Plasma synthesis of Plasma Polymerised Nanoparticles (PPNs): A diagnostics study*

Modern healthcare requires nanocarriers with promising biocompatibility to attach biomolecules for targeted therapeutics and drug delivery. Difficulties associated with currently available nanoparticle systems, such as lipid-based RNA vaccines for SAR-COVID19 include limitations of shelf life, storage temperatures and allergens. A promising alternative focuses on functionalising plasma dust, also known as Plasma Polymerised Nanoparticles (PPNs). PPNs are synthesized from various precursor vapours such as argon, acetylene and nitrogen. The resultant nanoparticles are fully organic, based on combinations of the precursors, contain abundant reactive radicals and high zetapotential to readily attract and covalently attach biomolecules without the need for further reagents. Furthermore, PPNs display high biocompatibility in vivo at extreme concentrations and efficiently attach SiRNA biomolecules on their surfaces. Moreover, nanoparticle sizes can be tuned through modulating the plasma parameters (power and pressure). PPNs are sustainable, requiring only small volumes of the gasses to produce large, readily scalable quantities within short times. Therefore, PPNs make a viable low-cost candidate for biomedical applications such as vaccinations, cancer treatment and diagnostics. However, considering three precursors simultaneously, the plasma dynamics is notoriously complicated as parameters vary, exhibiting complex gas kinetics and chemical reactions. By investigating the plasma conditions through diagnostic techniques, such as Langmuir probe and Optical Emission Spectroscopy (OES), parameters that can control the properties and characteristics of PPNs can be identified. This work explores the electron temperature collected from the OES and locally from the plasma, the electron energy distribution function (EEDF), electron/ion density and time monitoring of evident chemical reactions.