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蚕丝丝素蛋白膜是一种具有弱碱性和弱酸性的两性荷电膜。因此在丝素膜－水溶液体系中，水溶液ｐＨ值变化会影响丝素膜上溶质的渗透速度和渗透量。丝素膜的等电点ｐＨ≈４．５。丝素膜上药物渗透实验的结果表明：在ｐＨ＝３．０～９．０的范围内，当溶液的ｐＨ＜４．５时，丝素膜带正电，正离子苄三甲氯化铵的渗透系数下降；当溶液的ｐＨ＞４．５时，丝素膜带负电，负离子酚磺酸钠的渗透系数明显下降。中性分子间苯二酚在丝素膜上的透过不受外部溶液ｐＨ值变化的影响。当溶液的ｐＨ＞８或ｐＨ＞４．５时，离子化的药物５－氟尿嘧啶或维生素Ｃ的渗透系数明显变小，这是因为两者分别在ｐＨ＝８（ｐＫａ＝８．０）和ｐＨ＝４．５（ｐＫａ＝４．２５）以上变成带电离子。这表明离子化药物在蚕丝丝素膜上的渗透速度和渗透量对溶液ｐＨ值变化有较好的响应特性。
Silk fibroin protein film is a kind of weakly alkaline and weak acid gender charge film. Therefore, in the silk fibroin-water system, the pH value of the aqueous solution will affect the penetration rate and amount of solute on the silk fibroin membrane. The isoelectric point of fibroin membrane pH≈4.5. The results of drug permeation experiments on silk fibroin films showed that the silk fibroin films were positively charged when the pH of the solution was less than 4.5 in the range of pH = 3.0-9.0. When the solution pH was> 4.5, the membrane was negatively charged, and the osmotic coefficient of sodium phenolsulfonate decreased significantly. The permeation of the neutral molecular resorcinol in the silk fibroin membrane is not affected by the pH change of the external solution. The osmotic coefficient of the ionized drug 5-Fluorouracil or Vitamin C is significantly lower when the pH of the solution is> 8 or pH> 4.5 because both are stable at pH = 8 (pKa = 8.0) and pH = 4.5 (pKa = 4.25) The above becomes charged ions. This shows that the ionized drug penetration rate in the silk fibroin membrane and the amount of penetration on the pH value of the solution has better response characteristics.