化粧品含奈米級二氧化鈦之防曬係數研究   全文下載

Sun Protection Factor Analysis of Sunscreens Containing Titanium Dioxide Nanoparticles

二氧化鈦（TiO2）具寬廣之吸收波長範圍，可有效防禦紫外線傷害，為市售防曬產品中常用之物理性防曬劑。為瞭解微細化型態之二氧化鈦對紫外線UVB之防護力，本研究探討兩種不同顆粒大小之二氧化鈦（奈米級20 nm及次微米級170 nm）對防曬係數之影響，進行體外試驗與人體防曬試驗之測試。體外試驗顯示奈米二氧化鈦乳霜之防曬係數值高於次微米二氧化鈦乳霜，人體防曬試驗結果驗證此結果，並且呈現良好in vivo – in vitro之關係性。奈米二氧化鈦乳霜之防曬係數值隨著所含二氧化鈦濃度之增加而增加，成正比關係。從掃描式電子顯微鏡結果推論，含奈米二氧化鈦乳霜由於微細化粒子凝結而形成多層面的聚集，顆粒與顆粒間聚集空隙變小，對紫外光之遮避性較大，而得到較高之防曬係數值，因此提高對皮膚之防曬效率。

The effect of micronization on sun protection factor (SPF) were tested on two types of titanium dioxide (TiO2) with primary particle sizes of 20 nm and 170 nm. Oil/water creams with 5%, 10%, and 20% concentrations of each type of TiO2 were prepared, and SPF was measured using both in vitro and in vivo methods. In vitro analysis demonstrated that submicron-sized TiO2 cream had a lower SPF value than nanosized TiO2 formulations of the same concentration. In vivo experiments confirmed this result, and a strong correlation between in vitro and in vivo measurements was observed. Furthermore, the SPF values of nanosized TiO2 sunscreen were concentration-dependent in the range of 5% to 20%. Scanning electron microscopy results indicate that the higher SPF of nanosized TiO2 formulations may be due to the formation of multilayer agglomerates by small particles at nano-scales, leading to a reduced void space between particles and a more efficient barrier to protect skin from sunlight.