized nanoparticles

Abstract

Plasma polymerized nanoparticles (PPN) formed in plasma reactors have been considered undesirable in technological applications. More recently however, PPN were proposed as a new class of multifunctional nanocarriers for drug delivery. Therefore, synthesis of PPN requires cost-effective collection strategies that maximize yield and improve reproducibility. This work shows that the collection of PPN in dusty plasmas is modulated by modifying the geometry of substrates from planar to well-shaped collectors. The electric field profile around the wells acts as an electrostatic lens, concentrating nanoparticles and significantly bolstering process yield. The aggregation of PPN is governed by a balance between plasma expansion throughout the wells, inter-particle repulsion, particle size and density. PPN are readily dispersed in aqueous solution yielding monodisperse populations. The use of a disposable wellshape collector provides a cost-effective nanoparticle collection approach that can be adopted in a wide range of plasma polymerization configurations without the need for reactor redesign .

Plasma polymerized nanoparticles effectively deliver dual siRNA and drug therapy in vivo

“…To produce PPNs, a radiofrequency discharge is sustained in a vacuum chamber at a constant power and working pressure (100 W and 150 mTorr respectively) using a reactive mixture of acetylene (C 2 H 2 ), nitrogen (N 2 ) and argon (Ar). This process produces a uniform distribution of PPNs which can be collected and concentrated directly from the plasma bulk into well-shaped collectors 33 , such as tissue culture well plates (Fig. 2 a).…”

“…The reactive surface of PPNs eliminates the need for linker-chemistry and the functionalization process can be easily adopted in any laboratory setting. The efficient synthesis process uniformly yields nanoparticles at a mass rate of 85 mg/h 33 . PPNs have a long shelf-life and can be stored at room temperature up to at least 16 months after plasma synthesis for subsequent functionalization with molecular cargo 27 .…”

“…The carbonaceous nanoclusters assemble into spherical-like nanoparticles (Fig. 2 b–d) which are dragged outside the plasma by ion drag and thermophoretic forces 27 , 33 . Chemical characterization of PPNs was consistent with our previous reports on PP-derived materials 33 , 34 , confirming incorporation of elemental carbon and nitrogen into the nanoclusters followed by surface restructuring due to oxidation (Figure S1 a) and the presence of amine and carboxyl functional moieties (Figure S1 b).…”

“…These plasmas are often characterised by the formation of particulates in the chamber which compromise process efficiency. While long considered a by-product in plasma-based thin film coating, etching and energy applications 31 , 32 , we recently demonstrated that plasma conditions can be optimized to produce high yields of stable PPNs 33 with well-defined surface properties, favourable for biological applications 27 . Nanoparticle synthesis using this approach is a bottom-up dry process, readily scalable and cost-effective (Fig.…”

“…Nanoparticle synthesis using this approach is a bottom-up dry process, readily scalable and cost-effective (Fig. 1 a), making it compatible with commercial production 33 . Multi-functionalization of PPNs is achieved in a one-step process by simply mixing the nanoparticles with the molecular payload in aqueous solution, eliminating the need for linker intermediates (Fig.…”