**4. Conclusions**

As demonstrated in this study, silicone nanoparticles (SiNPs) were synthesized from TEOS and PDMS-diol. The existence of PDMS and TEOS in SiNPs was verified through Raman and FTIR spectroscopy. The resultant nanoparticles exhibited a diameter of 330 ± 100 nm and composed of 57% of silicone and 43% of silica. These nanoparticles were further entrapped in hydrogels polymerized from HEMA and NVP. The resultant SiNPs-loaded hydrogel lenses exhibited an unusual correlation between the oxygen permeability (Dk) and the equilibrium water content (EWC): the Dk increased with the content of silicone nanoparticles while the EWC changed insignificantly. Moreover, based on the result of the contact angle and Young's modulus, the loading of SiNPs slightly influenced the wetting surface and mechanical properties. The transparency was reduced to 91% when the content of SiNPs was 1.2 wt%, probably due to the light scattering from the nanoparticles. Further effort to reduce the particle size is underway in our lab. With this work, we demonstrate a novel approach to improve the oxygen permeability without impairing the hydrophilicity of soft contact lenses. These results would be beneficial to the development of soft contact lenses.

**Author Contributions:** N.-P.-D.T. prepared experiments, as well as wrote the original draft. M.-C.Y. supervised the research project and finalized the manuscripts. All authors have read and agreed to the published version of the manuscript.

**Acknowledgments:** This work was supported by the Ministry of Science and Technology, Taiwan through Grant No. MOST 106-2622-E-011-004-CC2.

**Conflicts of Interest:** The authors declare no conflict of interest.
