## 3 Inventory Data  
### Inventory Data for the Synthesis, Purification and Drying of Gold Nanoparticles  
The synthesis, purification and drying of AuNPs required a detailed review of the input data, which the company provided. Further, it was supplemented with datasets from the Ecoinvent 3.8 database [15]. The process involves synthesizing gold (III) chloride trihydrate (HauCl4 \(\times\) 3H2O), purification and drying. The input materials, energy consumption, and emissions associated with these stages were evaluated, to form a comprehensive Life Cycle Inventory (LCI) (Table 2). \begin{table}
\begin{tabular}{c c c} \hline
**Input Category** & **Normalization Factors** & **Weighting Factor** \\ \hline Acidification & 55.57 & 0.0620 \\ Climate change & 7553.08 & 0.2106 \\ Ecotoxicity, freshwater & 56,716.59 & 0.0192 \\ Particulate Matter & \(5.95\times 10^{-4}\) & 0.0896 \\ Eutrophication marine & 19.55 & 0.0296 \\ Eutrophication, freshwater & 1.61 & 0.0280 \\ Eutrophication, terrestrial & 176.75 & 0.0371 \\ Human toxicity, cancer & \(1.73\times 10^{-5}\) & 0.0213 \\ Human toxicity, non-cancer & \(1.29\times 10^{-4}\) & 0.0184 \\ Ionizing radiation, human health & 4220.16 & 0.0501 \\ Land use & 819,498.18 & 0.0794 \\ Ozone depletion & \(5.23\times 10^{-2}\) & 0.0631 \\ Photochemical ozone formation—human health & 40.86 & 0.0478 \\ Resource use, fossils & 65,004.26 & 0.0832 \\ Resource use, minerals and metals & \(6.36\times 10^{-2}\) & 0.0755 \\ Water use & 11,468.71 & 0.0851 \\ \hline \end{tabular}
\end{table} 
Table 1: Normalization factors [13] and weighting factors [14] applied in the study. \begin{table}
\begin{tabular}{c c c c} \hline
**Data** & **Quantity** & **Unit** & **Dataset** \\ \hline HAuCl4 \(\times\) 3H2O & & & \\ \hline Gold (Au) & 2.50 & g & \(\Rightarrow\)Market for gold \(\mid\)gold \(\mid\)Cutoff, U\(\approx\) 1 \\ \hline Hydrogen chloride (HCI) & 1.85 & g & \(\Rightarrow\)Market for hydrochloric acid, without water, in 30\% solution state \(\mid\)Hydrochloric acid, without water, in 30\% solution state \(\mid\)Cutoff, U\(\approx\) \\ \hline Nitric acid (HNO3) & 0.80 & g & \(\Rightarrow\)Market for nitric acid, without water, in 50\% solution state \(\mid\) nitric acid, without water, in 50\% solution state \(\mid\)Cutoff, U\(\approx\) \\ \hline Nitrogen & 423.45 & kg & \(\Rightarrow\)Market for nitrogen, liquid \(\mid\) nitrogen, liquid \(\mid\)Cutoff, U\(\approx\) \\ \hline Hydrogen & 25.18 & kg & \(\Rightarrow\)Market for hydrogen, gaseous \(\mid\)hydrogen, gaseous \(\mid\)Cutoff, U\(\approx\) \\ \hline Polyvinylpyrrolidone (PVP) & 453.60 & g & \(\Rightarrow\)Market for \\  & & & N-methyl-2-pyrrolidone \(\mid\)N-methyl-2-pyrrolidone \(\mid\)Cutoff, U\(\approx\) \\ \hline Water (0.1 \(\upmu\)S/m) & 212.80 & L & \(\Rightarrow\)Market for water, ultrapure \(\mid\)Water, ultrapure \(\mid\)Cutoff, U\(\approx\) \\ \hline \end{tabular}
\end{table} 
Table 2: Inventory for synthesizing, purifying, and drying gold nanoparticles (AuNPs). For an inventory of the data for electricity for the synthesis, purification and drying of AuNPs, we used the >>market group for electricity, medium voltage! electricity, medium voltage! Cutoff, U<< from the Ecoinvent database (Couf, 2018). This dataset does not include losses and relevant exchanges (transport, transport infrastructure, etc.). They are present in the contained markets. This is the market group for >>electricity, medium voltage, in Europe without Switzerland<<. The inventory of electricity used for synthesizing, purifying and drying AuNPs is presented in Table 3.  
The inventory data for the transport of substances for the synthesis, purification and drying of AuNPs include transport freight and container shipping. Transport freight was modelled as transporting 1 metric ton of goods over 1 km within Europe using a 16-32 metric ton diesel-powered lorry meeting EURO5 (Euro, 2018) emission standards. The average load factor is 5.79 tons, with a gross vehicle weight of 15.79 tons and a lifetime capacity of 540,000 km.