Short-term stability of lipid nanoparticles in pre-drawn syringes: PDA Italy Chapter awards the prize for the best thesis

One of the two PDA Italy Chapter Degree Awards was awarded to Giorgia Frigerio. The prize is given to student members of chemistry, pharmacy, pharmaceutical biotechnology and related disciplines for their thesis work in the field of bio/pharmaceutical manufacturing.


PDA Italy Chapter awarded, during the 2023 annual conference in Milan, one of the two PDA Student Awards, for the best master’s degree thesis works, to Giorgia Frigerio.

The scientific work entitled Short-term stability of lipid nanoparticles in pre-drawn syringesa was considered innovative because, at the beginning of the mass vaccination campaign, it supported the hypothesis that vaccine doses can be prepared safely in a dedicated area using aseptic technique and transferred to the hubs without compromising their stability.


As nanosystems market is fast-growing thanks to the undoubted advantages in terms of efficacy and safety, questions are arising about their “real-world” stability. In particular very few data are available on the short-term stability of nanovectors when loaded in disposable syringes.
Pre-drawn syringes are preferred because of the possibility to guarantee appropriate practice standards.
This work provides stability data on nanoparticles in pre-drawn disposable syringes stored at 2–8 °C or 25 °C for at least 5 hours since no data were available in the Summary of Product Characteristics (SPC) at the time of this study. The investigation was carried out using leftover of mRNA loaded lipid nanoparticles (Comirnaty, Pfizer-BioNTech, RNA LNP).
Furthermore, to evidence possible retention of nanosystems onto the syringe barrel, placebo lipid nanovectors (LN) loaded with a fluorescent probe were also prepared and stored in the same experimental conditions. The DLS results evidenced that RNA-LNP as well as fluorescent LN ranged from 80 to 170 nm with a relatively narrow polydispersity index (PDI < 0.2).
These features were maintained after storage at 2-8 °C over at least 5 hours in disposable syringes made of poly(propylene) or poly(carbonate). Only the shaking caused massive aggregation of lipid nanoparticles and mRNA degradation. The adsorption of LN on the barrel surface resulted very low in all cases. As an example, after storage of LN at 25 °C over 1 week, the retained amount was about 3 orders of magnitude lower than the number of particles present in the initial dose. It should also be noted that the use of siliconized barrel partially limited the fraction of LN adsorbed. This preliminary set of data demonstrates the colloidal stability of lipid nanovectors loaded in disposable syringes made of different materials over a period of time of at least 5 hours. This information can be useful in clinical practice when the preparation of the
dose and the administration to patients occurs in different time and setting.