# The Effect of Human Blood Plasma Conditioning Films on Platelet Tungsten Bag Surface Properties
## 3 Results
### Physicochemistry  
The application of a human plasma CF had a significant effect on the surface physico-chemistry after 1 h or 24 h, with both the Gibbs Free energy (\(\Delta G\)) and the base energy (\(\gamma_{s}\)-) demonstrating significant changes. When a CF was formed on the rough surface, the Gibbs Free energy increased from \(-\)53 mJ/m\({}^{2}\) for the control surface to \(-\)28.5 mJ/m\({}^{2}\) after 1 h and to \(-\)6 mJ/m\({}^{2}\) after 24 h whilst the base energy increased from 7.3 mJ/m\({}^{2}\) for the control surface to 16.8 mJ/m\({}^{2}\) after 1 h and 27.2 mJ/m\({}^{2}\) after 24 h. Similar results were observed when the smooth surface was conditioned, with 1 h CF increasing the Gibbs Free energy to \(-\)7.5 mJ/m\({}^{2}\) and after 24 h it increased to 9.5 mJ/m\({}^{2}\). Further, the acid-base energy increased to 13.9 mJ/m\({}^{2}\) after 1 h and 11.4 mJ/m\({}^{2}\) after 24 h, due to the significant increases in the base energy component which increased from 7.5 mJ/m\({}^{2}\) to 37.9 mJ/m\({}^{2}\) after 1 h and 50 mJ/m\({}^{2}\) after 24 h. A human plasma CF on the flat surface caused an increase in the Gibbs Free energy, with a 1 h incubation increasing it to \(-\)22 mJ/m\({}^{2}\) and a 24 h incubation increasing it to \(-\)5.5 mJ/m\({}^{2}\). Whilst small changes in values were observed, the only other significant change was the increase in base energy from 9.7 mJ/m\({}^{2}\) to 22.7 mJ/m\({}^{2}\) after 1 h and then 29.3 mJ/m\({}^{2}\) after 24 h.  
When a CF was applied on the rough surface (Table 1) combining the bacteria with human plasma, the combination of human plasma with _S. epidermidis_ caused a significant increase in the Gibbs Free energy, from \(-\)53 mJ/m\({}^{2}\) to \(-\)31.3 mJ/m\({}^{2}\) after 24 h, whilst a significant increase in the basic energy was observed after 24 h, from 7.3 mJ/m\({}^{2}\) to 14.9 mJ/m\({}^{2}\). However, when _Ser. marcescens_ and human plasma combined demonstrated a significant increase after 1 h, with the Gibbs Free energy decreased to \(-\)21.5 mJ/m\({}^{2}\) and the basic energy increased to 21.5 mJ/m\({}^{2}\). However, after 24 h no significant changes were apparent. When the smooth surface was conditioned with human plasma and either _S. epidermidis_ or _Ser. marcscens_ both organisms demonstrated a reduction in Gibbs Free energy after 1 h, from \(-50.1\) mJ/m\({}^{2}\) to \(-68.2\) mJ/m\({}^{2}\) for _S. epidermidis_ and \(-57.9\) mJ/m\({}^{2}\) for _Ser. marcscens_ (Table 2). However, after 24 h the Gibbs Free energy values were similar to human plasma alone, with 7.6 mJ/m\({}^{2}\) for human plasma with _S. epidermidis_ and 4.8 mJ/m\({}^{2}\) for human plasma with _Ser. marcscens_. Both organisms demonstrated significantly different values for the other physicochemical properties after 24 h. The combined human plasma plasma and _Ser. marcscens_' CF demonstrated an increase in acid-base energies at 9.2 mJ/m\({}^{2}\) due to the significant increase in base energy (34.7 mJ/m\({}^{2}\)). However, human plasma and _S. epidermidis_ combined 24 h CF demonstrated a significantly reduced the total free energy, Lifschitz van der Waals forces and the base energies (1.2 mJ/m\({}^{2}\), 1.7 mJ/m\({}^{2}\) and 0.9 mJ/m\({}^{2}\) respectively) when compared to the controls (49.6 mJ/m\({}^{2}\), 45.7 mJ/m\({}^{2}\) and 7.5 mJ/m\({}^{2}\)). The conditioning of the flat surface (Table 3) with a combination of human plasma and _S. epidermidis_ caused the Gibbs Free energy to reduce from \(-40.2\) mJ/m\({}^{2}\) to \(-60.5\) mJ/m\({}^{2}\) after 1 h and \(-58.6\) mJ/m\({}^{2}\) after 24 h. A slight reduction in the total free energy was observed after one hour (46.8 mJ/m\({}^{2}\)) but was not significant until 24 h where the total free energy was reduced from 53.3 mJ/m\({}^{2}\) to 38.3 mJ/m\({}^{2}\). However, when a human plasma and _Ser. marcscens_ CF was applied the Gibbs Free energy was initially reduced to \(-63.2\) mJ/m\({}^{2}\) after 1 h but significantly increased to 6.9 mJ/m\({}^{2}\) after 24 h. The total free energy for _Ser.